Lithium-ion rechargeable battery

Abstract

To provide a secondary battery with high capacity and less deterioration, or a novel power storage device.SOLUTION: A secondary battery includes a positive electrode and a negative electrode. The negative electrode includes a first active material, a second active material, and a graphene compound. At least a part of a surface of the first active material includes a region that is covered with a second active material. At least a part of a surface of the second active material and a surface of the first active material includes a region that is covered with the graphene compound. The first active material contains graphite. The second active material contains silicon. The capacity of the positive electrode is 50% or more and less than 100% of the capacity of the negative electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to electrodes and methods for manufacturing them, or to active materials contained in electrodes and methods for manufacturing them. Or, it relates to secondary batteries and methods for manufacturing them, or it includes vehicles, etc., that have secondary batteries. This relates to mobile devices, as well as portable information terminals, electronic devices, etc.

[0002] One aspect of the present invention relates to a product, a method, or a method of manufacture; or, the present invention relates to a process , relating to machines, manufacturers, or compositions of matter One aspect of the present invention relates to semiconductor devices, display devices, light-emitting devices, energy storage devices, lighting devices, and electronic devices. , or relating to methods for manufacturing them.

[0003] In this specification, "electronic equipment" refers to all devices that have an energy storage device. Electro-optical devices and information terminal devices with energy storage devices are all electronic devices.

[0004] In this specification, "energy storage device" refers to all elements and devices that have an energy storage function. For example, energy storage devices such as lithium-ion secondary batteries (also called secondary batteries), This includes lithium-ion capacitors and electric double-layer capacitors. [Background technology]

[0005] In recent years, various energy storage technologies have emerged, such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries. The development of such devices is thriving, particularly lithium-ion batteries, which offer high power output and high energy density. Rechargeable batteries are used in mobile devices such as mobile phones, smartphones, and laptop computers. In addition, portable music players, digital cameras, medical equipment, or hybrid vehicles (HV), electric Next-generation clean energy vehicles such as electric vehicles (EVs) or plug-in hybrid vehicles (PHVs) With the development of the semiconductor industry, including energy-powered vehicles, demand for rechargeable batteries has expanded rapidly. As a potential source of energy, it has become indispensable in today's information society. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-216751 [Patent Document 2] Special Publication No. 2019-522886 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Secondary batteries used in mobile vehicles such as electric vehicles and hybrid vehicles extend the driving range. Therefore, the capacity needs to be increased.

[0008] Furthermore, with the increasing functionality of mobile devices, power consumption is also increasing. The secondary batteries used are required to be smaller and lighter. Therefore, they are used in mobile devices. There is also a demand for higher capacity in secondary batteries.

[0009] In addition to their stability, high capacity is also important for rechargeable batteries. Silicon Alloy materials such as ionized materials have high capacity and are promising as active materials for secondary batteries. However, Furthermore, alloy materials with high charge / discharge capacity undergo pulverization of the active material due to volume changes associated with charging and discharging. Problems such as delamination occur, and sufficient cycle characteristics are not obtained.

[0010] To improve the problems of alloy materials as described above, alloy materials and graphite or carbonaceous materials Compounding with other materials is being considered. Patent Document 1 describes the bonding of silicon-containing particles and carbon-containing particles. A composite material is described in which a coating layer made of carbon is formed on the surface of a porous particle nucleus composed of a combination of particles. Patent Document 2 describes a composite material containing silicon (Si), lithium fluoride (LiF), and carbon material. Particles are described. However, in all of the above literature, the combined charge and discharge To adequately resolve the problems of pulverization and detachment of active material due to the expansion of gold-based materials It's not there yet.

[0011] The electrodes of a secondary battery are composed of materials such as active material, conductive material, and binder. The higher the proportion of materials that contribute to capacity, such as the active material, the greater the capacity of the secondary battery. This is possible. By having a conductive material in the electrode, the conductivity of the electrode is enhanced, resulting in excellent output characteristics. This can be obtained. Also, in the charging and discharging of secondary batteries, the active material repeatedly expands and contracts. As a result, the active material may collapse, the conductive path may be interrupted, etc., at the electrode. In such cases, the electrode having a conductive material and a binder can cause the active material to disintegrate and conduct The interruption of the electric path can be suppressed. On the other hand, by using a conductive material and a binder, As a result, the proportion of active material decreases, which may reduce the capacity of the secondary battery.

[0012] One aspect of the present invention aims to provide an electrode having excellent properties. One aspect of the invention aims to provide an active material having excellent properties. One aspect of the invention aims to provide a novel electrode.

[0013] Alternatively, one aspect of the present invention aims to provide a mechanically robust negative electrode. One aspect of the present invention aims to provide a mechanically robust positive electrode. Alternatively, the present invention One aspect of the present invention aims to provide a high-capacity negative electrode. Alternatively, one aspect of the present invention is The objective is to provide a positive electrode with high capacity. Alternatively, one aspect of the present invention provides a positive electrode with less degradation. The objective is to provide a negative electrode. Alternatively, one aspect of the present invention provides a positive electrode that exhibits less degradation. The task is to accomplish this.

[0014] Alternatively, one aspect of the present invention aims to provide a secondary battery that undergoes less degradation. One aspect of the present invention aims to provide a highly safe secondary battery. One aspect of the invention aims to provide a secondary battery with high energy density. Alternatively, One aspect of the present invention aims to provide a novel secondary battery.

[0015] Furthermore, the description of these problems does not preclude the existence of other problems. One embodiment does not need to solve all of these problems. It is possible to extract other problems from the description of the claims. [Means for solving the problem]

[0016] One aspect of the present invention comprises a positive electrode and a negative electrode, wherein the negative electrode comprises a first active material and a second active material. The material comprises a graphene compound, and at least a portion of the surface of the first active material is a second active material Having a region covered with a substance, at least one of the surfaces of the second active material and the first active material The part has a region covered with a graphene compound, the first active material has graphite, and the second active The material contains silicon, and the capacity of the positive electrode is 50% or more but less than 100% of the capacity of the negative electrode. It is a rechargeable battery.

[0017] Furthermore, one aspect of the present invention has a positive electrode and a negative electrode, the negative electrode comprising a first active material and a second The device comprises an active material and a graphene compound, wherein at least a portion of the surface of the first active material is a second It has a region covered with the active material, and less than the surface of the second active material and the surface of the first active material Both have a region covered with a graphene compound, and the first active material has graphite, and The second active material has silicon, and in a fully charged state, the second active material has Si-Si bonds. It is a rechargeable battery.

[0018] Furthermore, one aspect of the present invention comprises a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is a first active material The first active material comprises a second active material and a graphene compound, and at least one of the surfaces of the first active material The part has a region covered with a second active material, the surface of the second active material and the surface of the first active material At least a portion of the surface has a region covered with a graphene compound, and the first active material is graphite The second active material has silicon, and the capacity of the positive electrode is 50% or more of the capacity of the negative electrode. It is a secondary battery with a capacitance of less than 100% and an ionic liquid electrolyte.

[0019] Furthermore, one aspect of the present invention comprises a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is a first active material The first active material comprises a second active material and a graphene compound, and at least one of the surfaces of the first active material The part has a region covered with a second active material, the surface of the second active material and the surface of the first active material At least a portion of the surface has a region covered with a graphene compound, and the first active material is graphite The second active material has silicon, and in a fully charged state, the second active material is Si- This is a secondary battery that has Si bonds and an ionic liquid electrolyte.

[0020] In the secondary battery described in any one of the above, the ionic liquid is Li, which is 2 mol / L or more. It is desirable to have both FSI and EMI-FSI.

[0021] In the secondary battery described in any one of the above, the positive electrode is made of magnesium, fluorine, or aluminum. It has lithium cobaltate containing nium and nickel, and lithium cobaltate is magnesium The optimal concentration is one or more of the following selected elements: nesium, fluorine, and aluminum. It is desirable to have a large area in the surface layer.

[0022] In the secondary battery described in any one of the above, the first active material has a particle size of 5 μm or larger. The first active material contains graphite, and the second active material preferably has silicon with a particle size of 250 nm or less. stomach.

[0023] One aspect of the present invention is a vehicle having a secondary battery as described in any one of the above.

[0024] One aspect of the present invention is an energy storage system having a secondary battery as described in any one of the above.

[0025] One aspect of the present invention is an electronic device having a secondary battery as described in any one of the above. [Effects of the Invention]

[0026] According to one aspect of the present invention, an active material having excellent properties can be provided. It is possible to provide electrodes having specific characteristics. Furthermore, according to one aspect of the present invention, a novel electrode We can provide the ultimate.

[0027] Furthermore, according to one aspect of the present invention, a mechanically robust negative electrode can be provided. According to one aspect of the invention, a mechanically robust positive electrode can be provided. Depending on the method, a negative electrode with high capacity can be provided. Furthermore, according to one aspect of the present invention, capacity A positive electrode with high performance can be provided. Furthermore, according to one aspect of the present invention, a negative electrode with less degradation can be provided. It can be provided. Furthermore, according to one aspect of the present invention, a positive electrode with less degradation can be provided. Cut.

[0028] Furthermore, according to one aspect of the present invention, a secondary battery with less degradation can be provided. According to one aspect of the present invention, a highly safe secondary battery can be provided. In one embodiment, a secondary battery with high energy density can be provided. In one embodiment, a novel secondary battery can be provided.

[0029] Furthermore, the description of these effects does not preclude the existence of other effects. One embodiment does not necessarily have to possess all of these effects. Furthermore, other effects may be considered. This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings It is possible to extract effects other than those mentioned above from the descriptions in the surfaces, claims, etc. [Brief explanation of the drawing]

[0030] [Figure 1] Figures 1A and 1B show examples of cross-sections of electrodes. Figure 1C illustrates the capacitance ratio between the positive and negative electrodes. [Figure 2] Figures 2A to 2C illustrate the capacity ratio between the positive and negative electrodes, and the voltage of the secondary battery. [Figure 3] Figure 3A shows an example of particles present in the negative electrode. Figures 3B and 3C show the change in particle shape during charging and discharging. [Figure 4]Figures 4A and 4B are diagrams relating to the calculation of the negative electrode according to one embodiment of the present invention. [Figure 5] Figure 5 is a diagram relating to the calculation of the negative electrode according to one embodiment of the present invention. [Figure 6] Figures 6A to 6C are diagrams relating to the calculation of the negative electrode in one embodiment of the present invention. [Figure 7] Figure 7 shows an example of a method for fabricating electrodes. [Figure 8] Figures 8A and 8B show examples of graphene compound models. [Figure 9] Figure 9 shows a cross-sectional structure of a positive electrode according to one embodiment of the present invention. [Figure 10] Figures 10A1 to 10C2 show the cross-sectional structure of a positive electrode active material composite according to one embodiment of the present invention. [Figure 11] Figure 11A is a top view of a positive electrode active material according to one embodiment of the present invention, and Figures 11B and 11C are cross-sectional views of a positive electrode active material according to one embodiment of the present invention. [Figure 12] Figure 12 illustrates the crystal structure of a positive electrode active material according to one embodiment of the present invention. [Figure 13] Figure 13 shows the XRD pattern calculated from the crystal structure. [Figure 14] Figure 14 illustrates the crystal structure of the positive electrode active material in the comparative example. [Figure 15] Figure 15 shows the XRD pattern calculated from the crystal structure. [Figure 16] Figure 16 shows an example of a TEM image where the crystal orientation is roughly consistent. [Figure 17] Figure 17A is an example of a STEM image where the crystal orientation is roughly consistent. Figure 17B is the FFT of the region of the rock salt crystal RS, and Figure 17C is the FFT of the region of the layered rock salt crystal LRS. [Figure 18] Figure 18A is an exploded perspective view of a coin-type rechargeable battery, Figure 18B is a perspective view of a coin-type rechargeable battery, and Figure 18C is a cross-sectional perspective view thereof. [Figure 19]Figure 19A shows an example of a cylindrical secondary battery. Figure 19B shows an example of a cylindrical secondary battery. Figure 19C shows an example of multiple cylindrical secondary batteries. Figure 19D shows an example of an energy storage system with multiple cylindrical secondary batteries. [Figure 20] Figures 20A and 20B illustrate examples of secondary batteries, while Figure 20C shows the inside of a secondary battery. [Figure 21] Figures 21A to 21C illustrate an example of a secondary battery. [Figure 22] Figures 22A and 22B show the external appearance of a secondary battery. [Figure 23] Figures 23A to 23C illustrate the method for manufacturing a secondary battery. [Figure 24] Figures 24A to 24C show examples of battery pack configurations. [Figure 25] Figures 25A and 25B illustrate examples of secondary batteries. [Figure 26] Figures 26A to 26C illustrate an example of a secondary battery. [Figure 27] Figures 27A and 27B illustrate an example of a secondary battery. [Figure 28] Figure 28A is a perspective view of a battery pack showing one embodiment of the present invention, Figure 28B is a block diagram of the battery pack, and Figure 28C is a block diagram of a vehicle having a motor. [Figure 29] Figures 29A to 29D illustrate an example of a transport vehicle. [Figure 30] Figures 30A and 30B illustrate an energy storage device according to one embodiment of the present invention. [Figure 31] Figure 31A shows an electric bicycle, Figure 31B shows the secondary battery of an electric bicycle, and Figure 31C illustrates an electric motorcycle. [Figure 32] Figures 32A to 32D illustrate an example of an electronic device. [Figure 33]Figure 33A shows an example of a wearable device, Figure 33B shows a perspective view of a wristwatch-type device, and Figure 33C is a diagram illustrating the side view of a wristwatch-type device. Figure 33D is a diagram illustrating an example of wireless earphones. [Figure 34] Figures 34A and 34B are SEM images of the electrodes. [Figure 35] Figures 35A and 35B are graphs showing the cycle characteristics. [Figure 36] Figures 36A and 36B are graphs showing the cycle characteristics. [Figure 37] Figures 37A and 37B are graphs showing the discharge characteristics. [Modes for carrying out the invention]

[0031] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention This is not limited to the description below, and its form and details can be changed in various ways, as is the case for those skilled in the art. This will be easily understood. Furthermore, the present invention shall be interpreted as being limited to the contents of the embodiments described below. It is not something that should be done.

[0032] Furthermore, in the drawings, the size, layer thickness, or area may be exaggerated for clarity. This may be the case. Therefore, it is not necessarily limited to that scale.

[0033] Furthermore, the ordinal numbers used in this specification, etc., as "1st," "2nd," etc., are used for convenience only. It does not indicate the order of processes or stacking order. Therefore, for example, "the first" should be written as "the second". This can be explained by appropriately replacing it with "of" or "the third of," etc. The ordinal numbers described herein do not correspond to the ordinal numbers used to specify one aspect of the present invention. There are cases where this is the case.

[0034] Furthermore, in this specification, the term "particle" is not limited to spherical shapes (circular cross-sections), The cross-sectional shape of individual particles can be elliptical, rectangular, trapezoidal, triangular, square with rounded corners, or asymmetrical. Shape is also important, and individual particles may even be amorphous.

[0035] (Embodiment 1) This embodiment describes an example of a secondary battery according to one aspect of the present invention.

[0036] [Example of a secondary battery configuration] The following describes a secondary battery having a positive electrode, a negative electrode, and an electrolyte.

[0037] Figure 1A is a schematic cross-sectional view showing the inside of a secondary battery according to one embodiment of the present invention. The negative shown in Figure 1A Electrode 570a, positive electrode 570b, and electrolyte 576 are coin-type secondary electrodes as shown in the embodiments described later. It can be applied to batteries, cylindrical rechargeable batteries, and laminated rechargeable batteries, etc. Negative electrode 57 0a is the negative electrode current collector 571a and the negative electrode active material layer 5 formed in contact with the negative electrode current collector 571a. It includes at least 72a. The positive electrode 570b is the positive electrode current collector 571b and the positive electrode current collector 571b It includes at least a positive electrode active material layer 572b formed in contact with the surface. Figure 1B shows the same as in Figure 1A. Figure 1C is an enlarged view of the area enclosed by dashed line C in Figure 1A. This diagram illustrates the capacity ratio of the negative electrode 570a and the positive electrode 570b in the region. (Secondary battery) The negative electrode 570a and the positive electrode 570b may have a separator between them.

[0038] [Capacitance ratio of negative electrode to positive electrode] The negative electrode characteristic curve 560a and positive electrode characteristic curve shown in Figures 1C, 2A, 2B, and 2C. B560b is a pair of opposing pairs of pairs in the region enclosed by dashed lines A and B in Figure 1A. The negative electrode 570a and positive electrode 570b have the same area, negative electrode active material layer 572a and positive electrode active material This is a characteristic curve showing the relationship between capacitance and potential in layer 572b.

[0039] In the negative electrode characteristic curve 560a in Figure 1C, the capacity C1 is such that the negative electrode 570a can be charged and discharged. This is the total capacity. The total capacity that the negative electrode 570a can charge and discharge is, for example, the negative electrode 570a and lithium A half-cell containing a um metal was fabricated and a constant current discharge (0.2C, lower limit voltage 0.01V) was performed. ) followed by constant voltage discharge (lower limit current density 0.02C), then constant current charging (0.2C, upper limit voltage) This refers to the charging capacity when 1V is applied. Also, the positive electrode characteristic curve 560 in Figure 1C. In b, capacity C2 is the capacity of the positive electrode when the secondary battery is fully charged. The fully charged state of a secondary battery is, for example, the rated capacity as defined in JIS C8711 (2013). This refers to the state of charge that allows for a certain quantity to be obtained.

[0040] The capacity ratio of the negative electrode 570a and the positive electrode 570b in a secondary battery is given by the negative electrode 570a having the same area as the positive electrode 570b. In 0a and positive electrode 570b, when the capacity of negative electrode 570a is set to 100%, the positive electrode 570 This shows the capacity of b as a percentage. For example, as shown in Figure 2A, the capacity of the negative electrode 570a is If the capacitance of the positive electrode 570b is equal to that of the negative electrode 570a, then the capacitance ratio of the negative electrode 570a to the positive electrode 570b is 100%. That is the case.

[0041] Next, consider the case where the capacitance ratio of the negative electrode 570a to the positive electrode 570b is lower than 100%, as shown in Figure 1. Let's explain using C. When the capacity ratio is lower than 100%, it means that the negative electrode 570a is capable of charging and discharging. This indicates that the total capacity is greater than the charge / discharge capacity of the positive electrode 570b. As shown in Figure 1C, the capacitance C1 of the negative electrode 570a is greater than the capacitance C2 of the positive electrode 570b. Yes.

[0042] Thus, if the capacity ratio is lower than 100%, the excess capacity C1 of the negative electrode 570a is Although some amount is generated, it is easier to suppress unintended lithium ion deposition at the negative electrode 570a. This has the advantage. Furthermore, in a secondary battery having a negative electrode 570a according to one aspect of the present invention, as will be described later... Preferably, the capacity is 50% or more but less than 100%, more preferably 70% or more but less than 90%. In this case, a secondary battery with high charge / discharge capacity and good charge / discharge cycle characteristics can be obtained. be.

[0043] Next, let's explain the voltage of a secondary battery. The voltage of a secondary battery is the difference between the positive electrode potential and the negative electrode potential. This can be considered as follows: For example, in the case where the capacitance ratio of the negative electrode 570a and the positive electrode 570b is 100% The voltage of the combined secondary battery is shown as ΔVa in Figure 2A. Also, the capacity ratio is lower than 100%. The case is shown as ΔVb in Figure 2B. As shown in Figure 2B, the case where the capacity ratio is lower than 100% In addition, the negative electrode 570a will be used in a region with a high operating potential range, therefore the voltage of the secondary battery It will decrease.

[0044] Next, in Figure 2C, when the capacitance ratio of the negative electrode 570a to the positive electrode 570b is lower than 100% Here, we will show an example where the secondary battery voltage does not decrease. Here, ΔVa and Δ shown in Figure 2C This indicates that Vc and have the same voltage value. Figure 2B shows the usable potential range of the positive electrode 570b. The range is the same as the usable potential range of the positive electrode 570b in Figure 2A, and in this case the secondary battery As mentioned above, the pressure ΔVb is smaller than ΔVa. Here, as shown in Figure 2C, the positive electrode 5 When extending the usable potential range of 70b to higher potentials, the secondary battery voltage ΔVc is similar to ΔVa. The value will be high.

[0045] As shown in Figure 2C, when the capacitance ratio of the negative electrode 570a to the positive electrode 570b is lower than 100% Even in this case, it is possible to obtain a secondary battery in which the voltage does not drop. In this case, the positive electrode 57 Since 0b will be exposed to a relatively high potential, the positive electrode 570b will be subjected to high-potential charging and discharging. High resistance is required. The positive electrode active material 100 shown in one aspect of the present invention is in a high-potential charged state Because it can adopt a stable crystal structure, it is suitable as the active material for the positive electrode 570b. Details of the positive electrode active material 100 will be described later.

[0046] [Negative electrode] Figure 1B is an enlarged view of the area enclosed by the dashed line C in Figure 1A. As shown in Figure 1B, The highly active material layer 572a consists of a first active material 581, a second active material 582, and a sheet-like shape. The material comprises graphene compound 583 and electrolyte 576. Figure 3A shows the graphene compound 583. The rafen compound 583 affects the second active material 582 located on the surface of the first active material 581. The way in which the first active material 581 comes into contact with the other material, such as covering, enveloping, or clinging to it. This is a schematic diagram illustrating the following. The graphene compound 583 present in the negative electrode 570a is, for example, a conductive material. It is preferable that it functions as such. In one embodiment of the present invention, the conductive material is activated by hydrogen bonding. Because it can adhere to the material, it is possible to create electrodes with high conductivity.

[0047] Various materials can be used as the first active material 581 and the second active material 582. The first active material 581 and the second active material 582 are surface layers which are particles according to one embodiment of the present invention. Particles having an oxygen-containing functional group or fluorine, or a surface with an oxygen-containing functional group or When using particles having a region terminated by a fluorine atom, the first active material 581 and The affinity between the second active material 582 and the graphene compound 583 was improved, as shown in Figures 1B and 3A. As shown, graphene compound 583 is located on the surface of the first active material 581, second active The first active material 58 covers, encloses, or clings to the substance 582. It can come into contact with 1. Graphene compound 583 is the first active material 581 and the second active material Because it can adhere to quality 582, it is possible to realize electrodes with high conductivity. The state of clinging to something can also be described as making close contact rather than just touching at a single point. It can be replaced. Alternatively, it can be rephrased as being in contact with the particle surface. Also, This can also be rephrased as being in surface contact with multiple particles. The first active material 581 and the The materials that can be used as the active material 582 in part 2 will be described later.

[0048] When using an active material 582 that exhibits a large volume change during charging and discharging, Next, we will explain using Figures 3B and 3C. Figure 3B shows the first active material 581 and the second active material It comprises quality 582 and graphene compound 583 as a sheet-like material, The rafen compound 583 affects the second active material 582 located on the surface of the first active material 581. The way in which the first active material 581 comes into contact with the other material, such as covering, enveloping, or clinging to it. This shows that the second active material 582 is composed of the first active material 581 and the graphene compound 583. Located between them, graphene compound 583 is the first active material 581 and the second active material 5 It can also be said that it is in contact with 82. The volume of the second active material 582 shown in Figure 3B. However, Figure 3C shows the case where the value increases due to charging or discharging. Graphene compound 58 3 surrounds the second active material 582, which is located on the surface of the first active material 581. Because it is in contact with the first active material 581 in a way that it clings to it, charging or discharging Even if the volume of the second active material 582 increases due to electricity, the second active material 58 Electrical contact between 2 and the first active material 581 can be maintained. Also, electrode collapse can be prevented. It can be suppressed.

[0049] Graphene compound 583 is used in active materials such as the first active material 581 and the second active material 582. When the material comes into contact in a clinging manner, the contact area between graphene compound 583 and the active material is large. This improves the conductivity of electrons moving through graphene compound 583. If the volume of the active material changes significantly, graphene compound 583 will adhere to the active material. By making close contact, it is possible to effectively prevent the active material from falling off. These effects can be even more pronounced when they are in close contact. Here, graphene compound 583 has pores large enough to pass Li ions, and the number of pores is It is desirable to have a sufficient amount of graphene compound 583 without interfering with its electronic conductivity.

[0050] The negative electrode active material layer 572a contains, in addition to graphene compound 583, carbon black and graphite. It can contain carbon-based materials such as carbon fiber and fullerene. For example, acetylene black (AB) can be used. Natural black is used as the graphite. Lead, artificial graphite such as mesocarbon microbeads, etc. can be used. The system material has high conductivity and can function as a conductive material in the active material layer. These carbon-based materials may function as active materials.

[0051] Examples of carbon fibers include mesophase pitch carbon fibers and isotropic pitch carbon fibers. Carbon fibers can be used. In addition, carbon nanofibers or Carbon nanotubes can be used, for example, in the gas phase. It can be produced using growth methods, etc.

[0052] Furthermore, the active material layer contains metal powders such as copper, nickel, aluminum, silver, and gold as conductive materials. Alternatively, it may contain metal fibers, conductive ceramic materials, etc.

[0053] The content of conductive material relative to the total amount of solids in the active material layer is 0.5 wt% to 10 wt%. This is preferable, and 0.5 wt% to 5 wt% is more preferable.

[0054] Unlike granular conductive materials such as carbon black that make point contact with the active material, graphene compounds Because it enables surface contact with low contact resistance, it requires less granular active material than ordinary conductive materials. The electrical conductivity between the material and the graphene compound can be improved. Therefore, the active material The ratio in the material layer can be increased. This increases the discharge capacity of the secondary battery. It can be made to happen.

[0055] Furthermore, the graphene compound according to one embodiment of the present invention has excellent lithium permeability, so secondary batteries This can increase the charge and discharge rate.

[0056] Particulate carbon-containing compounds such as carbon black and graphite, and carbon nanotubes Fibrous carbon-containing compounds such as these can easily enter tiny spaces. These tiny spaces are, for example, multiple spaces. This refers to the regions between active materials. Carbon-containing compounds that easily enter minute spaces and multiple particles By combining sheet-like carbon-containing compounds such as graphene, which can impart conductivity, By using it in this way, the electrode density can be increased, and a superior conductive path can be formed. Furthermore, by having an electrolyte 576 according to one aspect of the present invention, the operation of the secondary battery is stable. Qualitative accuracy can be improved. That is, a secondary battery according to one aspect of the present invention has an energy density of It combines height and stability, making it effective as a secondary battery for vehicles. Increasing the number of ponds increases the weight of the vehicle, which in turn increases the energy required to move it. Therefore, the driving range will also be shorter. By using high-density secondary batteries, the secondary batteries installed in the vehicle Even if the weight is the same, that is, even if the total weight of the vehicle is the same, to increase the driving range It is possible.

[0057] Furthermore, as the capacity of a vehicle's secondary battery increases, more power is required for charging, so for a short time... It is desirable to end the charging process at that point. Also, when the vehicle brakes are applied, power is temporarily generated. Then, in so-called regenerative charging, charging is performed under high-rate charging conditions. Therefore, good rate characteristics are required for secondary batteries used in vehicles.

[0058] By using the electrolyte 576 according to one aspect of the present invention, an automotive application having a wide operating temperature range is obtained. A secondary battery can be obtained.

[0059] Furthermore, a secondary battery according to one aspect of the present invention can be miniaturized due to its high energy density. Because of its high conductivity, rapid charging is also possible. Therefore, the configuration of a secondary battery according to one embodiment of the present invention is portable It is also effective on mobile information terminals.

[0060] The negative electrode active material layer 572a preferably has a binder (not shown). The binder is For example, the electrolyte 576 and the active material are bound or fixed together. The binder also binds the electrolyte 576 This involves binding carbon-based materials, active materials and carbon-based materials, multiple active materials to each other, multiple carbon-based materials, etc. It can be fixed in place.

[0061] As a binder, polystyrene, methyl polyacrylate, polymethyl methacrylate ( Methyl methacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol Polyethylene oxide (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide Polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, poly Isobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVD) F) Polyacrylonitrile (PAN), ethylene propylene diene polymer, polyacetic acid It is preferable to use materials such as vinyl or nitrocellulose.

[0062] Polyimides possess excellent thermal, mechanical, and chemical stability. When polyimide is used as the additive, a dehydration reaction and a cyclization (imidization) reaction are carried out. These reactions can be carried out, for example, by heat treatment. In an electrode according to one embodiment of the present invention... , graphene having an oxygen-containing functional group as a graphene compound, and poly as a binder When using mid, the heat treatment can also reduce the graphene compound. This allows for simplification of the process. Furthermore, due to its excellent heat resistance, it can withstand heating temperatures above 200°C, for example. Heat treatment can be performed at a temperature of 200°C or higher. This allows for a more complete reduction reaction of the graphene compound, thereby improving the conductivity of the electrode. It is possible.

[0063] Fluorine-containing polymer materials, specifically polyvinylidene fluoride ( Materials such as PVDF can be used. PVDF has a melting point in the range of 134°C to 169°C. It is a resin with excellent thermal stability.

[0064] Also, as a binder, styrene-butadiene rubber (SBR), styrene-isoprene- Styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propion It is preferable to use rubber materials such as lendiene copolymers. Also, as a binder, Fluorocarbon rubber can be used.

[0065] Furthermore, it is preferable to use a water-soluble polymer as the binder. As molecules, for example, polysaccharides can be used. As for polysaccharides, carboxymethyl Cholecellulose (CMC), methylcellulose, ethylcellulose, hydroxypropyl Cellulose derivatives such as cellulose, diacetylcellulose, and regenerated cellulose, or syrup Powders and other forms can be used. Furthermore, these water-soluble polymers can be used in combination with the aforementioned rubber materials. It is even preferable to use it in this way.

[0066] You may use a combination of several of the binders mentioned above.

[0067] Furthermore, graphene compound 583 is flexible, and the first active material 581 and the second active material It can cling to material 582 like natto (fermented soybeans). Also, for example, the first active material 581 The second active material 582 is added to soybeans, and the graphene compound 583 is added to a viscous component, such as polyglutamic acid. Each can be likened to tamic acid. Graphene compound 583 is used in the negative electrode active material layer 5 The electrolyte 576, multiple active materials, multiple carbon-based materials, etc. that 72a possesses are present between these materials. By arranging them in this way, not only is a good conductive path formed within the negative electrode active material layer 572a, but Furthermore, these materials can be bound or fixed using graphene compound 583. For example, multiple graphene compounds 583 form a three-dimensional network structure, with polygons arranged in a grid. The structure, for example, forms a honeycomb structure in which hexagons are arranged in a matrix, and electrolyte 5 is placed in the network. 76. By arranging multiple active materials, multiple carbon-based materials, etc., graphene Compound 583 forms a three-dimensional conductive path, and electrolyte 576 is removed from the current collector. This can be suppressed. Also, in the structure in which the above polygons are arranged, the number of sides of different sides Polygons may be arranged in a mixed pattern. Therefore, graphene compound 583 is active at the negative electrode. In the case where material layer 572a functions as both a conductive material and a binder... There is. Graphene compound 583 has holes with 9 or more membered rings, and even when covering the active material Since it does not inhibit the movement of Li ions, it is particularly suitable as a conductive material for use in the negative electrode active material layer 572a. preferable.

[0068] [Negative electrode active material] The first active material 581 and the second active material 582 have rounded shapes, angular shapes, It can have various shapes, such as the first active material 581 in the cross-section of the electrode. And the second active material 582 has various cross-sectional shapes such as circles, ellipses, curved figures, polygons, etc. It can have the following. For example, as shown in Figures 1B and 3A, the first active material 581 and The second active material 582 has a rounded cross-section, but the first active material 58 The cross-sections of the first and second active materials 582 may have corners. Also, some parts may be rounded, and some parts may be rounded. It may have corners.

[0069] An example of a negative electrode active material is described below.

[0070] Silicon can be used as the negative electrode active material. The negative electrode 570a is the second active material 5 It is preferable to use silicon-containing particles as 82.

[0071] Furthermore, the negative electrode active material of the second active material 582 is tin, gallium, and aluminum. Choose from germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. Metals or compounds having one or more elements can be used. Examples of alloy compounds using this include Mg2Si, Mg2Ge, Mg2Sn, and SnS 2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb 3. Examples include InSb and SbSn.

[0072] Furthermore, silicon contains impurity elements such as phosphorus, arsenic, boron, aluminum, and gallium. Materials with added and reduced resistance may be used. Alternatively, lithium-predoped silicon materials may be used. You may use a different material. Pre-doping methods include lithium fluoride, lithium carbonate, etc. and silicon Methods such as mixing and annealing, mechanical alloying of lithium metal and silicon, etc. There is a law. Also, after forming the first electrode using silicon as the active material, a second electrode such as lithium metal is formed. By combining with electrodes and undergoing a charge-discharge reaction, lithium is doped into the silicon of the first electrode. Then, using the doped first electrode, the counter electrode (for example, a pre-doped negative electrode) is used. A secondary battery may be manufactured by combining the positive electrode with the other electrodes.

[0073] For example, nanosilicon particles can be used as the second active material 582. The average diameter of the particles is, for example, preferably 5 nm or more and less than 1 μm, more preferably 10 nm. The wavelength is 300 nm or less, and more preferably 10 nm to 100 nm.

[0074] The nanosilicon particles may have a spherical shape or a flattened spherical shape. Often, they may also have a rectangular parallelepiped shape with rounded corners. Size of nanosilicon particles (particle diameter) ) For example, as D50 in laser diffraction particle size distribution measurement, preferably 5 nm to 1 μm Less than m, more preferably 10 nm to 300 nm, even more preferably 10 nm to 1 It is less than 00 nm. Here, D50 refers to the cumulative particle amount curve of the particle size distribution measurement results. The particle size when the cumulative amount accounts for 50% is the median. The determination is not limited to laser diffraction particle size distribution measurement, but also includes analysis using SEM or TEM. Alternatively, the major axis of the particle cross-section may be measured.

[0075] It is preferable that the nanosilicon particles have amorphous silicon. It is preferable that the nanosilicon particles have polycrystalline silicon. It is preferable that it has crystalline silicon. Also, the nanosilicon particles have a crystalline region, It may have amorphous regions.

[0076] For example, a material containing silicon is SiO x (x is preferably less than 2, and more preferably Materials with a ratio of 0.5 to 1.6 can be used.

[0077] For example, a silicon-containing material can be used in which multiple crystal grains are present within a single particle. This is possible. For example, a form in which one particle contains one or more silicon crystal grains. It can be used. In addition, one particle has silicon oxide surrounding the silicon crystal grain. It may have a silicon oxide. The silicon oxide may also be amorphous. These may be particles coated with graphene compound 583.

[0078] Furthermore, silicon-containing compounds include, for example, Li2SiO3 and Li4SiO4. Li2SiO3 and Li4SiO4 may each be crystalline. It may also be amorphous.

[0079] Analysis of silicon-containing compounds can be performed using NMR, XRD, Raman spectroscopy, SEM, TEM, and E This can be done using DX (Digital Transformation), etc.

[0080] The first active material 581 of the negative electrode 570a preferably contains graphite.

[0081] The first active material 581 is more preferably a material that exhibits small volume changes during charging and discharging. It's nice.

[0082] As a volume change of the first active material 581 associated with charging or discharging, When the minimum volume is set to 1, the maximum volume during charging or discharging must be 2 or less. Preferably, it is 1.5 or less, more preferably 1.1 or less. stomach.

[0083] The particle size of the first active material 581 is preferably larger than the particle size of the second active material 582. It's nice.

[0084] For example, in laser diffraction particle size distribution measurement, D50 of the first active material 581 is the second The D50 of the active material 582 is preferably 1.5 times or more but less than 1000 times, and preferably 2 times or more but less than 500 times. The lower is more preferable, and a ratio of 10 times to 100 times is even more preferable. Here, D50 refers to the particle size ratio. In the cumulative particle amount curve of the cloth measurement results, the particle size when the cumulative amount accounts for 50% is... This is the median. Note that particle size measurement is limited to laser diffraction particle size distribution measurement. If not determined, the diameter of the particle cross-section may be measured by analysis such as SEM or TEM.

[0085] Furthermore, as the first active material 581, for example, graphite and easily graphite, which exhibit small volume changes during charging and discharging, can be used. Graphite-forming carbon, non-graphitizing carbon, carbon nanotubes, carbon black, and graphene Carbon-based materials such as compound 583 can be used.

[0086] Furthermore, the first active material 581 may be, for example, titanium, niobium, tungsten, and molybdenum. An oxide having one or more elements selected from den can be used.

[0087] As the first active material 581, a combination of multiple metals, materials, compounds, etc. shown above is used. It is possible.

[0088] For example, the first active material 581 is SnO, SnO2, titanium dioxide (TiO2), etc. Titanium oxide (Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6) Niobium pentoxide (Nb2O5), tungsten oxide (WO2), molybdenum oxide (MoO2) 2) Oxides such as the above can be used.

[0089] Furthermore, a material that undergoes a conversion reaction can also be used as the first active material 581. For example, cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. Alternatively, a transition metal oxide that does not undergo an alloying reaction with lithium may be used as the first active material 581. Furthermore, materials that can cause a conversion reaction include Fe2O3, CuO, Cu2O, Oxides such as RuO2 and Cr2O3, CoS 0.89 , sulfides such as NiS and CuS, Zn3 Nitrides such as N2, Cu3N, Ge3N4, and phosphides such as NiP2, FeP2, and CoP3, Examples include fluorides such as FeF3 and BiF3. Note that the potential of the above fluorides is high, It may also be used as a positive electrode material.

[0090] [Negative electrode calculation 1] In one aspect of the present invention, graphite is used as the negative electrode 570a, and the second Regarding the case in which silicon is used as the active material 582, the first active material 581 and the second active material First-principles calculations were performed to determine the diffusion coefficient of lithium in quality 582.

[0091] Figure 4A shows graphite (Li 0.25 The crystal structure model used in the calculations for C6) is shown below. Figure 4B shows silicon (Li 1.25 The crystal structure model used in the calculations for Si is shown. They are doing it.

[0092] The first-principles electronic state calculation package VASP was used for the calculations. Regarding the specific calculation conditions... The conditions shown in Table 1 were used.

[0093] [Table 1]

[0094] Regarding the crystal structure model shown in Figure 4A and Figure 4B, after volume relaxation calculations at each temperature... We performed molecular dynamics (MD) calculations under constant volume conditions. The MD calculations were performed in multiple steps. The diffusion coefficient is derived from the relationship between the amount of lithium displacement at each step and the elapsed time. I took it out.

[0095] The results of the calculations shown in Figures 4A, 4B, and Table 1 are shown in Figure 5. As a result of the calculations, The study showed that the diffusion coefficient of lithium is higher in graphite than in lithium.

[0096] Furthermore, regarding the relationship between the oxidation-reduction potentials of graphite and silicon, graphite has a potential of 0.05V (vs. It is known that for Li, Si has a redox potential of 0.4V (vs. Li). It correlates with the voltage at which charging (lithium intake) begins, and lithium insertion during charging. Considering the priority, lithium is preferentially incorporated into Si, which has a high oxidation-reduction potential. It is thought that...

[0097] These calculation results for the diffusion coefficient shown in Figure 5, along with the relationship with the redox potential, are used to make an inference. As a result, in the initial stages of charging, lithium is preferentially incorporated into silicon due to the difference in oxidation-reduction potential. However, as charging progresses, the difference in lithium uptake rates gradually increases the size of the diffusion coefficient. There is a possibility that lithium uptake into graphite (which has a high uptake rate) will be prioritized. Therefore, when capacity limiting is performed in the negative electrode 570a of one aspect of the present invention, the first active The graphite in material 581 absorbs lithium up to near its theoretical capacity, and the second active material 582 It is presumed that the silicon will absorb the excess lithium. In other words, one aspect of the present invention In the negative electrode 570a, if capacity limiting is applied, the silicon of the second active material 582 The graphite of the first active material 581 is preferentially used for charging and discharging, rather than the condensate, and the effect of capacity limiting is This may primarily affect the silicon in the second active material, 582.

[0098] [Negative electrode calculation 2] Figure 6A shows a silicon crystal without lithium, while Figures 6B and 6C show a silicon crystal filled with lithium. This diagram shows the structure in the electrolyzed state (alloyed with Li).

[0099] Figure 6B shows the structure at Li / Si = 1.714, and the structure contains Si-Si bonds. It can be seen that a mixture remains. On the other hand, as shown in Figure 6C, the limit value at the theoretical capacity is Li / In the crystal structure at Si=4.4, the increased Li ratio results in Si-Si bonds in the structure. It can be seen that no compound exists. Silicon's crystal structure breaks down through repeated charging and discharging, and ammonia It is known that the process involves rufusification and thinning, but for example, when a secondary battery is fully charged... If the Si-Si bond shown in Figure 6B remains, it will persist even after repeated charging and discharging. It is considered highly likely that the structure will be maintained to a certain extent. Preferably, Li / shown in Figure 6B When used with a lithium ratio (molar ratio) of Si = 1.714 or less, good charging It may exhibit discharge cycle characteristics.

[0100] [Capacity limit of the negative electrode] In one aspect of the present invention, the negative electrode 570a is based on the theory of the first active material 581 and the second active material 582. It is preferable to use it as a secondary battery with a capacity less than its capacity. Capacity control of the negative electrode 570a For example, the theoretical capacity of the first active material 581 and the second active material 582, preferably In the case of a volume ratio of 50% or more but less than 100%, more preferably 70% or more but less than 90% This is preferable because it allows for the acquisition of a secondary battery with high charge / discharge capacity and good charge / discharge cycle characteristics.

[0101] [Method for fabricating the negative electrode] Figure 7 is a flowchart showing an example of a method for manufacturing a negative electrode 570a according to one aspect of the present invention.

[0102] First, in step S61, as the second active material 582, a particle having silicon is Prepare. For example, the silicon-containing particles are described above as the second active material 582. These particles can be used.

[0103] In step S62, prepare the solvent. Examples of solvents include water, methanol, and ethanol. Nol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), Either N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO) Alternatively, a mixture of two or more solutions can be used.

[0104] Next, in step S63, the silicon-containing particles prepared in step S61, The solvent prepared in step S62 is mixed with the mixture, and the mixture is recovered in step S64. In step S65, mixture E-1 is obtained. A kneader or the like can be used for mixing. For example, a rotary-orbit mixer can be used as a mixing machine.

[0105] Next, in step S72, as the first active material 581, particles having graphite are prepared. As the particles having graphite, for example, the particles described as the first active material 581 above can be used.

[0106] Next, in step S73, the mixture E-1 and the particles having graphite prepared in step S72 are mixed, in step S74 the mixture is recovered, and in step S75 the mixture E-2 is obtained. For the mixing, a kneader or the like can be used. As the kneader, for example, a planetary mixer or the like can be used.

[0107] Next, in step S80, a graphene compound 583 is prepared.

[0108] Next, in step S81, the mixture E-2 and the graphene compound 583 prepared in step S80 are mixed, and in step S82 the mixture is recovered. The recovered mixture preferably has a high viscosity. Due to the high viscosity of the mixture, in the next step S83, solid kneading (kneading at high viscosity) can be performed. The mixture is preferably in a state of high viscosity. Due to the high viscosity of the mixture, in the next step S83, solid kneading (kneading at high viscosity) can be performed.

[0109] Next, in step S83, solid kneading is performed. The solid kneading can be performed, for example, using a spatula or the like. By performing the solid kneading, a mixture in which the particles having silicon and the graphene compound 583 are well mixed and the dispersibility of the graphene compound 583 is excellent can be formed.

[0110] Next, in step S84, a solvent is added to the solid kneaded mixture and mixing is performed. For the mixing, a kneader or the like can be used, for example. The mixture after mixing is recovered in step S85. ​​​​​​​​​​ To collect.

[0111] The mixture recovered in step S85 is subjected to the steps S83 to S85. It is preferable to repeat the process n times. n is, for example, a natural number between 2 and 10. Furthermore, in step S83, if the mixture is dry, add the solvent. It is preferable to do so. On the other hand, if too much solvent is added, the viscosity will decrease and the effect of solid kneading will be reduced. To lower.

[0112] After repeating steps S83 to S85 n times, obtain mixture E-3 (step (P S86).

[0113] Next, in step S87, prepare the binder. The binder is as described above. Any material can be used, and polyimide is particularly preferred. Note that in step S8 In step 7, a precursor of the material to be used as a binder may be prepared. For example, poly Prepare the imide precursor.

[0114] Next, in step S88, the mixture E-3 and the binder prepared in step S87 Mix and . Next, in step S89, adjust the viscosity. Specifically, for example Then, prepare a solvent of the same type as the one prepared in step S62, and in step S88... Add to the mixture obtained. By adjusting the viscosity, for example, in step S97 In some cases, the thickness, density, etc., of the electrodes obtained can be adjusted.

[0115] Next, the solvent is added to the mixture whose viscosity was adjusted in step S89, and then in step S9 Mix at step S91 to obtain mixture E-4 (step S9 2). The mixture E-4 obtained in step S92 is, for example, called a slurry.

[0116] Next, a current collector is prepared in step S93.

[0117] Next, in step S94, the mixture E-4 is applied onto the current collector prepared in step S93. For the application, a slot die method, gravure, blade method, and a combined method thereof can be used. Also, a continuous coater or the like may be used for the coating. [[ID=I4]]

[0118] Next, in step S95, the first heating is performed. By the first heating, the solvent volatilizes. The first heating is preferably performed within a temperature range of 40°C or higher and 200°C or lower, more preferably 50°C or higher and 150°C or lower. Note that the first heating may be referred to as drying. <000095J>

[0119] The first heating can be performed, for example, by heat treatment on a hot plate in an air atmosphere under conditions of 30°C or higher and 70°C or lower for 10 minutes or more, and then, for example, by heat treatment in a reduced pressure environment under conditions of room temperature or higher and 100°C or lower for 1 hour or more and 10 hours or less.

[0120]

[0121] Alternatively, heat treatment may be performed using a drying oven or the like. When using a drying oven, for example, heat treatment may be performed at a temperature of 30°C or higher and 120°C or lower for 30 seconds or more and 2 hours or less. Alternatively, the temperature may be increased stepwise. For example, after heat treatment at 60°C or lower for 10 minutes or less, heat treatment may be further performed at a temperature of 65°C or higher for 1 minute or more.

[0122] Next, in step S96, the second heating is performed. Polyimide is used as the binder. In this case, it is preferable that a cycloaddition reaction of the polyimide occurs by the second heating. Furthermore, a dehydration reaction of the polyimide may occur due to the second heating. Alternatively, the first heating Heat can cause a dehydration reaction of polyimide. Also, in the first heating, polyimide A cyclization reaction of mid may occur. Also, in the second heating, graphene compound 583 It is preferable that a reduction reaction occurs. The second heating process is referred to as imidation heat treatment or reduction heat treatment. This is sometimes called processing or thermal reduction processing.

[0123] Furthermore, by performing a pressing process before the second heating, the electrode density can be increased without degrading the battery characteristics. It is preferable to perform the press treatment before step S96, as this allows for improvement.

[0124] The second heating is performed at a temperature of 150°C to 500°C, preferably 200°C to 450°C. It is best to do this within a certain range.

[0125] The second heating is performed, for example, under conditions of 200°C to 450°C for 1 to 10 hours. If performed under reduced pressure below 0 Pa, or under an inert atmosphere such as nitrogen or argon good.

[0126] In step S97, a negative electrode 570a is obtained, which has an active material layer provided on the current collector.

[0127] The thickness of the active material layer formed in this way is preferably, for example, 5 μm to 300 μm. More preferably, the thickness should be between 10 μm and 150 μm. Also, the active material of the active material layer The load amount is preferably, for example, 2 mg / cm³. 2 More than 50mg / cm 2 The following is acceptable.

[0128] The active material layer may be formed on both sides of the current collector, or on only one side. Alternatively, it may partially have regions where active material layers are formed on both sides.

[0129] After the solvent has evaporated from the active material layer, a compression method such as a roll press or a flat plate press is applied. Further pressing may be performed. Heat may be applied during the pressing process.

[0130] [Positive electrode] The positive electrode 570b is a positive electrode formed in contact with the positive electrode current collector 571b and the positive electrode current collector 571b. It includes at least an active material layer 572b. Details of the positive electrode 570b will be described in subsequent embodiments. I will explain it here.

[0131] [Conductive material] Conductive materials, also called conductivity imparters or conductivity enhancers, are made of carbon materials. By attaching a conductive agent between multiple active materials, they become electrically connected to each other, increasing their conductivity. Note that "adhesion" refers only to the physical close contact between the active material and the conductive agent. There is no covalent bond, and when bonding occurs, when bonding occurs by van der Waals forces, the surface of the active material When a conductive agent covers a portion of a surface, when the conductive agent becomes embedded in the surface irregularities of the active material, when they come into contact with each other This concept includes cases where devices are electrically connected even if they are not physically connected.

[0132] Examples of conductive materials include acetylene black and furnace black. Graphite such as Bombrak, artificial graphite, and natural graphite, carbon nanofibers, and Carbon fibers such as carbon nanotubes, and graphene compound 583, either one One or more types may be used.

[0133] As the positive electrode 570b of the secondary battery, a positive electrode current collector 571b such as metal foil and an active material are solidified. A binder (resin) is mixed in to make it adhere. The binder is also called a binding agent. Inda is a polymer material, and when a large amount of binder is included, the active material in the positive electrode active material layer 572b As the proportion of the material decreases, the discharge capacity of the secondary battery decreases. Therefore, the amount of binder is kept to a minimum. It is being mixed in.

[0134] Graphene possesses remarkable electrical, mechanical, and chemical properties, therefore, Carbon is expected to have various applications, such as field-effect transistors and solar cells. It is a material.

[0135] Furthermore, carbon fibers can be used as conductive materials. For example, mesophase pitch carbon Carbon fibers such as fibrous materials and isotropic pitch carbon fibers can be used. Carbon nanofibers or carbon nanotubes can be used. Bonn nanotubes can be fabricated, for example, by vapor phase growth.

[0136] [Graphene compounds] In this specification, graphene compound 583 refers to graphene, multilayer graphene, and multilayer graphene. Graphene, graphene oxide, multilayer graphene oxide, multi-graphene oxide, reduced Graphene oxide, reduced multilayer graphene oxide, reduced multilayer graphene oxide, Includes graphene quantum dots, etc. Graphene compound 583 is a flat, plate-shaped compound containing carbon. This refers to a material having a shape such as a ring and a two-dimensional structure formed of a six-membered carbon ring. The two-dimensional structure formed by the six-membered ring can also be called a carbon sheet. Graphene compound 58 Compound 3 may have an oxygen-containing functional group. Also, graphene compound 583 has a bent shape. It is preferable to do so. Also, graphene compound 583 rolls up into carbon nanofibers. It's fine if it's like that.

[0137] In this specification, graphene oxide refers, for example, to a material having carbon and oxygen, and in a sheet-like form. It refers to a substance that has functional groups, particularly epoxy groups, carboxyl groups, or hydroxyl groups. .

[0138] In this specification, reduced graphene oxide refers to, for example, a substance having carbon and oxygen, and This refers to a structure that has a T-shape and a two-dimensional structure formed from a six-membered carbon ring. It could be said that a single reduced graphene oxide sheet functions, but multiple sheets are stacked together. It may be reduced graphene oxide has a carbon concentration greater than 80 atomic%. The material has a portion where the oxygen concentration is between 2 atomic% and 15 atomic%. This is preferable. By using such carbon and oxygen concentrations, a small amount of conductive material can be used. It can function as an electrical material. Furthermore, reduced graphene oxide exhibits a Raman spectrum. In such cases, the intensity ratio of the G band to the D band, G / D, is preferably 1 or greater. Reduced graphene oxide, which has a high strength ratio, functions as a highly conductive material even in small amounts. It is possible.

[0139] By reducing graphene oxide, pores can be created in the reduced graphene oxide. It is sometimes possible.

[0140] Furthermore, as a graphene compound, a material in which the ends of graphene are terminated with fluorine is used. That's good too.

[0141] In the longitudinal section of the active material layer, a sheet-like gradient is found in the internal region of the active material layer, which is roughly uniform. Fen compound 583 is dispersed. Multiple graphene compounds partially contain multiple granular active materials. Because it is formed to cover or adhere to the surface of multiple granular active materials. They are in surface contact with each other.

[0142] Here, multiple graphene compounds 583 bond to each other, forming a network of graphene Forming a graphene compound sheet (hereinafter referred to as graphene compound net or graphene net) It is possible. When the active material is covered with a graphene net, the graphene net can be used to coat the active material. It can also function as a binder that combines different materials. Therefore, the amount of binder is small. Because it can be used or not used, it accounts for the electrode volume and electrode weight. This allows for an improvement in the ratio of active materials. In other words, it increases the charge and discharge capacity of secondary batteries. It is possible.

[0143] Here, graphene oxide is used as graphene compound 583 and mixed with the active material to form the active material It is preferable to reduce the graphene oxide after forming the layer that will become the matrix. In other words, after completion The material layer preferably has reduced graphene oxide. Graphene compound 583 When forming the active material layer, graphene oxide, which has extremely high dispersibility in polar solvents, is used. This allows the graphene compound 583 to be dispersed approximately uniformly within the internal region of the active material layer. It can be made to happen.

[0144] A dispersion in which graphene oxide is dispersed in a solvent in a generally uniform manner is applied to a current collector, and the solvent In the active material layer produced by volatilizing and then reducing graphene oxide, The graphene compound 583 present in the material layer partially overlaps. In this way, the reduced The graphene oxide particles are dispersed to the extent that they are in surface contact with each other, creating a three-dimensional conductive path. It can be formed. Furthermore, the reduction of graphene oxide can be carried out, for example, by heat treatment. Alternatively, a reducing agent may be used.

[0145] Furthermore, by pre-covering the surface of the active material with a graphene compound, a conductive coating is formed on the surface of the active material. By forming it on a surface and further electrically connecting the active materials with a graphene compound, a conductive path is created. It can also be formed.

[0146] In one embodiment of the present invention, the graphene compound 583 preferably has pores in a portion of the carbon sheet. It is so. In graphene compound 583 according to one embodiment of the present invention, a part of the carbon sheet contains lithium By providing pores through which carrier ions such as mu ions can pass, graphene compounds On the surface of the active material covered with substance 583, the insertion and removal of carrier ions becomes easier, The rate characteristics of the next battery can be improved. The holes provided in a part of the carbon sheet are voids. These are sometimes called defects or voids.

[0147] Graphene compound 583 according to one aspect of the present invention comprises a plurality of carbon atoms and one or more fluorine atoms It is preferable that the pores are provided by the above. Furthermore, the plurality of carbon atoms are bonded in a ring shape. It is preferable that one or more of the cyclically bonded carbon atoms are connected by the fluorine atom It is preferable to terminate the line. Fluorine has high electronegativity and is prone to becoming negatively charged. When charged lithium ions approach, an interaction occurs, the energy stabilizes, and The barrier energy for thium ions to pass through the pores can be lowered. Therefore, graph Because the pores of compound 583 contain fluorine, lithium iodine is present even in small pores. The goal is to create a graphene compound 583 that allows for easy passage of particles and possesses excellent conductivity. Yes, it is possible. Furthermore, one or more of the multiple carbon atoms bonded in a ring are terminated by hydrogen atoms. That's fine.

[0148] Figures 8A and 8B show an example of the structure of the porous graphene compound 583. The porosity-containing graphene compound 583 shown in A and Figure 8B is a porosity-containing graphene, It is also called reduced graphene with pores.

[0149] The structure shown in Figure 8A has a 22-membered ring, and of the carbon atoms constituting the 22-membered ring, 8 carbon atoms are Each is terminated by hydrogen. Also, in graphene compound 583, the two linked The structure is formed by removing the six-membered ring and terminating the carbon atom that was bonded to the removed six-membered ring with a hydrogen atom. One could also say that.

[0150] The structure shown in Figure 8B has a 22-membered ring, and of the carbon atoms constituting the 22-membered ring, 8 carbon capsules Furthermore, six carbon atoms are terminated by hydrogen atoms, and two carbon atoms are terminated by fluorine atoms. In the rafen compound 583, the two linked 6-membered rings are removed, and the removed 6-membered ring It can also be said that it has a structure in which the carbon atom bonded to it is terminated with hydrogen or fluorine.

[0151] Hydroxyl-terminated silicon has hydrogen from the hydroxyl group on the silicon surface, Hydrogen atoms or fluorine atoms in graphene compound 583 Because hydrogen bonds are formed between atoms, silicon terminated with a hydroxyl group has pores. It is thought that there is a strong interaction with graphene compound 583, which has [a certain characteristic].

[0152] Graphene compound 583 has fluorine in addition to hydrogen, which allows the hydroxyl group to act as an acid. In addition to the hydrogen bonds between the elementary atoms and the hydrogen atoms of graphene compound 583, the hydroxyl group A hydrogen bond is also formed between the hydrogen atom and the fluorine atom of graphene compound 583, thus protecting silicon. It is thought that the interaction between the particles and graphene compound 583 becomes stronger and more stable. It can be obtained.

[0153] If graphene compound 583 has pores, for example, in Raman spectroscopy mapping measurements... Furthermore, it may be possible to observe spectra based on features originating from the pores. It may be possible to observe the bonds, functional groups, etc., using ToF-SIMS. Furthermore, TEM observation is also possible. This may allow for analysis of the vicinity of the hole, the area surrounding the hole, etc.

[0154] [Binder] In this specification, the term "binder" refers solely to a material used to bind active materials, conductive materials, etc., onto a current collector. This refers to the polymer compounds that are mixed together. For example, polyvinylidene fluoride (PVDF) and styrene. -Butadiene rubber (SBR), styrene-isoprene-styrene rubber, butadiene rubber, Rubber materials such as ethylene-propylene-diene copolymers, fluororubber, polystyrene, Polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyiso This refers to materials such as butylene and ethylene propylene diene polymers.

[0155] Since lithium-ion conductive polymers are polymer compounds, they must be thoroughly mixed before being used in the active material layer. This makes it possible to bond the active material and conductive material onto the current collector. Electrodes can be fabricated without using binders. Binders are materials that do not contribute to the charge-discharge reaction. Therefore, the less binder there is, the more materials that contribute to charging and discharging, such as active materials and electrolytes. Yes, it is possible. Therefore, it is possible to create a secondary battery with improved discharge capacity or cycle characteristics. ru.

[0156] To make electrolyte 576 an electrolyte layer with little or no organic solvent, It is preferable that it be dried. In this specification, it is preferable that it be dried under reduced pressure at 90°C for 1 hour. If the weight change of the electrolyte layer is within 5%, it is considered to be sufficiently dried.

[0157] Furthermore, the lithium-ion conductive polymer, lithium salt, binder and the secondary battery contain Nuclear magnetic resonance (NMR), for example, can be used to identify materials such as additives. Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), time-of-flight secondary ion mass spectrometry Methods of analysis (TOF-SIMS), gas chromatography-mass spectrometry (GC / MS), pyrolysis gas Chromatography-mass spectrometry (Py-GC / MS), liquid chromatography-mass spectrometry ( The results of analyses such as LC / MS may also be used as a basis for judgment. The active material layer is suspended in a solvent and It is preferable to separate the substance from other materials before subjecting them to analysis such as NMR.

[0158] Furthermore, in each of the above configurations, a solid electrolyte material is added to the negative electrode 570a to provide flame retardancy. The performance may be improved. It is preferable to use an oxide-based solid electrolyte as the solid electrolyte material. .

[0159] As the oxide-based solid electrolyte, LiPON, Li2O, Li2CO3, Li2MoO4 , Li3PO4, Li3VO4, Li4SiO4, LLT (La 2 / 3-x Li 3x Ti O3), LLZ (Li7La3Zr2O 12 ), etc., lithium composite oxides and lithium oxide materials can be mentioned.

[0160] LLZ is a garnet-type oxide containing Li, La, and Zr, and may also be a compound containing Al, Ga, or Ta.

[0161] Also, a polymer-based solid electrolyte such as PEO (polyethylene oxide) formed by a coating method or the like may be used. Since such a polymer-based solid electrolyte can also function as a binder, when using a polymer-based solid electrolyte, the components of the electrode can be reduced, and the manufacturing cost can also be reduced.

[0162] [Current collector] As the positive electrode current collector 571b and the negative electrode current collector 571a, metals such as stainless steel, gold, platinum, zinc, iron, copper, aluminum, titanium, etc., and alloys thereof, which have high conductivity and do not alloy with carrier ions such as lithium , can be used. Also, an aluminum alloy added with an element for improving heat resistance such as silicon, titanium, neodymium, scandium, molybdenum, etc. can be used. Also, it may be formed of a metal element that reacts with silicon to form a silicide. As the metal element that reacts with silicon to form a silicide, there are zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molyb denum, tungsten, cobalt, nickel, etc. The current collector can be in the form of a sheet, a net, a punch ed, etc. Shapes such as ring metal shape, expanded metal shape, etc. can be appropriately used. The current collector preferably has a thickness of 10 μm or more and 30 μm or less.

[0163] Note that the negative electrode current collector 571a preferably uses a material that does not alloy with carrier ions such as lithium.

[0164] A titanium compound may be provided by laminating on the above-described metal element as the current collector. As the titanium compound, for example, titanium nitride, titanium oxide, titanium oxynitride in which part of nitrogen is replaced by oxygen (TiO x N y , 0 < x < 2, 0 < y < 1), and titanium oxide in which part of oxygen is replaced by nitrogen, one selected therefrom, or two or more thereof may be mixed or laminated and used. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation. By providing the titanium compound on the surface of the current collector, for example, the reaction between the material of the active material layer formed on the current collector and the metal is suppressed. When the active material layer contains a compound having oxygen, the oxidation reaction between the metal element and oxygen can be suppressed. For example, when aluminum is used as the current collector and the active material layer is formed using graphene oxide described later, there is concern about the oxidation reaction between the oxygen of graphene oxide and aluminum. In such a case, by providing a titanium compound on aluminum, the oxidation reaction between the current collector and graphene oxide can be suppressed.

[0165] [Separator] A separator is disposed between the positive electrode 570b and the negative electrode 570a. As the separator, for example, fibers having cellulose such as paper, non-woven fabric, glass fiber, ceramics, or ​​​​​​​​​​These are nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), and polyester. Using synthetic fibers made of acrylic, polyolefin, polyurethane, etc. This is possible. The separator is processed into a bag shape, and either the positive electrode 570b or the negative electrode 570a is used. It is preferable to arrange them so as to enclose one side.

[0166] The separator has pores with a diameter of approximately 20 nm, preferably with a diameter of 6.5 nm or larger. It is a porous material having pores, more preferably pores with a diameter of at least 2 nm. In the case of semi-solid secondary batteries, the separator can be omitted.

[0167] The separator may have a multilayer structure. For example, an organic material such as polypropylene or polyethylene. The material film contains ceramic-based materials, fluorine-based materials, polyamide-based materials, or a combination thereof. Mixtures and other materials can be coated onto it. Examples of ceramic materials include aluminum oxide. Aluminum particles, silicon oxide particles, etc. can be used. Examples of fluorine-based materials include PVDF, polytetrafluoroethylene, etc. can be used. Polyamide materials and For example, nylon, aramid (meta-aramid, para-aramid), etc. can be used. It is possible.

[0168] Coating with ceramic materials improves oxidation resistance, thus preventing separation during high-voltage charging and discharging. This can suppress the degradation of the data and improve the reliability of secondary batteries. Furthermore, fluorine-based materials... Coating the electrode makes it easier for the separator and electrode to adhere to each other, which can improve the output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, thus improving the heat resistance of secondary batteries. Safety can be improved.

[0169] For example, a mixture of aluminum oxide and aramid material is applied to both sides of a polypropylene film. It may also be done. In addition, the surface of the polypropylene film that is in contact with the positive electrode 570b may be treated with an oxide coating. A mixed material of aluminum and aramid is coated, and a fluorine-based material is applied to the surface in contact with the negative electrode 570a. You may wear a coat.

[0170] Using a multilayer separator ensures the safety of secondary batteries even with a thin overall separator. Because this can be maintained, the capacity per unit volume of the secondary battery can be increased.

[0171] [Electrolyte] When using liquid electrolyte 576 in a secondary battery, for example, if ethylene carbonate is used as the electrolyte 576... Carbonate (EC), propylene carbonate (PC), butylene carbonate, chloro Ethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone Dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl Carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, Ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4 -Dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether Methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfol One of the following, such as sultone, or any combination and ratio of two or more of these. It can be used as a percentage.

[0172] Furthermore, as the solvent for electrolyte 576, an ionic liquid (molten at room temperature) that is flame-retardant and non-volatile is used. By using one or more salts, the internal region of the secondary battery may be short-circuited or overcharged, causing internal damage. Even if the temperature rises, it can prevent secondary batteries from rupturing or catching fire. (Ionic liquid) It consists of cations and anions, and includes organic cations and anions. And, quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as thion, as well as imidazolium cations, and pyridin Examples include aromatic cations such as um cations. Also, monovalent amides can be used as anions. Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Anions of tetrafluoroborate, perfluoroalkyl volate Toanions, hexafluorophosphate anions, or perfluoroalkyl phosphates Examples include ether anions.

[0173] In particular, in a secondary battery according to one aspect of the present invention, the second active material 582 of the negative electrode 570a When using silicon, it is preferable to use a liquid electrolyte 576 that contains an ionic liquid. It seems so.

[0174] A secondary battery according to one aspect of the present invention is, for example, a battery containing lithium ions, sodium ions, and potassium ions. Alkali metal ions such as lium ions, as well as calcium ions, strontium ions Alkaline earth metals such as barium ions, beryllium ions, and magnesium ions. It has one or more of the group ions as carrier ions.

[0175] When lithium ions are used as carrier ions, for example, the electrolyte is a lithium salt. Includes lithium salts such as LiPF6, LiClO4, LiAsF6, and LiBF4. , LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl1 0, Li2B 12 Cl 12 , LiCF3SO3, LiC4F9SO3, LiC(CF3S O2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9 SO2)(CF3SO2), LiN(C2F5SO2)2, etc. can be used.

[0176] Furthermore, the electrolyte preferably contains fluorine. For example, a fluorine-containing electrolyte is fluorine An electrolyte comprising one or more cyclic carbonates and lithium ions is used. It is possible. Fluorinated cyclic carbonates improve flammability and lithium ion secondary This can improve battery safety.

[0177] As a fluorinated cyclic carbonate, fluorinated ethylene carbonate, for example, monofluorinated ethylene carbonate, Fluoroethylene carbonate (fluoroethylene carbonate, FEC, F1EC), difluoroethylene Lentinum carbonate (DFEC, F2EC), trifluoroethylene carbonate (F3E C) Tetrafluoroethylene carbonate (F4EC), etc., can be used. Oh, DFEC has isomers such as cis-4,5 and trans-4,5. , lithium ions are solvated using one or more fluorinated cyclic carbonates. Therefore, transporting the electrolyte within the electrodes during charging and discharging is important for operation at low temperatures. Therefore, fluorinated cyclic carbonate is not used as a small amount of additive, but rather during the charging and discharging of lithium. By contributing to ion transport, operation at low temperatures becomes possible. Lithium ions in secondary batteries ON moves in clusters of several to several dozen units.

[0178] By using fluorinated cyclic carbonates as the electrolyte, the solvent within the electrolyte contained in the electrode The energy required for desolvation when the lithium ions in the mixture enter the active material particles is reduced. This desolvation energy can be reduced, allowing lithium to operate even in the low-temperature range. The ON ions become easier to insert into or detach from the active material particles. Note that lithium ions are in a solvated state. While they may move in their original state, a hopping phenomenon occurs where the coordinating solvent molecules are replaced. In some cases, lithium ions become more easily desolvated, and their movement due to the hopping phenomenon occurs. This can make it cheaper and easier for lithium ions to move. The decomposition products of the electrolyte adhere to the surface of the active material, causing degradation of the secondary battery. There is a concern about this. However, if the electrolyte contains fluorine, the electrolyte will be fluid. Therefore, the decomposition products of the electrolyte become less likely to adhere to the surface of the active material. This reduces the degradation of the secondary battery. It can be suppressed.

[0179] Solvated lithium ions form multiple clusters in the electrolyte, and at the negative electrode 570 It may move within a, between the positive electrode 570b and the negative electrode 570a, within the positive electrode 570b, etc.

[0180] In this specification, electrolytes are a general term that includes solid, liquid, or semi-solid materials. .

[0181] Degradation is likely to occur at interfaces within secondary batteries, such as the interface between the active material and the electrolyte. In one embodiment of a secondary battery, by having an electrolyte containing fluorine, the active material and the electrolyte To prevent degradation that can occur at the interface with the substance, typically the alteration of the electrolyte or the increase in the viscosity of the electrolyte. This can be done. In addition, for electrolytes containing fluorine, a binder or graphene compound can be used. The configuration may be such that it clings to or holds the material. By using this configuration, electrolysis It is possible to maintain a state in which the viscosity of the substance is reduced, or in other words, to maintain a fluid state of the electrolyte. This can improve the reliability of secondary batteries. DFEC, which has two fluorine atoms bonded together, is a type of fluorine compound. And F4EC, which has four fluorine atoms bonded together, has a higher viscosity compared to FEC, which has one fluorine atom bonded together. The viscosity is low and the material is fluid, resulting in a weak coordination bond with lithium. Therefore, the viscosity of the active material particles is low. This reduces the adhesion of highly viscous decomposition products to the active material particles. When lithium ions adhere to or cling to the active material particles, it becomes difficult for them to move at the interface between the particles. Fluorine-containing electrolytes, upon solvation, affect the surface of the active material (positive electrode active material or negative electrode active material). It reduces the formation of decomposition products that adhere to the material. Furthermore, by using an electrolyte containing fluorine, the decomposition By preventing substances from adhering to the surface, the formation and growth of dendrites can be prevented.

[0182] Another characteristic is that it uses electrolytes containing fluorine as its main component. The electrolyte content is 5% by volume or more, 10% by volume or more, preferably 30% by volume or more, up to 100 volumes. It should be less than or equal to %.

[0183] In this specification, the main component of the electrolyte is defined as 5% or more by volume of the total electrolyte of the secondary battery. This refers to the fact that... Also, the term "more than 5 volume percent of the total electrolyte of the secondary battery" here refers to the secondary battery... This refers to the proportion of the total electrolyte measured during manufacturing. It also refers to the proportion of the electrolyte after the secondary battery is manufactured. When decomposing the electrolyte, quantify the proportion of each type of electrolyte present. It is difficult to determine whether a particular organic compound makes up 5% or more of the total electrolyte by volume. It can be determined.

[0184] By using an electrolyte containing fluorine, a wide temperature range is achieved, specifically, from -40°C upwards to 15°C. It is possible to realize a secondary battery that can operate at temperatures below 0°C, preferably between -40°C and 85°C. Cut.

[0185] Furthermore, the electrolytes include vinylene carbonate, propanesultone (PS), and tert-butyl. Benzene (TBB), lithium bis(oxalate)borate (LiBOB), and also sucrose Additives such as dinitrile compounds like cinonitrile and adiponitrile may be added. The concentration of the additive should be, for example, 0.1% by volume or more and less than 5% by volume relative to the total electrolyte.

[0186] In addition to the above, electrolytes include γ-butyrolactone, acetonitrile, dimethoxyethane, It may contain one or more aprotic organic solvents such as tetrahydrofuran.

[0187] Furthermore, the presence of a polymer material in which the electrolyte gels enhances safety against leakage, etc. Okay. Typical examples of polymer materials that gel include silicone gel, acrylic gel, and acrylic gel. Lilonitrile gel, polyethylene oxide gel, polypropylene oxide gel, Examples include gels made from fluorine-based polymers.

[0188] Examples of polymer materials include polyalkylenes such as polyethylene oxide (PEO). Polymers having an oxide structure, PVDF, and polyacrylonitrile, etc., and the Copolymers containing these can be used. For example, PVDF and hexafluoropropylene PVDF-HFP, a copolymer of (HFP), can be used. The polymer may have a porous structure.

[0189] Furthermore, the above configuration is an example of a secondary battery using a liquid electrolyte, but it is not particularly limited to such configurations. For example, semi-solid-state batteries and all-solid-state batteries can also be fabricated.

[0190] In this specification, the positive electrode applies to both secondary batteries using a liquid electrolyte and semi-solid batteries. The layer placed between 570b and the negative electrode 570a will be called the electrolyte layer. The electrolyte layer is a layer formed by film deposition, and can be distinguished from a liquid electrolyte layer.

[0191] Furthermore, in this specification, a semi-solid battery refers to an electrolyte layer, a positive electrode 570b, and a negative electrode 570a. This refers to a battery having at least one semi-solid material. Here, "semi-solid" refers to the ratio of solid material. It does not mean that it is 50%. A semi-solid is a solid that has properties of a solid such as small volume change. This means that while possessing certain properties, it also has some liquid-like characteristics, such as flexibility. It can be a single material or multiple materials, as long as these properties are satisfied. For example, a liquid material The material may also be impregnated into a porous solid material.

[0192] Furthermore, in this specification, a polymer electrolyte secondary battery refers to a positive electrode 570b and a negative electrode 570a This refers to a secondary battery having a polymer in the electrolyte layer between the batteries. Polymer electrolyte secondary batteries are dry This includes (or intrinsic) polymer electrolyte batteries and polymer gel electrolyte batteries.

[0193] Electrolyte 576 comprises a lithium-ion conductive polymer and a lithium salt.

[0194] In this specification, a lithium-ion conductive polymer refers to a cation conductive polymer such as lithium. It is a polymer that has properties. More specifically, it is a polymer having polar groups to which cations can coordinate. It is a compound. Polar groups include ether groups, ester groups, nitrile groups, and carbonyl groups. It is preferable that the material contains siloxanes, etc.

[0195] Examples of lithium-ion conductive polymers include polyethylene oxide (PEO), Derivatives having polyethylene oxide as the main chain, polypropylene oxide, polyacrylic Polymethacrylates, polysyl esters, polysiloxanes, polyphosphazenes, etc. are used. It is possible to be there.

[0196] The lithium-ion conductive polymer may be branched or crosslinked. It may also be a polymer. The molecular weight is preferably, for example, 10,000 or more, and preferably 100,000 or more. It is preferable to have a certain state.

[0197] Lithium-ion conductive polymers exhibit partial motion (also called segmental motion) of polymer chains. Lithium ions move while changing the polar groups with which they interact. For example, PEO Then, the lithium ions change the oxygen they interact with through the segmental motion of the ether chain. It moves. The temperature is close to the melting or softening point of the lithium-ion conductive polymer, or When the temperature is high, the crystalline region dissolves and the amorphous region increases, and the movement of the ether chains becomes more active. Therefore, the ionic conductivity increases. For this reason, PEO is used as a lithium ion conductive polymer. When using this product, it is preferable to perform charging and discharging at temperatures above 60°C.

[0198] Shannon's ionic radius (Shannon et al., Acta A 32(19) According to 76) 751.), the radius of a monovalent lithium ion is 0.0590 when it is 4-coordinate. The wavelength is 0.076 nm for 6-coordinate systems and 0.092 nm for 8-coordinate systems. Also, divalent acids The radius of the elementary ion is 0.135 nm for 2-coordinate systems, 0.136 nm for 3-coordinate systems, and 4-coordinate systems. When it is 0.138 nm, when it is 6-coordinate it is 0.140 nm, and when it is 8-coordinate it is 0.142 nm. The distance between polar groups in adjacent lithium-ion conductive polymer chains is as described above. Lithium ions and anions from polar groups exist stably while maintaining their ionic radius. It is preferable that the distance is greater than the distance at which it can be made, and that the interaction between the lithium ion and the polar group is sufficient. It is preferable that this is the distance at which the motion occurs. However, as mentioned above, segment motion occurs, It is not necessary to maintain a constant distance at all times. The lithium ions should pass through at an appropriate distance. It would be nice to have.

[0199] Furthermore, lithium salts include, for example, lithium along with phosphorus, fluorine, nitrogen, sulfur, oxygen, Having at least one of chlorine, arsenic, boron, aluminum, bromine, and iodine. Compounds can be used. For example, LiPF6, LiN(FSO2)2(lithium bicarbonate). Su(fluorosulfonyl)imide, LiFSI, LiClO4, LiAsF6, LiB F4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 C l 10 Li2B 12 Cl 12 , LiCF3SO3, LiC4F9SO3, LiC(CF 3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2 (Lithium Bis (Trifluoromethanesulfonyl)imide (LiTFSA), LiN(C4F9SO2) (CF3SO2), LiN(C2F5SO2)2, Lithium Bis(Oxalate) Volley One type of lithium salt such as (LiBOB), or any combination of two or more of these. It can be used in terms of ratios and proportions.

[0200] In particular, using LiFSI is preferable because it provides good low-temperature characteristics. TFSA is less reactive with water compared to LiPF6, etc. Therefore, LiFSI is used in electrolysis. This facilitates control of the dew point when fabricating the electrode and electrolyte layers. For example, by minimizing moisture content. In addition to dry rooms with inert atmospheres such as argon and controlled dew points, as well as ordinary large It can be handled even in an air-filled environment. Therefore, productivity is improved, which is desirable. Also, LiFSI Furthermore, using a highly dissociative and plasticizing Li salt such as LiTFSA is preferable to using ether. When using lithium conduction that utilizes the segmental motion of the chain, it can be used over a wide temperature range. It is particularly preferable.

[0201] By having little to no organic solvents, secondary batteries can be made less likely to ignite or burn. This allows for improved safety, which is desirable.

[0202] [Exterior] The outer casing of a secondary battery can be made of, for example, metal materials such as aluminum and resin materials. A film-like outer covering can be used. For example, polyethylene, polypropylene, polycarbonate, ionomer, polya On a film made of materials such as mid, aluminum, stainless steel, copper, nickel, etc., which have excellent flexibility A thin metal film is provided, and a polyamide resin is used as the outer surface of the exterior body on top of the thin metal film. A three-layer film with an insulating synthetic resin film, such as an ester resin, can be used. Furthermore, it is preferable to use a fluororesin film as the film. Mu has high stability against acids, alkalis, organic solvents, etc., and is not associated with side effects from reactions in secondary batteries, etc. By suppressing corrosion and other issues, a superior secondary battery can be realized. Fluororesin film and PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkaldehyde) (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), FE P(perfluoroethylenepropene copolymer: tetrafluoroethylene and hexafluoroethylene) Polypropylene copolymer, ETFE (ethylene tetrafluoroethylene copolymer: tetrafluoroethylene copolymer) Examples include copolymers of trafluoroethylene and ethylene.

[0203] This embodiment can be used in appropriate combination with other embodiments.

[0204] (Embodiment 2) This embodiment describes a positive electrode and positive electrode active material composite according to one aspect of the present invention.

[0205] An example of a positive electrode 570b according to one aspect of the present invention is shown in Figure 9. The positive electrode 570b is a positive electrode current collector 571 It has b and a positive electrode active material layer 572b. The positive electrode active material layer 572b is a positive electrode active material composite 100 It has z. For example, the positive electrode active material composite 100z is shown in Figures 10A1 and 10A2. A first active material 100x and a second active material capable of intercepting and releasing carrier ions. It has an active material 100y. In Figure 9, graphene compound 102 and carbide are used as conductive materials. An example using Bombrak 103 is shown, but the positive electrode active material composite 100z has sufficient electrons. If conductivity is present, it is not necessary to use a conductive material in the positive electrode active material layer 572b. The types of materials are not limited to the examples shown in Figure 9, but also include graphene compounds, carbon black, Alternatively, only carbon fibers such as carbon nanotubes may be used, or carbon nanotubes Carbon fibers such as BL and carbon black may be used together. Note that as shown in Figure 9... Although not present, it is preferable that the positive electrode active material layer 572b has a binder. Polymer materials such as polyvinylidene fluoride, and molecular crystal electrolytic materials such as Li(FSI)(SN)2. Quality can be used.

[0206] Furthermore, the positive electrode active material composite 100z is positioned to allow for the exchange of electrons with the positive electrode current collector 571b. This means that the positive electrode active material composite 100z is electrically in contact with the positive electrode current collector 571b. It has. The positive electrode current collector 571b may be provided with an undercoat layer. In this case The positive electrode active material composite 100z is electrically connected to the positive electrode current collector 571b via the undercoat layer. The configuration is such that the positive electrode active material composite 100z is connected to the positive electrode current collector 571 via a conductive material. The configuration may also involve electrical contact with b.

[0207] The density of the positive electrode active material layer 572b is preferably 3.0 g / cm³. 3 The above is more preferable. 3.5g / cm³ 3 More preferably 3.8 g / cm³ 3 The above is preferable. Therefore, to increase the density of the positive electrode active material layer 572b, a pressing process may be performed. However, when pressing is performed, the first active material 100x and positive electrode active material composite described later are used. It is desirable to set the press processing conditions appropriately so as not to damage the 100z structure. .

[0208] [Cathode active material composite] Figures 10A1 to 10C2 are schematic cross-sectional diagrams illustrating the positive electrode active material composite 100z. That is the case.

[0209] Figures 10A1 and 10A2 show the first active material 100x which functions as the positive electrode active material, and the second A positive electrode active material composite having a second active material 100y covering at least a portion of the first active material 100x This is a diagram illustrating the combined 100z. Note that in Figure 10A1, one first active material 100x Although a configuration in which is covered by a second active material 100y has been shown, the present invention is not limited thereto. Alternatively, the configuration may be such that multiple first active materials 100x are covered by a second active material 100y. .

[0210] For example, as shown in Figure 10A2, the first active material 100xa and the first active material 100 The configuration may be such that at least a portion of xb is covered by the second active material 100y. (See Figure 10A2) When the first active material 100xa and the first active material 100xb are in contact with at least a portion of each other. This shows that the first active material 100xa and the first active material 100xb are not in direct contact. This may also be the case. The particle surface of the particulate first active material 100x that functions as the positive electrode active material. In a state in which the second active material 100y covers at least a portion of the surface, preferably substantially the entire surface. As a result, the area in direct contact between the first active material 100x and the electrolyte 576 decreases, and the high-voltage charging state is reduced. Therefore, the elimination of transition metal elements and / or oxygen from the first active material 100x can be suppressed. Therefore, it is possible to suppress capacity degradation due to repeated charging and discharging. Also, high temperature and high voltage charging conditions Furthermore, by being covered with an electrochemically stable second active material 100y, one aspect of the present invention Secondary batteries using the 100z positive electrode active material composite exhibit improved stability at high temperatures and enhanced fire resistance. This makes it possible to achieve effects such as improvement.

[0211] Figures 10B1 and 10B2 show the first active material 100x which functions as the positive electrode active material, and the second A positive electrode active material composite 10 having glass 101 covering at least a portion of the active material 100x This is a diagram illustrating 0z. Note that in Figure 10B1, one first active material 100x is glass. Although a configuration covered by 101 has been shown, the present invention is not limited thereto, and may include a plurality of first The active material 100x may be covered by the glass 101.

[0212] For example, as shown in Figure 10B2, the first active material 100xa and the first active material 100 The glass 101 may cover at least a portion of xb. In Figure 10B2, the first The active material 100xa and the first active material 100xb are shown in the case where at least a portion of them are in contact. However, in the case where the first active material 100xa and the first active material 100xb are not in direct contact, It is also acceptable. The particulate first active material 100x that functions as the positive electrode active material has a small amount of particle surface In a state where glass 101 covers at least a part, preferably the entire area, the first living organism The area in direct contact between the quality 100x and the electrolyte 576 decreases, and in a high-voltage charging state, the first active material Because the desorption of transition metal elements and / or oxygen from 100x can be suppressed, the charge-discharge cycle This suppresses capacity degradation due to recharging. Furthermore, electrochemical charging is possible even under high temperature and high voltage conditions. By being covered with a highly stable glass 101, the positive electrode active material composite 100z according to one aspect of the present invention Secondary batteries using this technology offer advantages such as improved stability at high temperatures and enhanced fire resistance. This becomes possible.

[0213] Figures 10C1 and 10C2 show the first active material 100x which functions as the positive electrode active material, The glass 101 covers at least a portion of the first active material 100x This diagram illustrates a positive electrode active material composite 100z having a second active material 100y in contact with x. Yes. In Figure 10C1, one first active material 100x is covered by glass 101. Although this has been demonstrated, the present invention is not limited thereto, and a plurality of first active materials 100x The configuration may also involve covering the glass 101.

[0214] For example, as shown in Figure 10C2, the first active material 100xa and the first active material 100 The glass 101 may cover at least a portion of xb. In Figure 10C2, the first The active material 100xa and the first active material 100xb are shown in the case where at least a portion of them are in contact. However, in the case where the first active material 100xa and the first active material 100xb are not in direct contact, It is also acceptable. The particulate first active material 100x that functions as the positive electrode active material has a small amount of particle surface In a state in which glass 101 covers at least a part, preferably the entire area, A positive electrode active material composite having a second active material 100y in contact with a first active material 100x via a junction. At 100z, the region in direct contact between the first active material 100x and the electrolyte 576 decreases. Under high-voltage charging conditions, transition metal elements and / or oxygen are desorbed from the first active material 100x. Because it can suppress and, it can suppress capacity degradation due to repeated charging and discharging. Also, high temperature and high Glass 101 is electrochemically stable even under voltage conditions, and also remains stable even under high charging voltage conditions. By being covered with a certain second active material 100y, the positive electrode active material composite 100 according to one aspect of the present invention Secondary batteries using z offer advantages such as improved stability at high temperatures and enhanced fire resistance. This becomes possible.

[0215] In the positive electrode active material composite 100z shown in Figures 10A1 to 10C2, the first active material As 100x, lithium cobalt oxide containing magnesium and fluorine, magnesium, Lithium cobalt oxide containing fluorine, aluminum, and nickel, as well as nickel: Cobalt:Manganese = 8:1:1, and Nickel:Cobalt:Manganese = 9:0.5 High-voltage charging state of nickel-cobalt-manganate lithium with a molar ratio of 0.5, etc. By using a material with excellent stability at high voltage, the above-mentioned positive electrode active material composite 100z can be used at high voltage. The durability and stability during charging can be further improved. Also, the above-mentioned positive electrode active material The heat resistance and / or fire resistance of secondary batteries using the 100z composite can be further improved. Cut.

[0216] Furthermore, lithium cobaltate containing magnesium, fluorine, aluminum, and nickel. Mu has a large amount of magnesium, fluorine, or aluminum in the surface layer of the positive electrode active material, and particles It features a broad distribution of nickel throughout, resulting in remarkably superior charge-discharge cycle characteristics at high voltages. Therefore, it is a particularly preferred material as the first active material 100x. If it contains a large amount of magnesium, fluorine, or aluminum, for example, STEM-ED In X-ray analysis, characteristic X-rays originating from magnesium, fluorine, or aluminum The number of tums has a maximum value at the surface layer. Here, the surface layer refers to the positive electrode active material. This refers to the region from the surface of the material down to about 10 nm. Note that cracks in the positive electrode active material are also included in this region. Having a layer, the additive of magnesium, fluorine, or aluminum in the preparation of the positive electrode active material. Cracks that formed before the processing stage contain a large amount of magnesium, fluorine, or aluminum. It has a surface layer.

[0217] The positive electrode active material composite 100z shown in Figures 10A1 and 10A2 is composed of the first active material 1 A composite treatment using at least 00x and a second active material 100y is obtained. Examples of composite processing include mechanochemical methods, mechanofusion methods, and ball Compounding treatments using mechanical energy such as the Mill process, coprecipitation, hydrothermal methods, and sol-gel methods. Which liquid-phase reaction composite treatment, as well as barrel sputtering, ALD (Atomic Layer Deposition (Layer Deposition) method, vapor deposition method, and CVD (Chemical Vapor Deposition) method. One or more of the following: compounding treatment by gas-phase reaction such as the por Deposition method. A composite treatment can be used. In addition, in the composite treatment, one or more heating It is preferable to perform the treatment. In this specification, composite treatment refers to surface coating. This is sometimes called processing or coating.

[0218] Furthermore, the positive electrode active material composite 100z shown in Figures 10B1 and 10B2 is the first active It is obtained by a composite treatment using at least material 100x and glass 101. Examples of composite processing methods include mechanochemical methods, mechanofusion methods, and ball milling. Compounding treatments using mechanical energy such as the sol-gel method, coprecipitation, hydrothermal method, and sol-gel method. Compounding treatment by liquid-phase reaction, as well as barrel sputtering, ALD method, vapor deposition method, and C One or more of the following composite treatments can be used: composite treatment by gas-phase reaction such as the VD method. Yes, it is possible. Furthermore, in the compounding process, it is preferable to perform one or more heat treatments.

[0219] Furthermore, the positive electrode active material composite 100z shown in Figures 10C1 and 10C2 is at least Composite treatment using the first active material 100x, the second active material 100y, and glass 101. It is obtained by the following methods. Examples of compounding processes include mechanochemical methods and mechanofusion. Compound treatment using mechanical energy such as the ball mill method, coprecipitation method, hydrothermal method, and Compounding processes using liquid-phase reactions such as the bisol-gel method, as well as barrel sputtering and ALD One or more composite treatments by gas-phase reaction such as vapor deposition and CVD. The process can be used. In addition, in the compounding process, one or more heat treatments can be performed. It is preferable to do so.

[0220] As described above, a positive electrode active material composite 100z in one aspect of the present invention comprises a first active material 100x and By not coming into contact with electrolyte 576, the degradation of the first active material 100x due to the electrolyte is prevented. It is suppressed. Such deterioration may be caused by defects occurring in the first active material 100x, for example. For example, one type of defect is called a pit. A pit occurs during charge-discharge cycle testing. This refers to regions where several layers of the main components of the first active material 100x, such as cobalt and oxygen, have been removed. For example, cobalt is thought to leach into the electrolyte. The pit is a charge-discharge cycle. During testing, the pit may progress in the direction of the active material. The shape is not circular but has depth and a groove-like shape. Electrolyte 576 and the first active material. By configuring the 100x and the other parts not to come into contact, the above-mentioned defects, particularly the occurrence and progression of pits, can be suppressed. It is possible.

[0221] The positive electrode active material composite 100z is in contact with the first active material 100x via the glass 101. When there are two active materials 100y, the positive electrode active material composite 100z has a double structure in its surface layer. It can be said that it has a structure. However, the positive electrode active material composite 100z in one aspect of the present invention is glass 1 The present invention is not limited to cases where the 01 and second active materials 100y are arranged in a double structure. Another example of a positive electrode active material composite 100z in one embodiment is a glass 101 and a second active material 10 A glass active material mixed layer having 0y covers at least a portion of the surface of the first active material 100x. It may be a structure like that.

[0222] Furthermore, as a positive electrode active material composite 100z according to one aspect of the present invention, positive electrode active material composite 100z The surface layer or glass active material mixed layer may contain graphene compound 102. Here, Instead of graphene compound 102, carbon black or carbon nanotubes, etc. Raw fibers may also be used.

[0223] As glass 101, a material having an amorphous portion can be used. Examples of materials include SiO2, SiO, Al2O3, TiO2, Li4SiO4, Li 3PO4, Li2S, SiS2, B2S3, GeS4, AgI, Ag2O, Li2O, P A material having one or more selected from 2O5, B2O3, and V2O5, etc., Li7P3S 11 , or Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2、0<y<3 Materials such as , ) can be used. Materials having amorphous parts are used in an amorphous state. This refers to the state in which crystallized glass (also called glass ceramics) is partially crystallized. It is possible to be there. It is desirable that glass 101 has lithium ion conductivity. Lithium ion conductivity refers to the property of having lithium ion diffusion and lithium ion penetration properties. It can also be said that the glass 101 preferably has a melting point of 800°C or lower, and 500°C. It is more preferable that the following conditions are met. It is also preferable that the glass 101 has electronic conductivity. Furthermore, the glass 101 preferably has a softening point of 800°C or lower, for example, Li2 O-B2O3-SiO2 glass can be used.

[0224] It is desirable that the glass 101 has electronic conductivity, but the electronic conductivity of the glass 101 is low. In that case, along with glass 101, graphene compound, carbon black, or carbon By mixing carbon fiber conductive materials such as nanotubes into glass 101, the glass 101 It can impart electronic conductivity.

[0225] Furthermore, at least a portion of the surface of the positive electrode active material composite 100z is covered with a graphene compound. It may have a structure. Preferably, the particle surface of the positive electrode active material composite 100z and / or the positive electrode. A structure in which more than 80% of the aggregate having the active material complex 100z is covered with a graphene compound is preferred. It seems so. Graphene compounds will be discussed later.

[0226] Furthermore, the positive electrode active material composite 100z is preferably covered with a molecular crystalline electrolyte. The molecular crystalline electrolyte can function as a binder for the positive electrode active material layer 572b. Molecular crystalline electrolytes are often materials with high ionic conductivity, and are covered with molecular crystalline electrolytes. The positive electrode active material composite 100z is capable of exchanging carrier ions with the electrolyte 576.

[0227] [Cathode active material] As the first active material 100x, LiM1O2(M1 is a layered rock salt type crystal structure) is used. A composite oxide represented by one or more elements selected from Fe, Ni, Co, and Mn can be used. It can be done. Also, as the first active material 100x, the composite oxide represented by LiM1O2 is added. A material with element X added can be used. The added element X is present in the first active material 100x. Examples include nickel, cobalt, magnesium, calcium, chlorine, fluorine, and aluminum. M, manganese, titanium, zirconium, yttrium, vanadium, iron, chromium, niobium , selected from lanthanum, hafnium, zinc, silicon, sulfur, phosphorus, boron, and arsenic It is preferable to use the above. These elements have the crystal structure of the first active material 100x. This may further stabilize it. In other words, the first active material 100x is magnesium and fluorine It contains lithium cobalt oxide, magnesium, fluorine, aluminum, and nickel. Lithium cobalt oxide having magnesium, fluorine and titanium, Lithium nickel-cobalt oxide containing magnesium and fluorine, magnesium and fluorine Lithium cobalt-aluminate and nickel-cobalt-aluminate containing the element Lithium nickel-cobalt-aluminate containing thium, magnesium, and fluorine , containing magnesium and fluorine, such as lithium nickel-cobalt-manganate. This is possible. Furthermore, the transition metal ratio of nickel-cobalt-lithium manganate is as follows: A high nickel ratio is preferred, for example, nickel:cobalt:manganese = 8:1:1, nickel A material with a molar ratio of Kel:Cobalt:Manganese = 9:0.5:0.5 is preferred. Also, As described above, nickel-cobalt-manganate lithium contains calcium. It is preferable that the material contains lithium balto-manganate.

[0228] Furthermore, as the first active material 100x, LiM1O2 (where M1 is Fe, Ni, Co, Mn A composite oxide secondary particle, represented by one or more selected from the above, is coated with a metal oxide. It may be used. As metal oxides, Al, Ti, Nb, Zr, La, and Li may be selected. One or more metal oxides can be used. For example, LiM1O2(M1 is Fe Secondary particles of a composite oxide (one or more selected from Ni, Co, and Mn) are aluminum oxide. A metal oxide-coated composite oxide coated with nium is used as the first active material 100x. It is possible. For example, nickel:cobalt:manganese = 8:1:1, nickel:cobal Nickel-cobalt-lithium manganese phosphate with a molar ratio of 9:0.5:0.5 The secondary particles of the material are coated with aluminum oxide, and a metal oxide-coated composite oxide is used. This can be done. Here, the coating layer is preferably thin, for example, 1 nm to 200 nm. More preferably, it is 1 nm to 100 nm. Also, the above nickel-cobalt-ma Lithium nickel-cobalt-manganate, which contains calcium, is used as lithium manganate. It is preferable that it has

[0229] As the first active material 100x, the positive electrode active material 100 described in the embodiment below is used. It is possible.

[0230] As the second active material 100y, one or more of oxides and LiM2P having an olivine-type crystal structure O4 (M2 is one or more selected from Fe, Ni, Co, Mn) can be used. Examples of the oxide include aluminum oxide, zirconium oxide, hafnium oxide, and niobium oxide. Examples of LiM2PO4 include LiFePO4, LiNiP O4, LiCoPO4, LiMnPO4, LiFe O4, LiFe a Ni b PO4, LiFe a Co b P O4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4 (a +b is 1 or less, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is 1 or less, 0 < c < 1 , 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. Further, the particle surface of the second active material 100y may have a carbon coating layer.

[0231] Examples of the conductive material include carbon blacks such as acetylene black and furnace black, graphite such as artificial graphite and natural graphite, carbon nanofibers, and so on. Carbon fibers such as carbon nanotubes, and graphene compounds, or one of these or Two or more types can be used.

[0232] This embodiment can be used in appropriate combination with other embodiments.

[0233] (Embodiment 3) In this embodiment, a positive electrode active material according to one aspect of the present invention will be described using Figures 11 to 17. I will reveal it.

[0234] Furthermore, in this specification, crystal planes and directions are indicated by Miller indices. In crystallography, numbers are represented with a superscript bar, but in this specification, due to limitations on patent application notation, the numbers are represented as follows: Sometimes, instead of placing a bar above a letter, a minus sign (-) is placed before the number to represent it. Furthermore, the individual orientations indicating directions within a crystal are [ ], and the collective orientation showing all equivalent directions is < > represents individual crystal planes ( ), and sets of planes with equivalent symmetry are {}. They are expressed accordingly. Also, the Miller indices for trigonal and hexagonal crystals, including R-3m, are (h (hkil) is sometimes used in addition to (kl). Here, i is -(h+k).

[0235] Furthermore, in this specification, etc., layered rock salt type having a composite oxide containing lithium and a transition metal The crystal structure has a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and transitions Because the metal and lithium are arranged in a regular pattern to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. This refers to a crystal structure that is functional. It may contain defects such as vacancies in cations or anions. Furthermore, strictly speaking, the layered rock salt crystal structure is a structure in which the lattice of the rock salt crystal is distorted. There are cases where this occurs.

[0236] Furthermore, in this specification and elsewhere, a rock salt-type crystal structure is defined as a structure in which cations and anions are arranged alternately. This refers to a structure that is formed in this way. Note that even if there is a vacancy of a cation or anion in part of the crystal structure, good.

[0237] Furthermore, in this specification, the theoretical capacity of the positive electrode active material refers to the insertion and removal capacity of the positive electrode active material. This refers to the amount of electricity that would be generated if all possible lithium were to be desorbed. For example, the theoretical capacity of LiFePO4. The theoretical capacity of LiCoO2 is 170mAh / g, while the theoretical capacity of LiNiO2 is 274mAh / g. The capacity is 275 mAh / g, while the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0238] Furthermore, the extent to which insertable and detachable lithium remains in the positive electrode active material is determined by x in the composition formula. For example, Li x x in CoO2, or Li x Indicated by x in MO2. Li in this specification. x CoO2 contains Li as appropriate. x This can be interpreted as MO2.x can be said to represent the occupancy rate. In the case of the positive electrode active material in a secondary battery, x can also be expressed as x = (theoretical capacity - charging capacity) / theoretical capacity. For example, a secondary battery using LiCoO2 as the positive electrode active material was charged to 219.2 mAh / g. In the case of Sen 0.2 It can be expressed as CoO2 or x=0.2. x x during CoO2 Small means, for example, 0.1 <x≦0.24をいう。

[0239] When lithium cobalt oxide approximately satisfies the stoichiometric ratio, it is LiCoO2 and lithium The Li occupancy rate of the light is x=1. Also, a secondary battery that has finished discharging is LiCoO2. Therefore, we can say that x=1. In this context, "discharge has ended" means, for example, when the current is 100mA / g. This refers to a state where the voltage (counter electrode lithium) falls below 2.5V. In the pond, the lithium occupancy rate of the lithium site becomes x=1, and no more lithium can be added. When this happens, the voltage drops sharply. At this point, it can be said that the discharge has ended. Generally, LiC In lithium-ion secondary batteries using oO2, the discharge voltage reaches 2.5V. Since the voltage drops rapidly, we assume that the discharge has ended under the above conditions.

[0240] Furthermore, in this specification, etc., all lithium that can be inserted into and removed from the positive electrode active material is inserted. The charging depth at this time is 0, and when all the insertable and detachable lithium in the positive electrode active material has been detached. The charging depth is sometimes referred to as 1.

[0241] [Cathode active material] A positive electrode active material according to one aspect of the present invention will be described with reference to Figures 11 to 15.

[0242] Figure 11A is a schematic top view of a positive electrode active material 100, which is one embodiment of the present invention. A schematic cross-sectional view of AB is shown in Figure 11B.

[0243] <Elemental composition and distribution> The positive electrode active material 100 comprises lithium, a transition metal, oxygen, and an additive element X. The most active material 100 is LiM1O2 (where M1 is one or more elements selected from Fe, Ni, Co, and Mn). It can also be described as a composite oxide represented by [formula] to which element X has been added.

[0244] The transition metal present in the positive electrode active material 100 belongs to the space group R-3m along with lithium. It is preferable to use a metal that can form layered rock salt-type composite oxides. For example, manganese, co At least one of balt and nickel can be used. In other words, the positive electrode active material 100 is The transition metal may consist solely of cobalt, or solely of nickel. You may use two types of minerals, cobalt and manganese, or two types of minerals, cobalt and nickel, or cobalt Three types may be used: cobalt acid, manganese, and nickel. In other words, the positive electrode active material 100 is cobalt acid Lithium, lithium nickelate, and lithium cobaltate in which part of the cobalt is replaced with manganese. Lithium, lithium cobaltate (where some of the cobalt is replaced with nickel), nickel-manganese -It can have a composite oxide containing lithium and a transition metal, such as lithium cobalt oxide. When nickel is included in addition to cobalt as a transition metal, the bonds are formed in the charged state at high voltage. The crystal structure may become more stable, which is preferable.

[0245] The additive element X in the positive electrode active material 100 is nickel, cobalt, magnesium, Calcium, chlorine, fluorine, aluminum, manganese, titanium, zirconium, yttrium Um, vanadium, iron, chromium, niobium, lanthanum, hafnium, zinc, silicon, sulfur, It is preferable to use one or more elements selected from phosphorus, boron, and arsenic. This may further stabilize the crystal structure of the positive electrode active material 100. In other words, the positive electrode active material 100 Lithium cobalt oxide containing magnesium and fluorine, magnesium, fluorine and titanium Lithium cobaltate containing fluorine, magnesium, and nickel-cobaltate containing fluorine Lithium cobalt-aluminate containing lithium, magnesium, and fluorine, nickel Lithium cobalt-aluminate, magnesium, and fluorine-containing nickel-cobalt Lithium baltoaluminate, magnesium, and fluorine-containing nickel-manganese -It may contain lithium cobalt oxide, etc. In this specification, etc., the additive element X You may replace it with terms like "mixture" or "part of the raw materials" when referring to it.

[0246] As shown in Figure 11B, the positive electrode active material 100 has a surface layer 100a and an interior 100b. It is preferable that the surface layer 100a has a higher concentration of added element X than the interior layer 100b. As shown by the gradient in Figure 11B, the concentration of additive element X increases from the interior to the surface. It is preferable to have a concentration gradient. In this specification, the surface layer 100a refers to the positive electrode active material. This refers to the area from the surface down to about 10 nm. The surface can also be called a surface, and as shown in Figure 11C, the region extends from that surface to about 10 nm. This is called the surface layer 100c. Also, the surface layer 100a and surface layer 100c of the positive electrode active material 100 The deeper region is designated as interior 100b. The positive electrode active material 100 forms the positive electrode active material composite 100z. In such cases, it is desirable that the surface affected by the crack is also covered with glass 101.

[0247] In one embodiment of the present invention, lithium is released from the positive electrode active material 100 upon charging. The concentration of additive element X is such that even if it is removed, the layered structure consisting of octahedrons of cobalt and oxygen will not be destroyed. The high surface layer 100a, that is, the outer periphery of the particle, is reinforced.

[0248] Furthermore, the concentration gradient of the added element X is uniformly distributed throughout the entire surface layer 100a of the positive electrode active material 100. It is preferable that even if a part of the surface layer 100a is reinforced, if there is a part without reinforcement This is because stress may concentrate in areas where there is no stress, which is undesirable. When pressure is concentrated, defects such as cracks can develop, leading to cracking of the positive electrode active material and a decrease in charge / discharge capacity. This could lead to...

[0249] Magnesium is divalent, and lithium is more abundant than the transition metal sites in the layered rock salt crystal structure. Because it is more stable in the umsite, it easily enters the lithiumsite. The presence of lithium at an appropriate concentration in the lithium site of the surface layer 100a results in a layered rock salt type crystal structure. It can be made easier to maintain the structure. Also, because magnesium has a strong bonding force with oxygen, It can suppress the release of oxygen from the surrounding area. Magnesium, if at an appropriate concentration, It is preferable as it does not adversely affect the insertion and removal of lithium associated with electricity. However, if it is excessive This could negatively affect the insertion and removal of lithium.

[0250] Aluminum is trivalent and can be found at transition metal sites in layered rock salt crystal structures. Aluminum can suppress the leaching of cobalt from the surroundings. Also, aluminum Due to its strong binding affinity to oxygen, it can suppress the release of oxygen from around aluminum. Therefore, if aluminum is used as the additive element X, the crystal structure will not break down even after repeated charging and discharging. This allows for the creation of a less prone positive electrode active material 100.

[0251] Fluorine is a monovalent anion, and in the surface layer 100a, some of the oxygen is replaced by fluorine. When this is done, the lithium detachment energy becomes smaller. This is because cobalt associated with lithium detachment occurs. The change in the valence of the toion is from trivalent to tetravalent if it does not contain fluorine, and if it does contain fluorine. This is due to the difference in oxidation-reduction potential between divalent and trivalent states. Therefore, the surface layer of the positive electrode active material 100 If some of the oxygen in 100a is replaced by fluorine, then lithium ions near the fluorine... It can be said that the detachment and insertion of the battery occur smoothly. Therefore, when used in a secondary battery, charging and discharging The electrical characteristics, rate characteristics, etc., are improved, which is desirable.

[0252] Titanium oxide is known to be superhydrophilic. Therefore, the surface layer 100a is By using a positive electrode active material 100 containing tan oxide, the wettability to highly polar solvents is improved. There is a possibility that it will become worse. When used as a secondary battery, the positive electrode active material 100 and the highly polar electrolyte This improves interface contact and may suppress the increase in resistance. In contrast, electrolytes are liquid electrolytes.

[0253] As the charging voltage of a secondary battery increases, the voltage at the positive electrode generally increases. In one aspect of the present invention... The positive electrode active material has a stable crystal structure even at high voltages. The stable crystal structure of the material suppresses the decrease in capacity that occurs with repeated charging and discharging. It is possible.

[0254] Furthermore, a short circuit in a secondary battery can cause malfunctions in the charging and / or discharging operations of the secondary battery. This can not only cause contamination but also lead to overheating and fire. To realize safe rechargeable batteries... Therefore, it is preferable that short-circuit current is suppressed even at high charging voltages. In one embodiment, the positive electrode active material 100 suppresses short-circuit current even at high charging voltages. Therefore, it is possible to create a secondary battery that achieves both high capacity and safety.

[0255] A secondary battery using the positive electrode active material 100 according to one aspect of the present invention preferably has high capacity and excellent It satisfies both charge / discharge cycle characteristics and safety requirements simultaneously.

[0256] The concentration gradient of the added element X can be determined, for example, by energy-dispersive X-ray spectroscopy (EDX: Energ It can be evaluated using dispersive X-ray spectroscopy. EDX measurement involves scanning within a region to perform measurements and evaluate the region in two dimensions. This is sometimes called EDX surface analysis. Additionally, data for linear regions can be extracted from EDX surface analysis. Furthermore, evaluating the distribution of atomic concentrations within positive electrode active material particles is sometimes called line analysis. .

[0257] EDX surface analysis (e.g., elemental mapping) was performed to determine the surface layer 100a of the positive electrode active material 100. The concentration of additive element X in the interior 100b and near grain boundaries can be quantitatively analyzed. Yes, it is possible. Furthermore, EDX radiation analysis can be used to analyze the concentration distribution of the added element X.

[0258] When EDX radiation analysis was performed on the positive electrode active material 100, the magnesium concentration of the surface layer 100a was The peak (the position where the concentration is at its maximum) is located from the surface of the positive electrode active material 100 towards the center. It is preferable that they exist up to a depth of 3 nm, and more preferably up to a depth of 1 nm. Furthermore, it is even more preferable that they exist up to a depth of 0.5 nm.

[0259] Furthermore, the distribution of fluorine in the positive electrode active material 100 can be superimposed on the distribution of magnesium. This is preferable. Therefore, when EDX radiation analysis is performed, the peak of fluorine concentration in the surface layer 100a (concentration) The position where the degree is at its maximum is a depth of 3 nm from the surface of the positive electrode active material 100 toward the center. It is preferable that it be present at a depth of 1 nm, more preferably at a depth of 0.5 It is even more preferable that they be present up to nm.

[0260] Note that not all additive elements X have the same concentration distribution. For example, the positive electrode active material 100 When aluminum is used as additive element X, the distribution is slightly different from that of magnesium and fluorine. It is preferable that this is the case. For example, when EDX radiation analysis is performed, the aluminum in the surface layer 100a The peak of magnesium concentration (the position where the concentration is at its maximum) is lower than the peak of magnesium concentration (the position where the concentration is at its maximum). It is preferable that the position where the degree is at its maximum is close to the surface. For example, the peak of aluminum concentration It exists at a depth of 0.5 nm to 20 nm from the surface of the positive electrode active material 100 toward the center. It is preferable that it exists at a depth of 1 nm to 5 nm, and more preferably that it exists at a depth of 1 nm to 5 nm.

[0261] Furthermore, when linear or surface analysis was performed on the positive electrode active material 100, the addition near the grain boundary was observed. The ratio of element X to transition metal M1 (X / M1) is preferably between 0.020 and 0.50. Furthermore, a value of 0.025 or more and 0.30 or less is preferable. Moreover, a value of 0.030 or more and 0.20 or less is preferable. Preferred. For example, when the additive element X is magnesium and the transition metal M1 is cobalt, The ratio of magnesium to cobalt atoms (Mg / Co) should ideally be between 0.020 and 0.50. It is preferable that it be between 0.025 and 0.30. Furthermore, a value between 0.030 and 0. A value of 20 or less is preferable.

[0262] As mentioned above, if the additive element X in the positive electrode active material 100 is in excess, lithium This may negatively affect insertion and removal. Furthermore, when used as a secondary battery, it may increase resistance and capacity. This may lead to a decrease in quality, etc. On the other hand, if there is a deficiency, it will not be distributed throughout the entire surface layer 100a, and the crystal structure will not be affected. The effect of retaining may become insufficient. Thus, the added element X is added to the positive electrode active material 100. Adjust the concentration to the appropriate level.

[0263] Therefore, for example, the positive electrode active material 100 has regions where the excess additive element X is unevenly distributed. This is also good. The existence of such regions removes excess additive element X from other regions. The concentration of additive element X is appropriate in most of the interior and surface layers of the positive electrode active material 100. This can be achieved. The appropriate concentration of additive element X in most of the interior and surface layer of the positive electrode active material 100. This makes it possible to suppress the increase in resistance and decrease in capacity when used as a secondary battery. The ability to suppress the increase in resistance of secondary batteries is extremely advantageous, especially in high-rate charging and discharging. It is a desirable characteristic.

[0264] Furthermore, in the positive electrode active material 100 having regions where excess additive element X is unevenly distributed, the manufacturing process In production, it is permissible to mix in an excess of additive element X. The wider range of motion is preferable.

[0265] In this specification, etc., uneven distribution means that the concentration of a certain element is distributed between a certain region A and a certain region B. It refers to differences. Examples include segregation, precipitation, heterogeneity, bias, high or low concentration, etc. That's fine.

[0266] <Crystal structure> Materials with a layered rock salt-type crystalline structure, such as lithium cobalt oxide (LiCoO2), emit It is known to have high electrical capacity and is excellent as a positive electrode active material for secondary batteries. Examples of materials having a crystalline structure include LiM1O2 (where M1 is derived from Fe, Ni, Co, and Mn). Examples include composite oxides represented by one or more selected items.

[0267] The Jahn-Teller effect in transition metal compounds depends on the number of electrons in the d orbitals of the transition metal. It is known that the strength of their effects varies.

[0268] In nickel-containing compounds, distortion is likely to occur due to the Jahn-Teller effect. Therefore, when charging and discharging LiNiO2 at high voltage, distortion occurs. There is a concern that this will lead to a breakdown of the crystal structure. In LiCoO2, the Jahn-Teller effect The impact is suggested to be small, and it may be preferable as it may have better resistance to charging and discharging at high voltages. It's nice.

[0269] The structure of the positive electrode active material will be explained using Figures 12 to 17. This section describes the case where cobalt is used as the transition metal in the positive electrode active material.

[0270] <Conventional positive electrode active material> The positive electrode active material shown in Figure 14 is lithium cobalt oxide without the addition of halogen and magnesium. It is lithium (LiCoO2, LCO). The lithium cobalt oxide shown in Figure 14 is charged at depth of charge. Therefore, the crystal structure changes. In other words, when written as LixCoO2, the lith The crystal structure of umcite changes depending on the lithium occupancy rate x.

[0271] As shown in Figure 14, lithium cobalt oxide in the state x=1 (discharge state) is a space group It has a region with an R-3m crystal structure, and there are three CoO2 layers in the unit cell. Therefore, this crystal structure is sometimes called the O3 type crystal structure. Note that the CoO2 layer is a different type of layer. This refers to an octahedral structure in which oxygen atoms are coordinated in six positions, and which is continuous in the planar direction while sharing edges. Let's assume that.

[0272] Furthermore, when x=0, it has a crystal structure of space group P-3m1, and CoO2 is present in the unit cell. A single layer exists. Therefore, this crystal structure is sometimes called an O1 type crystal structure.

[0273] Furthermore, lithium cobalt oxide at x=0.12 has a crystal structure with space group R-3m. This structure is a combination of the CoO2 structure, such as P-3m1(O1), and the R-3m(O3) structure. It can also be described as a structure in which LiCoO2 and other structures are alternately stacked. Therefore, this crystal structure This structure is sometimes called the H1-3 type crystal structure. Note that actual lithium insertion and removal processes are irregular. Because this can occur, experimentally, the H1-3 type crystal structure can be observed from around x=0.25. Actually, the H1-3 type crystal structure has a different number of cobalt atoms per unit cell compared to other structures. It is twice as large. However, in this specification, including Figure 14, it is made easier to compare with other structures. Therefore, the H1-3 type crystal structure will be shown with the c-axis halved to represent half the size of the unit cell.

[0274] As an example, the H1-3 type crystal structure uses the coordinates of cobalt and oxygen in the unit cell, C o(0, 0, 0.42150±0.00016), O1(0, 0, 0.27671±0. It can be expressed as 00045) and O2(0,0,0.11535±0.00045). O1 and O2 are oxygen atoms, respectively. Thus, the H1-3 type crystal structure is one cobalt It is represented by a unit cell using a tubular and two oxygen atoms. On the other hand, as will be described later, this generation One embodiment of the O3' type crystal structure is preferably a y This is represented by a nit cell. This is the case for the O3' type crystal structure and the H1-3 type structure. The symmetry between cobalt and oxygen is different, and the O3' type crystal structure is more complex than the H1-3 type structure. This shows that the change from the O3 structure is small. The crystal structure of the positive electrode active material is small in all of them. The choice of whether it is preferable to represent it using unit cells is, for example, the Lee of the XRD pattern. In Tobert analysis, the GOF (goodness of fit) value becomes smaller. You should choose accordingly.

[0275] High-voltage charging such that the charging voltage is 4.6V or higher based on the oxidation-reduction potential of lithium metal. If you repeatedly charge and discharge to a deep depth where x = 0.24 or less, Lithium baltate has an H1-3 type crystal structure and a structure between the R-3m(O3) state in the discharge state. This results in repeated changes in the crystal structure (i.e., non-equilibrium phase transitions).

[0276] However, these two crystal structures show a large displacement of the CoO2 layer. (See dotted line in Figure 14) And as shown by the double arrows, in the H1-3 type crystal structure, the CoO2 layer is from R-3m(O3) The deviation is significant. Such dynamic structural changes negatively affect the stability of the crystal structure. It can be given.

[0277] Furthermore, the volume difference is also large. When comparing per the same number of cobalt atoms, H1-3 type crystal The difference in volume between the structure and the O3-type crystal structure in the discharged state is 3.0% or more.

[0278] In addition, the H1-3 type crystal structure has a continuous CoO2 layer, such as P-3m1(O1). The resulting structure is likely to be unstable.

[0279] Therefore, repeated high-voltage charging and discharging causes the crystalline structure of lithium cobalt oxide to break down. The breakdown of the crystal structure causes a deterioration in cycle properties. This reduces the number of sites where lithium can exist stably, and also makes lithium insertion and removal more difficult. This is likely the reason.

[0280] <Positive electrode active material according to one aspect of the present invention> <Internal> In one embodiment of the present invention, the positive electrode active material 100 undergoes repeated high-voltage charging and discharging, and CoO2 It can reduce the displacement of layers. Furthermore, it can reduce the change in volume. Therefore, the positive electrode active material according to one embodiment of the present invention can achieve excellent cycle characteristics. Furthermore, the positive electrode active material according to one aspect of the present invention can adopt a stable crystal structure in a high-voltage charged state. Therefore, the positive electrode active material of one aspect of the present invention, when a high-voltage charge state is maintained, In some cases, short circuits are less likely to occur. In such cases, safety is further improved, which is preferable. It seems so.

[0281] In one embodiment of the present invention, the positive electrode active material is in a fully discharged state and a high-voltage charged state. In this case, the difference in volume when comparing the change in crystal structure and the same number of transition metal atoms is small. Sai.

[0282] Figure 12 shows the crystal structure of the positive electrode active material 100 before and after charging and discharging. The positive electrode active material 100 is lithium It is a composite oxide containing um, cobalt as a transition metal, and oxygen. In addition to the above It is preferable to have magnesium as the additive element X. Also, fluorine as the additive element X. It is preferable that the halogen is present, such as chlorine.

[0283] The crystal structure at x=1 (discharge state) in Figure 12 is R-3m(O3), the same as in Figure 14. In contrast, the positive electrode active material 100 of one aspect of the present invention, when fully charged to a charge depth, H1-3 It has crystals with a structure different from the type crystal structure. This structure belongs to the space group R-3m, and the cobalt Ions such as thuuth and magnesium occupy the oxygen 6-coordinate positions. Furthermore, the CoO2 layer in this structure The symmetry is the same as that of the O3 type. Therefore, this structure is referred to as the O3' type crystal structure in this specification. Furthermore, in the diagram of the O3' type crystal structure shown in Figure 12, the symmetry of the cobalt atom and the acid In order to explain the symmetry of elementary atoms, lithium is omitted from the representation, but in reality, Co Between the O2 layers, there is lithium present in a concentration of, for example, less than 20 atoms relative to cobalt.

[0284] In the O3' type crystal structure, light elements such as lithium may occupy the oxygen 4-coordinate position. It may be possible.

[0285] Furthermore, the O3' type crystal structure has lithium randomly between the layers, but the CdCl2 type crystal structure It can also be said that it is a crystal structure similar to the crystal structure. This is a crystal similar to the CdCl2 type. The structure is such that when lithium nickelate is charged to a charging depth of 0.94 (Li 0.06 NiO 2) A layered rock with a crystal structure similar to that of pure lithium cobaltate, or rich in cobalt. It is known that salt-type cathode active materials do not usually adopt this crystal structure.

[0286] In one embodiment of the present invention, the positive electrode active material 100 is charged at a high voltage and a large amount of lithium is released. In this case, the change in crystal structure is suppressed compared to conventional cathode active materials. For example, in Figure 12... As shown by the dotted lines, there is almost no displacement of the CoO2 layer in these crystal structures.

[0287] More specifically, in one embodiment of the present invention, the positive electrode active material 100 is such that when the charging voltage is high It also has high structural stability. For example, conventional cathode active materials have an H1-3 type crystal structure. Even at a charging voltage, for example, a voltage of about 4.6V based on the potential of lithium metal, R-3 There is a charging voltage range in which the crystal structure of m(O3) can be maintained, and further increasing the charging voltage... In the range, for example, at a voltage of about 4.65V to 4.7V with the potential of lithium metal as the reference. There is also a region where it can adopt an O3' type crystal structure. Furthermore, when the charging voltage is increased, H Type 1-3 crystals may be observed. Furthermore, in secondary batteries, for example, as a negative electrode active material... When using graphite, for example, even when the voltage of the secondary battery is between 4.3V and 4.5V, R There is a charging voltage range in which the -3m(O3) crystal structure can be maintained, and further increasing the charging voltage... In the range, for example, between 4.35V and 4.55V with the potential of lithium metal as the reference. There is also a region where it can adopt an O3' type crystal structure.

[0288] Therefore, in the positive electrode active material 100 of one aspect of the present invention, charging and discharging at high voltage is repeated Even if it is damaged, the crystal structure is less likely to collapse.

[0289] Furthermore, the positive electrode active material 100 has an O3-type crystal structure at x=1 and an O3'-type crystal structure at x=0.2. The volume difference per unit cell in the structure is 2.5% or less, more specifically 2.2% or less.

[0290] In the O3' type crystal structure, the coordinates of cobalt and oxygen in the unit cell are Co(0, This can be shown within the range 0,0.5, O(0,0,x), and 0.20≦x≦0.25. .

[0291] Additive element X is randomly and dilutely present between the CoO2 layers, that is, at the lithium sites, for example. Magnesium has the effect of suppressing the shifting of the CoO2 layer. Therefore, The presence of magnesium makes it easier for the O3' type crystal structure to form. Therefore, magnesium is the primary It is distributed in at least a portion of the surface layer of the positive electrode active material 100 in one embodiment of the positive electrode active It is preferable that magnesium is distributed throughout the entire surface layer of substance 100. To distribute the positive electrode active material 100 throughout the entire surface layer of quality 100, a method for preparing positive electrode active material 100 according to one aspect of the present invention is used. In the process, heat treatment is preferable.

[0292] However, if the heat treatment temperature is too high, cation mixing occurs and the added element X For example, magnesium is more likely to enter the cobalt site. The magnesium does not have the effect of maintaining the structure of R-3m under high-voltage charging conditions. If the heat treatment temperature is too high, the cobalt will be reduced to a divalent state, and lithium will... There are concerns about adverse effects such as evaporation.

[0293] Therefore, a heat treatment is performed to distribute magnesium throughout the surface layer of the positive electrode active material 100. Before that, halogen compounds such as fluorine compounds are added to lithium cobalt oxide. Preferred. Adding halogen compounds causes a decrease in the melting point of lithium cobalt oxide. Melting point By lowering the temperature, magnesium can be used as the positive electrode active material at a temperature where cation mixing is less likely to occur. It becomes easy to distribute it throughout the entire surface layer of 100. Furthermore, if a fluorine compound is present... This is expected to improve corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte.

[0294] Furthermore, increasing the magnesium concentration beyond the desired value reduces its effect on stabilizing the crystal structure. In some cases, this can occur. Magnesium, in addition to lithium sites, also contains cobalt sites. This is thought to be because it will also be able to enter the to The number of um atoms is preferably between 0.001 and 0.1 times the number of transition metal atoms such as cobalt. Furthermore, a ratio greater than 0.01 and less than 0.04 is more preferable, and around 0.02 is even better. It seems so. The magnesium concentration shown here is, for example, obtained using ICP-MS for the positive electrode active material. This could be the value obtained from the overall elemental analysis, or the original value obtained during the process of manufacturing the positive electrode active material 100. It may also be based on the values ​​of the ingredient proportions.

[0295] Lithium cobalt oxide can be mixed with a metal other than cobalt (hereinafter referred to as additive element X), such as nickel. One or more metals selected from aluminum, manganese, titanium, vanadium, and chromium. It is also possible to add the following, and it is particularly preferable to add one or more nickel and aluminum. Manganese, titanium, vanadium, and chromium can be stable in their tetravalent state. In some cases, it contributes significantly to structural stability. By adding additive element X, charging at high voltage is possible. In some cases, the crystal structure becomes more stable in the electrostatic state. Here, in one aspect of the present invention, the positive electrode active In the substance, the additive element X is concentrated in a way that does not significantly alter the crystallinity of lithium cobalt oxide. It is preferable to add it in a certain amount. For example, to an amount that does not exhibit the aforementioned Jahn-Teller effect, etc. It is preferable that the amount be [amount].

[0296] Nickel, manganese, and other transition metals, as well as aluminum, are found in cobalt sites. It is preferable to do so, but some may be present at the lithium site. Also, magnesium It is preferable that it be present at the lithium site. Oxygen may be partially substituted with fluorine. good.

[0297] As the magnesium concentration of the positive electrode active material in one aspect of the present invention increases, the volume of the positive electrode active material The amount may decrease. One possible reason for this is the entry of magnesium into the lithium site. This may reduce the amount of lithium that contributes to charging and discharging. One embodiment of the present invention The positive electrode active material has nickel in addition to magnesium as an additive element X. In some cases, the charge-discharge cycle characteristics can be improved. Also, the positive electrode activity in one aspect of the present invention The substance contains aluminum in addition to magnesium as an additive element X, In some cases, the discharge cycle characteristics can be improved. Also, as the additive element X, magnesium By using a positive electrode active material according to one aspect of the present invention, which has um, nickel, and aluminum, In some cases, this can improve the charge-discharge cycle characteristics.

[0298] The present invention, wherein the additive element X is magnesium, nickel, and aluminum, is described below. We will examine the elemental concentrations of a positive electrode active material in one embodiment.

[0299] The number of nickel atoms in the positive electrode active material according to one aspect of the present invention is 10% of the number of cobalt atoms. The following are preferred, more preferably 7.5% or less, and even more preferably 0.05% to 4%. A nickel concentration of 0.1% to 2% is particularly preferred. The nickel concentration shown here is, for example, ICP -This may be a value obtained by performing an elemental analysis of the entire positive electrode active material using MS, etc. This may be based on the values ​​of the raw material proportions during the manufacturing process.

[0300] If a high-voltage charge is maintained for a long period of time, the constituent elements of the positive electrode active material will dissolve into the electrolyte. There is a risk that the crystal structure will collapse. However, by having nickel in the above proportion, the positive electrode active material In some cases, it may be possible to suppress the leaching of constituent elements from quality 100.

[0301] The number of aluminum atoms in the positive electrode active material according to one aspect of the present invention is equal to the number of cobalt atoms. A is preferably between 0.05% and 4%, and more preferably between 0.1% and 2%. Hereinafter, A The luminium concentration can be determined, for example, by performing an elemental analysis of the entire cathode active material using ICP-MS. It may be a value obtained by hand, or it may be based on the values ​​of the raw material composition during the process of manufacturing the positive electrode active material. stomach.

[0302] Furthermore, a positive electrode active material having an additive element X according to one aspect of the present invention uses phosphorus as the additive element X. It is preferable that it contains a compound containing phosphorus and oxygen. It is preferable to have it.

[0303] In one embodiment of the present invention, the positive electrode active material has a compound containing phosphorus as an additive element X. When a high temperature and high voltage charging state is maintained for a long period of time, a short circuit is less likely to occur. There is.

[0304] In one embodiment of the present invention, when the positive electrode active material contains phosphorus as the additive element X, the electrolyte decomposes. The hydrogen fluoride generated by this process reacts with phosphorus, potentially lowering the concentration of hydrogen fluoride in the electrolyte. There is.

[0305] If the electrolyte contains LiPF6 as a lithium salt, hydrolysis will generate hydrogen fluoride. This can occur. Also, there is a reaction between PVDF, which is used as a component of the positive electrode, and alkali. Hydrogen fluoride may be generated as a result. This may suppress corrosion of the current collector and / or peeling of the coating. Also, PVDF This may help suppress the decrease in adhesiveness due to gelation and / or insolubilization.

[0306] One embodiment of the present invention has a positive electrode active material 100 having phosphorus and magnesium as additive elements X. In this case, the stability in a high-voltage charging state is extremely high. The additive element X is phosphorus and magnesium. When sodium is present, the number of phosphorus atoms is preferably between 1% and 20% of the number of cobalt atoms. More preferably 2% to 10%, even more preferably 3% to 8%, and in addition, The number of magnesium atoms is preferably 0.1% to 10% of the number of cobalt atoms, and 0.5 A concentration of % or more and 5% or less is more preferable, and a concentration of 0.7% or more and 4% or less is even more preferable. The phosphorus shown here The magnesium concentration is determined, for example, using ICP-MS to determine the overall concentration of the positive electrode active material 100. The values ​​may be those obtained from elementary analysis, or the raw material composition during the process of manufacturing the positive electrode active material 100. It may also be based on the value.

[0307] If the positive electrode active material 100 has a crack, phosphorus, more specifically, for example, is present inside it. The presence of compounds containing oxygen can sometimes inhibit the progression of cracks.

[0308] Note that in Figure 12, the symmetry of the oxygen atom differs slightly between the O3-type crystal structure and the O3'-type crystal structure. They are quite different. Specifically, in the O3 type crystal structure, oxygen atoms are aligned along the dotted lines, whereas Therefore, the oxygen atoms in the O3' type crystal structure are not strictly aligned. This is because in the O3' type crystal structure... As lithium decreases, tetravalent cobalt increases, and the Jahn-Teller strain becomes larger. This is due to the distortion of the octahedral structure of O6. Also, as lithium decreases, the oxygen in the CoO2 layer... The increased resistance from the samurai class also played a role.

[0309] <Surface layer 100a> Magnesium is distributed throughout the entire surface layer of the positive electrode active material 100 according to one embodiment of the present invention. Preferably, the magnesium concentration in the surface layer 100a is higher than the overall average. This is preferable. For example, the magnesium concentration of the surface layer 100a measured by XPS, etc. It is preferable that the magnesium concentration is higher than the overall average magnesium concentration measured by ICP-MS or the like.

[0310] Furthermore, the positive electrode active material 100 in one aspect of the present invention may contain elements other than cobalt, such as nickel, etc. In the case where there is one or more metals selected from luminium, manganese, iron, and chromium, It is preferable that the concentration of the metal near the particle surface is higher than the overall average. For example, The concentrations of elements other than cobalt in the surface layer 100a, as measured by XPS, etc., are measured by ICP-MS, etc. It is preferable that the concentration of the element is higher than the overall average concentration measured.

[0311] The surface of the positive electrode active material 100 is, so to speak, entirely composed of crystal defects, and during charging, the surface... Because lithium leaks out, this area tends to have a lower lithium concentration than the interior. Therefore, it is prone to instability and its crystal structure is easily disrupted. The magnesium concentration in the surface layer 100a is If the level is high, changes in the crystal structure can be suppressed more effectively. Also, the surface layer 100a A higher magnesium concentration improves corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte. It can also be expected.

[0312] Furthermore, halogens such as fluorine are also present in the surface layer 100a of the positive electrode active material 100 according to one aspect of the present invention. It is preferable that the concentration is higher than the overall average. Surface layer 1, which is the region in contact with the electrolyte. The presence of halogen in 00a effectively improves corrosion resistance to hydrofluoric acid. can.

[0313] Thus, the surface layer 100a of the positive electrode active material 100 in one aspect of the present invention is larger than the interior 100b. The composition is different from the interior, with high concentrations of additive elements, such as magnesium and fluorine. It is preferable that the composition adopts a crystalline structure that is stable at room temperature. The surface layer 100a may have a different crystal structure from the interior 100b. For example, the present invention In one embodiment, at least a portion of the surface layer 100a of the positive electrode active material 100 has a rock salt-type crystalline structure. It may have. Also, if the surface layer 100a and the interior 100b have different crystal structures, It is preferable that the crystal orientations of the surface layer 100a and the interior 100b are roughly the same.

[0314] Layered rock salt crystals, and the anions of rock salt crystals, have a cubic close-packed structure (face-centered cubic lattice structure). ) takes this form. It is also presumed that in O3' type crystals, the anions take on a cubic close-packed structure. In the specification, layers A, B, and C, which have anions, are arranged such that ABCABC are relative to each other. If the structure is one in which particles are stacked in a shifted manner, it will be called a cubic close-packed structure. Therefore, anions It does not have to be a strictly cubic lattice. At the same time, real crystals always have defects, so the analysis results However, this does not necessarily have to be exactly as predicted by theory. For example, FFT (fast processing) of electron diffraction or TEM images. In the Fourier transform, the spot may appear at a position slightly different from its theoretical position. For example, if the orientation from the theoretical position is 5 degrees or less, or 2.5 degrees or less, then it is a cubic close-packed structure. It can be said that this is the case.

[0315] When layered rock salt crystals and rock salt crystals come into contact, a cubic close-packed structure composed of anions is formed. There are crystal planes where the orientation of the formation is aligned.

[0316] Alternatively, it can be explained as follows: In the (111) plane of the cubic crystal structure The anions have a triangular arrangement. The layered rock salt type has a space group R-3m and is rhombohedron Regarding its structure, it is generally represented by a composite hexagonal lattice to facilitate understanding of the structure, and is of the layered salt rock type. The (0001) face has a hexagonal lattice. The triangular lattice of the cubic (111) is of the layered rock salt type. It has an atomic arrangement similar to the hexagonal lattice of the 0001) plane. The consistency between the two lattices is confirmed by It can be said that the orientation of the cubic close-packed structure is aligned.

[0317] However, the space group of layered rock salt crystals and O3'-type crystals is R-3m, and the space group of rock salt crystals is R-3m. The space groups Fm-3m (the space group of typical rock salt crystals) and Fd-3m (the simplest symmetry) Because it is different from the space group of rock salt-type crystals having the above conditions, the Miller indices of crystal planes satisfying the above conditions These differ between layered rock salt crystals and O3'-type crystals, and in rock salt crystals, they are different. In this specification, layered rock In salt-type crystals, O3'-type crystals, and rock salt-type crystals, the cubic ions are composed of anions. When the orientations of the densely packed structures are aligned, it can be said that the crystal orientations are roughly consistent.

[0318] The approximate agreement of the crystal orientation in the two regions can be seen in TEM (transmission electron microscope) images and STE (spherical spectroscopy) images. M (Scanning Transmission Electron Microscope) image, HAADF-STEM (High-angle scattering annular dark-field scanning transmission electron microscope) image. Microscope images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, electron diffraction, TEM This can be determined from FFT and other analyses of images, etc. X-ray diffraction (XRD) and neutron diffraction can also be used for analysis. It can be used as a material.

[0319] Figure 16 shows a TEM image where the orientations of layered rock salt crystals (LRS) and rock salt crystals (RS) are roughly consistent. Examples are shown, such as TEM images, STEM images, HAADF-STEM images, ABF-STEM images, etc. This yields an image that reflects the crystal structure.

[0320] For example, in high-resolution images from TEM, contrast originating from crystal planes can be obtained. Through diffraction and interference of lines, electron beams can be directed perpendicular to the c-axis of, for example, a layered rock salt composite hexagonal lattice. When incident, the contrast originating from the (0003) plane appears as a repetition of bright and dark lines. Therefore, a repetition of bright and dark lines can be observed in the TEM image, and the bright lines (for example) For example, L shown in Figure 16 RS and L LRS If the angle of ) is 5 degrees or less, or 2.5 degrees or less It can be determined that the crystal planes are roughly in agreement, that is, that the crystal orientations are roughly in agreement. Yes, it is possible. Similarly, if the angle between the dark lines is 5 degrees or less, or 2.5 degrees or less, the crystal is also possible. It can be concluded that the orientations are roughly consistent.

[0321] Furthermore, HAADF-STEM images provide contrast corresponding to atomic number, Elements with a larger chromaticity are observed to be brighter. For example, the layered rock salt type koba belonging to space group R-3m In the case of lithium luteoate, cobalt (atomic number 27) has the largest atomic number, so cobal The electron beam is strongly scattered at the position of the cobalt atom, and the arrangement of cobalt atoms becomes a bright line or a point of high brightness. It is observed as an arrangement. Therefore, lithium cobalt oxide, which has a layered rock salt type crystal structure, When observed perpendicular to the c-axis, the arrangement of cobalt atoms perpendicular to the c-axis is bright or shows strong brightness. Observed as a sequence of dots, the arrangement of lithium atoms and oxygen atoms appears as dark lines or low-luminosity regions. It is observed as follows: Fluorine (atomic number 9) and methyl fluoride are added as additive elements to lithium cobaltate. The same applies when it contains magnesium (atomic number 12).

[0322] Therefore, in the HAADF-STEM image, bright and dark lines appear in two regions with different crystal structures. If the repetition of the above is observed, and the angle between bright fringes is 5 degrees or less, or 2.5 degrees or less, then the original The arrangement of the particles is roughly consistent, that is, the orientation of the crystals is roughly consistent. Yes, it is possible. Similarly, if the angle between the dark lines is 5 degrees or less, or 2.5 degrees or less, the crystal is also possible. It can be concluded that the orientations are roughly consistent.

[0323] In ABF-STEM, elements with smaller atomic numbers appear brighter, but the atomic number... Since it is similar to HAADF-STEM in that it can obtain appropriate contrast, HAAD The orientation of the crystal can be determined in the same way as with F-STEM images.

[0324] Figure 17A shows that the orientation of layered rock salt crystals (LRS) and rock salt crystals (RS) is roughly consistent in STEM. Examples of images are shown. The FFT of the region of rock salt crystal RS is shown in Figure 17B, and the region of layered rock salt crystal LRS is shown. The FFT of the region is shown in Figure 17C. In Figures 17B and 17C, the literature values ​​are shown on the left and the measured values ​​are shown on the right. The spots marked with an O represent zero-order diffraction.

[0325] The spots labeled A in Figure 17B originate from 11-1 reflection in the cubic crystal. Figure 17 The spots marked A in C originate from layered salt rock type 0003 reflection. Here, Figure It can be seen that the line passing through AO in Figure 17B and the line passing through AO in Figure 17C are approximately parallel. That is, from Figures 17B and 17C, the orientation of 11-1 reflection of cubic crystals and layered rock salt It can be seen that the direction of reflection of type 0003 roughly matches. "Approximately parallel" means that the angle is 5 degrees or less, or 2.5 degrees or less.

[0326] Thus, FFT and electron diffraction show that the orientation of layered rock salt crystals and rock salt crystals are roughly in agreement. When this is done, the layered rock salt type has an <0003> orientation or an equivalent surface orientation, and the rock salt type has an <1 1-1) The orientation or the equivalent plane orientation may roughly coincide. In this case, These reciprocal lattice points are preferably spot-like, that is, not continuous with other reciprocal lattice points. It is clear that the reciprocal lattice points are spot-like and not continuous with other reciprocal lattice points, indicating high crystallinity. It means...

[0327] Furthermore, as mentioned above, the 11-1 reflection orientation of cubic crystals and the 0003 reflection orientation of layered rock salt types If these roughly coincide, depending on the direction of incidence of the electron beam, layered rock salt type 0003 reflection may occur. Spots not originating from layered salt-type 0003 reflections can be observed in a reciprocal lattice space that differs from the orientation of layered salt rock. It can be measured. For example, the spot marked B in Figure 17C is a layered rock salt type 10-14 This originates from reflection. This is a reciprocal lattice point (Figure 17) derived from 0003 reflection of layered rock salt type. The angle from direction A of C is between 52° and 56° (i.e., ∠AOB is between 52° and 56°). (The angle is 56° or less above), and d is observed in a region between 0.19 nm and 0.21 nm. There is. Note that this index is just one example and does not necessarily have to match it. For example, It would also be acceptable to use reciprocal lattice points equivalent to 0003 and 1014.

[0328] Similarly, in a reciprocal lattice space different from the orientation in which cubic 11-1 was observed, cubic 11-1 Spots that are not of origin may be observed. For example, the spot labeled B in Figure 17B. This originates from the 200 reflection of the cubic crystal. This is the reflection originating from the 11-1 of the cubic crystal ( From the direction A) in Figure 17B, the angle is between 54° and 56° (i.e., ∠AOB is 5°). Diffraction spots may be observed at locations between 4° and 56°. This is just one example, and it is not necessary to match it exactly. For example, 11-1 and 200 are equivalent. A reciprocal lattice point is also acceptable.

[0329] Furthermore, layered rock salt type cathode active materials, including lithium cobalt oxide, have a (0003) face. And the equivalent plane thereof, as well as the (10-14) plane and its equivalent plane, appear as crystal planes. It is known to be prone to deformation. Therefore, the shape of the positive electrode active material should be carefully observed using an SEM or similar device. Therefore, in order to make the (0003) plane easier to observe, for example, in a TEM, an electron beam is used [1-2 10] It is possible to thin-section the observation sample using FIB or similar methods so that it becomes the incident light. If you want to determine the consistency of the orientation, the (0003) plane of layered rock salt is easy to observe. It is preferable to thin it into flakes.

[0330] However, the surface layer 100a consists only of MgO, or a structure in which MgO and CoO(II) are in solid solution. However, this makes it difficult to insert and remove lithium. Therefore, the surface layer 100a is small. It also contains cobalt, and in the discharge state, it also contains lithium, and has a path for lithium insertion and removal. It is necessary to have this. Furthermore, a higher concentration of cobalt than magnesium is preferable.

[0331] Furthermore, the additive element X is located in the surface layer 100a of the particles of the positive electrode active material 100 according to one embodiment of the present invention. It is preferable to do so. For example, the positive electrode active material 100 of one aspect of the present invention has an additive element X. It may be covered with a coating.

[0332] <Grain boundary> The additive element X in the positive electrode active material 100 according to one aspect of the present invention is randomly and dilutely distributed inside. While their presence is acceptable, it is more preferable that some of them are segregated at the grain boundaries.

[0333] In other words, the grain boundaries and vicinity of the additive element X of the positive electrode active material 100 in one embodiment of the present invention The concentration of this substance is also preferably higher than that of other regions within the interior.

[0334] Grain boundaries can be considered as surface defects. Therefore, like particle surfaces, they are unstable. It is easy for this to occur and for changes in the crystal structure to begin. Therefore, the added elements at and near the grain boundaries are prone to this. A higher concentration of X can more effectively suppress changes in the crystal structure.

[0335] Furthermore, when the concentration of additive element X at and near the grain boundaries is high, the positive electrode activity of one embodiment of the present invention Even if a crack occurs along the grain boundary of 100 particles of material, the crack will The concentration of additive element X increases near the surface. Therefore, in the positive electrode active material after cracks have formed... This also improves corrosion resistance to hydrofluoric acid.

[0336] In this specification, the vicinity of a grain boundary refers to the region extending approximately 10 nm from the grain boundary. Let's do that.

[0337] <Particle size> If the particle size of the positive electrode active material 100 in one aspect of the present invention is too large, lithium diffusion becomes difficult. There are problems such as the surface of the active material layer becoming too rough when coated onto the current collector. On the other hand, if it is too small, it becomes difficult to support the active material layer when coating the current collector, and the reaction with the electrolyte... Problems such as excessive propagation can also arise. .) Preferably, the particle size is 1 μm or more and 100 μm or less, and preferably 2 μm or more and 40 μm or less. Preferably, the particle size is 5 μm or more and more preferably 30 μm or less.

[0338] <Analysis method> One embodiment of the present invention involves a positive electrode active material that exhibits an O3' type crystal structure when charged at a high voltage. Whether or not it is positive electrode active material 100 is determined by XRD, electron diffraction, and neutralization of the positive electrode charged with high voltage. By analyzing using methods such as sub-ray diffraction, electron spin resonance (ESR), and nuclear magnetic resonance (NMR), It can be determined. In particular, XRD can highly resolve the symmetry of transition metals such as cobalt in the positive electrode active material. It can analyze the crystallinity and crystal orientation, and compare the periodic strain and crystal structure of the lattice. Even if you measure the positive electrode obtained by disassembling a secondary battery directly, you can perform analysis at the Akiko size, and the measurement will be sufficiently accurate. It is preferable in that it allows for obtaining a certain degree of performance, among other things.

[0339] The positive electrode active material 100 in one aspect of the present invention is in a state where it is charged with a high voltage as described above. It has the characteristic of showing little change in crystal structure when discharged. Materials in which crystal structures exhibiting large changes in electrical state account for more than 50 wt% are resistant to high-voltage charging and discharging. It is undesirable because it cannot be obtained. And simply adding additive elements does not result in the desired crystal structure. It is important to note that this is not always the case. For example, cobalt containing magnesium and fluorine. Although they share the common characteristic of being lithium trioxide, when charged at high voltage, the O3' type crystal structure is different. When it exceeds 60 wt%, and when the H1-3 type crystal structure accounts for 50 wt% or more, Yes. Also, at a given voltage, the O3' type crystal structure becomes approximately 100 wt%, and furthermore, In some cases, an H1-3 type crystal structure may be formed when a predetermined voltage is increased. Therefore, one aspect of the present invention To determine whether or not it is a positive electrode active material 100, the crystal structure, including XRD, is examined. Further analysis is needed.

[0340] However, when the positive electrode active material is in a high-voltage charged or discharged state, its crystalline structure changes when exposed to the air. Changes in structure can occur. For example, a change from an O3' type crystal structure to an H1-3 type crystal structure may occur. This may occur. Therefore, all samples should be handled in an inert atmosphere such as an argon atmosphere. It is preferable to do so.

[0341] <Charging method> For determining whether a certain composite oxide is a positive electrode active material 100 according to one aspect of the present invention High-voltage charging, for example, uses a coin cell (CR2032 type, 20mm diameter) with a lithium counter electrode. It can be made (3.2mm in diameter) and charged.

[0342] More specifically, the positive electrode is a slurry made by mixing the positive electrode active material, conductive material, and binder. A positive electrode current collector made of aluminum foil coated with a special material can be used.

[0343] Lithium metal can be used as the counter electrode. However, if a material other than lithium metal is used as the counter electrode... When this occurs, the potential of the secondary battery and the potential of the positive electrode are different. The voltage and potential in this specification are Unless otherwise specified, this is the potential of the positive electrode.

[0344] The electrolyte in the electrolyte solution contains 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte used is ethylene carbonate (EC) and diethyl carbonate (DEC). EC:DEC = 3:7 (volume ratio), vinylene carbonate (VC) is mixed at 2 wt%. You can use the one that you have.

[0345] Polypropylene with a thickness of 25 μm can be used for the separator.

[0346] The positive electrode and negative electrode cans can be made of stainless steel (SUS). Cut.

[0347] The coin cell manufactured under the above conditions was charged with a constant current of 4.6V and 0.5C, and then the current value was measured. Charge at a constant voltage until the current reaches 0.01C. Here, 1C is defined as 137mA / g. The temperature should be set to 25°C. After charging in this manner, the coin cell is subjected to an argon atmosphere glow. By disassembling the device in a box and removing the positive electrode, a positive electrode active material charged with high voltage can be obtained. To suppress reactions with external components when performing various analyses afterward, the area is sealed in an argon atmosphere. It is preferable to do so. For example, XRD can be performed by sealing the sample in a sealed container under an argon atmosphere. can.

[0348] <xrd> The CuKα1 line is calculated from the models of the O3' type crystal structure and the H1-3 type crystal structure. The ideal powder XRD patterns are shown in Figures 13 and 15. For comparison, Li at x=1 The ideal XR calculated from the crystal structures of CoO2(O3) and CoO2(O1) at x=0 The D pattern is also shown. Note that the patterns for LiCoO2(O3) and CoO2(O1) are shown in IC. SD (Inorganic Crystal Structure Database) From the crystal structure information obtained, Materials Studio (BIOVIA) Using Reflex Powder Diffraction, one of the Joules Created. The range of 2θ is set to 15° to 75°, step size = 0.01, wavelength λ 1 = 1.540562 × 10 -10 m, λ2 not set, Monochromator is It was set to single. The crystal structure pattern of the O3' type crystal structure is the positive electrode activity of one embodiment of the present invention. The crystal structure is estimated from the XRD pattern of the material, and TOPAS ver.3 (Bruker Inc.) The XRD pattern was fitted using (crystal structure analysis software) and, as with the others, I created it.

[0349] As shown in Figure 13, in the O3' type crystal structure, 2θ = 19.30 ± 0.20° (19. (10° to 19.50°), and 2θ = 45.55 ± 0.10° (45.45° or more) Diffraction peaks appear below 45.65°. More specifically, 2θ = 19.30 ± 0.10° (between 19.20° and 19.40°), and 2θ = 45.55 ± 0.05° A sharp diffraction peak appears between 45.50° and 45.60°. However, as shown in Figure 15... As such, in the H1-3 type crystal structure and CoO2 (P-3m1, O1), P-3m1 is present at these positions. The 'ku' does not appear. Therefore, when charged at high voltage, 2θ = 19.30 ± 0.20°, The appearance of a peak at 2θ = 45.55 ± 0.10° indicates that the positive electrode activity of one embodiment of the present invention It can be said that this is one of the 100 characteristics of the substance.

[0350] This shows the XRD diffraction peaks in the crystal structure at x=1 and the crystal structure in the high-voltage charged state. It can also be said that the positions where they appear are close. More specifically, of the two main diffraction peaks of both, For one or more, more preferably three or more, the difference in the position where the peaks appear is 2θ = 0.7 It can be said that the degree is less than or equal to 2θ, and more preferably less than or equal to 2θ = 0.5°.

[0351] Furthermore, in one embodiment of the present invention, the positive electrode active material 100 exhibits an O3' type crystal structure when charged with a high voltage. However, not all of the positive electrode active material 100 has to have an O3' type crystal structure. It may contain or be partially amorphous. However, regarding the XRD pattern... When Rietveld analysis is performed, it is preferable that the O3' type crystal structure accounts for 50 wt% or more. It is more preferable that the content be 60 wt% or more, and even more preferable that it be 66 wt% or more. It is desirable that the O3' type crystal structure is present in 50 wt% or more, more preferably 60 wt% or more. Alternatively, if the content is 66 wt% or more, it can be used as a cathode active material with sufficiently excellent cycle characteristics. ru.

[0352] Furthermore, Rietveld analysis was performed even after more than 100 charge-discharge cycles from the start of measurement. When the O3' type crystal structure is present, it is preferable that it is 35 wt% or more, and preferably 40 wt% or more. This is more preferable, and even more preferable is 43 wt% or more.

[0353] Furthermore, the crystallite size of the O3'-type crystal structure possessed by the particles of the positive electrode active material is determined by the discharge state of Li It only drops to about 1 / 10th of the CoO2(O3) level. Therefore, it is the same as the positive electrode before charging and discharging. Even under XRD measurement conditions, a clear O3'-type crystal structure was observed in the high-voltage charging state. A 'k' can be observed. On the other hand, in simple LiCoO2, a portion adopts a structure similar to the O3' type crystal structure. Even if it were possible, the crystallite size would be smaller, and the peaks would be broader and smaller. The isx can be calculated from the full width at half maximum of the XRD peak.

[0354] In a positive electrode active material according to one aspect of the present invention, as described above, the influence of the Jahn-Teller effect is small. It is preferable that the positive electrode active material in one aspect of the present invention has a layered rock salt type crystalline structure and transition It is preferable that the transfer metal mainly consists of cobalt. Also, the positive electrode active in one aspect of the present invention In materials, if the effect of the Jahn-Teller effect is small, then in addition to cobalt, It may also contain the aforementioned additive element X.

[0355] Upon considering the preferred range of lattice constants, it was found that the positive electrode active material in one embodiment of the present invention... In this case, the positive state of the discharged state, which can be estimated from the XRD pattern, is the state of no charging or discharging. In the layered rock salt-type crystal structure of the highly active material particles, the lattice constant of the a-axis is 2.814× 10 -10 Larger than m, 2.817 × 10 -10 It is less than m and the lattice constant of the c axis is 1 4.05 × 10 -10 Larger than m, 14.07 × 10 -10 It is preferable that it is smaller than m. It was found that the state without charging and discharging is, for example, the powder before the positive electrode of a secondary battery is manufactured. This state is also acceptable.

[0356] Alternatively, the layered structure of the positive electrode active material particles in a non-charging / discharging state or in a discharged state. In a rock salt crystal structure, the lattice constant of the a-axis is the value obtained by dividing the lattice constant of the c-axis (a-axis / c-axis). It is preferable that the value is greater than 0.20000 and less than 0.20049.

[0357] Alternatively, the layered structure of the positive electrode active material particles in a non-charging / discharging state or in a discharged state. In rock salt crystal structures, when XRD analysis is performed, 2θ is 18.50° or greater than 19.30°. A first peak is observed below 38.00°, and a second peak is observed where 2θ is between 38.00° and 38.80°. A peak may be observed.

[0358] The peaks appearing in the powder XRD pattern represent the majority of the volume of the positive electrode active material 100. This reflects the crystal structure of the interior 100b of the positive electrode active material 100. (Surface layer 100a, etc.) The crystal structure can be analyzed by electron diffraction of the cross-section of the positive electrode active material 100.

[0359] <xps> X-ray photoelectron spectroscopy (XPS) can detect depths of approximately 2 to 8 nm (usually around 5 nm) from the surface. Since analysis of the region up to this point is possible, for approximately half of the surface layer 100a, each element can be analyzed. The concentration can be analyzed quantitatively. Furthermore, narrow scan analysis can reveal the bonding state of the elements. It can analyze the state. Note that the quantitative accuracy of XPS is often around ±1 atomic percent, and the detection range is... The limit varies depending on the element, but it is approximately 1 atomic percent.

[0360] For example, when performing XPS analysis, monochromatic aluminum can be used as the X-ray source. It can be done. Also, the extraction angle can be set to, for example, 45°.

[0361] Furthermore, when XPS analysis was performed on the positive electrode active material 100 according to one embodiment of the present invention, fluorine and other The peak indicating the elemental bond energy is preferably between 682 eV and 685 eV. Furthermore, it is even more preferable that the voltage be around 684.3 eV. This is because of the bonded lithium fluoride Energy of 685 eV, and the bond energy of magnesium fluoride of 686 eV. It is a value different from any of the above. In other words, the positive electrode active material 100 of one aspect of the present invention contains fluorine. In this case, it is preferable that the bond is one other than lithium fluoride and magnesium fluoride.

[0362] Furthermore, when XPS analysis was performed on the positive electrode active material 100 according to one embodiment of the present invention, magnesium The peaks indicating the bond energy between M and other elements are between 1302 eV and 1304 eV. It is preferable that the voltage be around 1303 eV. This is because magnesium fluoride This value is different from the binding energy of magnesium oxide, which is 1305 eV. This value is close to the combined energy. In other words, the positive electrode active material 100 of one aspect of the present invention is magnesium If a bond is present, it is preferable that the bond is one other than magnesium fluoride.

[0363] Preferably, additive elements X that are abundant in the surface layer 100a include magnesium and a The concentration of luminium, as measured by XPS, etc., is determined by ICP-MS (Inductively Coupled Plasma Mass Spectrometry). ), or higher than the concentration measured by GD-MS (glow discharge mass spectrometry), etc. preferable.

[0364] Magnesium and aluminum are processed to expose their cross-sections, and the cross-sections are then subjected to TEM-E When analyzing using DX, the concentration in the surface layer 100a is higher than the concentration in the interior layer 100b. This is preferable. Processing can be carried out, for example, by FIB.

[0365] In XPS (X-ray photoelectron spectroscopy) analysis, the number of magnesium atoms is equal to the number of cobalt atoms. It is preferable that the ratio is between 0.4 and 1.5 times. On the other hand, the ratio obtained by analysis of ICP-MS is... The ratio of nesium atoms, Mg / Co, is preferably between 0.001 and 0.06.

[0366] On the other hand, nickel contained in the transition metal is not concentrated in the surface layer 100a, but is distributed throughout the positive electrode active material 100 It is preferable that it is distributed throughout the body. However, there are regions where the aforementioned excess additive element X is unevenly distributed. This does not apply if they are present.

[0367] <Surface roughness and specific surface area> In one aspect of the present invention, the positive electrode active material 100 preferably has a smooth surface with few irregularities. A smooth surface with few irregularities indicates a good distribution of the added element X in the surface layer 100a. This is one factor that indicates goodness. Furthermore, in the manufacturing process of the positive electrode active material 100, Lithium cobaltate or nickel-cobalt-manganate before the addition of element X When initial heating is performed on thium, the repeated charge-discharge characteristics at high voltage are significantly superior. Therefore, it is particularly preferred as the positive electrode active material 100.

[0368] Furthermore, because the surface of the positive electrode active material 100 is smooth and has few irregularities, the positive electrode active material 100 This could improve surface stability and potentially suppress the formation of pits.

[0369] A smooth surface with few irregularities is, for example, a cross-sectional SEM image of the positive electrode active material 100 or This can be determined from cross-sectional TEM images, the specific surface area of ​​the positive electrode active material 100, etc.

[0370] For example, the surface smoothness of the positive electrode active material 100 can be quantified from a cross-sectional SEM image as shown below. It is possible.

[0371] First, the positive electrode active material 100 is processed using FIB or the like to expose its cross-section. At this time, a protective film is applied. It is preferable to cover the positive electrode active material 100 with a protective agent or the like. Next, the protective film and the positive electrode active material 100 An SEM image of the interface is taken. Noise reduction is applied to the SEM image using image processing software. After applying Gaussian blur (σ=2), the image is binarized. Furthermore, interface extraction is performed using image processing software. Perform the following: Furthermore, use a magic hand tool or similar to check the interface between the protective film and the positive electrode active material 100. Select the option and extract the data into a spreadsheet program. Use the functions of the spreadsheet program to perform regression. The curve (quadratic regression) is corrected, and the parameters for calculating roughness are obtained from the slope-corrected data. Next, we calculate the root mean square (RMS) surface roughness by determining the standard deviation. Therefore, the positive electrode active material has a surface roughness of at least 400 nm around the outer edge of the particles.

[0372] In this embodiment, the particle surface of the positive electrode active material 100 is roughness, which is an index of roughness. The mean square (RMS) surface roughness is 10 nm or less, less than 3 nm, preferably less than 1 nm, and further Preferably, the root mean square (RMS) surface roughness is less than 0.5 nm. .

[0373] The image processing software used for noise reduction, interface extraction, etc., is not particularly limited, but for example... For example, "ImageJ" can be used. Also, there are no particular restrictions on the use of spreadsheet software, etc. However, you can use Microsoft Office Excel, for example. .

[0374] For example, the actual specific surface area A measured by the gas adsorption method using the constant-volume method. R And the ideal ratio surface area A i From this ratio, the surface smoothness of the positive electrode active material 100 can be quantified. ru.

[0375] Ideal specific surface area A i This means that all particles have the same diameter as D50 and the same weight. The calculation is performed assuming the shape is an ideal sphere.

[0376] The median diameter D50 is measured using a particle size analyzer that employs laser diffraction and scattering methods. This can be done. Specific surface area can be measured using, for example, a specific surface area measuring device that uses the gas adsorption method by constant volume. Therefore, it can be measured.

[0377] In one aspect of the present invention, the positive electrode active material 100 has an ideal specific surface determined from the median diameter D50. Product A i And the actual specific surface area A R Ratio A R / A i It is preferable that the value is between 1 and 2.

[0378] The contents of this embodiment can be freely combined with the contents of other embodiments.

[0379] (Embodiment 4) In this embodiment, the positive electrode or the positive electrode manufactured by the manufacturing method described in the previous embodiment is used. This section describes examples of various shapes of secondary batteries that have a negative electrode.

[0380] [Coin-type rechargeable battery] An example of a coin-type secondary battery will be described. Figure 18A shows a coin-type (single-layer flat type) battery. The following is an exploded perspective view of the battery; Figure 18B is an external view, and Figure 18C is a cross-sectional view thereof. Coin-type rechargeable batteries are mainly used in small electronic devices. In this specification, etc., coin This category of batteries includes button-type batteries.

[0381] In Figure 18A, the overlapping of the components (up / down relationship and positional relationship) is shown for clarity. As shown, it is a schematic diagram. Therefore, Figure 18A and Figure 18B are not perfectly identical corresponding diagrams. I haven't done that.

[0382] In Figure 18A, the positive electrode 304, separator 310, negative electrode 307, spacer 322, and washer are shown. The 312s are stacked. These are sealed with the negative electrode can 302 and the positive electrode can 301. In Figure 18A, the gasket for sealing is not shown. Spacer 322, washer When crimping the positive electrode can 301 and the negative electrode can 302, the 312 protects the inside or the position inside the can. It is used to fix the position. Spacer 322 and washer 312 are made of stainless steel. Alternatively, use insulating materials.

[0383] The positive electrode 304 is a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305. ru.

[0384] To prevent a short circuit between the positive and negative electrodes, a separator 310 and a ring-shaped insulator 313 are connected to the positive electrode 30 They are positioned to cover the sides and top of 4, respectively. Separator 310 is positioned from positive electrode 304 It also has a large floor area.

[0385] Figure 18B is a perspective view of the completed coin-type rechargeable battery.

[0386] The coin-type rechargeable battery 300 consists of a positive electrode casing 301 which also serves as the positive electrode terminal and a negative electrode casing which also serves as the negative electrode terminal. The can 302 is insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 consists of a positive electrode current collector 305 and a positive electrode active material layer 30 provided in contact with it. It is formed by 6. The negative electrode 307 is provided with the negative electrode current collector 308 and is set to be in contact with it. It is formed by the negative electrode active material layer 309. Furthermore, the negative electrode 307 is not limited to a laminated structure. Alternatively, lithium metal foil or a lithium-aluminum alloy foil may be used.

[0387] Furthermore, the positive electrode 304 and negative electrode 307 used in the coin-type secondary battery 300 are each active The material layer only needs to be formed on one side.

[0388] The positive electrode can 301 and negative electrode can 302 contain nickel and aluminum, which are corrosion-resistant to the electrolyte. Metals such as titanium, or alloys thereof, and alloys of these with other metals (e.g., steel Stainless steel, etc., can be used. In addition, nickel can be used to prevent corrosion caused by electrolytes, etc. And it is preferable to coat it with aluminum or the like. The positive electrode can 301 is a positive electrode 304 and a negative electrode can 302 is electrically connected to the negative electrode 307.

[0389] These negative electrode 307, positive electrode 304, and separator 310 are immersed in the electrolyte, as shown in Figure 18C. As shown, with the positive electrode can 301 at the bottom, the positive electrode 304, separator 310, negative electrode 307, and negative electrode can The 302s are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are compressed via the gasket 303. This allows us to manufacture coin-type rechargeable batteries 300.

[0390] The above configuration provides high capacity, high charge / discharge capacity, and excellent cycle characteristics. This can be used to create an excellent coin-type rechargeable battery 300. Note that the negative electrode 307 and the positive electrode 304 In the case of a secondary battery having a solid electrolyte layer in between, the separator 310 may be unnecessary. can.

[0391] [Cylindrical rechargeable battery] An example of a cylindrical secondary battery will be explained with reference to Figures 19A and 19B. Figure 19B is This is a schematic diagram showing the cross-section of a cylindrical secondary battery. The cylindrical secondary battery 616 is shown in Figure 1. As shown in 9A and Figure 19B, the top surface has a positive electrode cap (battery cover) 601, and the sides and The bottom has a battery can (outer casing) 602. These positive electrode cap 601 and battery can (outer casing) The can (602) is insulated by the gasket (insulating packing) 610.

[0392] Inside the hollow cylindrical battery can 602, there is a separator between the strip-shaped positive electrode 604 and the negative electrode 606. A battery element is provided wound with a 605 in between. Although not shown in the diagram, the battery element is It is wound around the core axis. Battery casing 602 is closed at one end and open at the other. The battery container 602 contains nickel, aluminum, titanium, and other materials that are corrosion-resistant to the electrolyte. The group, or alloys thereof, and alloys of these with other metals (e.g., stainless steel, etc.) It can be used. In addition, nickel and aluminum can be used to prevent corrosion by the electrolyte. It is preferable to cover the battery casing 602 with the following. Inside the battery casing 602, the positive electrode and the negative electrode The battery element, around which the separator is wound, is supported by a pair of opposing insulating plates 608 and 609. It is sandwiched. Also, the inside of the battery can 602 in which the battery element is installed contains a non-aqueous electrolyte (shown in the figure) (The electrolyte) is injected. The non-aqueous electrolyte is the same as that used in coin-type rechargeable batteries. can.

[0393] Since the positive and negative electrodes used in cylindrical storage batteries are wound, active material is formed on both sides of the current collector. It is preferable to do so. Note that in Figures 19A to 19D, the height of the cylinder is greater than the diameter of the cylinder. The illustration shows a large secondary battery 616, but it is not limited to this. The diameter of the cylinder is greater than the height of the cylinder. It could also be used as a large rechargeable battery. This configuration could, for example, help to miniaturize rechargeable batteries. It is possible.

[0394] By using the negative electrode 570a obtained in the above embodiment as the negative electrode 606, high capacity and The goal is to create a cylindrical secondary battery 616 with high charge / discharge capacity and excellent cycle characteristics. It is possible. Furthermore, the positive electrode active material composite 100z obtained in the above embodiment can be used as the positive electrode 604. This results in a cylindrical two-cylinder battery with high capacity, high charge / discharge capacity, and excellent cycle characteristics. The next battery can be 616.

[0395] The positive terminal (positive current collector lead) 603 is connected to the positive terminal 604, and the negative terminal 606 is connected to the negative terminal The child (negative current collector lead) 607 is connected. The positive terminal 603 and the negative terminal 607 are, Metal materials such as aluminum can be used. The positive terminal 603 is connected to the safety valve mechanism 6 13. The negative terminals 607 are resistance-welded to the bottom of the battery can 602. Safety valve mechanism 61 3 is a PTC element (Positive Temperature Coefficient). The positive electrode cap 601 is electrically connected via t)611. The safety valve mechanism 613 is When the internal pressure of the battery rises above a predetermined threshold, the electrical current between the positive electrode cap 601 and the positive electrode 604 This disconnects the gas connection. Furthermore, the PTC element 611 has resistance when the temperature rises. This is a thermal resistance element with increased resistance, which limits the current flow and prevents abnormal heat generation. The PTC element uses barium titanate (BaTiO3) semiconductor ceramics. The following can be used.

[0396] Figure 19C shows an example of the energy storage system 615. The energy storage system 615 consists of multiple secondary batteries 6 It has 16. The positive electrode of each secondary battery is connected to a conductor 624 separated by an insulator 625. They are in contact and electrically connected. Conductor 624 is connected to control circuit 620 via wiring 623. It is electrically connected to the other. Also, the negative terminal of each secondary battery is controlled via wiring 626. It is electrically connected to circuit 620. Control circuit 620 detects overcharging or over-discharging. A protective circuit or the like can be applied to prevent this.

[0397] Figure 19D shows an example of the energy storage system 615. The energy storage system 615 consists of multiple secondary batteries. It has 616, and multiple secondary batteries 616 are sandwiched between conductive plates 628 and 614. Multiple secondary batteries 616 are connected to conductive plates 628 and 614 by wiring 627, and electrical connections are made between them. They are connected in parallel or in series. It is also possible to do so. By configuring a power storage system 615 having multiple secondary batteries 616, It can extract a large amount of electricity.

[0398] Multiple secondary batteries 616 may be connected in parallel and then further connected in series.

[0399] A temperature control device may be provided between multiple secondary batteries 616. When this occurs, the temperature control device cools the battery, and if the secondary battery 616 is too cold, the temperature control device will turn off. The control device can heat the system. Therefore, the performance of the energy storage system 615 is affected by the ambient temperature. It becomes less susceptible to resonance.

[0400] Furthermore, in Figure 19D, the energy storage system 615 has wiring 621 and wiring to the control circuit 620. It is electrically connected via 622. Wiring 621 is connected to multiple secondary circuits via conductive plate 628. The wiring 622 is connected to the positive terminal of battery 616, and via the conductive plate 614 to the negative terminals of multiple secondary batteries 616. They are electrically connected to each other.

[0401] [Other structural examples of secondary batteries] Examples of secondary battery structures will be explained using Figures 20 and 21.

[0402] The secondary battery 913 shown in Figure 20A has terminals 951 and 952 inside the housing 930. It has a wound body 950. The wound body 950 is immersed in an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, and terminal 951 is in contact with the housing by using an insulating material or the like. It is not in contact with 930. Note that in Figure 20A, for convenience, the housing 930 is shown separately. However, in reality, the wound body 950 is covered by the housing 930, and terminals 951 and 952 are covered by the housing. It extends outside the body 930. The housing 930 is made of a metal material (for example, aluminum). ) or resin materials can be used.

[0403] Furthermore, as shown in Figure 20B, the housing 930 shown in Figure 20A is formed from multiple materials. This is also possible. For example, the secondary battery 913 shown in Figure 20B has housings 930a and 930b attached to it. The components are joined together, and the winding body 950 is provided in the area enclosed by the housing 930a and housing 930b. It is being done.

[0404] For the enclosure 930a, insulating materials such as organic resins can be used. In particular, the antenna By using a material such as organic resin on the surface where the na is formed, the electric field produced by the secondary battery 913 is created. This can suppress shielding. If the shielding of the electric field by the housing 930a is small, the housing 930a An antenna may be installed inside. For the housing 930b, for example, a metal material may be used. It is possible.

[0405] Furthermore, the structure of the wound body 950 is shown in Figure 20C. The wound body 950 is connected to the negative electrode 931 and It has a positive electrode 932 and a separator 933. The wound body 950 has a separator 933. The laminated sheet, in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other, is wound up. It is a body. Furthermore, the stacking of the negative electrode 931, the positive electrode 932, and the separator 933 is further Multiple layers can be stacked.

[0406] Furthermore, the secondary battery 913 has a wound body 950a as shown in Figures 21A to 21C. It is also possible. The wound body 950a shown in Figure 21A has a negative electrode 931, a positive electrode 932, and a separator. It has 933 and a negative electrode 931 has a negative electrode active material layer 931a. Positive electrode 932 has positive electrode active It has a material layer 932a.

[0407] By using the negative electrode 570a obtained in the above embodiment as the negative electrode 606, high capacity and The goal is to create a cylindrical secondary battery 616 with high charge / discharge capacity and excellent cycle characteristics. It is possible. Furthermore, the positive electrode active material composite 100z obtained in the above embodiment can be used as the positive electrode 932. This results in a secondary battery with high capacity, high charge / discharge capacity, and excellent cycle characteristics. It can be set to 13.

[0408] The separator 933 has a wider width than the negative electrode active material layer 931a and the positive electrode active material layer 932a. It has and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. It is. Also, the fact that the negative electrode active material layer 931a is wider than the positive electrode active material layer 932a is a safety feature. It is preferable in this respect. Furthermore, a coiled body 950a of this shape is preferable in terms of safety and productivity. stomach.

[0409] As shown in Figure 21B, the negative terminal is electrically connected to terminal 951. Terminal 951 is connected to terminal 9 It is electrically connected to terminal 11a. The positive terminal is also electrically connected to terminal 952. Terminal 952 It is electrically connected to terminal 911b.

[0410] As shown in Figure 21C, the coiled body 950a and the electrolyte are covered by the housing 930, secondary This becomes the battery 913. It is preferable to provide a safety valve, overcurrent protection element, etc., in the housing 930. The safety valve is a valve that opens the inside of the housing 930 at a predetermined internal pressure to prevent the battery from rupturing. .

[0411] As shown in Figure 21B, the secondary battery 913 may have multiple windings 950a. By using a larger number of wound bodies 950a, a secondary battery 913 with a larger charge / discharge capacity can be obtained. This is possible. Other elements of the secondary battery 913 shown in Figures 21A and 21B are shown in Figures 20A to 21B. The description of secondary battery 913 shown in 20C can be taken into consideration.

[0412] <Laminated rechargeable battery> Next, regarding an example of a laminate-type secondary battery, an example of its external appearance is shown in Figures 22A and 22B. Figures 22A and 22B show the positive electrode 503, negative electrode 506, separator 507, and outer casing 5 09, It has a positive lead electrode 510 and a negative lead electrode 511.

[0413] Figure 23A shows the external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is the positive electrode current collector 501 The positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. 03 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). Negative electrode 5 06 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. Furthermore, the negative electrode 506 is the region where the negative electrode current collector 504 is partially exposed, i.e., the tab region. It has the following characteristics. The area and shape of the tab regions of the positive and negative electrodes are not limited to the example shown in Figure 23A. I can't.

[0414] <Method for manufacturing laminated rechargeable batteries> Here, an example of a method for manufacturing a laminate-type secondary battery, as shown in Figure 22A, is presented. This will be explained using Figures 23B and 23C.

[0415] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. (As shown in Figure 23B) The negative electrode 506, separator 507, and positive electrode 503 are shown. Here, there are 5 sets of negative electrodes and 4 sets of positive electrodes. An example of its use in combination is shown. It can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode. Next, positive electrode 5 Bonding of tab regions 03 and bonding of positive lead electrode 510 to the tab region of the outermost positive electrode. Perform the following. For joining, ultrasonic welding, for example, may be used. Similarly, the tab area of ​​the negative electrode 506. The components are joined together, and the negative electrode lead electrode 511 is joined to the tab region of the outermost negative electrode.

[0416] Next, the negative electrode 506, separator 507, and positive electrode 503 are placed on the outer casing 509.

[0417] Next, as shown in Figure 23C, fold the outer casing 509 at the part indicated by the dashed line. The outer periphery of the exterior body 509 is joined. For joining, for example, heat compression bonding may be used. At this time, It is attached to a part (or one side) of the outer casing 509 so that an electrolyte can be added later. A blank area (hereinafter referred to as the entry point) is created.

[0418] Next, the electrolyte is introduced into the inside of the outer casing 509 through the inlet provided in the outer casing 509. The introduction of the electrolyte is preferably carried out under a reduced pressure atmosphere or an inert atmosphere. Finally, the inlet is joined. In this way, the laminate-type secondary battery 500 is manufactured. It is possible.

[0419] By using the negative electrode 570a obtained in the above embodiment as the negative electrode 606, high capacity and The goal is to create a cylindrical secondary battery 616 with high charge / discharge capacity and excellent cycle characteristics. It is possible. Furthermore, the positive electrode active material composite 100z obtained in the above embodiment can be used as the positive electrode 503. This results in a secondary battery with high capacity, high charge / discharge capacity, and excellent cycle characteristics. It can be set to 00.

[0420] [Example of a battery pack] An example of a secondary battery pack according to one embodiment of the present invention that can be wirelessly charged using an antenna is shown in Figure This will be explained using Figures 24A to 24C.

[0421] Figure 24A shows the external appearance of the secondary battery pack 531, which has a thin rectangular parallelepiped shape (thickness It can also be called a flat plate shape. Figure 24B illustrates the configuration of the secondary battery pack 531. This is a diagram. The secondary battery pack 531 has a circuit board 540 and a secondary battery 513. The secondary battery 513 has a label 529 attached to it. The circuit board 540 has a sticker 515. It is fixed in place by [something]. The secondary battery pack 531 also has an antenna 517.

[0422] The interior of the secondary battery 513 may have a structure with a wound body, or a structure with a laminated body. You may do so.

[0423] In the secondary battery pack 531, for example, as shown in Figure 24B, on the circuit board 540, It has a control circuit 590. The circuit board 540 is also electrically connected to terminal 514. The circuit board 540 also includes the antenna 517, the positive lead and negative lead of the secondary battery 513. One end of the lead, 551, is electrically connected to the other end of the positive and negative leads, 552.

[0424] Alternatively, as shown in Figure 24C, a circuit system 590 is provided on the circuit board 540. a and a circuit system 590b which is electrically connected to the circuit board 540 via terminal 514 It may have ,

[0425] Furthermore, the antenna 517 is not limited to a coil shape; for example, it may be linear or plate-shaped. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, induction An antenna such as an electrostatic antenna may be used. Alternatively, antenna 517 may be a flat conductor. Good. This flat conductor can function as one of the conductors for electric field coupling. And, as one of the two conductors of the capacitor, antenna 517 is used. This may also be done. This allows for the exchange of power not only through electromagnetic and magnetic fields, but also through electric fields. can.

[0426] The secondary battery pack 531 has a layer 519 between the antenna 517 and the secondary battery 513. Layer 519 has the function of shielding electromagnetic fields, for example, from secondary batteries 513. For example, a magnetic material can be used as layer 519.

[0427] The contents of this embodiment can be freely combined with the contents of other embodiments.

[0428] (Embodiment 5) In this embodiment, the positive electrode active material composite 100z obtained in the above embodiment is used for the entire This shows an example of how to fabricate a solid-state battery.

[0429] As shown in Figure 25A, a secondary battery 400 according to one aspect of the present invention comprises a positive electrode 410 and a solid electrolyte. It has a layer 420 and a negative electrode 430.

[0430] The positive electrode 410 has a positive electrode current collector 413 and a positive electrode active material layer 414. 4 has a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material 411 is as described above. The positive electrode active material composite 100z obtained in the embodiment is used. Also, the positive electrode active material layer 414 It may have a conductive material and a binder.

[0431] The solid electrolyte layer 420 has a solid electrolyte 421. The solid electrolyte layer 420 has a positive electrode 410. It is located between the positive electrode active material 411 and the negative electrode 430, and does not have either the positive electrode active material 411 or the negative electrode active material 431. It is a difficult area.

[0432] The negative electrode 430 has a negative electrode current collector 433 and a negative electrode active material layer 434. 4 has a negative electrode active material 431 and a solid electrolyte 421. The negative electrode active material layer 434 is a guide It may also contain electrical materials and a binder. Furthermore, metallic lithium may be used as the negative electrode active material 431. When used, it is not necessary to form particles, so as shown in Figure 25B, it does not have a solid electrolyte 421. The negative electrode 430 can be made. If metallic lithium is used for the negative electrode 430, the secondary battery 40 It is preferable that the energy density at 0 can be improved.

[0433] The solid electrolyte 421 in the solid electrolyte layer 420 may be, for example, a sulfide-based solid electrolyte. Oxide-based solid electrolytes, halide-based solid electrolytes, etc., can be used.

[0434] Sulfide-based solid electrolytes include thiolysicone-based (Li 10 GeP2S 12 Li 3.25 G e 0.25 P 0.75 S4, etc.), sulfide glass (70Li2S・30P2S5, 30Li 2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57 Li2S・38SiS2・5Li4SiO4, 50Li2S・50GeS2, etc.), sulfides Crystallized glass (Li7P3S 11 Li 3.25 P 0.95 Contains sulfides (S4, etc.). Solid electrolytes have materials with high conductivity, can be synthesized at low temperatures, and are relatively soft. Because it is soft, it has advantages such as the conductivity path being easily maintained even after charging and discharging.

[0435] Oxide-based solid electrolytes include materials having a perovskite-type crystal structure (La 2 / 3-x L i 3x Materials having a NASICON-type crystal structure (such as TiO3, etc.), Li 1-Y Al Y Ti2 -Y (PO4)3, etc.), materials having a garnet-type crystal structure (Li7La3Zr2O 12 etc.), materials having a LISICON-type crystal structure (Li 14 ZnGe4O 16 etc.), LLZ O (Li7La3Zr2O 12 ), oxide glasses (Li3PO4-Li4SiO4, 50 Li4SiO4·50Li3BO3, etc.), oxide crystallized glasses (Li 1.07 Al 0.6 9Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc.) are included. [[ID=

[34] ] Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0436] Halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiC l, LiBr, LiI, etc. Also, composite materials obtained by filling pores of porous aluminum oxide or porous silica with these halide-based solid electrolytes can also be used as solid electrolytes.

[0437] Also, different solid electrolytes may be mixed and used.

[0438] Among them, Li 1-x Al x Ti 2-x (PO4)3 (0 < x < 1) (hereinafter, LATP) contains aluminum and titanium, elements that the cathode active material used in the secondary battery 400 of one aspect of the present invention may have, and thus improves cycle characteristics. ​​This is desirable because it can be expected to have synergistic effects. Furthermore, it can be expected to improve productivity through process reduction. In this specification, the NASICON type crystal structure is defined as M2(XO4)3(M: In compounds represented by transition metals (X:S, P, As, Mo, W, etc.), the MO6 octahedron and This refers to a structure in which XO4 tetrahedra are arranged in three dimensions, sharing vertices.

[0439] [Shape of the outer casing and secondary battery] The casing of the secondary battery 400 according to one aspect of the present invention can be made of various materials and shapes. While this is possible, it is preferable that the positive electrode, solid electrolyte layer, and negative electrode have a function to pressurize them. .

[0440] For example, Figure 26 shows an example of a cell used to evaluate the materials of an all-solid-state battery.

[0441] Figure 26A is a schematic cross-sectional view of the evaluation cell, which consists of a lower member 761 and an upper member 7 62 and fixing screws or wing nuts 764 to secure them, and a retaining screw 763 By rotating it, the electrode plate 753 is pressed and the evaluation material is fixed in place. Stainless steel An insulator 766 is provided between the lower member 761, which is made of a material, and the upper member 762. Furthermore, there is an O-ring for sealing between the upper member 762 and the retaining screw 763. 765 is provided.

[0442] The evaluation material is placed on an electrode plate 751, surrounded by an insulating tube 752, and viewed from above. The electrode plate 753 is pressing down on the material. This is a magnified view of the area around the evaluation material. Figure 26B shows the visual view.

[0443] As an example of the evaluation material, we used a stacked configuration consisting of a positive electrode 750a, a solid electrolyte layer 750b, and a negative electrode 750c. This is shown, and a cross-sectional view is shown in Figure 26C. Note that the same location is shown in Figures 26A to 26C. The same sign is used.

[0444] The electrode plate 751 and lower member 761, which are electrically connected to the positive electrode 750a, It can be said that this corresponds to a terminal. Electrode plate electrically connected to the negative electrode 750c. The part 753 and the upper member 762 can be said to correspond to the negative electrode terminal. While applying pressure to the evaluation material via electrode plate 751 and electrode plate 753, the electrical resistance is measured. It can measure various things.

[0445] Furthermore, the outer casing of the secondary battery according to one embodiment of the present invention uses a package with excellent airtightness. Preferably, a ceramic package or a resin package can be used. Furthermore, when sealing the outer casing, it is necessary to block out outside air and create a sealed atmosphere, for example, a globe. It is preferable to perform this within a box.

[0446] Figure 27A shows an oblique view of a secondary battery according to one embodiment of the present invention, having an exterior and shape different from that of Figure 26. A visual view is shown. The secondary battery in Figure 27A has external electrodes 771 and 772 and multiple packages. It is sealed with an exterior body containing components.

[0447] Figure 27B shows an example of a cross-section cut along the dashed line in Figure 27A. Positive electrode 750a, solid-state battery The laminate having a decomposition layer 750b and a negative electrode 750c has an electrode layer 773a provided on a flat plate. A package member 770a, a frame-shaped package member 770b, and an electrode layer 773b on a flat plate. The package component 770c, which is provided with a packing mechanism, is enclosed and sealed by a packing mechanism. Cage members 770a, 770b, and 770c are made of insulating material, such as resin material and ceramic You can use a buck.

[0448] The external electrode 771 is electrically connected to the positive electrode 750a via the electrode layer 773a, and the positive electrode end It functions as a child. In addition, the external electrode 772 is electrically connected to the negative electrode 750c via the electrode layer 773b. It is electrically connected and functions as a negative terminal.

[0449] By using the positive electrode active material composite 100z obtained in the above embodiment, high energy This makes it possible to realize all-solid-state secondary batteries with high density and good output characteristics.

[0450] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0451] (Embodiment 6) This embodiment is a different example from Figure 19D, which is a cylindrical secondary battery. Figure 28C is used. Here's an example of how it can be applied to electric vehicles (EVs).

[0452] Electric vehicles have a first battery 1301a, 130 as the main secondary battery for propulsion. 1b and a second battery that supplies power to inverter 1312 for starting motor 1304 Battery 1311 is installed. The second battery 1311 is the cranking battery (starter) Also called a secondary battery. The second battery 1311 is high output and In that case, a large capacity is not so necessary, and the capacity of the second battery 1311 is the same as the first battery It is smaller compared to Ri1301a and 1301b.

[0453] The internal structure of the first battery 1301a is a wound type as shown in Figure 20A or Figure 21C. Alternatively, the stacked type shown in Figure 22A or Figure 22B may be used. Also, the first B Battery 1301a may also be an all-solid-state battery of Embodiment 5. First battery 130 By using the all-solid-state battery of Embodiment 5 in 1a, high capacity can be achieved and safety can be improved. Furthermore, it can be made smaller and lighter.

[0454] In this embodiment, the first batteries 1301a and 1301b are connected in parallel. The example shown is that three or more can be connected in parallel. Also, the first battery 1301a If sufficient power can be stored, the first battery 1301b is not necessary. By configuring a battery pack that includes a secondary battery, it is possible to extract a large amount of power. Multiple rechargeable batteries may be connected in parallel, in series, or in parallel. After being connected, they may be further connected in series. Multiple rechargeable batteries are also called a battery pack.

[0455] Furthermore, in the case of a rechargeable battery installed in a vehicle, a tool is used to interrupt the power supply from multiple rechargeable batteries. It has a service plug or circuit breaker that can shut off high voltage without being used, It is provided in battery 1301a.

[0456] Furthermore, the power from the first batteries 1301a and 1301b is mainly used to rotate the motor 1304. It is used to power 42V automotive components (electric power) via the DC-DC circuit 1306. (Power steering 1307, heater 1308, defogger 1309, etc.) It supplies power. Even when the rear wheel has a rear motor 1317, the first battery 13 01a is used to rotate the rear motor 1317.

[0457] Furthermore, the second battery 1311 is connected to 14V automotive components via the DC-DC circuit 1310. (Supplies power to audio 1313, power windows 1314, lights 1315, etc.) To give.

[0458] Furthermore, the first battery 1301a will be explained using Figure 28A.

[0459] Figure 28A shows an example where nine rectangular rechargeable batteries 1300 are combined into a single battery pack 1415. It also shows that nine rectangular rechargeable batteries 1300 are connected in series, with one electrode separated from the insulator. The first electrode is fixed with a fixing part 1413, and the second electrode is fixed with a fixing part 1414 made of an insulator. In this embodiment, an example is shown in which the battery is fixed with fixing parts 1413 and 1414. It may also be configured to house the vehicle in a container (also called an enclosure). Since it is expected that vibration or shaking will be applied, the fixing parts 1413, 1414 It is preferable to secure multiple secondary batteries in a battery housing box or the like. The pole is electrically connected to the control circuit unit 1320 by wiring 1421. The electrodes are electrically connected to the control circuit unit 1320 by wiring 1422.

[0460] Furthermore, the control circuit unit 1320 includes a memory circuit that includes a transistor using an oxide semiconductor. It may be used. A charge control circuit having a memory circuit including an oxide semiconductor transistor. A road or battery control system is called a BTOS (Battery operating system). In places where it is called tem, or Battery oxide semiconductor There is a match.

[0461] It is preferable to use a metal oxide that functions as an oxide semiconductor. For example, as In-M-Zn oxide (element M is aluminum, gallium, yttrium, copper, etc.) Nadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, Molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and It is preferable to use a metal oxide such as one or more selected from magnesium. In particular, In-M-Zn oxides that can be applied as oxides include CAAC-OS(C-Axis Al igned Crystal Oxide Semiconductor), CAC-O S(Cloud-Aligned Composite Oxide Semiconductor It is preferable that it be uctor. Also, as oxides, In-Ga oxide, In-Z n oxide may also be used. CAAC-OS has multiple crystalline regions, and these multiple crystalline regions The region is an oxide semiconductor in which the c-axis is oriented in a specific direction. The specific direction is CA. The thickness direction of the AC-OS film, the normal direction of the surface on which the CAAC-OS film is formed, or CAAC-O This is the normal direction to the surface of the S film. Furthermore, a crystalline region is a region with periodicity in its atomic arrangement. Furthermore, if we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region where the lattice arrangement is aligned. Furthermore, CAAC-OS has regions where multiple crystal regions are connected in the ab-plane direction. Furthermore, the region in question may have distortion. Distortion refers to the connection of multiple crystal regions. Within a region, between a region with a aligned grid arrangement and another region with a aligned grid arrangement, the grid arrangement This refers to the area where the orientation changes. In other words, CAAC-OS is c-axis oriented and ab-plane oriented It is an oxide semiconductor that does not have a clear orientation in the direction. Also, CAC-OS is, for example, The elements constituting the metal oxide are 0.5 nm to 10 nm, preferably 1 nm or larger. This is a material composition characterized by a predominance of particles smaller than or near 3 nm in size. Furthermore, in the following, In a metal oxide, one or more metal elements are unevenly distributed, and the region containing the metal element is 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or near that size. A mixture of these materials is sometimes called a mosaic or patchy appearance.

[0462] Furthermore, CAC-OS is a material that separates into a first region and a second region. This results in a zigzag-like structure, where the first region is distributed within the film (hereinafter also referred to as a cloud-like structure). ) In other words, CAC-OS is a mixture of the first region and the second region. It is a composite metal oxide having the following composition.

[0463] Here, I for the metal elements constituting CAC-OS in In-Ga-Zn oxide The atomic ratios of n, Ga, and Zn are given as [In], [Ga], and [Zn] respectively. To be expressed. For example, in CAC-OS in In-Ga-Zn oxide, the first region This is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. That is. Or, for example, in the first region, [In] is greater than [In] in the second region. It is also a region where the [Ga] is large, and the [Ga] is smaller than the [Ga] in the second region. Furthermore, in the second region, [Ga] is greater than [Ga] in the first region, and [I n] is a region where n is smaller than [In] in the first region.

[0464] Specifically, the first region mentioned above mainly consists of indium oxide, indium zinc oxide, etc. This is a region of minutes. Furthermore, the second region mentioned above is gallium oxide, gallium zinc oxide, etc. This is the region in which In is the main component. In other words, the first region described above can be said to be the region in which In is the main component. It can be replaced. Furthermore, the second region described above can be rephrased as the region with Ga as the main component. It is possible.

[0465] Note that a clear boundary may not be observed between the first region and the second region described above. .

[0466] For example, in CAC-OS in In-Ga-Zn oxide, the energy-dispersive X-ray segment Optical method (EDX:Energy Dispersive X-ray spectrosc) EDX mapping obtained using opy revealed the region with In as its main component (the first region) It has a structure in which a region (the second region) and a region mainly composed of Ga are unevenly distributed and mixed. This can be confirmed.

[0467] When CAC-OS is used in a transistor, the conductivity is due to the first region and the second region The insulating properties due to the region work complementarily to enable the switching function (On The function to turn off CAC-OS can be added to it. In other words, CAC-OS and The material has both conductive and insulating properties in parts, and the entire material Then it has the function of a semiconductor. By separating the conductive function and the insulating function, This allows for the maximum enhancement of both functions. Therefore, CAC-OS is used in transistors. This results in a high on-current (I on ), high field-effect mobility (μ), and good switching This enables smooth operation.

[0468] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention Oxide semiconductors include amorphous oxide semiconductors, polycrystalline oxide semiconductors, and a-like OS(a morphous-like Oxide Semiconductor), CAC-O S, nc-OS(nano crystalline Oxide Semiconductor It may have two or more of the following: ctor) and CAAC-OS.

[0469] Furthermore, since it can be used in high-temperature environments, the control circuit section 1320 uses an oxide semiconductor. It is preferable to use a transistor. To simplify the process, control circuit section 1 320 may be formed using a unipolar transistor. An oxide semiconductor is used for the semiconductor layer. The transistor has an operating ambient temperature range that is wider than that of a single-crystal Si transistor, above -40°C. The temperature is below 0°C, and even if the secondary battery overheats, the change in its characteristics is smaller compared to a single-crystal Si transistor. The off-current of an oxide semiconductor transistor is below the detection limit even at 150°C. However, the off-current characteristics of a single-crystal Si transistor are highly temperature-dependent. For example, 1 At 50°C, the off-current of a single-crystal Si transistor increases, and the current on / off ratio becomes sufficiently large. It does not work. The control circuit unit 1320 can improve safety. Also, the aforementioned practical The positive electrode active material composite 100z obtained in this form is combined with a secondary battery that uses it as the positive electrode. This results in a synergistic effect regarding safety.

[0470] The control circuit section 1320, which uses a memory circuit including an oxide semiconductor transistor, To address instability issues such as micro-short circuits, it functions as an automatic control device for secondary batteries. It is also possible to do the following: Functions to eliminate the causes of instability in secondary batteries include overcharging prevention and overvoltage prevention. Prevents current flow, controls overheating during charging, balances cells in the battery pack, prevents over-discharge, includes a battery level indicator, and is temperature-sensitive. Automatic control of charging voltage and current, charging current control according to the degree of degradation, micro short circuit Examples include normal behavior detection and anomaly prediction related to micro-short circuits, and of these, at least The control circuit unit 1320 has one function. Furthermore, the automatic control device for the secondary battery is being miniaturized. It is possible.

[0471] Furthermore, a microshort refers to a tiny short circuit inside a secondary battery. It's not a short circuit between the positive and negative terminals of the battery that would render it impossible to charge or discharge, but rather a very small short circuit. This refers to the phenomenon where a small short-circuit current flows in a particular area. It occurs for a relatively short time and is slight. Even in a single location, large voltage changes can occur, and these abnormal voltage values ​​can affect subsequent estimations. There is a risk of causing harm.

[0472] One of the causes of microshorts is the positive electrode active material being damaged by multiple charge-discharge cycles. Due to the uneven distribution, localized current concentration occurs in parts of the positive and negative electrodes, causing separation. A part of the device may stop functioning, or side reactions may cause byproducts to be generated, resulting in microscopic damage. It is said that a short circuit has occurred.

[0473] In addition to detecting micro-shorts, the control circuit unit 1320 also detects the terminal power of the secondary battery. It can also be said that it detects pressure and manages the charging and discharging state of the secondary battery. For example, to prevent overcharging. The output transistor and the cutoff switch of the charging circuit are both turned off almost simultaneously. can.

[0474] Furthermore, an example of a block diagram of the battery pack 1415 shown in Figure 28A is shown in Figure 28B.

[0475] The control circuit unit 1320 includes at least a switch to prevent overcharging and a switch to prevent over-discharging. A switch unit 1324 including a switch, and a control circuit 1322 that controls the switch unit 1324. The control circuit unit 1320 has a voltage measuring unit for the first battery 1301a. The secondary battery has upper and lower voltage limits set, and the input current from an external source and the external source The output current is limited. Use is recommended within the range between the lower and upper voltage limits of the secondary battery. The voltage is within the recommended range; if it falls outside that range, the switch unit 1324 activates and protects the system. It functions as a circuit. In addition, the control circuit unit 1320 controls the switch unit 1324 to release the overload. It can also be called a protection circuit to prevent overcharging. For example, a voltage that is likely to cause overcharging. When the control circuit 1322 detects this, the switch on the switch unit 1324 is turned off. The current is interrupted. Furthermore, a PTC element is provided in the charge / discharge path to control the current in accordance with the rise in temperature. A function to block the signal may be provided. In addition, the control circuit unit 1320 has an external terminal 1325 (+I It has N) and an external terminal 1326(-IN).

[0476] The switch section 1324 uses an n-channel transistor and a p-channel transistor. It can be constructed by combining the components. The switch section 1324 uses single-crystal silicon. Switches are not limited to those having Si transistors, but for example, those using Ge (germanium), S iGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium Aluminum arsenic, InP (indium phosphide), SiC (silicon carbide), Z nSe (zinc selenide), GaN (gallium nitride), GaO x (Gallium oxide; x is 0) The switch section 1324 may be formed using a power transistor having a large real number (or similar). Furthermore, memory elements using OS transistors can be placed on circuits using Si transistors, etc. Because it can be freely arranged by stacking, integration can be easily achieved. Transistors can be manufactured using the same manufacturing equipment as Si transistors. Therefore, it can be manufactured at low cost. That is, an OS transistor is used on the switch section 1324. The control circuit unit 1320 can be stacked and integrated into a single chip. Since the volume occupied by the circuit section 1320 can be reduced, miniaturization becomes possible.

[0477] The first batteries, 1301a and 1301b, are primarily used to power 42V (high-voltage) in-vehicle equipment. The second battery 1311 supplies power to 14V (low-voltage) in-vehicle equipment. ru.

[0478] In this embodiment, both the first battery 1301a and the second battery 1311 are supplied with lithium An example using a um-ion secondary battery is shown. The second battery 1311 is a lead-acid battery, an all-solid-state battery. A pond or an electric double-layer capacitor may be used. For example, the all-solid-state battery of Embodiment 5 It may be used. By using the all-solid-state battery of Embodiment 5 for the second battery 1311, high capacity It can be made more compact and lighter.

[0479] Furthermore, the regenerative energy from the rotation of the tire 1316 is transmitted to the motor 1 via the gear 1305. It is sent to 304, and the motor controller 1303 and battery controller 1302 The second battery 1311 is then charged via the control circuit unit 1321. The controller 1302 charges the first battery 1301a via the control circuit unit 1320. Alternatively, the first is transmitted from the battery controller 1302 via the control circuit unit 1320. The battery 1301b is charged. In order to efficiently charge the regenerative energy, the first It is desirable that batteries 1301a and 1301b are capable of rapid charging.

[0480] The battery controller 1302 controls the charging voltage of the first batteries 1301a and 1301b. The charging current and other parameters can be set. The battery controller 1302 uses By setting charging conditions according to the charging characteristics of the secondary battery, rapid charging can be achieved.

[0481] Also, although not shown in the diagram, when connecting to an external charger, the charger's outlet or The charger's connection cable is electrically connected to the battery controller 1302. Power supplied from the charger is sent to the first battery via the battery controller 1302. Charges 1301a and 1301b. Also, some chargers have a control circuit. Although the functions of the battery controller 1302 may not be used, to prevent overcharging... It is preferable to charge the first batteries 1301a and 1301b via the control circuit unit 1320. It seems that the charger's outlet or the charger's connection cable also has a control circuit. In some cases, the control circuit unit 1320 is an ECU (Electronic Control Unit). It is sometimes called an ECU (Control Unit). An ECU is a control unit installed in electric vehicles. It connects to the (Oller Area Network). CAN is used as the in-vehicle LAN. It is one of the serial communication standards. Furthermore, an ECU includes a microcomputer. Furthermore, the ECU uses either a CPU or a GPU.

[0482] External chargers installed at charging stations, etc., use 100V outlets and 200V outlets. There are various types, such as contactless power supply systems, 3-phase 200V and 50kW. Additionally, external power supply systems such as contactless power supply are available. It can also be charged by receiving power from a charging facility.

[0483] For fast charging, a secondary battery that can withstand high-voltage charging is required to achieve rapid charging in a short time. Batteries are needed.

[0484] Furthermore, the secondary battery of this embodiment described above is a composite of positive electrode active materials obtained in the above embodiment. It uses combined 100z. Furthermore, graphene is used as a conductive material, and the electrode layer is made thicker. By suppressing capacity reduction even with a high load and maintaining high capacity, a significant synergistic effect is achieved, resulting in a substantial increase in electricity consumption. This enables the creation of secondary batteries with improved characteristics. It is particularly effective for secondary batteries used in vehicles. Without increasing the weight ratio of the secondary battery to the total weight, the cruising range is extended, specifically We can provide vehicles with a driving range of 500km or more on a single charge.

[0485] In particular, the secondary battery of this embodiment described above is a positive electrode active material composite as described in the previous embodiment. By using a 100z battery, the operating voltage of the secondary battery can be increased, and the charging voltage can be increased. Accordingly, the usable capacity can be increased. Also, the correct described in the above embodiment By using the 100z electrode active material composite as the positive electrode, a secondary battery for vehicles with excellent cycle characteristics is developed. It can be provided.

[0486] Next, we will describe an example in which a secondary battery, which is one aspect of the present invention, is implemented in a vehicle, typically a transport vehicle. I will explain.

[0487] Furthermore, the vehicle is equipped with a secondary battery as shown in one of Figures 19D, 21C, or 28A. and hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (P It can realize next-generation clean energy vehicles such as hybrid vehicles (HV). It can also be used for agricultural machinery and electric assist systems. Motorized bicycles including scooters, motorcycles, electric wheelchairs, electric carts, small or large boats Ships, submarines, aircraft such as fixed-wing and rotary-wing aircraft, rockets, satellites, space probes, and other aircraft. Secondary batteries can also be mounted on transport vehicles such as star probes and spacecraft. One aspect of the present invention The secondary battery can be a high-capacity secondary battery. Therefore, one embodiment of the present invention is a secondary battery It is suitable for miniaturization and weight reduction, and can be suitably used in transport vehicles.

[0488] In Figures 29A to 29D, an example of a mobile body using one aspect of the present invention is shown, for transport Let's look at an example of a vehicle. The automobile 2001 shown in Figure 29A uses an electric motor as its power source for driving. It is an electric vehicle that uses a motor. Alternatively, it uses an electric motor and an engine as the power source for driving. This is a hybrid vehicle that can be appropriately selected and used. It is equipped with a secondary battery. In this case, the example of the secondary battery shown in Embodiment 4 is installed in one or more locations. Figure 2 The automobile 2001 shown in 9A has a battery pack 2200, and the battery pack has multiple secondary batteries It has a secondary battery module connected to a pond. Furthermore, it is electrically connected to the secondary battery module. It is preferable to have a charging control device.

[0489] Furthermore, the automobile 2001 has a plug-in type and non- It can be charged by receiving power from an external charging facility using a contact power supply method, etc. Regarding power supply, charging methods and connector specifications are based on CHAdeMO® or CHAdeMO®. This can be done appropriately using the prescribed method, such as a battery charger. It can be an external power source, or a household power source. For example, by using plug-in technology, external The power supply from this source can charge the battery storage device installed in the 2001 vehicle. Electricity is generated by converting alternating current (AC) power to direct current (DC) power via a conversion device such as an AC / DC converter. It is possible.

[0490] Although not shown in the diagram, a power receiving device is mounted on the vehicle, and power is supplied wirelessly from a ground-based power transmission device. It can also be charged by supplying power. In this contactless power supply method, power transmission equipment is installed on the road or exterior wall. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. Power can be transmitted and received between two vehicles using a contact-to-power method. Solar panels may be installed on both exterior parts to charge the secondary battery while the vehicle is stopped and in motion. For contactless power supply like this, electromagnetic induction or magnetic resonance methods can be used. Cut.

[0491] Figure 29B shows a large transport vehicle equipped with an electrically controlled motor, as an example of a transport vehicle. It indicates 2002. The secondary battery module of the transport vehicle 2002 has a nominal voltage of 3.0 Four secondary batteries with a voltage between 5.0V and 17V are used as cell units, and 48 cells are connected in series. The maximum voltage is set to 0V. The secondary batteries that make up the secondary battery module of battery pack 2201 Aside from differences in the number of elements, it has the same functions as Figure 29A, so the explanation will be omitted.

[0492] Figure 29C shows, as an example, a large transport vehicle 2003 equipped with an electrically controlled motor. This indicates that the secondary battery module of the transport vehicle 2003 has a nominal voltage of 3.0V or more, for example. The maximum voltage will be 600V, achieved by connecting more than 100 secondary batteries with a voltage of 0V or less in series. By using the negative electrode 570a obtained in this form as the negative electrode, high capacity and high charge / discharge capacity are achieved. Furthermore, it is possible to create a cylindrical secondary battery 616 with excellent cycle characteristics. Also, as mentioned above... Using a secondary battery in which the positive electrode active material composite 100z described in the embodiment is used as the positive electrode. Therefore, secondary batteries with good rate characteristics and charge / discharge cycle characteristics can be manufactured, and transportation This can contribute to improving the performance and extending the lifespan of vehicle 2003. Also, battery pack 22 Aside from the difference in the number of secondary batteries that make up the secondary battery module 02, it is the same as Figure 29A. Since it has the necessary functions, I will omit the explanation.

[0493] Figure 29D shows, as an example, an aircraft 2004 with a fuel-burning engine. The aircraft 2004 shown in Figure 29D is a type of transport vehicle because it has wheels for takeoff and landing. However, by connecting multiple rechargeable batteries, a rechargeable battery module is constructed, and the rechargeable battery module It has a battery pack 2203 that includes a battery and a charging control device.

[0494] The secondary battery module for the aircraft 2004, for example, consists of eight 4V secondary batteries connected in series. The maximum voltage is 32V. The secondary batteries that make up the secondary battery module of battery pack 2203. Aside from differences in the number of elements, it has the same functions as Figure 29A, so the explanation will be omitted.

[0495] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0496] (Embodiment 7) In this embodiment, Figure 3 shows an example of implementing a secondary battery, which is one aspect of the present invention, in a building. This will be explained using Figures 0A and 30B.

[0497] The house shown in Figure 30A is an energy storage device 2612 having a secondary battery, which is one embodiment of the present invention. It has a solar panel 2610. The energy storage device 2612 is connected to the solar panel 2610 and wiring It is electrically connected via 2611, etc. Also, the energy storage device 2612 and the ground-mounted charging Device 2604 may be electrically connected. The power obtained from the solar panel 2610 is The energy storage device 2612 can be charged. Furthermore, the power stored in the energy storage device 2612 is... The secondary battery of the vehicle 2603 can be charged via the charging device 2604. The device 2612 is preferably installed in the underfloor space. This allows for more effective use of the space above the floor. Alternatively, the energy storage device 2612 is above the floor. It can also be installed in [location].

[0498] The electricity stored in the energy storage device 2612 is used to power other electronic devices in the house. This is possible. Therefore, even when power cannot be supplied from the commercial power source due to a power outage, this power By using the energy storage device 2612 according to one embodiment of the invention as an uninterruptible power supply, the use of electronic equipment is It becomes possible.

[0499] Figure 30B shows an example of an energy storage device according to one aspect of the present invention. As shown in Figure 30B, An energy storage device 791 according to one aspect of the present invention is installed in the underfloor space 796 of object 799. Furthermore, the power storage device 791 may be provided with the control circuit described in Embodiment 6. By using the negative electrode 570a obtained in the embodiment described above as the negative electrode, a high capacity and charge / discharge capacity can be achieved. This allows for the creation of a cylindrical secondary battery 616 with high capacity and excellent cycle characteristics. Furthermore, a secondary battery using the positive electrode active material composite 100z obtained in the above embodiment as the positive electrode is used. By using it in the electrical device 791, a long-life energy storage device 791 can be made.

[0500] The energy storage device 791 is equipped with a control device 790, and the control device 790 is connected by wiring That is, the distribution board 703, the energy storage controller 705 (also called the control unit), and the display unit 706. It is electrically connected to router 709.

[0501] Power is supplied from the commercial power supply 701 to the distribution panel 703 via the service drop connection section 710. Furthermore, power is supplied to the distribution board 703 from the energy storage device 791 and the commercial power supply 701. The distribution board 703 receives the power and, via outlets (not shown), loads the general load 707. It also supplies power to the energy storage system load 708.

[0502] General load 707 is, for example, electrical equipment such as televisions and personal computers. The energy storage load 708 is, for example, an electrical appliance such as a microwave oven, refrigerator, or air conditioner.

[0503] The energy storage controller 705 includes a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 measures the general load 707 and the energy storage during a day (for example, from 0:00 to 24:00). It has a function to measure the amount of electricity consumed by the system load 708. In addition, the measurement unit 711 has a function to measure the amount of energy stored. It has the function of measuring the amount of electricity used by device 791 and the amount of electricity supplied from the commercial power supply 701. It is also acceptable to do so. In addition, the prediction unit 712 predicts the general load 707 and the energy storage system load 70 during the day. Based on the amount of electricity consumed in 8, the general load 707 and the energy storage system load 708 during the next day It has a function to predict the amount of electricity demanded to be consumed. In addition, the planning unit 713 has a function to predict the forecasting unit 712 It has the function of planning the charging and discharging of the energy storage device 791 based on the predicted amount of electricity demand. .

[0504] The electricity consumed by the general load 707 and the energy storage system load 708 as measured by the measurement unit 711 The power level can be checked by the display unit 706. Also, via the router 709, This can also be confirmed in electrical equipment such as Levi and personal computers. Furthermore, via Router 709, mobile electronic devices such as smartphones and tablets can access the network. It can also be confirmed by the display unit 706, electrical equipment, and portable electronic terminals. The forecasting unit 712 also checks the predicted electricity demand for each time period (or hourly). It is possible.

[0505] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0506] (Embodiment 8) This embodiment shows an example of mounting an energy storage device according to one aspect of the present invention on a motorcycle or bicycle. vinegar.

[0507] Figure 31A shows an example of an electric bicycle using a power storage device according to one embodiment of the present invention. An energy storage device according to one embodiment of the present invention can be applied to the electric bicycle 8700 shown. One embodiment of the energy storage device includes, for example, a plurality of storage batteries and a protection circuit.

[0508] The electric bicycle 8700 is equipped with a power storage device 8702. The power storage device 8702 provides power to the driver. It can supply electricity to the motor that is being operated. Also, the energy storage device 8702 is portable. This can be done, and Figure 31B shows the state after it has been removed from the bicycle. Also, the energy storage device 8702 is The energy storage device according to one aspect of the present invention has multiple storage batteries 8701 built in, and the battery The remaining charge and other information can be displayed on the display unit 8703. Furthermore, the energy storage device 8702 is designed to display actual Control circuit 8704 capable of charging control or abnormality detection of a secondary battery, as illustrated in embodiment 6. It has. The control circuit 8704 is electrically connected to the positive and negative terminals of the storage battery 8701. Furthermore, the control circuit 8704 is equipped with a small solid-state secondary battery as shown in Figures 27A and 27B. Alternatively, a small solid-state rechargeable battery, as shown in Figures 27A and 27B, may be provided in the control circuit 8704. This allows the control circuit 8704 to retain data in its memory circuit for an extended period of time by supplying power. It can also be supplied. Furthermore, the positive electrode active material composite 100z obtained in the above embodiment can be used as a positive electrode active material composite. By combining it with the secondary battery used at the electrode, a synergistic effect on safety can be obtained. A secondary battery and control circuit 8 using the positive electrode active material composite 100z obtained in the embodiment as the positive electrode. The 704 can make a significant contribution to eliminating accidents such as fires caused by secondary batteries.

[0509] Furthermore, Figure 31C shows an example of a motorcycle using an energy storage device according to one embodiment of the present invention. The scooter 8600 shown includes a power storage device 8602, side mirrors 8601, and turn signals 86 It is equipped with 03. The energy storage device 8602 can supply electricity to the turn signal light 8603. Furthermore, a secondary battery using the positive electrode active material composite 100z obtained in the above embodiment as the positive electrode. The energy storage device 8602, which houses multiple such devices, can have a high capacity and contribute to miniaturization. can.

[0510] Furthermore, the scooter 8600 shown in Figure 31C has a power storage device 8602 in the under-seat storage compartment 8604. It can store the following. The power storage device 8602 can store even if the under-seat storage 8604 is small. It can be stored in the under-seat storage compartment 8604.

[0511] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0512] (Embodiment 9) This embodiment describes an example of mounting a secondary battery, which is one aspect of the present invention, into an electronic device. To clarify, electronic devices that implement secondary batteries include, for example, television equipment (television, or Television receivers (also called television receivers), computer monitors, digital cameras, digital cameras Video cameras, digital photo frames, mobile phones (also known as mobile phones or mobile phone devices) (u) Portable game consoles, personal information terminals, sound playback devices, and large game machines such as pachinko machines. Examples include notebook personal computers and tablet computers. These include terminals, e-readers, and mobile phones.

[0513] Figure 32A shows an example of a mobile phone. The mobile phone 2100 is housed in a casing 2101. In addition to the built-in display unit 2102, there are operation buttons 2103, an external connection port 2104, and a speaker. It is equipped with a microphone 2106, etc. Furthermore, the mobile phone 2100 is a secondary power supply. It has a pond 2107. The positive electrode active material composite 100z described in the above embodiment is the positive electrode By incorporating the secondary battery 2107 used in this device, high capacity can be achieved, and the casing can be made smaller. This allows for a configuration that can accommodate space-saving requirements.

[0514] The mobile phone 2100 is a mobile phone that can make calls, send emails, read and create documents, play music, and interact with other devices. - It can run various applications such as network communication and computer games. ru.

[0515] The operation button 2103 is used for setting the time, as well as turning the power on and off, turning wireless communication on, and more. Various functions such as operation, activation and deactivation of silent mode, and activation and deactivation of power saving mode. It can be made to hold. For example, the operating system built into the mobile phone 2100 The stem also allows you to freely configure the function of the operation button 2103.

[0516] Furthermore, the mobile phone 2100 is capable of performing standardized short-range wireless communication. Yes, for example, by communicating with a wireless headset, hands-free operation is possible. You can also make phone calls.

[0517] Furthermore, the mobile phone 2100 is equipped with an external connection port 2104, and can connect to other information terminals. Data can be exchanged directly via this. Also, via external connection port 2104... It can also be charged wirelessly. Note that the charging operation is performed wirelessly without going through the external connection port 2104. It may also be done by electricity.

[0518] The mobile phone 2100 preferably has a sensor. For example, a fingerprint sensor. Human body sensors such as pulse sensors and body temperature sensors, touch sensors, pressure sensors, and acceleration sensors. It is preferable that the following are installed:

[0519] Figure 32B shows an unmanned aerial vehicle 2300 having multiple rotors 2302. The 300 is sometimes called a drone. The unmanned aerial vehicle 2300 is one aspect of the present invention. It has a secondary battery 2301, a camera 2303, and an antenna (not shown). Unmanned aerial vehicle The 2300 can be remotely controlled via an antenna. The positive result obtained in the above embodiment Secondary batteries using the 100z electrode active material composite as the positive electrode have high energy density and high safety. Therefore, it can be used safely for extended periods of time, and is a secondary system mounted on the Unmanned Aerial Vehicle 2300. It is suitable as a battery.

[0520] Figure 32C shows an example of a robot. The robot 6400 shown in Figure 32C is secondary Battery 6409, light sensor 6401, microphone 6402, upper camera 6403, Peeker 6404, display unit 6405, lower camera 6406 and obstacle sensor 6407, It is equipped with a dynamic mechanism 6408, a computing device, and the like.

[0521] Microphone 6402 has the function of detecting the user's voice and ambient sounds, etc. Furthermore, speaker 6404 has the function of emitting sound. Robot 6400 is microf To communicate with the user using the phone 6402 and speaker 6404. This is possible.

[0522] The display unit 6405 has the function of displaying various information. The robot 6400 is used It is possible to display the information desired by the user on the display unit 6405. The display unit 6405 is a touch It may also be equipped with a control panel. Furthermore, the display unit 6405 is a removable information terminal. It's also fine to install it in a fixed position on the robot 6400 for charging and data transfer. This makes it possible.

[0523] The upper camera 6403 and the lower camera 6406 image the area around the robot 6400. It has the function of. In addition, the obstacle sensor 6407 uses the moving mechanism 6408 to move the robot 64 Robot 6 can detect the presence or absence of obstacles in the direction of travel as 00 moves forward. The 400 uses an upper camera 6403, a lower camera 6406, and an obstacle sensor 6407. This allows them to perceive their surroundings and move safely.

[0524] The robot 6400 has a secondary battery 6409 according to one aspect of the present invention and a semiconductor in its internal region. It comprises a body device or electronic components. The positive electrode active material composite 100z obtained in the above embodiment Secondary batteries using this material as the positive electrode have high energy density and high safety, and can be used for long periods of time. It allows for safe use over long periods and is suitable as the secondary battery 6409 to be installed in the robot 6400. be.

[0525] Figure 32D shows an example of a cleaning robot. The cleaning robot 6300 has a housing 630 1 Display unit 6302 located on the top surface, multiple cameras 6303 located on the side, brush 6 It has components 304, an operation button 6305, a secondary battery 6306, various sensors, etc. Although not present, the 6300 cleaning robot is equipped with wheels, a suction nozzle, etc. The Bot 6300 is self-propelled, detects debris 6310, and removes debris from the suction port located on its underside. It can be used for suction.

[0526] For example, the cleaning robot 6300 analyzes images captured by the camera 6303 to identify walls, furniture, etc. Alternatively, it can determine the presence or absence of obstacles such as steps. Furthermore, image analysis can determine wiring... If an object that may become entangled in brush 6304 is detected, the rotation of brush 6304 will be stopped. The cleaning robot 6300 has a secondary battery according to one aspect of the present invention in its internal region. 6306 and a semiconductor device or electronic component are provided. The positive electrode active material obtained in the above embodiment Secondary batteries using 100z composite material as the positive electrode have high energy density and high safety. It allows for safe use over long periods of time, and is a rechargeable battery installed in the 6300 cleaning robot. It is suitable as 6306.

[0527] Figure 33A shows an example of a wearable device. A wearable device is powered by A rechargeable battery is used. In addition, when the user uses it in daily life or outdoors, splash-proof To enhance performance, water resistance, or dust resistance, the wired connector portion is exposed. Wearable devices that can be charged not only by hand but also wirelessly are desired.

[0528] For example, in a spectacle-type device 4000 as shown in Figure 33A, a secondary power supply according to one aspect of the present invention is provided. It can be equipped with a pond. The glasses-type device 4000 consists of a frame 4000a and a display unit. It has a 4000b. A rechargeable battery is installed in the temple of the curved frame 4000a. This results in a lightweight, well-balanced, and long-lasting pair of glasses-type devices. It can be set to 000. The positive electrode active material composite 100z obtained in the above embodiment is positive The secondary batteries used in the electrodes have high energy density, and are suitable for space saving due to the miniaturization of the housing. It is possible to realize the desired configuration.

[0529] Furthermore, the headset-type device 4001 is equipped with a secondary battery according to one aspect of the present invention. This is possible. The headset-type device 4001 includes at least a microphone unit 4001a and It has a flexible pipe 4001b and an earphone section 4001c. A secondary battery can be installed in 4001b or in the earphone section 4001c. A secondary battery using the positive electrode active material composite 100z obtained in this embodiment as the positive electrode is high energy This density allows for a configuration that can accommodate space savings due to the miniaturization of the enclosure. .

[0530] Furthermore, a secondary battery according to one aspect of the present invention is provided in a device 4002 that can be directly attached to the body. It can be installed. Inside the slim housing 4002a of device 4002, a secondary battery 40 02b can be provided. The positive electrode active material composite 100z obtained in the above embodiment The secondary battery used as the positive electrode has a high energy density, and is suitable for space saving due to the miniaturization of the housing. It is possible to realize a configuration that can accommodate this.

[0531] Furthermore, a secondary battery, which is one embodiment of the present invention, is mounted on a device 4003 that can be attached to clothing. It is possible. The secondary battery 4003 is located inside the slim housing 4003a of device 4003. b can be provided. The positive electrode active material composite 100z obtained in the above embodiment is used as the positive electrode. The secondary battery used has a high energy density and is suitable for space saving due to the miniaturization of the housing. It is possible to realize a configuration that can be achieved.

[0532] Furthermore, a secondary battery according to one aspect of the present invention can be mounted on the belt-type device 4006. The belt-type device 4006 consists of a belt section 4006a and a wireless power supply / receiving section 4 It has 006b, and a secondary battery can be mounted in the internal region of the belt portion 4006a. A secondary battery using the positive electrode active material composite 100z obtained in the above embodiment as the positive electrode is high energy Energy density, and a configuration that can accommodate space saving due to the miniaturization of the enclosure. can.

[0533] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the wristwatch-type device 4005. The watch-type device 4005 has a display unit 4005a and a belt unit 4005b. A secondary battery can be provided in the display unit 4005a or the belt unit 4005b. A secondary battery using the positive electrode active material composite 100z obtained in this embodiment as the positive electrode is high energy This density allows for a configuration that can accommodate space savings due to the miniaturization of the enclosure. .

[0534] The display unit 4005a displays not only the time, but also various other information such as incoming emails and phone calls. It can be shown.

[0535] Furthermore, the wristwatch-type device 4005 is a wearable device that is worn directly on the wrist. Since it is a device, it may be equipped with sensors to measure the user's pulse, blood pressure, etc. It can accumulate data on quantity and health, allowing for health management.

[0536] Figure 33B shows a perspective view of the wristwatch-type device 4005 after it has been removed from the arm.

[0537] A side view is also shown in Figure 33C. Figure 33C shows the secondary battery 913 built into the internal region. This shows the state of being. The secondary battery 913 is the secondary battery shown in Embodiment 4. The pond 913 is located in a position that overlaps with the display unit 4005a, and is high density and high capacity. It is compact and lightweight.

[0538] In the case of the wristwatch-type device 4005, it is required to be small and lightweight. The positive electrode active material composite 100z obtained in the above embodiment is used as the positive electrode of the secondary battery 913. This makes it possible to create a secondary battery 913 that is both high in energy density and compact.

[0539] Figure 33D shows an example of wireless earphones. Here, a pair of main units 4100a and The diagram shows wireless earphones having the main unit 4100b, but they do not necessarily have to be a pair. stomach.

[0540] The main units 4100a and 4100b include the driver unit 4101, the antenna 4102, It has a secondary battery 4103. It may also have a display unit 4104. It may also have a wireless IC or the like. It is preferable that the device has a circuit board, charging terminals, etc. It may also have a microphone. .

[0541] Case 4110 contains a secondary battery 4111. It also contains a wireless IC, a charging control IC, etc. It is preferable that the circuit board has a circuit board and charging terminals. It is also preferable that it has a display unit, buttons, etc. That's fine.

[0542] The main units 4100a and 4100b communicate wirelessly with other electronic devices such as smartphones. This allows sound data and other information sent from other electronic devices to be transmitted to the main unit 4100a and It can be played back with the 4100b. Also, the 4100a and 4100b units have microphones. If available, the sound acquired by the microphone can be sent to other electronic devices and processed by those electronic devices. The audio data can be sent back to the main units 4100a and 4100b for playback. For example, it can also be used as a translation device.

[0543] Furthermore, the secondary battery 4111 in case 4110 is transferred to the secondary battery in main unit 4100a. 4103 can be charged. As secondary batteries 4111 and 4103 The coin-type secondary battery, cylindrical secondary battery, etc., described in the previous embodiment can be used. The secondary battery obtained in this form has a high energy density, and secondary battery 4103 and secondary battery By using it in pond 4111, it can address the space-saving requirements associated with the miniaturization of wireless earphones. This configuration can be realized.

[0544] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0545] In this embodiment, a negative electrode according to one aspect of the present invention was fabricated, and the fabricated negative electrode was evaluated.

[0546] <Fabrication of the negative electrode> The negative electrode was fabricated following the flow shown in Figure 7. As silicon-containing particles, ALDRI CH nanosilicon particles were used. Linyi Gelon was used as the graphite-containing particle. New Battery Materials uses MCMB-G10 artificial graphite particles. It was used. Graphene oxide was used as the graphene compound. Toray Industries, Inc. used polyimide. A polyimide precursor manufactured by [company name] was used.

[0547] Electrode GS1 was fabricated as the negative electrode. Steps S61, S72, S80, and in Figure 7 The weight ratio of the materials prepared in S87 was: artificial graphite particles: nanosilicon particles: graphite oxide The weight ratio of the polyimide precursor was set to 82.8:9.2:5:3. Note that artificial graphite particles were also used. The weight ratio of the material to the nanosilicon particles is 9:1.

[0548] Nanosilicon particles and a solvent were prepared and mixed (steps S61 and S62 in Figure 7). S63). NMP was used as the solvent. Mixing was done with a rotational mixer (Awatori Rentaro, TH). Mixing was performed at 2000 rpm for 3 minutes using INKY Co., Ltd., and the mixture was recovered to obtain mixture E-1 (Figure). Step 7 (S64, S65).

[0549] Next, artificial graphite particles were prepared and mixed with mixture E-1 (steps S72, S7 in Figure 7). 3) Mixing is performed using a rotary-orbit mixer at 2000 rpm for 3 minutes, then collected and mixed into mixture E. -2 was obtained (steps S74 and S75 in Figure 7).

[0550] Next, mixture E-2 and the graphene compound were repeatedly mixed while adding solvent. As the graphene compound, graphene oxide was prepared, and the mixing was done using a rotational mixer. The mixture was mixed at 2000 rpm for 3 minutes and then collected (steps S80, S81, and S82 in Figure 7). Next Next, the recovered mixture is kneaded into a solid mass, NMP is added as needed, and then a rotational-orbital mixer is used. Mixed at 2000 rpm for 3 minutes and then collected (steps S83, S84, and S8 in Figure 7) 5) Steps S83 to S85 were repeated five times to obtain mixture E-3. (Step S86 in Figure 7).

[0551] Next, mixture E-3 was mixed with the polyimide precursor (step S88 in Figure 7). Mixing was performed using a rotation-orbit mixer at 2000 rpm for 3 minutes. After that, NMP was prepared. Prepare the mixture, add it to adjust the viscosity (step S89 in Figure 7), and then mix further. (Mixed twice at 2000 rpm for 3 minutes in a rotary-orbit mixer), collected and used as a slurry, then mixed. E-4 was obtained (steps S90, S91, S92 in Figure 7).

[0552] Next, the current collector was prepared and coated with mixture E-4 (steps S93 and S94 in Figure 7). ). Prepare a copper foil with a thickness of 18 μm as the current collector, and mix E-3 with a gap thickness of 100 Using a μm doctor blade, mixture E-4 was coated onto copper foil.

[0553] Next, the copper foil coated with mixture E-4 was subjected to a first heating at 50°C for 1 hour (Figure 7). Step S95). Then, a second heating is performed under reduced pressure at 400°C for 5 hours (Figure 7). Step S96) yielded an electrode. Heating reduced the graphene oxide, decreasing the amount of oxygen. do.

[0554] <sem> SEM observation was performed on the surface of the fabricated electrodes. The SEM used was a Hitachi High-Technologies S4. 800 was used. The acceleration voltage was set to 5kV.

[0555] Figures 34A and 34B show observed images of the surface of electrode GS1. In the SEM images, nano The silicon particles exhibit a relatively bright contrast.

[0556] Figure 34B is a magnified image of the surface of electrode GS1. The particles are approximately 5 μm to 15 μm in size. Multiple nanosilicon particles, approximately 50 nm to 250 nm in size, are present on the surface of the graphite particles. These multiple nanosilicon particles are covered with graphene (reduced graphene oxide). A region was observed where nanosilicon particles and graphene were pr...

Claims

1. A lithium-ion secondary battery having a positive electrode, a negative electrode, an electrolyte, and a separator, The negative electrode comprises a first negative electrode active material containing silicon particles, a second negative electrode active material containing graphite with a larger particle size than the silicon particles, and a graphene compound. The first negative electrode active material is in contact with the second negative electrode active material, and the graphene compound is in surface contact with the first negative electrode active material and the second negative electrode active material. In the first negative electrode active material, at least a portion of the surface of the silicon particles is terminated with a hydroxyl group, The graphene compound has pores with 9 or more members. The graphene compound has a plurality of carbon atoms that constitute the pore, One or more of the aforementioned carbon atoms are terminated with a fluorine atom. Lithium-ion rechargeable battery.

2. In claim 1, The graphene compound is in contact with the first negative electrode active material and the second negative electrode active material in such a manner that it clings to them. Lithium-ion rechargeable battery.

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