Lithium-ion rechargeable battery

Abstract

To provide a positive electrode active material with high capacity and good cycle characteristics. [Solution] The positive electrode active material is designed to show little change in its crystal structure between the charged and discharged states. For example, in the discharged state, it has a layered rock salt-type crystalline structure, and when charged with a high voltage of about 4.6V... In its state, the positive electrode active material having a pseudo-spinel type crystal structure is more responsive than known positive electrode active materials. The crystal structure and volume change little before and after discharge. When analyzed by XRD, 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0 A diffraction peak occurs at 0.10°.

Description

Technical Field

[0001] One aspect of the present invention relates to an object, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or a manufacturing method thereof. In particular, it relates to a positive electrode active material that can be used in a secondary battery, a secondary battery, and an electronic device having the secondary battery.

[0002] In this specification, the power storage device refers to all elements and devices having a power storage function. For example, it includes storage batteries (also referred to as secondary batteries) such as lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors.

[0003] In this specification, an electronic device refers to all devices having a power storage device. An electro-optical device having a power storage device, an information terminal device having a power storage device, etc. are all electronic devices.

Background Art

[0004] In recent years, various power storage devices such as lithium ion secondary batteries, lithium ion capacitors, and air batteries have been actively developed. In particular, lithium ion secondary batteries with high output and high energy density are rapidly expanding in demand along with the development of the semiconductor industry for portable information terminals such as mobile phones, smartphones, or notebook computers, portable music players, digital cameras, medical devices, next-generation clean energy vehicles (hybrid vehicles (HEV), electric vehicles (EV), plug-in hybrid vehicles (PHEV), etc.). As a source of supply, it has become indispensable in today's information society.

[0005] The characteristics required of lithium-ion secondary batteries include further increases in energy density, These improvements include enhanced cycle characteristics, safety in various operating environments, and improved long-term reliability.

[0006] Therefore, in order to improve the cycle characteristics and increase the capacity of lithium-ion secondary batteries, positive electrode activity Improvements to the material are being considered (Patent Document 1, Patent Document 2, and Non-Patent Document 1). Also, correct Research has also been conducted on the crystal structure of the highly active material (Non-Patent Documents 2 to 4). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2006-164758 [Patent Document 2] Special Publication No. 2014-523840 [Non-patent literature]

[0008] [Non-Patent Document 1] Jae-Hyun Shim et al, “Characterization of Spinel LixCo2O4-Coated LiCoO2 Prepared with Post-Thermal Treatment as a Cathode Material for Lithium Ion Batteries”, CHEMISTRY OF MATERIALS, 2015, 27, pp.3273-3279 [Non-Patent Document 2] Toyoki Okumura et al, “Correlation of lithium ion distribution and X-ray absorption near-edge structure in O3-and O2-lithium cobalt oxides from first-principle calculation”, Journal of Materials Chemistry, 2012, 22, pp.17340-17348 [Non-Patent Document 3] Motohashi, T. et al, “Electronic phase diagram of the layered cobalt oxide system LixCoO2 (0.0≦x≦1.0)”, Physical Review B, 80(16);165114 [Non-Patent Document 4] Zhaohui Chen et al, “Staging Phase Transitions in LixCoO2”, Journal of The Electrochemical Society, 2002, 149(12) A1604-A1609 [Overview of the project] [Problems that the invention aims to solve]

[0009] One aspect of the present invention is a lithium-ion secondary battery with even higher capacity and excellent charge-discharge cycle characteristics. One objective of this invention is to provide a positive electrode active material for a pond. Alternatively, one aspect of this invention is lithium When used in ion secondary batteries, the decrease in capacity during charge-discharge cycles is suppressed. One of the objectives is to provide a material. Alternatively, one aspect of the present invention relates to a high-capacity secondary battery. One of the objectives of this invention is to provide a secondary battery with excellent charge and discharge characteristics. One aspect of this invention provides a secondary battery with excellent charge and discharge characteristics. One of the objectives is to provide a safe or highly reliable secondary power supply. One of the objectives is to provide a pond.

[0010] Alternatively, one aspect of the present invention relates to a novel substance, active material particles, energy storage device, or a method for producing the same. One of the objectives is to provide [this].

[0011] Furthermore, the description of these problems does not preclude the existence of other problems. The embodiments do not need to solve all of these problems. It is possible to extract other issues from the description of the requested terms. [Means for solving the problem]

[0012] To solve the above problems, a positive electrode active material according to one aspect of the present invention is provided in both a charged state and a discharged state. It is characterized by minimal change in crystal structure.

[0013] One aspect of the present invention is a secondary battery having a positive electrode and a negative electrode, wherein the XRD pattern of the positive electrode When analyzed by the Rietveld method, the positive electrode has a pseudo-spinel crystal structure, and pseudo-spinel This is a secondary battery in which the proportion of the type crystal structure is 60 wt% or more.

[0014] Another aspect of the present invention relates to lithium, cobalt, magnesium, oxygen, fluorine, A positive electrode active material having the positive electrode active material used as the positive electrode and lithium metal used as the negative electrode. In a lithium-ion secondary battery, the current value is measured until the battery voltage reaches 4.6V in a 25°C environment. After charging to a sufficiently low level, the positive electrode was analyzed by powder X-ray diffraction using CuKα1 rays. Diffraction peaks are observed at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. It is a positive electrode active material that possesses [a certain characteristic].

[0015] Another aspect of the present invention relates to lithium, cobalt, magnesium, oxygen, fluorine, A positive electrode active material having the following characteristics, wherein the abundance ratio of the positive electrode active material with a charging depth of 0.8 or higher is 60 w The volume per unit cell of the crystal structure with t% or more, and the positive electrode activity of a charge depth of 0.06 or less. The volume per unit cell of a crystalline structure having an abundance of 60 wt% or more in a substance, and The positive electrode active material has a difference of 2.5% or less.

[0016] In the above, it is preferable that the positive electrode active material has at least one of Ti or Al. [Effects of the Invention]

[0017] According to one aspect of the present invention, a lithium-ion secondary battery with high capacity and excellent charge-discharge cycle characteristics is provided. It can provide a positive electrode active material. Furthermore, by using it in a lithium-ion secondary battery, This provides a positive electrode active material that suppresses capacity degradation during charge-discharge cycles. Furthermore, it is possible to provide high-capacity secondary batteries. In addition, it is possible to provide secondary batteries with excellent charge and discharge characteristics. It can be provided. Furthermore, it can provide safe and reliable secondary batteries. Furthermore, it is possible to provide novel materials, active material particles, energy storage devices, or methods for producing them. ru.

[0018] Furthermore, the description of these effects does not preclude the existence of other effects. The form does not need to have all of these effects. Other effects are described in the specification. This will become clear from the descriptions in the drawings and claims, and the specification, drawings, and claims will be clear from the description, drawings, and claims. It is possible to extract other effects from any of these descriptions. [Brief explanation of the drawing]

[0019] [Figure 1] A diagram illustrating the charging depth and crystal structure of a positive electrode active material according to one embodiment of the present invention. [Figure 2] A diagram illustrating the charging depth and crystal structure of a conventional positive electrode active material. [Figure 3] XRD pattern calculated from crystal structure. [Figure 4] A diagram illustrating the crystal structure and magnetism of a positive electrode active material according to one embodiment of the present invention. [Figure 5] A diagram illustrating the crystal structure and magnetism of a conventional positive electrode active material. [Figure 6] Cross-sectional view of the active material layer when a graphene compound is used as a conductive additive. [Figure 7] A diagram illustrating how to charge a rechargeable battery. [Figure 8] A diagram illustrating how to charge a rechargeable battery. [Figure 9] A diagram illustrating the discharge method of a secondary battery. [Figure 10] A diagram illustrating a coin-type rechargeable battery. [Figure 11] A diagram illustrating a cylindrical rechargeable battery. [Figure 12] A diagram illustrating an example of a secondary battery. [Figure 13] A diagram illustrating an example of a secondary battery. [Figure 14] A diagram illustrating an example of a secondary battery. [Figure 15] A diagram illustrating an example of a secondary battery. [Figure 16] A diagram illustrating a laminated rechargeable battery. [Figure 17] A diagram illustrating a laminated rechargeable battery. [Figure 18] A diagram showing the external appearance of a secondary battery. [Figure 19] A diagram showing the external appearance of a secondary battery. [Figure 20] A diagram illustrating the method for manufacturing a secondary battery. [Figure 21] A diagram illustrating a rechargeable battery that can be bent. [Figure 22] A diagram illustrating a rechargeable battery that can be bent. [Figure 23]A diagram illustrating an example of an electronic device. [Figure 24] A diagram illustrating an example of an electronic device. [Figure 25] A diagram illustrating an example of an electronic device. [Figure 26] A diagram illustrating an example of an electronic device. [Figure 27] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 28] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 29] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 30] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 31] XRD pattern of the positive electrode active material of the comparative example of Example 1. [Figure 32] XRD pattern of the positive electrode active material of the comparative example of Example 1. [Figure 33] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 34] XRD pattern of a positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 35] XRD pattern of the positive electrode active material of the comparative example of Example 1. [Figure 36] XRD patterns of the positive electrode active material of one embodiment of the present invention in Example 1 and a comparative example. [Figure 37] A graph showing the volume change rate of the positive electrode active material according to one embodiment of the present invention in Example 1. [Figure 38] Cycle characteristics of a secondary battery of one embodiment of the present invention in Example 1 and a comparative example. [Figure 39] ESR signals of the positive electrode active material of one embodiment of the present invention in Example 2 and a comparative example. [Figure 40] ESR signals of the positive electrode active material of one embodiment of the present invention in Example 2 and a comparative example. [Figure 41] The crystal structure model used in the calculations for Example 3. [Figure 42] A graph illustrating the calculation results for Example 3. [Figure 43] A graph illustrating the calculation results for Example 3. [Modes for carrying out the invention]

[0020] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is... Not limited to the following description, the form and details can be modified in various ways, as any person skilled in the art would know. This is easily understood. Furthermore, the present invention shall be interpreted as being limited to the contents of the embodiments described below. It's not something that can be done.

[0021] Furthermore, in this specification, crystal planes and directions are indicated by Miller indices. Table of crystal planes and directions In crystallography, numbers are preceded by a superscript bar, but in this specification, due to limitations on application notation, numbers are not preceded by a superscript bar. Sometimes, instead of placing a bar above the number, 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 < >The individual planes that represent crystal planes are ( ), and the set of planes with equivalent symmetry are {}. To express

[0022] In this specification, segregation refers to the process of a solid composed of multiple elements (e.g., A, B, C) This refers to the phenomenon in which a certain element (for example, B) is distributed non-uniformly in space.

[0023] In this specification, the surface layer of particles such as active material refers to the region from the surface up to approximately 10 nm. It can also be said that surfaces created by cracks or fissures are considered surfaces. Furthermore, the region deeper than the surface layer is called a surface. It's called the interior.

[0024] In this specification, etc., the layered rock salt type crystal structure of a composite oxide containing lithium and a transition metal This structure has a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and it contains transition metals and Because lithium is arranged in a regular pattern to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. This refers to the crystal structure. It may contain defects such as vacancies in cations or anions. Also, layers... Strictly speaking, the rock salt crystal structure is a structure in which the lattice of the rock salt crystal is distorted. be.

[0025] Furthermore, in this specification, 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 contains certain elements. It is also acceptable for there to be deficiencies in cations or anions.

[0026] Furthermore, in this specification, etc., the pseudo-spinel type of composite oxide containing lithium and a transition metal The crystal structure is R-3m, and although it is not a spinel-type crystal structure, cobalt, Magnesium and other ions occupy the 6-coordinate position of oxygen, and the ion arrangement is symmetrical, similar to that of a spinel. This refers to a crystal structure that possesses certain properties. Note that pseudo-spinel crystal structures are typically found in light elements such as lithium. It can occupy the oxygen 4-coordinate position, and in this case as well, the ion arrangement exhibits a symmetry similar to that of the spinel type. It holds.

[0027] Furthermore, the pseudo-spinel type crystal structure has Li randomly placed between the layers, but is a CdCl2 type 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.

[0028] Layered rock salt crystals, and the anions of rock salt crystals, have a cubic close-packed structure (face-centered cubic lattice structure). It takes this form. It is also presumed that in pseudo-spinel crystals, the anions adopt a cubic close-packed structure. When they come into contact, there exists a crystal plane in which the orientation of the cubic close-packed structure composed of anions is aligned. However, the space group of layered rock salt crystals and pseudo-spinel crystals is R-3m, and rock salt crystals The space groups of crystals Fm-3m (the space group of typical rock salt crystals) and Fd-3m (the simplest space group) Because it is different from the space group of rock salt crystals with symmetry, the mirror of the crystal plane that satisfies the above conditions The index differs between layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals. In layered rock salt crystals, pseudo-spinel crystals, and rock salt crystals, the structure is composed of anions. When the orientations of the resulting cubic close-packed structure are aligned, it can be said that the crystal orientations are roughly the same. be.

[0029] The approximate agreement of the crystal orientation in the two regions can be seen in TEM (transmission electron microscope) images and STEM images. (Scanning transmission electron microscope) image, HAADF-STEM (High-angle scattering annular dark-field scanning transmission electron microscope) This can be determined from images such as microscopic images and ABF-STEM (annular bright-field scanning transmission electron microscope) images. Yes, it is possible. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc., can also be used as criteria for judgment. If the crystal orientation is roughly consistent, then cations and anions can be seen linearly in TEM images, etc. It was observed that the difference in direction between the alternatingly arranged columns was 5 degrees or less, more preferably 2.5 degrees or less. Yes, it is possible. However, light elements such as oxygen and fluorine cannot be clearly observed in TEM images, etc. In some cases, however, the alignment of the metal elements can be determined by their arrangement.

[0030] Furthermore, in this specification, the theoretical capacity of the positive electrode active material refers to the insertable and removable capacity of the positive electrode active material. This refers to the amount of electricity that would be generated if all lithium were to be desorbed. For example, the theoretical capacity of LiCoO2 is 27 The theoretical capacity of LiNiO2 is 274mAh / g, and the theoretical capacity of LiMn2O4 is 4mAh / g. The capacity is 148mAh / g.

[0031] Furthermore, in this specification, etc., the charging depth when all insertable and removable lithium is inserted. Let 0 be the charge depth when all the insertable and detachable lithium in the positive electrode active material has been detached, and 1 be the charge depth when 0 is the charge depth when 1 is the charge depth when all the insertable and detachable lithium in the positive electrode active material has been detached. Let's leave it at that.

[0032] Furthermore, in this specification, charging refers to the transfer of lithium ions from the positive electrode to the negative electrode within the battery. This refers to the movement of electrons from the negative electrode to the positive electrode in an external circuit. In this context, the process of releasing lithium ions is called charging. Also, when the charging depth exceeds 0.5 Let the positive electrode active material be defined as a charged positive electrode active material. Furthermore, the charge depth is 0.8 or greater. Let the positive electrode active material be defined as a positive electrode active material that has been charged with a high voltage. For example, Li If the charge level is 219.2mAh / g or higher in CoO2, the positive electrode is charged at high voltage. It is the active material. Also, lithium cobalt oxide (here, impurities) has an impurity element content of 5 at% or less. In a 25°C environment, the element (which refers to elements other than lithium, cobalt, and oxygen) is electrically charged. Constant current charging is performed until the battery voltage reaches 4.6V (in the case of lithium counter electrode), and then the current value is reduced to 0. The positive electrode active material after constant voltage charging until it reaches 01C is also the same as the positive electrode active material charged at high voltage. Let's do that.

[0033] Similarly, discharge is the movement of lithium ions from the negative electrode to the positive electrode within a battery, and external circuits This refers to the transfer of electrons from the positive electrode to the negative electrode. The positive electrode active material is lithium. The insertion of ions is called discharge. Also, the positive electrode active material with a charge depth of 0.5 or less is discharged. This refers to a positive electrode active material with a charge depth of 0.06 or less, or a high The positive electrode active material, which has been discharged to more than 90% of its charge capacity from a state where it was charged by voltage, is sufficiently... This refers to the discharged positive electrode active material. For example, in LiCoO2, the charge capacity is 21 9.2mAh / g indicates a high-voltage charging state, and from here, 90% of the charging capacity... The positive electrode active material after discharging to 197.3 mAh / g or more is a sufficiently discharged positive electrode active material. Furthermore, lithium cobalt oxide (here, impurity elements) with impurity elements of 5 at% or less. (Elements other than lithium, cobalt, and oxygen) In a 25°C environment, the battery voltage The positive electrode active material, after constant current discharge until the voltage drops below 3V (in the case of lithium counter electrode), is also sufficiently... This refers to the discharged positive electrode active material.

[0034] (Embodiment 1) [Structure of the positive electrode active material] First, using Figures 1 and 2, we will show a positive electrode active material 100, which is one embodiment of the present invention, and a conventional positive electrode active material We will explain the quality and discuss these differences. Note that the conventional correct described in this embodiment Highly active materials are those that have elements other than lithium, cobalt, and oxygen added to their interior or to their surface. This is simple lithium cobalt oxide (LiCoO2) that has not undergone any processing such as coating. be.

[0035] <Conventional positive electrode active material> A conventional example of a positive electrode active material is lithium cobalt oxide. Lithium cobalt oxide is As described in Non-Patent Documents 2 and 3, etc., the crystal structure depends on the depth of charge. The properties change. A typical crystal structure of lithium cobalt oxide is shown in Figure 2.

[0036] As shown in Figure 2, LiCoO2 at charge depth 0 (discharge state) is connected to the space group R-3m. It has regions with a crystalline structure, and there are three CoO2 layers in the unit cell. The crystal structure is sometimes called an O3-type crystal structure. The CoO2 layer refers to the cobalt layer with oxygen. This refers to a structure in which a 6-coordinate octahedron structure is continuous on a plane in a state of shared edges.

[0037] Furthermore, when the charging depth is 1, it has a crystal structure of space group P-3m1, and the unit cell contains CoO Two layers are present, but only one layer exists. Therefore, this crystal structure is sometimes called an O1 type crystal structure.

[0038] Furthermore, LiCoO2 with a charge depth of approximately 0.88 has a crystal structure with space group R-3m. This structure is similar to the structure of CoO2, such as P-3m1(O1), and R-3m(O3). It can also be described as a structure in which the LiCoO2 structure and other structures are alternately stacked. Therefore, this crystal structure This is sometimes called the H1-3 type crystal structure. However, in reality, the H1-3 type crystal structure is unique The number of cobalt atoms per lattice cell is twice that of other structures. However, as shown in Figure 2, In this specification, the c-axis of the H1-3 type crystal structure is defined as a unit for easier comparison with other structures. This will be shown as a diagram that is half the size of the original.

[0039] Repeated high-voltage charging and discharging, resulting in a charge depth of approximately 0.88 or higher. Therefore, LiCoO2 has an H1-3 type crystal structure and a R-3m(O3) structure in the discharge state. The crystal structure undergoes repeated changes in between.

[0040] However, these two crystal structures have a large displacement of the CoO2 layer. (See dotted line in Figure 2) As indicated by the arrows, in the H1-3 type crystal structure, the CoO2 layer is larger than R-3m(O3). It's collapsing. Such dynamic structural changes negatively affect the stability of the crystal structure. Shut up.

[0041] Furthermore, the volume difference is also significant. Details will be described in Example 1, but the comparison is based on the same number of cobalt atoms. In that case, the volume difference between the H1-3 type crystal structure and the O3 type crystal structure in the discharged state is 3.5% or more. be.

[0042] In addition, the H1-3 type crystal structure has continuous CoO2 layers such as P-3m1(O1) Such a structure is likely to be unstable.

[0043] 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 characteristics. This is because the breakdown of the crystal structure leads to... The number of sites where lithium can exist stably decreases, and the insertion and removal of lithium becomes more difficult. It is considered a sting.

[0044] <Positive electrode active material according to one aspect of the present invention> ≪Inside≫ In contrast, in one aspect of the present invention, the positive electrode active material 100 is in a fully discharged state and a high voltage The difference in crystal structure and volume when charged is small.

[0045] Figure 1 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 contains cobalt and oxygen. It is preferable to also contain magnesium. It is also preferable that it contains halogens such as fluorine and chlorine. It is preferable that it has at least one of the elements.

[0046] The crystal structure of the charge depth 0 (discharge state) in Figure 1 is R-3m(O3), the same as in Figure 2. In one embodiment of the present invention, the positive electrode active material 100 is fully charged to a charge depth of approximately 0.88. It has a crystal structure different from that shown in Figure 2. The crystal structure of this space group R-3m is described in this specification, etc. This will be referred to as a pseudo-spinel crystal structure. The pseudo-spinel crystal structure shown in Figure 1 is... In the structure, to explain the symmetry of the cobalt atom and the oxygen atom, lithium Although not shown, in reality, there is about 12 atomic percent lithium relative to cobalt between the CoO2 layers. Um is present. Also, in both the O3 type crystal structure and the pseudo-spinel type crystal structure, C It is preferable that a dilute amount of magnesium be present between the oO2 layers, i.e., at the lithium sites. Furthermore, it is preferable that a dilute halogen such as fluorine is present at the oxygen site. The cobalt site contains at least one of aluminum or titanium in a dilute form. preferable.

[0047] In the positive electrode active material 100, the change in crystal structure when lithium detaches is suppressed. For example, as shown by the dotted line in Figure 1, there is almost no displacement of the CoO2 layer in these crystal structures. .

[0048] Furthermore, although details will be described in Example 1, the positive electrode active material 100 has an O3 type crystal structure at a charge depth of 0. The difference in volume per unit cell of a pseudo-spinel crystal structure with a charging depth of 0.88 is 2.5 It is less than % and, more specifically, less than 2.2%.

[0049] Therefore, the crystal structure is less likely to collapse even when repeatedly charged and discharged at high voltage.

[0050] In the pseudo-spinel crystal structure, the coordinates of cobalt and oxygen in the unit cell are C, respectively. This can be shown as o(0,0,0.5) and O(0,0,x) (0.20≦x≦0.25). ru.

[0051] The dilute magnesium present between the CoO2 layers has the effect of suppressing the shifting of the CoO2 layers. Therefore, when magnesium is present between the CoO2 layers, a pseudo-spinel crystal structure is more likely to form. Therefore, it is preferable that magnesium is also distributed within the particles of the positive electrode active material 100. Furthermore, in order to distribute magnesium inside the particles, the manufacturing process of the positive electrode active material 100 is as follows: In this case, heat treatment is preferable.

[0052] However, if the heat treatment temperature is too high, cation mixing occurs and magnesium The likelihood of it entering the cobalt site increases. If magnesium is present in the cobalt site, The effect of maintaining the structure of R-3m is lost. Furthermore, if the heat treatment temperature is too high, There are concerns about adverse effects such as the reduction of cobalt to its divalent state and the evaporation of lithium. ru.

[0053] Therefore, before the heat treatment to distribute magnesium inside the particles, cobalt oxide is used. It is preferable to add halogen compounds such as fluorine compounds to the thium. Adding this causes a melting point depression of lithium cobalt oxide. By causing a melting point depression, catho At temperatures where mixing is less likely to occur, it becomes easier to distribute magnesium throughout the particles. Furthermore, if fluorine compounds are present, the corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte will be improved. Improvement can be expected.

[0054] Furthermore, a small amount of titanium and aluminum is added to the cobalt site of the positive electrode active material 100. Even if one element is absent, its presence further suppresses changes in the crystal structure.

[0055] The magnesium distributed within the positive electrode active material 100 has the effect of suppressing the shifting of the CoO2 layer. However, in order to balance the charge, the cobalt surrounding the magnesium is reduced to its divalent state. This may make it easier. Therefore, if magnesium is in excess, the positive electrode active material 100 There is a risk that some of the particles will form a structure in which MgO and CoO(II) are in solid solution. In the region where oO(II) is in a solid solution, the pathway for lithium insertion and removal is eliminated. Put it away.

[0056] However, titanium is most stable in the tetravalent state, followed by the trivalent state, while aluminum is most stable in the trivalent state. However, the divalent state is unstable. Therefore, titanium or aluminum present in cobalt sites. Therefore, even if magnesium is present at the surrounding lithium sites, it is not easily reduced to the divalent state. When titanium or aluminum is present in a dilute form at the cobalt site, MgO and CoO(I I) is unlikely to form a solid solution structure.

[0057] Furthermore, if it has at least one of titanium and aluminum, particularly in the charged state, acid The element becomes less likely to detach. In other words, oxygen bound to titanium or aluminum becomes less active. Therefore, the catalytic effect of oxidative decomposition on the electrolyte decreases, and oxidation of the electrolyte on the surface of the positive electrode active material occurs. Decomposition becomes less likely.

[0058] ≪Surface layer≫ It is preferable that magnesium is distributed throughout the particles of the positive electrode active material 100, but in addition Furthermore, it is more preferable that the magnesium concentration on the surface of the particle is higher than the average concentration of the entire particle. Since the particle surface is essentially entirely composed of crystal defects, it tends to become unstable, and changes in the crystal structure begin. This is a part that is prone to this. If the magnesium concentration in the surface layer is high, the change in crystal structure will be more effective. This can effectively suppress the reaction. Also, if the magnesium concentration in the surface layer is high, the electrolyte will decompose. It can also be expected that the corrosion resistance to hydrofluoric acid produced will improve.

[0059] Furthermore, it is preferable that the concentration of fluorine in the surface layer of the positive electrode active material 100 is higher than the average concentration of the entire particle. It is so. The presence of fluorine in the surface layer, which is the region in contact with the electrolyte, provides resistance to hydrofluoric acid. It can effectively improve feeding habits.

[0060] Furthermore, the concentration of either titanium or aluminum is higher on the surface than the average concentration of the entire particle. A high concentration in the region is preferable. In the region with a high magnesium concentration, titanium or aluminum If one of the elements present in large quantities, it will strongly exert an effect of suppressing changes in the CoO2 layer. This also makes oxidative decomposition of the electrolyte on the surface of the positive electrode active material less likely to occur.

[0061] Thus, the surface layer of the positive electrode active material 100 is more magnesium, fluorine, titanium, and Preferably, the composition of the interior is different from that of the interior, with a high concentration of at least one element of aluminum. Furthermore, it is preferable that the composition adopts a crystalline structure that is stable at room temperature. Therefore, the surface layer is the interior It may have a different crystal structure from the surface portion. For example, at least the surface portion of the positive electrode active material 100 Some parts may have a rock salt-type crystalline structure. Furthermore, the surface and interior may have different crystalline structures. If this is present, it is preferable that the orientation of the crystals in the surface layer and the interior are roughly the same.

[0062] Furthermore, if the positive electrode active material 100 contains magnesium and titanium, the titanium concentration P It is preferable that the tetravalent ion is located in a region deeper than the magnesium concentration peak. Since titanium can be trivalent, the distance between titanium and oxygen can change depending on the valency of titanium. Therefore, the area around titanium atoms tends to be stable even if there are variations in the distance between metal and oxygen atoms. For example, if the surface layer of the positive electrode active material 100 has a rock salt type crystal structure, the region containing titanium This region can function as a buffer area and contribute to stabilizing the internal crystal structure.

[0063] However, if the surface layer consists only of MgO, or only of a solid solution of MgO and CoO(II), then As mentioned above, the pathway for lithium insertion and removal is eliminated. Therefore, the surface layer 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.

[0064] ≪Grain boundary≫ The positive electrode active material 100 contains magnesium, halogen, cobalt, aluminum, or titanium. The particles may be present randomly and dilutely within the grain, but some are segregated at the grain boundaries. This is preferable.

[0065] In other words, the magnesium concentration at and near the grain boundaries of the positive electrode active material 100 is... It is preferable that the fluorine concentration is higher than in other regions. This is preferable. Also, either titanium or aluminum at the grain boundary and its vicinity. A high concentration of [the substance] is also preferable.

[0066] Similar to particle surfaces, grain boundaries are also surface defects. Therefore, they are prone to instability and changes in crystal structure. This process is likely to begin. Therefore, if the magnesium concentration at and near the grain boundaries is high, Changes in the crystal structure can be suppressed more effectively. Also, the grain boundaries and their vicinity If the concentration of either tung or aluminum is high, it has the effect of suppressing changes in the CoO2 layer. It can exert a strong effect.

[0067] Furthermore, if the magnesium and fluorine concentrations at and near the grain boundaries are high, the positive electrode active material Even if cracks occur along the grain boundaries of 100 particles, the surface created by the cracks Magnesium and fluorine concentrations increase in the vicinity of the crack. Therefore, the positive electrode after cracking occurs The active material can also be made more resistant to hydrofluoric acid corrosion.

[0068] In this specification, the vicinity of a grain boundary refers to the region extending approximately 10 nm from the grain boundary. Let's do it this way.

[0069] ≪Particle size≫ The particle size of the positive electrode active material 100 is important; if it is too large, lithium diffusion becomes difficult, and it is coated onto the current collector. When this happens, there are problems such as the surface of the active material layer becoming too rough. On the other hand, if it is too small, current collection... Problems include difficulty in supporting the active material layer during coating onto the body, and excessive reaction with the electrolyte. This occurs. Therefore, a median diameter (D50) of 1 μm to 100 μm is preferable. More preferably, the particle size is between 2 μm and 40 μm.

[0070] <Analysis method> A positive electrode according to one aspect of the present invention, in which a certain material exhibits a pseudo-spinel crystal structure when charged at a high voltage. Whether or not it is active material 100 is determined by XRD, electron diffraction, and neutron diffraction on a positive electrode charged with high voltage. By analyzing using methods such as linear diffraction, electron spin resonance (ESR), and nuclear magnetic resonance (NMR), it can be determined. It can be determined. In particular, XRD can analyze the crystal structure of the positive electrode active material with high resolution, Analysis of lattice periodic strain and crystallite size allows for comparison of height and crystal orientation. It is possible to measure the positive electrode obtained by disassembling a secondary battery and obtain sufficient accuracy, etc. It is preferable in that respect.

[0071] The positive electrode active material 100 in one aspect of the present invention, as described above, is in a high-voltage charging state and a discharge state A characteristic feature is that there is little change in the crystal structure in the high-voltage charging state compared to the discharge state. Materials with large crystal structures making up more than 50% are undesirable because they cannot withstand high-voltage charging and discharging. No. And as will be explained in detail in Example 1, simply adding elements does not result in the desired crystal structure. It is important to note that there are cases where it is not taken. For example, when magnesium and fluorine are present. Even though they share the common characteristic of being lithium cobaltate, the pseudo-spinel crystal structure is less than 60 wt%. There are cases where it is on top, and cases where the H1-3 type crystal structure accounts for 50% or more. Also, predetermined At this voltage, the pseudo-spinel crystal structure becomes almost 100%, and if the predetermined voltage is further increased... In some cases, an H1-3 type crystal structure may be formed. Therefore, the positive electrode active material 10 in one aspect of the present invention To determine whether the value is 0 or not, analysis of the crystal structure, including XRD, is necessary. be.

[0072] ≪Charging method≫ High-voltage charging for making the above determination is, for example, a coin cell (CR2032) with a lithium counter electrode. This can be done by creating a pipe (20mm in diameter and 3.2mm in height).

[0073] More specifically, the positive electrode contains a positive electrode active material, acetylene black (AB), and polyfluoride. Vinylidene (PVDF) is mixed with the positive electrode active material in a ratio of AB:PVDF = 95:3:2 (by weight). A slurry can be used that has been coated onto an aluminum foil positive electrode current collector.

[0074] 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 happens, the potential of the secondary battery and the potential of the positive electrode are different. For example, when we focus on the potential of the positive electrode, 4.5V charging with a graphite counter electrode is roughly equivalent to 4.6V charging with a lithium counter electrode. In this specification, voltages and potentials refer to the potential of the positive electrode unless otherwise specified.

[0075] The electrolyte in the electrolyte solution is 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). C:DEC = 3:7 (volume ratio), with vinylene carbonate (VC) mixed in at 2 wt%. It is possible to use things.

[0076] Polypropylene with a thickness of 25 μm can be used for the separator.

[0077] The positive electrode and negative electrode cans can be made of stainless steel (SUS). ru.

[0078] 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. Note that 1C is defined as 137mA / g. Temperature The temperature is set to 25°C. After charging in this way, the coin cell is disassembled and the positive electrode is removed. This allows us to obtain a positive electrode active material that has been charged with high voltage. When performing various analyses afterward, the extracted positive electrode To suppress reactions with external components, it is preferable to seal the active material in an argon atmosphere. For example, XRD can be performed by sealing the sample in a sealed container under an argon atmosphere.

[0079] ≪XRD≫ Based on the pseudo-spinel crystal structure and the H1-3 type crystal structure model, the CuKα1 line is calculated. Figure 3 shows the ideal powder XRD pattern. For comparison, LiCoO2 with a charge depth of 0 is also shown. An ideal XRD calculated from the crystal structures of 2(O3) and CoO2(O1) at a charge depth of 1. The patterns are 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 pattern of the H1-3 type crystal structure is the crystal structure information described in Non-Patent Document 4. Created similarly from the report. The pseudo-spinel pattern is the XRD pattern of the positive electrode active material in one aspect of the present invention. From the turn, Rietveld analysis software, TOPAS by Bruker AXS. In version 3, the crystal structure was estimated, and an XRD pattern was created, similar to the others. The XRD pattern of a positive electrode active material according to one embodiment of the present invention is shown in Example 1.

[0080] As shown in Figure 3, in the pseudo-spinel crystal structure, 2θ = 19.30 ± 0.20° (19. (10° to 19.50°), and 2θ = 45.55 ± 0.10° (45.45° or less) Diffraction peaks appear above 45.65°. More specifically, 2θ = 19.30 ±0.10° (between 19.20° and 19.40°), and 2θ = 45.55 ± 0.0 A sharp diffraction peak appears at 5° (between 45.50° and 45.60°). However, H1- In the type 3 crystal structure and CoO2 (P-3m1, O1), peaks do not appear at these positions. Therefore, when charged at high voltage, 2θ = 19.30 ± 0.20°, and 2θ = The appearance of a peak at 45.55±0.10° indicates that the positive electrode active material 100 of one embodiment of the present invention This can be considered a characteristic of [the product / service].

[0081] Furthermore, in one embodiment of the present invention, the positive electrode active material 100, when charged with high voltage, exhibits a pseudo-spinel type crystal structure. Although it has a structure, not all particles have to have a pseudo-spinel type crystal structure. It may contain some amorphous material, or part of it may be amorphous. However, regarding the XRD pattern, When performing vertex analysis, it is preferable that the pseudo-spinel crystal structure accounts for 50 wt% or more. It is more preferable that it be 60 wt% or more, and even more preferable that it be 66 wt% or more. It is desirable that the pseudo-spinel crystal structure be 50 wt% or more, more preferably 60 wt% or more, Preferably, if the amount is 66 wt% or more, it will be a positive electrode active material with sufficiently excellent cycle characteristics. It is possible.

[0082] Furthermore, the crystallite size of the pseudo-spinel structure possessed by the particles of the positive electrode active material is the same as that of LiCo in the discharged state. It only drops to about 1 / 10th of O2(O3). Therefore, it has the same XR as the positive electrode before charging and discharging. Even under the measurement conditions of D, a peak of a clear pseudo-spinel crystal structure can be confirmed after high-voltage charging. On the other hand, in simple LiCoO2, even if a part has a structure similar to the pseudo-spinel crystal structure, the crystallite size becomes small, and the peak becomes broad and small. The crystallite size can be obtained from the half-value width of the XRD peak.

[0083] Note that the characteristics revealed from the XRD pattern are the characteristics of the internal structure of the positive electrode active material. For a positive electrode active material with a particle size (D50) of about 1 μm to 100 μm, since the volume of the surface layer part is very small compared to the inside, even if the surface layer part of the positive electrode active material 100 has a crystal structure different from the inside, it is highly likely not to appear in the XRD pattern.

[0084] ≪ESR≫ In the positive electrode active material 100 having a pseudo-spinel crystal structure, as shown in FIGS. 1 and 4(A), cobalt exists at the site of six-fold coordination with oxygen. As shown in FIG. 4(B), for cobalt with six-fold coordination with oxygen, the 3d orbitals are split into e orbitals and t g orbitals, and the energy of the t 2g orbital placed avoiding the direction where oxygen exists is low. A part of the cobalt existing at the six-fold oxygen coordination site is the diamagnetic Co 2g cobalt in which all the t orbitals are filled. However, another part of the cobalt existing at the six-fold oxygen coordination site 2g may be paramagnetic Co 3+ or Co 2+ 4+ cobalt. This paramagnetic cobalt cannot be distinguished by ESR because both Co 4+ and Co 2+ 2+ 4+ have one unpaired electron, but it can take either valence depending on the valence of the elements present around it. [[ID=XXX]]

[0085] On the other hand, in conventional positive electrode active materials, the surface layer of the charged material contains spinel that does not contain lithium. Some sources state that it may have a crystal structure of the type shown in Figure 5(A). This will result in a Co3O4 crystal structure, which is a Nell-type crystal structure.

[0086] When spinel is represented by the general formula A[B2]O4, element A is oxygen in 4-coordinate state, and element B is oxygen in 6-coordinate state. This results in coordination. Therefore, in this specification, sites with 4 oxygen coordination are referred to as sites A, and sites with 6 oxygen coordination are referred to as sites A. Site B is sometimes referred to as Site T.

[0087] In Co3O4 with a spinel-type crystal structure, not only the B site with 6 oxygen coordinates, but also the 4 oxygen coordinates... Cobalt is also present at site A. As shown in Figure 5(B), in oxygen 4-coordinate cobalt Split e g orbit and t 2g Of the orbits, e g The orbital energy is low. Therefore, oxygen is supplied in four parts. Co 2+ Co 3+ and Co 4+ All of them have unpaired electrons and are paramagnetic. If particles containing sufficient spinel-type Co3O4 are analyzed by ESR, etc., then Co3O4 will be found to be oxygen-4 coordinated. 2+ Co 3+ or Co 4+ A peak originating from paramagnetic cobalt should be detected. ru.

[0088] However, in one embodiment of the present invention, the positive electrode active material 100 is made of oxygen-4 coordinated paramagnetic cobalt. The resulting peak is so small that it cannot be detected. In other words, compared to the conventional example, the positive of one aspect of the present invention The most active material is one in which the peak originating from spinel-type Co3O4, which can be detected by ESR, is small. In some cases, the amount is so small that it cannot be detected. Spinel-type Co3O4 does not contribute to the charge-discharge reaction, Because it is thermally unstable, it is preferable to have less spinel-type Co3O4. Therefore, the positive electrode active material 100 can be said to be different from conventional examples.

[0089] ≪XPS≫ X-ray photoelectron spectroscopy (XPS) can analyze depths of approximately 2 to 8 nm (usually around 5 nm) from the surface. Because analysis of the region is possible, the concentration of each element can be quantified in approximately half of the surface region. It can be analyzed precisely. Furthermore, narrow-scan analysis can analyze the bonding state of elements. This is possible. Note that the quantitative accuracy of XPS is often around ±1 atomic percent, and the detection limit is limited to the element. It varies, but it is approximately 1 atomic percent.

[0090] When XPS analysis was performed on positive electrode active material 100, the concentration of cobalt was set to 1, The relative concentration of magnesium is preferably between 0.4 and 1.5, and between 0.45 and 1.00. A full concentration is preferable. Furthermore, a relative fluorine concentration of 0.05 to 1.5 is preferable, and 0. A concentration of 3 or more and 1.00 or less is more preferable. Also, the concentration of either titanium or aluminum. The relative value is preferably 0.05 or more and 0.4 or less, and more preferably 0.1 or more and 0.3 or less.

[0091] Furthermore, when the positive electrode active material 100 was analyzed using XPS, the bond energy between fluorine and other elements was determined. The peak showing - is preferably 682eV or higher and less than 685eV, and 684.3eV It is even more preferable that it be of a certain degree. This is because the binding energy of LiF is 685 eV. And it is a value different from both of the bond energy values ​​of magnesium fluoride, which is 686 eV. In other words, if the positive electrode active material 100 contains fluorine, lithium fluoride and magnesium fluoride It is preferable that the bond is not made of sium.

[0092] Furthermore, when XPS analysis was performed on the positive electrode active material 100, the bonding between magnesium and other elements was observed. The peak indicating energy is preferably between 1302 eV and less than 1304 eV. It is even more preferable that the energy is around 1303 eV. This is because the binding energy of magnesium fluoride This value is different from the energy of 1305 eV and is closer to the bond energy of MgO. In other words, if the positive electrode active material 100 contains magnesium, then bonds other than magnesium fluoride It is preferable that this be the case.

[0093] ≪EDX≫ EDX measurement is a method of measuring while scanning within a region and evaluating that region in two dimensions. This is sometimes called X-plane analysis. Furthermore, data from linear regions is extracted from EDX plane analysis, and the original The process of evaluating the distribution of particle concentration within the positive electrode active material particles is sometimes called linear analysis.

[0094] EDX surface analysis (e.g., elemental mapping) can be used to analyze the interior, surface, and vicinity of grain boundaries. Quantitative analysis of the concentrations of magnesium, fluorine, titanium, or aluminum. It is possible to detect magnesium, fluorine, titanium, or aluminum through EDX radiation analysis. It is possible to analyze the peak concentration of the substance.

[0095] When EDX radiation analysis was performed on positive electrode active material 100, the magnesium concentration peak in the surface layer was observed. It is preferable that it exists within a depth of 3 nm from the surface toward the center of the positive electrode active material 100. It is more preferable that it exists up to a depth of 1 nm, and more preferably up to a depth of 0.5 nm. That is even more preferable.

[0096] Furthermore, it is preferable that the distribution of fluorine in the positive electrode active material 100 overlaps with the distribution of magnesium. Therefore, when EDX radiation analysis was performed, the peak in fluorine concentration at the surface was in the positive electrode active material. Preferably, it exists from the surface towards the center to a depth of 3 nm, and to a depth of 1 nm It is more preferable that it be present up to a certain depth, and even more preferable that it be present up to a depth of 0.5 nm. stomach.

[0097] Furthermore, when EDX radiation analysis was performed, the amount of titanium or aluminum in the surface layer of the positive electrode active material 100 was found to be small. At least one concentration peak is located at a depth of 0.2n from the surface to the center of the positive electrode active material 100. It is preferable that it exists at a depth of 0.5 nm to 3 nm, with a minimum wavelength of m or less. It is preferable to do so.

[0098] Furthermore, when line analysis or surface analysis was performed on the positive electrode active material 100, the grain boundaries near the crystal grain boundaries were observed. 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.

[0099] [Method for preparing positive electrode active material] Next, an example of a method for producing a positive electrode active material 100, which is one aspect of the present invention, will be described.

[0100] <Step S11: Preparation of starting materials> First, prepare a lithium source and a cobalt source as starting materials. Also, a magnesium source. It is also preferable to prepare a fluorine source as a starting material.

[0101] For example, lithium carbonate and lithium fluoride can be used as lithium sources. As the ruthenium source, for example, cobalt oxide can be used. As the magnesium source, for example, magnesium oxide, magnesium fluoride, magnesium hydroxide, magnesium carbonate etc. can be used. As the fluorine source, for example, lithium fluoride, magnesium fluoride etc. can be used. That is, lithium fluoride can be used as both a lithium source and a fluorine source.

[0102] The atomic weight of magnesium contained in the magnesium source is preferably 0 .001 or more and 0.1 or less, more preferably 0.005 or more and 0.02 or less, and even more preferably about 0.01 when the atomic weight of cobalt is taken as 1.

[0103] The fluorine contained in the fluorine source is preferably 1.0 times or more and 4 times or less (atomic ratio) of the magnesium contained in the magnesium source, and more preferably 1.5 times or more and 3 times or less (atomic ratio).

[0104] <Step S12: Mixing of starting materials> Next, the above starting materials are mixed. For mixing, for example, a ball mill, a bead mill, etc. can be used. When using a ball mill, for example, it is preferable to use zirconia balls as the media.

[0105] <Step S13: First heat treatment> Next, the material mixed in Step S12 is heated. This step may be referred to as firing or the first heat treatment. The heating is preferably performed at 800 °C or more and less than 1100 °C, more preferably at 900 °C or more and 1000 °C or less, and even more preferably about 950 °C. If the temperature is too low, there is a risk that the decomposition and melting of the starting materials will be insufficient. On the other hand, if the temperature is too high, there is a risk that the starting materials will be over-decomposed or over-melted. If it is too high, defects may occur where Co becomes divalent due to reduction of Co and evaporation of Li. There is a risk of occurrence.

[0106] The heating time is preferably 2 hours or more and 20 hours or less. The firing is preferably carried out in an atmosphere such as dry air. For example, heating is carried out at 1000 °C for 10 hours, and the temperature increase is preferably 20 0 °C / h, and the flow rate of the dry atmosphere is preferably 10 L / min. Then, the heated material is cooled to room temperature. For example, the temperature decrease time from the holding temperature to room temperature is preferably 10 hours or more and 50 hours or less.

[0107] By heating in step S13, lithium cobaltate can be synthesized. When the starting material contains magnesium and fluorine, magnesium and fluorine become particles of a composite oxide distributed in lithium cobaltate.

[0108] Also, particles of a composite oxide containing lithium, cobalt, fluorine, and magnesium synthesized in advance as a starting material may be used. In this case, steps S12 and step S1 3 can be omitted. For example, lithium cobaltate particles (trade name: C-20F) manufactured by Nippon Chemical Industry Co., Ltd. can be used as one of the starting materials. These have a particle size of about 20 μm and are lithium cobaltate particles containing fluorine, magnesium, calcium , sodium, silicon, sulfur, and phosphorus in a region analyzable by XPS from the surface.

[0109] <Step S14: Coating with a material containing at least one of titanium or aluminum> Next, the surface of the lithium cobaltate particles is coated with at least one of titanium or aluminum. It is preferable to coat with a material that possesses the following properties. Methods of coating include the sol-gel method, among others. Liquid phase method, solid phase method, sputtering method, vapor deposition method, CVD (chemical vapor deposition), PLD (powder deposition) Methods such as the laser deposition method can be applied. In this embodiment, uniform This section describes the application of the sol-gel method, which is expected to provide good coating and can be processed at atmospheric pressure.

[0110] First, titanium alkoxide, or aluminum alkoxide, or a mixture thereof It is dissolved in alcohol, and then lithium cobalt oxide particles are mixed in.

[0111] Examples of titanium alkoxides include Titanium tetraisopropox ide(TTIP) can be used. For example, aluminum alkoxides can be used. Aluminum isopropoxide can be used as the solvent alcohol. For example, isopropanol can be used.

[0112] The required amount of metal alkoxide varies depending on the particle size of lithium cobalt oxide. For example, TT When using IP, if the particle size (D50) of lithium cobalt oxide is about 20 μm, then cobalt For lithium trioxide particles, the TTIP is 0.004 ml / g or more and 0.01 ml / g or less. It is preferable to add it in such a way that the particle size is the same when using aluminum isopropoxide. Therefore, aluminum isopropoxide is added to lithium cobalt oxide particles at a concentration of 0.027 It is preferable to add it in an amount of 9 g / g or more and 0.0697 g / g or less.

[0113] Next, a mixture of an alcoholic solution of a metal alkoxide and lithium cobalt oxide particles is vaporized. Stir in an atmosphere containing air. Stirring can be carried out, for example, with a magnetic stirrer. The stirring time should be sufficient for the water and metal alkoxide in the atmosphere to undergo hydrolysis and polycondensation reactions. For example, it can be carried out under the conditions of 4 hours, 25 °C, and 90% RH (Relative Humidity, relative humidity). By reacting the water vapor in the atmosphere with the metal alkoxide, the sol-gel reaction can proceed more slowly than when adding liquid water. Also, by reacting the metal alkoxide with water at room temperature, the sol-gel reaction can proceed more slowly than when heating at a temperature exceeding the boiling point of the alcohol solvent, for example. By proceeding with the sol-gel reaction slowly, a coating layer with uniform thickness and good quality can be formed. Recover the precipitate from the mixed solution after the above treatment. As the recovery method, filtration, centrifugation, evaporation to dryness, etc. can be applied. The precipitate can be washed with the same alcohol as the solvent in which the metal alkoxide was dissolved.

[0114] Next, dry the recovered residue. For example, it can be dried in a vacuum or by ventilation drying at 70 °C for 1 hour or more and 4 hours or less. <Step S15: Second heat treatment> Next, heat the lithium cobaltate particles coated with the material having titanium or aluminum prepared in Step S14. This step may be referred to as the second heat treatment. The heating time is preferably such that the holding time at the holding temperature is 1 hour or more and 50 hours or less, and 2

[0115]

[0116]

[0117]

[0118] ​​​​​​​​​​​A heating time of more than 20 hours is more preferable. If the heating time is too short, magnesium and fluorine will be affected. If this is added, there is a risk that segregation to the surface layer and near the grain boundaries will be insufficient. However, if the heating time is too long, these golds, if coated with titanium or aluminum, Excessive diffusion of the compound may lead to low concentrations in the surface layer and near grain boundaries.

[0119] The preferred holding temperature is 500°C to 1200°C, and 700°C to 920°C. More preferably, a temperature of 800°C to 900°C is preferable. If the holding temperature is too low, the magnet There is a risk that segregation of nesium will not occur. However, if the level is too high, Mg will also be distributed to the Co site. Co 3+ Instead, a CoO like Co 2+ It becomes stable This could lead to problems such as the inability to maintain the layered structure of CoO2.

[0120] Furthermore, the second heat treatment is preferably carried out in an oxygen-containing atmosphere. If the oxygen partial pressure is low, If the heating temperature is not lowered further, there is a risk of Co being reduced.

[0121] In this embodiment, the holding temperature is set to 800°C and held for 2 hours, with the temperature increase being 200°C. The oxygen flow rate is set to 10 L / min per hour.

[0122] When cooling after heating, it is preferable to allow a longer cooling time, as this makes it easier to stabilize the crystal structure. For example... It is preferable that the cooling time from the holding temperature to room temperature be between 10 and 50 hours.

[0123] Thus, the first heat treatment (step S13) and the second heat treatment (step S15) It is preferable to perform heating multiple times as described above. In the first heating treatment, the starting materials should be thoroughly heated together. To facilitate the reaction, the melting points of Co3O4 (895°C) and Li2CO3 (723°C) are required. Heat to a higher temperature. In the next heat treatment, magnesium is distributed between the CoO2 layers. To achieve this, heat at a lower temperature than the first heat treatment. Specifically, Co 3+ Co 2+ Yo The temperature at which it becomes stable is 920°C in air, according to the Ellingham diagram, therefore the second heating treatment The process is preferably carried out at a temperature of 920°C or lower.

[0124] <Step S16: Recovery> Next, the cooled particles are collected. Furthermore, it is preferable to sift the particles. In this process, a positive electrode active material 100 according to one embodiment of the present invention can be produced.

[0125] Furthermore, after step S16, the steps from step S14 to step S16 are repeated multiple times. The coating may be performed using the sol-gel method. The number of repetitions may be one or two or more. By repeatedly performing sol-gel treatment and heat treatment, cracks are formed in the lithium cobalt oxide particles. If cracks have occurred, they can be reduced.

[0126] Furthermore, the type of metal alkoxide used when performing sol-gel treatment multiple times may differ from the same type. Yes, it's fine, and it's also fine if they're different. If you use different materials, for example, in the first sol-gel treatment. Titanium alkoxide was used in the first step, and aluminum alkoxide was used in the second sol-gel treatment. It is possible.

[0127] In this embodiment, the positive electrode active material 100 includes lithium, cobalt, and oxygen. Although the materials have been described, the present invention is not limited thereto. For example, positive electrode active material 100 The transition metals it contains are not limited to cobalt, but also very small amounts of nickel and manganese. It may contain at least one of the above transition metals. In addition, in addition to the above transition metals, the starting material may contain a very small amount. Aluminum may also be added.

[0128] In another aspect of the present invention, a sufficiently charged positive electrode active material and a sufficiently discharged positive electrode active material Therefore, it is sufficient if the change in crystal structure is suppressed. For this reason, the pseudo-spirometry defined in this specification It does not have to take on a Nell-type crystal structure, and magnesium, fluorine, titanium or aluminum It does not need to contain elements such as 'mu'.

[0129] Furthermore, the positive electrode active material 100 consists of carbon, sulfur, silicon, sodium, calcium, and zirconium. It may also contain other elements such as the following.

[0130] This embodiment can be used in appropriate combination with other embodiments.

[0131] (Embodiment 2) In this embodiment, it is used in a secondary battery having the positive electrode active material 100 described in the previous embodiment. Examples of materials that can be used will be described. In this embodiment, the positive electrode, negative electrode and electrolyte However, let's take a secondary battery, which is enclosed in an outer casing, as an example to explain.

[0132] [Positive electrode] The positive electrode comprises a positive electrode active material layer and a positive electrode current collector.

[0133] <Cathode active material layer> The positive electrode active material layer contains at least positive electrode active material. Furthermore, the positive electrode active material layer contains positive electrode active material In addition, other substances such as a coating on the surface of the active material, a conductive additive, or a binder may be included.

[0134] As the positive electrode active material, the positive electrode active material 100 described in the previous embodiment can be used. By using the positive electrode active material 100 described in the previous embodiment, high capacity and cycle characteristics can be achieved. It can be used to create an excellent rechargeable battery.

[0135] As conductive additives, carbon materials, metal materials, or conductive ceramic materials can be used. Yes, it is possible. Additionally, fibrous materials may be used as conductive additives. The conductivity relative to the total amount of the active material layer... The content of the electrolytic agent is preferably 1 wt% to 10 wt%, and preferably 1 wt% to 5 wt%. This is preferable.

[0136] Conductive additives can be used to form an electrical conduction network within the active material layer. The agent can maintain the electrical conduction pathway between the positive electrode active materials. By adding an electro-enhancing agent, it is possible to create an active material layer with high electrical conductivity. .

[0137] Examples of conductive additives include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fibers. Fibers can be used. For example, mesophase pitch carbon fibers can be used. Carbon fibers such as isotropic pitch carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tubes can be fabricated, for example, by vapor phase growth. Also, as a conductive additive, for example... Examples include carbon black (acetylene black (AB), etc.) and graphite particles. Carbon materials such as graphene and fullerene can be used. Also, for example, copper, nickel Metal powders such as oxal, aluminum, silver, and gold, as well as metal fibers and conductive ceramic materials. It can be used.

[0138] Furthermore, graphene compounds may be used as conductive additives.

[0139] Graphene compounds possess excellent electrical properties, including high conductivity, as well as high flexibility and high It possesses excellent physical properties, such as high mechanical strength, and may also have other properties. The compound has a planar shape. Graphene compounds enable surface contact with low contact resistance. Furthermore, even thin materials can have very high conductivity, allowing for efficient conduction within the active material layer with only a small amount. An electric current can be formed. Therefore, graphene compounds can be used as conductive additives. This is preferable because it increases the contact area between the active material and the conductive additive. By using a laser dryer, the entire surface of the active material is covered and converted into graphene, which is a conductive additive. It is preferable to form the composite as a coating. Furthermore, it may be possible to reduce electrical resistance. Therefore, it is preferable. Here, as graphene compounds, for example, graphene, multigraphene, Alternatively, it is particularly preferable to use RGO. Here, RGO is, for example, graphene oxide (g This refers to the compound obtained by reducing raphene oxide (GO).

[0140] When using active materials with small particle sizes, for example, active materials with a particle size of 1 μm or less, the specific surface area of ​​the active material is Larger materials require more conductive paths to connect the active materials. Therefore, a larger amount of conductive additive is needed. This tends to happen, and relatively, the amount of active material carried decreases. When this decreases, the capacity of the secondary battery decreases. In such cases, a conductive additive is used. When graphene compounds are used, even small amounts of graphene compounds efficiently form conductive paths. This is particularly preferable because it does not require reducing the amount of active material supported.

[0141] In the following example, a graphene compound is used as a conductive additive in the active material layer 200. An example of the cross-sectional configuration will be explained.

[0142] Figure 6(A) shows a longitudinal cross-sectional view of the active material layer 200. The active material layer 200 consists of granular positive electrode active material. It contains 100, a graphene compound 201 as a conductive additive, and a binder (not shown). Here, graphene compound 201 may be, for example, graphene or multigraphene. It is sufficient if it is present. Here, it is preferable that the graphene compound 201 has a sheet-like shape. Furthermore, graphene compound 201 is a multigraphene, or / or multiple graphenes. The graphene may be partially overlapping and form a sheet.

[0143] In the longitudinal section of the active material layer 200, as shown in Figure 6(B), the interior of the active material layer 200 In the diagram, the graphene compound 201 is dispersed in a generally uniform sheet-like manner. (Figure 6(B)) Here, graphene compound 201 is schematically represented by a thick line, but in reality, it is a single layer of carbon molecules or It is a thin film with multiple layers of thickness. Multiple graphene compounds 201 are arranged in multiple granular cathodes. The active material 100 is partially covered, or attached to the surface of multiple granular positive electrode active materials 100. Because they are formed to fit together, they are in surface contact with each other.

[0144] Here, multiple graphene compounds bond together to form a network of graphene compounds. Forming a sheet (hereinafter referred to as graphene compound net or graphene net) Yes, it is possible. When the active material is covered with a graphene net, the graphene net connects the active materials to each other. It can also function as a binder. Therefore, it reduces the amount of binder needed. Because it is possible to do so or not to use it, the ratio of active material to electrode volume or electrode weight The efficiency can be improved. In other words, the capacity of the secondary battery can be increased.

[0145] Here, graphene oxide is used as graphene compound 201 and mixed with the active material to form the active material It is preferable to reduce the layer after forming the layer that will become layer 200. By using graphene oxide, which has extremely high dispersibility in polar solvents, graphene formation can be achieved. The compound 201 can be dispersed approximately uniformly within the active material layer 200. The solvent is volatilized and removed from the dispersion medium containing dispersed graphene oxide, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps, and By being dispersed to the extent that they are in surface contact, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be carried out, for example, by heat treatment or by using a reducing agent. That's fine.

[0146] Therefore, unlike granular conductive additives such as acetylene black that make point contact with the active material, graph Compound 201 enables surface contact with low contact resistance, unlike conventional conductive additives. It improves the electrical conductivity between the granular positive electrode active material 100 and the graphene compound 201 using only a small amount. Therefore, the ratio of positive electrode active material 100 in the active material layer 200 can be increased. This allows for an increase in the discharge capacity of the secondary battery.

[0147] Furthermore, by using a spray drying device beforehand, the entire surface of the active material is covered with a conductive additive. A graphene compound is formed as a coating, and then the graphene compound is used to guide the active materials together. It can also be used to create an electric pass.

[0148] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isoprene rubber. N-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer. Fluororubber can be used.

[0149] Furthermore, it is preferable to use a water-soluble polymer as the binder. For example, polysaccharides can be used as the derivative. Cellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose Cellulose derivatives such as lurose, diacetylcellulose, and regenerated cellulose, as well as starch, etc. These can be used. Furthermore, these water-soluble polymers can be used in combination with the aforementioned rubber materials. It would be even better if they were there.

[0150] Alternatively, as a binder, polystyrene, polymethyl acrylate, polymethyl methacrylate can be used. Chill (polymethyl methacrylate (PMMA)), sodium polyacrylate, polyvinyl Polyalcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, Polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene Polyethylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer It is preferable to use materials such as polyvinyl acetate and nitrocellulose.

[0151] You may use a combination of several of the binders mentioned above.

[0152] For example, a material with particularly excellent viscosity-modifying properties may be used in combination with other materials. For example, rubber materials have excellent adhesive and elastic properties, but their viscosity is difficult to adjust when mixed with a solvent. In such cases, for example, mixing with a material that has particularly excellent viscosity-modifying effects may be used. This is preferable. As a material with particularly excellent viscosity adjustment effect, for example, a water-soluble polymer can be used. Furthermore, water-soluble polymers that are particularly excellent in viscosity adjustment include the aforementioned polysaccharides, for example, calcium carbonate. Voxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxy Cellulose derivatives such as propylcellulose, diacetylcellulose, and regenerated cellulose. Body or starch can be used.

[0153] Furthermore, cellulose derivatives such as carboxymethylcellulose are, for example, carboxymethyl By using salts such as sodium salts or ammonium salts of cellulose, the solubility increases. It becomes easier to exert its effect as a viscosity modifier. The increased solubility makes the electrode slurry - When manufacturing, it is also possible to improve the dispersibility with the active material and other components. As for cellulose and cellulose derivatives used as electrode binders, This shall also include salt.

[0154] Water-soluble polymers stabilize viscosity by dissolving in water, and also function as active materials and binders. Other materials to be combined with it, such as styrene-butadiene rubber, are stably separated in an aqueous solution. It can be dispersed. Furthermore, because it has functional groups, it is easily and stably adsorbed onto the surface of the active material. This is expected. Also, cellulose derivatives such as carboxymethylcellulose, For example, many materials have functional groups such as hydroxyl groups and carboxyl groups, and because they have functional groups It is expected that the polymers will interact with each other and exist to broadly cover the surface of the active material.

[0155] When a binder covering or in contact with the surface of the active material forms a film, it is considered a passivation film. It is also expected to play a role in suppressing the decomposition of the electrolyte. Here, the passive film is an electrolytic film. A film that does not conduct air, or a film with extremely low electrical conductivity, for example, a film that is immobile on the surface of an active material. When a film is formed, the decomposition of the electrolyte can be suppressed at the battery reaction potential. Furthermore, the passivation film suppresses electrical conductivity while allowing lithium ions to conduct. Even better.

[0156] <Positive electrode current collector> As the positive electrode current collector, metals such as stainless steel, gold, platinum, aluminum, and titanium, and this Highly conductive materials such as alloys can be used. Also, the material used for the positive electrode current collector is It is preferable that the material does not dissolve at the positive electrode potential. Also, silicon, titanium, neodymium, and scan are preferred. Using aluminum alloys to which elements that improve heat resistance, such as zinc and molybdenum, are added. It can also be formed with a metallic element that reacts with silicon to form a silicide. Good. Metal elements that react with silicon to form silicides include zirconium and titanium. Hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, Examples include cobalt and nickel. Current collectors come in foil, plate (sheet), mesh, and perforated forms. Shapes such as barrel-shaped or expanded metal-shaped can be used as appropriate. The current collector has a thickness of 5 It is best to use materials with a size between 30 μm and 40 μm.

[0157] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer also contains a conductive additive and It may have a binder.

[0158] <Negative electrode active material> For example, alloy materials or carbon-based materials can be used as the negative electrode active material.

[0159] As a negative electrode active material, it is possible to perform charge and discharge reactions through alloying and dealloying reactions with lithium. Any suitable element can be used. For example, silicon, tin, gallium, aluminum, galvanic acid. Among the following, a small amount is found in luminum, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one element can be used. Such elements have a larger capacity compared to carbon. In particular, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, silicon is used as the negative electrode active material. It is preferable to use lycon. Alternatively, compounds containing these elements may be used. Example For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V 2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3 Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, I Examples include nSb and SbSn. Here, the charge-discharge reaction occurs through alloying and dealloying reactions with lithium. Elements capable of performing this action, and compounds containing such elements, are sometimes referred to as alloying materials. ru.

[0160] In this specification, SiO refers to silicon monoxide, for example. Alternatively, SiO refers to SiO xIt can also be expressed as follows. Here, it is preferable that x has one neighboring value. For example, x is 0 A value of 0.2 to 1.5 is preferred, and a value of 0.3 to 1.2 is more preferred.

[0161] Carbon-based materials include graphite, easily graphitizable carbon (soft carbon), and poorly graphitizable carbon (hard carbon). Carbon, carbon nanotubes, graphene, carbon black, etc. can be used. .

[0162] Examples of graphite include synthetic graphite and natural graphite. An example of synthetic graphite is Mesoca. Examples include carbon microbeads (MCMB), coke-based synthetic graphite, and pitch-based synthetic graphite. Here, spheroidal graphite, which has a spherical shape, can be used as artificial graphite. Furthermore, MCMB may have a spherical shape, which is preferable. Also, the surface area of ​​MCMB Reducing the size is relatively easy and sometimes preferable. Examples of natural graphite include, Examples include flaky graphite and spheroidized natural graphite.

[0163] Graphite is formed when lithium ions are inserted into it (during the formation of lithium-graphite intercalation compounds). It exhibits a potential as low as lithium metal (0.05V to 0.3V vs. Li / Li + This allows lithium-ion secondary batteries to exhibit a high operating voltage. Furthermore, graphite has a relatively high volume per unit volume, relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to lithium metal.

[0164] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4T) are used as negative electrode active materials. i5O 12 ), lithium-graphite intercalation compound (Li xC6), Niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0165] Furthermore, the negative electrode active material has a Li3N-type structure, which is a lithium and transition metal binitride. Li 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 The N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm²). 3 ) indicates And it is preferable.

[0166] When a lithium-transition metal binitride is used, lithium ions are included in the negative electrode active material, Combined with lithium-ion-free materials such as V2O5 and Cr3O8 as positive electrode active materials. This is preferable. By pre-desorbing the lithium ions contained in the positive electrode active material, the negative electrode active material is used. A lithium-transition metal composite can be used.

[0167] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, Lithium oxide, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO). Transition metal oxides that do not form alloys with the negative electrode active material may be used. The resulting materials include Fe2O3, CuO, Cu2O, RuO2, Cr2O3, etc. CoS oxides 0.89 , sulfides such as NiS and CuS, Zn3N2, Cu3N, Ge3 Nitrides such as N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. It can also occur with fluoride.

[0168] The conductive additives and binders that the negative electrode active material layer may have include the positive electrode active material layer Materials similar to conductive additives and binders can be used.

[0169] <Negative electrode current collector> The negative electrode current collector can be made of the same material as the positive electrode current collector. It is preferable to use a material that does not alloy with carrier ions such as thium.

[0170] [Electrolyte] An electrolyte solution contains a solvent and an electrolyte. A non-protic organic solvent is preferred as the solvent for the electrolyte solution. For example, ethylene carbonate (EC), propylene carbonate (PC), and buty Lenyl carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolane Chtone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl 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 sulfone Hoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetra One of the following: lahydrofuran, sulfolane, sultone, or two or more of these. It can be used in combinations and ratios.

[0171] Furthermore, as the solvent for the electrolyte, an ionic liquid (a room-temperature molten salt) that is flame-retardant and non-volatile is used. By using one or more of them, the internal temperature of the secondary battery rises due to internal short circuits or overcharging. This can also prevent secondary batteries from rupturing or catching fire. Ionic liquids contain cations and anions. It consists of organic cations and anions. As organic cations used in the electrolyte, quaternary cations are used. Ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, etc. aliphatic onium cations, imidazolium cations, pyridinium cations, etc. Aromatic cations are one example. Also, monovalent amide-based anions are used as anions in the electrolyte. Nions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Sulfonate anions, tetrafluoroborate anions, perfluoroalkyl borates Anions, hexafluorophosphate anions, or perfluoroalkyl phosphates Examples include anions.

[0172] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, and Li AsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4 Li2B 10 Cl 10 Li2B 12 Cl 12 LiCF3SO3, LiC4F9SO 3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2) 2. Lithium compounds such as LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. Using one type of um salt, or two or more of these salts in any combination and ratio. It is possible.

[0173] The electrolyte used in secondary batteries contains particulate matter and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "non-contaminated"). It is preferable to use a highly purified electrolyte with a low content of (also called "pure substance"). Specifically, the weight ratio of impurities to the electrolyte should be 1% or less, preferably 0.1% or less, more preferably It is preferable that the amount be 0.01% or less.

[0174] Furthermore, the electrolyte contains vinylene carbonate, propanesultone (PS), and tert-butylbe. TBB (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate) LiBOB (Lithium-Borate), as well as dinitriles such as succinonitrile and adiponitrile. Additives such as compounds may be added. The concentration of the added material should be, for example, relative to the total solvent. The concentration should be between 0.1 wt% and 5 wt%.

[0175] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used.

[0176] Using polymer gel electrolytes enhances safety against leakage and other issues. Furthermore, secondary batteries... It is possible to make it thinner and lighter.

[0177] Examples of polymers that can be gelled include silicone gel, acrylic gel, and acrylonitrile gel. Polyethylene oxide gels, polypropylene oxide gels, fluorine polymers Gels or similar materials can be used.

[0178] Examples of polymers include polyalkylene oxides such as polyethylene oxide (PEO). Polymers having a denture structure, PVDF, polyacrylonitrile, etc., and those Copolymers containing PVDF and hexafluoropropylene (H) can be used. For example, PVDF and hexafluoropropylene (H) PVDF-HFP, a copolymer of FP, can be used. The material may have a porous structure.

[0179] In addition, instead of an electrolyte, a solid electrolyte containing inorganic materials such as sulfide-based or oxide-based materials, or P Solid electrolytes containing polymer materials such as EO (polyethylene oxide) can be used. When using a solid electrolyte, the installation of separators and spacers becomes unnecessary. Because the entire pond can be solidified, the risk of leakage is eliminated, dramatically improving safety.

[0180] [Separator] Furthermore, it is preferable that the secondary battery has a separator. The separator can be, for example, paper. Nonwoven fabrics, glass fibers, ceramics, or nylon (polyamide), vinylon (poly Vinyl alcohol-based fibers, polyester, acrylic, polyolefin, polyurethane Materials made from synthetic fibers, etc., can be used. The separator is envelope-shaped. It is preferable to process it in such a way that it encloses either the positive or negative electrode.

[0181] 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 aluminium oxide. Aluminum particles, silicon oxide particles, etc. can be used. As for fluorine-based materials, For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide materials Materials used include, for example, nylon and aramid (meta-aramid, para-aramid). It is possible.

[0182] Coating with ceramic materials improves oxidation resistance, thus preventing separation during high-voltage charging and discharging. This can suppress degradation of the battery and improve the reliability of secondary batteries. Furthermore, by using fluorine-based materials... This allows the separator and electrodes to adhere more closely, improving the output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, thus increasing the safety of secondary batteries. It can improve overall health.

[0183] For example, a mixture of aluminum oxide and aramid material is applied to both sides of a polypropylene film. It may also be done by applying aluminum oxide to the surface of the polypropylene film that is in contact with the positive electrode. A mixed material of um and aramid may be coated, and a fluorine-based material may be coated on the surface in contact with the negative electrode. .

[0184] Using a multilayer separator ensures the safety of the secondary battery even if the overall thickness of the separator is thin. Because it can maintain this state, the capacity per unit volume of a secondary battery can be increased.

[0185] [Exterior] For the casing of a secondary battery, metal materials such as aluminum or resin materials are used. It is possible to use a film-like outer covering. As for the film, For example, polyethylene, polypropylene, polycarbonate, ionomer, polyamide, etc. A film made of the following materials, with highly flexible gold such as aluminum, stainless steel, copper, and nickel. A thin metal film is provided, and on the metal thin film, a polyamide resin and polyester resin are used as the outer surface of the exterior body. A three-layer film with an insulating synthetic resin film, such as a ru-based resin, can be used.

[0186] [Charge / discharge method] The charging and discharging of a secondary battery can be performed, for example, as follows.

[0187] ≪CC charging≫ First, let's explain CC charging as one of the charging methods. CC charging is used throughout the entire charging period. This charging method involves supplying a constant current to the secondary battery and stopping the charging process when a predetermined voltage is reached. The secondary battery is assumed to be an equivalent circuit of internal resistance R and secondary battery capacity C, as shown in Figure 7(A). In this case, the secondary battery voltage V B This is the voltage V across the internal resistance R. R and secondary battery capacity C The voltage V C It is the sum of.

[0188] While CC charging is in progress, the switch turns on as shown in Figure 7(A), and a certain amount of power is supplied. Current I flows through the secondary battery. During this time, since the current I is constant, V R Ohm's law = R × I According to the law, the voltage V across the internal resistance R is R It is also constant. On the other hand, the electricity applied to the secondary battery capacity C Pressure V C The voltage increases over time. Therefore, the secondary battery voltage V B The passage of time and They both rise.

[0189] And the secondary battery voltage V B Charging stops when the voltage reaches a predetermined level, for example, 4.3V. When CC charging is stopped, the switch turns off as shown in Figure 7(B), and the current I=0 Therefore, the voltage V across the internal resistance R is... R The voltage becomes 0V. Therefore, the internal resistance R The voltage drop is eliminated, and the secondary battery voltage V B It will decline.

[0190] The secondary battery voltage V during CC charging and after CC charging has stopped. B and charging current An example is shown in Figure 7(C). The secondary battery voltage V was rising while CC charging was being performed. B However, C The image shows a slight decrease after C charging is stopped.

[0191] ≪CCCV charging≫ Next, we will explain CCCV charging, which is a different charging method from the one described above. CCCV charging is First, the battery is charged to a predetermined voltage using CC charging, and then the current that flows through it is charged using CV (constant voltage) charging. This charging method continues until the current level drops to a minimum, specifically until it reaches the cutoff current value.

[0192] While CC charging is in progress, the constant current power supply switch is turned on, as shown in Figure 8(A). The voltage power supply switch is turned off, and a constant current I flows to the secondary battery. During this time, the current I Since it is constant, V R According to Ohm's law, =R × I, the voltage across the internal resistance R is V. R one It is constant. On the other hand, the voltage V across the secondary battery capacity C C It increases over time. Therefore, the secondary battery voltage V B It increases over time.

[0193] And the secondary battery voltage V B When the voltage reaches a predetermined level, for example 4.3V, CC charging is switched to C Switch to V charging. While CV charging is being performed, a constant voltage power supply is used as shown in Figure 8(B). The switch for the constant current power supply is turned on, and the secondary battery voltage V B It becomes constant On the other hand, the voltage V across the secondary battery capacity C... C It increases over time. B =V R +V C Therefore, the voltage V across the internal resistance R R It decreases over time. Voltage V across resistor R R As V decreases, RAccording to Ohm's law, =R × I, two The current I flowing through the next battery will also decrease.

[0194] And when the current I flowing through the secondary battery becomes a predetermined current, for example, a current equivalent to 0.01C... , stop charging. When CCCV charging is stopped, all switches will turn off as shown in Figure 8(C). The switch turns off, and the current I becomes 0. Therefore, the voltage V across the internal resistance R is lost. R The voltage becomes 0V. However, the voltage V across the internal resistance R due to CV charging R Because it has become small enough Even if the voltage drop across the internal resistance R disappears, the secondary battery voltage V B It hardly descends at all.

[0195] The secondary battery voltage V during CCCV charging and after CCCV charging has stopped. B and An example of electric current is shown in Figure 8(D). Even when CCCV charging is stopped, the secondary battery voltage V B Mostly It appears that it is not descending at all.

[0196] ≪CC discharge≫ Next, we will explain CC discharge, one of the discharge methods. CC discharge is used throughout the entire discharge period. A constant current is drawn from the secondary battery, and the secondary battery voltage V B When it reaches a predetermined voltage, for example 2.5V This is a discharge method that stops the discharge when it reaches a certain point.

[0197] The secondary battery voltage V during CC discharge B Figure 9 shows an example of the discharge current. Therefore, the secondary battery voltage V B The image shows it descending.

[0198] Next, we will explain the discharge rate and charge rate. The discharge rate is the ratio of the battery capacity to the charge rate. This is the relative ratio of the current during discharge, and is expressed in units of cubic centimeters (C). Therefore, the current equivalent to 1C is X(A). If discharged with a current of 2X(A), then 2C If it was discharged with a current of X / 5(A), then it was discharged at 0.2C. It is said that the charging rate is also similar; if charged with a current of 2X(A), it will charge at 2C. They said they charged it, and if they charged it with a current of X / 5(A), they said they charged it at 0.2C. .

[0199] (Embodiment 3) In this embodiment, the shape of the secondary battery having the positive electrode active material 100 described in the previous embodiment is Let's explain an example. The material used in the secondary battery described in this embodiment is the same as in the previous embodiment. The description of the state can be taken into consideration.

[0200] [Coin-type rechargeable battery] First, let's explain an example of a coin-type rechargeable battery. Figure 10(A) shows a coin-type (single-layer flat type) Figure 10(B) is an external view of the secondary battery, and Figure 10(B) is a cross-sectional view thereof.

[0201] The coin-type rechargeable battery 300 consists of a positive electrode casing 301, which also serves as the positive terminal, and a negative electrode casing, which also serves as the negative terminal. 302 is insulated and sealed by 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 306 provided in contact with it. It is formed by the following. The negative electrode 307 is provided in contact with the negative electrode current collector 308. It is formed by a negative electrode active material layer 309.

[0202] Furthermore, the positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 each have The active material layer only needs to be formed on one side.

[0203] The positive electrode container 301 and the negative electrode container 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. , metals such as titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel) (etc.) can be used. In addition, nickel and aluminum can be used to prevent corrosion by the electrolyte. It is preferable to cover it with a material such as a nut. The positive electrode can 301 is the positive electrode 304, and the negative electrode can 302 is the negative electrode 30 Connect each of the 7s electrically.

[0204] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with the electrolyte, as shown in Figure 10(B As shown in the image, with the positive electrode can 301 at the bottom, the positive electrode 304, separator 310, and negative electrode 307, The negative electrode cans 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected by a gasket 303. The coin-type secondary battery 300 is manufactured by crimping the parts together.

[0205] By using the positive electrode active material described in the previous embodiment for the positive electrode 304, high capacity cycle This allows for the creation of a coin-type secondary battery 300 with superior characteristics.

[0206] Here, we will use Figure 10(C) to explain the current flow during the charging of a secondary battery. Using lithium When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of current are in the same direction. In addition, in lithium-ion secondary batteries, the anode and cathode are used during charging and discharging. The cathode is swapped, and the oxidation and reduction reactions are reversed, thus changing the reaction potential. The electrode with a high reaction potential is called the positive electrode, and the electrode with a low reaction potential is called the negative electrode. Therefore, in this specification... In this case, whether charging or discharging, or even when applying a reverse pulse current, Even when an electric current is flowing, the positive electrode is called the "positive electrode" or "+ electrode (positive pole)," and the negative electrode is called the "positive pole." This will be referred to as the "negative electrode" or "- electrode (minus electrode)". Related to oxidation and reduction reactions. Using the terms anode and cathode, the difference between charging and discharging is significant. This could be reversed and cause confusion. Therefore, the anode and cathode The term cathode will not be used in this specification. When using terms such as positive electrode () or cathode, specify whether it is during charging or discharging, and the positive electrode ( The corresponding polarity (positive or negative) should also be indicated.

[0207] The charger is connected to the two terminals shown in Figure 10(C), and the secondary battery 300 is charged. As the charging of the next battery 300 progresses, the potential difference between the electrodes will increase.

[0208] [Cylindrical rechargeable battery] Next, an example of a cylindrical secondary battery will be explained with reference to Figure 11. Cylindrical secondary battery 600 As shown in Figure 11(A), it has a positive electrode cap (battery cover) 601 on the top surface, and the sides and The bottom surface has a battery can (outer casing) 602. These positive electrode cap and battery can (outer casing) 602 is insulated by gasket (insulating packing) 610.

[0209] Figure 11(B) is a schematic diagram showing a cross-section of a cylindrical secondary battery. Inside can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are separated by a separator 605. A wound battery element is provided. Although not shown in the diagram, the battery element is centered around the center pin. It is wound up. Battery can 602 is closed at one end and open at the other end. This is a metal such as nickel, aluminum, or titanium that is corrosion-resistant to the electrolyte, or this These alloys or alloys of these with other metals (for example, stainless steel) can be used. Furthermore, to prevent corrosion from the electrolyte, nickel, aluminum, etc., are coated onto the battery can 602. It is preferable that the positive electrode, negative electrode and separator are wound inside the battery can 602. The battery element is sandwiched between a pair of opposing insulating plates 608 and 609. The inside of the battery can 602, which is equipped with a battery element, is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte can be the same as that used in coin-type rechargeable batteries.

[0210] Since the positive and negative electrodes used in cylindrical secondary batteries are wound, active material is formed on both sides of the current collector. It is preferable to do so. The positive electrode 604 is connected to the positive electrode terminal (positive electrode current collector lead) 603, and the negative The negative terminal (negative current collector lead) 607 is connected to pole 606. The positive terminal 603 and the negative Both electrode terminals 607 can be made of metal materials such as aluminum. Positive electrode terminal 6 Terminal 03 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 uses a PTC element (Positive Temperature C It is electrically connected to the positive electrode cap 601 via the efficient)611. The safety valve mechanism 612 activates the positive electrode cap 601 when the internal pressure of the battery rises above a predetermined threshold. This disconnects the electrical connection between the positive electrode 604 and the positive electrode 611. Also, the PTC element 611 is at a certain temperature. This is a thermal resistance element whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. This prevents abnormal heat generation. The PTC element uses barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0211] Furthermore, as shown in Figure 11(C), multiple secondary batteries 600 are connected to conductive plates 613 and 614 Module 615 may be configured by sandwiching it between them. Multiple secondary batteries 600 are connected in parallel. They may be connected in series, or connected in parallel and then further connected in series. It may be done. By configuring a module 615 having multiple secondary batteries 600, It can extract a large amount of power.

[0212] Figure 11(D) is a top view of module 615. The conductive plate 613 is shown in the diagram for clarity. This is shown by the dotted line. As shown in Figure 11(D), module 615 has multiple secondary batteries 600 It may have electrically connected conductors 616. A conductive plate may be superimposed on the conductors 616. It is possible to have a temperature control device 617 between multiple secondary batteries 600. i. When the secondary battery 600 overheats, the temperature control device 617 cools it down, and the secondary battery 6 When 00 is too cold, it can be heated by the temperature control device 617. The performance of module 615 becomes less affected by ambient temperature. The heat of the temperature control device 617 The medium preferably has insulating and non-flammable properties.

[0213] By using the positive electrode active material described in the previous embodiment for the positive electrode 604, high capacity cycle This allows for the creation of a cylindrical secondary battery 600 with superior characteristics.

[0214] [Example of a secondary battery structure] Another example of a secondary battery structure will be explained using Figures 12 to 16.

[0215] Figures 12(A) and 12(B) show the external appearance of the secondary battery. The secondary battery 913 is It is connected to antennas 914 and 915 via circuit board 900. The secondary battery 913 has label 910 attached to it. Furthermore, as shown in Figure 12(B) The secondary battery 913 is connected to terminals 951 and 952.

[0216] The circuit board 900 has terminal 911 and circuit 912. Terminal 911 is connected to terminal 951 It is connected to terminal 952, antenna 914, antenna 915, and circuit 912. Multiple terminals 911 are provided, and each of the multiple terminals 911 is designated as a control signal input terminal and a power supply terminal. You could also do this.

[0217] The circuit 912 may be provided on the back surface of the circuit board 900. Furthermore, the antenna 914 and The antenna 915 is not limited to a coil shape, but may also be linear, plate-shaped, etc. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, dielectric Antennas such as antennas may be used. Alternatively, antenna 914 or antenna 915 may be used. Alternatively, a flat conductor may be used. This flat conductor functions as one of the conductors for electric field coupling. This is possible. In other words, as one of the two conductors of the capacitor, You may activate antenna 914 or antenna 915. This will allow only electromagnetic and magnetic fields to be generated. Alternatively, power can be exchanged using an electric field.

[0218] The line width of antenna 914 is preferably larger than the line width of antenna 915. Furthermore, the amount of power received can be increased by antenna 914.

[0219] The secondary battery has a layer 916 between antennas 914 and 915 and the secondary battery 913. It has the function of shielding electromagnetic fields, for example, from secondary batteries 913. It has. For layer 916, for example, a magnetic material can be used.

[0220] Note that the structure of the secondary battery is not limited to that shown in Figure 12.

[0221] For example, as shown in Figures 13(A-1) and 13(A-2), Figures 12(A) and 12 Antennas may be provided on each of the two opposing faces of the secondary battery 913 shown in (B). Figure 13(A-1) is an external view showing one of the pair of surfaces mentioned above, and Figure 13(A-2) is... This is an external view showing the other side of the pair of faces described above. Note that Figures 12(A) and 12(B) are shown below. For parts that are the same as those of a secondary battery, see the explanation of the secondary battery shown in Figures 12(A) and 12(B). It can be used as appropriate.

[0222] As shown in Figure 13(A-1), a layer 916 is sandwiched between one of the pair of surfaces of the secondary battery 913. An incubator 914 is provided, and as shown in Figure 13(A-2), a pair of sides of the secondary battery 913 On the other side, an antenna 918 is provided with a layer 917 in between. Layer 917 is, for example, a secondary battery 91 It has the function of shielding the electromagnetic field caused by 3. For layer 917, for example, a magnetic material. You can use it.

[0223] By adopting the above structure, the size of both antenna 914 and antenna 918 can be increased. It is possible. Antenna 918 can, for example, perform data communication with external devices. It has the function of being able to do so. Antenna 918 has an antenna shape that can be applied to, for example, antenna 914. An antenna can be applied. This is a communication method between a secondary battery and other devices via antenna 918. For example, it can be used between a rechargeable battery and other devices, such as NFC (Near Field Communication). A response method that can be applied can be used.

[0224] Alternatively, as shown in Figure 13(B-1), the secondary battery 9 shown in Figures 12(A) and 12(B) A display device 920 may be provided at 13. The display device 920 is electrically connected to terminal 911. It is not necessary to provide a label 910 in the area where the display device 920 is provided. For the same parts as the secondary battery shown in Figures 12(A) and 12(B), see Figures 12(A) and 12(B). The explanation of secondary batteries shown in Figure 12(B) can be used as appropriate.

[0225] The display device 920 displays, for example, an image indicating whether or not it is charging, an image indicating the amount of stored power, etc. It may be shown. The display device 920 may be, for example, electronic paper, liquid crystal display device, or electronic A luminescent (also known as EL) display device can be used. For example, an electronic paper By using this method, the power consumption of the display device 920 can be reduced.

[0226] Alternatively, as shown in Figure 13(B-2), the secondary battery 9 shown in Figures 12(A) and 12(B) A sensor 921 may be provided at 13. The sensor 921 is connected to terminal 911 via terminal 922. It is electrically connected. Note that it is located in the same part as the secondary battery shown in Figures 12(A) and 12(B). Accordingly, the explanation of secondary batteries shown in Figures 12(A) and 12(B) can be appropriately referenced.

[0227] Examples of sensors 921 include displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, and light. Liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, radiation, flow It should have the ability to measure quantity, humidity, gradient, vibration, odor, or infrared radiation. By providing the sensor 921, for example, data indicating the environment in which the secondary battery is placed can be collected. It can also detect (temperature, etc.) and store it in the memory within circuit 912.

[0228] Furthermore, an example of the structure of the secondary battery 913 will be explained using Figures 14 and 15.

[0229] The secondary battery 913 shown in Figure 14(A) has terminals 951 and 952 inside the housing 930. It has a wound body 950. The wound body 950 is impregnated with 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 insulating material, etc. It is not in contact with the body 930. Note that in Figure 14(A), for convenience, the housing 930 is separated. As shown in the diagram, in reality the wound body 950 is covered by the housing 930, and terminals 951 and 95 2 extends outside the casing 930. The casing 930 is made of a metal material (e.g., aluminum). Materials such as lum or resin can be used.

[0230] Furthermore, as shown in Figure 14(B), the housing 930 shown in Figure 14(A) is made of multiple materials. They may be formed. For example, the secondary battery 913 shown in Figure 14(B) has a housing 930a and a housing 9 30b is bonded together, and the area enclosed by the housing 930a and housing 930b is wound up 9 50 is provided.

[0231] For the casing 930a, insulating materials such as organic resin can be used. In particular, the antenna By using a material such as organic resin on the surface where the electric field of the secondary battery 913 is formed, Shielding can be suppressed. Furthermore, if the shielding of the electric field by the housing 930a is small, the housing 930a Antennas such as antenna 914 and antenna 915 may be installed inside. For example, metal materials can be used.

[0232] Furthermore, the structure of the wound body 950 is shown in Figure 15. The wound body 950 consists of a negative electrode 931 and a positive electrode. It has poles 932 and separators 933. The coiled body 950 sandwiches the separators 933. The negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the stacked sheet is wound up to form a wound body. Furthermore, the stacking of the negative electrode 931, the positive electrode 932, and the separator 933 is further multiplied. You can do it multiple times.

[0233] The negative electrode 931 is connected to terminal 911 shown in Figure 12 via either terminal 951 or terminal 952. The positive terminal 932 is connected to terminal 91 shown in Figure 12 via terminal 951 and the other terminal 952. It connects to 1.

[0234] By using the positive electrode active material described in the previous embodiment for the positive electrode 932, high capacity cycle This allows for the creation of a secondary battery 913 with superior characteristics.

[0235] [Laminated rechargeable battery] Next, an example of a laminate-type secondary battery will be explained with reference to Figures 16 to 22. If a laminate-type secondary battery has a flexible structure, the number of flexible parts can be reduced. If implemented in electronic devices that also possess some of these features, the secondary battery can also be bent in accordance with the deformation of the electronic device. can.

[0236] Using Figure 16, we will explain the laminated secondary battery 980. The battery 980 has a wound body 993 as shown in Figure 16(A). The wound body 993 has a negative electrode 994 It has a positive electrode 995 and a separator 996. The wound body 993 is explained in Figure 15. Similar to the wound body 950, the negative electrode 994 and the positive electrode 995 overlap with the separator 996 in between. The sheets are joined together and laminated, and then the laminated sheets are rolled up.

[0237] The number of layers in the stack consisting of the negative electrode 994, positive electrode 995, and separator 996 is the required number of layers. The design should be appropriate depending on the capacitance and element volume. The negative electrode 994 is connected to the lead electrode 997 and the lead One side of the electrode 998 is connected to the negative electrode current collector (not shown), and the positive electrode 995 is connected to the lead electrode It is connected to a positive electrode current collector (not shown) via pole 997 and the other of lead electrode 998.

[0238] As shown in Figure 16(B), there is a film 981 which will be the outer casing and a film 98 which has a recess. The aforementioned coiled body 993 is housed in the space formed by bonding 2 together by heat pressing or the like. As a result, a secondary battery 980 can be manufactured as shown in Figure 16(C). (Winding body 99) 3 has lead electrodes 997 and 998, a film 981 and a recess The film 982 is impregnated with an electrolyte solution inside it.

[0239] Film 981 and film 982 having a recess are made of a metal material such as aluminum. or resin materials can be used. Film 981 and film 982 having recesses If a resin material is used as the material, when an external force is applied, the film 981 and the recess will To create a rechargeable battery in which the film 982 can be deformed and is flexible. It is possible.

[0240] Furthermore, Figures 16(B) and 16(C) show examples where two films are used, A space is formed by folding a single film, and the aforementioned wound body 99 is placed in that space. You may store 3.

[0241] By using the positive electrode active material described in the previous embodiment for the positive electrode 995, high capacity cycle This allows for the creation of a secondary battery 980 with superior characteristics.

[0242] Figure 16 also shows a secondary battery 9 having a wound body in a space formed by a film that serves as the outer casing. I have explained 80 examples, but for example, as shown in Figure 17, the shape is formed by the film that forms the outer casing. In the resulting space, it can also be used as a secondary battery having multiple strip-shaped positive electrodes, separators, and negative electrodes. good.

[0243] The laminated secondary battery 500 shown in Figure 17(A) consists of a positive electrode current collector 501 and a positive electrode active material The positive electrode 503 has a solid layer 502, and the negative electrode has a current collector 504 and a negative electrode active material layer 505. It has a negative electrode 506, a separator 507, an electrolyte 508, and an outer casing 509. A separator 507 is installed between the positive electrode 503 and the negative electrode 506 located within the body 509. It is. Also, the inside of the outer casing 509 is filled with electrolyte 508. The electrolyte 508 contains actual The electrolyte shown in Form 2 of the application can be used.

[0244] In the laminate-type secondary battery 500 shown in Figure 17(A), the positive electrode current collector 501 and the negative electrode current collector are... The polar current collector 504 also serves as a terminal for obtaining electrical contact with the outside. Therefore, it is the positive electrode. Parts of the current collector 501 and the negative electrode current collector 504 are exposed to the outside from the outer casing 509. They may also be arranged in this manner. Furthermore, the positive electrode current collector 501 and the negative electrode current collector 504 may be separated from the outer casing 509. Without exposing it to the outside, lead electrodes are used to connect the lead electrodes to the positive electrode current collector 501, or to the negative electrode. The lead electrodes may be exposed to the outside by ultrasonic bonding with the current collector 504.

[0245] In the laminated secondary battery 500, the outer casing 509 is made of, for example, polyethylene, poly On a film made of materials such as propylene, polycarbonate, ionomer, and polyamide, A highly flexible metal thin film such as aluminum, stainless steel, copper, or nickel is provided, and further, the metal An insulating synthetic resin such as polyamide resin or polyester resin is used as the outer surface of the outer casing on a thin film. A three-layer film with a lipid film can be used.

[0246] Furthermore, an example of the cross-sectional structure of the laminate-type secondary battery 500 is shown in Figure 17(B). A) shows an example consisting of two current collectors for simplicity, but in reality, see Figure 17(B). As shown, it is composed of multiple electrode layers.

[0247] In Figure 17(B), the number of electrode layers is set to 16 as an example. However, the secondary battery 500 is flexible. In Figure 17(B), the negative electrode current collector 504 has 8 layers, The positive electrode current collector 501 has a structure of 8 layers, for a total of 16 layers. Figure 17(B) shows the negative electrode This shows a cross-section of the extraction section, where eight layers of negative electrode current collectors 504 are ultrasonically bonded. The number of electrode layers is not limited to 16; it can be more or fewer. This allows for the creation of a secondary battery with a larger capacity. Also, in cases where the number of electrode layers is small... In combination, it is possible to create a rechargeable battery that is thin and highly flexible.

[0248] Here, an example of the external view of the laminate-type secondary battery 500 is shown in Figures 18 and 19. Figure 1 Figures 8 and 19 show the positive electrode 503, negative electrode 506, separator 507, casing 509, and positive electrode lead. It has a lead electrode 510 and a negative lead electrode 511.

[0249] Figure 20(A) shows the external view of the positive electrode 503 and the negative electrode 506. The positive electrode 503 is the positive electrode current collector 50 The positive electrode has a positive electrode active material layer 502 formed on the surface of the positive electrode current collector 501. 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). Negative electrode 506 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 a tab region. The area and shape of the tab regions of the positive and negative electrodes are not limited to the example shown in Figure 20(A). I can't.

[0250] [Method for manufacturing laminated rechargeable batteries] Here, an example of a method for manufacturing a laminate-type secondary battery, as shown in Figure 18, is presented in Figure 20. We will explain using (B) and (C).

[0251] First, the negative electrode 506, separator 507, and positive electrode 503 are stacked. (See Figure 20(B) for details.) The negative electrode 506, separator 507, and positive electrode 503 are shown. Here, there are 5 sets of negative electrodes and 5 sets of positive electrodes. An example of using four sets is shown. Next, the joining of the tab regions of the positive electrode 503 and the tab of the outermost positive electrode. The positive lead electrode 510 is joined to the region. For joining, for example, ultrasonic welding can be used. Good. Similarly, the bonding of the tab regions of the negative electrode 506 and the negative electrode connection to the tab region of the outermost negative electrode The electrode 511 is joined.

[0252] Next, the negative electrode 506, separator 507, and positive electrode 503 are placed on the outer casing 509.

[0253] Next, as shown in Figure 20(C), the outer casing 509 is folded at the part indicated by the dashed line. Next, the outer perimeter of the exterior body 509 is joined. For joining, for example, heat compression bonding may be used. In order to allow the electrolyte 508 to be added later, a part (or one side) of the outer casing 509 A region that is not connected (hereinafter referred to as the inlet) is provided.

[0254] Next, the electrolyte 508 (not shown) is introduced into the outer casing 509 through the inlet provided in the outer casing 5 Introduce into the inside of 09. Introduce electrolyte 508 under reduced pressure or inert gas atmosphere. It is preferable to do this below. And finally, join the inlet. In this way, lamination A secondary battery of type T, called secondary battery 500, can be manufactured.

[0255] By using the positive electrode active material described in the previous embodiment for the positive electrode 503, high capacity cycle This allows for the creation of a secondary battery 500 with superior characteristics.

[0256] [Bendable rechargeable battery] Next, an example of a bendable secondary battery will be described with reference to Figures 21 and 22. .

[0257] Figure 21(A) shows a schematic top view of a bendable secondary battery 250. Figure 21(B1 ), (B2), and (C) respectively correspond to the cutting lines C1-C2 and C3- in Figure 21(A). C4 is a schematic cross-sectional view at the cutting line A1-A2. The secondary battery 250 is connected to the outer casing 251 and It has a positive electrode 211a and a negative electrode 211b housed inside the outer casing 251. Lead 212a is electrically connected to 1a, and lead 211b is electrically connected to the negative electrode. Code 212b extends to the outside of the outer casing 251. Also, the area enclosed by the outer casing 251 In addition to the positive electrode 211a and the negative electrode 211b, an electrolyte (not shown) is sealed inside. .

[0258] The positive electrode 211a and negative electrode 211b of the secondary battery 250 will be explained using Figure 22. Figure 22(A) shows the stacking order of the positive electrode 211a, negative electrode 211b, and separator 214. This is an explanatory perspective view. Figure 22(B) shows the positive electrode 211a and the negative electrode 211b, as well as the Lee This is a perspective view showing lead 212a and lead 212b.

[0259] As shown in Figure 22(A), the secondary battery 250 has multiple strip-shaped positive electrodes 211a, and multiple short It has a booklet-shaped negative electrode 211b and a plurality of separators 214. Positive electrode 211a and negative electrode 2 Each of the 11b has a protruding tab portion and a portion other than the tab. One of the positive electrodes 211a A positive electrode active material layer is formed on the part of the surface other than the tab, and on the part of one side of the negative electrode 211b other than the tab A negative electrode active material layer is formed in minutes.

[0260] The sides of the positive electrode 211a where the positive electrode active material layer is not formed, and the negative electrode active material of the negative electrode 211b The positive electrode 211a and the negative electrode 211b are stacked so that surfaces without a layer are in contact with each other. It will be done.

[0261] Furthermore, the surface on which the positive electrode active material layer of the positive electrode 211a is formed and the negative electrode active material layer of the negative electrode 211b are formed A separator 214 is provided between the formed surfaces. In Figure 22, the separator is shown for clarity. Line 214 is shown with a dotted line.

[0262] Also, as shown in Figure 22(B), the multiple positive electrodes 211a and leads 212a are connected at the joint 215 They are electrically connected at a. The multiple negative electrodes 211b and leads 212b are connected at joint 2 Electrically connected at 15b.

[0263] Next, the exterior body 251 will be explained using Figures 21(B1), (B2), (C), and (D). ru.

[0264] The outer casing 251 has a film-like shape and sandwiches the positive electrode 211a and the negative electrode 211b. It is folded in two. The outer casing 251 has a folded portion 261 and a pair of sealing portions 2 It has 62 and a sealing portion 263. The pair of sealing portions 262 are positive electrode 211a and negative electrode It is provided on either side of pole 211b and can also be called a side seal. Also, seal portion 26 3 has a portion that overlaps with leads 212a and 212b, and is also called the top seal. It is possible.

[0265] The outer casing 251 has a ridge line 271 and a valley line 2 in the portion that overlaps with the positive electrode 211a and the negative electrode 211b. It is preferable that the 72 have a wave shape arranged alternately. Also, the sealing portion 26 of the outer casing 251 2 and the sealing portion 263 are preferably flat.

[0266] Figure 21(B1) shows a cross-section cut at the point where it overlaps with ridge line 271, and Figure 21(B2) shows... This is a cross-section taken at the point where it overlaps with valley line 272. Figures 21(B1) and (B2) are both secondary. This corresponds to the cross-section in the width direction of the battery 250 and the positive electrode 211a and negative electrode 211b.

[0267] Here, the ends in the width direction of the positive electrode 211a and the negative electrode 211b, i.e., the positive electrode 211a and The distance La is defined as the distance between the end of the negative electrode 211b and the seal portion 262. (Secondary battery 250) When deformation such as bending is applied, the positive electrode 211a and the negative electrode 211b become longer, as will be described later. They deform so that they are offset from each other in the opposite direction. In this case, if the distance La is too short, the outer casing 251 and The positive electrode 211a and the negative electrode 211b rub against each other strongly, which can damage the outer casing 251. In particular, when the metal film of the outer casing 251 is exposed, the metal film corrodes due to the electrolyte. There is a risk of being eaten. Therefore, it is preferable to set the distance La as long as possible. However, if the distance La is made too large, the volume of the secondary battery 250 will increase.

[0268] Furthermore, the thicker the combined thickness of the stacked positive electrode 211a and negative electrode 211b, the greater the positive electrode 211 It is preferable to increase the distance La between a and the negative electrode 211b and the seal portion 262. .

[0269] More specifically, stacked positive electrode 211a and negative electrode 211b and separate (not shown) When the total thickness of -214 is denoted as thickness t, the distance La is 0.8 times the thickness t or greater than 3.0. Two times or less, preferably 0.9 times or more and 2.5 times or less, more preferably 1.0 times or more and 2.0 times or less It is preferable that it be lower. By setting the distance La to this range, it becomes compact and easy to bend. This enables the creation of highly reliable batteries.

[0270] Furthermore, when the distance between the pair of sealing portions 262 is denoted as distance Lb, distance Lb is set to the positive electrode 211a and to be sufficiently larger than the width of the negative electrode 211b (here, the width Wb of the negative electrode 211b). This is preferable. This allows the secondary battery 250 to withstand repeated bending and other deformations. Even if the positive electrode 211a and the negative electrode 211b come into contact with the outer casing 251, the positive electrode 211a and the negative electrode Because a portion of the pole 211b can be shifted in the width direction, the positive pole 211a and the negative pole 211b This effectively prevents the outer casing 251 from rubbing against each other.

[0271] For example, the difference between the distance La between the pair of sealing portions 262 and the width Wb of the negative electrode 211b is the positive electrode The thickness t of 211a and the negative electrode 211b is 1.6 times or more and 6.0 times or less, preferably 1.8 times. It is preferable that the ratio is 5.0 times or less, and more preferably 2.0 times or more and 4.0 times or less. .

[0272] In other words, it is preferable that the distance Lb, width Wb, and thickness t satisfy the relationship shown in Equation 1 below. It's nice.

[0273]

number

[0274] Here, a is 0.8 or more and 3.0 or less, preferably 0.9 or more and 2.5 or less, more preferably It satisfies the condition of being between 1.0 and 2.0.

[0275] Figure 21(C) shows a cross-section including lead 212a, secondary battery 250, and positive electrode 211a. And it corresponds to the longitudinal cross-section of the negative electrode 211b. As shown in Figure 21(C), it is bent. In section 261, the longitudinal ends of the positive electrode 211a and the negative electrode 211b, and the outer casing 251 It is preferable to have a space 273 between it and the other.

[0276] Figure 21(D) shows a schematic cross-sectional view of the secondary battery 250 when bent. This corresponds to the cross-section at the cutting line B1-B2 in Figure 21(A).

[0277] When the secondary battery 250 is bent, a portion of the outer casing 251 located on the outside of the bend stretches, and a portion located on the inside stretches. Other parts that are placed will deform to shrink. More specifically, the parts located on the outside of the outer casing 251 The part deforms so that the wave amplitude is small and the wave period is large. Meanwhile, the outer casing 2 The portion located inside 51 is deformed so that the wave amplitude is large and the wave period is small. In this way, the exterior body 251 deforms, and as it bends, the exterior body 251 is affected. Because the stress is relieved, the material that makes up the exterior 251 does not need to expand or contract. As a result, the outer casing 251 was not damaged, and the secondary battery 250 could be bent with little force. Cut.

[0278] Furthermore, as shown in Figure 21(D), when the secondary battery 250 is bent, the positive electrode 211a and the negative electrode 211b and the other are relatively shifted. At this time, multiple stacked positive electrodes 211a and Since one end of the negative electrode 211b on the sealing portion 263 side is fixed by the fixing member 217, Each component shifts such that the amount of displacement increases the closer it is to the bent portion 261. This causes the positive electrode The stress on 211a and the negative electrode 211b is relieved, and the positive electrode 211a and the negative electrode 211b The device itself does not need to expand or contract. As a result, the positive electrode 211a and the negative electrode 211b are not damaged. It can bend a 250-cell secondary battery without any problems.

[0279] Furthermore, there is a space 273 between the positive electrode 211a and the negative electrode 211b and the outer casing 251. As a result, the positive electrode 211a and the negative electrode 211b, which are located on the inside when bent, are positioned within the outer casing 251 It can shift relative to each other without making contact.

[0280] The secondary battery 250 illustrated in Figures 21 and 22 can withstand repeated bending and straightening, and the outer casing remains intact. Damage to the body, damage to the positive electrode 211a and negative electrode 211b are less likely to occur, and the battery characteristics do not deteriorate. It is a difficult battery. The positive electrode 211a of the secondary battery 250 is as described in the previous embodiment. By using a positive electrode active material, it is possible to create a battery with even better cycle characteristics.

[0281] (Embodiment 4) This embodiment describes an example in which a secondary battery, which is one aspect of the present invention, is mounted in an electronic device. do.

[0282] First, as described in part of Embodiment 3, a bendable secondary battery is mounted in an electronic device. Examples are shown in Figures 23(A) to 23(G). An electronic device using a bendable secondary battery. As equipment, for example, television equipment (also called television or television receiver), Computer monitors, digital cameras, digital video cameras, digital photo Frame, mobile phone (also called mobile phone or mobile phone device), portable game console, mobile information Examples include terminals, audio playback devices, and large game machines such as pachinko machines.

[0283] Furthermore, rechargeable batteries with flexible shapes can be installed in the interior or exterior walls of houses and buildings, or in automobiles. It can also be incorporated along the curved surfaces of the interior or exterior.

[0284] Figure 23(A) shows an example of a mobile phone. Mobile phone 7400 has a housing 7401 In addition to the display unit 7402 incorporated into it, there are operation buttons 7403, an external connection port 7404, and It is equipped with a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 is secondary. It has a battery 7407. The secondary battery 7407 of the present invention is used This allows us to provide lightweight and long-lasting mobile phones.

[0285] Figure 23(B) shows the mobile phone 7400 in a curved state. Mobile phone 740 When the 0 is deformed by an external force and the whole thing is bent, the secondary battery located inside is revealed. The 7407 is also bent. Figure 23(C) shows the state of the bent secondary battery 7407 at that time. As shown in the diagram, the 7407 secondary battery is a thin rechargeable battery. The 7407 secondary battery is in a bent state. It is fixed in place. The secondary battery 7407 has lead electrodes 7 electrically connected to the current collector. It has 408. For example, the current collector is copper foil, partially alloyed with gallium to collect current. Improved adhesion with the active material layer that comes into contact with the body, ensuring the reliability of the 7407 secondary battery when it is bent. This configuration is highly balanced.

[0286] Figure 23(D) shows an example of a bangle-type display device. The portable display device 7100 is The device comprises a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. Figure 23(E) also shows the state of the bent secondary battery 7104. The secondary battery 7104 is bent. When worn on the user's arm in a distorted state, the casing deforms, causing part of the secondary battery 7104 or All curvatures change. Note that the degree of curvature at any point in the curve is equal to the radius of the corresponding circle. The value expressed as is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the radius of curvature Within a range of 40mm to 150mm, a portion of the main surface of the housing or secondary battery 7104 The whole thing changes. The radius of curvature on the main surface of secondary battery 7104 is 40 mm or more and 150 High reliability can be maintained within a range of mm or less. The present invention applies to the secondary battery 7104 described above. By using one embodiment of a secondary battery, a lightweight and long-lasting portable display device can be provided.

[0287] Figure 23(F) shows an example of a wristwatch-type personal information terminal. The personal information terminal 7200 is , housing 7201, display unit 7202, band 7203, buckle 7204, operation button 72 05. It is equipped with input / output terminals 7206, etc.

[0288] The 7200 mobile information terminal offers mobile phone, email, document viewing and creation, music playback, and internet connectivity. - It can run various applications such as network communication and computer games. ru.

[0289] The display unit 7202 has a curved display surface, and displays are made along the curved display surface. It can do this. In addition, the display unit 7202 is equipped with a touch sensor, allowing you to touch the screen with your finger or stylus. It can be operated by touching it. For example, the icon 72 displayed on the display unit 7202 Touching 07 will launch the application.

[0290] The 7205 control button is used for setting the time, turning the power on and off, and turning wireless communication on and off. It has various functions such as operation, silent mode activation and deactivation, and power saving mode activation and deactivation. This can be done. For example, the operating system built into the mobile information terminal 7200 The stem also allows you to freely configure the function of the control button 7205.

[0291] Furthermore, the personal information terminal 7200 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.

[0292] Furthermore, the portable information terminal 7200 is equipped with an input / output terminal 7206, and connects to other information terminals via a connector. It can directly exchange data via this. It can also be charged via input / output terminal 7206. It is also possible to perform this operation. Note that charging is performed wirelessly without using input / output terminal 7206. That's fine.

[0293] The display unit 7202 of the portable information terminal 7200 has a secondary battery according to one embodiment of the present invention. By using a secondary battery according to one aspect of the present invention, a lightweight and long-lasting portable information terminal can be provided. For example, the secondary battery 7104 shown in Figure 23(E) is placed inside the housing 7201 in a curved state. Alternatively, it can be incorporated into the band 7203 in a flexible state.

[0294] The personal information terminal 7200 preferably has a sensor. For example, a fingerprint sensor. Human body sensors such as pulse sensors and body temperature sensors, as well as touch sensors, pressure sensors, and acceleration sensors. It is preferable that the following are installed:

[0295] Figure 23(G) shows an example of an armband-type display device. The display device 7300 consists of a display unit 7 The present invention has a secondary battery having 304. The display device 7300 is a table The display unit 7304 can also be equipped with a touch sensor, and can function as a portable information terminal. It is also possible.

[0296] The display unit 7304 has a curved display surface, and displays are made along the curved display surface. Yes, it is possible. Furthermore, the display device 7300 can communicate via standardized short-range wireless communication, etc. The situation can be changed.

[0297] Furthermore, the display device 7300 is equipped with input / output terminals and can be directly connected to other information terminals via connectors. It can exchange data. It can also be charged via input / output terminals. Furthermore, charging may be performed wirelessly without using input / output terminals.

[0298] By using a secondary battery according to one aspect of the present invention as the secondary battery of the display device 7300, We can provide display devices with a long lifespan in large quantities.

[0299] Furthermore, the figure shows an example of mounting the secondary battery with good cycle characteristics shown in the previous embodiment into an electronic device. This will be explained using Figures 24 and 25, as shown in section 23(H).

[0300] By using a secondary battery according to one aspect of the present invention as a secondary battery in everyday electronic devices, a lightweight and long-lasting battery can be achieved. We can provide a variety of products. For example, as everyday electronic devices, electric toothbrushes, electric shavers, etc. Examples include mobile beauty devices, and the rechargeable batteries for these products are designed with ease of handling by the user in mind. What is desired is a rechargeable battery that is stick-shaped, small, lightweight, and has a large capacity.

[0301] Figure 23(H) is a perspective view of a device also known as a tobacco-containing smoking device (electronic cigarette). In 23(H), the electronic cigarette 7500 includes an atomizer 7501 containing a heating element, and The cart contains the 7504 rechargeable battery that powers the Myza, as well as liquid supply bottles, sensors, and other components. It consists of Ridge 7502. To enhance safety, overcharging of the secondary battery 7504 and over A protective circuit to prevent discharge may be electrically connected to the secondary battery 7504. (See Figure 23(H)) The secondary battery 7504 has external terminals so that it can be connected to a charging device. The 504 is the tip when held, so the overall length is short and the weight is light. This is desirable. A secondary battery according to one aspect of the present invention has high capacity and good cycle characteristics, We offer the 7500, a small and lightweight e-cigarette that can be used for extended periods of time. It can be used.

[0302] Next, Figures 24(A) and 24(B) show an example of a foldable tablet device. The tablet terminal 9600 shown in Figures 24(A) and 24(B) has a housing 9630. a, housing 9630b, movable part 9640 connecting housing 9630a and housing 9630b, display Section 9631, display mode switching switch 9626, switch 9627, switch 962 5. It has fasteners 9629 and an operating switch 9628. The display unit 9631 has flexibility By using the panel, it is possible to create a tablet device with a larger display area. Figure 24(A) shows the tablet terminal 9600 in an open state, and Figure 24(B) shows, This shows the tablet device 9600 in a closed state.

[0303] Furthermore, the tablet terminal 9600 stores energy inside the housings 9630a and 9630b. It has a body 9635. The energy storage body 9635 passes through the movable part 9640 and the housing 9630a and housing It is located across 9630b.

[0304] The display unit 9631 can have all or part of its area designated as a touch panel area, and By touching the image, text, input form, etc., including the icon displayed in that area, data can be collected. It is possible to input text. For example, the entire surface of the display unit 9631 on the chassis 9630a can be used for keyboard input. The button is displayed, and information such as text and images is shown on the display unit 9631 on the housing 9630b. It may be displayed and used.

[0305] Furthermore, the keyboard is displayed on the display unit 9631 on the chassis 9630b side, and the chassis 9630a side The display unit 9631 may be used to display information such as characters and images. Display the touch panel keyboard display switch button at 31, and then press the button. By touching it with a finger or stylus, keyboard buttons will be displayed on the display unit 9631. You may do so.

[0306] Furthermore, switches 9625 to 9627 operate the tablet terminal 9600. It is not just an interface for that purpose, but also an interface that can switch between various functions. It may also be a face. For example, at least one of switches 9625 to 9627 This functions as a switch to turn the power of the tablet device 9600 on and off. This is also fine. Also, for example, at least one of switches 9625 to 9627 is vertically oriented. Functions to switch the display orientation, such as horizontal or horizontal display, or switching between black and white and color display. They may also have the function of, for example, switches 9625 to 9627 The display unit 9631 may also have a function to adjust the brightness of the display unit 9631. The brightness is determined by the ambient light during use, as detected by the light sensor built into the tablet device 9600. The configuration can be optimized according to the amount of light. Note that the tablet terminal is a light sensor. In addition, it incorporates other detection devices such as gyroscopes, accelerometers, and other sensors that detect tilt. It's okay to store it.

[0307] Figure 24(B) shows the tablet terminal 9600 in a folded state. The terminal type 9600 includes a housing 9630, a solar cell 9633, and a DC-DC converter 9636. It has a charge / discharge control circuit 9634. Furthermore, as an energy storage body 9635, according to one aspect of the present invention A secondary battery is used.

[0308] As mentioned above, the 9600 tablet can be folded in half, so when not in use... The casings 9630a and 9630b can be folded so that they overlap. By folding it, the display unit 9631 can be protected, thus improving the durability of the tablet terminal 9600. It can improve performance. Furthermore, the energy storage body 9635 using a secondary battery according to one aspect of the present invention is high Because it has a large capacity and good cycle characteristics, it is a tablet that can be used for long periods of time over an extended period. We can provide the T-type terminal 9600.

[0309] In addition, the tablet terminal 9600 shown in Figures 24(A) and 24(B) is Features that display various information (still images, videos, text images, etc.), calendar, date or It has the function of displaying the time and other information on the display unit, and the ability to perform touch input operations or edit the information displayed on the display unit. Features such as touch input functionality, the ability to control processing through various software (programs), etc. It can have.

[0310] Power is supplied by a solar cell 9633 mounted on the surface of the tablet device 9600. It can be supplied to a panel, display unit, or video signal processing unit, etc. Note: Solar cell 963 3 can be provided on one or both sides of the housing 9630, and efficiently charges the energy storage unit 9635. This configuration can be used. Note that a lithium-ion battery can be used as the energy storage unit 9635. Having it offers advantages such as enabling miniaturization.

[0311] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 24(B) are shown in Figure 24( A block diagram is shown and explained in C). Figure 24(C) shows the solar cell 9633 and the energy storage unit 963. 5. DC-DC converter 9636, converter 9637, switch SW1 to SW3, table The diagram shows the section 9631, and includes the energy storage unit 9635, the DC-DC converter 9636, and the capacitor. The converter 9637 and switches SW1 to SW3 are connected to the charge / discharge control circuit 96 shown in Figure 24(B). This corresponds to section 34.

[0312] First, let's explain an example of operation when electricity is generated by the solar cell 9633 using ambient light. The electricity generated by the solar panel is converted to a DC-DC converter to provide the voltage needed to charge the 9635 energy storage unit. The converter 9636 performs voltage boosting or de-voltage adjustment. Then, the solar cell controls the operation of the display unit 9631. When power from 9633 is used, switch SW1 is turned ON, and converter 9637 The voltage is then boosted or lowered to the voltage required for the display unit 9631. If you do not want to display the data, turn off switch SW1 and turn on switch SW2 to store the data. The configuration should be such that the 9635 battery is charged.

[0313] The solar cell 9633 is shown as an example of a power generation method, but it is not particularly limited to this method. Energy storage using other power generation methods such as electrical elements (piezo elements) and thermoelectric conversion elements (Peltier elements) The configuration may also involve charging the body 9635. For example, power may be transmitted and received wirelessly (contactlessly). This configuration uses a contactless power transmission module for charging, or a combination of other charging methods. That's fine.

[0314] Figure 25 shows an example of another electronic device. In Figure 25, the display device 8000 is the first of the present invention. This is an example of an electronic device using a secondary battery 8004 according to the embodiment. Specifically, the display device 800 0 corresponds to a display device for receiving TV broadcasts, and consists of a housing 8001, a display unit 8002, and a speaker unit. The invention includes 8003, a secondary battery 8004, etc. A secondary battery 8004 according to one aspect of the present invention has a housing It is located inside the body 8001. The display device 8000 receives power from the commercial power supply. It can be used to power the device, or it can use the power stored in the secondary battery 8004. Even when power cannot be supplied from the commercial power source due to a power outage, etc., according to one aspect of the present invention By using the secondary battery 8004 as an uninterruptible power supply, the display device 8000 can be used. ru.

[0315] The display unit 8002 has light-emitting elements such as liquid crystal display devices and organic EL elements in each pixel. Equipment, electrophoresis display device, DMD (Digital Micromirror Display) ce), PDP (Plasma Display Panel), FED (Field Semiconductor display devices such as Emission Displays can be used.

[0316] In addition to being used for receiving TV broadcasts, display devices are also used for personal computers, advertising displays, and more. This includes all information display devices.

[0317] In Figure 25, the fixed lighting device 8100 is a secondary battery 81 according to one aspect of the present invention. This is an example of an electronic device using 03. Specifically, the lighting device 8100 has a housing 8101, and light It has a power source 8102, a secondary battery 8103, etc. In Figure 25, the secondary battery 8103 is located in the housing 81 An example is provided where 01 and the light source 8102 are installed inside the ceiling 8104. However, the secondary battery 8103 may also be located inside the housing 8101. The 8100 can receive power from the commercial power supply, or it can store power in the secondary battery 8103. It is also possible to use the accumulated power. Therefore, if power is not supplied from the commercial power source due to a power outage, etc. Even when it is not possible to receive a power supply, the secondary battery 8103 according to one aspect of the present invention can be used as an uninterruptible power supply. This makes it possible to use the lighting device 8100.

[0318] Note that Figure 25 illustrates a fixed lighting device 8100 installed on the ceiling 8104. However, in one aspect of the present invention, the secondary battery is located in a location other than the ceiling 8104, for example, the side wall 8105, the floor 8 106, It can also be used in fixed lighting devices installed in windows 8107, etc., and on a tabletop It can also be used in lighting fixtures and other similar devices.

[0319] Furthermore, the light source 8102 can be an artificial light source that uses electricity to artificially produce light. Specifically, this includes incandescent light bulbs, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements. The element is an example of the artificial light source mentioned above.

[0320] In Figure 25, the air conditioner having an indoor unit 8200 and an outdoor unit 8204 is, This is an example of an electronic device using a secondary battery 8203 according to one aspect of the present invention. Specifically, indoor The unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, etc. (See Figure 25) This example illustrates the case where the secondary battery 8203 is provided in the indoor unit 8200, but Battery 8203 may be located in the outdoor unit 8204. Alternatively, it may be located in the indoor unit 8200 and the outdoor unit. The secondary battery 8203 may be provided on both sides of the unit 8204. (Air conditioner) It can receive power from the commercial power supply, or from the electricity stored in the secondary battery 8203. It can also use force. In particular, both the indoor unit 8200 and the outdoor unit 8204 can use secondary batteries 82 If 03 is provided, when power cannot be supplied from the commercial power source due to a power outage, etc. Furthermore, by using the secondary battery 8203 according to one aspect of the present invention as an uninterruptible power supply, an air conditioner can be used. Conditioner can be used.

[0321] Note that Figure 25 shows a separate-type air conditioner consisting of an indoor unit and an outdoor unit. As an example, an integrated air conditioner has both the indoor and outdoor unit functions in a single housing. A secondary battery according to one aspect of the present invention can also be used in the conditioner.

[0322] In Figure 25, the electric refrigerator 8300 is powered by a secondary battery 8304 according to one aspect of the present invention. This is an example of the electronic equipment used. Specifically, the electric refrigerator 8300 consists of a casing 8301 and a refrigerator. It has a storage room door 8302, a freezer room door 8303, a secondary battery 8304, etc. In Figure 25, two The next battery 8304 is located inside the casing 8301. The electric refrigerator 8300 is, It can receive power from the commercial power supply, or it can use the power stored in the secondary battery 8304. It can also be used. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 according to one aspect of the present invention as an uninterruptible power supply, electric cooling The 8300 freezer / refrigerator will become available for use.

[0323] Of the electronic devices mentioned above, high-frequency heating devices such as microwave ovens and electric rice cookers are not included. The equipment requires high power in a short period of time. Therefore, it needs to supplement the power that cannot be supplied by the commercial power supply. By using a secondary battery according to one aspect of the present invention as an auxiliary power source for electronic devices, This prevents the commercial power circuit breaker from tripping during use.

[0324] Furthermore, during periods when electronic devices are not in use, especially the total amount of electricity that can be supplied by the commercial power source... Of these, during periods when the proportion of electricity actually used (called the electricity usage rate) is low, secondary By storing power in the battery, the rate of power consumption outside of the above-mentioned time period is suppressed. It is possible. For example, in the case of the electric refrigerator 8300, when the temperature is low, the refrigerator door 830 2. At night when the freezer door 8303 is not opened or closed, power is stored in the secondary battery 8304. And as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. During the daytime, by using the secondary battery 8304 as an auxiliary power source, the daytime power usage rate It can be kept low.

[0325] According to one aspect of the present invention, the cycle characteristics of a secondary battery are improved, and its reliability is enhanced. This is possible. Furthermore, according to one aspect of the present invention, a high-capacity secondary battery can be made, and therefore This allows for improved characteristics of secondary batteries, and therefore, the secondary batteries themselves can be made smaller and lighter. Yes, it is possible. Therefore, a secondary battery, which is one aspect of the present invention, can be used in the electronic device described in this embodiment. By incorporating this technology, electronic devices can be made longer-lasting and lighter. This can be implemented in appropriate combination with other embodiments.

[0326] (Embodiment 5) This embodiment shows an example in which a secondary battery according to one aspect of the present invention is mounted on a vehicle.

[0327] When a secondary battery is installed in a vehicle, it becomes a hybrid electric vehicle (HEV), an electric vehicle (EV), or a hybrid electric vehicle. This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid electric vehicles (PHEVs). .

[0328] Figure 26 illustrates a vehicle using a secondary battery, which is one embodiment of the present invention. Figure 26(A) The automobile 8400 shown is an electric vehicle that uses an electric motor as a power source for driving. Yes. Alternatively, an electric motor and an engine can be appropriately selected and used as the power source for propulsion. This is a hybrid vehicle that is capable of doing so by using a secondary battery, which is one aspect of the present invention. This makes it possible to create vehicles with a long driving range. Furthermore, the 8400 vehicle has a secondary battery. The secondary battery is located in the floor area of ​​the vehicle, as shown in Figures 11(C) and 11(D). You can use battery modules by arranging them in a row. Alternatively, you can combine multiple rechargeable batteries as shown in Figure 16. The battery pack may be installed on the floor inside the vehicle. The secondary battery powers the electric motor 840 In addition to driving the 6, it also emits light such as the headlights 8401 and interior lights (not shown). It can supply power to the device.

[0329] Furthermore, the secondary battery is used for the speedometer, tachometer, and other displays in the 8400 automobile. It can supply power to the device. In addition, the secondary battery is the navigation system of the 8400 automobile. It can supply power to semiconductor devices such as ignition systems.

[0330] The automobile 8500 shown in Figure 26(B) is a secondary battery that the automobile 8500 has a plug-in type It can be charged by receiving power from an external charging facility using methods such as contactless power supply. Figure 26(B) shows the two devices mounted on the automobile 8500, connected to the ground-mounted charging device 8021. The next diagram shows the state in which batteries 8024 and 8025 are being charged via cable 8022. When charging, the charging method and connector specifications are based on CHAdeMO (registered trademark) and Combo. The method may be carried out as appropriate in the prescribed manner. The charging device 8021 is a charging station installed in a commercial facility. It can be a power supply or a household power supply. For example, using plug-in technology, The secondary batteries 8024 and 8025 installed in the 8500 vehicle are charged by an external power supply. It can be charged. Charging is done by converting AC power directly through a converter such as an AC / DC converter. This can be done by converting it into electrical current.

[0331] 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 doing so. In this contactless power supply method, power transmission equipment is installed in roads or exterior walls. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. Furthermore, this contactless power supply... This method may be used to transmit and receive power between vehicles. Furthermore, the exterior of the vehicle Solar panels may be installed to charge the secondary battery when the vehicle is stopped or in motion. Electromagnetic induction or magnetic resonance methods can be used to supply power to it.

[0332] Furthermore, Figure 26(C) shows an example of a motorcycle using a secondary battery according to one embodiment of the present invention. Figure 26 The scooter 8600 shown in (C) includes a secondary battery 8602, side mirrors 8601, and turn signals. It is equipped with a light 8603. The secondary battery 8602 supplies electricity to the turn signal light 8603. can.

[0333] Furthermore, the scooter 8600 shown in Figure 26(C) has a secondary battery 860 in the under-seat storage 8604. It can store 2. The secondary battery 8602 can be stored even if the under-seat storage 8604 is small. It can be stored in the under-seat storage compartment 8604. The secondary battery 8602 is removable. When charging, the 8602 secondary battery is carried indoors, charged, and stored before driving. That's all you need to do.

[0334] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the capacity of the secondary battery is increased. This makes it possible to make the secondary battery itself smaller and lighter. Making the body smaller and lighter contributes to reducing the vehicle's weight, which in turn improves its driving range. It is possible. Furthermore, the secondary battery installed in the vehicle can also be used as a power source for purposes other than the vehicle itself. In this case, for example, it is possible to avoid using commercial power during peak electricity demand. If the use of commercial power can be avoided during peak electricity demand, energy conservation and two It can contribute to reducing carbon dioxide emissions. Furthermore, if the cycle characteristics are good, secondary... Because batteries can be used for extended periods, the amount of rare metals used, including cobalt, can be reduced. It is possible.

[0335] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0336] In this example, a positive electrode active material 100 according to one aspect of the present invention and lithium cobalt oxide of a comparative example were prepared. Next, I will explain the results of the analysis performed using XRD.

[0337] [Fabrication of positive electrode active material] ≪Sample 01≫ As sample 01 of a positive electrode active material according to one aspect of the present invention, magnesium and fluorine are used as starting materials. Lithium cobalt oxide particles were prepared by adding a certain element, and then the mixture was heated to produce the resulting product.

[0338] In Sample 01, as described in step S11 of Embodiment 1, the starting material is lithium Lithium carbonate as the source of magnesium, cobalt oxide as the source of cobalt, and magnesium oxide as the source of magnesium. We prepared lithium fluoride as a source of magnesium and fluorine. The ratio of each element was Li 1.0 2Co 0.99 Mg 0.01 O 1.98 F 0.02 The weights were measured to achieve the following result.

[0339] Next, in step S12, the starting materials were mixed. The mixture contained zirconia balls. The process was performed using a 360rpm machine for 2 hours at 250rpm.

[0340] Next, in step S13, the mixed material is placed in a crucible made of aluminum oxide (hereafter referred to as aluminum It was heated in a crucible (called a Na crucible). A muffle furnace was used, and the flow rate of the dry air atmosphere was The flow rate is set to 10 L / min, the holding temperature to 950°C (heating rate of 200°C / hour), and the holding time to 10 hours. The cooling time from the holding temperature to room temperature was set to between 10 and 15 hours.

[0341] Step S14 was omitted because the titanium and aluminum coating treatment was not performed.

[0342] Next, in step S15, the magnesium and fluorine synthesized in step S13 are used. Lithium cobalt oxide particles were placed in an alumina crucible and heated. Using a muffle furnace, oxygen The atmosphere flow rate is 10 L / min, and the holding temperature is 900°C (heating increase of 200°C / hour). The interval was set to 2 hours. The cooling time from the holding temperature to room temperature was set to 10 hours or more and 15 hours or less.

[0343] Afterward, a crushing process was carried out. The crushing process was done by sieving, and the sieve had a mesh size. A sample with a diameter of 53 μm was used.

[0344] Finally, the particles were collected to obtain the positive electrode active material for sample 01. The positive electrode was prepared under the conditions described above. It has been found that the concentration of magnesium and fluorine in the surface layer of the active material is higher than in the interior. It is.

[0345] ≪Sample 02≫ Sample 02 has magnesium and fluorine as a positive electrode active material according to one embodiment of the present invention. We prepared a product by heating lithium cobalt oxide particles.

[0346] In Sample 02, lithium cobalt oxide particles (manufactured by Nippon Chemical Industrial Co., Ltd.) were used as the starting material. Product name: C-20F) was used. Therefore, in Sample 02, the S explained in Embodiment 1 Steps S12 and S13 were omitted. Note that the lithium cobalt oxide particles mentioned above are granular The diameter (D50) is approximately 20 μm, and fluorine, magnesium, and ka are present in the region analyzable by XPS. These are lithium cobalt oxide particles containing calcium, sodium, silicon, sulfur, and phosphorus. Since the titanium and aluminum coating treatment was not performed, step S14 was also omitted.

[0347] Next, in step S15, lithium cobalt oxide particles were placed in an alumina crucible and heated. Using a muffle furnace, the flow rate of the dry air atmosphere is set to 5 L / min, and the holding temperature is 800°C (ascending temperature). The temperature was set to 200°C / hour, and the holding time was 2 hours. The time it took to cool down from the holding temperature to room temperature was 10 hours. The incubation period was set to between 15 hours and 15 hours. Afterward, it was sieved and collected in the same manner as sample 01. The positive electrode active material produced under the above conditions also has a higher concentration of magnesium and fluorine in the surface layer than in the interior. It is known that it will be higher than that.

[0348] ≪Sample 03≫ Sample 03 is a positive electrode active material according to one embodiment of the present invention, comprising magnesium and fluorine. A positive electrode active material was fabricated by coating lithium cobalt oxide particles with titanium using the sol-gel method.

[0349] In Sample 03, lithium cobalt oxide particles (manufactured by Nippon Chemical Industrial Co., Ltd.) were used as the starting material. Product name: C-20F) was used. Therefore, steps S12 and S13 were omitted. Ta.

[0350] Next, in step S14, the lithium cobalt oxide particles are coated with a titanium-containing material. Specifically, TTIP was dissolved in isopropanol, and the isopropanol of TTIP was used. A solution was prepared. Then, lithium cobalt oxide particles were mixed into the solution. TTIP is MAG Mix lithium cobalt oxide containing nesium and fluorine to a concentration of 0.004 ml / g. They combined.

[0351] This mixture was stirred with a magnetic stirrer for 72 hours at 25°C and 90% RH. The mixture was stirred without a lid. This process involved hydrolysis and polycondensation with water in the atmosphere and TTIP. The reaction is initiated, and titanium is added to the surface of lithium cobalt oxide particles containing magnesium and fluorine. A layer containing n was formed.

[0352] The mixture, after the above processing, was centrifuged, and the precipitate was recovered. Centrifugation was performed at 3000 rpm. This was done for 1 minute, and isopropanol was used for washing.

[0353] The recovered precipitate was dried in a forced-air drying oven at 70°C for 3 hours.

[0354] Next, in step S15, lithium cobalt oxide particles coated with a titanium-containing material are It was heated in an alumina crucible. A muffle furnace was used, with an oxygen atmosphere flow rate of 10 L / mi. Let n be the holding temperature, with a holding temperature of 800°C (heating rate of 200°C / hour) and a holding time of 2 hours. The cooling time to room temperature was set to between 10 and 15 hours. After that, the process was the same as for sample 01. It was sieved and recovered. The positive electrode active material produced under the above conditions consisted of titanium and magnesium in the surface layer. It has been found that the concentrations of nesium and fluorine are higher inside than outside. Also, the titanium concentration It has been found that the peak is located in a deeper region than the peak of magnesium concentration.

[0355] ≪Sample 04≫ Sample 04 is a positive electrode active material according to one aspect of the present invention, comprising magnesium and fluorine. A positive electrode active material was prepared by coating lithium cobalt oxide particles with aluminum using the sol-gel method. did.

[0356] In Sample 04, lithium cobalt oxide particles (manufactured by Nippon Chemical Industrial Co., Ltd.) were used as the starting material. Product name: C-20F) was used. Therefore, steps S12 and S13 were omitted. Ta.

[0357] Next, in step S14, the lithium cobalt oxide particles are mixed with an aluminum-containing material. It was coated. Specifically, aluminum isopropoxide was dissolved in isopropanol, An isopropanol solution of aluminum isopropoxide was prepared. Then, to this solution, Lithium baltate particles were mixed. Aluminum isopropoxide was mixed with magnesium and fluorine. It was mixed with lithium cobalt oxide containing the element at a concentration of 0.0279 g / g.

[0358] This mixture was heated in a magnetic stirrer for 8 hours at 25°C and 90% RH. The mixture was stirred without adding any other ingredients. This process involved adding aluminum isopropoxide to the water in the atmosphere. Lithium cobaltate, which undergoes water splitting and polycondensation reactions, contains magnesium and fluorine. A layer containing aluminum was formed on the surface of the particles.

[0359] The mixture after the above processing was filtered, and the residue was collected. Kiriyama filter paper was used for filtration. (No. 4) Isopropanol was used for washing.

[0360] The collected residue was dried in a vacuum bell jar at 70°C for 1 hour.

[0361] Next, in step S15, lithium cobalt oxide coated with a material having aluminum The particles were placed in an alumina crucible and heated. A muffle furnace was used, with an oxygen atmosphere flow rate of 10 L. The temperature was set to / min, the holding temperature to 800°C (heating increase of 200°C / hour), and the holding time to 2 hours. The cooling time from the temperature to room temperature was set to between 10 and 15 hours. After that, Sample 01 It was sieved and recovered in the same manner. The positive electrode active material prepared under the above conditions had an aluminum surface layer. It has been found that the concentrations of nium, magnesium, and fluorine are higher inside than outside. The peak of aluminum concentration is located in a deeper region than the peak of magnesium concentration. I understand.

[0362] ≪Sample 05≫ Sample 05, as a comparative example, consists of lithium cobalt oxide granules containing magnesium and fluorine. The child (manufactured by Nippon Chemical Industrial Co., Ltd., product name: C-20F) is processed without sol-gel treatment or heating. I used it as is.

[0363] ≪Sample 06≫ Sample 06 is a comparative example of lithium cobalt oxide that does not contain magnesium or fluorine. The particles were coated with aluminum using the sol-gel method.

[0364] In Sample 06, lithium cobalt oxide particles (manufactured by Nippon Chemical Industrial Co., Ltd.) were used as the starting material. Product name: C-5H) was used. Therefore, steps S12 and S13 were omitted. The lithium cobalt oxide particles mentioned above have a particle size (D50) of approximately 5 μm, and can be analyzed using XPS, etc. These are lithium cobalt oxide particles in which no magnesium is detected.

[0365] Next, in step S14, the lithium cobalt oxide particles are mixed with an aluminum-containing material. It was coated. Specifically, aluminum isopropoxide was dissolved in isopropanol, An isopropanol solution of aluminum isopropoxide was prepared. Then, to this solution, Lithium baltate particles were mixed. Aluminum isopropoxide was mixed with magnesium and fluorine. The mixture was prepared to contain lithium cobalt oxide at a concentration of 0.0917 g / g.

[0366] Then, it was stirred, collected, and dried in the same manner as sample 04.

[0367] Next, in step S15, lithium cobalt oxide coated with a material having aluminum The particles were heated, cooled, and recovered. The procedure was the same as for Sample 04, except that the heating temperature was 500°C. It was made in [year].

[0368] Table 1 shows the preparation conditions for Sample 01 to Sample 06.

[0369] [Table 1]

[0370] [Manufacturing of secondary batteries] Using the positive electrode active materials of Sample 01 to Sample 06 prepared above, CR2032 Tie I fabricated a coin-shaped rechargeable battery (20mm in diameter and 3.2mm in height).

[0371] The positive electrode contains the positive electrode active material (LCO) prepared above, acetylene black (AB), and vinylidene fluoride (PVDF) in LCO:AB:PVDF = 95:3:2 (by weight) A mixture of slurry was used to coat the current collector.

[0372] Lithium metal was used for the counter electrode.

[0373] The electrolyte in the electrolyte solution is 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). C:DEC = 3:7 (volume ratio), with vinylene carbonate (VC) mixed in at 2 wt%. They used something.

[0374] A 25 μm thick polypropylene was used for the separator.

[0375] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0376] [XRD after initial charge] A secondary battery using the positive electrode active materials of Sample 01 to Sample 06 is subjected to CCCV at a predetermined voltage. It was charged. Specifically, it was charged with a constant current of 0.5C until it reached the specified voltage, and then the current value was set to 0.01C. The battery was charged at a constant voltage until it reached this state. Then, the charged secondary battery was placed in a globe box under an argon atmosphere. The positive electrode is disassembled inside the casing, cleaned with DMC (dimethyl carbonate), and the electrolyte is removed. It was removed. Then, analysis was performed using powder XRD with CuKα1 radiation. Then, using the Bruker AXS D8 ADVANCE fully automated multi-purpose X-ray diffractometer... The XRD device was set up for powder samples, but the sample height was crucial for the device. The measurement surface was adjusted to match the required surface. Furthermore, the sample was set up flat, without being curved.

[0377] Figure 27 shows the positive electrode of a secondary battery using the positive electrode active material of Sample 01 after charging at 4.6V. The XRD pattern is shown. For comparison, the same pseudo-spinel type crystal structure and H1-3 type bond as in Figure 3 are shown. The crystal structure pattern is also shown. Sample 01, when charged at 4.6V, shows pseudospeaker activity. A mixture of Nell-type and H1-3-type crystal structures was observed. Furthermore, Rietveld analysis revealed a pseudo It was estimated that the crystal structure contains 66 wt% spinel-type crystals.

[0378] Figure 28 shows secondary batteries using the positive electrode active material of Sample 02 at 4.1V, 4.2V, and 4.3V. The positive terminal X after charging at V, 4.4V, 4.5V, 4.6V, 4.7V, and 4.8V. The RD pattern is shown. Sample 02, when charged at 4.6V, has a pseudo-spinel crystal structure. It was revealed that it has [this characteristic]. Also, sample 02 when charged at 4.7V or higher, It has a different crystal structure from pseudospinel, and its peak width is broadened, resulting in decreased crystallinity. This was speculated.

[0379] Figure 29 shows secondary batteries using the positive electrode active material of Sample 03 at 4.1V, 4.2V, and 4.3V. The positive terminal X after charging at V, 4.4V, 4.5V, 4.6V, 4.7V, and 4.8V. The RD pattern is shown. Sample 03 also exhibits a pseudo-spinel crystal structure when charged at 4.6V. It became clear that... Also, sample 03, which was charged at 4.6V, showed a clearer pattern. This indicates that there are fewer crystalline structures other than pseudo-spinel compared to sample 02, which was charged at 4.6V. It was speculated that... Also, sample 03, when charged at 4.7V or higher, was different from pseudo-spinel. It was inferred that the crystal structure was such that the peak width was broadened and the crystallinity was reduced.

[0380] Figure 30 shows a secondary battery using the positive electrode active material of sample 04 at 4.6V, 4.7V, and The XRD pattern of the positive electrode after charging at 4.8V is shown. Sample 04 is 4.6V and 4 It was revealed that it possesses a pseudo-spinel crystal structure when charged at 0.7V. Also, 4. When charged at 8V, sample 04 has a different crystal structure from pseudospinel, and also peaks. It was inferred that the width had widened and the crystallinity had decreased.

[0381] Figure 31 shows secondary batteries using the positive electrode active material of comparative example sample 05, at 4.1V and 4.2V. After charging at 4.3V, 4.4V, 4.5V, 4.6V, 4.7V, and 4.8V The XRD pattern of the positive electrode is shown. Sample 05, a comparative example, was charged at 4.6V to 4.7V. When this was done, it became clear that it had an H1-3 crystal structure rather than a pseudo-spinel crystal structure. (The peak from 43.5° to 46°(2θ) is particularly characteristic). Also, 4.5V It was revealed that the crystal structure changes to an H1-3 type between 4.8V and 4.6V. When charged, sample 05 had a crystal structure different from both pseudospinel and H1-3, The widening of the peak suggested a decrease in crystallinity.

[0382] Figure 32 shows the secondary battery using the positive electrode active material of comparative example sample 06 after charging at 4.6V. The XRD pattern of the positive electrode is shown. Sample 06, when charged at 4.6V, is of type H1-3. It was revealed that it has a crystalline structure.

[0383] [XRD after multiple charges] Next, for samples 02, 03, and the comparative example sample 05, at 4.6V... The device was analyzed using XRD after multiple charging cycles. Specifically, it was charged at 4.6V using CCCV. The sample was one charge. Furthermore, after CCCV charging at 4.6V, the discharge voltage was... The battery was discharged with a constant current (CC discharge) until it reached 2.5V, and then charged with CCCV at 4.6V. We used a sample that had been charged twice. In some cases, we also prepared a sample that had been charged nine times.

[0384] Figure 33 shows a secondary battery using the positive electrode active material of Sample 02, after being charged once at 4.6V. The XRD pattern of the positive electrode after two charges is also shown. In the first charge, a pseudo-spinel type bond formed. In addition to the crystal structure, H1-3 type crystal structures and other structures are present, resulting in reduced crystallinity. This was speculated. However, in the second charge, structures other than the pseudo-spinel crystal structure decreased, and the first charge It had a higher crystallinity than what was visible in the eye.

[0385] Figure 34 shows a secondary battery using the positive electrode active material of Sample 03, tested once, twice, and at 4.6V. The XRD pattern of the positive electrode after 9 charges is shown. In Sample 03, the first charge was also pseudo In addition to the spinel-type crystal structure, H1-3 type crystal structures and other structures also exist, resulting in reduced crystallinity. It was inferred that this was happening. However, in subsequent charges, structures other than the pseudo-spinel crystal structure were observed. The formation of certain elements decreased, while the pseudo-spinel crystal structure maintained high crystallinity.

[0386] Figure 35 shows a secondary battery using the positive electrode active material of Sample 05, a comparative example, powered at 4.6V for one cycle. And the XRD pattern of the positive electrode after two charges is shown. Sample 05 shows the first and Both the first and second charges exhibited an H1-3 type crystal structure. This also ranged from 43.5° to 46°. The characteristics become clear when we focus on the peaks present up to 2θ).

[0387] [XRD after multiple discharges] Next, samples 02, 03, and the comparative example sample 05 were subjected to 10 doses. After charging, analysis was performed using XRD. Specifically, CCCV charging (4.6V) was performed followed by CC After repeating the charge-discharge cycle (discharging at 2.5V) 10 times, the discharged secondary battery was disassembled and corrected. The poles were extracted and analyzed using XRD.

[0388] Figure 36 shows the results of 10 discharges for Sample 02, Sample 03, and the comparative example Sample 05. The XRD pattern of the positive electrode after the procedure is shown. For comparison, the same LiCoO2(O3) as in Figure 3 is shown, and a pseudo- The patterns of the spinel-type crystal structure and the H1-3-type crystal structure are also shown. Sample 0 2. Sample 03 and Sample 05 all have the structure of LiCoO2(O3). However, in sample 05, the (0 0 3) plane in LiCoO2(O3), (0 The width of the diffraction peaks from planes perpendicular to the c-axis, such as the 0-6 plane, was broadened, indicating a decrease in crystallinity. In contrast, sample 02 and sample 03 show high tensile strength because no shift occurs in the CoO2 layer. It was estimated that it maintained its crystallinity and showed little degradation after 10 charge-discharge cycles.

[0389] [Volume change] Next, we infer the lattice constant and crystal structure from the XRD patterns at each charging depth of sample 03. Then, the volume per unit cell of each crystal structure was determined and compared with the volume before charging. Furthermore, to facilitate comparison with other crystal structures, the c-axis of the H1-3 type crystal structure is defined as a unit. The calculation was performed using half the value of 'Ru'.

[0390] Table 2 shows the lattice constants and crystals inferred from the XRD patterns at each charging depth of Sample 03. Show the structure.

[0391] [Table 2]

[0392] When charged at 4.1V or higher and 4.5V or lower, the two-phase connection belonging to space group R-3m is always It was hypothesized that it would take on a crystalline structure. This is because the charging depth is within or between particles of each positive electrode active material. This was thought to be due to the difference. In Table 2, R-3m(1) and R-3m(2) are denoted as follows. Ta.

[0393] And when charged at 4.6V, the pseudo-spinel crystal structure and the H1-3 type crystal structure are mixed. It was estimated that the pseudo-spinel crystal structure is 77w. It was estimated that it contained more than t%.

[0394] Furthermore, when charged at 4.7V, the H1-3 type crystal structure and the O1 type crystal structure are mixed. It was estimated that this was the case.

[0395] Furthermore, the pseudo-spinel crystal structure has a volume change rate of 2.5% or less from the O3 crystal structure, and is more detailed While the finest example is less than 2.2%, the H1-3 type crystal structure is derived from the O3 type crystal structure. The rate of change in volume was 3.5% or more.

[0396] Figure 37 shows a graph of the volume change rates from Table 2. O3: Marker indicating a charging depth of 0. Refer only to the horizontal axis at the top of the graph. Also, in Figure 37, the crystal structure is R-3m(1)(2) It is estimated to have one of the following crystal structures: pseudo-spinel type crystal structure, H1-3 type crystal structure, or O1 type crystal structure. The items being processed are indicated by individual markers.

[0397] As is clear from Table 2 and Figure 37, the pseudo-spinel crystal structure is more efficient than the H1-3 crystal structure. Also, the volume change per unit cell is small. Furthermore, sample 03, which was charged at 4.6V, Because it contains more than 77 wt% of pseudo-spinel-type crystal structure, changes in crystal structure and volume are suppressed. It became clear that this was the case.

[0398] [Cycle Characteristics] Next, the cycle characteristics of secondary batteries using Sample 01, Sample 03, and Sample 05. I evaluated it.

[0399] Note that samples 01 and 03, whose cycle characteristics were evaluated, were XRD analysis samples. Because the batches are different and the manufacturing conditions are slightly different, an asterisk is added to the graph. There are no significant differences in their characteristics as positive electrode active materials. Specifically, sample 01 is subjected to the first heating... The process was carried out at 1000°C. For sample 03, the amount of TTIP used for sol-gel processing was 0. The concentration was set to 0.1 ml / g, and the second heat treatment was carried out in a dry air atmosphere.

[0400] Coin cells consist of positive electrode active material (LCO), acetylene black (AB), and polyvinyl fluoride. Redene (PVDF) is mixed in a ratio of LCO:AB:PVDF = 95:2.5:2.5 (by weight). The rest of the process was carried out in the same manner.

[0401] The cycle test was performed at 25°C, and charging was done using CCCV (0.5C, 4.6V, cutoff current 0.01%). C) The discharge was set to CC (0.5C, 2.5V). Note that here, 1C is the positive electrode active material. The current value was set to 137 mA / g.

[0402] Figure 38(A) shows the discharge capacities of sample 01, sample 03, and sample 05. B) shows the discharge capacity retention rate. Comparative example sample 05 maintained its discharge capacity after 40 cycles. The rate decreased to 40.9%. On the other hand, the positive electrode active material of one aspect of the present invention had an initial capacity that was lower than that of the comparative example. They were equally high, with sample 03 at 78.4% at 100 cycles and sample 01 at 7 At cycle 0, it showed good cycle characteristics with a rate of 67.5%.

[0403] The positive electrode active material according to one aspect of the present invention exhibits good cycles even when charged and discharged at a high voltage of 4.6V. It became clear that it exhibited certain characteristics.

[0404] Thus, in Samples 01 to 04, which are positive electrode active materials according to one aspect of the present invention, 4 It was revealed that it possesses a pseudo-spinel crystal structure in over 60% of cases when charged at 0.6V. The H1-3 type crystal structure has a smaller difference in crystal structure and volume compared to the discharge state. Therefore, it does not deteriorate easily even after repeated charging and discharging. Therefore, when charged at high voltage, pseudo-spinel If the positive electrode active material has a type crystal structure, it will have good cycle characteristics even when charged and discharged at high voltage. be.

[0405] In contrast, in comparative examples Sample 05 and Sample 06, the pseudo-speed was when charging at 4.6V. It is clear that the Nell-type crystal structure is either absent or present in very small amounts, and that the crystal structure mainly adopts the H1-3 type. This is because the H1-3 type crystal structure differs greatly from the O3 type crystal structure in terms of crystal structure and volume. They are prone to degradation. Therefore, samples 05 and 06 cannot withstand high-voltage charging. It is a material, and in reality, the discharge capacity decreases significantly.

[0406] Note that comparative example sample 05 also contains magnesium and fluorine, similar to sample 01. However, when charged at 4.6V, it mainly adopts an H1-3 type crystal structure, resulting in poor cycle characteristics. As described above, the positive electrode active material of one aspect of the present invention is characterized by minimal change in its crystal structure during charging and discharging. This is a characteristic, and it has been shown that it cannot be determined solely by the elements it contains. [Examples]

[0407] In this example, a positive electrode active material 100 according to one aspect of the present invention and lithium cobalt oxide of a comparative example were prepared. Next, we will explain the results of the analysis using ESR.

[0408] [Fabrication of positive electrode active material] ≪Sample 11A · Sample 11B≫ Sample 1 is the result of adding magnesium and fluorine to the starting material and performing the first heat treatment. Sample 1A was used, and the sample that underwent a second heat treatment afterward was designated as Sample 11B.

[0409] Steps S11 and S12 are the ratio of each element Li 1.02 Co 0.99 Mg 0.01 O 1.98 F 0.02 Lithium carbonate, cobalt oxide, magnesium oxide are used to achieve this. The um and lithium fluoride were weighed and mixed. Then the first heat treatment in step S13 was performed. Next, using an aluminum oxide crucible, the flow rate of the dry air atmosphere is set to 10 L / min, and the holding... The temperature was set to 1000°C (heating rate of 200°C / hour), and the holding time was 10 hours. From the holding temperature to room temperature... The cooling time was set to 10 to 15 hours. The material synthesized by the first heat treatment was Particles of lithium cobalt oxide containing magnesium and fluorine were designated as Sample 11A.

[0410] Next, lithium cobalt oxide particles containing magnesium and fluorine from sample 11A were placed in alumina The mixture was placed in a crucible and subjected to the second heat treatment in step S15. The flow rate of the dry air atmosphere was 10 L. The temperature was set to / min, the holding temperature to 800°C (heating increase of 200°C / hour), and the holding time to 2 hours. The cooling time from the temperature to room temperature was set to between 10 and 15 hours. The resulting particles were designated as Sample 11B.

[0411] ≪Sample 12B≫ As a comparative example, the first and second heat treatments were performed without adding magnesium and fluorine. The sample created using this method was designated as Sample 12B.

[0412] Lithium carbonate and cobalt oxide were weighed out so that the ratio of each element was Li1CO1O2. The rest of the sample was prepared in the same way as sample 11B.

[0413] [ESR] Samples 11A, 11B, and 12B were analyzed using ESR. The results are shown in Figures 39 and 40. Figure 39 shows the signal measured at room temperature. Figure 40 shows the signal at low temperature. (10K) The measurement results are shown in an enlarged diagram for comparison with sharp signals around 320mT. ru.

[0414] As shown in Figure 39, in samples 12B and 11A, the range was from 120mT to 150 A broad signal centered around mT was detected, but in sample 11B this signal was The signal was below the detection limit. This signal is for oxygen 4-coordinate Co (site A in Figure 5). I will comply.

[0415] Therefore, sample 12B, which does not contain magnesium and fluorine, and magnesium Sample 11A, which contains fluorine but does not undergo the second heat treatment, has a spinel-type crystal structure. It has Co3O4, but also has magnesium and fluorine and has undergone a second heat treatment. In sample 11B, the levels were found to be below the detection limit.

[0416] Furthermore, as shown in Figure 40, all samples exhibited a sharp peak centered around approximately 320 mT. It was detected. This signal corresponds to oxygen-6 coordinated Co (site B in Figure 5).

[0417] Of these, in sample 11A in Figure 40(B) and sample 11B in Figure 40(C), 3 A shoulder peak was observed around 12mT, but it was not seen in sample 12B in Figure 40(A). It was not found. This peak indicates the presence of Mg near Co. Furthermore, it has become clear that the presence of Mg in the positive electrode active material can be determined using ESR. . [Examples]

[0418] In this example, what elements, when dissolved in solid solution, result in a pseudo-spinel crystal structure during high-voltage charging? The likelihood of developing it was revealed through calculations.

[0419] As explained in Figure 2, the H1-3 type crystal structure is a CoO2 structure such as P-3m1(O1) It is a structure in which the structure and the structure of LiCoO2, such as R-3m(O3), are alternately layered. ru.

[0420] Therefore, when the number of structures belonging to P-3m1 increases to about half, the crystal structure becomes H1-3 type. It can be considered that it is easy. Conversely, if structures belonging to R-3m account for more than 50%, R It can be considered that it is likely to form a pseudo-spinel type crystal structure with -3m. Therefore, P-3 Using crystal structure models of m1 and R-3m, the positive electrode active material in a high-voltage charging state was reproduced, and Mg, The stabilization energy was calculated for cases containing Al or Ti.

[0421] The crystal structure model in the high-voltage charging state is obtained by subtracting all the Li from R-3m(O3) as explained in Figure 2. The extracted material, P-3m1(O1), and were used. Then, as follows, Mg, Al Alternatively, when Ti is inserted at the most stable position between the CoO2 layers, or when it is replaced at the Co site... The sum was calculated for each.

[0422] Figure 41 shows the crystal structure model of P-3m1 when Mg, Al, or Ti are located between two CoO layers. (A1) shows the crystal structure model of R-3m in Figure 41(A2). Mg, Al or Ti Figure 41(B1) shows the crystal structure model of P-3m1 when it is located at the Co site, and the R-3m site The crystal structure model is shown in Figure 41(B2). The calculation conditions are shown in Table 3.

[0423] [Table 3]

[0424] The energy difference ΔE(eV) between the case of a space group P-3m1 structure and the case of a space group R-3m structure. When inserting Mg between the CoO2 layers, the calculation was performed using the following formula. The energy of the elements was calculated using the energy of the individual atoms.

[0425]

number

[0426] Similarly, when substituting Mg at the Co site, the calculation was performed using the following formula.

[0427]

number

[0428] Figure 42 shows the results of similar calculations performed for other elements. For comparison, inserts or placeholders are shown. The results for the case where no conversion occurred, and the case where Li was inserted between the CoO2 layers, are also shown.

[0429] Figure 42(A) shows the stability when Al, Ti, Mg, or Li is inserted between the CoO2 layers. This is a graph showing the energy of transformation ΔE. For all elements, ΔE is a negative value, and This means that the structure of the space group R-3m is more stable than that of P-3m1. The values ​​for these elements were lower than those for Li. In other words, the positive electrode has these elements between the CoO2 layers. The active material is more likely to form an R-3m structure even under high-voltage charging conditions than simple LiCoO2. It was shown that among Al, Ti, and Mg, Mg was the most effective. It became clear.

[0430] Figure 42(B) shows the stabilization energy when Al, Ti, or Mg is substituted at the Co site. This is a graph showing ΔE. For all elements, ΔE is a positive value, indicating the P-3m1 structure. This showed that it is stable. Al and Ti are more stable than when not substituted (when Co is present). While the values ​​for other substances were low, the Mg value was higher than in the case where substitution was not performed.

[0431] Therefore, while Mg present between the CoO2 layers is highly effective in maintaining the R-3m structure, It was revealed that the Mg present at the Co site has no effect.

[0432] Next, in the case of the R-3m(O3) crystal structure in the discharged state with all lithium inserted, A Calculate whether it is more stable to substitute l, Ti, or Mg at the Li site or the Co site. The calculation method was the same as in Figure 42. The results are shown in Figure 43.

[0433] Whether Al and Ti are substituted at the Li site or the Co site, the ΔE is similarly negative. It took the value of . Also, ΔE was smaller for Ti. Therefore, Al and Ti are Li It was shown that CoO2 tends to be easily soluble, and Ti in particular is more easily soluble.

[0434] On the other hand, when comparing Mg at the Li site and the Co site, the Li site was significantly more stable. Therefore, it was shown that Mg is more likely to enter the Li site than the Co site. Even with this substitution, ΔE is positive, so Mg tends to be somewhat less soluble in LiCoO2. It can be said that, due to this tendency, some Mg segregates in the surface layer and near grain boundaries. This can explain the phenomenon.

[0435] From the above, if Mg is present between the CoO2 layers (Li site), a large amount of Li is extracted, resulting in high It is easy to maintain the R-3m structure even in a voltage-charged state, and it is easy to form a pseudo-spinel crystal structure. This was suggested. Therefore, Mg, which readily enters the Li site of LiCoO2, was subjected to a second heat treatment. It is considered important to ensure that the material is contained in the Li site (not the Co site) during the manufacturing process that includes this step. It can be obtained. [Explanation of Symbols]

[0436] 100 Cathode active material 200 Active material layer 201 Graphene Compounds 211a positive electrode 211b negative electrode 212a Lead 212b Reed 214 Separator 215a Joint 215b Joint 217 Fixing member 250 Secondary battery 251 Exterior 261 Folded section 262 Seal part 263 Seal part 271 Ridge 272 Valley Line 273 Space 300 Secondary battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 secondary battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior 510 Positive lead electrode 511 Negative lead electrode 600 Secondary battery 601 Positive Cap 602 Battery Can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating board 609 Insulating board 611 PTC element 612 Safety valve mechanism 613 Conductive plate 614 Conductive plate 615 modules 616 Conductor 617 Temperature control device 900 Circuit Boards 910 Labels 911 terminal 912 Circuit 913 Secondary battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 920 Display device 921 Sensor 922 terminals 930 cabinets 930a enclosure 930b enclosure 931 negative electrode 932 Positive electrode 933 Separator 950 Wound body 951 terminal 952 terminals 980 Secondary battery 981 film 982 film 993 Wound body 994 negative electrode 995 positive electrode 996 Separator 997 Lead Electrode 998 Lead Electrode 7100 Portable Display Device 7101 enclosure 7102 Display section 7103 Operation Buttons 7104 Secondary battery 7200 Mobile Information Terminal 7201 enclosure 7202 Display section 7203 Band 7204 Buckle 7205 Operation Buttons 7206 Input / output terminal 7207 Icons 7300 display device 7304 Display section 7400 mobile phones 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 7407 Secondary battery 7408 Lead Electrode 7500 e-cigarettes 7501 Atomizer 7502 Cartridge 7504 Secondary battery 8000 display device 8001 enclosure 8002 Display section 8003 Speaker section 8004 Secondary battery 8021 Charging device 8022 Cable 8024 Secondary battery 8025 Secondary battery 8100 Lighting device 8101 enclosure 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 floor 8107 Window 8200 indoor unit 8201 enclosure 8202 Air outlet 8203 Secondary battery 8204 Outdoor unit 8300 Electric Refrigerator / Freezer 8301 enclosure 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 automobiles 8401 Headlight 8406 Electric motor 8500 automobiles 8600 Scooter 8601 Side Mirror 8602 Secondary battery 8603 Turn signal light 8604 Under-seat storage 9600 Tablet devices 9625 Switch 9626 Switch 9627 Switch 9628 Operation switch 9629 Fastener 9630 cabinet 9630a enclosure 9630b enclosure 9631 Display section 9633 Solar Cell 9634 Charge / Discharge Control Circuit 9635 Energy Storage Unit 9636 DC-DC converter 9637 Converter 9640 Moving parts

Claims

1. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. In the range of 19° to 20° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure, and in the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

2. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. Among the diffraction peaks observed in the range of 19° to 20° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is the largest, and among the diffraction peaks observed in the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is the largest. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

3. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. In the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

4. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. Among the diffraction peaks observed in the range of 43.5° to 46° of the aforementioned XRD pattern, the diffraction peak exhibiting the pseudo-spinel crystal structure has the largest maximum intensity. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

5. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, In the EDX radiation analysis of the positive electrode active material, the titanium concentration peak was located in a deeper region than the magnesium concentration peak. When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. In the range of 19° to 20° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure, and in the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

6. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, In the EDX radiation analysis of the positive electrode active material, the titanium concentration peak was located in a deeper region than the magnesium concentration peak. When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. Among the diffraction peaks observed in the range of 19° to 20° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is the largest, and among the diffraction peaks observed in the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is the largest. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

7. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, In the EDX radiation analysis of the positive electrode active material, the titanium concentration peak was located in a deeper region than the magnesium concentration peak. When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. In the range of 43.5° to 46° of the XRD pattern, the maximum intensity of the diffraction peak indicating the pseudo-spinel crystal structure is greater than the maximum intensity of the diffraction peak indicating the H1-3 crystal structure. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

8. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material containing cobalt, oxygen, magnesium, fluorine, and titanium. The positive electrode active material contains lithium cobalt oxide, In the EDX radiation analysis of the positive electrode active material, the titanium concentration peak was located in a deeper region than the magnesium concentration peak. When the positive electrode was subjected to XRD measurement under the following XRD measurement conditions, the XRD pattern due to the CuKα1 line showed diffraction peaks indicating a pseudo-spinel type crystal structure at 2θ = 19.30 ± 0.20° and 2θ = 45.55 ± 0.10°. Among the diffraction peaks observed in the range of 43.5° to 46° of the aforementioned XRD pattern, the diffraction peak exhibiting the pseudo-spinel crystal structure has the largest maximum intensity. Lithium-ion rechargeable battery. XRD measurement conditions: A CR2032 type coin cell is fabricated using the above-mentioned positive electrode, lithium metal as the counter electrode, 1 mol / L lithium hexafluoride phosphate as the electrolyte of the electrolyte solution, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7 and vinylene carbonate (VC) at 2 wt%, polypropylene as the separator, and stainless steel for the positive and negative electrode cans. The fabricated coin cell is charged at a constant current of 0.5C (1C is the current value per positive electrode active material, which is 137 mA / g) to 4.6V in a 25°C environment, then charged at a constant voltage until the current value becomes 0.01C, the coin cell after constant voltage charging is disassembled in an argon atmosphere to remove the positive electrode, the positive electrode is washed with dimethyl carbonate, and then the positive electrode is measured by XRD.

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