Method for producing a positive electrode active material and a lithium ion battery

Abstract

To provide a composite oxide having a high lithium diffusion rate, or to provide a lithium-containing composite phosphate having a high lithium diffusion rate, or to provide a positive electrode active material having a high lithium diffusion rate, or to provide a lithium ion battery having a high output, or to provide a low-cost lithium ion battery. [Solution] The positive electrode active material is produced by the following steps: a first step of mixing a lithium compound, a phosphorus compound, and water; a second step of adding a first aqueous solution to the first mixed liquid formed by the first step to adjust the pH; a third step of mixing an iron compound with the second mixed liquid formed by the second step; and a fourth step of heat treating the third mixed liquid formed by the third step, which has a pH of 3.5 to 5.0, at a pressure of 0.1 MPa to 2 MPa and a maximum temperature of more than 100°C and not more than 119°C.

Description

[Technical field]

[0001] The present invention relates to an article, a method, or a manufacturing method. The present invention relates to a method, manufacture, or composition of matter. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, or any of these devices. In particular, the present invention relates to a driving method thereof, a manufacturing method thereof, or an evaluation method thereof. The present invention relates to a power storage device, a manufacturing method thereof, or an evaluation method thereof. The present invention relates to a lithium-containing composite phosphate and a method for producing the same. The present invention relates to a lithium ion battery and a method for producing the same. The present invention relates to a battery control unit and an electronic device. [Background technology]

[0002] In a solution under high temperature and pressure, the solubility can be increased compared to that under normal temperature and pressure. In addition, the dissolution and precipitation of materials can be controlled by adjusting the pH of the solution ( Patent Document 1). Hydrothermal methods are examples of reactions under high temperature and pressure.

[0003] In recent years, the development of power storage devices such as lithium-ion secondary batteries has been progressing. For example, a battery using LiFePO4 (lithium iron phosphate), a composite oxide, as the active material A power storage device having electrodes using LiFePO4 is a thermal storage device. It has high stability and good cycle characteristics.

[0004] As a method for producing a composite oxide such as LiFePO4, for example, a hydrothermal method is used (particularly Permitted document 2).

[0005] By using the hydrothermal method, even a material that is hardly soluble in water at normal temperature and pressure can be dissolved, so that synthesis of substances that cannot be obtained by production methods at normal temperature and pressure, or crystal growth can be carried out. Also, by using the hydrothermal method, fine particles of single crystals in the target substance can be easily synthesized.

[0006] In the hydrothermal method, for example, a solution containing raw materials is placed in a pressure-resistant container and subjected to treatment by pressurization and heating, and then the desired compound can be synthesized by filtering the solution that has been subjected to treatment by pressurization and heating.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] One aspect of the present invention is to provide a composite oxide having a high lithium diffusion rate as one of the problems. Or, one aspect of the present invention is to provide a lithium-containing composite phosphate having a high lithium diffusion rate as one of the problems. Or, one aspect of the present invention is to provide a positive electrode active material having a high lithium diffusion rate as one of the problems. Or, one aspect of the present invention is to provide a lithium-ion battery with high output as one of the problems. Or, one aspect of the present invention is to provide a lithium-ion battery with low cost as one of the problems. Or, ​​​​​One aspect of the present invention aims to provide a novel battery.

[0009] Note that the description of these problems does not prevent the existence of other problems. In addition, one aspect of the present invention does not necessarily need to solve all of these problems. Note that other problems will become apparent from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc.

Means for Solving the Problems

[0010] One aspect of the present invention is a method for producing a positive electrode active material having lithium, phosphorus, iron, and oxygen, which includes a first step of mixing a lithium compound, a phosphorus compound, and water, and a second step of adding a first aqueous solution to the first mixed solution formed in the first step to adjust the pH, a third step of mixing an iron compound into the second mixed solution formed in the second step, and a fourth step of performing heat treatment on the third mixed solution formed in the third step under a pressure of 0.1 MPa or more and 2 MPa a or less. The pH of the third mixed solution is 3. 5 or more and 5.0 or less, and the maximum temperature in the fourth step is greater than 100 °C and 119 °C or less. The positive electrode active material is a method for producing a positive electrode active material belonging to the space group Pnma. 5 or more and 5.0 or less, and the maximum temperature in the fourth step is greater than 100 °C and 119 °C or less. The positive electrode active material is a method for producing a positive electrode active material belonging to the space group Pnma.

[0011] In addition, in the above configuration, the lithium compound is lithium chloride, the first aqueous solution is alkaline, and the base contained in the first aqueous solution is preferably ammonia or an organic amine.

[0012] In addition, in the above configuration, the third step is preferably performed in an air atmosphere. .​

[0013] Also, in the above configuration, the positive electrode active material preferably comprises particles having a thickness of 10 nm or more and 200 nm or less. It is preferable that it is like this.

[0014] Alternatively, one aspect of the present invention is a lithium-ion battery having a positive electrode active material produced by any one of the above. It is a thium ion battery.

Advantages of the Invention

[0015] According to one aspect of the present invention, a composite oxide with a high lithium diffusion rate can be provided. Also, according to one aspect of the present invention, a lithium-containing composite phosphate with a high lithium diffusion rate can be provided. Also, according to one aspect of the present invention, a positive electrode active material with a high lithium diffusion rate can be provided. Also, according to one aspect of the present invention, a lithium-ion battery with a high output can be provided. Also, according to one aspect of the present invention, a lithium-ion battery with low cost can be provided. Also, according to one aspect of the present invention, a novel battery can be provided. It can be provided.

[0016] Note that one aspect of the present invention is not limited to these effects. For example, one aspect of the present invention may, in some cases or depending on the situation, have effects other than these. Or, for example, one aspect of the present invention may, in some cases or depending on the situation, not have these effects. Or, for example, one aspect of the present invention may, in some cases or depending on the situation, not have these effects.

Brief Description of the Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these descriptions, and those skilled in the art can easily understand that the form and details can be variously changed. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below. It is not to be construed as such.

[0019] In addition, in each of the figures described in this specification, the size, thickness, etc. of each element such as a film, layer, substrate, region, etc. may be exaggerated for the sake of clarity of individual explanations. Therefore, each component is not necessarily limited to its size, nor is it limited to the relative size between each component. It is not.

[0020] In addition, in this specification, etc., ordinal numbers such as first, second, etc. are used for convenience It does not indicate the order of processes, the order of lamination, etc. Therefore, for example, "the first one" can be appropriately replaced with "the second one", "the third one", etc. for explanation. Also, the ordinal numbers described in the specification, etc. and the ordinal numbers used to specify one aspect of the present invention may not match.

[0021] In the configuration of the present invention described in this specification, etc., the same parts or parts having the same function are commonly used with the same reference signs between different drawings, and the repeated description thereof is omitted. Also when referring to parts having the same function, the hatching pattern may be the same and no reference signs may be particularly assigned in some cases.

[0022] In this specification, etc., both the positive electrode and the negative electrode for the power storage device may be collectively referred to as the electrode. In this case, however, the electrode indicates at least one of the positive electrode and the negative electrode.

[0023] (Embodiment 1) In this embodiment, a lithium-containing composite phosphate of one aspect of the present invention will be described.

[0024] The lithium-containing composite phosphate which is one aspect of the present invention is produced using the liquid phase method, more preferably the hydrothermal method. Also, by producing the lithium-containing composite phosphate which is one aspect of the present invention at a lower temperature, a lithium-containing composite phosphate with particles of a more excellent shape may be obtained. For example, by producing at a lower temperature, a lithium-containing composite phosphate having a flat shape or a columnar shape may be obtained in some cases.

[0025] The lithium-ion battery which is one aspect of the present invention uses, as the active material of the electrode, one aspect of the present invention Preferably, it has a lithium-containing composite phosphate.

[0026] By making the lithium-containing composite phosphate into particles having a flat shape, for example, spherical particles compared with, in an electrode using the lithium-containing composite phosphate as an active material, per unit volume the filling rate of the active material may be improved. Here, the filling rate is the ratio of the volume of the active material to the total volume. Also, by making the particles have a flat shape, for example, the output of a lithium ion battery may be increased. Here, the high output of the lithium ion battery means that the current density is high in at least one of charging and discharging.

[0027] In addition, the lithium-containing composite phosphate which is one aspect of the present invention is produced at a lower temperature therefore, the productivity of the production process can be improved. Also, by producing at a lower temperature the cost may be made lower in some cases.

[0028] In addition, the lithium-containing composite phosphate which is one aspect of the present invention is preferably in the form of particles and the shape of the particles is preferably columnar, and more preferably flat.

[0029] <Production method> The production method of the lithium-containing composite phosphate which is one aspect of the present invention will be described with reference to FIG. 1. Explain.

[0030] In step S201a, a lithium compound is weighed. Also, in step S201b a phosphorus compound is weighed.

[0031] Here, the lithium-containing composite phosphate which is preferably obtained as the composition A described later Let the atomic ratio of lithium, metal M(II), and phosphorus be x:y:z. Also, in step the number of moles of lithium in the lithium compound weighed in S201a is f, and in step S201b the number of moles of phosphorus in the phosphorus compound weighed is g, and the number of moles of metal M(II) in the M(II) compound weighed in step S201c is h. f / g is 1.5 times or more and 3.5 times or less of x / y, more preferably greater than 2.6 times and less than 3.4 times, and h / g is 0. 7 times or more and 1.3 times or less. Here, when x:y:z = 1:1:1, for example, olivine-type lithium-containing composite phosphate can be obtained.

[0032] Typical examples of the lithium compound include lithium chloride (LiCl), lithium acetate (LiC H3COO), lithium oxalate ((COOLi)2), lithium carbonate (Li2CO3) , lithium hydroxide monohydrate (LiOH·H2O), etc.

[0033] Typical examples of the phosphorus compound include phosphoric acid such as orthophosphoric acid (H3PO4), diammonium hydrogen phosphate ((NH4)2HPO4), ammonium dihydrogen phosphate (NH4H2PO4 ), etc., such as ammonium hydrogen phosphate.

[0034] Next, in step S201d, a solvent is weighed. It is preferable to use water as the solvent. Also, a mixture of water and another solvent may be used as the solvent. For example, water and alcohol may be mixed. Here, the lithium compound and the phosphorus compound, or the reaction product of the lithium compound and the phosphorus compound may have different solubilities in water and in alcohol. By using alcohol, the particle size of the formed particles becomes smaller. In addition, by using alcohol with a lower boiling point than water, the following steps can be performed more efficiently. In step S211, it may be easy to increase the pressure.

[0035] Next, in step S205, a mixed liquid A is formed. The mixed liquid A may be air, an inert gas, or the like. The reaction can be carried out under an atmosphere of, for example, nitrogen as the inert gas. As an example, in an air atmosphere, the solvent weighed in step S201d and the The lithium compound weighed in step S201a and the phosphorus compound weighed in step S201b are mixed. For example, the solvent weighed in step S201d is mixed with the solvent weighed in step S201a. The lithium compound and the phosphorus compound weighed in step S201b are added to form a mixed solution A. When the mixed solution A is formed in the air, the atmosphere is more favorable than when an inert gas is used. No device for controlling the atmosphere is required, which allows for a simplified process and low cost.

[0036] In the mixed solution A, a lithium compound, a phosphorus compound, and the lithium compound and the phosphorus compound are mixed. The reaction product with the compound precipitates in the solution, but a portion of the reaction product does not precipitate but dissolves in the solvent, i.e. It is believed that the ions exist in the solvent. If the pH of the mixture A is low, the reaction The reaction product may be easily dissolved in the solvent. If the solvent is too high, the reaction product may be easily precipitated. There is.

[0037] Instead of forming the mixed solution A through step S205, Li3PO4, Li2H Weigh out compounds containing phosphorus and lithium, such as PO4, LiH2PO4, etc., and add them to the solvent and mix. A mixed liquid A may be formed.

[0038] When the mixed solution A is an aqueous solution, the pH of the mixed solution A is determined by the type and degree of dissociation of the salt contained in the mixed solution A. Therefore, the pH of the mixed solution A varies depending on the lithium compound and phosphorus compound used as raw materials. For example, when lithium chloride is used as the lithium compound and orthophosphoric acid is used as the phosphorus compound, the mixed solution A becomes a strong acid. Also, for example, when lithium hydroxide monohydrate is used as the lithium compound, the mixed solution A tends to be alkaline.

[0039] Next, in step S207, the mixed solution A and the solution Q weighed in step S205b are mixed to form a mixed solution B. Here, by adjusting the amount or concentration of the solution Q to be added, the pH of the resulting mixed solution B and the later obtained mixed solution C can be adjusted. In step S207, for example, the solution Q may be dropped while measuring the pH of the mixed solution A. As the solution Q, an alkaline solution or an acid solution is used according to the pH of the mixed solution A. Here, by using a weakly alkaline or weakly acidic solution, the pH may be easier to adjust. For example, the pH of the alkaline solution may be 8 or more and 12 or less. Also, the pH of the acid solution may be 2 or more and 6 or less. As the alkaline solution, for example, ammonia water may be used. It is preferable to determine the pH of the solution Q so that the later described mixed solution C becomes acidic or neutral. For example, when lithium chloride is used as the lithium compound and orthophosphoric acid is used as the phosphorus compound, the solution Q may be made alkaline.

[0040] Also, in step S208, an iron(II) compound, a manganese(II) compound, a cobalt(II) compound, and a nickel(II) compound (hereinafter referred to as an M(II) compound). Weigh one or more of them.

[0041] Typical examples of iron(II) compounds include iron(II) chloride tetrahydrate (FeCl2·4H2O), iron(II) sulfate heptahydrate (FeSO4·7H2O), iron(II) acetate (Fe(CH3COO)2), etc.

[0042] Typical examples of manganese(II) compounds include manganese(II) chloride tetrahydrate (MnCl2·4H 2O), manganese(II) sulfate monohydrate (MnSO4·H2O), manganese(II) acetate tetrahydrate (Mn( CH3COO)2·4H2O), etc.

[0043] Typical examples of cobalt(II) compounds include cobalt(II) chloride hexahydrate (CoCl2·6H 2O), cobalt(II) sulfate heptahydrate (CoSO4·7H2O), cobalt(II) acetate tetrahydrate (Co (CH3COO)2·4H2O), etc.

[0044] Typical examples of nickel(II) compounds include nickel(II) chloride hexahydrate (NiCl2·6H 2O), nickel(II) sulfate hexahydrate (NiSO4·6H2O), nickel(II) acetate tetrahydrate (Ni (CH3COO)2·4H2O), etc.

[0045] Next, in step S209, a mixed solution C is formed. Step S209 can be carried out in an atmosphere such as air , an inert gas, etc. For example, nitrogen can be used as the inert gas. Here, as an example, in an air atmosphere, the mixed solution A formed in step S207 and the M(II) compound weighed in step S208 are mixed to form a mixed solution C. When step S209 is carried out in an air atmosphere, step S208 should be carried out immediately before step S209, for example, within 1 hour, more preferably within 20 minutes, and even more preferably within 10 minutes. is preferable.

[0046] Also, as shown in FIG. 2, in step S209, a solvent may be added to adjust the concentration of the mixture C. In the flow shown in FIG. 2, after forming a mixture of the mixture B and the M(II) compound, the solvent is weighed in step S209b, and in step S209, the solvent is mixed with the mixture to prepare the mixture C.

[0047] Next, in step S211, after putting the mixture C into a heat-resistant and pressure-resistant container such as an autoclave, the temperature is set to 100° C. or higher and 350° C. or lower, more preferably greater than 100° C. and less than 120° C, the pressure is set to 0.1 MPa or higher and 100 MPa or lower, more preferably 0.1 MPa or higher and 2 MPa or lower, and the mixture is heated for 0.5 hours or longer and 24 hours or shorter, more preferably 1 hour or longer and 10 hours or shorter, even more preferably 1 hour or longer and less than 5 hours, and then cooled, and the solution in the heat-resistant and pressure-resistant container is filtered, washed with water, and dried. Then, the solution is separated. For example, filtration and washing are performed. After that, drying is performed in step S213 to obtain the composite A.

[0048] Here, as the composite A, a lithium-containing composite phosphate, more specifically, for example, an olivine-type lithium-containing composite phosphate (LiMPO4 (M is one or more of Fe(II), Ni(II), Co( II), Mn(II))) is preferably obtained. Depending on the type of the M(II) compound, as the lithium-containing composite phosphate, LiFePO4, LiNiPO4, LiC oPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiF e a Mn b PO4, LiNia Co b PO4, LiNi a Mn b PO4 (a + b is 1 or less , 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1 , 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1) etc. can be obtained as appropriate. Also, in this embodiment The lithium-containing composite phosphate obtained may be a single crystal grain.

[0049] By performing crystal analysis such as XRD or electron diffraction on the composite A, The crystal structure can be specified. By performing crystal analysis of the composite A, a crystal structure belonging to the space group Pnm a may be obtained. Here, LiM having an olivine-type crystal structure PO4 belongs to, for example, the space group Pnma.

[0050] In step S211, by lowering the reaction temperature, the temperature of the apparatus can be lowered . Also, the cost required for the reaction can be reduced. Therefore, productivity can be improved . Also, by lowering the reaction temperature, a flatter shape may be obtained as the particles of the composite A.

[0051] In FIG. 6 of Patent Document 1, a potential-pH diagram in the case of iron is shown. In Patent Document 1 As can be seen from FIG. 6, when the pH is high, iron hydroxide or iron oxide is stable and when the pH is low, iron(II) ions are stable.

[0052] By lowering the reaction temperature in step S211, the rate of the formation reaction of composition A may be reduced and by-products may be more likely to be formed. The formation of by-products leads to a decrease in the yield. Here, the by-products refer to, for example, compounds different from the target compound, composition A. The formation rate of composition A is preferably faster than the formation rate of by-products.

[0053] By making the mixed solution C acidic (that is, by lowering the pH), even when the reaction temperature in step S 211 is lowered, the formation of by-products can be suppressed, which is preferable. Yes.

[0054] When the pH of the mixed solution C is high, it has a large amount of hydroxide ions. When the pH of the mixed solution C is high, metal M hydroxide may be formed. From this metal M hydroxide, metal M oxide may be obtained. For example, iron ions react with hydroxide ions to form Fe (OH)2, FeOOH is formed from Fe(OH)2, and Fe2O3 may be obtained from FeOOH. That is, in the mixed solution C, in addition to the reaction of M ions, P ions, and lithium ions to obtain the preferred lithium-containing composite phosphate as composition A, side reactions such as the formation of M ion hydroxide may occur.

[0055] That is, in the mixed solution C, in addition to the reaction of M ions, P ions, and lithium ions to obtain the preferred lithium-containing composite phosphate as composition A, side reactions such as the formation of M ion hydroxide may occur. By lowering the pH of the mixed solution C, the side reaction may be suppressed in some cases. On the other hand, the mixture ion hydroxide may occur.

[0056] By lowering the pH of the mixed solution C, the side reaction may be suppressed in some cases. On the other hand, the mixture If the pH of liquid C is too low, the target compound A may dissolve. Alternatively, compound A may not be produced.

[0057] By lowering the pH of the mixed liquid C, the dissolution and generation of particles are repeated. For example, it is considered that particles with poor crystallinity dissolve again and particles with excellent crystallinity grow. As particles with excellent crystallinity, for example, flat-shaped or columnar particles may be easily obtained.

[0058] As a by-product, for example, a phosphate compound having iron with different valences (including its hydrate) may be obtained. Alternatively, as a by-product, for example, ammonium iron phosphate (including its hydrate) may be obtained.

[0059] The pH of the mixed liquid C is, for example, 1.0 or more and 8.0 or less, more preferably 2.0 or more and 7.0 or less, even more preferably 3.0 or more and 6.0 or less, and even more preferably 3.5 or more and 5.0 or less.

[0060] Here, when iron is used as the element M, the pH of the mixed liquid C is 3.0 or more and 6.0 or less, more preferably 3.5 or more and 5.0 or less, and even more preferably 3.5 or more and 4.0 or less, and the reaction temperature in step S211 is, for example, greater than 100 °C and 119 °C or less, more preferably 1 03 °C or more and 117 °C or less, and even more preferably 105 °C or more and 115 °C or less.

[0061] In addition, it is preferable to separate and remove the generated by-products, for example, by filtration. For example, prepare a solution in which the by-product is easily dissolved, mix it with the substance obtained after step S211, and then filter it. For example, an acid solution can be mentioned as the solution.

[0062] <Particle shape> The lithium-containing composite phosphate according to one embodiment of the present invention is preferably in the form of particles, and the particles preferably have a flat shape.

[0063] Here, the flat-shaped particles have the widest surface and the thickness in a direction substantially perpendicular to the surface. For example, the thickness 667 of the flat-shaped particles is 5 nm or more and 500 nm or less, more preferably 10 nm or more and 200 nm or less. The length 666 of the widest surface of the flat-shaped particles is 50 nm or more and 3 μm or less. Alternatively, the length 666 is 3 times or more and 200 times or less, more preferably 10 times or more and 50 times or less the thickness 667. Here, the length of the surface may be, for example, the diameter of the circle obtained by converting the surface area of the surface into a circle. FIG. 3 shows an example of flat-shaped particles and an example of the length 6 66 and the thickness 667. FIG. 3(A) shows an example in which the particles have a substantially flat polygonal column shape . FIG. 3(B) shows an example in which the side surface of the widest surface of the particles has a curve .

[0064] Here, for example, when the lithium-containing composite phosphate has an olivine structure, the direction of the thickness 667 is preferably substantially parallel to the direction of the b-axis, and the angle formed by the direction of the thickness 667 and the direction of the b-axis is preferably 0° or more and 20° or less. When the thickness 667 and the b-axis are substantially parallel , lithium diffuses easily in the lithium-containing composite phosphate, and the output characteristics of the storage battery are improved.

[0065] Alternatively, the lithium-containing composite phosphate according to one embodiment of the present invention may have a columnar shape. When the length of the cross section is larger than the height, it has the aforementioned flat shape. Also, the length of the cross section ​When it is smaller than the height, for example, the b-axis is preferably substantially perpendicular to the height direction of the pillar. Preferably, the length of the cross-section is 5 nm or more and 100 nm or less, and the height is 50 nm or more and 3 μm or less.

[0066] <xrd> Figure 29(A) shows the lithium-containing composite phosphate of one embodiment of the present invention, which will be described in the examples below. This is the measurement result by the θ-2θ method of XRD. As shown as A to F in the figure, in the range where 2θ is from 17° to 36°, when 2θ is in the range of 17° to 36°, six peaks with maximum values at 2θ of 17.1°, 20.7°, 25.5°, 2 9.8°, 32.1°, and 35.6° are observed. These six peaks correspond to PDF (Powder Diffraction File)-numbers 01-070-6684 of ICDD (International Centre for Diffraction Data). Therefore, it is suggested that the lithium-containing composite phosphate corresponds to LiFePO4 of the space group Pnma.

[0067] The lithium-containing composite phosphate of one embodiment of the present invention preferably has peak A, peak B, peak C, peak D, peak E, and peak F in the measurement by the θ-2θ method of XRD. When the lithium-containing composite phosphate is oriented, one or more of the six peaks of peak A to peak F may be difficult to observe. Therefore, the lithium-containing composite phosphate of one embodiment of the present invention preferably has two or more of the six peaks of peak A to peak F, more preferably has three or more peaks, and even more preferably has all six peaks. Let the 2θ at which peak A takes the maximum value be A1 [°], and the half-width of the peak be A2 [°]. Let the 2θ at which peak B takes the maximum value be B1 [°], and the half-width of the peak be B2 [°]. Let the peak C be

[0068] Let 2θ that takes the maximum value be C1 [°], and the half-value width of the peak be C2 [°]. Peak D takes the maximum value Let 2θ be D1 [°], and the half-value width of the peak be D2 [°]. Peak E takes the maximum value Let 2θ be E1 [°], and the half-value width of the peak be E2 [°]. Peak F takes the maximum value of 2θ Let it be F1 [°], and the half-value width of the peak be F2 [°].

[0069] A1 is preferably greater than 16.82° and less than 17.52°, more preferably greater than 16.87° and less than 17.47°, still more preferably greater than 17.02° and less than 17.32°.

[0070] B1 is preferably greater than 20.45° and less than 21.15°, more preferably greater than 20.50° and less than 21.10°, still more preferably greater than 20.65° and less than 20.95°.

[0071] C1 is preferably greater than 25.24° and less than 25.94°, more preferably greater than 25.29° and less than 25.89°, still more preferably greater than 25.44° and less than 25.74°.

[0072] D1 is preferably greater than 29.40° and less than 30.10°, more preferably greater than 29.45° and less than 30.05°, still more preferably greater than 29.60° and less than 29.90°.

[0073] E1 is preferably greater than 31.90° and less than 32.60°, more preferably greater than 31.95° and less than 32.55°, still more preferably greater than 32.1° and less than 32.4°.

[0074] F1 is preferably greater than 35.28° and less than 35.985°, more preferably greater than 35.33° and less than 35.93°, still more preferably greater than 35.48° and less than 35.78°.

[0075] The full width at half maximum of the peaks observed in XRD may become narrower when the crystallinity is high . Also, it becomes narrower when the crystal grain size is large. Therefore, the full width at half maximum of the peaks observed in XRD is preferably less than 2, more preferably less than 1, still more preferably less than 0.3, and even more preferably less than 0.2. A2, B2, C2, D2, E2 and F2 are, for example, greater than 0.02 and less than 2, or greater than 0.03 and less than 2, or greater than 0.03 and less than 1.

[0076] <Effect of pH> Although details will be described in the examples described later, Fig. 29(A) shows the XRD measurement results of the product obtained after step S211 when the pH of the mixed solution B is near 6 and the pH of the mixed solution C is near 5. Shown.

[0077] Fig. 28(B) shows the XRD measurement results of the product obtained after step S 211 when the pH of the mixed solution B is near 10 and the pH of the mixed solution C is near 9. Details will be described in the later examples It is suggested that it corresponds to the peak of Li3PO4. In step S207, it is conceivable that Li3PO4 used when preparing the mixed solution remains. Also, the peak observed at 31.7 ° may correspond to NH4FePO4·H2O.

[0078] Fig. 28(A) shows step S when the pH of the mixed solution B is near 8 and the pH of the mixed solution C is near 6 The XRD measurement results of the product obtained after 211 are shown. Details will be described in the examples below, It is suggested that it corresponds to the peak of NH4FePO4·H2O from the database.

[0079] When the pH of the mixed solution B becomes high in this way, for example, when it exceeds 7, the yield of the target compound A decreases, and compounds such as Li3PO4 and NH4FePO4·H2O may be generated.

[0080] The lithium-containing composite phosphate of one aspect of the present invention can be used as an active material of a lithium-ion battery. The lithium-containing composite phosphate of one aspect of the present invention preferably has an olivine-type structure. Further, when the lithium-containing composite phosphate of one aspect of the present invention has an olivine-type structure, the capacity per unit weight of the active material is, for example, at a rate of 0.2C, 100 mAh / g or more and 170 mAh / g or less, or 130 mAh / g or more and 160 mAh / g or less.

[0081] (Embodiment 2) In this embodiment, a storage battery of one aspect of the present invention will be described.

[0082] A storage battery of one aspect of the present invention has a positive electrode, a negative electrode, and an electrolyte.

[0083] The positive electrode active material preferably has, for example, the lithium-containing composite phosphate described in Embodiment 1 or the like.

[0084] [Negative electrode active material] When a negative electrode active material is used as the active material, for example, an alloy-based material, a carbon-based material, or the like can be used.

[0085] ​​​As the negative electrode active material, it is possible to use an element that can perform a charge-discharge reaction through an alloying / dealloying reaction with lithium. 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 compared to carbon, and in particular, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Also, compounds containing these elements may be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag 3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. are available. Here, elements that can perform a charge-discharge reaction through an alloying / dealloying reaction with lithium, and compounds containing such elements, etc. are sometimes referred to as alloy-based materials. In this specification, etc., SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be represented as Si Ox. Here, x preferably has a value near 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0086]

[0087] As the carbon-based material, graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black, etc. can be used. For graphite, artificial graphite, natural graphite, etc. can be mentioned. As artificial graphite, for example, meso

[0088] ​​​​​​​​Examples include carbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. Among these, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape, which is preferable. Also, MCMB can relatively easily reduce its surface area, which may be preferable. Examples of natural graphite include flake graphite, spheroidized natural graphite, etc.

[0089] Graphite exhibits a potential as low as that of metallic lithium (0.05 V or more and 0.3 V or less vs. Li / Li ) when lithium ions are inserted into the graphite (when forming a lithium-graphite + intercalation compound). As a result, a lithium-ion secondary battery can exhibit a high operating voltage. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and high

[0090] safety compared to metallic lithium, and thus is preferable. Ti5O 12 )), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5 ), tungsten oxide (WO2), molybdenum oxide (MoO2), and other oxides can be used as the negative electrode active material.

[0091] Also, as the negative electrode active material, Li3N-type structures, which are complex nitrides of lithium and transition metals, Li 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2. 6Co 0.4 N3 has a large charge-discharge capacity (900 mAh / g, 1890 mAh / cm 3 ). It is preferable to show.

[0092] When using a complex nitride of lithium and a transition metal, since the negative electrode active material contains lithium ions it is preferable to combine it with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material. When using a material containing lithium ions as the positive electrode active material it is also possible to use a complex nitride of lithium and a transition metal as the negative electrode active material by previously desorbing the lithium ions contained in the positive electrode active material.

[0093] In addition, a material in which a conversion reaction occurs can also be used as the negative electrode active material. For example, transition metal oxides such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO) that do not form an alloy with lithium may be used as the negative electrode active material. Materials in which a conversion reaction occurs further include oxides such as Fe2O3, CuO, Cu2O, RuO2, and Cr2O3 0.89

[0094] [Pre-doping] In addition, when a film is formed during the first charge and discharge, an irreversible reaction occurs. For example, when the irreversible reaction in either the positive electrode or the negative electrode is larger, the charge-discharge balance is disrupted and the capacity of the storage battery may decrease. In some cases, the decrease in capacity can be suppressed by performing electrode recombination after charging and discharging using a counter electrode. For example, charging by combining the positive electrode with the negative electrode By removing and fabricating a storage battery in combination with a new positive electrode, it may be possible to suppress a decrease in the capacity of the storage battery. This method may be referred to as pre-doping or pre-aging. This method may be called pre-doping or pre-aging.

[0095] As the current collectors of the positive electrode and the negative electrode, materials with high conductivity such as metals such as stainless steel, gold, platinum, aluminum, titanium, and alloys thereof can be used. When the current collector is used for the positive electrode, it is preferably insoluble at the potential of the positive electrode. When the current collector is used for the negative electrode, it is preferably not alloyed with carrier ions such as lithium. Also, an aluminum alloy added with an element for improving heat resistance such as silicon, titanium, neodymium, scandium, molybdenum, etc. can be used. Also, it may be formed of a metal element that reacts with silicon to form a silicide. Metal elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The current collector can be appropriately used in shapes such as foil, plate (sheet), net, punched metal, expanded metal, etc. The current collector preferably has a thickness of 5 μm or more and 30 μm or less. The current collector can be appropriately used in shapes such as foil, plate (sheet), net, punched metal, expanded metal, etc. The current collector preferably has a thickness of 5 μm or more and 30 μm or less. The metal elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The current collector can be appropriately used in shapes such as foil, plate (sheet), net, punched metal, expanded metal, etc. The current collector preferably has a thickness of 5 μm or more and 30 μm or less. The current collector preferably has a thickness of 5 μm or more and 30 μm or less.

[0096] In addition, the positive electrode and the negative electrode may have a conductive aid. As the conductive aid, for example, a carbon material, a metal material, or a conductive ceramic material, etc. can be used. Also, as the conductive aid, a fibrous material may be used. The content of the conductive aid with respect to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. The content of the conductive aid with respect to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less.

[0097] A conductive additive can form an electrical conduction network in the electrode. The conductive additive can maintain the electrical conduction path between the positive electrode active materials. By adding a conductive additive to the active material layer, an active material layer having high electrical conductivity can be realized.

[0098] As the conductive additive, for example, natural graphite, artificial graphite such as mesocarbon microbeads, carbon fibers, etc. can be used. As the carbon fiber, for example, carbon fibers such as mesophase pitch-based carbon fibers, isotropic pitch-based carbon fibers, etc. can be used. Also, as the carbon fiber, carbon nanofibers, carbon nanotubes, etc. can be used. Carbon nanotubes can be produced, for example, by a vapor growth method. Further, as the conductive additive, for example, carbon materials such as carbon black (such as acetylene black (AB)), graphite (black lead) particles, graphene, fullerenes, etc. can be used. Also, for example, metal powders such as copper, nickel, aluminum, silver, gold, etc., metal fibers, conductive ceramic materials, etc. can be used.

[0099] Also, a graphene compound may be used as the conductive additive.

[0100] The graphene compound may have excellent electrical properties such as high electrical conductivity, and excellent physical properties such as high flexibility and high mechanical strength. Also, the graphene compound has a planar shape. The graphene compound enables surface contact with low contact resistance. Also, it may have very high electrical conductivity even when thin, and can efficiently form a conductive path in the active material layer with a small amount. Therefore, using the graphene compound as the conductive additive This is preferable because it can increase the contact area between the active material and the conductive aid. Also it is preferable because it may be able to reduce the electrical resistance. Here, as the graphene compound for example, it is particularly preferable to use graphene or multi-graphene or reduced Graphene Oxide (hereinafter, RGO). Here, RGO refers to a compound obtained by reducing, for example, graphene oxide (GO). 。

[0101] When using an active material with a small particle size, for example, an active material of 1 μm or less, the specific surface area of the active material is large, and more conductive paths connecting the active materials are required. In such a case, it is particularly preferable to use a graphene compound that can efficiently form conductive paths even in a small amount. 。

[0102] Hereinafter, as an example, a cross-sectional configuration example in the case of using a graphene compound as a conductive aid in the active material layer will be described. 。

[0103] Figure 4(A) shows a longitudinal sectional view of the active material layer. The active material layer includes granular active material 103, a graphene compound 321 as a conductive aid, and a binder (not shown). Here, as the graphene compound 321, for example, graphene or multi-graphene may be used. 。 Here, it is preferable that the graphene compound 321 has a sheet-like shape. Also, the graphene compound 321 may be a plurality of multi-graphenes, and / or a plurality of graphenes may be partially overlapped to form a sheet-like shape. 。 。 。

[0104] In the longitudinal section of the active material layer, as shown in Figure 4(A), schematically inside the active material layer The sheet-like graphene compound 321 is uniformly dispersed. In Fig. 4(A), the graphene compound 321 is schematically represented by a thick line, but actually it is a thin film having a thickness of a single layer or multiple layers of carbon molecules. A plurality of graphene compounds 321 are formed so as to wrap, cover, or adhere onto the surfaces of a plurality of granular active materials 103, and thus are in surface contact with each other.

[0105] Here, by bonding a plurality of graphene compounds to each other, a network-like graphene compound sheet (hereinafter referred to as a graphene compound net or a graphene net) can be formed. When the active material is covered with the graphene net, the graphene net can also function as a binder for bonding the active materials to each other. Therefore, the amount of the binder can be reduced or the binder can be not used, and thus the ratio of the active material in the electrode volume and the electrode weight can be improved. That is, the capacity of the power storage device can be increased.

[0106] Here, it is preferable to use graphene oxide as the graphene compound 321, mix it with the active material to form a layer serving as an active material layer, and then reduce it. By using graphene oxide having extremely high dispersibility in a polar solvent for the formation of the graphene compound 321, the graphene compound 321 can be dispersed substantially uniformly inside the active material layer. Since the solvent is volatilized and removed from the dispersion medium containing uniformly dispersed graphene oxide to reduce the graphene oxide, the graphene compounds 321 remaining in the active material layer partially overlap with each other and are dispersed to such an extent that they are in surface contact with each other, so that a three-dimensional conductive path can be formed. Note that graphene oxide Reduction of the yen may be performed, for example, by heat treatment or using a reducing agent.

[0107] Therefore, unlike granular conductive aids such as acetylene black that make point contact with the active material, graphene compound 321 enables surface contact with low contact resistance, so it can improve the electrical conductivity between granular active material 103 and graphene compound 321 with a smaller amount than ordinary conductive aids and can increase the ratio of the active material layer of the active material 103. Thus, the discharge capacity of the power storage device can be increased.

[0108] Also, the positive electrode and the negative electrode may have a binder. As the binder, for example, styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene-diene copolymer and other rubber materials are preferably used. Also, fluororubber can be used as the binder.

[0109] Also, as the binder, it is preferable to use, for example, a water-soluble polymer. As the water-soluble polymer, for example, polysaccharides can be used. As the polysaccharide, carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, cellulose derivatives such as regenerated cellulose, and starch can be used. Also, it is more preferable to use these water-soluble polymers in combination with the aforementioned rubber materials.

[0110] Alternatively, as the binder, polystyrene, polymethyl acrylate, polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), poly Ethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, poly ethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylo nitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, nitrocell lose and other materials are preferably used.

[0111] The binder may be used in combination of a plurality of the above.

[0112] For example, a material with particularly excellent viscosity adjustment effect may be used in combination with other materials. For example, rubber materials and the like are excellent in adhesive force and elastic force, but it may be difficult to adjust the viscosity when mixed with a solvent. In such a case, for example, it is preferable to mix with a material having a particularly excellent viscosity adjustment effect. As the material having a particularly excellent viscosity adjustment effect, for example, a water-soluble polymer may be used. In addition, as the water-soluble polymer having a particularly excellent viscosity adjustment effect, the above-mentioned polysaccharides, for example, car boxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxy propyl cellulose and diacetyl cellulose, cellulose derivatives such as regenerated cellulose, and starch can be used. In addition, cellulose derivatives such as carboxymethyl cellulose can be made into salts such as sodium salts and ammonium salts of carboxymethyl

[0113] cellulose, so that the solubility is increased, and it becomes easier to exhibit the effect as a viscosity modifier. By increasing the solubility, the dispersibility with the active material and other components can also be improved when preparing the slurry of the electrode. In this specification, As for cellulose and cellulose derivatives used as a binder for an electrode, those including their salts shall also be included.

[0114] The water-soluble polymer stabilizes the viscosity by dissolving in water, and also stably disperses an active material and other materials combined as a binder, such as styrene-butadiene rubber, etc. in an aqueous solution. Moreover, it is expected to be easily adsorbed stably on the surface of the active material because it has a functional group. In addition, cellulose derivatives such as carboxymethyl cellulose, for example, have many materials having functional groups such as hydroxyl groups and carboxyl groups, and it is expected that the polymers interact with each other and exist widely covering the surface of the active material. When a binder covering the surface of the active material or in contact with the surface forms a film, it is also expected to function as a passive film and suppress the decomposition of the electrolyte. Here, the passive film is a film having no electron conductivity or a film having extremely low electric conductivity. For example, when a passive film is formed on the surface of the active material, the decomposition of the electrolyte can be suppressed at the battery reaction potential.

[0115] Moreover, it is more desirable that the passive film suppresses the electric conductivity while allowing lithium ions to conduct. When a binder covering the surface of the active material or in contact with the surface forms a film, it is also expected to function as a passive film and suppress the decomposition of the electrolyte. Here, the passive film is a film having no electron conductivity or a film having extremely low electric conductivity. For example, when a passive film is formed on the surface of the active material, the decomposition of the electrolyte can be suppressed at the battery reaction potential. Moreover, it is more desirable that the passive film suppresses the electric conductivity while allowing lithium ions to conduct.

[0116] [Method for manufacturing an electrode] As an example of a method for manufacturing a negative electrode and a positive electrode, an electrode can be manufactured by preparing a slurry and coating the slurry. An example of a method for preparing the slurry used for electrode manufacturing will be described.

[0117] Here, the solvent used for preparing the slurry is preferably a polar solvent. For example, water ​​, any one or a mixture of two or more of methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO( ) can be used. ( (

[0118] ( First, the active material, the conductive assistant, and the binder are mixed to prepare mixture A (step S1( 10). Next, a solvent is added to mixture A, and kneading (kneading at high viscosity) is performed to prepare mixture ( B (step S120). Here, mixture B is preferably in a paste form, for example. Here, when adding the second binder in subsequent step S141, ( it may not be necessary to add the first binder in step S110. ( ( (

[0119] ( ( Next, a solvent is added to mixture B, and kneading is performed to prepare mixture C (step S130( ). ( (

[0120] ( Next, when using the second binder, the second binder is added to prepare mixture D (( step S141). At this time, a solvent may be added. Also, when not using the second binder ( , a solvent is added as necessary to prepare mixture E (step S142). ( (

[0121] ( Next, for example, mixture D or mixture E prepared in a reduced-pressure atmosphere is kneaded to prepare mixture F ( (step S150). At this time, a solvent may be added. Here, in the mixing and kneading steps from step S110 to ( step S150, for example, a kneader can be used ( . ( (

[0122] ( Next, the viscosity of mixture F is measured (step S160). Then, a solvent is added as necessary ( Add and adjust the viscosity. Through the above steps, a slurry for coating the active material layer is obtained. Obtained.

[0123] Here, for example, in steps S130 to S160, the higher the viscosity of mixture C to mixture F, the better the dispersibility (mix well with each other) of the active material, binder, and conductive assistant in the mixture may be. Therefore, for example, it is preferable that the viscosity of mixture F is higher. On the other hand, if the viscosity of mixture F is too high, for example, the coating speed of the electrode may decrease, which may not be preferable from the perspective of productivity.

[0124] Next, a method for forming an active material layer on a current collector using the prepared slurry will be described. Obtained.

[0125] First, apply the slurry on the current collector. Here, before applying the slurry, surface treatment may be performed on the current collector. Examples of the surface treatment include corona discharge treatment, plasma treatment, undercoat treatment, etc. Here, the undercoat refers to a film formed on the current collector for the purpose of reducing the interfacial resistance between the active material layer and the current collector or increasing the adhesion between the active material layer and the current collector. Note that the undercoat does not necessarily have to be in the form of a film and may be formed in an island shape. Also, the undercoat may react with the active material to exhibit capacitance. As the undercoat, for example, a carbon material can be used. As the carbon material, for example, graphite, carbon black such as acetylene black and ketjen black (registered trademark), carbon nanotubes, etc. can be used. (registered trademark), etc. can be used.

[0126] For the application of the slurry, a slot die method, gravure, blade method, or a combination thereof can be used. Also, a continuous coater or the like may be used for the application. Next, the active material layer can be formed by volatilizing the solvent of the slurry.

[0127] Next, the active material layer can be formed by volatilizing the solvent of the slurry.

[0128] The step of volatilizing the solvent of the slurry is preferably carried out in a temperature range of 50°C or higher and 200°C or lower, more preferably 60°C or higher and 150°C or lower. For example, heat treatment can be carried out on a hot plate in an air atmosphere under conditions of 30°C or higher and 70°C or lower for 10 minutes or more, and then, for example, heat treatment can be carried out in a reduced-pressure environment under conditions of room temperature or higher and 100°C or lower for 1 hour or more and 10 hours or less.

[0129] Alternatively, heat treatment may be carried out using a drying oven or the like. When using a drying oven, for example, heat treatment can be carried out at a temperature of 30°C or higher and 120°C or lower for 30 seconds or more and 20 minutes or less.

[0130]

[0131]

[0132] Or the temperature may be increased step by step. For example, after heat treatment at 60°C or lower for 10 minutes or less, heat treatment may be further carried out at a temperature of 65°C or higher for 1 minute or more.

[0132] The thickness of the active material layer formed in this way is, for example, preferably 5 μm or more and 300 μm or less, more preferably 10 μm or more and 150 μm or less. Also, the active material loading of the active material layer is, for example, preferably 2 mg / cm² or more and 50 mg / cm² or less.

[0133] 2 2 The active material layer may be formed on both sides of the current collector or only on one side. ​​​​Or, it may have a region where the active material layer is partially formed on both sides.

[0134] After the solvent is volatilized from the active material layer, compression may be performed by a compression method such as a roll press method or a flat press method. Pressing may be performed. Heat may be applied during pressing.

[0135] Note that pre-doping may be performed on the active material layer. The method of performing pre-doping on the active material layer is not particularly limited, but for example, it can be performed electrochemically. For example, before battery assembly using lithium metal as the counter electrode, lithium can be pre-doped into the active material layer in the electrolyte solution described later. Alternatively, for the negative electrode, a counter electrode for pre-doping may be prepared as the positive electrode for pre-doping, and then the counter electrode for pre-doping may be removed. By performing pre-doping it is possible to particularly suppress a decrease in the charge-discharge efficiency of the first cycle and increase the capacity of the storage battery.

[0136] This embodiment can be implemented in appropriate combination with other embodiments.

[0137] (Embodiment 3) In this embodiment, a power storage device according to one aspect of the present invention will be described.

[0138] As an example of a power storage device according to one aspect of the present invention, secondary batteries using electrochemical reactions such as lithium ion batteries, electrochemical capacitors such as electric double layer capacitors and redox capacitors, air batteries, fuel cells, etc. are exemplified.

[0139] <Thin-Film Storage Battery> FIG. 5 shows a thin-film storage battery as an example of a power storage device. If the thin-film storage battery has a flexible configuration, it can be mounted on an electronic device having at least a part of a flexible portion.​​ Furthermore, the rechargeable battery can also be bent in accordance with the deformation of the electronic device.

[0140] FIG. 5 shows an external view of a rechargeable battery 500 which is a thin rechargeable battery. FIGS. 6(A) and 6 (B) show a cross section A1-A2 and a cross section B1-B2 indicated by a one-dot chain line in FIG. 5. The rechargeable battery 5 00 includes a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, a negative electrode current collector 504 and a negative electrode 506 having a negative electrode active material layer 505, a separator 507, an electrolytic solution 5 08, and an exterior body 509. A separator 507 is disposed between the positive electrode 503 and the negative electrode 50 6 provided in the exterior body 509. Further, the interior of the exterior body 509 is filled with the electrolytic solution 508 .

[0141] As the solvent of the electrolytic solution 508, an aprotic organic solvent is preferable. For example, ethylene car bonate (EC), propylene carbonate (PC), butylene carbonate, chloro ethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone , dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether , methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc., one kind, or two or more of these can be used in any combination and ratio .

[0142] In addition, by using a polymer material that is gelled as the solvent of the electrolytic solution, with respect to liquid leakage properties, etc. Safety is enhanced. In addition, the secondary battery can be made thinner and lighter. Representative examples of the gelled polymer materials include silicone gel, acrylic gel, acrylonitrile gel, poly ethylene oxide-based gel, polypropylene oxide-based gel, gel of fluorine-based polymer, etc. There are also

[0143] Also, by using one or more ionic liquids (room temperature molten salts), which are flame-retardant and hardly volatile, as the solvent of the electrolytic solution, even if the internal temperature rises due to internal short circuit, overcharging, etc. of the power storage device, rupture, ignition, etc. of the power storage device can be prevented. An ionic liquid consists of a cation and an anion, and contains an organic cation and an anion. Examples of the organic cation used in the electrolytic solution include aliphatic onium cations such as quaternary ammonium cation, tertiary sulfonium cation, and quaternary phosphonium cation, and aromatic cations such as imidazolium cation and pyridinium cation. Examples of the anion used in the electrolytic solution include monovalent amide-based anion, monovalent methide-based anion, fluorosulfonic acid anion, perfluoroalkyl sulfonic acid anion, tetrafluoroborate anion, perfluoroalkyl borate anion, hexafluorophosphate anion, or perfluoroalkyl phosphate anion, etc. There are also

[0144] Also, as the electrolyte dissolved in the above solvent, in the case of using lithium ions as carriers, for example, LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, L iSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 Cl 12 Cl 12 Cl 12 , LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C 2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO 2), LiN(C2F5SO2)2 and other lithium salts can be used singly or in combinations of two or more of these in any combination and ratio.

[0145] The electrolyte used in the power storage device is preferably a highly purified electrolyte with a low content of particulate dust and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as " impurities"). Specifically, the weight ratio of impurities to the electrolyte is preferably 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0146] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butyl benzene (TBB), fluoroethylene carbonate (FEC), and LiBOB may be added to the electrolyte. The concentration of the additive may be, for example, 0.1 weight% or more and 5 weight% or less based on the total solvent.

[0147] A polymer gel electrolyte obtained by swelling a polymer with an electrolyte may also be used.

[0148] Examples of the polymer include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, etc., and copolymers containing them can be used. For example, PVDF-HFP, which is a copolymer of PVDF and hexafluoropropylene ( HFP), can be used. In addition, the formed polymer may have a porous shape.

[0149] ​​Alternatively, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as a sulfide-based or oxide-based material, or a solid electrolyte having a polymer material such as a PEO (polyethylene oxide)-based material can be used. When using a solid electrolyte, it is not necessary to install a separator or a spacer. Also, since the entire battery can be solidified, there is no risk of liquid leakage and the safety is dramatically improved.

[0150] As the separator 507, for example, paper, non-woven fabric, glass fiber, ceramics, or nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, a crylic, polyolefin, a synthetic fiber using polyurethane, etc. can be used.

[0151] The separator 507 is preferably processed into a bag shape and arranged to wrap either the positive electrode 503 or the negative electrode 506. For example, as shown in FIG. 7(A), the separator 507 is folded in half so as to sandwich the positive electrode 503, and sealed by a sealing portion 51 4 outside the region overlapping the positive electrode 503, so that the positive electrode 503 can be reliably supported within the separator 507. Then, as shown in FIG. 7(B), the positive electrode 503 and the negative electrode 5 06 wrapped by the separator 507 are alternately laminated, and the power storage battery 500 is formed by arranging them within the exterior body 509.

[0152] Next, the aging after manufacturing the power storage battery will be described. After manufacturing the power storage battery, it is preferable to perform aging. An example of the aging conditions will be described below. First, charging is performed at a rate of 0.001C or more and 0.2C or less. The temperature may be, for example, room temperature or higher and 50 °C or lower. Here, the reaction potential of the positive electrode or the negative electrode exceeds the range of the potential window of the electrolytic solution 508.​​​ In the case where electrolysis of the electrolyte occurs due to charge and discharge of the storage battery, gas may be generated due to the electrolysis of the electrolyte. When gas is generated due to the electrolysis of the electrolyte, if the gas accumulates in the cell, a region where the electrolyte cannot come into contact with the electrode surface will be generated. That is, the effective reaction area of the electrode decreases, which corresponds to an increase in the effective resistance. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. In the case where electrolysis of the electrolyte occurs due to charge and discharge of the storage battery, gas may be generated due to the electrolysis of the electrolyte. When gas is generated due to the electrolysis of the electrolyte, if the gas accumulates in the cell, a region where the electrolyte cannot come into contact with the electrode surface will be generated. That is, the effective reaction area of the electrode decreases, which corresponds to an increase in the effective resistance. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage.

[0153] Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage. Moreover, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium intercalation into graphite and at the same time, lithium precipitation on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated, if a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, and the amount of lithium that does not contribute to the capacity increases. Also, when the precipitated lithium physically falls off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage.

[0154] Moreover, after venting the gas, it may be held in a charged state at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less. When charging for the first time, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas. Moreover, after venting the gas, it may be held in a charged state at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less. When charging for the first time, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas. Moreover, after venting the gas, it may be held in a charged state at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less. When charging for the first time, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas. Moreover, after venting the gas, it may be held in a charged state at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less. When charging for the first time, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas. Moreover, after venting the gas, it may be held in a charged state at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less. When charging for the first time, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas.

[0155] FIG. 8 shows an example of welding a current collector to a lead electrode. As shown in FIG. 8(A), the positive electrode 503 wrapped by the separator 507 and the negative electrode 506 are alternately stacked. Next, the positive electrode current collector The positive electrode current collector 501 is welded to the positive electrode lead electrode 510, and the negative electrode current collector 504 is welded to the negative electrode lead electrode 511, respectively. An example of welding the positive electrode current collector 501 to the positive electrode lead electrode 510 is shown in FIG. 8(B). The positive electrode current collector 501 is welded to the positive electrode lead electrode 510 in the welding region 512 using, for example, ultrasonic welding. Also, the positive electrode current collector 501 has the curved portion 513 shown in FIG. 8(B), which can relieve the stress generated when an external force is applied after the production of the storage battery 500, and can improve the reliability of the storage battery 500.

[0156] In the storage battery 500 shown in FIGS. 5 and 6, the positive electrode lead electrode 510 is ultrasonically joined to the positive electrode current collector 501 of the positive electrode 503, and the negative electrode lead electrode 511 is ultrasonically joined to the negative electrode current collector 504 of the negative electrode 506, respectively. Also, the positive electrode current collector 501 and the negative electrode current collector 504 can also serve as terminals for obtaining electrical contact with the outside. In that case, without using lead electrodes, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be arranged to be exposed outside from the exterior body 509. In FIG. 5, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side. However, as shown in FIG. 9, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 may be arranged on different sides. In this way, since the lead electrodes of the storage battery according to one aspect of the present invention can be freely arranged, the degree of design freedom is high. Therefore, the degree of design freedom of a product using the storage battery according to one aspect of the present invention can be increased.

[0157] Also, the productivity of a product using the storage battery according to one aspect of the present invention can be increased. In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly

[0158] In the storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, or poly On a film made of materials such as carbonate, ionomer, and polyamide, a metal thin film with excellent flexibility such as aluminum, stainless steel, copper, or nickel is provided. Further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided on the metal thin film as the outer surface of the exterior body. A three-layer structured film can be used. On a film made of materials such as carbonate, ionomer, and polyamide, a metal thin film with excellent flexibility such as aluminum, stainless steel, copper, or nickel is provided. Further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided on the metal thin film as the outer surface of the exterior body. A three-layer structured film can be used. On a film made of materials such as carbonate, ionomer, and polyamide, a metal thin film with excellent flexibility such as aluminum, stainless steel, copper, or nickel is provided. Further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided on the metal thin film as the outer surface of the exterior body. A three-layer structured film can be used. On a film made of materials such as carbonate, ionomer, and polyamide, a metal thin film with excellent flexibility such as aluminum, stainless steel, copper, or nickel is provided. Further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided on the metal thin film as the outer surface of the exterior body. A three-layer structured film can be used.

[0159] Also, in FIG. 6, as an example, the number of pairs of the opposing positive electrode active material layer and negative electrode active material layer is five pairs. Of course, the number of pairs of the active material layers is not limited to five pairs, and may be more or less. Also, in FIG. 6, as an example, the number of pairs of the opposing positive electrode active material layer and negative electrode active material layer is five pairs. Of course, the number of pairs of the active material layers is not limited to five pairs, and may be more or less. When the number of active material layers is large, a battery with a larger capacity can be obtained. Also, when the number of active material layers is small, the battery can be thinned and made to have excellent flexibility. When the number of active material layers is large, a battery with a larger capacity can be obtained. Also, when the number of active material layers is small, the battery can be thinned and made to have excellent flexibility. When the number of active material layers is large, a battery with a larger capacity can be obtained. Also, when the number of active material layers is small, the battery can be thinned and made to have excellent flexibility.

[0160] In the above configuration, the exterior body 509 of the battery can be deformed so that the minimum radius of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less. In the above configuration, the exterior body 509 of the battery can be deformed so that the minimum radius of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less. The film that is the exterior body of the secondary battery is composed of one or two sheets. In the case of a laminated battery, the cross-sectional structure of the curved battery is a structure sandwiched between two curves of the film that is the exterior body. The film that is the exterior body of the secondary battery is composed of one or two sheets. In the case of a laminated battery, the cross-sectional structure of the curved battery is a structure sandwiched between two curves of the film that is the exterior body. The film that is the exterior body of the secondary battery is composed of one or two sheets. In the case of a laminated battery, the cross-sectional structure of the curved battery is a structure sandwiched between two curves of the film that is the exterior body.

[0161] The radius of curvature of the surface will be described with reference to FIG. 10. In FIG. 10(A), in the plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated by an arc of a circle, the radius of the circle is taken as the radius of curvature 1703, and the center of the circle is taken as the center of curvature 1704. The radius of curvature of the surface will be described with reference to FIG. 10. In FIG. 10(A), in the plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated by an arc of a circle, the radius of the circle is taken as the radius of curvature 1703, and the center of the circle is taken as the center of curvature 1704. The radius of curvature of the surface will be described with reference to FIG. 10. In FIG. 10(A), in the plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated by an arc of a circle, the radius of the circle is taken as the radius of curvature 1703, and the center of the circle is taken as the center of curvature 1704. The radius of curvature of the surface will be described with reference to FIG. 10. In FIG. 10(A), in the plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated by an arc of a circle, the radius of the circle is taken as the radius of curvature 1703, and the center of the circle is taken as the center of curvature 1704. A top view of the curved surface 1700 is shown in FIG. 10(B). A cross-sectional view of the curved surface 1700 cut by the plane 1701 is shown in FIG. 10(C). When the curved surface is cut by a plane, the angle of the plane with respect to the curved surface Depending on the cutting position, the radius of curvature of the curve appearing in the cross section will be different. In this specification, etc., the smallest radius of curvature is taken as the radius of curvature of the surface.

[0162] When a secondary battery with two films as an exterior body sandwiching 1805 such as an electrode and an electrolyte is curved, the radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery is smaller than the radius of curvature 1804 of the film 1803 on the side farther from the center of curvature 1800 ( Fig. 11(A)). When the secondary battery is curved so that the cross section is arc-shaped, a compressive stress is applied to the surface of the film close to the center of curvature 1800, and a tensile stress is applied to the surface of the film far from the center of curvature 1800 (Fig. 11(B)). When a pattern formed by a concave portion or a convex portion is formed on the surface of the exterior body, even if such compressive stress and tensile stress are applied, the influence due to strain can be suppressed within an allowable range. Therefore, the secondary battery has a minimum radius of curvature of the exterior body on the side closer to the center of curvature which can be deformed so as to be, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 m m or less. Note that the cross-sectional shape of the secondary battery is not limited to a simple arc shape, and can be a shape having a part of an arc, for example, the shape shown in Fig. 11(C), a wave shape (Fig. 11(D)), an S shape, etc. When the curved surface of the secondary battery has a shape having a plurality of centers of curvature, in the case where the curved surface having the smallest radius of curvature among the radii of curvature at each of the plurality of centers of curvature,

[0163] it can be deformed so that the minimum radius of curvature of the exterior body closer to the center of curvature of the two exterior bodies is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less.

[0164] ​​​​Next, various examples of lamination of the positive electrode, the negative electrode and the separator are shown.

[0165] FIG. 14A shows an example in which six layers of positive electrodes 111 and six layers of negative electrodes 115 are stacked. A positive electrode active material layer 122 is provided on one surface of a positive electrode current collector 121 of the electrode 111. The negative electrode 115 has a negative electrode current collector 125 on one surface of which a negative electrode active material layer 126 is provided.

[0166] In the configuration shown in FIG. 14(A), the positive electrode 111 does not have a positive electrode active material layer 122. The positive electrode 115 is placed on the positive electrode 11 so that the surfaces of the negative electrode 115 that do not have the negative electrode active material layer 126 are in contact with each other. 1 and the negative electrode 115 are laminated in this order. The surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 122 are called the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 126. The contact surface between the metals can be created by the active material and the separator. The coefficient of friction can be reduced compared to the contact surface of the other surface.

[0167] Therefore, when the storage battery 500 is curved, the positive electrode 111 does not have the positive electrode active material layer 122. The surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 126 slide against each other, so that the inner diameter of the curve and The stress caused by the difference in the outer diameter can be released. When the storage battery 500 is bent, the exterior body 509 of the storage battery 500 is located on the inside of the bent portion. This refers to the radius of curvature of the surface that is in contact with the battery. Therefore, deterioration of the storage battery 500 can be suppressed. Moreover, the storage battery 500 can be made highly reliable.

[0168] FIG. 14(B) shows an example of lamination of a positive electrode 111 and a negative electrode 115 different from that shown in FIG. 14(A). In the configuration shown in FIG. 14(B), a positive electrode active material layer 122 is provided on both sides of a positive electrode current collector 121. In this regard, it is different from the configuration shown in FIG. 14(A). As shown in FIG. 14(B), by providing the positive electrode active material layer 122 on both sides of the positive electrode current collector 121, the capacity per unit volume of the storage battery 500 can be increased.

[0169] Further, FIG. 14(C) shows an example of the lamination of the positive electrode 111 and the negative electrode 115 different from that in FIG. 14(B). In the configuration shown in FIG. 14(C), it is different from the configuration shown in FIG. 14(B) in that the negative electrode active material layer 126 is provided on both sides of the negative electrode current collector 125. As shown in FIG. 14(C), by providing the negative electrode active material layer 126 on both sides of the negative electrode current collector 125, the capacity per unit volume of the storage battery 500 can be further increased.

[0170] Further, in the configuration shown in FIG. 14, the separator 123 wraps the positive electrode 111 in a bag shape, but the present invention is not limited to this. Here, FIG. 15(A) shows an example having a separator 123 with a configuration different from that in FIG. 14(A). In the configuration shown in FIG. 15(A), a sheet-like separator 123 is provided one by one between the positive electrode active material layer 122 and the negative electrode active material layer 126, which is different from the configuration shown in FIG. 14(A). In the configuration shown in FIG. 15(A), the positive electrode 111 and the negative electrode 115 are laminated six layers each, and six layers of the separator 123 are provided.

[0171] Further, FIG. 15(B) shows an example in which a separator 123 different from that in FIG. 15(A) is provided. In the configuration shown in FIG. 15(B), it is different from the configuration shown in FIG. 15(A) in that one separator 123 is folded back multiple times so as to be sandwiched between the positive electrode active material layer 122 and the negative electrode active material layer 126. Also, the configuration of FIG. 15(B) is such that each layer separator shown in the configuration of FIG. 15(A) is separated It can also be said that the structure is formed by extending the separator 123 to connect the layers. As shown in Fig. 15(B), in the structure, six layers of the positive electrode 111 and six layers of the negative electrode 115 are stacked, and the separator 123 needs to be folded back at least five times. Further, the separator 123 is not only provided so as to be sandwiched between the positive electrode active material layer 122 and the negative electrode active material layer 126, but may also be extended to bundle a plurality of the positive electrodes 111 and the negative electrodes 115 together.

[0172] Also, as shown in Fig. 16, the positive electrode, the negative electrode, and the separator may be stacked. Fig. 16(A) is a cross-sectional view of the first electrode assembly 130, and Fig. 16(B) is a cross-sectional view of the second electrode assembly 131. Fig. 16(C) is a cross-sectional view taken along the dashed line A1 - A2 in Fig. 5. Note that in Fig. 16(C), for clarity of the drawing, the first electrode assembly 130, the second electrode assembly 131, and the separator 123 are shown in an extracted manner.

[0173] As shown in Fig. 16(C), the storage battery 500 has a plurality of the first electrode assemblies 130 and a plurality of the second electrode assemblies 131.

[0174] As shown in Fig. 16(A), in the first electrode assembly 130, a positive electrode 111a having a positive electrode active material layer 122 on both sides of the positive electrode current collector 121, the separator 123, a negative electrode 115a having a negative electrode active material layer 126 on both sides of the negative electrode current collector 125, the separator 123, and a positive electrode 111a having a positive electrode active material layer 122 on both sides of the positive electrode current collector 121 are stacked in this order. Also, as shown in Fig. 16( B), in the second electrode assembly 131, a negative electrode 115a having a negative electrode active material layer 126 on both sides of the negative electrode current collector 125, the separator 123, a positive electrode current collector 121 having a positive electrode active The positive electrode 111a having the quality layer 122, the separator 123, and the negative electrode active material layer 126 are laminated in this order on both sides of the negative electrode current collector 125.

[0175] Furthermore, as shown in Fig. 16(C), the plurality of first electrode assemblies 130 and the plurality of second electrode assemblies 131 are covered by the wound separator 123.

[0176] [Coin-type battery] Next, as an example of the power storage device, an example of a coin-type battery will be described with reference to Fig. 12. Fig. 12(A) is an external view of a coin-type (single-layer flat-type) battery, and Fig. 12(B) is its cross-sectional view.

[0177] The coin-type battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal, which are insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact therewith. formed by

[0178] Also, the negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact therewith.

[0179] For the positive electrode 304, refer to the description of the positive electrode 503. For the positive electrode active material layer 306, refer to the positive electrode active material layer 502. For the negative electrode 307, refer to the description of the negative electrode 506. For the negative electrode active material layer 309, refer to the description of the negative electrode active material layer 505. For the separator 310, refer to the description of the separator 507. For the electrolytic solution, refer to the description of the electrolytic solution 508.

[0180] Note that for the positive electrode 304 and the negative electrode 307 used in the coin-type storage battery 300, the active material layers may be formed on only one side.

[0181] For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, titanium, etc. that are corrosion-resistant to the electrolyte, or alloys of these or alloys of these and other metals (e.g., stainless steel, etc.) can be used. Also, in order to prevent corrosion by the electrolyte, it is preferable to coat with nickel, aluminum, etc. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 307 respectively.

[0182] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with the electrolyte, and as shown in FIG. 12(B), with the positive electrode can 301 facing downwards, the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are laminated in this order, and the positive electrode can 301 and the negative electrode can 302 are crimped via the gasket 303 to manufacture the coin-type storage battery 300.

[0183] [Cylindrical Storage Battery] Next, as an example of the power storage device, a cylindrical storage battery is shown. The cylindrical storage battery will be described with reference to FIG. 13. The cylindrical storage battery 600 has a positive electrode cap (battery lid) 601 on the upper surface and a battery can (outer can) 602 on the side surface and the bottom surface as shown in FIG. 13(A). The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

[0184] FIG. 13(B) is a diagram schematically showing a cross-section of the cylindrical storage battery. Inside the hollow cylindrical battery can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are sandwiching a separator 605 therebetween. A wound battery element is provided. Although not shown, the battery element is wound around a center pin. The battery can 602 is closed at one end and open at the other end. The material is nickel, aluminum, titanium, or other metals that are resistant to corrosion by the electrolyte. These and their alloys with other metals (e.g., stainless steel, etc.) can be used. In addition, in order to prevent corrosion by the electrolyte, it is preferable to coat the electrode with nickel, aluminum, or the like. A battery element in which a positive electrode, a negative electrode, and a separator are wound inside a battery can 602. The battery element is sandwiched between a pair of opposing insulating plates 608 and 609. A non-aqueous electrolyte (not shown) is poured into the battery can 602. A coin-type storage battery or the like can be used.

[0185] The positive electrode 604 may be referred to as the positive electrode 503. The negative electrode 606 may be referred to as the negative electrode 506. The positive electrode 604 and the negative electrode 606 may be formed by the method for preparing the electrodes shown in, for example, Embodiment 2. The positive and negative electrodes used in cylindrical storage batteries are wound, It is preferable to form an active material on both sides of the current collector. A negative electrode (negative electrode current collecting lead) 607 is connected to the negative electrode 606. The positive electrode terminal 603 and the negative electrode terminal 607 are both made of a metal material such as aluminum. The positive terminal 603 is connected to a safety valve mechanism 612, and the negative terminal 607 is connected to a battery can 602. The safety valve mechanism 612 is a positive temperature coefficient (PTC) element. Temperature Coefficient) 611 via the positive electrode cap 601 is electrically connected. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery rises beyond a predetermined threshold value. Also , when the case occurs, it disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604. Also , the PTC element 611 is a thermosensitive resistance element whose resistance increases when the temperature rises, and it restricts the current amount due to the increase in resistance to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO3)-based semiconductor ceramics or the like can be used.

[0186] When winding the electrodes like a cylindrical storage battery as shown in FIG. 13, a large stress acts on the electrodes during winding. Also, when the wound body of the electrodes is housed in the housing, a stress always acts on the electrodes toward the outside of the winding axis . Even if such a large stress acts on the electrodes, it is possible to prevent the active material from splitting.

[0187] In this embodiment, coin-type, cylindrical, and thin-type storage batteries are shown as the storage battery, but storage batteries of various shapes such as other sealed storage batteries and rectangular storage batteries can be used. Also, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which a positive electrode, a negative electrode, and a separator are wound may be used. For example, examples of other storage batteries are shown in FIGS. 17 to 21 .

[0188] [Configuration Example of Thin-Type Storage Battery] FIGS. 17 and 18 show a configuration example of a thin-type storage battery. The wound body 99 3 shown in FIG. 17(A) has a negative electrode 994, a positive electrode 995, and a separator 996.

[0189] In the wound body 993, the negative electrode 994 and the positive electrode 995 overlap and are laminated with the separator 996 interposed therebetween, and the laminated sheet is wound. This wound body 993 is placed in a rectangular sealed container etc ​ A rectangular secondary battery is manufactured by covering it.

[0190] Note that the number of layers of the laminate composed of the negative electrode 994, the positive electrode 995, and the separator 996 may be appropriately designed according to the required capacity and the element volume. The negative electrode 994 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 997 and 998, and the positive electrode 995 is connected to a positive electrode current collector (not shown) via the other of the lead electrodes 997 and 998. .

[0191] The storage battery 990 shown in FIGS. 17(B) and 17(C) is formed by thermocompression bonding or the like a film 981 serving as an exterior body and a film 982 having a concave portion, and storing the above-described wound body 993 in the space formed thereby. The wound body 993 has lead electrodes 997 and 998 and is impregnated with an electrolytic solution inside the film 981 and the film 982 having a concave portion.

[0192] For the film 981 and the film 982 having a concave portion, a metal material such as aluminum or a resin material can be used. If a resin material is used as the material of the film 981 and the film 982 having a concave portion, the film 981 and the film 982 having a concave portion can be deformed when an external force is applied, and a flexible storage battery can be manufactured.

[0193] In addition, FIGS. 17(B) and 17(C) show an example using two films, but a space may be formed by bending one film, and the above-described wound body 993 may be stored in the space.

[0194] Also, a power storage device can be manufactured by using a resin material or the like for the exterior body or the sealing container of the power storage device to make it flexible. However, when using a resin material for the exterior body or the sealing container, the portion for external connection shall be made of a conductive material.

[0195] For example, an example of another thin flexible battery is shown in FIG. 18. Since the wound body 9 93 shown in FIG. 18(A) is the same as that shown in FIG. 17(A), detailed description thereof will be omitted. .

[0196] The batteries 990 shown in FIGS. 18(B) and 18(C) house the wound body 993 described above inside the exterior body 991. The wound body 993 has lead electrodes 997 and lead electrode 998, and is impregnated with the electrolytic solution inside the exterior bodies 991, 992. The exterior bodies 991, 992 can be made of a metal material such as aluminum or a resin material. If a resin material is used as the material of the exterior bodies 991, 992, the exterior bodies 9 91, 992 can be deformed when a force is applied from the outside, and a thin flexible battery can be manufactured.

[0197] By using the electrode containing the active material according to one aspect of the present invention in a thin flexible battery, even if stress acts on the electrode by repeatedly bending the thin flexible battery, it is possible to prevent the active material from splitting.

[0198] As described above, by using an electrode with an active material covered with graphene on at least a part of the cleavage surface, it is possible to suppress a decrease in the voltage of the battery and a decrease in the discharge capacity. Thereby, the cycle characteristics of the battery accompanying charge and discharge can be improved.

[0199] [Structural Example of Power Storage System] Also, a structural example of the power storage system will be described with reference to FIGS. 19 to 21. Here, the power storage system refers to, for example, a device equipped with a power storage device.

[0200] FIGS. 19(A) and 19(B) are diagrams showing the external views of the power storage system. The power storage system has a circuit board 900 and a storage battery 913. A label 91 0 is attached to the storage battery 913. Further, as shown in FIG. 19(B), the power storage system has a terminal 951 , a terminal 952, an antenna 914, and an antenna 915.

[0201] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 95 1, the terminal 952, the antenna 914, the antenna 915, and the circuit 912. In addition, a plurality of terminals 911 may be provided, and each of the plurality of terminals 911 may be used as a control signal input terminal, a power supply terminal, etc.

[0202] The circuit 912 may be provided on the back surface of the circuit board 900. Note that the antennas 914 and 915 are not limited to a coil shape, and may be, for example, linear or plate-shaped. Also plane antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, inductive body antennas, or other antennas may be used. Alternatively, the antenna 914 or the antenna 91 5 may be a flat plate-shaped conductor. This flat plate-shaped conductor can function as one of the conductors for electric field coupling. That is, the antenna 914 or the antenna 91 5 may be made to function as one of the two conductors of the capacitor. Thereby, not only electromagnetic fields and magnetic fields but also power exchange can be performed by the electric field.

[0203] The line width of antenna 914 is preferably larger than the line width of antenna 915. Thereby, the amount of power received by antenna 914 can be increased.

[0204] The power storage system has a layer 9 16 between antenna 914 and antenna 915 and the storage battery 913. The layer 916 has a function that can shield the electromagnetic field by the storage battery 913, for example. As the layer 916,

[0205] a magnetic material can be used, for example.

[0206] Note that the structure of the power storage system is not limited to the structure shown in FIG. 19. For example, as shown in FIGS. 20(A-1) and 20(A-2), antennas may be provided on each of a pair of opposing surfaces of the storage battery 913 shown in FIGS. 19(A) and 19(B). FIG. 20(A-1) is an external view seen from one side direction of the pair of surfaces, and FIG. 2 0(A-2) is an external view seen from the other side direction of the pair of surfaces. Note that, for the same parts as those of the power storage system shown in FIGS. 19(A) and 19(B), the description of the power storage system shown in FIGS. 19(A) and 1 9(B) can be appropriately incorporated.

[0207] As shown in FIG. 20(A-1), antenna 914 is provided with layer 916 interposed therebetween on one of the pair of surfaces of storage battery 913, and as shown in FIG. 20(A-2), antenna 915 is provided with layer 917 interposed therebetween on the other of the pair of surfaces of storage battery 913. The layer 917 has a function that can shield the electromagnetic field by the storage battery 913, for example. As the layer 917, a magnetic material can be used, for example.

[0208] By adopting the above structure, the sizes of both the antenna 914 and the antenna 915 can be increased.

[0209] Alternatively, as shown in FIGS. 20(B-1) and 20(B-2), another antenna may be provided on each of a pair of opposing surfaces of the storage battery 913 shown in FIGS. 19(A) and 19(B). FIG. 20(B-1) is an external view seen from one side direction of the pair of surfaces, and FIG. 20(B-2) is an external view seen from the other side direction of the pair of surfaces. Note that, for the same parts as those of the power storage system shown in FIGS. 19(A) and 19(B), the description of the power storage system shown in FIGS. 19(A) and 19(B) can be appropriately incorporated by reference.

[0210] As shown in FIG. 20(B-1), the antennas 914 and 915 are provided with a layer 916 interposed therebetween on one of the pair of surfaces of the storage battery 913, and as shown in FIG. 20(B-2), the antenna 918 is provided with a layer 917 interposed therebetween on the other of the pair of surfaces of the storage battery 913. The antenna 91 8 has, for example, a function capable of performing data communication with an external device. For the antenna 91 8, an antenna having a shape applicable to, for example, the antennas 914 and 915 can be applied. As a communication method between the power storage system and another device via the antenna 918, a response method or the like that can be used between the power storage system and another device, such as NFC, can be applied.

[0211] Alternatively, as shown in FIG. 21(A), a display device 920 may be provided on the storage battery 91 3 shown in FIGS. 19(A) and 19(B). The display device 920 is electrically connected to the terminal 911 via the terminal 919. Note that a label 910 is not provided at the portion where the display device 920 is provided. ​​​​​​ It may be. Regarding the same parts as the power storage system shown in FIGS. 19(A) and 19(B), the description of the power storage system shown in FIGS. 19(A) and 19(B) can be appropriately incorporated.

[0212] The display device 920 may display, for example, an image indicating whether it is charging or not, an image indicating the power storage amount, etc. As the display device 920, for example, an electronic paper, a liquid crystal display device, an electroluminescence (also referred to as EL) display device, etc. can be used. For example, by using an electronic paper, the power consumption of the display device 920 can be reduced.

[0213] Alternatively, as shown in FIG. 21(B), a sensor 921 may be provided in the storage battery 913 shown in FIGS. 19(A) and 19(B). The sensor 921 is electrically connected to the terminal 911 via the terminal 922. Regarding the same parts as the power storage system shown in FIGS. 19(A) and 19(B), the description of the power storage system shown in FIGS. 19(A) and 19(B) can be appropriately incorporated.

[0214] As the sensor 921, for example, those including a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation rays, flow rate, humidity, gradient, vibration, odor or infrared rays can be used. By providing the sensor 921, for example, data (such as temperature) indicating the environment where the power storage system is placed can be detected and stored in the memory in the circuit 912.

[0215] In the storage battery and the power storage system shown in this embodiment, an electrode according to one aspect of the present invention is used. Therefore, the capacity of the storage battery and the energy storage system can be increased. Also, the energy density can be increased. Also, the reliability can be improved. Also, the lifespan can be extended. Also, the reliability can be improved. Also, the lifespan can be extended.

[0216] This embodiment can be implemented in appropriate combination with other embodiments.

[0217] (Embodiment 4) In this embodiment, an example of mounting a flexible storage battery on an electronic device will be described.

[0218] An example of mounting the flexible storage battery shown in Embodiment 3 on an electronic device is shown in FIG. 22. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned. As an electronic device to which a storage device having a flexible shape is applied, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, an audio playback device, a large game machine such as a pachinko machine, etc. can be mentioned.

[0219] Also, it is possible to incorporate a storage device having a flexible shape along the inner wall or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile. Also, it is possible to incorporate a storage device having a flexible shape along the inner wall or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile.

[0220] FIG. 22(A) shows an example of a mobile phone. The mobile phone 7400 includes, in addition to a display unit 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 has a storage device 7407. FIG. 22(A) shows an example of a mobile phone. The mobile phone 7400 includes, in addition to a display unit 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 has a storage device 7407. FIG. 22(A) shows an example of a mobile phone. The mobile phone 7400 includes, in addition to a display unit 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 has a storage device 7407. FIG. 22(A) shows an example of a mobile phone. The mobile phone 7400 includes, in addition to a display unit 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Note that the mobile phone 7400 has a storage device 7407.

[0221] ​Figure 22(B) shows the state in which the mobile phone 7400 is bent. When the mobile phone 74 00 is deformed by an external force and the whole is bent, the power storage device 7407 provided inside it is also bent. Also, at that time, the state of the bent power storage device 7407 is shown in Fig. 22( C). The power storage device 7407 is a thin battery. The power storage device 7407 is fixed in a bent state. Incidentally, the power storage device 7407 has a lead electrode 7408 electrically connected to the current collector 7409. For example, the current collector 7409 is a copper foil, and is alloyed with a part of gallium to improve the adhesion to the active material layer in contact with the current collector 7409, and the power storage device 7407 has a high-reliability configuration in a bent state. For example, the current collector 7409 is a copper foil, and is alloyed with a part of gallium to improve the adhesion to the active material layer in contact with the current collector 7409, and the power storage device 7407 has a high-reliability configuration in a bent state. has a high-reliability configuration in a bent state.

[0222] Figure 22(D) shows an example of a bangle-type display device. The portable display device 7100 includes a housing 7101, a display unit 7102, an operation button 7103, and a power storage device 7104. Also, Fig. 22(E) shows the state of the bent power storage device 7104. When the power storage device 7104 is bent and worn on the user's arm, the housing deforms and the curvature of part or even all of the power storage device 7104 changes. Incidentally, the value representing the degree of bending at an arbitrary point on the curve by the radius of the corresponding circle is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, part or even all of the main surface of the housing or the power storage device 7104 changes within the range where the radius of curvature is 40 mm or more and 150 mm or less. If the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 15 0 mm or less, high reliability can be maintained. 0 mm or less, high reliability can be maintained. or all changes. If the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 15 0 mm or less, high reliability can be maintained.

[0223] Figure 22(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 It includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, operation buttons 7 205, input / output terminals 7206, etc.

[0224] The portable information terminal 7200 can execute various applications such as mobile phones, e-mails, text viewing and creation, music playback, in ternet communication, computer games, etc. It is possible.

[0225] The display surface of the display unit 7202 is provided in a curved shape, and the display can be performed along the curved display surface. In addition, the display unit 7202 is provided with a touch sensor, and can be operated by touching the screen with a finger or a stylus, etc. For example, by touching the icon 7 207 displayed on the display unit 7202, an application can be launched.

[0226] In addition to time setting, the operation buttons 7205 can have various functions such as turning on and off the power, turning on and off wireless communication, executing and canceling the manner mode, executing and canceling the power saving mode, etc. For example, the functions of the operation buttons 7205 can also be freely set by the operating system incorporated in the portable information terminal 7200.

[0227] In addition, the portable information terminal 7200 can execute communication-standardized short-range wireless communication. For example, by communicating with a wireless communication-enabled headset, it is also possible to make a hands-free call.

[0228] In addition, the portable information terminal 7200 is provided with input / output terminals 7206, and can directly exchange data with other information terminals via a connector. In addition, charging can be performed via the input / output terminals 7206. It is also possible to perform electricity. Note that the charging operation can be performed by wireless power supply without going through the input / output terminal 7206. It may be performed.

[0229] The display unit 7202 of the portable information terminal 7200 has a power storage device including the electrodes according to one aspect of the present invention. For example, the power storage device 7104 shown in FIG. 22(E) can be incorporated inside the housing 7201 in a curved state or in a state where it can be curved inside the band 7203. It can be incorporated.

[0230] The portable information terminal 7200 preferably has a sensor. Examples of the sensor include human sensors such as a fingerprint sensor, a pulse sensor, and a body temperature sensor, and a touch sensor, a pressure sensor, and an acceleration sensor. It is preferable that such sensors are mounted. For example, a fingerprint sensor, a pulse sensor, a body temperature sensor, and other human sensors, a touch sensor, a pressure sensor, an acceleration sensor, etc. are preferably mounted.

[0231] FIG. 22(G) shows an example of a bracelet-type display device. The display device 7300 has a display unit 7304 and has a power storage device according to one aspect of the present invention. In addition, the display device 7300 can also be provided with a touch sensor on the display unit 7304 and can also function as a portable information terminal.

[0232] The display surface of the display unit 7304 is curved, and display can be performed along the curved display surface. In addition, the display device 7300 can change the display situation by short-range wireless communication conforming to a communication standard or the like.

[0233] In addition, the display device 7300 is provided with input / output terminals and can directly exchange data with other information terminals via a connector. It can also be charged via the input / output terminals. Note that the charging operation may be performed by wireless power supply without going through the input / output terminals.

[0234] ​​​​​​This embodiment can be implemented in appropriate combination with other embodiments.

[0235] (Embodiment 5) In this embodiment, an example of an electronic device capable of mounting a power storage device is shown.

[0236] FIGS. 23(A) and 23(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 23(A) and 23(B) includes a housing 9630a, a housing 9630b, a movable part 9640 connecting the housing 9630a and the housing 9630b, a display unit 9 631a and a display unit 9631 having a display unit 9631b, a display mode changeover switch 96 26, a power switch 9627, a power saving mode changeover switch 9625, a fastener 9629 , and an operation switch 9628. FIG. 23(A) shows the tablet terminal 9600 in an open state, and FIG. 23(B) shows the tablet terminal 9600 in a closed state.

[0237] Further, the tablet terminal 9600 has a power storage body 9635 inside the housing 9630a and the housing 9630b. The power storage body 9635 is provided through the movable part 9640 and extends across the housing 9630a and the housing 9630b.

[0238] A part of the display unit 9631a can be a touch panel area 9632a, and data can be input by touching the displayed operation key 9638. Note that, in the display unit 96 31a, as an example, a configuration in which half of the area has only a display function and the other half of the area has a touch panel function is shown, but the configuration is not limited thereto. The entire area of the display unit 96 31a may have a touch panel function. For example, the display unit 9 31a may be configured such that all areas have a touch panel function. For example, the display unit 9 31a may be configured such that all areas have a touch panel function. For example, the display unit 9 The entire surface of 631a is used as a touch panel with keyboard buttons displayed, and the display unit 9631b is used as a display screen. It can be used.

[0239] Also, in the display unit 9631b, similar to the display unit 9631a, a part of the display unit 9631b can be set as the touch panel area 9632b. Also, when a finger or a stylus touches the position where the keyboard display switching button 9639 of the touch panel is displayed, the keyboard buttons can be displayed on the display unit 9631b.

[0240] Also, simultaneous touch input can be performed on the touch panel area 9632a and the touch panel area 9632b.

[0241] Also, the display mode switching switch 9626 can select to switch the display orientation such as portrait or landscape, and switch between black and white display and color display. The power saving mode switching switch 9625 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal 9600. The tablet terminal may incorporate other detection devices such as sensors that detect inclination, such as a gyro and an acceleration sensor, in addition to the optical sensor.

[0242] Also, in Fig. 23(A), an example where the display areas of the display unit 9631a and the display unit 9631b are the same is shown, but it is not particularly limited. One size and the other size may be different, and the display quality shown may also be different. For example, one may be a display panel that can perform higher-definition display than the other.

[0243] Fig. 23(B) shows a closed state. The tablet terminal includes a housing 9630, a solar cell 9​​​​​​​​​ It has a charge and discharge control circuit 9634 including a DCDC converter 9636. Also, as the power storage body 9635, a power storage body according to an aspect of the present invention is used.

[0244] Since the tablet-type terminal 9600 is foldable in two, the housing 9630a and the housing 9630b can be folded so as to overlap when not in use. By folding, the display units 9631a and 9631b can be protected, so the durability of the tablet-type terminal 9600 can be enhanced. Also, the power storage body 9635 using the power storage body according to an aspect of the present invention has flexibility and is less likely to have a decrease in charge and discharge capacity even when repeatedly bent and stretched. Therefore, a tablet-type terminal with excellent reliability can be provided.

[0245] Also, in addition to this, the tablet-type terminals shown in FIGS. 23(A) and 23(B) can have functions such as displaying various types of information (still images, moving images, text images, etc.), a calendar, a date or time, etc. on the display unit, a touch input function for touch input operation or editing of the information displayed on the display unit, a function of controlling processing by various software (programs), etc.

[0246] Power can be supplied to the touch panel, the display unit, or the video signal processing unit, etc. by the solar cell 9633 mounted on the surface of the tablet-type terminal. The solar cell 9633 can be provided on one side or both sides of the housing 9630, and can be configured to efficiently charge the power storage body 9635. As the power storage body 9635, using a lithium-ion battery has advantages such as enabling miniaturization.

[0247] Next, the configuration and operation of the charge / discharge control circuit 9634 shown in Fig. 23(B) will be described with reference to Fig. 23 (C) by means of a block diagram. Fig. 23(C) shows a solar cell 9633, a power storage element 96 35, a DCDC converter 9636, a converter 9637, switches SW1 to SW3, and a display unit 9631. The power storage element 9635, the DCDC converter 9636, the co nverter 9637, and the switches SW1 to SW3 correspond to the portions of the charge / discharge control circuit 9 634 shown in Fig. 23(B).

[0248] First, an example of the operation when power is generated by the solar cell 9633 due to external light will be described . The power generated by the solar cell is stepped up or down by the DCDC converter 9636 so as to be a voltage for charging the power storage element 9635. When the power from the solar cell 9633 is used for the operation of the display unit 9631, the switch SW1 is turned on, and the converter 963 7 steps up or down the voltage to the voltage required for the display unit 9631. When the display on the display unit 963 1 is not performed, SW1 may be turned off and SW2 may be turned on to charge the power storage element 9635 .

[0249] Note that the solar cell 9633 is shown as an example of a power generation means, but is not particularly limited, and the power storage element 9635 may be charged by other power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). For example, a contactless power transmission module that wirelessly (non-contact) transmits and receives power for charging, or a configuration that combines other charging means may be used .

[0250] Fig. 24 shows an example of another electronic device. In Fig. 24, the display device 8000 is an example of the present invention ​​This is an example of an electronic device using the power storage device 8004 according to one aspect. Specifically, the display device 80 00 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker unit 8003, a power storage device 8004, and the like. The power storage device 8004 according to one aspect of the present invention is provided inside the housing 8001. The display device 8000 can receive power supply from a commercial power source or use the power stored in the power storage device 8004. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8004 according to one aspect of the present invention as an uninterruptible power supply, the display device 8000 can be used when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8004 according to one aspect of the present invention as an uninterruptible power supply, the display device 8000 can be used as an uninterruptible power supply, the display device 8000 can be used .

[0251] The display unit 8002 may include a light-emitting device having a light-emitting element such as a liquid crystal display device or an organic EL element in each pixel, an electrophoretic display device, a DMD (Digital Micromirror Dev ice), a PDP (Plasma Display Panel), a FED (Field Emission Display), or the like, and a semiconductor display device can be used .

[0252] In addition to the display device for receiving TV broadcasts, the display device includes all display devices for information display, such as those for personal computers and advertising displays .

[0253] In FIG. 24, the installed lighting device 8100 is an example of an electronic device using the power storage device 8 103 according to one aspect of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a power storage device 8103, and the like. In FIG. 24, the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8 101 and the light source 8102 are installed is taken as an example Although not shown, the power storage device 8103 may be provided inside the housing 8101. Lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an

[0254] uninterruptible power supply, the lighting device 8100 can be used. In addition, in FIG. 24, an installed lighting device 8100 provided on the ceiling 8104 is exemplified. However, the power storage device according to one aspect of the present invention can also be used for installed lighting devices provided on, for example, side

[0255] walls 8105, floors 8106, windows 8107, etc. other than the ceiling 8104, and can also be used for tabletop lighting devices and the like. In addition, as the light source 8102, an artificial light source that artificially obtains

[0256] light using power can be used. Specifically, incandescent bulbs, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements can be mentioned as an example of the above artificial light source. In FIG. 24, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using the power storage device 8203 according to one aspect of the present invention. Specifically, the indoor unit 8200 includes a housing - can receive power supply from a commercial power source or use the power stored in the power storage device 8203. In particular, when power storage devices 8 203 are provided in both the indoor unit 8200 and the outdoor unit 8204, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8203 according to one aspect of the present invention as an uninterruptible power supply, the air conditioner can be used. In FIG. 24, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated, but the power storage device according to one aspect of the present invention can also be used in an integrated type air conditioner having the functions of the indoor unit and the outdoor unit in one housing.

[0257] In FIG. 24, the electric refrigerator 8300 is an example of an electronic device using the power storage device 8304 according to one aspect of the present invention. Specifically, the electric refrigerator 8300 has a housing 8301, a refrigerator door 8302, a freezer door 8303, a power storage device 8304, etc. In FIG. 24, the power storage device 8304 is provided inside the housing 8301. The electric refrigerator 8300 can receive power supply from a commercial power source or use the power stored in the power storage device 8304. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8304 according to one aspect of the present invention as an uninterruptible power supply, the electric

[0258] refrigerator 8300 can be used. Among the above-mentioned electronic devices, electronic devices such as high-frequency heating devices like microwave ovens and electric rice cookers require high power in a short time. Therefore, they supplement the power that cannot be covered by the commercial power source.

[0259] Among the above-mentioned electronic devices, electronic devices such as high-frequency heating devices like microwave ovens and electric rice cookers require high power in a short time. Therefore, they supplement the power that cannot be covered by the commercial power source. By using the power storage device according to one aspect of the present invention as an auxiliary power source for assistance, an electronic device can prevent the breaker of the commercial power supply from tripping during use.

[0260] In addition, during a time period when the electronic device is not in use, particularly during a time period when the ratio of the amount of power actually used to the total amount of power that can be supplied by the commercial power supply source (referred to as the power utilization rate) is low, by storing power in the power storage device, it is possible to suppress an increase in the power utilization rate outside the above time period. For example, in the case of an electric refrigerator 8300, during the night when the temperature is low and the opening and closing of the refrigerator door 8302 and the freezer door 8303 are not performed, power is stored in the power storage device 8304. And during the day when the temperature rises and the opening and closing of the refrigerator door 8302 and the freezer door 8303 are performed, by using the power storage device 8304 as an auxiliary power source, the power utilization rate during the day can be kept low.

[0261] This embodiment can be implemented in appropriate combination with other embodiments.

[0262] (Embodiment 6) In this embodiment, an example of mounting a power storage device on a vehicle is shown.

[0263] In addition, when a power storage device is mounted on a vehicle, next-generation clean energy vehicles such as hybrid vehicles (HEV), electric vehicles (EV), or plug-in hybrid vehicles (PHEV) can be realized.

[0264] In FIG. 25, a vehicle using one aspect of the present invention is illustrated. The automobile 8400 shown in FIG. 25(A) is an electric vehicle that uses an electric motor as a power source for running. Or a power source for running can appropriately select and use an electric motor and an engine. ​ It is a hybrid vehicle. By using one aspect of the present invention, a vehicle with a long cruising range can be realized. Moreover, the automobile 8400 has a power storage device. The power storage device can not only drive the electric motor 8406, but also supply power to lighting devices such as the headlight 8401 and the room light (not shown).

[0265] In addition, the power storage device can supply power to display devices such as the speedometer and tachometer that the automobile 8400 has. Furthermore, the power storage device can supply power to semiconductor devices such as the navigation system that the automobile 8400 has.

[0266] The automobile 8500 shown in FIG. 25(B) can be charged by receiving power supply from an external charging facility by a plug-in method, a non-contact power supply method, or the like to the power storage device that the automobile 8500 has. FIG. 25(B) shows a state in which charging is being performed from the ground-mounted charging device 8021 to the power storage device 8024 mounted on the automobile 8500 via the cable 8022. When charging, the charging method, the connector standard, etc. may be appropriately performed in a predetermined method such as CHAdeMO (registered trademark) or Combo. The charging device 8021 may be a charging station provided in a commercial facility, or may be a household power source. For example, by plug-in technology, the power storage device 8024 mounted on the automobile 8500 can be charged by external power supply. Charging can be performed by converting AC power into DC power via a conversion device such as an AC / DC converter.

[0267] Moreover, although not shown, a power receiving device is mounted on the vehicle, and power is supplied non-contact from a power transmission device on the ground. In this case, the power transmission device is installed on the road or on the exterior wall. By incorporating this, charging can be done not only when the vehicle is stopped but also while the vehicle is moving. In addition, the vehicle exterior may be provided with a power supply. A solar cell may be provided in the vehicle so that the power storage device can be charged when the vehicle is stopped or traveling. To supply power in the above, an electromagnetic induction method or a magnetic resonance method can be used.

[0268] According to one embodiment of the present invention, the cycle characteristics of a power storage device can be improved, and the reliability can be improved. Furthermore, according to one embodiment of the present invention, the characteristics of the power storage device can be improved, Therefore, the power storage device itself can be made smaller and lighter. This contributes to reducing the weight of the vehicle, which can improve the cruising distance. The on-board power storage device can also be used as a power supply source for something other than the vehicle. This allows avoiding the use of commercial power during peak hours.

[0269] This embodiment mode can be implemented in appropriate combination with other embodiment modes. EXAMPLES

[0270] Example 1 This example describes a method for producing a lithium-containing composite phosphate according to one embodiment of the present invention and analysis results. The results will be explained.

[0271] <Preparation of synthetic products> A lithium-containing composite phosphate was produced based on the flow shown in Figure 2.

[0272] In step S201a, 6.359 g of LiCl was weighed as the lithium compound. . In step S201b, 3.41 ml of H3PO4 was weighed as the phosphorus compound. The molar number of lithium relative to phosphorus was made three times. In step S201d, 50 ml of water was weighed as the solvent.

[0273] Next, in step S205, LiCl and H3PO4 were put into water to form a mixed solution A. Step S205 was carried out in an air atmosphere. When forming the mixed solution, it is preferable to add materials while stirring using a stirrer or the like.

[0274] Next, in step S205b, aqueous ammonia with a concentration of 28% by weight was prepared as solution Q.

[0275] Next, in step S207, solution Q was dropped into the mixed solution A and pH measurement was carried out. Solution Q was dropped until the desired pH was reached to form a mixed solution B. Here, several types of mixed solutions B with different pH values were prepared. For pH measurement, a SevenGo pH meter manufactured by Mettler Toledo was used.

[0276] Next, in step S208, 9.941 g of FeCl2·4H2O was weighed as the M(II) compound. The molar number of iron relative to phosphorus was made one time. Also, in step S209b, water was weighed as the solvent.

[0277] Next, in step S209, for each of several types of mixed solutions B with different pH values, the mixed solution B, FeCl2·4H2O, and water were mixed to form 16 types of solutions shown in Table 1 as the mixed solution C. In Table 1, the pH after step S207 of the mixed solution (mixed solution B) H, the pH of the mixture C after step S209, and the p after step S211 described below H, are shown.

[0278]

Table 1

[0279] Next, in step S211, the mixture C was put into an autoclave apparatus having a fluororesin inner cylinder, and Conditions 1 to 6 shown in Table 1 were heated at 110°C for 1 hour, Cond itions 7 to 12 were heated at 120°C for 1 hour, and Conditions 13 to 16 were heated at 150 °C for 1 hour, respectively. The pressure inside the inner cylinder during heating was approximately 0 .1 MPa to 0.15 MPa at 110°C and approximately 0.4 MPa to 0.5 M Pa at 150°C. After heating, it was left to cool until the temperature decreased, and the composition inside the inner cylinder was filtered and washed with water. The autoclave apparatus used was the Mini Reactor MS200 -C manufactured by Ohm Labtech Co., Ltd. .

[0280] Next, it was dried at 60°C for 2 hours under a reduced-pressure atmosphere to collect Composition A.

[0281] <XRD Measurement> For the obtained Composition A, measurement was performed by the θ-2θ method of XRD. For the measurement, D8 ADVANCE manufactured by Bruker AXS was used.

[0282] The XRD measurement results of Composition A obtained by Conditions 1, 2, 3, 4, 5, and 6 are shown in FIGS. 26(A), (B), FIGS. 27(A), (B), FIGS. 28(A), and (B) , respectively. Also, FIG. 29(A) is an enlarged view of a part of FIG. 27(A), and FIG. 29(B) is an enlarged view of a part of FIG. 26 (B). ​

[0283] In addition, Fig. 30 shows the XRD measurement results of Conditions 7 to 12, and Fig. 31 shows the XRD measurement results of Conditions 13 to 16, respectively.

[0284] In Fig. 29(A), six peaks having maximum values at 17.1°, 20.7°, 25.5°, 29.8°, 32.1 °, and 35.6° were observed, corresponding to the peaks A to F described in Embodiment 1. From these peaks, the obtained composite A was found to correspond to LiFePO4 with a space group of Pnma according to the PDF (Powder Diffraction File)-numbers 0 of the ICDD (International Centre for Diffraction Data ) 01-070-6684. It should be noted that the PDF-numbers 01-070-6684 correspond to the ICSD (Inorganic Crystal Structure Database) Code 92 ) 198. It is thus suggested that it corresponds to LiFePO4 with a space group of Pnma. In addition, the PDF-numbers 01-070-6684 correspond to the ICSD (Inorganic Crystal Structure Database) Code 92 198. It corresponds to 198.

[0285] From the above, even at a low temperature of 110°C in step S211, lithium iron phosphate having an olivine-type structure could be formed by controlling the pH.

[0286] In Fig. 29(A), the maximum values (A1 to F1) of the peaks of peaks A to F were 17. 149°, 20.705°, 25.548°, 29.835°, 32.148°, and 35.561°. Also, the half-widths (A2 to F2) of the peaks were 0.103°, 0 .063°, 0.087°, 0.227°, 0.144°, and 0.139°. . Also, in Condition 9 of FIG. 30, A1 to F1 are 17.097°, 20.716°, 25.527°, 29.773°, 32.107°, and 35.53 0°, and A2 to F2 are 0.0983°, 0.082°, 0.081°, 0.10 8°, 0.087°, and 0.095°. Also, in Condition 10 A1 to F1 are 17.210°, 20.767°, 25.610°, 29.87 6°, 32.189°, and 35.602°, and A2 to F2 are 0.113°, 0.123°, 0.117°, 0.140°, 0.113°, and 0.117° .

[0287] Here, in Table 2, for each Condition, when the peak most strongly observed among the peaks observed by XRD is any one of Peaks A to F shown in the embodiments, it is denoted as W , and when the peak most strongly observed is a peak different from Peaks A to F, it is denoted as X .

[0288]

Table 2

[0289] Here, for example, when analyzing FIG. 29(B) in detail, slightly weak peaks are observed, suggesting correspondence with Peaks B, C, and F. Therefore, for example, in Condition 2 , although there are many by-products, it is considered that lithium iron phosphate with an olivine-type structure, which is the target compound, is also formed.

[0290] From Table 2, when the pH after Step S209 is less than 5, olivine-type structure It was found that there are conditions under which lithium iron phosphate of the as-prepared form can be obtained. That is, it can be said that by making the mixed solution acidic it becomes easier to obtain lithium iron phosphate having an olivine-type structure. This is considered to be because, as shown in the potential-pH diagram of FIG. 6 in Patent Document 1, when the pH increases and becomes alkaline, Fe(OH)2 and the like are generated. Also, when the pH is 3 or less, it is suggested that it is difficult to obtain lithium iron phosphate having an olivine-type structure in a low-temperature situation. Since lithium iron phosphate dissolves in acid, it is considered that when the pH is too low, it becomes difficult to be generated.

[0291] Also, at 120 °C, compared with the condition where the pH is 5.81, since weak peaks other than lithium iron phosphate having an olivine-type structure are slightly observed under the condition where the pH is 4.97, it is considered that the purity of the crystal is higher under the condition where the pH is 5 .81.

[0292] In FIG. 28(A), peaks are observed at 18.6°, 20.2°, 21.0°, 26.3°, 27.4 °, 30.4°, and 31.7°, and it is suggested that they correspond to the peaks of NH4FeP O4·H2O from the database. Also, in FIG. 28(B), peaks are observed at 22 .4°, 23.3°, 24.9°, 34.0°, and 36.8°, and it is suggested that they correspond to the peaks of Li3PO4 from PDF-number 00-015-0760. It is considered possible that the Li3PO4 used as a raw material remains. Also, the peak observed at 31.7° may correspond to NH4FePO4·H2O from PDF-number 00-045-0424.

[0293] Thus, compared with the conditions of FIG. 29(A), when the pH increases, the target synthetic product Hardly any of the resulting composite A is obtained, and it can be seen that compounds such as Li3PO4 and NH4FePO4·H2O are produced. It can be seen that compounds such as Li3PO4 and NH4FePO4·H2O are produced.

[0294] Next, consider the by-products when the pH is low. From Condition 8 in Figure 30, peaks are observed at 19.8°, 22.3°, 28.7°, 30.9°, 34.5°, etc., which may correspond to FePO4·2H2O with PDF-number 00-033-0667, Fe5P4O with PDF-number 00-045-0121, Fe5P4O with PDF-number 00-045-0121, 20 H 10 and so on. There is a possibility of correspondence.

[0295] <SEM Observation> Next, SEM observation of the obtained composite A was performed. The composite A was obtained as particles. The S -4800 manufactured by Hitachi High-Technologies Corporation was used for SEM observation.

[0296] The SEM observation results of the composite A obtained under Conditions 1, 2, 3, 4, 5, and 6 are shown in Figures 32(A), (B), 33(A), (B), 34(A), and (B), respectively. respectively.

[0297] The SEM observation results of the composite A obtained under Conditions 7, 8, 9, 10, 11, and 12 are shown in Figures 35(A), (B), 36(A), (B), 37(A), and (B), respectively. (B), respectively.

[0298] The SEM observation results of the composite A obtained under Conditions 13, 14, 15, and 16 are shown in Figures 38(A), (B), 39(A), and (B), respectively. respectively.

[0299] The lower the processing temperature in step S211, the more likely the particles of the resulting composite A are to have a flat shape This can be seen. As an example where the processing temperature is 110 °C, FIG. 33(A) shows an example of the thickness 667 and an example of the length 666 of composite A. The thickness 667 was about 80 nm and the length 66 6 was about 750 nm. Here, the ratio of the thickness 667 to the length 666 may be referred to as the aspect ratio In the example shown in FIG. 33(A), the aspect ratio is small, for example 0.2 or less. FIG. 36(A) shows the observation result of composite A when the processing temperature is 120 °C. It can be seen from FIG 33(A) that, compared with FIG. 36(A), flatter (thinner) particles are obtained It can also be seen that when the pH is high, as shown in an example in FIG. 37(B), spherical fine particles having a particle size of about 100 nm and an aspect ratio close to 1 are obtained. On the other hand, when the pH is low, angular particles are obtained, and as the processing temperature decreases, the aspect ratio becomes small. Here, the aspect ratio is, for example, 0.02 or more and 0.45 or less, or 0.05 or more and 0.3 or less.

Explanation of Reference Numerals

[0300] 103 Active material 111 Positive electrode 111a Positive electrode 115 Negative electrode 115a Negative electrode 121 Positive electrode current collector 122 Positive electrode active material layer 123 Separator 125 Negative electrode current collector 126 Negative electrode active material layer 130 Electrode assembly 131 Electrode assembly 300 Storage battery 301 Positive electrode can 302 Negative electrode can 303 Gasket ​304 Positive electrode 305 Positive current collector 306 Positive active material layer 307 Negative electrode 308 Negative current collector 309 Negative active material layer 310 Separator 321 Graphene compound 500 Storage battery 501 Positive current collector 502 Positive active material layer 503 Positive electrode 504 Negative current collector 505 Negative active material layer 506 Negative electrode 507 Separator 508 Electrolyte 509 Outer package 510 Positive lead electrode 511 Negative lead electrode 512 Welding area 514 Sealing part 600 Storage battery 601 Positive cap 602 Battery can 603 Positive terminal 604 Positive electrode 605 Separator 606 Negative electrode 607 Negative terminal 608 Insulating board 609 Insulating board 611 PTC element 612 Safety valve mechanism 666 Length 667 Thickness 900 Circuit board 910 Label 911 Terminal 912 Circuit 913 Storage battery 914 Antenna 915 Antenna 916 Layer 917 Layer 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 951 Terminal 952 Terminal 981 Film 982 Film 990 Storage Battery 991 Exterior Body 992 Exterior Body 993 Wound Body 994 Negative Electrode 995 Positive Electrode 996 Separator 997 Lead Electrode 998 Lead Electrode 1700 Curved Surface 1701 Plane 1702 Curve 1703 Radius of Curvature 1704 Center of Curvature 1800 Center of Curvature 1801 Film 1802 Radius of Curvature 1803 Film 1804 Radius of Curvature 7100 Portable Display Device 7101 Housing 7102 Display Unit 7103 Operation Button 7104 Power Storage Device 7200 Portable Information Terminal 7201 Housing 7202 Display Unit 7203 Band 7204 Buckle 7205 Operation Button 7206 Input / Output Terminal 7207 Icon 7300 Display Device 7304 Display Unit 7400 Mobile Phone 7401 Housing 7402 Display Unit 7403 Operation Button 7404 External Connection Port 7405 Speaker 7406 Microphone 7407 Energy storage device 7408 Lead electrode 7409 Current collector 8000 Display device 8001 Housing 8002 Display unit 8003 Speaker unit 8004 Energy storage device 8021 Charging device 8022 Cable 8024 Energy storage device 8100 Lighting device 8101 Housing 8102 Light source 8103 Energy storage device 8104 Ceiling 8105 Side wall 8106 Floor 8107 Window 8200 Indoor unit 8201 Housing 8202 Air outlet 8203 Energy storage device 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Housing 8302 Door for refrigerator compartment 8303 Door for freezer compartment 8304 Energy storage device 8400 Automobile 8401 Headlight 8406 Electric motor 8500 Automobile 9600 Tablet terminal 9625 Switch 9626 Switch 9627 Power switch 9628 Operation switch 9629 Fastener 9630 Housing 9630a Housing 9630b Housing 9631 Display unit 9631a Display unit 9631b Display unit 9632a Area 9632b area 9633 Solar cell 9634 Charge and discharge control circuit 9635 Energy storage element 9636 DC-DC converter 9637 Converter 9638 Operation key 9639 Button 9640 Movable part< / xrd>

Claims

1. A method for producing a positive electrode active material having an olivine-type crystal structure and containing lithium, phosphorus, iron, and oxygen, comprising: a first step of mixing a lithium compound, a phosphorus compound, and water to form a first mixed solution; a second step of adding a first aqueous solution to the first mixed solution to adjust the pH and form a second mixed solution; a third step of mixing an iron compound into the second mixed solution to form a third mixed solution; a fourth step of subjecting the third mixed solution to heat treatment under a pressure of 0.1 MPa or more and 100 MPa or less and at a temperature of 100°C or more and 350°C or less; The method for producing a positive electrode active material, wherein the pH of the third mixed solution is 3.5 or more and 5.0 or less.

2. According to Claim 1, the lithium compound is lithium chloride, the first aqueous solution is alkaline, and the base of the first aqueous solution is ammonia or an organic amine. The method for producing a positive electrode active material.

3. According to Claim 1 or Claim 2, the third step is performed in an air atmosphere. The method for producing a positive electrode active material.

4. According to any one of Claims 1 to 3, the positive electrode active material is particles having a thickness of 10 nm or more and 200 nm or less. The method for producing a positive electrode active material.

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