Separators and secondary batteries

Abstract

To provide a secondary battery with minimal degradation. To provide a secondary battery with high safety. To provide a separator with excellent properties. To provide a separator that realizes a secondary battery with high safety. To provide a novel separator. [Solution] A separator comprising a polymer porous film and a layer having a ceramic material containing metal oxide fine particles, wherein the thickness of the layer having the ceramic material is 1 μm or more and 100 μm or less, and the thickness of the polymer porous film is 4 μm or more and 50 μm or less.

Description

Technical Field

[0001] The present invention relates to a secondary battery using a separator and a method for manufacturing the same. Alternatively, it relates to a portable information terminal, a vehicle, etc. having a secondary battery.

[0002] One aspect of the present invention relates to an article, 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.

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

[0004] In this specification, the power storage device refers to all elements and devices having a power storage function. For example, it includes power storage devices (also referred to as secondary batteries) such as lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors.

Background Art

[0005] 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 increasing 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, or next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV), and have become indispensable in modern information society as a source of repeatedly rechargeable energy.

[0006] In order to simultaneously improve the thermal, electrochemical safety, and performance of lithium ion secondary batteries, improvement of separators has been studied.

[0007] For example, Patent Document 1 discloses a method for manufacturing an inorganic composite porous separator film having organic and inorganic materials. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2008-524824 [Overview of the project] [Problems that the invention aims to solve]

[0009] One aspect of the present invention aims to provide a secondary battery that undergoes less degradation. Alternatively, one aspect of the present invention aims to provide a secondary battery that is highly safe. Alternatively, one aspect of the present invention aims to provide a separator with excellent properties. Alternatively, one aspect of the present invention aims to provide a separator that realizes a secondary battery that is highly safe. Alternatively, one aspect of the present invention aims to provide a novel separator. Alternatively, one aspect of the present invention aims to provide a method for manufacturing a separator that realizes a secondary battery that is highly safe. Alternatively, one aspect of the present invention aims to provide a novel method for manufacturing a separator.

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. It is possible to extract other problems from the description, drawings, and claims. [Means for solving the problem]

[0011] One aspect of the present invention is a separator comprising a polymer porous film and a layer having a ceramic material containing metal oxide fine particles, wherein the thickness of the layer having the ceramic material is 1 μm or more and 100 μm or less, and the thickness of the polymer porous film is 4 μm or more and 50 μm or less.

[0012] Alternatively, in one aspect of the present invention, the density of the layer having a ceramic material is 0.1 g / cm³ 3 More than 2g / cm 3 The following is a separator.

[0013] Alternatively, one aspect of the present invention is a separator in which the porosity of the polymer porous membrane is 20% by volume or more and 90% by volume or less.

[0014] Alternatively, in one aspect of the present invention, the weight per unit area of ​​the polymer porous film is 4 g / m². 2 More than 20g / m 2 Preferably, 5 g / m 2 More than 12g / m 2 The following is a separator.

[0015] Alternatively, one aspect of the present invention is a separator in which metal oxide fine particles contain one or more of magnesium oxide, aluminum oxide, titanium oxide, silicon oxide, magnesium hydroxide, aluminum hydroxide, and titanium hydroxide.

[0016] Alternatively, one aspect of the present invention is a separator in which metal oxide fine particles contain magnesium hydroxide.

[0017] Alternatively, one aspect of the present invention is a separator in which the average particle size of metal oxide fine particles is 0.01 μm or more and 50 μm or less.

[0018] Alternatively, one aspect of the present invention is a separator in which a layer having a ceramic material is in contact with one surface of a polymer porous film.

[0019] Alternatively, one aspect of the present invention is a separator comprising a polymer porous film and a layer having a plurality of ceramic materials containing metal oxide fine particles, wherein the layer having the plurality of ceramic materials is positioned so as to sandwich the polymer porous film, the thickness of the layer having the ceramic materials is 1 μm or more and 100 μm or less, and the thickness of the polymer porous film is 4 μm or more and 50 μm or less.

[0020] Or, in one aspect of the present invention, a separator has a density of a layer having a ceramic-based material of 0.1 g / cm 3 or more and 2 g / cm 3 or less.

[0021] Or, in one aspect of the present invention, a separator has a porosity of a polymer porous membrane of 20% by volume or more and 90% by volume or less.

[0022] Or, in one aspect of the present invention, a weight per unit area of a polymer porous membrane is 4 g / m 2 or more and 20 g / m 2 or less, preferably 5 g / m 2 or more and 12 g / m 2 or less.

[0023] Or, in one aspect of the present invention, a separator contains one or more of magnesium oxide, aluminum oxide, titanium oxide, silicon oxide, magnesium hydroxide, aluminum hydroxide, and titanium hydroxide in metal oxide fine particles.

[0024] Or, in one aspect of the present invention, a separator contains magnesium hydroxide in metal oxide fine particles.

[0025] Or, in one aspect of the present invention, a separator has an average particle diameter of metal oxide fine particles of 0.01 μm or more and 50 μm or less.

[0026] Or, in one aspect of the present invention, a separator has a layer having a ceramic-based material in contact with one surface of a polymer porous membrane.

[0027] Or, in one aspect of the present invention, a secondary battery has a positive electrode, a negative electrode, the separator described above sandwiched between the positive electrode and the negative electrode, and an electrolyte.

[0028] Also, in the above configuration, it is preferable that an electrolyte is disposed inside pores of the polymer porous membrane.

[0029] Alternatively, one aspect of the present invention is a method for producing a separator, comprising: a first step of mixing a ceramic material containing metal oxide fine particles with a first solvent to produce a first mixture; a second step of mixing the first mixture, a first binder, and a second solvent to produce a second mixture; a third step of mixing the second mixture, a second binder, and a third solvent to produce a third mixture; a fourth step of coating the third mixture onto a polymer porous film; and a fifth step of heating the polymer porous film coated with the third mixture at a temperature of 60°C to 300°C to dry it.

[0030] In the fifth step described above, it is more preferable to heat and dry the polymer porous film coated with the third mixture at a temperature of 60°C to 200°C.

[0031] The porosity of a polymer porous membrane refers to the proportion of the volume occupied by pores in the polymer porous membrane. Similarly, the porosity of a layer containing a ceramic material refers to the proportion of the volume occupied by pores in the layer containing the ceramic material. Density can be determined from thickness, weight, and area.

[0032] The porosity of the layer containing the ceramic material is, for example, 50 volume percent or more. [Effects of the Invention]

[0033] According to one aspect of the present invention, a secondary battery with less degradation can be provided. Furthermore, according to one aspect of the present invention, a secondary battery with high safety can be provided. Furthermore, according to one aspect of the present invention, a separator with excellent properties can be provided. Furthermore, according to one aspect of the present invention, a separator that realizes a secondary battery with high safety can be provided. Furthermore, according to one aspect of the present invention, a novel separator can be provided. Furthermore, according to one aspect of the present invention, a method for manufacturing a separator that realizes a secondary battery with high safety can be provided. Furthermore, according to one aspect of the present invention, a method for manufacturing a novel separator can be provided.

[0034] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0035] [Figure 1] Figures 1A to 1D are examples of cross-sectional views of a secondary battery. [Figure 2] Figures 2A to 2D are examples of cross-sectional views of a secondary battery. [Figure 3] Figure 3 is a flowchart showing an example of a method for fabricating a separator coated with a ceramic material. [Figure 4] Figure 4 shows the method for preparing the material. [Figure 5] Figure 5 is an example of a cross-sectional view showing one aspect of the present invention. [Figure 6] Figure 6 illustrates the crystal structure of the positive electrode active material. [Figure 7] Figure 7 illustrates the crystal structure of the positive electrode active material. [Figure 8] Figures 8A and 8B show examples of the external appearance of a secondary battery. [Figure 9] Figures 9A and 9B illustrate the method for manufacturing a secondary battery. [Figure 10] Figures 10A and 10B illustrate the method for manufacturing a secondary battery. [Figure 11] Figure 11 shows an example of the appearance of a secondary battery. [Figure 12] Figure 12 is a top view showing an example of a secondary battery manufacturing apparatus. [Figure 13] Figure 13 is a cross-sectional view showing an example of a method for manufacturing a secondary battery. [Figure 14] Figures 14A to 14C are perspective views showing an example of a method for manufacturing a secondary battery. Figure 14D is a cross-sectional view corresponding to Figure 14C. [Figure 15] Figures 15A to 15F are perspective views showing an example of a method for manufacturing a secondary battery. [Figure 16] Figure 16 is a cross-sectional view showing an example of a secondary battery. [Figure 17] Figure 17A shows an example of a secondary battery. Figures 17B and 17C show an example of a method for fabricating a laminate. [Figure 18] Figures 18A to 18C show an example of a method for manufacturing a secondary battery. [Figure 19] Figures 19A and 19B are cross-sectional views showing an example of a laminate. Figure 19C is a cross-sectional view showing an example of a secondary battery. [Figure 20] Figures 20A and 20B show an example of a secondary battery. Figure 20C shows the inside of a secondary battery. [Figure 21] Figures 21A to 21C show examples of secondary batteries. [Figure 22] Figure 22A is a perspective view showing an example of a battery pack. Figure 22B is a block diagram showing an example of a battery pack. Figure 22C is a block diagram showing an example of a vehicle with a motor. [Figure 23] Figures 23A to 23E show examples of transport vehicles. [Figure 24] Figure 24A shows an electric bicycle, Figure 24B shows the secondary battery of an electric bicycle, and Figure 24C is a diagram illustrating an electric motorcycle. [Figure 25] Figures 25A and 25B show an example of an energy storage device. [Figure 26] Figures 26A to 26E show examples of electronic devices. [Figure 27] Figures 27A to 27H illustrate an example of an electronic device. [Figure 28] Figures 28A to 28C illustrate an example of an electronic device. [Figure 29] Figure 29 illustrates an example of an electronic device. [Figure 30] Figures 30A to 30C illustrate an example of an electronic device. [Figure 31] Figures 31A to 31C show examples of electronic devices. [Figure 32] Figure 32 shows the results of measuring the cobalt solution concentration by atomic absorption spectrometry. [Modes for carrying out the invention]

[0036] Embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and its form and details can be modified in various ways. Furthermore, the present invention is not to be interpreted as being limited to the embodiments described below.

[0037] Furthermore, in this specification, crystal planes and directions are indicated by Miller indices. In crystallography, crystal planes and directions are indicated by a superscript bar above the number, but in this specification, due to limitations in patent application notation, a minus sign (-) may be placed before the number instead of a bar above it. In addition, individual orientations indicating directions within a crystal are indicated by [ ], collective orientations indicating all equivalent directions are indicated by < >, individual planes indicating crystal planes are indicated by ( ), and collective planes having equivalent symmetry are indicated by {}.

[0038] In this specification, the surface layer of particles such as active material is preferably a region within 50 nm from the surface, more preferably within 35 nm, and even more preferably within 20 nm. Surfaces formed by cracks or fissures may also be considered the surface. The region deeper than the surface layer is referred to as the interior.

[0039] In this specification, the layered rock salt crystal structure of a composite oxide containing lithium and a transition metal refers to a crystal structure having a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and in which the transition metal and lithium are regularly arranged to form a two-dimensional plane, thereby enabling two-dimensional diffusion of lithium. Defects such as vacancies in cations or anions may be present. Furthermore, strictly speaking, a layered rock salt crystal structure may have a distorted lattice structure of the rock salt crystal.

[0040] In this specification, a rock salt-type crystal structure refers to a structure in which cations and anions are arranged alternately. However, deficiencies in cations or anions are acceptable.

[0041] Furthermore, in this specification, the O3' type crystal structure of a composite oxide containing lithium and a transition metal refers to a crystal structure with a space group R-3m, which is not a spinel type crystal structure, but in which ions such as cobalt and magnesium occupy the oxygen 6-coordinate positions, and the arrangement of cations has a symmetry similar to that of the spinel type. Note that in the O3' type crystal structure, light elements such as lithium may occupy the oxygen 4-coordinate positions, and in this case as well, the arrangement of ions has a symmetry similar to that of the spinel type.

[0042] Furthermore, the O3' type crystal structure can be described as a crystal structure similar to the CdCl2 type crystal structure, although it has Li randomly placed between layers. This crystal structure similar to the CdCl2 type is formed when lithium nickelate is replaced with Li 0.06 This crystal structure is similar to that of NiO2 when charged to this level, but it is known that pure lithium cobalt oxide or layered rock salt-type cathode active materials containing a large amount of cobalt do not usually adopt this crystal structure.

[0043] The anions in layered rock salt crystals and rock salt crystals adopt a cubic close-packed structure (face-centered cubic lattice structure). It is also presumed that the anions in O3'-type crystals adopt a cubic close-packed structure. When these are in 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 O3'-type crystals is R-3m, which is different from the space group of rock salt crystals Fm-3m (the space group of a typical rock salt crystal) and Fd-3m (the space group of a rock salt crystal with the simplest symmetry). Therefore, the Miller indices of the crystal planes that satisfy the above conditions are different for layered rock salt crystals and O3'-type crystals and for rock salt crystals. In this specification, when the orientation of the cubic close-packed structure composed of anions is aligned in layered rock salt crystals, O3'-type crystals, and rock salt crystals, it is sometimes said that the crystal orientation is approximately the same.

[0044] The general agreement of crystal orientation between two regions can be determined from TEM (transmission electron microscope) images, STEM (scanning transmission electron microscope) images, HAADF-STEM (high-angle scattering annular dark-field scanning transmission electron microscope) images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used as a basis for determination. In STEM images, etc., the arrangement of cations and anions can be observed as a repetition of bright and dark lines. When the orientation of the cubic close-packed structure is aligned in layered rock salt crystals and rock salt crystals, it can be observed that the angle between the repetition of bright and dark lines between crystals is ±5 degrees or less, more preferably ±2.5 degrees or less. Note that light elements such as oxygen and fluorine may not be clearly visible in TEM images, etc., but in such cases, the agreement of orientation can be determined from the arrangement of metallic elements.

[0045] Furthermore, in this specification, the theoretical capacity of the positive electrode active material refers to the amount of electricity when all of the insertable and detachable lithium present in the positive electrode active material has been detached. For example, the theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 274 mAh / g, and the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0046] Furthermore, the extent to which insertable and detachable lithium remains in the positive electrode active material is determined by x in the composition formula, for example, Li x x in CoO2, or Li xThis is denoted by x in MO2 (where M is a transition metal). x can also be said to be the Li occupancy rate of the lithium site. When lithium cobalt oxide satisfies the stoichiometric ratio, it is LiCoO2 and the Li occupancy rate of the lithium site is x=1. Similarly, a secondary battery that has finished discharging is also LiCoO2, and it can be said that x≈1. Discharge has finished here, for example, when the voltage drops below 2.5V (vs. counter electrode Li) with a current of 100mA / g. In lithium-ion secondary batteries, when the lithium occupancy rate of the lithium site becomes x=1 and no more lithium can be added, the voltage drops sharply. At this point, discharge can be said to have finished. Generally, in lithium-ion secondary batteries using LiCoO2, the discharge voltage drops sharply before reaching 2.5V, so discharge is considered to have finished under the above conditions.

[0047] Furthermore, in this specification, a non-equilibrium phase change refers to a phenomenon that causes a nonlinear change in a physical quantity. For example, a non-equilibrium phase change is thought to occur around the peak in the dQ / dV curve obtained by differentiating capacitance (Q) with respect to voltage (V) (dQ / dV), indicating a significant change in the crystal structure.

[0048] A secondary battery has, for example, a positive electrode and a negative electrode. The positive electrode is composed of a positive electrode active material. The positive electrode active material is, for example, a substance that performs a reaction that contributes to the charge and discharge capacity. However, the positive electrode active material may also contain a portion of substances that do not contribute to the charge and discharge capacity.

[0049] In this specification, the positive electrode active material of one aspect of the present invention may be expressed as a positive electrode material, a positive electrode material for secondary batteries, etc. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a compound. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a composition. In this specification, it is preferable that the positive electrode active material of one aspect of the present invention has a composite.

[0050] The discharge rate is the relative ratio of the discharge current to the battery capacity, and is expressed in units of C. For a battery with a rated capacity of X (Ah), the current equivalent to 1C is X (A). If the battery is discharged with a current of 2X (A), it is said to have been discharged at 2C, and if it is discharged with a current of X / 5 (A), it is said to have been discharged at 0.2C. Similarly, the charge rate is also expressed in the same way: if the battery is charged with a current of 2X (A), it is said to have been charged at 2C, and if it is charged with a current of X / 5 (A), it is said to have been charged at 0.2C.

[0051] Constant current charging refers to a method of charging while maintaining a constant charging rate. Constant voltage charging refers to a method of charging while maintaining a constant voltage once the upper voltage limit is reached. Constant current discharging refers to a method of discharging while maintaining a constant discharge rate.

[0052] (Embodiment 1) In this embodiment, an example of a secondary battery according to one aspect of the present invention will be described using Figure 1. The secondary battery has an outer casing (not shown), a positive electrode 503, a negative electrode 506, a separator 507, and an electrolyte 508 in which a lithium salt or the like is dissolved. The separator 507 is provided between the positive electrode 503 and the negative electrode 506.

[0053] As shown in Figure 1A, the positive electrode 503 has a positive electrode active material layer 502 and a positive electrode current collector 501, and the positive electrode active material layer 502 has a positive electrode active material 561, a conductive additive, and a binder. Figure 1B is an enlarged view of region 502a of the positive electrode active material layer 502, showing an example in which acetylene black 553 and graphene 554 are used as conductive additives. Further details of the positive electrode will be described later.

[0054] Furthermore, the negative electrode 506 has a negative electrode active material layer 505 and a negative electrode current collector 504. The negative electrode active material layer 505 also has a negative electrode active material 563, a conductive additive, and a binder (not shown). Figure 1D is an enlarged view of region 505a of the negative electrode active material layer 505, showing an example in which acetylene black 556 and graphene 557 are used as conductive additives. Details of the negative electrode will be described later.

[0055] As a binder, it is preferable to use rubber materials such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, or ethylene-propylene-diene copolymer. Fluororubber can also be used as a binder.

[0056] Furthermore, it is preferable to use a water-soluble polymer as the binder. Examples of water-soluble polymers include polysaccharides. Examples of polysaccharides include cellulose derivatives such as carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose, diacetylcellulose, and regenerated cellulose, as well as starch. It is even more preferable to use these water-soluble polymers in combination with the aforementioned rubber material.

[0057] Alternatively, it is preferable to use materials such as polystyrene, methyl polyacrylate, polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, or nitrocellulose as the binder.

[0058] You may use a combination of several of the binders mentioned above.

[0059] For example, a material with particularly excellent viscosity-modifying properties may be used in combination with other materials. For instance, rubber materials have excellent adhesive and elastic properties, but their viscosity can be difficult to adjust when mixed with a solvent. In such cases, it is preferable to mix a material with particularly excellent viscosity-modifying properties with a rubber material. As a material with particularly excellent viscosity-modifying properties, for example, a water-soluble polymer can be used. As a water-soluble polymer with particularly excellent viscosity-modifying properties, the aforementioned polysaccharides, such as carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose, and diacetylcellulose, cellulose derivatives such as regenerated cellulose, and starch can be used.

[0060] Furthermore, cellulose derivatives such as carboxymethylcellulose can be made more effective as viscosity modifiers by increasing their solubility, for example, by using salts such as sodium or ammonium salts of carboxymethylcellulose. Increased solubility also improves the dispersibility of the active material and other components when preparing electrode slurries. In this specification, cellulose and cellulose derivatives used as electrode binders include their salts.

[0061] Water-soluble polymers, due to their functional groups, readily adsorb stably onto surfaces such as active materials. When water-soluble polymers adsorb onto the surface of active materials, the particles of the active materials repel each other electrostatically, allowing for stable dispersion of the active materials. Furthermore, cellulose derivatives such as carboxymethylcellulose often contain functional groups such as hydroxyl and carboxyl groups. Because of these functional groups, the polymers interact with each other and may broadly cover the surface of the active material, which is expected to suppress excessive electrolyte decomposition.

[0062] When a binder covers or is in contact with the surface of the active material, it is expected to act as a passivation film, suppressing the decomposition of the electrolyte. For example, if a passivation film is formed on the surface of the active material, the decomposition of the electrolyte can be suppressed at the battery reaction potential. Furthermore, it is even more desirable that the passivation film suppresses electrical conductivity while allowing lithium ions to conduct.

[0063] The active material layer can be prepared by mixing the active material, binder, conductive additive, and solvent to create a slurry, forming the slurry on a current collector, and then volatilizing the solvent.

[0064] The solvent used in the slurry is preferably a polar solvent. For example, one or more of the following can be used: water, methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0065] As the positive electrode current collector 501 and the negative electrode current collector 504, materials with high conductivity that do not alloy with carrier ions such as lithium can be used, such as metals such as stainless steel, gold, platinum, zinc, iron, copper, aluminum, and titanium, and alloys thereof. Aluminum alloys with added elements that improve heat resistance, such as silicon, titanium, neodymium, scandium, and molybdenum, can also be used. Furthermore, they may be formed from metallic elements that react with silicon to form silicides. Examples of metallic elements that react with silicon to form silicides include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, and nickel. The current collector can be in various shapes, such as sheet, mesh, perforated metal, or expanded metal. The current collector should preferably have a thickness of 10 μm to 30 μm.

[0066] Furthermore, it is preferable to use a material for the negative electrode current collector 504 that does not alloy with carrier ions such as lithium.

[0067] As a current collector, a titanium compound may be provided by laminating it on the above-described metal element. As the titanium compound, for example, titanium nitride, titanium oxide, titanium nitride in which part of nitrogen is substituted by oxygen, titanium oxide in which part of oxygen is substituted by nitrogen, and titanium oxynitride (TiO x N y , 0 < x < 2, 0 < y < 1) can be selected singly, or two or more of them can be mixed or laminated and used. Among them, titanium nitride is particularly preferable because it has high conductivity and a high function of suppressing oxidation. By providing a titanium compound on the surface of the current collector, for example, the reaction between the material of the active material layer formed on the current collector and the metal can be suppressed. When the active material layer contains a compound having oxygen, the oxidation reaction between the metal element and oxygen can be suppressed. For example, when aluminum is used as the current collector and the active material layer is formed using graphene oxide described later, there may be a concern about the oxidation reaction between the oxygen in graphene oxide and aluminum. In such a case, by providing a titanium compound on aluminum, the oxidation reaction between the current collector and graphene oxide can be suppressed.

[0068] Also, as graphene 554 and graphene 557, graphene or a graphene compound can be used.

[0069] In this specification and the like, the graphene compound includes multilayer graphene, multi-graphene, graphene oxide, multilayer graphene oxide, multi-graphene oxide, reduced graphene oxide, reduced multilayer graphene oxide, reduced multi-graphene oxide, graphene quantum dots, and the like. The graphene compound refers to a compound having carbon, having a flat plate shape, a sheet shape, etc., and having a two-dimensional structure formed by carbon six-membered rings. The two-dimensional structure formed by the carbon six-membered rings may be referred to as a carbon sheet. The graphene compound may have a functional group. Also, the graphene compound preferably has a bent shape. Also, the graphene compound may be rounded like a carbon nanofiber.

[0070] In one embodiment of the present invention, graphene or a graphene compound can function as a conductive agent in the positive or negative electrode. Multiple graphenes or graphene compounds can form three-dimensional conductive paths within the positive or negative electrode, thereby increasing the conductivity of the positive or negative electrode. Furthermore, since graphene or graphene compounds can adhere to particles within the positive or negative electrode, they can suppress particle collapse within the positive or negative electrode, thereby increasing the strength of the positive or negative electrode. Because graphene or graphene compounds have a thin, sheet-like shape, they can form excellent conductive paths even when occupying a small volume within the positive or negative electrode, thus increasing the volume of active material within the positive or negative electrode and increasing the capacity of the secondary battery.

[0071] [Separator] The separator 507 can be made of, for example, paper, nonwoven fabric, glass fiber, ceramics, etc. Alternatively, it can be made of nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, acrylic, polyolefin, polyurethane, polypropylene, polyethylene, etc. It is preferable that the separator be processed into an envelope shape and arranged to enclose either the positive or negative electrode.

[0072] Furthermore, a polymer film, such as polypropylene or polyethylene, can be used for the separator 507.

[0073] Polymer films containing polypropylene, polyethylene, etc., can be manufactured by dry or wet methods. The dry method involves stretching a polymer film containing polypropylene, polyethylene, etc., while heating it, creating gaps between crystals and forming fine pores. The wet method involves mixing a solvent into the resin beforehand, forming it into a film, and then extracting the solvent to create pores.

[0074] Figure 1C1 shows an enlarged view of region 507a as an example of separator 507 (fabricated by a wet process). In this example, a structure with multiple pores 582 in the polymer film 581 is shown. Figure 1C2 shows an enlarged view of region 507b as another example of separator 507 (fabricated by a dry process). In this example, a structure with multiple pores 585 in the polymer film 584 is shown.

[0075] The diameter of the pores in the separator may differ between the surface layer on the positive electrode side and the surface layer on the negative electrode side. In this specification, the surface layer of the separator is preferably, for example, an area within 5 μm, more preferably within 3 μm, from the surface.

[0076] The separator may have a multilayer structure. For example, a structure in which two types of polymer materials are layered may be used.

[0077] Furthermore, a structure can be used in which a polymer film, such as polypropylene or polyethylene, is coated with a ceramic material, a fluorine-based material, a polyamide-based material, or a mixture thereof.

[0078] As ceramic materials, metal oxides or hydroxides can be used. Examples of metal oxides or hydroxides that can be used include magnesium oxide, titanium oxide, aluminum oxide, silicon oxide, magnesium hydroxide, aluminum hydroxide, and titanium hydroxide. For titanium oxide, both rutile-type and anatase-type materials can be used, but anatase-type materials may be more preferred. The metal oxides that can be used as ceramic materials may also be fine particles.

[0079] For coating polymer films with ceramic-based materials, for example, particle coating or thin film coating can be employed.

[0080] Examples of fluorine-based materials that can be used include PVdF and polytetrafluoroethylene.

[0081] Examples of polyamide materials that can be used include nylon and aramid (meta-aramid, para-aramid).

[0082] Coating the polymer film with a ceramic-based material improves oxidation resistance, thereby suppressing separator degradation during high-voltage charging and discharging and improving the reliability of the secondary battery. Furthermore, coating the polymer film with a fluorine-based material facilitates better adhesion between the separator and electrodes, improving output characteristics. Coating the polymer film with a polyamide-based material, particularly aramid, improves heat resistance, thereby enhancing the safety of the secondary battery.

[0083] Furthermore, to increase the amount of cobalt adsorbed, it is advisable to increase the surface area of ​​the ceramic material. Materials with a layered crystalline structure, such as Mg(OH)2, tend to form flat, thin particles. By forming a layer of ceramic material using such particles, the amount of cobalt adsorbed can be increased. The specific surface area of ​​the ceramic material is, for example, 10 m². 2 It is preferable that the amount is 1 / g or more. The specific surface area can be measured by gas adsorption or the like.

[0084] For example, both sides of a polypropylene film may be coated with a mixed material of one or more ceramic materials selected from magnesium hydroxide and titanium oxide and a binder such as PVdF. Alternatively, the surface of the polypropylene film that contacts the positive electrode may be coated with a mixed material of one or more ceramic materials selected from magnesium hydroxide and titanium oxide and a binder such as PVdF, and the surface that contacts the negative electrode may be coated with a fluorine-based material.

[0085] Figure 2A shows a separator 507 having a polymer porous membrane 521 and a layer 522 having a ceramic material coated on the polymer porous membrane 521. The polymer porous membrane 521 is made of a membrane similar to the porous polymer membrane 581 shown in Figure 1C1. Figure 2C1 shows an enlarged view of region 521a as an example of the polymer porous membrane 521 of the separator 507. In this example, a structure similar to region 507a of the separator 507 shown in Figure 1C1 is shown. Figure 2C2 shows an enlarged view of region 521b as another example of the polymer porous membrane 521 of the separator 507. In this example, a structure similar to region 507b of the separator 507 shown in Figure 1C2 is shown.

[0086] By using a multi-layered separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin, thus increasing the capacity per unit volume of the secondary battery.

[0087] Furthermore, ionic liquids are flame-retardant. By using an ionic liquid as the electrolyte and impregnating the separator with the ionic liquid, it is possible to create a secondary battery that is less prone to flammability.

[0088] The following describes the method for fabricating a separator coated with a ceramic material, using Figure 3 as an example.

[0089] First, a slurry of ceramic material to coat the separator is prepared. The slurry can be prepared, for example, by mixing the ceramic material with a solvent and a binder. At this time, mixing may be carried out in a highly viscous state. Mixing materials in a highly viscous state is sometimes called kneading. As the binder, the binder described in the preparation of the active material layer can be used.

[0090] In step S21, a ceramic material and a solvent are prepared. Multiple ceramic materials may be used in combination. As the solvent, one or more of the following can be used: N-methylpyrrolidone (NMP), water, methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0091] Mixing can be done using a kneader. For example, a rotary-orbit mixer can be used as a kneader.

[0092] In step S22, the ceramic material and solvent prepared in step S21 are kneaded together, and in step S23, a mixture is obtained. It is preferable to first knead the ceramic material and solvent together in order to disperse the ceramic material.

[0093] In step S24, the binder and solvent are added to the mixture obtained in step S23, and in step S25, they are kneaded together, resulting in a mixture in step S26. It is preferable to add the binder little by little to prevent aggregation. In step S25, for example, it is preferable to knead the mixture obtained in step S23, the binder, and the solvent as a mixture with a solid content ratio of 50% to 80%, as this allows for mixing at high viscosity. The solid content ratio refers to the proportion of solids (in this case, ceramic material and binder) in the mixture. Subsequently, in step S27, the binder and solvent are added to the mixture obtained in step S26, and in step S28, they are kneaded together, resulting in a slurry in step S29. It is preferable that the solid content ratio of the prepared slurry is 30%.

[0094] In step S30, the prepared slurry is applied onto the polymer material. A blade method, printing method, or other methods may be used for application. Alternatively, a continuous coating machine may be used. In step S31, the polymer material coated with the slurry can be obtained.

[0095] In step S32, the solvent is evaporated from the slurry applied on the polymer material using a method such as ventilation drying or vacuum drying. The solvent may be evaporated, for example, using warm air or hot air at a temperature of 30°C or higher and 160°C or lower. The atmosphere is not particularly limited.

[0096] Through the above steps, in step S33, a separator coated with a ceramic-based material can be produced.

[0097] 〔Positive Electrode〕 Next, the positive electrode will be described.

[0098] <Positive Electrode Active Material> Examples of the positive electrode active material include composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure. For example, compounds such as LiFePO4, LiFeO2, LiNiO2, LiMn2O4, V2O5, Cr2O5, and MnO2 can be mentioned.

[0099] In addition, it is preferable to mix a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn2O4 as the positive electrode active material with lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (0 < x < 1) (M = Co, Al, etc.)). By adopting such a configuration, the characteristics of the secondary battery can be improved.

[0100] In addition, as the positive electrode active material, the composition formula Li a Mn b M c O dA lithium manganese composite oxide can be used, which can be represented as follows. Here, metal M is preferably a metal element selected from lithium and manganese, or silicon or phosphorus, and more preferably nickel. When measuring the entire particle of lithium manganese composite oxide, <a / (b+c)<2、かつc>it is preferable that the discharge is 0 0 and 0.26 ≤ (b+c) / d < 0.5. The composition of metal, silicon, phosphorus, etc., of the entire particle of lithium manganese composite oxide can be measured, for example, using ICP-MS (inductively coupled plasma mass spectrometer). The oxygen composition of the entire particle of lithium manganese composite oxide can be measured, for example, using EDX. It can also be determined by using molten gas analysis and valence evaluation of XAFS (X-ray absorption fine structure) analysis in combination with ICPMS analysis. A lithium manganese composite oxide refers to an oxide containing at least lithium and manganese, and may contain at least one element selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus.

[0101] Generally, as the positive electrode active material undergoes repeated charging and discharging, a side reaction occurs in which transition metals such as cobalt dissolve into the electrolyte. Furthermore, cobalt ions dissolved from the positive electrode active material adhere to the negative electrode surface, causing cobalt deposition and thickening of the coating on the negative electrode surface. However, since the separator according to one aspect of the present invention is thought to be able to adsorb cobalt, it is expected that the concentration of cobalt dissolved in the electrolyte can be reduced. Therefore, the thickening of the coating on the negative electrode surface can be suppressed, thereby inhibiting the degradation of the secondary battery.

[0102] <Example of a method for producing cobalt-containing materials> ​Next, using Figure 4, an example of a method for producing LiMO2, which is one embodiment of a material applicable as a positive electrode active material, will be described. As metal M, at least one of manganese, cobalt, and nickel can be used. In addition to the metals listed above, metal M may also contain metal X. Furthermore, there are no particular limitations on the substitution position of metal M. In the following description, a cobalt-containing material in which metal X is Mg will be used as an example. Note that the positive electrode active material of one embodiment of the present invention has a crystalline structure of a lithium composite oxide represented as LiMO2, but its composition is not limited to Li:M:O=1:1:2.

[0103] First, in step S11, a composite oxide having lithium, a transition metal, and oxygen is used as the composite oxide 801. Here, it is preferable to use one or more transition metals including cobalt.

[0104] A composite oxide containing lithium, a transition metal, and oxygen can be synthesized by heating a lithium source and a transition metal source in an oxygen atmosphere. As the transition metal source, it is preferable to use a metal that can form a layered rock salt-type composite oxide belonging to space group R-3m together with lithium. For example, at least one of manganese, cobalt, and nickel can be used. In addition to these transition metals, aluminum may also be used. That is, a cobalt source alone may be used as the transition metal source, a nickel source alone may be used, two types of sources (cobalt and manganese), two types of sources (cobalt and nickel), or three types of sources (cobalt, manganese, and nickel). Furthermore, an aluminum source may also be used in addition to these metal sources. The heating temperature at this time is preferably higher than that of step S17, which will be described later. For example, it can be done at 1000°C. This heating process is sometimes called calcination.

[0105] When using a pre-synthesized composite oxide containing lithium, a transition metal, and oxygen, it is preferable to use one with low impurity content. In this specification, the main components of the composite oxide containing lithium, a transition metal, and oxygen, cobalt-containing material, and positive electrode active material are defined as lithium, cobalt, nickel, manganese, aluminum, and oxygen, with elements other than the main components being considered impurities. For example, when analyzed by glow discharge mass spectrometry (GD-MS), the combined impurity concentration is preferably 10,000 ppmw (parts per million weight) or less, and more preferably 5,000 ppmw or less. In particular, the combined impurity concentration of transition metals such as titanium and arsenic is preferably 3,000 ppmw or less, and more preferably 1,500 ppmw or less.

[0106] For example, lithium cobalt oxide particles manufactured by Nippon Chemical Industrial Co., Ltd. (product name: Cellseed C-10N) can be used as pre-synthesized lithium cobalt oxide. This lithium cobalt oxide has an average particle size (D50) of approximately 12 μm, and impurity analysis by glow discharge mass spectrometry shows that the magnesium and fluorine concentrations are 50 ppmw or less, the calcium, aluminum, and silicon concentrations are 100 ppmw or less, the nickel concentration is 150 ppmw or less, the sulfur concentration is 500 ppmw or less, the arsenic concentration is 1100 ppmw or less, and the concentrations of other elements other than lithium, cobalt, and oxygen are 150 ppmw or less.

[0107] The composite oxide 801 in step S11 preferably has a layered rock salt-type crystalline structure with few defects and strains. Therefore, it is preferable that the composite oxide has few impurities. If a composite oxide containing lithium, a transition metal, and oxygen contains many impurities, it is highly likely to have a crystalline structure with many defects or strains.

[0108] In step S12, fluoride 802 is prepared. Suitable fluorides include lithium fluoride (LiF), magnesium fluoride (MgF2), aluminum fluoride (AlF3), titanium fluoride (TiF4), cobalt fluoride (CoF2, CoF3), nickel fluoride (NiF2), zirconium fluoride (ZrF4), vanadium fluoride (VF5), manganese fluoride, iron fluoride, chromium fluoride, niobium fluoride, zinc fluoride (ZnF2), calcium fluoride (CaF2), sodium fluoride (NaF), potassium fluoride (KF), barium fluoride (BaF2), cerium fluoride (CeF2), lanthanum fluoride (LaF3), sodium aluminum hexafluoride (Na3AlF6), etc. Any fluoride 802 that functions as a fluorine source is acceptable. Therefore, instead of fluoride 802, or as part thereof, for example, fluorine (F2), carbon fluoride, sulfur fluoride, oxygen fluoride (OF2, O2F2, O3F2, O4F2, O2F), etc. may be used and mixed into the atmosphere during the heating process described later.

[0109] If fluoride 802 is a compound containing metal X, it can also be used as compound 803 (a compound containing metal X), which will be described later.

[0110] In this embodiment, lithium fluoride (LiF) is used as fluoride 802. LiF is preferred because it has cations in common with LiCoO2. Furthermore, LiF is preferred because it has a relatively low melting point of 848°C and is easily melted in the annealing process described later.

[0111] Furthermore, when LiF is used as fluoride 802, it is preferable to prepare compound 803 (a compound containing metal X) in addition to fluoride 802 as step S13. Compound 803 is a compound containing metal X.

[0112] Furthermore, in step S13, compound 803 is prepared. As compound 803, a fluoride, oxide, hydroxide, etc. of metal X can be used, and the use of a fluoride is particularly preferred.

[0113] When magnesium is used as metal X, MgF2 or the like can be used as compound 803. Magnesium can be distributed at high concentrations near the surface of cobalt-containing materials.

[0114] In addition to fluoride 802 and compound 803, a material containing a metal other than cobalt and metal X may also be mixed. Examples of materials containing a metal other than cobalt and metal X include nickel sources, manganese sources, aluminum sources, iron sources, vanadium sources, chromium sources, niobium sources, titanium sources, etc. It is preferable to pulverize the hydroxides, fluorides, oxides, etc. of each metal and mix them. Pulverization can be carried out, for example, by a wet process.

[0115] Furthermore, the order of steps S11, S12, and S13 may be freely rearranged.

[0116] Next, in step S14, the materials prepared in steps S11, S12, and S13 are mixed and pulverized. Mixing can be done dry or wet, but wet mixing is preferred because it allows for finer pulverization. If wet mixing is used, a solvent is prepared. Suitable solvents include ketones such as acetone, alcohols such as ethanol and isopropanol, ethers, dioxane, acetonitrile, N-methyl-2-pyrrolidone (NMP), etc. It is more preferable to use an aprotic solvent that does not react easily with lithium. In this embodiment, acetone is used.

[0117] For mixing, for example, a ball mill or a bead mill can be used. When using a ball mill, it is preferable to use zirconia balls as the media. It is preferable to carry out this mixing and grinding process thoroughly to finely pulverize the mixture 804.

[0118] Next, in step S15, the materials mixed and crushed above are recovered, and in step S16, a mixture 804 is obtained.

[0119] The mixture 804 preferably has a D50 of 600 nm to 20 μm, and more preferably 1 μm to 10 μm.

[0120] In step S17, the mixture 804 is subjected to heat treatment (also called annealing). The heating temperature in step S17 is more preferably above the melting temperature of the mixture 804. Furthermore, the heating temperature is preferably below the decomposition temperature of LiCoO2 (1130°C).

[0121] By using LiF as fluoride 802 and annealing S17 with a lid, a cobalt-containing material 808 with good cycle properties can be produced. Furthermore, when LiF and MgF2 are used as fluoride 802, the eutectic point of LiF and MgF2 is around 742°C, so it is thought that if the annealing temperature of S17 is set to 742°C or higher, the reaction with LiCoO2 will be promoted and LiMO2 will be produced. In addition, an endothermic peak is observed around 820°C by differential scanning calorimetry (DSC measurement) for a mixture of LiF, MgF2, and LiCoO2. Therefore, an annealing temperature of 742°C or higher is preferred, and 820°C or higher is more preferred.

[0122] Therefore, the annealing temperature is preferably 742°C to 1130°C, more preferably 742°C to 1000°C. Furthermore, it is preferably 820°C to 1130°C, and more preferably 820°C to 1000°C.

[0123] Furthermore, in this embodiment, LiF, which is a fluoride, is considered to function as a flux. Therefore, since the volume inside the heating furnace is larger than the volume of the container and LiF is lighter than oxygen, it is expected that LiF will volatilize, and as the amount of LiF in mixture 804 decreases, the formation of LiMO2 will be suppressed. Therefore, it is necessary to heat the mixture while suppressing the volatilization of LiF.

[0124] Therefore, heating mixture 804 in an atmosphere containing LiF, that is, heating mixture 804 under conditions where the partial pressure of LiF in the heating furnace is high, suppresses the volatilization of LiF in mixture 804. By covering the mixture with a fluoride (LiF or MgF) that forms a eutectic mixture and annealing, the annealing temperature can be lowered to below the decomposition temperature of LiCoO2 (1130°C), specifically to between 742°C and 1000°C, allowing for efficient formation of LiMO2. As a result, a cobalt-containing material with good properties can be produced, and the annealing time can also be shortened.

[0125] An example of the annealing method in S17 is shown in Figure 5.

[0126] The heating furnace 120 shown in Figure 5 has a heating furnace space 102, a heating plate 104, a heater section 106, and an insulating material 108. It is more preferable to place a lid 118 on the container 116 during annealing. With this configuration, the space 119 formed by the container 116 and the lid 118 can be filled with a fluoride-containing atmosphere. During annealing, by maintaining the state by covering the space 119 so that the concentration of gasified fluoride remains constant or does not decrease, fluorine and magnesium can be incorporated near the particle surface. Since the volume of space 119 is smaller than the heating furnace space 102, a small amount of fluoride will volatilize, creating a fluoride-containing atmosphere. In other words, the reaction system can be made into a fluoride-containing atmosphere without significantly reducing the amount of fluoride contained in the mixture 804. Therefore, LiMO2 can be efficiently produced. Furthermore, by using the lid 118, the mixture 804 can be annealed in a fluoride-containing atmosphere simply and inexpensively.

[0127] Here, it is preferable that the valency of Co (cobalt) in the LiCoO2 produced according to one aspect of the present invention is approximately 3. Cobalt can be 2 or 3. Therefore, in order to suppress the reduction of cobalt, it is preferable that the atmosphere of the heating furnace space 102 contains oxygen, more preferably that the ratio of oxygen to nitrogen in the atmosphere of the heating furnace space 102 is greater than or equal to that of the atmosphere of air, and even more preferably that the oxygen concentration in the atmosphere of the heating furnace space 102 is greater than or equal to that of the atmosphere of air. Thus, it is necessary to introduce an oxygen-containing atmosphere into the heating furnace space. However, since cobalt atoms with magnesium atoms nearby may be more stable in the 2 valency state, not all cobalt atoms need to be 3.

[0128] Therefore, in one aspect of the present invention, before heating, the steps of creating an oxygen-containing atmosphere in the heating furnace space 102 and placing a container 116 containing the mixture 804 in the heating furnace space 102 are performed. By following this sequence, the mixture 804 can be annealed in an atmosphere containing oxygen and fluoride. Furthermore, it is preferable to seal the heating furnace space 102 during annealing to prevent gas from being carried to the outside. For example, it is preferable to perform the annealing without gas flow.

[0129] There are no particular restrictions on the method for creating an oxygen-containing atmosphere in the heating furnace space 102, but examples include exhausting the heating furnace space 102 and then introducing an oxygen-containing gas such as oxygen gas or dry air, and introducing an oxygen-containing gas such as oxygen gas or dry air for a certain period of time. In particular, it is preferable to introduce oxygen gas (oxygen replacement) after exhausting the heating furnace space 102. The atmosphere inside the heating furnace space 102 may be considered as an oxygen-containing atmosphere.

[0130] When a lid 118 is placed on the container 116 and heated in an oxygen-containing atmosphere, an appropriate amount of oxygen enters the container 116 through the gap in the lid 118, and an appropriate amount of fluoride can be retained inside the container 116.

[0131] Furthermore, fluorides and other substances adhering to the inner walls of the container 116 and lid 118 may be re-flyed upon heating and adhere to the mixture 804.

[0132] The annealing in step S17 is preferably carried out at an appropriate temperature and time. The appropriate temperature and time vary depending on conditions such as the particle size and composition of the composite oxide 801 in step S11. If the particles are small, a lower temperature or shorter time may be more preferable than when the particles are large. The process includes removing the lid after the annealing in S17.

[0133] For example, if the average particle size (D50) of the particles in step S11 is about 12 μm, the annealing time is preferably 3 hours or more, and more preferably 10 hours or more.

[0134] On the other hand, if the average particle size (D50) of the particles in step S11 is about 5 μm, the annealing time is preferably, for example, 1 hour or more and 10 hours or less, and more preferably about 2 hours.

[0135] The cooling time after annealing is preferably, for example, 10 hours or more and 50 hours or less.

[0136] Next, in step S18, the annealed material is recovered, and in step S19, a cobalt-containing material 808 is obtained.

[0137] [Structure of the positive electrode active material] Materials with a layered rock salt crystal structure, such as lithium cobalt oxide (LiCoO2), are known to have high discharge capacity and are excellent as positive electrode active materials for secondary batteries. Examples of materials with a layered rock salt crystal structure include composite oxides represented by LiMO2. Metal M includes the metals mentioned above. Furthermore, metal M may also include the metal X mentioned above in addition to the metals mentioned above.

[0138] It is known that the Jahn-Teller effect in transition metal compounds differs in strength depending on the number of electrons in the d orbitals of the transition metal.

[0139] In nickel-containing compounds, distortion can easily occur due to the Jahn-Teller effect. Therefore, when LiNiO2 is charged and discharged at high voltages, there is a concern that the crystal structure may collapse due to distortion. In LiCoO2, the effect of the Jahn-Teller effect is suggested to be smaller, and it may have better resistance to high-voltage charging and discharging, making it preferable.

[0140] The positive electrode active material will be explained using Figures 6 and 7.

[0141] The positive electrode active material produced according to one aspect of the present invention can reduce the displacement of the CoO2 layer during repeated high-voltage charging and discharging. Furthermore, it can reduce volume changes. Therefore, the compound can achieve excellent cycle characteristics. In addition, the compound can adopt a stable crystal structure in a high-voltage charged state. Therefore, when the compound is maintained in a high-voltage charged state, short circuits may be less likely to occur. In such cases, safety is further improved, which is preferable.

[0142] In this compound, the difference in crystal structure and volume per unit number of transition metal atoms between a fully discharged state and a high-voltage charged state is small.

[0143] Furthermore, the positive electrode active material in one aspect of the present invention comprises lithium, the metal M mentioned above, oxygen, and titanium. In addition, the positive electrode active material in one aspect of the present invention preferably contains a halogen such as fluorine or chlorine.

[0144] Furthermore, in each region, such as the surface layer, the interior, and the first region within the surface layer, the concentration of elements such as metal M has a gradient. That is, for example, at the boundaries of each region, the concentration of each element does not change abruptly, but changes in a gradient. Here, in addition to cobalt and magnesium, metal M can be used, for example, aluminum, nickel, etc. In such cases, aluminum and nickel each have a concentration gradient in their respective regions, such as the surface layer, the interior, and the first region within the surface layer.

[0145] A positive electrode active material according to one aspect of the present invention has a first region. When the positive electrode active material according to one aspect of the present invention has a particulate form, the first region preferably includes a region inside the particle surface. At least a part of the surface layer may also be included in the first region. The first region is preferably represented by a layered rock salt type structure, and this region is represented by a space group R-3m. The first region is a region having lithium and metal M. An example of the crystal structure of the first region before and after charging and discharging is shown in Figure 6. In addition to the region represented by the layered rock salt type structure described in Figure 6 below, the surface layer of the positive electrode active material according to one aspect of the present invention may have crystals having magnesium and oxygen, and having a structure different from the layered rock salt type structure.

[0146] Li in Figure 6 xThe crystal structure when the occupancy rate in CoO2 is x=1 is R-3m(O3), the same as in Figure 7. On the other hand, when x=0.2, the first region has a crystal structure different from the H1-3 type crystal structure. This structure has a space group R-3m and is not a spinel type crystal structure, but ions such as cobalt and magnesium occupy the oxygen 6-coordinate positions, and the arrangement of cations has a symmetry similar to that of the spinel type. Furthermore, the symmetry of the CoO2 layer in this structure is the same as that of the O3 type. Therefore, this structure is referred to as the O3' type crystal structure in this specification. Note that in the diagram of the O3' type crystal structure shown in Figure 6, lithium can be present at any lithium site with a probability of about 20%, but this is not limited to this. It may be present only at certain lithium sites. In addition, in both the O3 type crystal structure and the O3' type crystal structure, it is preferable that magnesium is present dilutely between the CoO2 layers, i.e., at the lithium sites. Furthermore, halogens such as fluorine may be present randomly and dilutely at the oxygen sites.

[0147] In the O3' type crystal structure, light elements such as lithium may occupy the oxygen 4-coordinate position, and in this case as well, the ion arrangement exhibits symmetry similar to that of the spinel type.

[0148] Furthermore, the O3' type crystal structure can be described as a crystal structure similar to the CdCl2 type crystal structure, although it has Li randomly placed between layers. This crystal structure similar to the CdCl2 type is formed when lithium nickelate is replaced with Li 0.06 This crystal structure is similar to that of NiO2 when charged to this level, but it is known that pure lithium cobaltate or layered rock salt-type cathode active materials containing a large amount of cobalt do not usually adopt this crystal structure.

[0149] In the first region, the change in crystal structure when charged at high voltage and a large amount of lithium is released is suppressed compared to the comparative example described later. For example, as shown by the dotted line in Figure 6, there is almost no displacement of the CoO2 layer in these crystal structures.

[0150] More specifically, the first aspect is the high structural stability even at high charging voltages. For example, in Figure 7, at a voltage of approximately 4.6V relative to the lithium metal potential, an H1-3 type crystal structure is formed. However, the positive electrode active material of one aspect of the present invention can maintain an R-3m(O3) crystal structure even at this charging voltage of approximately 4.6V. Furthermore, even at higher charging voltages, such as 4.65V to 4.7V relative to the lithium metal potential, the positive electrode active material of one aspect of the present invention can adopt an O3' type crystal structure. If the charging voltage is increased further above 4.7V, an H1-3 type crystal may finally be observed in the positive electrode active material of one aspect of the present invention. Moreover, at lower charging voltages (for example, when the charging voltage is between 4.5V and 4.6V relative to the lithium metal potential), the positive electrode active material of one aspect of the present invention may adopt an O3' type crystal structure.

[0151] Furthermore, in the case of a secondary battery, if graphite is used as the negative electrode active material, for example, the voltage of the secondary battery will decrease by the amount of the graphite's potential compared to the above. The potential of graphite is approximately 0.05V to 0.2V relative to the potential of lithium metal. Therefore, for example, even when the voltage of a secondary battery using graphite as the negative electrode active material is between 4.3V and 4.5V, the positive electrode active material of one embodiment of the present invention can maintain the R-3m(O3) crystal structure, and there is a region where the O3' type crystal structure can be adopted even when the charging voltage is increased, for example, when the secondary battery voltage is above 4.5V and below 4.6V. Moreover, even when the charging voltage is lower, for example, when the secondary battery voltage is between 4.2V and 4.3V, the positive electrode active material of one embodiment of the present invention may be able to adopt the O3' type crystal structure.

[0152] Therefore, in the first region, the crystal structure is less likely to collapse even when repeatedly charged and discharged at high voltage.

[0153] Furthermore, in one embodiment of the present invention, the difference in volume per unit number of cobalt atoms between the O3-type crystal structure and the O3'-type crystal structure in the discharge state is 2.5% or less, more specifically 2.2% or less.

[0154] Furthermore, in the O3' type crystal structure, the coordinates of cobalt and oxygen in the unit cell can be expressed as Co(0,0,0.5), O(0,0,x), and within the range of 0.20≦x≦0.25.

[0155] Magnesium, randomly and dilutely present between CoO2 layers, i.e., at lithium sites, has the effect of suppressing the displacement of the CoO2 layers when charged at high voltage. Therefore, the presence of magnesium between CoO2 layers makes it easier for an O3' type crystal structure to form.

[0156] However, if the heat treatment temperature is too high, cation mixing occurs, increasing the likelihood of magnesium entering the cobalt site. Magnesium present in the cobalt site may have little effect in maintaining the R-3m structure during high-voltage charging. 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.

[0157] Therefore, it is preferable to add a halogen compound such as a fluorine compound to lithium cobalt oxide before the heat treatment to distribute magnesium throughout the particles. Adding a halogen compound lowers the melting point of lithium cobalt oxide. Lowering the melting point makes it easier to distribute magnesium throughout the particles at a temperature where cation mixing is less likely to occur. Furthermore, if a fluorine compound is present, it can be expected that the corrosion resistance to hydrofluoric acid produced by the decomposition of the electrolyte will be improved.

[0158] Furthermore, if the magnesium concentration is increased beyond the desired value, the effect on stabilizing the crystal structure may decrease. This is thought to be because magnesium will enter not only the lithium sites but also the cobalt sites. The number of magnesium atoms in the positive electrode active material produced according to one aspect of the present invention is preferably 0.001 times or more and 0.1 times or less the number of cobalt atoms, more preferably greater than 0.01 times and less than 0.04 times, and even more preferably about 0.02 times. The magnesium concentration shown here may be, for example, a value obtained by elemental analysis of the entire particle of the positive electrode active material using ICP-MS, or it may be based on the value of the raw material composition during the process of producing the positive electrode active material.

[0159] The number of nickel atoms in the positive electrode active material according to one embodiment of the present invention is preferably 7.5% or less of the number of cobalt atoms, preferably 0.05% to 4%, and more preferably 0.1% to 2%. The nickel concentration shown herein may be a value obtained by performing elemental analysis of the entire particle of the positive electrode active material using, for example, ICP-MS, or it may be based on the mixing ratio of the raw materials in the process of manufacturing the positive electrode active material.

[0160] <Particle size> In one embodiment of the present invention, if the particle size of the positive electrode active material is too large, problems arise such as difficulty in lithium diffusion and excessive roughness of the surface of the active material layer when coated onto the current collector. On the other hand, if the particle size is too small, problems arise such as difficulty in supporting the active material layer when coating onto the current collector and excessive reaction with the electrolyte. Therefore, the average particle size (D50: also called the median diameter) is preferably 1 μm or more and 100 μm or less, more preferably 2 μm or more and 40 μm or less, and even more preferably 5 μm or more and 30 μm or less.

[0161] <Analysis method> Whether a positive electrode active material exhibits an O3'-type crystal structure when charged at high voltage can be determined by analyzing the high-voltage charged positive electrode using XRD, electron diffraction, neutron diffraction, electron spin resonance (ESR), nuclear magnetic resonance (NMR), etc. XRD is particularly preferable because it can analyze the symmetry of transition metals such as cobalt in the positive electrode active material with high resolution, compare the crystallinity and crystal orientation, analyze the periodic distortion of the lattice and crystallite size, and obtain sufficient accuracy even when measuring a positive electrode obtained by disassembling a secondary battery.

[0162] As described above, a positive electrode active material according to one aspect of the present invention is characterized by minimal change in crystal structure between a high-voltage charged state and a discharged state. Materials in which the crystal structure that changes significantly from the discharged state accounts for 50 wt% or more when charged at high voltage are undesirable because they cannot withstand high-voltage charging and discharging. It is important to note that simply adding impurity elements may not result in the desired crystal structure. For example, even if both materials are lithium cobalt oxide containing magnesium and fluorine, there are cases where the O3' type crystal structure accounts for 60 wt% or more when charged at high voltage, and cases where the H1-3 type crystal structure accounts for 50 wt% or more. Furthermore, at a predetermined voltage, the O3' type crystal structure may account for almost 100 wt%, and if the predetermined voltage is further increased, the H1-3 type crystal structure may be generated. Therefore, it is preferable that the crystal structure of the positive electrode active material according to one aspect of the present invention be analyzed by XRD or the like. By combining XRD and other analytical methods, more detailed analysis can be performed.

[0163] However, positive electrode active materials in a high-voltage charged or discharged state may undergo changes in their crystal structure when exposed to air. For example, they may change from an O3' type crystal structure to an H1-3 type crystal structure. Therefore, it is preferable to handle all samples in an inert atmosphere such as an argon-containing atmosphere.

[0164] The positive electrode active material shown in Figure 7 is lithium cobalt oxide (LiCoO2) without the addition of metal X. The lithium cobalt oxide shown in Figure 7 is Li xThe crystal structure changes in response to changes in the occupancy rate x within CoO2.

[0165] As shown in Figure 7, Li x Lithium cobalt oxide with an occupancy rate of x=1 in CoO2 has regions with a crystal structure of space group R-3m, and there are three CoO2 layers in a unit cell. For this reason, this crystal structure is sometimes called an O3 type crystal structure. The CoO2 layer is defined as a structure in which octahedral structures, in which oxygen atoms are coordinated to cobalt in a 6-coordinate manner, are continuous in a plane with shared edges.

[0166] Furthermore, when x=0, lithium cobalt oxide has a trigonal crystal structure with space group P-3m1, and one CoO2 layer exists in the unit cell. For this reason, this crystal structure is sometimes called the O1 type crystal structure.

[0167] Furthermore, conventional lithium cobalt oxide at x=0.24 has a crystal structure of space group R-3m. This structure can be described as a structure in which CoO2 structures such as P-3m1(O1) and LiCoO2 structures such as R-3m(O3) are alternately stacked. For this reason, this crystal structure is sometimes called the H1-3 type crystal structure. However, since actual lithium insertion and removal can be uneven, the H1-3 type crystal structure is experimentally observed from x=0.25. In reality, the H1-3 type crystal structure has twice the number of cobalt atoms per unit cell compared to other structures. However, in this specification, including Figure 7, the c-axis of the H1-3 type crystal structure is shown as half the unit cell to facilitate comparison with other structures.

[0168] As an example, the H1-3 type crystal structure can be represented by the coordinates of cobalt and oxygen in a unit cell as follows: Co(0,0,0.42150±0.00016), O1(0,0,0.27671±0.00045), and O2(0,0,0.11535±0.00045). O1 and O2 are oxygen atoms, respectively. Thus, the H1-3 type crystal structure is represented by a unit cell using one cobalt and two oxygen atoms. On the other hand, the O3' type crystal structure in one embodiment of the present invention is preferably represented by a unit cell using one cobalt and one oxygen atom. This indicates that the symmetry between cobalt and oxygen differs between the O3' type crystal structure and the H1-3 type structure, and that the O3' type crystal structure shows less variation from the O3 structure compared to the H1-3 type structure. The choice of which unit cell is preferable to represent the crystal structure of the positive electrode active material can be made, for example, in Rietveld analysis using XRD, by selecting the one that results in the smallest GOF (goodness of fit) value.

[0169] Li x When charging and discharging are repeated such that the occupancy rate x in CoO2 is 0.24 or less, conventional lithium cobalt oxide undergoes repeated changes in its crystal structure (i.e., non-equilibrium phase changes) between the H1-3 type crystal structure and the R-3m(O3) structure in the discharged state.

[0170] However, these two crystal structures exhibit a large displacement of the CoO2 layer. As shown by the dotted line and arrow in Figure 7, in the H1-3 type crystal structure, the CoO2 layer is significantly shifted from R-3m(O3). Such dynamic structural changes can negatively affect the stability of the crystal structure.

[0171] Furthermore, the volume difference is also significant. When comparing the same number of cobalt atoms, the volume difference between the H1-3 type crystal structure and the O3 type crystal structure in the discharged state is more than 3.0%.

[0172] In addition, the H1-3 type crystal structure, which consists of continuous CoO2 layers such as P-3m1(O1), is likely to be unstable.

[0173] Therefore, repeated high-voltage charging and discharging causes the crystal structure of lithium cobalt oxide to break down. This breakdown of the crystal structure leads to a deterioration of the cycle characteristics. This is thought to be because the breakdown of the crystal structure reduces the number of sites where lithium can exist stably, and also makes it more difficult for lithium to be inserted and removed.

[0174] [Negative electrode] Next, I will explain the negative electrode.

[0175] <Negative electrode active material> For example, alloy-based materials or carbon-based materials can be used as the negative electrode active material.

[0176] As the negative electrode active material, elements capable of undergoing charge-discharge reactions through alloying and dealloying reactions with lithium can be used. For example, materials containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc., can be used. Such elements have a larger capacity than carbon, and silicon in particular has a high theoretical capacity of 4200 mAh / g. For this reason, it is preferable to use silicon as the negative electrode active material. Compounds containing these elements may also be used. Examples include SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. In this context, elements capable of undergoing charge-discharge reactions through alloying and de-alloying reactions with lithium, and compounds containing such elements, are sometimes referred to as alloying materials.

[0177] In this specification, SiO refers to silicon monoxide, for example. Alternatively, SiO refers to SiO x It can also be expressed as follows. Here, x is preferably 1 or a value in its immediate vicinity. For example, x is preferably between 0.2 and 1.5, and preferably between 0.3 and 1.2.

[0178] Suitable carbon-based materials include graphite, easily graphitizable carbon (soft carbon), difficult-to-graphitize carbon (hard carbon), carbon nanotubes, graphene, and carbon black.

[0179] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spheroidal graphite having a spherical shape can be used as artificial graphite. For example, MCMB may have a spherical shape and is therefore preferable. Furthermore, it is relatively easy to reduce the surface area of ​​MCMB, which may also be preferable. Examples of natural graphite include flake graphite and spheroidized natural graphite.

[0180] When lithium ions are inserted into graphite (during the formation of lithium-graphite intercalation compounds), graphite exhibits a potential as low as that of lithium metal (0.05V to 0.3V vs. Li / Li). + This allows lithium-ion secondary batteries using graphite to exhibit a high operating voltage. Furthermore, graphite is preferable because it has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and higher safety compared to lithium metal.

[0181] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4Ti5O2) are used as negative electrode active materials. 12 ), lithium-graphite intercalation compound (Li x Oxides such as C6, niobium pentoxide (Nb2O5), tungsten oxide (WO2), and molybdenum oxide (MoO2) can be used.

[0182] Furthermore, as the negative electrode active material, a Li3N type structure is used, which is a lithium and transition metal binitride. 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 a preference.

[0183] Using a lithium-transition metal complex nitride is preferable because it contains lithium ions in the negative electrode active material, allowing it to be combined with lithium-ion-free materials such as V2O5 and Cr3O8 as the positive electrode active material. Even when using a lithium-ion-containing material as the positive electrode active material, the lithium-transition metal complex nitride can be used as the negative electrode active material by pre-desorbing the lithium ions contained in the positive electrode active material.

[0184] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, transition metal oxides that do not form alloys with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. Other materials that undergo a conversion reaction include oxides such as Fe2O3, CuO, Cu2O, RuO2, Cr2O3, and CoS 0.89 This can also occur with sulfides such as NiS and CuS, nitrides such as Zn3N2, Cu3N, and Ge3N4, phosphides such as NiP2, FeP2, and CoP3, and fluorides such as FeF3 and BiF3.

[0185] The conductive additive and binder that the negative electrode active material layer may have can be the same materials as those used for the conductive additive and binder that the positive electrode active material layer may have.

[0186] <Negative electrode current collector> In addition to the same materials as the positive electrode current collector, copper and other materials can also be used for the negative electrode current collector. It is preferable to use a material for the negative electrode current collector that does not alloy with carrier ions such as lithium.

[0187] [Electrolyte] As the electrolyte, for example, one of the following can be used: ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, 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 sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in any combination and ratio.

[0188] Furthermore, the electrolyte preferably contains fluorine. As a fluorine-containing electrolyte, for example, an electrolyte having one or more types of fluorinated cyclic carbonates and lithium ions can be used. Fluorinated cyclic carbonates can improve flammability and enhance the safety of lithium-ion secondary batteries.

[0189] As fluorinated cyclic carbonates, fluorinated ethylene carbonates such as monofluoroethylene carbonate (fluoroethylene carbonate, FEC, F1EC), difluoroethylene carbonate (DFEC, F2EC), trifluoroethylene carbonate (F3EC), and tetrafluoroethylene carbonate (F4EC) can be used. Note that DFEC has isomers such as cis-4,5 and trans-4,5. As an electrolyte, it is important to solvate lithium ions using one or more types of fluorinated cyclic carbonates and transport them within the electrolyte contained in the electrodes during charging and discharging in order to operate at low temperatures. By contributing to lithium ion transport during charging and discharging, rather than using fluorinated cyclic carbonates as small additives, low-temperature operation becomes possible.

[0190] By using fluorinated cyclic carbonates as the electrolyte, the desolvation energy required for lithium ions, which are solvated within the electrolyte contained in the electrode, to enter the active material particles is reduced. If this desolvation energy can be reduced, lithium ions will be more easily inserted into or removed from the active material particles even in the low-temperature range. Although lithium ions may move while remaining solvated, a hopping phenomenon may occur in which the coordinating solvent molecules are replaced. If desolvation from lithium ions becomes easier, movement due to the hopping phenomenon will become easier, and thus the movement of lithium ions may become easier.

[0191] Solvated lithium ions may form clusters in the electrolyte and move within the negative electrode, between the positive and negative electrodes, within the positive electrode, etc.

[0192] An example of a fluorinated cyclic carbonate is shown below.

[0193] Monofluoroethylene carbonate (FEC) is represented by the following formula (1).

[0194] [ka]

[0195] Tetrafluoroethylene carbonate (F4EC) is represented by the following formula (2).

[0196] [ka]

[0197] Difluoroethylene carbonate (DFEC) is represented by the following formula (3).

[0198] [ka]

[0199] Furthermore, by using one or more flame-retardant and low-volatility ionic liquids (room-temperature molten salts) as the solvent for the electrolyte, it is possible to prevent the secondary battery from rupturing or igniting even if the internal temperature rises due to an internal short circuit or overcharging. When the separator is impregnated with an ionic liquid, a flame-retardant secondary battery can be realized. Ionic liquids consist of cations and anions, and include organic cations and anions. Examples of organic cations include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, as well as aromatic cations such as imidazolium cations and pyridinium cations. Examples of anions include monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkyl sulfonate anions, tetrafluoroborate anions, perfluoroalkyl borate anions, hexafluorophosphate anions, or perfluoroalkyl phosphate anions.

[0200] As an ionic liquid having an imidazolium cation, for example, an ionic liquid represented by the following general formula (G1) can be used. In general formula (G1), R 1 R represents an alkyl group with 1 to 4 carbon atoms. 2 ~R 4 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R5 represents a main chain composed of an alkyl group or two or more atoms selected from C, O, Si, N, S, and P. 5 Substituents may be introduced into the main chain. Examples of substituents that can be introduced include alkyl groups and alkoxy groups.

[0201] [ka]

[0202] Examples of cations represented by general formula (G1) include 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-methyl-3-(propoxyethyl)imidazolium cation, and 1-hexyl-3-methylimidazolium cation.

[0203] As an ionic liquid having a pyridinium cation, for example, an ionic liquid represented by the following general formula (G2) may be used. In general formula (G2), R 6 R represents an alkyl group or a main chain composed of two or more atoms selected from C, O, Si, N, S, and P. 7 ~R 11 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Also, R 6 Substituents may be introduced into the main chain. Examples of substituents that can be introduced include alkyl groups and alkoxy groups.

[0204] [ka]

[0205] As ionic liquids having quaternary ammonium cations, for example, ionic liquids represented by the following general formulas (G3), (G4), (G5), and (G6) can be used.

[0206] [ka]

[0207] In general formula (G3), R 28 ~R 31 Each of these independently represents an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom.

[0208] [ka]

[0209] In general formula (G4), R 12 ~R 17 Each of these independently represents an alkyl group with 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom. An example of a cation represented by general formula (G4) is the 1-methyl-1-propylpyrrolidinium cation.

[0210] [ka]

[0211] In general formula (G5), R 18 ~R 24 Each of these independently represents an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom. Examples of cations represented by general formula (G5) include the N-methyl-N-propylpiperidinium cation and the 1,3-dimethyl-1-propylpiperidinium cation.

[0212] [ka]

[0213] In general formula (G6), n and m are between 1 and 3. α is between 0 and 6, where n is 1, α is between 0 and 4, n is 2, α is between 0 and 5, and n is 3, α is between 0 and 6. β is between 0 and 6, where m is 1, β is between 0 and 4, m is 2, β is between 0 and 5, and m is 3, β is between 0 and 6. Note that α or β being 0 means unsubstituted. Also, the case where both α and β are 0 is excluded. X or Y represents a linear or side-chain alkyl group having 1 to 4 carbon atoms, a linear or side-chain alkoxy group having 1 to 4 carbon atoms, or a linear or side-chain alkoxyalkyl group having 1 to 4 carbon atoms as a substituent.

[0214] As an ionic liquid having a tertiary sulfonium cation, for example, an ionic liquid represented by the following general formula (G7) can be used. In general formula (G7), R 25 ~R 27 Each of these independently represents a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or a phenyl group. Or, R 25 ~R 27 Alternatively, a main chain composed of two or more atoms selected from C, O, Si, N, S, and P may be used.

[0215] [ka]

[0216] As an ionic liquid having a quaternary phosphonium cation, for example, an ionic liquid represented by the following general formula (G8) can be used. In general formula (G8), R 32 ~R 35 Each of these independently represents a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, or a phenyl group. Or, R 32 ~R 35 Alternatively, a main chain composed of two or more atoms selected from C, O, Si, N, S, and P may be used.

[0217] [ka]

[0218] A shown in general formulas (G1) to (G8) - One or more of the following can be used: monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkyl sulfonic acid anions, tetrafluoroborate anions, perfluoroalkyl borate anions, hexafluorophosphate anions, and perfluoroalkyl phosphate anions.

[0219] As for monovalent amide anions, (C n F 2n+1 SO2)2N- (n = 0 or more and 3 or less), as the monovalent cyclic amide-based anion, (CF2SO2)2N - etc. can be used. As the monovalent methide-based anion, (C n F 2n+1 SO2)3C - (n = 0 or more and 3 or less), as the monovalent cyclic methide-based anion, (CF2SO2)2C - (CF3SO2), etc. can be used. As the fluoroalkyl sulfonic acid anion, (C m F 2m+1 SO3) - (m = 0 or more and 4 or less), etc. are exemplified. As the fluoroalkyl borate anion, {BF n (C m H k F 2m+1-k ) 4-n} - (n = 0 or more and 3 or less, m = 1 or more and 4 or less, k = 0 or more and 2m or less), etc. are exemplified. As the fluoroalkyl phosphate anion, {PF n (C m H k F 2m+1-k ) 6-n} - (n = 0 or more and 5 or less, m = 1 or more and 4 or less, k = 0 or more and 2m or less), etc. are exemplified.

[0220] Also, as the monovalent amide-based anion, for example, one or more of bis(fluorosulfonyl)amide anion and bis(trifluoromethanesulfonyl)amide anion can be used.

[0221] Also, the ionic liquid may have one or more of hexafluorophosphate anion and tetrafluoroborate anion.

[0222] Hereinafter, the anion represented by (FSO2)2N - may be represented as FSA anion, and the anion represented by (CF3SO2)2N - may be represented as TFSA anion.

[0223] The secondary battery according to one aspect of the present invention has, for example, one or more of alkali metal ions such as sodium ions and potassium ions, and alkaline earth metal ions such as calcium ions, strontium ions, barium ions, beryllium ions, and magnesium ions as carrier ions.

[0224] When lithium ions are used as carrier ions, for example, the electrolyte contains a lithium salt. Examples of lithium salts include LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 、Li2B 12 Cl 12 、LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. can be used.

[0225] In this specification, the electrolyte is a general term including solid, liquid, or semi-solid electrolyte materials, etc.

[0226] Interfaces existing in the secondary battery, such as the interface between the active material and the electrolyte, are likely to deteriorate. In the secondary battery according to one aspect of the present invention, by having an electrolyte containing fluorine, it is possible to prevent deterioration that may occur at the interface between the active material and the electrolyte, typically alteration of the electrolyte or increase in the viscosity of the electrolyte. DFEC with two fluorine bonds and F4EC with four fluorine bonds have lower viscosities and weaker coordination bonds with lithium compared to FEC with one fluorine bond. Therefore, it is possible to reduce the adhesion of high-viscosity decomposition products to the active material particles. When high-viscosity decomposition products adhere to or wrap around the active material particles, it becomes difficult for lithium ions to move at the interface of the active material particles. The solvation of lithium ions with an electrolyte containing fluorine alleviates the formation of decomposition products on the surface of the active material (positive electrode active material or negative electrode active material). Also, by using an electrolyte containing fluorine, it is possible to prevent the generation and growth of dendrites by preventing the adhesion of decomposition products.

[0227] Another characteristic is the use of an electrolyte containing fluorine as the main component, with the fluorine-containing electrolyte being 5% or more by volume, 10% or more by volume, preferably 30% to 100% by volume.

[0228] In this specification, the main component of the electrolyte refers to a component that accounts for 5% or more by volume of the total electrolyte of the secondary battery. Furthermore, "5% or more by volume of the total electrolyte of the secondary battery" here refers to the proportion of the total electrolyte measured during the manufacture of the secondary battery. In addition, when a secondary battery is disassembled after its manufacture, it is difficult to quantify the proportion of each of the multiple types of electrolytes, but it is possible to determine whether a particular organic compound accounts for 5% or more by volume of the total electrolyte.

[0229] By using an electrolyte containing fluorine, a secondary battery capable of operating over a wide temperature range, specifically from -40°C to 150°C, preferably from -40°C to 85°C, can be realized.

[0230] Furthermore, additives such as vinylene carbonate, propanesultone (PS), tert-butylbenzene (TBB), lithium bis(oxalate)borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte. The concentration of the additive should be, for example, 0.1% or more and less than 5% by volume relative to the total electrolyte.

[0231] In addition to the above, the electrolyte may also contain one or more aprotic organic solvents such as γ-butyrolactone, acetonitrile, dimethoxyethane, and tetrahydrofuran.

[0232] Furthermore, the presence of a polymer material that gels the electrolyte enhances safety against leakage and other issues. Typical examples of polymer materials that gel include silicone gels, acrylic gels, acrylonitrile gels, polyethylene oxide gels, polypropylene oxide gels, and fluorine-based polymer gels.

[0233] As polymer materials, for example, polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVdF, and polyacrylonitrile, as well as copolymers containing these, can be used. For example, PVdF-HFP, which is a copolymer of PVdF and hexafluoropropylene (HFP), can be used. Furthermore, the polymer material formed may have a porous structure.

[0234] [Exterior] For the outer casing of a secondary battery, metal materials such as aluminum and / or resin materials can be used. A film-like outer casing can also be used. As a film, for example, a three-layer film can be used, in which a highly flexible metal thin film such as aluminum, stainless steel, copper, or nickel is provided on a film made of materials such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide, and an insulating synthetic resin film such as a polyamide resin or polyester resin is provided on the metal thin film as the outer surface of the outer casing.

[0235] This embodiment can be used in appropriate combination with other embodiments.

[0236] (Embodiment 2) This embodiment describes a method for manufacturing a secondary battery.

[0237] <Method 1 for manufacturing laminated rechargeable batteries> Here, an example of a method for manufacturing a laminate-type secondary battery, whose external view is shown in Figures 8A and 8B, will be explained using Figures 9A and 9B and Figures 10A and 10B. The secondary battery 500 shown in Figures 8A and 8B has a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511.

[0238] First, prepare a positive electrode 503, a negative electrode 506, and a separator 507. FIG. 9A shows an example of the positive electrode 503 and the negative electrode 506. The positive electrode 503 has a positive electrode active material layer 502 on a positive electrode current collector 501. Also, the positive electrode 503 preferably has a tab region where the positive electrode current collector 501 is exposed. The negative electrode 506 has a negative electrode active material layer 505 on a negative electrode current collector 504. Also, the negative electrode 506 preferably has a tab region where the negative electrode current collector 504 is exposed.

[0239] Next, stack the negative electrode 506, the separator 507, and the positive electrode 503. FIG. 9B shows the stacked negative electrode 506, separator 507, and positive electrode 503. Here, an example of using five sets of negative electrodes and four sets of positive electrodes is shown. The stacked negative electrode 506, separator 507, and positive electrode 503 can also be called a laminate composed of a negative electrode, a separator, and a positive electrode.

[0240] Next, join the tab regions of the positive electrode 503 to each other and join a positive electrode lead electrode 510 to the tab region of the outermost positive electrode. For the joining, for example, ultrasonic welding or the like can be used. Similarly, join the tab regions of the negative electrode 506 to each other and join a negative electrode lead electrode 511 to the tab region of the outermost negative electrode.

[0241] Next, arrange the negative electrode 506, the separator 507, and the positive electrode 503 on the exterior body 509.

[0242] Next, as shown in FIG. 10A, bend the exterior body 509 at the portion indicated by the broken line. Then, join the outer peripheral portion of the exterior body 509. For the joining, for example, thermocompression bonding or the like can be used. At this time, provide a region (hereinafter referred to as an inlet 516) that is not joined to a part (or one side) of the exterior body 509 so that the electrolyte 508 can be inserted later.

[0243] Next, as shown in FIG. 10B, introduce the electrolyte 508 into the interior of the exterior body 509 from the inlet 516 provided in the exterior body 509. The introduction of the electrolyte 508 is preferably performed under a reduced pressure atmosphere or an inert atmosphere. And finally, join the inlet 516. In this way, a laminated secondary battery 500 can be manufactured.

[0244] In the above example, the positive lead electrode 510 and the negative lead electrode 511 were led out of the casing from the same side to create the secondary battery 500 shown in Figure 8A. Alternatively, the secondary battery 500 shown in Figure 8B can be created by leading the positive lead electrode 510 and the negative lead electrode 511 out of the casing from opposite sides.

[0245] <Method for manufacturing laminated rechargeable batteries, part 2> Next, an example of a method for manufacturing a laminate-type secondary battery 600, whose external view is shown in Figure 11, will be explained using Figures 12, 13, 14A to 14D, and 15A to 15F. The secondary battery 600 shown in Figure 11 has a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511. The outer casing 509 is sealed in region 514.

[0246] A laminate-type secondary battery 600 can be manufactured, for example, using the manufacturing apparatus shown in Figure 12. The manufacturing apparatus 570 shown in Figure 12 has a component input chamber 571, a transport chamber 572, a processing chamber 573, and a component removal chamber 576. Each chamber can be configured to be connected to various exhaust mechanisms depending on the application. Each chamber can also be configured to be connected to various gas supply mechanisms depending on the application. To suppress the entry of impurities into the manufacturing apparatus 570, it is preferable to supply an inert gas into the manufacturing apparatus 570. It is preferable that the gas supplied to the inside of the manufacturing apparatus 570 is purified to a high degree by a gas purifier before being introduced into the manufacturing apparatus 570. The component input chamber 571 is a chamber for inputting the positive electrode, separator, negative electrode, casing, etc. into the manufacturing apparatus 570. The transport chamber 572 has a transport mechanism 580. The processing chamber 573 has a stage and an electrolyte dropping mechanism. The component removal room 576 is a room for removing the manufactured secondary batteries from the manufacturing apparatus 570.

[0247] The procedure for manufacturing the laminate-type rechargeable battery 600 is as follows:

[0248] First, the outer casing 509b is placed on the stage 591 of the processing chamber 573, and then the positive electrode 503 is placed on the outer casing 509b (Figures 14A and 14B). Next, the electrolyte 515a is dropped onto the positive electrode 503 from the nozzle 594 (Figures 14C and 14D). Figure 14D is a cross-section corresponding to the dashed line AB in Figure 14C. Note that the stage 591 may be omitted in some cases to avoid making the drawings too complex. Any of the dropping methods can be used, such as the dispensing method, spray method, or inkjet method. In addition, the ODF (One Drop Fill) method can be used for dropping the electrolyte.

[0249] By moving the nozzle 594, the electrolyte 515a can be dropped onto the entire surface of the positive electrode 503. Alternatively, the electrolyte 515a may be dropped onto the entire surface of the positive electrode 503 by moving the stage 591.

[0250] It is preferable that the electrolyte is dropped from a position where the shortest distance from the bottom surface to the droplet is greater than 0 mm and less than or equal to 1 mm.

[0251] Furthermore, it is preferable to adjust the viscosity of the electrolyte being dispensed from the nozzle as appropriate. If the total viscosity of the electrolyte is within the range of 0.3 mPa·s to 1000 mPa·s at room temperature (25°C), it can be dispensed from the nozzle.

[0252] Furthermore, since the viscosity of the electrolyte changes with its temperature, it is preferable to appropriately adjust the temperature of the electrolyte being added dropwise. The temperature of the electrolyte is preferably above its melting point, below its boiling point, or below its flash point.

[0253] Next, the separator 507 is placed on the positive electrode 503 so as to overlap the entire surface of the positive electrode 503 (Figure 15A). Then, the electrolyte 515b is dropped onto the separator 507 using the nozzle 594 (Figure 15B). After that, the negative electrode 506 is placed on the separator 507 (Figure 15C). The negative electrode 506 is placed overlapping the separator 507 so that it does not protrude from the separator 507 when viewed from above. Then, the electrolyte 515c is dropped onto the negative electrode 506 using the nozzle 594 (Figure 15D). After that, the laminate 512 shown in Figure 13 can be fabricated by further stacking the laminate of the positive electrode 503, separator 507, and negative electrode 506. Next, the positive electrode 503, separator 507, and negative electrode 506 are sealed by the outer casings 509a and 509b (Figures 15E and 15F).

[0254] By arranging multiple laminates 512 on the outer casing 509b, multi-faceted processing can be achieved. After sealing the outer casings 509a and 509b with a region 514 so that each laminate 512 surrounds the active material layer, multiple secondary batteries can be individually separated by dividing them outside the region 514.

[0255] During sealing, first, a frame-shaped resin layer 513 is formed on the outer casing 509b. Next, at least a portion of the resin layer 513 is cured by irradiating it with light under reduced pressure. Then, sealing is performed in region 514 by thermocompression bonding or welding under atmospheric pressure. Alternatively, sealing may be performed only by thermocompression bonding or welding without the above-mentioned light irradiation sealing.

[0256] Although Figure 11 shows an example where the outer casing 509 is sealed on all four sides (sometimes called a four-sided seal), it may also be sealed on three sides (sometimes called a three-sided seal), as shown in Figures 8A and 8B.

[0257] Through the above process, a laminate-type secondary battery 600 can be manufactured.

[0258] <Other secondary batteries and their manufacturing methods 1> Figure 16 shows an example of a cross-sectional view of a laminate according to one aspect of the present invention. The laminate 550 shown in Figure 16 is manufactured by placing a single separator between the positive and negative electrodes while bending it.

[0259] In the laminate 550, a single separator 507 is folded multiple times so as to be sandwiched between the positive electrode active material layer 502 and the negative electrode active material layer 505. In Figure 16, since six layers each of positive electrodes 503 and negative electrodes 506 are laminated, the separator 507 is folded at least five times. In addition to being provided sandwiched between the positive electrode active material layer 502 and the negative electrode active material layer 505, the separator 507 may also be further folded so that multiple positive electrodes 503 and negative electrodes 506 are bundled together with tape or the like.

[0260] In one embodiment of the present invention, a method for manufacturing a secondary battery, the electrolyte can be dropped onto the positive electrode 503 after it has been placed. Similarly, the electrolyte can be dropped onto the negative electrode 506 after it has been placed. Furthermore, in one embodiment of the present invention, the electrolyte can be dropped onto the separator 507 before it has been folded, or after the separator 507 has been folded and placed on top of the negative electrode 506 or the positive electrode 503. By dropping the electrolyte onto at least one of the negative electrode 506, the separator 507, and the positive electrode 503, the electrolyte can be impregnated into the negative electrode 506, the separator 507, or the positive electrode 503.

[0261] The secondary battery 970 shown in Figure 17A has a laminate 972 inside the housing 971. Terminals 973b and 974b are electrically connected to the laminate 972. At least a portion of terminal 973b and at least a portion of terminal 974b are exposed to the outside of the housing 971.

[0262] As the laminate 972, a structure in which a positive electrode, a negative electrode, and a separator are laminated can be applied. Alternatively, as the laminate 972, a structure in which the positive electrode, negative electrode, and separator are wound can be applied, and so on.

[0263] For example, as the laminate 972, a laminate having a structure in which the separator is folded back, as shown in Figure 16, can be used.

[0264] An example of a method for fabricating the laminate 972 will be explained using Figures 17B and 17C.

[0265] First, as shown in Figure 17B, a strip-shaped separator 976 is placed on top of the positive electrode 975a, and the negative electrode 977a is placed on top of the positive electrode 975a with the separator 976 in between. Then, the separator 976 is folded back and placed on top of the negative electrode 977a. Next, as shown in Figure 17C, the positive electrode 975b is placed on top of the negative electrode 977a with the separator 976 in between. In this way, by folding back the separator and arranging the positive and negative electrodes in order, a laminate 972 can be manufactured. A structure including a laminate manufactured in this way is sometimes called a "zigzag structure".

[0266] Next, an example of a method for manufacturing the secondary battery 970 will be explained using Figures 18A to 18C.

[0267] First, as shown in Figure 18A, the positive lead electrode 973a is electrically connected to the positive electrode of the laminate 972. Specifically, for example, tab regions can be provided on each of the positive electrodes of the laminate 972, and each tab region and the positive lead electrode 973a can be electrically connected by welding or the like. In addition, the negative lead electrode 974a is electrically connected to the negative electrode of the laminate 972.

[0268] One laminate 972 may be placed inside the housing 971, or multiple laminates 972 may be placed inside. Figure 18B shows an example in which two sets of laminates 972 are prepared.

[0269] Next, as shown in Figure 18C, the prepared laminate 972 is placed inside the housing 971, terminals 973b and 974b are attached, and the housing 971 is sealed. It is preferable to electrically connect the conductor 973c to each positive lead electrode 973a of the multiple laminates 972. It is also preferable to electrically connect the conductor 974c to each negative lead electrode 974a of the multiple laminates 972. Terminal 973b is electrically connected to the conductor 973c, and terminal 974b is electrically connected to the conductor 974c. The conductor 973c may have a conductive region and an insulating region. Similarly, the conductor 974c may have a conductive region and an insulating region.

[0270] A metal material (such as aluminum) can be used for the housing 971. Furthermore, when a metal material is used for the housing 971, it is preferable to coat the surface with resin or the like. Alternatively, a resin material can be used for the housing 971.

[0271] It is preferable to provide a safety valve or overcurrent protection element in the housing 971. The safety valve is a valve that releases gas when the inside of the housing 971 reaches a predetermined pressure in order to prevent the battery from rupturing.

[0272] <Other secondary batteries and their manufacturing methods 2> Figure 19C shows an example of a cross-sectional view of a secondary battery according to another embodiment of the present invention. The secondary battery 560 shown in Figure 19C is manufactured using the laminate 130 shown in Figure 19A and the laminate 131 shown in Figure 19B. In Figure 19C, the laminate 130, laminate 131, and separator 507 are shown in part for clarity.

[0273] As shown in Figure 19A, the laminate 130 is constructed by stacking a positive electrode 503 having positive electrode active material layers on both sides of the positive electrode current collector, a separator 507, a negative electrode 506 having negative electrode active material layers on both sides of the negative electrode current collector, a separator 507, and a positive electrode 503 having positive electrode active material layers on both sides of the positive electrode current collector in this order.

[0274] As shown in Figure 19B, the laminate 131 is constructed by stacking a negative electrode 506 having negative electrode active material layers on both sides of the negative electrode current collector, a separator 507, a positive electrode 503 having positive electrode active material layers on both sides of the positive electrode current collector, a separator 507, and a negative electrode 506 having negative electrode active material layers on both sides of the negative electrode current collector in this order.

[0275] A method for manufacturing a secondary battery according to one aspect of the present invention can be applied when manufacturing a laminate. Specifically, when stacking the negative electrode 506, separator 507, and positive electrode 503 to manufacture the laminate, an electrolyte is dropped onto at least one of the negative electrode 506, separator 507, and positive electrode 503. By dropping multiple drops of the electrolyte, the negative electrode 506, separator 507, or positive electrode 503 can be impregnated with the electrolyte.

[0276] As shown in Figure 19C, the multiple laminates 130 and the multiple laminates 131 are covered by a wound separator 507.

[0277] Furthermore, in a method for manufacturing a secondary battery according to one aspect of the present invention, the electrolyte can be dropped onto the laminate 130 after the laminate 130 has been placed. Similarly, the electrolyte can be dropped onto the laminate 131 after the laminate 131 has been placed. In addition, the electrolyte can be dropped onto the separator 507 before it is folded, or after the separator 507 has been folded and stacked with the laminate. By dropping multiple drops of the electrolyte, the laminate 130, laminate 131, or separator 507 can be impregnated with the electrolyte.

[0278] <Other secondary batteries and their manufacturing methods 3> Another embodiment of the present invention, a secondary battery, will be described with reference to Figures 20 and 21. The secondary battery shown here can be called a wound-type secondary battery, etc.

[0279] The secondary battery 913 shown in Figure 20A has a wound body 950 with terminals 951 and 952 inside a housing 930. The wound body 950 is immersed in an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, while terminal 951 is not in contact with the housing 930 due to the use of an insulating material or the like. In Figure 20A, the housing 930 is shown separated for convenience, but in reality, the wound body 950 is covered by the housing 930, and terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (e.g., aluminum) or a resin material.

[0280] Furthermore, as shown in Figure 20B, the housing 930 shown in Figure 20A may be formed from multiple materials. For example, in the secondary battery 913 shown in Figure 20B, housing 930a and housing 930b are bonded together, and the winding body 950 is provided in the area surrounded by housing 930a and housing 930b.

[0281] For the housing 930a, an insulating material such as organic resin can be used. In particular, by using a material such as organic resin on the surface where the antenna is formed, shielding of the electric field by the secondary battery 913 can be suppressed. If the shielding of the electric field by housing 930a is small, the antenna may be placed inside housing 930a. For housing 930b, for example, a metal material can be used.

[0282] Furthermore, the structure of the wound body 950 is shown in Figure 20C. The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other with the separator 933 in between, and the stacked sheets are wound up. Note that multiple stacks of the negative electrode 931, positive electrode 932, and separator 933 may be stacked.

[0283] In a method for manufacturing a secondary battery according to one aspect of the present invention, when stacking the negative electrode 931, separator 933, and positive electrode 932, an electrolyte is dropped onto at least one of the negative electrode 931, separator 933, and positive electrode 932. In other words, it is preferable to drop the electrolyte before rolling up the stacked sheet. By dropping multiple drops of the electrolyte, the negative electrode 931, separator 933, or positive electrode 932 can be impregnated with the electrolyte.

[0284] Alternatively, the secondary battery 913 may have a wound body 950a as shown in Figure 21A. The wound body 950a shown in Figure 21A has a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.

[0285] The separator 933 has a wider width than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. Furthermore, it is preferable from a safety standpoint that the negative electrode active material layer 931a is wider than the positive electrode active material layer 932a. In addition, a wound body 950a of this shape is preferable because it offers good safety and productivity.

[0286] As shown in Figure 21B, the negative terminal 931 is electrically connected to terminal 951. Terminal 951 is electrically connected to terminal 911a. The positive terminal 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0287] As shown in Figure 21C, the coiled body 950a and the electrolyte are covered by the housing 930, forming a secondary battery 913. It is preferable to provide a safety valve, an overcurrent protection element, etc., in the housing 930. The safety valve is temporarily opened only when the internal pressure inside the housing 930 exceeds a predetermined level in order to prevent the battery from rupturing.

[0288] As shown in Figure 21B, the secondary battery 913 may have multiple windings 950a. By using multiple windings 950a, a secondary battery 913 with a larger charge and discharge capacity can be made.

[0289] This embodiment can be combined with other embodiments as appropriate.

[0290] (Embodiment 3) In this embodiment, an example of the application of a secondary battery according to one aspect of the present invention will be explained with reference to Figures 22 to 31.

[0291] [vehicle] First, we will show an example of applying a secondary battery according to one aspect of the present invention to an electric vehicle (EV).

[0292] Figure 22C shows a block diagram of a vehicle with a motor. The electric vehicle is equipped with a first battery 1301a, 1301b as the main secondary battery for propulsion, and a second battery 1311 that supplies power to the inverter 1312 that starts the motor 1304. The second battery 1311 is also called the cranking battery or starter battery. The second battery 1311 only needs to have high output, and does not require a large capacity, so the capacity of the second battery 1311 is smaller than that of the first batteries 1301a, 1301b.

[0293] For example, one or both of the first batteries 1301a and 1301b can be a secondary battery manufactured using a secondary battery manufacturing method according to one aspect of the present invention.

[0294] In this embodiment, an example is shown in which two first batteries 1301a and 1301b are connected in parallel, but three or more may be connected in parallel. Also, if the first battery 1301a can store sufficient power, the first battery 1301b may not be necessary. By configuring a battery pack with multiple secondary batteries, a large amount of power can be extracted. Multiple secondary batteries may be connected in parallel, in series, or connected in parallel and then in series. Multiple secondary batteries are also called a battery pack.

[0295] Furthermore, the vehicle-mounted secondary battery has a service plug or circuit breaker that can cut off high voltage without using tools in order to interrupt power from multiple secondary batteries, and this is provided in the first battery 1301a.

[0296] Furthermore, the power from the first batteries 1301a and 1301b is mainly used to rotate the motor 1304, but also supplies power to 42V (high-voltage) onboard components (electric power steering 1307, heater 1308, defogger 1309, etc.) via the DC-DC circuit 1306. If a rear motor 1317 is located on the rear wheels, the first battery 1301a is also used to rotate the rear motor 1317.

[0297] Furthermore, the second battery 1311 supplies power to 14V (low-voltage) in-vehicle components (audio 1313, power windows 1314, lights 1315, etc.) via the DC-DC circuit 1310.

[0298] Furthermore, the first battery 1301a will be explained using Figure 22A.

[0299] Figure 22A shows an example of a large battery pack 1415. One electrode of the battery pack 1415 is electrically connected to the control circuit unit 1320 by wiring 1421. The other electrode is electrically connected to the control circuit unit 1320 by wiring 1422. The battery pack may also be configured by connecting multiple secondary batteries in series.

[0300] Furthermore, the control circuit section 1320 may also use a memory circuit that includes a transistor made of an oxide semiconductor. A charging control circuit or battery control system having a memory circuit that includes a transistor made of an oxide semiconductor may be referred to as a BTOS (Battery operating system or Battery oxide semiconductor).

[0301] The control circuit unit 1320 detects the terminal voltage of the secondary battery and manages the charging and discharging state of the secondary battery. For example, to prevent overcharging, both the output transistor of the charging circuit and the cutoff switch can be turned off almost simultaneously.

[0302] Furthermore, an example of a block diagram of the battery pack 1415 shown in Figure 22A is shown in Figure 22B.

[0303] The control circuit unit 1320 includes a switch unit 1324 that includes at least a switch to prevent overcharging and a switch to prevent over-discharging, a control circuit 1322 that controls the switch unit 1324, and a voltage measurement unit for the first battery 1301a. The control circuit unit 1320 has upper and lower voltage limits set for the secondary battery used, and limits the upper limit of external current or the upper limit of output current to the outside. Within the range between the lower voltage and upper voltage of the secondary battery, it is within the voltage range for which use is recommended, and if it goes outside this range, the switch unit 1324 activates and functions as a protection circuit. The control circuit unit 1320 can also be called a protection circuit because it controls the switch unit 1324 to prevent over-discharge or overcharge. For example, if the control circuit 1322 detects a voltage that is likely to cause overcharging, it cuts off the current by turning off the switch of the switch unit 1324. Furthermore, a PTC element may be provided in the charge / discharge path to provide a function to cut off the current in response to the rise in temperature. Furthermore, the control circuit unit 1320 has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).

[0304] The switch section 1324 can be constructed using a combination of n-channel transistors and / or p-channel transistors. The switch section 1324 is not limited to switches using Si transistors made of single-crystal silicon; for example, the switch section 1324 may be formed using power transistors made of Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), InP (indium phosphide), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), GaOx (gallium oxide; x is a real number greater than 0), etc. Furthermore, since memory elements using OS transistors can be freely arranged by stacking them on circuits using Si transistors, integration can be easily achieved. Also, since OS transistors can be manufactured using the same manufacturing equipment as Si transistors, they can be manufactured at low cost. That is, a control circuit section 1320 using OS transistors can be stacked on the switch section 1324 and integrated into a single chip. Since the volume occupied by the control circuit unit 1320 can be reduced, miniaturization becomes possible.

[0305] The first batteries 1301a and 1301b primarily supply power to 42V (high-voltage) onboard equipment, while the second battery 1311 supplies power to 14V (low-voltage) onboard equipment. Lead-acid batteries are often used for the second battery 1311 due to their cost advantages.

[0306] This embodiment shows an example in which lithium-ion secondary batteries are used for both the first battery 1301a and the second battery 1311. The second battery 1311 may be a lead-acid battery, an all-solid-state battery, or an electric double-layer capacitor.

[0307] Furthermore, the regenerative energy generated by the rotation of the tire 1316 is sent to the motor 1304 via the gear 1305 and charged to the second battery 1311 via the control circuit unit 1321 from the motor controller 1303 or battery controller 1302. Alternatively, it is charged to the first battery 1301a via the control circuit unit 1320 from the battery controller 1302. Alternatively, it is charged to the first battery 1301b via the control circuit unit 1320 from the battery controller 1302. In order to efficiently charge the regenerative energy, it is desirable that the first batteries 1301a and 1301b are capable of rapid charging.

[0308] The battery controller 1302 can set the charging voltage and charging current of the first batteries 1301a and 1301b. The battery controller 1302 can set the charging conditions according to the charging characteristics of the secondary battery being used and enable rapid charging.

[0309] Although not shown in the diagram, when connected to an external charger, the charger's outlet or connection cable is electrically connected to the battery controller 1302. Power supplied from the external charger charges the first batteries 1301a and 1301b via the battery controller 1302. In some chargers, a control circuit is provided, and the functions of the battery controller 1302 may not be used, but it is preferable to charge the first batteries 1301a and 1301b via the control circuit unit 1320 to prevent overcharging. In some cases, the connection cable or the charger's connection cable may also have a control circuit. The control circuit unit 1320 is sometimes called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) installed in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. The ECU also includes a microcomputer. The ECU also uses a CPU or GPU.

[0310] Next, an example of implementing a secondary battery according to one aspect of the present invention in a vehicle, typically a transport vehicle, will be described.

[0311] By mounting a secondary battery according to one aspect of the present invention in a vehicle, next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV) can be realized. Furthermore, secondary batteries can also be mounted in agricultural machinery such as electric tractors, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, electric carts, small or large vessels, submarines, aircraft such as fixed-wing or rotary-wing aircraft, rockets, satellites, space probes or planetary probes, and other transport vehicles. By using the method for manufacturing a secondary battery according to one aspect of the present invention, large secondary batteries can be produced. Therefore, a secondary battery according to one aspect of the present invention is suitably used in transport vehicles.

[0312] Figures 23A to 23E show a transport vehicle using a secondary battery according to one embodiment of the present invention. The automobile 2001 shown in Figure 23A is an electric vehicle that uses an electric motor as a power source for driving. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as power sources for driving. When a secondary battery is mounted on a vehicle, the secondary battery is installed in one or more locations. The automobile 2001 shown in Figure 23A has the battery pack 1415 shown in Figure 22A. The battery pack 1415 has a secondary battery module. Preferably, the battery pack 1415 further has a charge control device electrically connected to the secondary battery module. The secondary battery module has one or more secondary batteries.

[0313] Furthermore, the automobile 2001 can be charged by receiving power from an external charging facility via a plug-in or contactless power supply method to the secondary battery it possesses. For charging, the charging method or connector specifications may be carried out appropriately using a prescribed method such as CHAdeMO® or Combo. The charging device may be a charging station installed in a commercial facility, or it may be a household power supply. For example, the secondary battery mounted on the automobile 2001 can be charged by an external power supply using plug-in technology. Charging can be performed by converting AC power to DC power via a conversion device such as an AC-DC converter.

[0314] Although not shown in the diagram, the vehicle can also be charged by mounting a power receiving device on the vehicle and receiving power wirelessly from a ground-based power transmission device. In this wireless power supply method, charging can be performed not only when the vehicle is stopped but also while it is in motion by incorporating the power transmission device into the road or exterior wall. Furthermore, this wireless power supply method can be used to transmit and receive power between two vehicles. In addition, solar panels can be installed on the exterior of the vehicle to charge the secondary battery when the vehicle is stopped or in motion. For such wireless power supply, electromagnetic induction or magnetic resonance methods can be used.

[0315] Figure 23B shows a large transport vehicle 2002 equipped with an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 has a maximum voltage of 170V, achieved by connecting 48 cells in series, each consisting of four secondary batteries with a voltage of 3.5V to 4.7V. The secondary battery module of the battery pack 2201 has the same functions as Figure 23A, except for differences in the number of secondary batteries that make up the module, so the explanation is omitted.

[0316] Figure 23C shows, as an example, a large transport vehicle 2003 equipped with an electrically controlled motor. The secondary battery module of the transport vehicle 2003 has a maximum voltage of 600V, achieved by connecting more than 100 secondary batteries with voltages of 3.5V to 4.7V in series. Therefore, secondary batteries with small variation in characteristics are required. By using the secondary battery manufacturing method according to one aspect of the present invention, secondary batteries with stable battery characteristics can be manufactured, enabling low-cost mass production from a yield standpoint. Furthermore, since it has the same functions as Figure 23A except for differences such as the number of secondary batteries constituting the secondary battery module of the battery pack 2202, a further explanation is omitted.

[0317] Figure 23D shows an aircraft 2004 having a fuel-burning engine as an example. The aircraft 2004 shown in Figure 23D has landing gear for takeoff and landing, and can therefore be considered part of a transport vehicle. It has a battery pack 2203 which includes a secondary battery module composed of multiple secondary batteries connected together and a charging control device.

[0318] The secondary battery module of aircraft 2004 has a maximum voltage of 32V, for example, by connecting eight 4V secondary batteries in series. The secondary battery module of battery pack 2203 has the same functionality as Figure 23A, except for differences in the number of secondary batteries that make up the module, so the explanation is omitted.

[0319] Figure 23E shows a transport vehicle 2005 for transporting cargo as an example. It has an electrically controlled motor and performs various tasks by receiving power from a secondary battery that constitutes the secondary battery module of the battery pack 2204. Furthermore, the transport vehicle 2005 is not limited to being driven and operated by a human; it can also be operated unmanned via CAN communication or the like. Although Figure 23E illustrates a forklift, it is not particularly limited, and a battery pack having a secondary battery according to one aspect of the present invention can be mounted on industrial machinery that can be operated via CAN communication or the like, such as automated transport machines, work robots, or small construction machinery.

[0320] Furthermore, Figure 24A shows an example of an electric bicycle using a secondary battery according to one embodiment of the present invention. The secondary battery according to one embodiment of the present invention can be applied to the electric bicycle 2100 shown in Figure 24A. The energy storage device 2102 shown in Figure 24B includes, for example, a plurality of secondary batteries and a protection circuit.

[0321] The electric bicycle 2100 is equipped with a power storage device 2102. The power storage device 2102 can supply electricity to a motor that assists the rider. The power storage device 2102 is also portable, and Figure 24B shows it detached from the bicycle. The power storage device 2102 also has multiple secondary batteries 2101 according to one aspect of the present invention built in, and the remaining battery level and other information can be displayed on the display unit 2103. The power storage device 2102 also has a control circuit 2104 capable of charging control or abnormality detection of the secondary batteries, as exemplified in one aspect of the present invention. The control circuit 2104 is electrically connected to the positive and negative electrodes of the secondary batteries 2101. A small solid-state secondary battery may also be provided in the control circuit 2104. By providing a small solid-state secondary battery in the control circuit 2104, power can be supplied to hold data in the memory circuit of the control circuit 2104 for a long period of time. Furthermore, a synergistic effect on safety can be obtained by combining it with a secondary battery that uses the positive electrode active material according to one aspect of the present invention as the positive electrode. A secondary battery and control circuit 2104 using a positive electrode active material according to one aspect of the present invention can greatly contribute to eliminating accidents such as fires caused by secondary batteries.

[0322] Figure 24C also shows an example of a motorcycle using a secondary battery according to one embodiment of the present invention. The scooter 2300 shown in Figure 24C is equipped with a power storage device 2302, side mirrors 2301, and turn signals 2303. The power storage device 2302 can supply electricity to the turn signals 2303. Furthermore, the power storage device 2302, which houses multiple secondary batteries using the positive electrode active material according to one embodiment of the present invention as the positive electrode, can have a high capacity and contribute to miniaturization. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery.

[0323] Furthermore, the scooter 2300 shown in Figure 24C can accommodate the power storage device 2302 in the under-seat storage compartment 2304. The power storage device 2302 can be stored in the under-seat storage compartment 2304 even if the under-seat storage compartment 2304 is small.

[0324] [Buildings] Next, an example of implementing a secondary battery according to one aspect of the present invention in a building will be explained with reference to Figure 25.

[0325] The house shown in Figure 25A has a power storage device 2612 having a secondary battery with stable battery characteristics, and a solar panel 2610, using a secondary battery manufacturing method according to one aspect of the present invention. The power storage device 2612 is electrically connected to the solar panel 2610 via wiring 2611, etc. The power storage device 2612 may also be electrically connected to a ground-mounted charging device 2604. The power obtained from the solar panel 2610 can be used to charge the power storage device 2612. The power stored in the power storage device 2612 can be used to charge the secondary battery of the vehicle 2603 via the charging device 2604. The power storage device 2612 is preferably installed in the underfloor space. By installing it in the underfloor space, the space above the floor can be used effectively. Alternatively, the power storage device 2612 may be installed on the floor.

[0326] The electricity stored in the energy storage device 2612 can also be supplied to other electronic devices in the house. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or other reasons, electronic devices can be used by using the energy storage device 2612 as an uninterruptible power supply.

[0327] Figure 25B shows an example of an energy storage device according to one aspect of the present invention. As shown in Figure 25B, a large energy storage device 791 obtained by the secondary battery manufacturing method according to one aspect of the present invention is installed in the underfloor space 796 of the building 799.

[0328] The energy storage device 791 is equipped with a control device 790, which is electrically connected by wiring to the distribution board 703, the energy storage controller 705 (also called the control device), the display unit 706, and the router 709.

[0329] Power is supplied from the commercial power supply 701 to the distribution panel 703 via the service drop connection section 710. Power is also supplied to the distribution panel 703 from the energy storage device 791 and the commercial power supply 701, and the distribution panel 703 supplies the supplied power to the general load 707 and the energy storage system load 708 via outlets (not shown).

[0330] General load 707 is, for example, an electrical device such as a television or a personal computer, and energy storage load 708 is, for example, an electrical device such as a microwave oven, refrigerator, or air conditioner.

[0331] The energy storage controller 705 includes a measurement unit 711, a prediction unit 712, and a planning unit 713. The measurement unit 711 has the function of measuring the amount of electricity consumed by the general load 707 and the energy storage system load 708 during a day (for example, from 0:00 to 24:00). The measurement unit 711 may also have the function of measuring the amount of electricity consumed by the energy storage device 791 and the amount of electricity supplied from the commercial power supply 701. The prediction unit 712 has the function of predicting the amount of electricity demanded by the general load 707 and the energy storage system load 708 during the next day, based on the amount of electricity consumed by the general load 707 and the energy storage system load 708 during the day. The planning unit 713 has the function of planning the charging and discharging of the energy storage device 791 based on the amount of electricity demand predicted by the prediction unit 712.

[0332] The amount of electricity consumed by the general load 707 and the energy storage system load 708, as measured by the measurement unit 711, can be checked on the display unit 706. It can also be checked via the router 709 on electrical equipment such as televisions or personal computers. Furthermore, it can be checked via the router 709 on portable electronic devices such as smartphones or tablets. Additionally, the amount of electricity demand predicted by the forecasting unit 712 for each time period (or hourly) can be checked on the display unit 706, electrical equipment, and portable electronic devices.

[0333] [Electronic equipment] A secondary battery according to one aspect of the present invention can be used, for example, in either or both electronic devices and lighting devices. Examples of electronic devices include mobile phones, smartphones, or notebook computers, portable game consoles, portable music players, digital cameras, and digital video cameras.

[0334] The personal computer 2800 shown in Figure 26A includes a casing 2801, a casing 2802, a display unit 2803, a keyboard 2804, and a pointing device 2805, etc. A secondary battery 2807 is provided inside casing 2801, and a secondary battery 2806 is provided inside casing 2802. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 2807 may be electrically connected to the secondary battery 2807. A touch panel is also applied to the display unit 2803. As shown in Figure 26B, the personal computer 2800 can be used as a tablet terminal by removing casings 2801 and 2802, and using only casing 2802.

[0335] A large secondary battery obtained by the secondary battery manufacturing method according to one aspect of the present invention can be applied to either or both of secondary batteries 2806 and 2807. The shape of the secondary battery obtained by the secondary battery manufacturing method according to one aspect of the present invention can be freely changed by changing the shape of the casing. By shaping secondary batteries 2806 and 2807 to match the shape of the casings 2801 and 2802, for example, the capacity of the secondary battery can be increased, and the operating time of the personal computer 2800 can be extended. In addition, the personal computer 2800 can be made lighter.

[0336] Furthermore, a flexible display is applied to the display unit 2803 of the housing 2802. The secondary battery 2806 is a large secondary battery obtained by the secondary battery manufacturing method according to one aspect of the present invention. In the large secondary battery obtained by the secondary battery manufacturing method according to one aspect of the present invention, by using a flexible film for the outer casing, a bendable secondary battery can be made. As a result, as shown in Figure 26C, the housing 2802 can be folded and used. At this time, as shown in Figure 26C, a part of the display unit 2803 can also be used as a keyboard.

[0337] Furthermore, the housing 2802 can be folded so that the display unit 2803 faces inward, as shown in Figure 26D, or so that the display unit 2803 faces outward, as shown in Figure 26E.

[0338] Figure 27A shows an example of a mobile phone. The mobile phone 7400 includes a display unit 7402 built into the housing 7401, as well as operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. The mobile phone 7400 also has a secondary battery 7407. By using a secondary battery according to one embodiment of the present invention for the secondary battery 7407, a lightweight and long-life mobile phone can be provided. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 7407 may be electrically connected to the secondary battery 7407.

[0339] Figure 27B shows the mobile phone 7400 in a bent state. When the mobile phone 7400 is deformed by an external force and the entire device is bent, the secondary battery 7407 located inside is also bent. Figure 27C shows the state of the bent secondary battery 7407 at that time. The secondary battery 7407 is a thin storage battery. The secondary battery 7407 is fixed in the bent state. The secondary battery 7407 has lead electrodes that are electrically connected to a current collector. For example, the current collector is made of copper foil, and a portion of it is alloyed with gallium to improve the adhesion with the active material layer that is in contact with the current collector, resulting in a configuration that ensures high reliability of the secondary battery 7407 when it is bent.

[0340] Figure 27D shows an example of a bangle-type display device. The portable display device 7100 comprises a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 7104 may be electrically connected to the secondary battery 7104. Figure 27E shows the state of the bent secondary battery 7104. When the secondary battery 7104 is worn on the user's arm in a bent state, the housing deforms, and the curvature of part or all of the secondary battery 7104 changes. The degree of curvature at any point in the curve is expressed as the radius of the corresponding circle, and the reciprocal of the radius of curvature is called the curvature. Specifically, part or all of the main surface of the housing or secondary battery 7104 changes within the range of radius of curvature of 40 mm to 150 mm. High reliability can be maintained if the radius of curvature on the main surface of the secondary battery 7104 is within the range of 40 mm to 150 mm. By using a secondary battery according to one aspect of the present invention in the secondary battery 7104 described above, a lightweight and long-lasting portable display device can be provided.

[0341] Figure 27F shows an example of a wristwatch-type personal information terminal. The personal information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, operation buttons 7205, input / output terminals 7206, and the like.

[0342] The 7200 personal digital assistant (PDCA) can run various applications such as mobile phone calls, email, document viewing and creation, music playback, internet communication, and computer games.

[0343] The display unit 7202 has a curved display surface, allowing it to display information along the curved surface. The display unit 7202 also features a touch sensor, allowing it to be operated by touching the screen with a finger or stylus. For example, touching the icon 7207 displayed on the display unit 7202 can launch an application.

[0344] The operation button 7205 can be assigned various functions, including time setting, power on / off, wireless communication on / off, silent mode activation / deactivation, and power saving mode activation / deactivation. For example, the functions of the operation button 7205 can be freely configured by the operating system built into the personal digital assistant 7200.

[0345] Furthermore, the 7200 portable information terminal is capable of performing standardized short-range wireless communication. For example, it can communicate with a wireless-enabled headset to enable hands-free calling.

[0346] Furthermore, the portable information terminal 7200 is equipped with an input / output terminal 7206, allowing it to directly exchange data with other information terminals via a connector. It can also be charged via the input / output terminal 7206. Note that charging may also be performed wirelessly without using the input / output terminal 7206.

[0347] The display unit 7202 of the portable information terminal 7200 has a secondary battery according to one aspect 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. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. For example, the secondary battery 7104 shown in Figure 27E can be incorporated inside the housing 7201 in a curved state, or inside the band 7203 in a bendable state.

[0348] The portable information terminal 7200 preferably has sensors. Preferably, the sensors include, for example, a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, or an acceleration sensor.

[0349] Figure 27G shows an example of an armband-type display device. The display device 7300 has a display unit 7304 and a secondary battery according to one embodiment of the present invention. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. The display device 7300 may also be equipped with a touch sensor on the display unit 7304 and may function as a portable information terminal.

[0350] The display unit 7304 has a curved display surface, allowing it to display information along the curved surface. Furthermore, the display device 7300 can change its display status via standardized short-range wireless communication.

[0351] Furthermore, the display device 7300 is equipped with input / output terminals, allowing it to directly exchange data with other information terminals via connectors. It can also be charged via the input / output terminals. Note that charging may also be performed wirelessly without using the input / output terminals.

[0352] By using a secondary battery according to one aspect of the present invention as the secondary battery of the display device 7300, a lightweight and long-life display device can be provided.

[0353] Furthermore, an example of mounting a secondary battery with good cycle characteristics in an electronic device, according to one aspect of the present invention, will be explained using Figures 27H, 28, and 29.

[0354] By using a secondary battery according to one embodiment of the present invention as a secondary battery in electronic devices, it is possible to provide lightweight and long-lasting products. Examples of everyday electronic devices include electric toothbrushes, electric shavers, and electric beauty devices. For the secondary batteries in these products, there is a demand for a stick-shaped, small, lightweight, and high-capacity secondary battery that is easy for the user to hold.

[0355] Figure 27H is a perspective view of a device also known as a tobacco-containing smoking device (electronic cigarette). In Figure 27H, the electronic cigarette 7500 consists of an atomizer 7501 including a heating element, a secondary battery 7504 that supplies power to the atomizer, and a cartridge 7502 including a liquid supply bottle or a sensor. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 7504 may be electrically connected to the secondary battery 7504. The secondary battery 7504 shown in Figure 27H has external terminals so that it can be connected to a charging device. Since the secondary battery 7504 is the tip when held, it is desirable that its total length is short and its weight is light. A secondary battery according to one aspect of the present invention has high capacity and good cycle characteristics, so it is possible to provide a small and lightweight electronic cigarette 7500 that can be used for a long time over a long period of time.

[0356] Next, Figures 28A and 28B show an example of a foldable tablet terminal. The tablet terminal 7600 shown in Figures 28A and 28B includes a housing 7630a, a housing 7630b, a movable part 7640 connecting housings 7630a and 7630b, a display unit 7631 having display units 7631a and 7631b, switches 7625 to 7627, a fastener 7629, and an operation switch 7628. By using a flexible panel for the display unit 7631, a tablet terminal with a larger display area can be created. Figure 28A shows the tablet terminal 7600 in an open state, and Figure 28B shows the tablet terminal 7600 in a closed state.

[0357] Furthermore, the tablet terminal 7600 has a power storage unit 7635 inside the housings 7630a and 7630b. The power storage unit 7635 is provided across the housings 7630a and 7630b, passing through the movable part 7640.

[0358] The display unit 7631 can have all or part of its area designated as a touch panel area, and data can be entered by touching images, characters, input forms, etc., including icons, displayed in that area. For example, keyboard buttons may be displayed on the entire surface of the display unit 7631a on the housing 7630a side, and information such as characters and images may be displayed on the display unit 7631b on the housing 7630b side.

[0359] Alternatively, the display unit 7631b on the housing 7630b may be used to display a keyboard, while the display unit 7631a on the housing 7630a may be used to display information such as characters and images. Alternatively, the display unit 7631 may be used to display a touch panel keyboard display switching button, so that the keyboard is displayed on the display unit 7631 when the button is touched with a finger or stylus.

[0360] Furthermore, it is possible to simultaneously input touch input to the touch panel area of ​​the display unit 7631a on the housing 7630a and the touch panel area of ​​the display unit 7631b on the housing 7630b.

[0361] Furthermore, switches 7625 to 7627 may not only serve as an interface for operating the tablet terminal 7600, but also as an interface for switching various functions. For example, at least one of switches 7625 to 7627 may function as a switch to turn the tablet terminal 7600 on and off. Also, for example, at least one of switches 7625 to 7627 may have a function to switch the display orientation, such as portrait or landscape, or a function to switch between monochrome or color display. Also, for example, at least one of switches 7625 to 7627 may have a function to adjust the brightness of the display unit 7631. The brightness of the display unit 7631 can be optimized according to the amount of ambient light during use, as detected by the light sensor built into the tablet terminal 7600. Note that the tablet terminal may incorporate other detection devices in addition to the light sensor, such as a gyroscope, accelerometer, or other tilt detection sensors.

[0362] Furthermore, while Figure 28A shows an example where the display area of ​​the display unit 7631a on the housing 7630a side and the display unit 7631b on the housing 7630b side are approximately the same, the display areas of the display units 7631a and 7631b are not particularly limited, and the size of one may differ from the other, and the display quality may also differ. For example, one display panel may be capable of displaying a higher resolution than the other.

[0363] Figure 28B shows the tablet terminal 7600 in a folded state. The tablet terminal 7600 includes a housing 7630, a solar cell 7633, and a charge / discharge control circuit 7634 including a DC-DC converter 7636. Furthermore, a secondary battery according to one embodiment of the present invention is used as the energy storage body 7635.

[0364] As mentioned above, the tablet terminal 7600 is foldable, so when not in use, the casings 7630a and 7630b can be folded together. Folding protects the display unit 7631, thereby increasing the durability of the tablet terminal 7600. Furthermore, since the energy storage unit 7635 using a secondary battery according to one embodiment of the present invention has high capacity and good cycle characteristics, it is possible to provide a tablet terminal 7600 that can be used for a long period of time over a long period of time. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery in the energy storage unit 7635 may be electrically connected to the secondary battery.

[0365] In addition, the tablet terminal 7600 shown in Figures 28A and 28B may have functions such as displaying various information (still images, videos, text images, etc.), displaying a calendar, date, or time on the display unit, a touch input function for touch input operation or editing of information displayed on the display unit, and a function for controlling processing by various software (programs).

[0366] The solar cell 7633 mounted on the surface of the tablet terminal 7600 can supply power to the touch panel, display unit, or video signal processing unit, etc. The solar cell 7633 can be installed on one or both sides of the housing 7630, allowing for an efficient configuration of charging the energy storage unit 7635. Using a lithium-ion battery as the energy storage unit 7635 offers advantages such as miniaturization.

[0367] Furthermore, the configuration and operation of the charge / discharge control circuit 7634 shown in Figure 28B will be explained with a block diagram in Figure 28C. Figure 28C shows the solar cell 7633, energy storage unit 7635, DC-DC converter 7636, converter 7637, switches SW1 to SW3, and display unit 7631. The energy storage unit 7635, DC-DC converter 7636, converter 7637, and switches SW1 to SW3 correspond to the charge / discharge control circuit 7634 shown in Figure 28B.

[0368] First, let's explain an example of operation when electricity is generated by the solar cell 7633 using ambient light. The power generated by the solar cell is boosted or stepped down by the DC-DC converter 7636 to obtain a voltage suitable for charging the energy storage unit 7635. When power from the solar cell 7633 is used to operate the display unit 7631, switch SW1 is turned on, and the converter 7637 boosts or steps down the voltage to the voltage required by the display unit 7631. When the display unit 7631 is not being used, switch SW1 is turned off, and switch SW2 is turned on to charge the energy storage unit 7635.

[0369] The solar cell 7633 is shown as an example of a power generation method, but it is not particularly limited, and the storage unit 7635 may be charged by other power generation methods such as piezoelectric elements or thermoelectric elements (Peltier elements). For example, a contactless power transmission module that transmits and receives power wirelessly (non-contact) to charge the storage unit, or a combination of other charging methods may be used.

[0370] Figure 29 shows an example of another electronic device. In Figure 29, the display device 8000 is an example of an electronic device using a secondary battery 8004 according to one aspect of the present invention. Specifically, the display device 8000 corresponds to a display device for receiving TV broadcasts and has a housing 8001, a display unit 8002, a speaker unit 8003, a secondary battery 8004, etc. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 8004 may be electrically connected to the secondary battery 8004. The secondary battery 8004 according to one aspect of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power source or use power stored in the secondary battery 8004. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the display device 8000 can be used by using the secondary battery 8004 according to one aspect of the present invention as an uninterruptible power supply.

[0371] The display unit 8002 can use semiconductor display devices such as liquid crystal displays, light-emitting devices equipped with light-emitting elements such as organic EL elements in each pixel, electrophoretic displays, DMDs (Digital Micromirror Devices), PDPs (Plasma Display Panels), and FEDs (Field Emission Displays).

[0372] Furthermore, the term "display device" includes all information display devices, such as those for receiving TV broadcasts, personal computers, and advertising displays.

[0373] In Figure 29, the fixed-type lighting device 8100 is an example of an electronic device using a secondary battery 8103 according to one aspect of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a secondary battery 8103, etc. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 8103 may be electrically connected to the secondary battery 8103. In Figure 29, the case in which the secondary battery 8103 is installed inside the ceiling 8104 on which the housing 8101 and light source 8102 are installed is illustrated, but the secondary battery 8103 may also be installed inside the housing 8101. The lighting device 8100 can receive power from a commercial power source or use power stored in the secondary battery 8103. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the lighting device 8100 can be used by using the secondary battery 8103 according to one aspect of the present invention as an uninterruptible power supply.

[0374] Although Figure 29 illustrates a fixed lighting device 8100 installed on the ceiling 8104, the secondary battery according to one aspect of the present invention can also be used in fixed lighting devices installed on surfaces other than the ceiling 8104, such as the side wall 8105, floor 8106, window 8107, etc., or in tabletop lighting devices, etc.

[0375] Furthermore, the light source 8102 can be an artificial light source that artificially generates light using electricity. Specifically, examples of the above artificial light sources include incandescent light bulbs, discharge lamps such as fluorescent lamps, LEDs, and / or light-emitting elements such as organic EL elements.

[0376] In Figure 29, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using a secondary battery 8203 according to one aspect of the present invention. Specifically, the indoor unit 8200 has a housing 8201, an air outlet 8202, a secondary battery 8203, etc. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 8203 may be electrically connected to the secondary battery 8203. In Figure 29, the case in which the secondary battery 8203 is provided in the indoor unit 8200 is illustrated, but the secondary battery 8203 may also be provided in the outdoor unit 8204. Alternatively, the secondary battery 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power source or it can use power stored in the secondary battery 8203. In particular, when both the indoor unit 8200 and the outdoor unit 8204 are equipped with secondary batteries 8203, even when power cannot be supplied from the commercial power source due to a power outage or the like, the air conditioner can be used by using the secondary battery 8203 according to one aspect of the present invention as an uninterruptible power supply.

[0377] Although Figure 29 illustrates a separate-type air conditioner consisting of an indoor unit and an outdoor unit, the secondary battery according to one aspect of the present invention can also be used in an integrated-type air conditioner that has the functions of both the indoor and outdoor units in a single housing.

[0378] In Figure 29, the electric refrigerator-freezer 8300 is an example of an electronic device using a secondary battery 8304 according to one aspect of the present invention. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, etc. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 8304 may be electrically connected to the secondary battery 8304. In Figure 29, the secondary battery 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 can receive power from a commercial power source or use power stored in the secondary battery 8304. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the electric refrigerator-freezer 8300 can be used by using the secondary battery 8304 according to one aspect of the present invention as an uninterruptible power supply.

[0379] Furthermore, among the electronic devices mentioned above, high-frequency heating devices such as microwave ovens and electric rice cookers require high power in a short period of time. Therefore, by using a secondary battery according to one aspect of the present invention as an auxiliary power source to supplement the power that cannot be supplied by the commercial power supply, it is possible to prevent the commercial power supply circuit breaker from tripping when the electronic device is in use.

[0380] Furthermore, by storing power in the secondary battery during periods when electronic devices are not in use, particularly during periods when the proportion of the total amount of power supplied by the commercial power source that is actually used (referred to as the power usage rate) is low, it is possible to suppress the increase in the power usage rate outside of these periods. For example, in the case of the electric refrigerator-freezer 8300, power is stored in the secondary battery 8304 at night when the temperature is low and the refrigerator door 8302 and freezer door 8303 are not opened or closed. Then, during the daytime when the temperature is high and the refrigerator door 8302 and freezer door 8303 are opened and closed, the secondary battery 8304 can be used as an auxiliary power source, thereby keeping the daytime power usage rate low.

[0381] According to one aspect of the present invention, the cycle characteristics of a secondary battery can be improved, thereby enhancing its reliability. Furthermore, according to one aspect of the present invention, a high-capacity secondary battery can be created, thereby improving the characteristics of the secondary battery and thus making the secondary battery itself smaller and lighter. Therefore, by incorporating a secondary battery according to one aspect of the present invention into the electronic device described in this embodiment, it is possible to create an electronic device that has a longer lifespan and is lighter.

[0382] Figure 30A shows an example of a wearable device. Wearable devices use rechargeable batteries as a power source. Furthermore, in order to enhance splash resistance, water resistance, or dust resistance when used by users in daily life or outdoors, there is a demand for wearable devices that can be charged wirelessly in addition to wired charging with exposed connectors.

[0383] For example, a secondary battery according to one aspect of the present invention can be mounted in a spectacle-type device 9000 as shown in Figure 30A. The spectacle-type device 9000 has a frame 9000a and a display unit 9000b. By mounting the secondary battery in the temple portion of the curved frame 9000a, a lightweight spectacle-type device 9000 can be made with good weight balance and a long continuous usage time. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0384] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the headset-type device 9001. The headset-type device 9001 has at least a microphone section 9001a, a flexible pipe 9001b, and an earphone section 9001c. The secondary battery can be provided in the flexible pipe 9001b or in the earphone section 9001c. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0385] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in a device 9002 that can be directly attached to the body. The secondary battery 9002b can be provided within the thin housing 9002a of the device 9002. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 9002b may be electrically connected to the secondary battery 9002b. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to the miniaturization of the housing can be realized.

[0386] Furthermore, a secondary battery according to one aspect of the present invention can be mounted on a device 9003 that can be attached to clothing. The secondary battery 9003b can be provided within the thin housing 9003a of the device 9003. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 9003b may be electrically connected to the secondary battery 9003b. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to the miniaturization of the housing can be realized.

[0387] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the belt-type device 9006. The belt-type device 9006 has a belt portion 9006a and a wireless power supply / receiving portion 9006b, and a secondary battery can be mounted inside the belt portion 9006a. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to the miniaturization of the housing can be realized.

[0388] Furthermore, a secondary battery according to one aspect of the present invention can be mounted in the wristwatch-type device 9005. The wristwatch-type device 9005 has a display unit 9005a and a belt unit 9005b, and the secondary battery can be provided in either the display unit 9005a or the belt unit 9005b. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery may be electrically connected to the secondary battery. By incorporating a secondary battery according to one aspect of the present invention, a configuration that can accommodate space saving due to miniaturization of the housing can be realized.

[0389] The display unit 9005a can display not only the time, but also various other information such as incoming emails and / or phone calls.

[0390] Furthermore, since the wristwatch-type device 9005 is a wearable device that is worn directly on the wrist, it may be equipped with sensors to measure the user's pulse, blood pressure, etc. It can accumulate data on the user's exercise level and health, and manage their health.

[0391] Figure 30B shows a perspective view of the wristwatch-type device 9005 after it has been removed from the arm.

[0392] A side view is also shown in Figure 30C. Figure 30C shows a secondary battery 913 according to one embodiment of the present invention built inside. The secondary battery 913 is located in a position overlapping with the display unit 9005a, and is small and lightweight.

[0393] Figure 31A shows an example of a cleaning robot. The cleaning robot 9300 has a display unit 9302 located on the top surface of the housing 9301, multiple cameras 9303 located on the sides, a brush 9304, operation buttons 9305, a secondary battery 9306, and various sensors. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 9306 may be electrically connected to the secondary battery 9306. Although not shown, the cleaning robot 9300 is equipped with wheels, a suction port, etc. The cleaning robot 9300 is self-propelled, can detect dirt 9310, and can suck up the dirt from a suction port located on the bottom surface.

[0394] For example, the cleaning robot 9300 can analyze images captured by the camera 9303 to determine the presence or absence of obstacles such as walls, furniture, or steps. Furthermore, if the image analysis detects an object that could become entangled in the brush 9304, such as wiring, the rotation of the brush 9304 can be stopped. The cleaning robot 9300 is equipped with a secondary battery 9306 according to one aspect of the present invention and a semiconductor device or electronic component. By using the secondary battery 9306 according to one aspect of the present invention in the cleaning robot 9300, the cleaning robot 9300 can be made into a highly reliable electronic device with a long operating time.

[0395] Figure 31B shows an example of a robot. The robot 9400 shown in Figure 31B includes a secondary battery 9409, an illuminance sensor 9401, a microphone 9402, an upper camera 9403, a speaker 9404, a display unit 9405, a lower camera 9406, an obstacle sensor 9407, a movement mechanism 9408, a computing device, etc. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 9409 may be electrically connected to the secondary battery 9409.

[0396] Microphone 9402 has the function of detecting the user's voice and ambient sounds. Speaker 9404 has the function of emitting sound. Robot 9400 can communicate with the user using microphone 9402 and speaker 9404.

[0397] The display unit 9405 has the function of displaying various types of information. The robot 9400 can display the user's desired information on the display unit 9405. The display unit 9405 may be equipped with a touch panel. The display unit 9405 may also be a detachable information terminal, and by installing it in a fixed position on the robot 9400, charging and data transfer can be made possible.

[0398] The upper camera 9403 and lower camera 9406 have the function of imaging the area around the robot 9400. In addition, the obstacle sensor 9407 can detect the presence or absence of obstacles in the direction of travel when the robot 9400 moves forward using the movement mechanism 9408. The robot 9400 can recognize its surrounding environment and move safely using the upper camera 9403, lower camera 9406 and obstacle sensor 9407.

[0399] The robot 9400 is equipped with a secondary battery 9409 according to one aspect of the present invention and a semiconductor device or electronic components inside. By using the secondary battery according to one aspect of the present invention in the robot 9400, the robot 9400 can be made into an electronic device with a long operating time and high reliability.

[0400] Figure 31C shows an example of an aircraft. The aircraft 9500 shown in Figure 31C has a propeller 9501, a camera 9502, and a secondary battery 9503, and has the capability to fly autonomously. To enhance safety, a protection circuit to prevent overcharging and / or over-discharging of the secondary battery 9503 may be electrically connected to the secondary battery 9503.

[0401] For example, image data captured by camera 9502 is stored in electronic component 9504. Electronic component 9504 can analyze the image data and detect the presence or absence of obstacles during movement. Furthermore, electronic component 9504 can estimate the remaining battery level from the change in the storage capacity of secondary battery 9503. The aircraft 9500 is equipped with a secondary battery 9503 according to one aspect of the present invention. By using a secondary battery according to one aspect of the present invention in the aircraft 9500, the aircraft 9500 can be made into an electronic device with a long operating time and high reliability.

[0402] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0403] In this example, to confirm whether the ceramic material traps cobalt ions, the powdered ceramic material was stirred in a cobalt solution, and the concentration of the cobalt solution was measured.

[0404] First, to mix the organic solvent, Li-TFSI was added to an EC:DEC = 3:7 (volume ratio) (manufactured by Kishida Chemical Co., Ltd.) in a glove box under an argon atmosphere to a concentration of 1 mol / L, and the mixture was stirred at room temperature for approximately 18 hours.

[0405] Next, in a glove box under an argon atmosphere, sample cells were prepared: one containing Li metal immersed in an organic solvent, and the other containing cobalt foil immersed in an organic solvent. The two cells were connected, and a glass filter was placed between them. Lithium-ion conductive glass ceramics (LICGC) manufactured by Ohara Corporation were used as the glass filter. The glass filter was installed to prevent the products generated by electrolysis from being reduced on the counter electrode side. A DC voltage of 3.6V was applied between the Li metal and the cobalt foil for 20 hours, and approximately 15 mL of a cobalt solution of approximately 50 ppm was prepared.

[0406] Next, cobalt solution was added to each ceramic material and stirred. Specifically, a stirring bar was placed in each of six 5 mL sample vials, and then approximately 30 mg each of magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), alumina (Al2O3), boehmite (AlOOH), rutile-type titanium dioxide (TiO2), and anatase-type titanium dioxide were placed in separate sample vials. These sample vials were placed in a glove box, 2 mL of cobalt solution was added to each vial, and the mixture was stirred at room temperature and 300 rpm for approximately 16 hours.

[0407] After stirring, the sample bottle was removed from the glove box. The stirred suspension was filtered using a membrane filter to separate it into a cobalt solution (filtrate) and a ceramic material (filtrate).

[0408] The cobalt concentration in the cobalt solution separated from each ceramic material was measured using an atomic absorption spectrometer (Analytic Jena, ContrAA600). Each measurement was performed twice for the separated cobalt solution from each ceramic material, and the average value was calculated. The measurement results are shown in Figure 32.

[0409] The obtained cobalt concentrations were as follows: For the MgO sample, the first measurement was 32.55 ppm, the second measurement was 30.82 ppm, and the average was 31.69 ppm. For the Mg(OH)2 sample, the first measurement was 23.40 ppm, the second measurement was 26.72 ppm, and the average was 25.06 ppm. For the Al2O3 sample, the first measurement was 37.63 ppm, the second measurement was 40.27 ppm, and the average was 38.95 ppm. For the AlOOH sample, the first measurement was 40.20 ppm, the second measurement was 43.18 ppm, and the average was 41.69 ppm. For the rutile-type TiO2 sample, the first measurement was 36.56 ppm, the second measurement was 34.59 ppm, and the average was 35.58 ppm. For the anatase-type TiO2 sample, the first measurement was 31.05 ppm, the second measurement was 31.07 ppm, and the average was 31.06 ppm. As a comparative example, for a cobalt solution without added ceramic material, the first measurement was 40.65 ppm, the second measurement was 41.40 ppm, and the average was 41.03 ppm. For a filtered sample of the cobalt solution without added ceramic material, the first measurement was 42.97 ppm, the second measurement was 42.40 ppm, and the average was 42.69 ppm.

[0410] The above measurement results indicate that the cobalt concentration in the filtered Mg(OH)2 sample is low. This suggests that Mg(OH)2 may be trapping cobalt ions. [Examples]

[0411] In this example, a polypropylene separator coated with an MgO layer was prepared. The preparation method is as follows.

[0412] First, 2 g of MgO and 0.96296 g of NMP were mixed in a kneader (Sinky Co., Ltd., rotation-orbit type mixer Awatori Rentaro) at 2000 rpm for 3 minutes. Mixing MgO and NMP first dispersed the MgO. To the resulting mixture, 0.2 g of NMP solution containing 5 wt% PVdF was added and mixed in the kneader. Subsequently, 4.24444 g of NMP solution containing 5 wt% PVdF was added to the resulting mixture and mixed in the kneader. The PVdF was added gradually to prevent aggregation of PVdF. Through the above steps, a slurry with a solid content ratio of 30% (MgO:PVdF=90:10) was prepared.

[0413] Next, the slurry was applied onto a 20 μm thick polypropylene separator using a coating device (applicator). At this time, the distance between the coating part (blade) of the coating device and the coating surface (surface of the polypropylene separator) was set to 40 μm, and the coating speed was set to 10 mm / sec.

[0414] The polypropylene separator coated with the above slurry was dried in a ventilated drying oven at 80°C for 30 minutes.

[0415] The thickness of the MgO layer in the polypropylene separator coated with the MgO layer obtained through the above process was measured using a micrometer. The thickness of the MgO-coated separator was 45 μm to 60 μm, and the thickness of the polypropylene separator was 20 μm. Therefore, the thickness of the MgO layer was approximately 25 μm to 40 μm. [Examples]

[0416] In this example, a polypropylene separator coated with two Mg(OH) layers was prepared. The preparation method is as follows.

[0417] First, 2 g of Mg(OH)2 and 2 g of NMP were mixed at 2000 rpm for 3 minutes in a kneader (Sinky Co., Ltd., Awatori Rentaro, a rotation-and-revolution type mixer). The average particle size of the Mg(OH)2 particles used was approximately 7 μm. A laser diffraction particle size distribution analyzer (Shimadzu Corporation, SALD-2200) was used to measure the average particle size of the Mg(OH)2 particles. The Mg(OH)2 was dispersed by first mixing it with NMP. 0.2 g of NMP solution containing 5 wt% PVdF was added to the resulting mixture and mixed in the kneader. Subsequently, 4.24444 g of NMP solution containing 5 wt% PVdF was added to the resulting mixture and mixed in the kneader. The PVdF was added gradually to prevent aggregation of the PVdF. Through the above process, a slurry with a solid content ratio of 26% (Mg(OH)2:PVdF=90:10) was prepared.

[0418] Next, the slurry was applied onto a 20 μm thick polypropylene separator using a coating device (applicator). At this time, the distance between the coating part (blade) of the coating device and the coating surface (surface of the polypropylene separator) was set to 30 μm, and the coating speed was set to 10 mm / sec.

[0419] The polypropylene separator coated with the above slurry was dried in a ventilated drying oven at 80°C for 30 minutes.

[0420] The film thickness of the Mg(OH)2 layer was measured using a micrometer on the separators coated with the Mg(OH)2 layer obtained through the above process. The film thickness of the Mg(OH)2 layer-coated separator was 70 μm to 80 μm, and the film thickness of the polypropylene separator was 20 μm. Therefore, the film thickness of the Mg(OH)2 layer was 50 μm to 60 μm.

[0421] The density of the Mg(OH)2 layer was determined as follows. First, a polypropylene separator coated with an Mg(OH)2 layer and a polypropylene separator not coated with an Mg(OH)2 layer were punched out in a circle with a diameter of 18 mm, and their weight and film thickness were measured. The weight and film thickness of the polypropylene separator coated with an Mg(OH)2 layer were 9.271 mg and 75 μm, respectively, while the weight and film thickness of the polypropylene separator alone were 3.536 mg and 20 μm, respectively. Therefore, the weight and film thickness of the Mg(OH)2 layer are 5.735 mg and 55 μm, respectively. The calculated weight and film thickness of the Mg(OH)2 layer are compared with the area of ​​the 18 mm diameter circle, which is 2.5434 cm². 2 Substituting the values ​​into the formula density = weight ÷ film thickness ÷ area, the density of the Mg(OH) 2 layer was calculated to be approximately 410 mg / cm³. 3 That was the case.

[0422] The porosity of the Mg(OH)2 layer is calculated by subtracting the value obtained by dividing the density of the Mg(OH)2 layer by the density of the Mg(OH)2 layer when the porosity is 0 from 1. The density of the Mg(OH)2 layer when the porosity is 0 is calculated by considering that the material densities of Mg(OH)2 and PVdF are both 2360 mg / cm³. 3 , 1780 mg / cm³ 3 Therefore, 2300 mg / cm³ 3 Therefore, the porosity of the Mg(OH)2 layer was approximately 82.2% by volume. [Explanation of symbols]

[0423] 102: Heating furnace interior space, 104: Heating plate, 106: Heater section, 108: Insulation material, 116: Container, 118: Lid, 119: Space, 120: Heating furnace, 130: Laminate, 131: Laminate, 500: Secondary battery, 501: Positive electrode current collector, 502a: Region, 502: Positive electrode active material layer, 503: Positive electrode, 504: Negative electrode current collector, 505a: Region, 505: Negative electrode active material layer, 506: Negative electrode, 507a: Region, 507b: Region, 507: Separator, 508: Electrolyte, 509a: Outer casing, 509b: Outer casing, 509: Outer casing, 510: Positive electrode lead electrode, 511: Negative electrode lead electrode, 512 :Laminate, 513:Resin layer, 514:Region, 515a:Electrolyte, 515b:Electrolyte, 515c:Electrolyte, 516:Inlet, 521a:Region, 521b:Region, 521:Porous polymer membrane, 522:Layer, 550:Laminate, 553:Acetylene black, 554:Graphene, 556:Acetylene black, 557:Graphene, 560:Secondary battery, 561:Positive electrode active material, 563:Negative electrode active material, 570:Manufacturing equipment, 571:Material input chamber, 572:Transportation chamber, 573:Processing chamber, 576:Material removal chamber, 580:Transportation mechanism, 581:Polymer membrane, 582:Pore, 58 4: Polymer film, 585: Hole, 591: Stage, 594: Nozzle, 600: Secondary battery, 701: Commercial power supply, 703: Distribution board, 705: Energy storage controller, 706: Display unit, 707: General load, 708: Energy storage system load, 709: Router, 710: Service drop connection section, 711: Measurement section, 712: Prediction section, 713: Planning section, 790: Control device, 791: Energy storage device, 796: Underfloor space section, 799: Building, 801: Composite oxide, 802: Fluoride, 803: Compound, 804: Mixture, 808: Cobalt-containing material, 911a: Terminal, 911b: Terminal, 913: Secondary battery , 930a: Housing, 930b: Housing, 930: Housing, 931a: Negative electrode active material layer, 931: Negative electrode, 932a: Positive electrode active material layer, 932: Positive electrode, 933: Separator, 950a: Winding body, 950: Winding body, 951: Terminal, 952: Terminal, 970: Secondary battery, 971: Housing, 972: Laminate, 973a: Positive electrode lead electrode, 973b: Terminal, 973c: Conductor, 974a: Negative electrode lead electrode, 974b: Terminal, 974c: Conductor, 975a: Positive electrode, 975b: Positive electrode, 976: Separator, 977a: Negative electrode, 1301a: First battery, 1301b: First battery,1302: Battery controller, 1303: Motor controller, 1304: Motor, 1305: Gear, 1306: DC-DC circuit, 1307: Electric power steering, 1308: Heater, 1309: Defogger, 1310: DC-DC circuit, 1311: Second battery, 1312: Inverter, 1313: Audio, 1314: Power windows, 1315: Lights, 1316: Tires, 1317: Rear motor, 1320: Control circuit section, 1321: Control circuit section, 1322: Control circuit, 1324: Switch section, 1325: External terminals, 1326: External terminals, 1 415: Battery pack, 1421: Wiring, 1422: Wiring, 2001: Automobile, 2002: Transport vehicle, 2003: Transport vehicle, 2004: Aircraft, 2005: Transport vehicle, 2100: Electric bicycle, 2101: Secondary battery, 2102: Energy storage device, 2103: Display unit, 2104: Control circuit, 2201: Battery pack, 2202: Battery pack, 2203: Battery pack, 2204: Battery pack, 2300: Scooter, 2301: Side mirror, 2302: Energy storage device, 2303: Turn signal light, 2304: Under-seat storage, 2603: Vehicle, 2604: Charging device, 2610: Solar Panel, 2611: Wiring, 2612: Energy storage device, 2800: Personal computer, 2801: Enclosure, 2802: Enclosure, 2803: Display unit, 2804: Keyboard, 2805: Pointing device, 2806: Secondary battery, 2807: Secondary battery, 7100: Portable display device, 7101: Enclosure, 7102: Display unit, 7103: Operation buttons, 7104: Secondary battery, 7200: Portable information terminal, 7201: Enclosure, 7202: Display unit, 7203: Band, 7204: Buckle, 7205: Operation buttons, 7206: Input / output terminal, 7207: Icon, 7300: Front Display device, 7304: Display unit, 7400: Mobile phone, 7401: Housing, 7402: Display unit, 7403: Operation buttons, 7404: External connection port, 7405: Speaker, 7406: Microphone, 7407: Rechargeable battery, 7500: Electronic cigarette, 7501: Atomizer, 7502: Cartridge, 7504: Rechargeable battery, 7600: Tablet terminal, 7625: Switch, 7627: Switch, 7628: Operation switch, 7629: Fastener, 7630a: Housing, 7630b: Housing, 7630: Housing, 7631a: Display unit, 7631b: Display unit, 7631: Display unit,7633: Solar cell, 7634: Charge / discharge control circuit, 7635: Energy storage unit, 7636: DC-DC converter, 7637: Converter, 7640: Movable part, 8000: Display device, 8001: Housing, 8002: Display unit, 8003: Speaker unit, 8004: Secondary battery, 8100: Lighting device, 8101: Housing, 8102: Light source, 8103: Secondary battery, 8104: Ceiling, 8105: Side wall, 8106: Floor, 8107: Window, 820 0: Indoor unit, 8201: Housing, 8202: Air outlet, 8203: Rechargeable battery, 8204: Outdoor unit, 8300: Electric refrigerator / freezer, 8301: Housing, 8302: Door for refrigerator compartment, 8303: Door for freezer compartment, 8304: Rechargeable battery, 9000a: Frame, 9000b: Display unit, 9000: Glasses-type device, 9001a: Microphone unit, 9001b: Flexible pipe, 9001c: Earphone unit, 9001: Headset-type device 9002a: Housing, 9002b: Rechargeable battery, 9002: Device, 9003a: Housing, 9003b: Rechargeable battery, 9003: Device, 9005a: Display unit, 9005b: Belt unit, 9005: Wristwatch-type device, 9006a: Belt unit, 9006b: Wireless power supply / receiving unit, 9006: Belt-type device, 9300: Cleaning robot, 9301: Housing, 9302: Display unit, 9303: Camera, 9304: Brush 9305: Operation button, 9306: Rechargeable battery, 9310: Trash, 9400: Robot, 9401: Illuminance sensor, 9402: Microphone, 9403: Upper camera, 9404: Speaker, 9405: Display unit, 9406: Lower camera, 9407: Obstacle sensor, 9408: Movement mechanism, 9409: Rechargeable battery, 9500: Flying body, 9501: Propeller, 9502: Camera, 9503: Rechargeable battery, 9504: Electronic component,

Claims

1. A separator comprising a polymer porous film and a layer having a ceramic material containing metal oxide nanoparticles, The thickness of the layer having the ceramic material is 1 μm or more and 100 μm or less. The thickness of the polymer porous film is 4 μm or more and 50 μm or less. A separator comprising magnesium hydroxide in the aforementioned metal oxide fine particles.

2. A separator according to claim 1, wherein the average particle size of the metal oxide fine particles is 0.01 μm or more and 50 μm or less.

3. A separator according to claim 1 or claim 2, wherein the layer having the ceramic material is in contact with one surface of the polymer porous film.

4. A separator comprising a polymer porous film and a layer having multiple ceramic materials containing metal oxide nanoparticles, The layers having the plurality of ceramic materials are positioned so as to sandwich the polymer porous film, The thickness of the layer having the ceramic material is 1 μm or more and 100 μm or less. The thickness of the polymer porous film is 4 μm or more and 50 μm or less. A separator comprising magnesium hydroxide in the aforementioned metal oxide fine particles.

5. A separator according to claim 4, wherein the average particle size of the metal oxide fine particles is 0.01 μm or more and 50 μm or less.

6. A separator according to claim 4 or claim 5, wherein the layer having the ceramic material is in contact with one surface of the polymer porous film.

7. A secondary battery comprising a positive electrode, a negative electrode, a separator according to any one of claims 1 to 6 sandwiched between the positive electrode and the negative electrode, and an electrolyte.

8. A secondary battery according to claim 7, wherein the electrolyte is disposed inside the pores of the polymer porous membrane.

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