Lithium ion secondary battery

Abstract

To provide a lithium ion secondary battery that achieves high energy density by increasing the amount of lithium ions per volume and / or per weight of particles having a positive electrode active material.SOLUTION: A particle has a first region, a second region in contact with at least a portion of the surface of the first region and located outside the first region, and a third region in contact with at least a portion of the surface of the second region and located outside the second region, and the first region and the second region contain lithium and oxygen, at least one of the first region and the second region contains manganese, and at least one of the first region and the second region contains an element represented by M, the first region has first crystals with a layered rock salt structure, and the second region has second crystals with a layered rock salt structure, and the orientation of the first crystals and the orientation of the second crystals are different.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, relating to the manufacture or composition of matter, especially One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, an imaging device, a power storage device, or a memory device. In particular, one embodiment of the present invention relates to a power storage device, a driving method thereof, or a manufacturing method thereof. The present invention relates to the structure of a device and a method for manufacturing the same, and in particular to a positive electrode active material for a lithium ion secondary battery. do. [Background technology]

[0002] In recent years, the use of portable electronic devices such as smartphones and tablets has rapidly increased. With growing interest in environmental issues, hybrid and electric cars are gaining attention. The importance of power storage devices, including secondary batteries, is increasing. Examples include batteries, lead-acid batteries, and lithium-ion secondary batteries. Silicon secondary batteries are being actively developed because they have high capacity and can be made small.

[0003] The basic structure of a secondary battery is an electrolyte placed between a positive electrode and a negative electrode. Examples of materials with this property include solid electrolytes and electrolyte solutions. Each of these typically has a configuration including a current collector and an active material layer provided on the current collector. In the case of a lithium-ion secondary battery, a material that can absorb and release lithium is used as the positive electrode. and as the active material of the negative electrode.

[0004] In lithium ion secondary batteries, the positive electrode active material is, for example, Lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4 ), lithium cobalt phosphate (LiCoPO4), lithium nickel phosphate (LiNiP O4), lithium (Li) and iron (Fe), manganese (Mn), cobalt (Co) Phosphate compounds having an olivine structure containing phosphate or nickel (Ni) are known. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-25983 Summary of the Invention [Problem to be solved by the invention]

[0006] One embodiment of the present invention is to increase the capacity per volume or / and per weight of a power storage device. Another object of the present invention is to provide a method for reducing the volume or / and weight of an electrode. One of the challenges is to increase the capacity per unit volume.

[0007] Alternatively, in one embodiment of the present invention, the volume or / and weight of particles having a positive electrode active material Another object of the present invention is to increase the capacity per unit area of ​​a positive electrode active material. Increasing the amount of lithium ions per volume or / and per weight of the particles One of the challenges is to achieve high energy density.

[0008] Alternatively, one embodiment of the present invention is a positive electrode having a positive electrode active material, which is capable of undergoing battery reaction at a higher potential. One of the challenges is to ensure stable response.

[0009] Another embodiment of the present invention is a power storage device in which a capacity decrease during charge and discharge cycles is suppressed. Another object of one embodiment of the present invention is to provide a positive electrode that can be manufactured at low cost. An object is to provide an active material.

[0010] In addition, it has high ionic conductivity and electrical conductivity as a positive electrode active material for lithium ion secondary batteries. Therefore, one aspect of the present invention is to provide a method for manufacturing a semiconductor device having ionic conductivity and / or electrical conductivity. An object of the present invention is to provide a positive electrode active material having high conductivity.

[0011] Another object of one embodiment of the present invention is to provide a method for manufacturing an electrode for a power storage device. Another object of one embodiment of the present invention is to provide a method for manufacturing a positive electrode active material of a secondary battery. It shall be one of the following.

[0012] Another object of one embodiment of the present invention is to provide a novel substance. An object of one embodiment of the present invention is to provide a novel positive electrode active material. An object of one embodiment is to provide novel particles having a positive electrode active material. An object of one embodiment of the present invention is to provide a novel power storage device. An object of the present invention is to provide a novel battery. An object of the present invention is to provide a lithium-ion secondary battery.

[0013] The description of these problems does not preclude the existence of other problems. One embodiment does not necessarily have to solve all of these problems. The subject matter will be self-evident from the description, drawings, claims, etc. It is possible to extract other issues from the drawings, claims, etc. [Means for solving the problem]

[0014] One embodiment of the present invention is a particle having a lithium manganese composite oxide.

[0015] The particle having a lithium manganese composite oxide according to one embodiment of the present invention has a first region and The present invention also provides a method for manufacturing a lithium-manganese composite oxide-containing electrode comprising the steps of: The particles preferably have a third region.

[0016] The second region is in contact with at least a portion of the surface of the first region and is located outside the first region. Here, the outer side means closer to the surface of the particle. The third region is the outer side of the second region. It is preferably in contact with at least a portion of the surface and located outside the second region.

[0017] The particle of one embodiment of the present invention has the second region, and thus the particle of one embodiment of the present invention can store electricity. When used as a positive electrode active material in a battery, the discharge capacity may be improved. In addition, the discharge voltage may be increased.

[0018] The particle of one embodiment of the present invention has the third region, and thus the particle of one embodiment of the present invention can store electricity. When used as a positive electrode active material in a battery, the discharge capacity may be improved. In addition, the discharge voltage may be increased.

[0019] The first region and the second region contain lithium and oxygen. At least one of the first and second regions contains manganese. At least one of the regions has an element M. Here, the element M is lithium, manganese, or the like. Metal elements other than those mentioned above, or silicon and phosphorus are preferred, and Ni, Ga, Fe, Mo , In, Nb, Nd, Co, Sm, Mg, Al, Ti, Cu, or Zn It is more preferable that the metal element is one of silicon and phosphorus, and nickel is particularly preferable. More preferable.

[0020] The first region and the second region may also contain both manganese and the element M. More preferable.

[0021] The third region is a particle having a lithium manganese composite oxide according to one embodiment of the present invention. Preferably, the surface comprises:

[0022] According to one embodiment of the present invention, a power storage device is provided using particles containing a lithium-manganese composite oxide. When fabricated, the third region acts as a catalyst for the battery reaction, e.g., charging and discharging, in addition to the first and second regions. It is preferable that it is more stable than the second region.

[0023] Here, the second region may have a different crystal structure from the first region. The regions may have crystals with a different orientation than the first region, where the different orientations are This means that the orientation of the crystals differs by an angle greater than, for example, 10°.

[0024] For example, the second region has a spinel structure and the first region has a layered rock salt structure. When the second region has a spinel structure, When the particles are used as a positive electrode active material in a storage battery, the discharge capacity can be improved. In addition, the discharge voltage may be increased.

[0025] Preferably, the second region has a different composition from the first region.

[0026] In addition, the manganese contained in the second region has a different valence from that of the manganese contained in the first region. The element M contained in the second region may have a different valence from the element M contained in the first region. It may have.

[0027] Also, there may be a transition layer between the second region and the first region. and the first region may have a mixed layer therebetween.

[0028] One aspect of the present invention is a particle having a lithium manganese composite oxide, which includes a first region and a second region. and a second region, the second region being in contact with at least a portion of the first region and The first and second regions have lithium and oxygen, and at least one of the first and second regions and either one of the first region or the second region has manganese, and at least one of the first region or the second region is represented by M. The first region has a first crystal having a layered rock salt structure, and the second region has The first crystal has a layered rock salt structure, and the {0 0 1} plane of the first crystal is The crystal has {1 0 0} plane, {1 3 -1} plane or {-1 3 1} plane. Here, two parallel faces are particles that are parallel to at least one of the faces. The angle of the normal is preferably 10° or less, more preferably 5° or less, and even more preferably 3° or less. Furthermore, two lines being parallel means that the angle between the two lines is, for example, 10° or less, and more preferably It is preferably 5° or less, and more preferably 3° or less.

[0029] Alternatively, one embodiment of the present invention is a particle having a lithium manganese composite oxide, a first region, a second region, and a third region, the second region being at least a portion of the first region; the third region contacts at least a portion of the second region, and the first region and the second region The regions comprise lithium and oxygen, and at least one of the first region or the second region comprises: manganese, and at least one of the first region and the second region contains an element represented by M. The first region has first crystals having a layered rock salt structure, and the second region has first crystals having a layered rock salt structure. The grains have a second crystal structure, and the orientation of the first crystal and the orientation of the second crystal are different. The third region preferably contains carbon.

[0030] In the above structure, the {0 0 1} plane of the first crystal is the {0 0 1} plane of the second crystal. At least one of the {1 0 0} plane, {1 3 -1} plane, or {-1 3 1} plane It is preferable that the first and second electrodes are parallel to each other.

[0031] Alternatively, one embodiment of the present invention is a particle having a lithium manganese composite oxide, The second region is in contact with at least a portion of the first region, and the first region is in contact with the second region. The first region and the second region have lithium and oxygen, and the first region or the second region At least one of the first region or the second region has manganese, , M, the first region has a first crystal having a layered rock salt structure, and the second region has a The region is a particle having a second crystal with a spinel structure.

[0032] Alternatively, one embodiment of the present invention is a particle having a lithium manganese composite oxide, The second region is in contact with at least a portion of the first region, and the first region is in contact with the second region. The first region and the second region have lithium and oxygen, and the first region or the second region At least one of the first region or the second region has manganese, , M, and the first region has lithium, manganese, element M, and oxygen atoms. The ratio of the number of atoms is expressed as a1:b1:c1:d1, and the second region is composed of lithium, manganese, element M, The atomic ratio of oxygen is expressed as a2:b2:c2:d2, and d1÷(b1+c1)(=A 1) is greater than or equal to 2.2, and d2÷(b2+c2)(=A2) is less than 2.2. In this way, since A2 is smaller than A1, one aspect of the present invention is When the particles are used as a positive electrode active material in a storage battery, the stability against charge and discharge in the second region is In addition, the particles of one embodiment of the present invention can be used to store electricity. When used as a positive electrode active material in a battery, the discharge capacity may be improved. In addition, the discharge voltage may be increased.

[0033] In the above configuration, the third region is in contact with at least a part of the second region. Preferably, the third region comprises carbon.

[0034] In the above configuration, the thickness of the third region is 0.1 nm or more and 30 nm or less. is preferred.

[0035] Alternatively, one embodiment of the present invention is a particle having a lithium manganese composite oxide, The second region is in contact with at least a portion of the first region, and the first region is in contact with the second region. The first region and the second region contain lithium, manganese, an element represented by M, and oxygen. and the atomic ratio of lithium, manganese, element M, and oxygen in the first region is a1:b1: The atomic ratio of lithium, manganese, element M, and oxygen in the second region is represented by c1:d1. is expressed as a2:b2:c2:d2, and d1÷(b1+c1) is 2.2 or more, and d2÷ (b2+c2) is less than 2.2, and the first region has a first crystal having a layered rock salt structure. The second region has a second crystal with a layered rock salt structure, and the first crystal has {0 0 The {1 0 0} plane, {1 3 -1} plane, or {-1 3 1} planes are parallel to at least one of the grains.

[0036] In the above configuration, the second region has a layered region, and the thickness of the layered region is 0.1 It is preferable that the thickness is between 100 nm and 30 nm.

[0037] Another embodiment of the present invention is a secondary battery using a positive electrode including any of the above-described particles. Another embodiment of the present invention is an electronic device equipped with the secondary battery.

[0038] Here, the present invention relates to a storage battery using particles having a lithium manganese composite oxide. When an electric device is produced, the amount of lithium contained in the particles is reduced by a battery reaction, for example, by charging or discharging. For example, when charging, lithium is released as lithium ions, and the particles The amount of lithium contained in the battery decreases, and the amount of decrease varies depending on the depth of charge.

[0039] In one aspect of the present invention, a mixture is prepared by mixing particles, a binder, and a solvent, and the particles are then mixed. has lithium, manganese, element M, and oxygen, and element M is chromium, cobalt, Aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, One or more elements selected from copper, titanium, niobium, silicon, and phosphorus, A mixture layer is formed on a current collector, and the mixture layer is subjected to a heat treatment to form an electrode layer. The electrode layer is made of at least one of lithium, manganese, element M, and oxygen, and a balance. Method for producing an electrode layer having a compound having a bond with at least one element contained in an binder In the above-mentioned structure, the compound contains lithium, manganese, or a small amount of the element M. Preferably, the particles contain at least one of the above and fluorine. It is preferred to have an oxide having manganese, element M, and oxygen.

[0040] Another embodiment of the present invention is an electrode layer provided over a current collector. The electrode layer includes particles and The binder and the solvent are included, and the particles include lithium, manganese, the element M, and oxygen. The element M is chromium, cobalt, aluminum, nickel, iron, magnesium, molyb Select from: nickel, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus. The electrode layer is composed of lithium, manganese, element M, and a small amount of oxygen. A compound having a bond between at least one of the elements and at least one element contained in the binder. In the above structure, the compound is an electrode layer containing lithium, manganese, or Preferably, the particles contain at least one of the elements M and fluorine. It is preferred to have an oxide having lithium, manganese, element M, and oxygen.

[0041] Here, the present invention relates to a storage battery using particles having a lithium manganese composite oxide. When an electric device is produced, the amount of lithium contained in the particles is reduced by a battery reaction, for example, by charging or discharging. For example, when charging, lithium is released as lithium ions, and the particles The amount of lithium contained in the battery decreases, and the amount of decrease varies depending on the depth of charge. [Effects of the Invention]

[0042] According to one embodiment of the present invention, the capacity per volume or / and per weight of a power storage device can be increased. In addition, according to one embodiment of the present invention, the volume or / and weight of the electrode can be The capacity per unit volume can be increased.

[0043] According to one embodiment of the present invention, the positive electrode active material is Furthermore, according to one embodiment of the present invention, the positive electrode active material can be used to increase the capacity per weight. The amount of lithium ions per volume or / and weight of the particles is increased, High energy density can be achieved.

[0044] According to one embodiment of the present invention, a positive electrode having a positive electrode active material can be used to charge a battery at a higher potential. The reaction can be carried out stably.

[0045] According to one embodiment of the present invention, a power storage device in which a decrease in capacity during charge and discharge cycles is suppressed can be provided. According to one embodiment of the present invention, a positive electrode active material that can be produced at low cost can be provided. We can provide quality.

[0046] In addition, the required properties of the positive electrode active material for lithium-ion secondary batteries are ionic conductivity and According to one aspect of the present invention, it is desirable to provide a material having high ionic conductivity and electrical conductivity. And / or, a positive electrode active material having high electrical conductivity can be provided.

[0047] According to one embodiment of the present invention, a method for manufacturing an electrode for a power storage device can be provided. According to one embodiment of the present invention, a method for manufacturing a positive electrode active material for a secondary battery can be provided.

[0048] According to one embodiment of the present invention, a novel substance can be provided. According to one embodiment of the present invention, a novel positive electrode active material can be provided. According to one embodiment of the present invention, novel particles having a positive electrode active material can be provided. A novel power storage device can be provided. Furthermore, one aspect of the present invention provides a novel lithium ion secondary battery. It can be provided.

[0049] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. The above will be made clear from the description, drawings, claims, etc. It is possible to extract other effects from the descriptions in the aspects and claims. [Brief explanation of the drawings]

[0050] [Figure 1] 1 is a flowchart illustrating a method for producing an active material. [Figure 2] FIG. 1 shows particles according to one embodiment of the present invention. [Figure 3] FIG. 1 is a diagram illustrating a crystal structure. [Figure 4] FIG. 1 is a diagram illustrating a crystal structure. [Figure 5] FIG. [Figure 6] FIG. 1 is a diagram illustrating a thin storage battery. [Figure 7] FIG. 2 is a cross-sectional view of an electrode. [Figure 8] FIG. 1 is a diagram illustrating a thin storage battery. [Figure 9] FIG. 1 is a diagram illustrating a thin storage battery. [Figure 10] FIG. 1 is a diagram illustrating a thin storage battery. [Figure 11] FIG. 10 is a diagram illustrating the radius of curvature of a surface. [Figure 12] FIG. 2 is a diagram illustrating the radius of curvature of a film. [Figure 13] FIG. 1 is a diagram illustrating a coin-type storage battery. [Figure 14] FIG. 1 is a diagram illustrating a cylindrical storage battery. [Figure 15] 1A and 1B illustrate examples of power storage devices. [Figure 16] 1A and 1B illustrate examples of power storage devices. [Figure 17] 1A and 1B illustrate examples of power storage devices. [Figure 18] 1A and 1B illustrate examples of power storage devices. [Figure 19] 1A and 1B illustrate examples of power storage devices. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A to 1C illustrate examples of electronic devices. [Figure 22] 1A to 1C illustrate examples of electronic devices. [Figure 23] 1A to 1C illustrate examples of electronic devices. [Figure 24] FIG. 1 is a block diagram illustrating one embodiment of the present invention. [Figure 25] FIG. 1 is a conceptual diagram illustrating one embodiment of the present invention. [Figure 26] FIG. 1 is a circuit diagram illustrating one embodiment of the present invention. [Figure 27] FIG. 1 is a circuit diagram illustrating one embodiment of the present invention. [Figure 28] FIG. 1 is a conceptual diagram illustrating one embodiment of the present invention. [Figure 29] FIG. 1 is a block diagram illustrating one embodiment of the present invention. [Figure 30] 1 is a flowchart illustrating one embodiment of the present invention. [Figure 31] FIG. [Figure 32] 1A to 1C illustrate particles according to one embodiment of the present invention. [Figure 33] FIG. 1 shows the results of EDX measurements. [Figure 34] HAADF-STEM observation results. [Figure 35] Diagram showing electron diffraction. [Figure 36] FIG. [Figure 37] FIG. [Figure 38] FIG. [Figure 39] Transmission electron microscope observation results. [Figure 40] Transmission electron microscope observation results. [Figure 41] Diagram showing electron diffraction. [Figure 42] FIG. [Figure 43] Scanning electron microscope observation results. [Figure 44] Scanning electron microscope observation results. [Figure 45] FIG. 10 is a graph showing the relationship between the number of charge / discharge cycles and the discharge capacity. [Figure 46] FIG. 1 shows a differential scanning calorimetry curve. [Figure 47] FIG. 1 shows the results of EDX measurement. [Figure 48] FIG. 1 shows the results of EDX measurement. [Figure 49] FIG. 1 shows the results of EDX measurement. [Figure 50] FIG. 1 shows the results of EDX measurement. [Figure 51] FIG. 1 shows the results of EDX measurement. [Figure 52] FIG. [Figure 53] FIG. 1 shows the results of XPS measurements. [Figure 54] FIG. 1 shows the results of XPS measurements. [Figure 55] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0051] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various modifications may be made to the modes and details thereof. The present invention will be easily understood by reading the following description of the embodiments. In explaining the configuration of the invention using drawings, the same thing is indicated. The same symbols are used in common between different drawings. In some cases, the same code is used and no particular symbol is assigned.

[0052] In the drawings, the size, thickness of the film (layer), or area is exaggerated for clarity. This may be the case.

[0053] The ordinal numbers such as 1st and 2nd are used for convenience and do not indicate the order of processes or stacking. It does not indicate the layer order. For example, "first" should not be replaced with "second" or "third" In addition, the ordinal numbers described in this specification and the like can be replaced with the ordinal numbers. , the ordinal numbers used to identify an aspect of the present invention may not match.

[0054] The active material refers only to the material involved in the insertion and desorption of ions, which are carriers. In the specification, etc., the term may include a layer that covers the "active material."

[0055] (Embodiment 1) In this embodiment, the "particles having lithium manganese composite oxide" according to one embodiment of the present invention will be described. An electrode having the particles will also be described.

[0056] The lithium manganese composite oxide according to one embodiment of the present invention has the composition formula Li a Mn b M c O d Expressed as Here, the element M is a metal element selected from the group consisting of lithium and manganese, It is preferable to use silicon or phosphorus for a. Also, 0≦a / (b+c)<2 and c>0 It is preferable that the ratio satisfies 0.26≦(b+c) / d<0.5. The manganese complex oxide refers to an oxide containing at least lithium and manganese, and chromium, cobalt, and magnesium. Baltic, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, At least one selected from the group consisting of gallium, copper, titanium, niobium, silicon, and phosphorus. The lithium manganese composite oxide may contain at least one element. It is preferable that the lithium manganese composite oxide has a crystal structure of the type It may have a layered rock salt type crystal structure or a spinel type crystal structure. The lithium manganese composite oxide has, for example, an average primary particle diameter of 5 nm or more and 50 μm or less. It is preferable that:

[0057] <Synthesis> Next, a method for producing "particles containing lithium manganese composite oxide" according to one embodiment of the present invention will be described. In this embodiment, first, a lithium manganese composite oxide is synthesized. Thereafter, a coating layer is formed on the lithium manganese composite oxide, and the first region, the second region, and A particle having a third region is obtained.

[0058] The raw materials for lithium manganese composite oxide are manganese compounds and lithium compounds. In addition, chromium compounds can be used together with the raw materials of manganese compounds and lithium compounds. , cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium selected from the group consisting of aluminum, gallium, copper, titanium, niobium, silicon, and phosphorus, A compound containing at least one element can be used as a raw material. Examples of manganese oxide include manganese dioxide, manganese trioxide, manganese tetraoxide, and hydrated manganese oxide. Manganese carbonate, manganese nitrate, etc. can be used. For example, lithium hydroxide, lithium carbonate, lithium nitrate, etc. can be used. .

[0059] In this embodiment, MnCO3 is used as the manganese compound and Li2C is used as the lithium compound. O3 and NiO are used as starting materials.

[0060] First, as shown in step S11 of FIG. 1, Li2CO3 and Mn are used as starting materials. CO3 and NiO are used and weighed separately.

[0061] For example, when Li2CO3, MnCO3, and NiO are used as starting materials, the weight If the molar ratio is Li2CO3:MnCO3:NiO=1:0.7:0.3, the maximum The final product, lithium manganese composite oxide, is Li2Mn 0.7 Ni 0.3 O3 In this case, the atomic ratio of the lithium manganese composite oxide is Li:( Mn + Ni) = 2:1.

[0062] In this embodiment, the atomic ratio of the lithium manganese composite oxide is Li:(Mn+Ni)= The ratio (molar ratio) of the weighed starting materials is adjusted so that it deviates from 2:1.

[0063] In this embodiment, the ratio (molar ratio) of the weights of the starting materials is Li2CO3:MnCO3:N Weigh out the components so that the ratio of iO is 0.84:0.8062:0.318.

[0064] Next, as shown in step S12 of FIG. 1, Li2CO3, MnCO3, and NiO There is no particular limitation on the method for mixing the starting materials, and a known crusher or grinder may be used. For example, a ball mill, a bead mill, a jet mill, a roller mill, etc. The crushing and pulverizing method may be either a dry method or a wet method. There is no particular limitation on the solvent that can be used, and examples thereof include water, alcohol, acetone, etc. etc. can be used.

[0065] When mixing the starting materials in a wet manner, as shown in step S13 of FIG. 1, A heating treatment is carried out to evaporate the solvent contained in the mixed starting materials. The heat treatment can be carried out at a temperature of 50°C or higher and 150°C or lower. The solvent contained in the starting material is evaporated to obtain a mixed material.

[0066] Next, as shown in step S14 of FIG. 1, the mixed raw materials are placed in a crucible and heated to 800° C. or higher for 10 The firing is carried out at a temperature of 00°C or less. The firing time is, for example, 5 hours or more and 20 hours or less. Dry air is used for firing, and the flow rate is 10 L / min. The firing atmosphere can also be air. Alternatively, an atmosphere using oxygen gas may be used. (Lithium manganese composite oxide) is formed.

[0067] As shown in Figure 2(A), the lithium ion is formed by sintering multiple primary particles synthesized by firing. Manganese composite oxide is a state in which multiple primary particles are sintered to form large secondary particles. Therefore, as shown in step S15 of FIG. 1, a lithium sintered material is prepared by sintering a plurality of primary particles. The sintered material is crushed to obtain the manganese oxide. The fired product is crushed into primary particles or into a powder close to primary particles. The crushing treatment also includes the operation of pulverizing the sintered product. The crushing process is carried out using a known crusher or grinder, similar to the method for mixing the starting materials. For example, a ball mill, a bead mill, or the like can be used. The crushing and pulverizing method may be either dry or wet. The solvent is not particularly limited, and for example, water, alcohol, acetone, etc. can be used. do.

[0068] Here, the size of particles after crushing and pulverization can be determined by, for example, measuring the specific surface area of ​​the particles. The ratio of particles containing lithium manganese composite oxide can be evaluated by measuring the ratio of particles containing lithium manganese composite oxide. By increasing the surface area, particles containing lithium manganese composite oxide are used for the positive electrode. When manufacturing a storage battery using the particles, for example, the contact area between the particles and the electrolyte can be increased. By increasing the contact area with the electrolyte, the reaction rate of the battery can be increased. The force characteristics can be improved.

[0069] By carrying out the crushing treatment, the specific surface area of ​​the particles may be increased, which is preferable. The specific surface area of ​​the particles containing manganese composite oxide is, for example, 0.1 m 2 / g or more is preferred. Furthermore, if the specific surface area of ​​the particles becomes too large, the surface of the electrode made using the particles may become too large. The amount of binder may be insufficient for the area, resulting in a decrease in strength. Increasing the binder content may decrease the electrode capacity per unit weight and volume. Therefore, the specific surface area of ​​the particles containing lithium manganese composite oxide is, for example, 1 m 2 / g More than 50m 2 / g or less is preferable, and 5m 2 / g or more 30m 2 / g or less is more preferable.

[0070] In this embodiment, the lithium manganese composite oxide in which the primary particles are sintered is crushed by the following method. This is done by a wet method using acetone in a rice mill.

[0071] When crushing is performed in a wet manner, heating is required to evaporate the solvent after crushing. The heat treatment here may be performed in the same manner as in step S13. Drying is carried out to obtain a powdery lithium manganese composite oxide.

[0072] Next, a heat treatment is performed. As shown in step S16 of FIG. 1, the crushed powder is placed in a crucible. The treated lithium manganese composite oxide is placed in the oven at 300°C or higher and 1000°C or lower, preferably Heat treatment is carried out at 600°C or higher and 900°C or lower. The heating time is, for example, 5 hours to 20 hours. The gas used is dry air, and the flow rate is 10 L / min. The heating atmosphere is air. The atmosphere may be an air atmosphere or an atmosphere using oxygen gas.

[0073] Through the above process, the composition formula Li a Mn b M c O d Lithium manganese composite oxide represented by In this embodiment, the weighed ratio (molar ratio) of the raw materials is set to L By adjusting the ratio of i2CO3:MnCO3:NiO to 0.84:0.8062:0.318, The formula is Li 1.68 Mn 0.8062 M 0.318 Lithium manganese represented by O3 A composite oxide can be formed.

[0074] In addition, the lithium manganese composite oxide after the crushing treatment shown in step S15 is The impact of the crushing process may cause crystallinity to become disordered. Therefore, the powdered lithium manganese oxide after vacuum drying may have oxygen deficiency. It is preferable to subject the calcium carbonate composite oxide to a heat treatment again.

[0075] By heat treating the crushed lithium manganese composite oxide, oxygen deficiency is repaired. At the same time, it is possible to recover the crystallinity disturbance caused by the crushing treatment. The powdered lithium manganese composite oxide after the crushing may be crushed again. In this case, the crushing process can be performed using the same method as step S15 in FIG. .

[0076] Here, the ratio of Li2CO3:MnCO3:NiO=0.84:0.8062:0.318 Using the raw material, a lithium manganese composite oxide was synthesized according to steps S11 to S16 shown in FIG. The temperature stability of the prepared sample was evaluated by differential scanning calorimetry. Figure 46 shows the differential scanning calorimetry (DSC) curve. The vertical axis shows heat flow and the horizontal axis shows temperature. As shown in Figure 6, a peak indicating an exothermic reaction was observed at 262.2°C. Therefore, the lithium manganese compound of one embodiment of the present invention was stable in DSC evaluation. It is clear that the gun oxide is stable even at high temperatures below 260°C.

[0077] The lithium manganese composite oxide shown in this embodiment has an atomic ratio of Li:(Mn+Ni) The atomic ratio is adjusted so that it deviates from Li:(Mn+Ni)=2:1. Compared to using a lithium manganese composite oxide with a ratio of 2:1 as the electrode, the voltage increases. , the discharge capacity also increases.

[0078] By the above steps, particulate lithium manganese composite oxide can be obtained. The lithium manganese composite oxide preferably has a first region and a second region. The second region is in contact with at least a portion of the surface of the first region and is located outside the first region. Here, outside refers to closer to the surface of the particle.

[0079] The first region and the second region contain lithium and oxygen. At least one of the first and second regions contains manganese. At least one of the regions has an element M. Here, the element M is lithium, manganese, or the like. Metal elements other than those mentioned above, or silicon and phosphorus are preferred, and Ni, Ga, Fe, Mo , In, Nb, Nd, Co, Sm, Mg, Al, Ti, Cu, or Zn It is more preferable that the metal element is one of silicon and phosphorus, and nickel is particularly preferable. More preferable.

[0080] <Coating layer> Next, a coating layer is provided on the obtained lithium manganese composite oxide. Since carbon has high electrical conductivity, it is preferable to use carbon-coated particles for the electrodes of storage batteries. By providing the coating layer, for example, the resistance of the electrode can be reduced. The graphene oxide may be a graphene oxide or a reduced graphene oxide.

[0081] Alternatively, the coating layer may comprise a metal compound, where the metal may be, for example, cobalt, Examples include aluminum, nickel, iron, manganese, titanium, zinc, lithium, and carbon. As an example of the metal compound, the coating layer may contain oxides or fluorides of these metals. Good too.

[0082] In this embodiment, a layer containing carbon is provided as the coating layer. Graphene has excellent electrical properties such as high electrical conductivity. It has excellent physical properties, including high tensile strength, flexibility, and mechanical strength.

[0083] In this specification, graphene refers to a single layer of graphene or a layer of graphene having 2 to 100 layers. This includes multi-layer graphene with a single-layer graphene below. Single-layer graphene is a graphene with a π bond. Graphene oxide is a sheet of carbon molecules with a single atomic layer. Graphene is a compound in which graphene oxide is oxidized. When graphene oxide is used, not all of the oxygen contained in it is released, but some of the oxygen remains in the graphene. When oxygen is present in graphene, the oxygen fraction can be determined by X-ray photoelectron spectroscopy (XP S), 2 atomic % or more and 20 atomic % or less of the entire graphene, Preferably, it is 3 atomic % or more and 15 atomic % or less.

[0084] The thickness of the carbon-containing layer is preferably 1 nm or more and 50 nm or less.

[0085] Next, a method for providing a layer containing carbon on a lithium manganese composite oxide will be described. In the embodiment, the carbon-containing layer is made of graphene oxide (Graphene Oxide Graphene (Reduced Gr; abbreviated as GO) was obtained by reducing RGO (referred to as RGO) is used.

[0086] Graphene oxide can be produced by the Hummers method, the modified Hummers method, or by black It can be prepared using various synthesis methods, such as oxidation of lead.

[0087] For example, the Hummers method involves oxidizing graphite, such as flake graphite, to form a sintered product. This is a method for forming graphite. The graphite oxide formed is Oxidation occurs in parts, resulting in the formation of functional groups such as carbonyl groups, carboxyl groups, and hydroxyl groups. The crystallinity of graphite is impaired and the distance between layers is increased. Therefore, it is possible to easily separate the layers and obtain graphene oxide by ultrasonic treatment or other methods. can.

[0088] The length of one side of graphene oxide (also called flake size) is 50 nm or more and 10 The larger the flake size, the better. This is preferable because it makes it easier to cover the surface of the lithium manganese composite oxide.

[0089] First, graphene oxide and water are placed in a kneader to prepare a dispersion solution of graphene oxide. In this case, the graphene oxide content is preferably 0.5 wt% or more and 5 wt% or less. If the amount is less than 5 wt%, it becomes difficult to cover the surface of the lithium manganese composite oxide. Furthermore, if the content exceeds 5 wt %, the electrode volume becomes bulky and the electrode weight becomes heavy.

[0090] Next, as shown in step S17 in FIG. 1, a lithium manganese composite oxide is added to the dispersion solution. Put the ingredients in and knead them firmly. Note that "kneading firmly" refers to kneading with high viscosity. This allows the agglomeration of the lithium manganese composite oxide powder to be broken down, resulting in the formation of graphene oxide. This allows the lithium manganese composite oxide to be dispersed more uniformly.

[0091] Next, the mixture of graphene oxide and lithium manganese composite oxide was placed in a bell jar under reduced pressure. After drying, the graphene oxide-coated lithium manganese was obtained by crushing it in a mortar. A composite oxide is obtained.

[0092] Next, as shown in step S18 in FIG. 1, a compound is formed on the surface of the lithium manganese composite oxide. The coated graphene oxide is then subjected to a reduction treatment. The reduction treatment of graphene oxide is carried out by heat treatment. Alternatively, the reaction may be carried out in a solvent using a reducing agent. In the method, graphene oxide is reacted with a reducing agent in a solvent.

[0093] By reacting graphene oxide with a reducing agent in a solvent, lithium manganese The graphene oxide coated on the surface of the composite oxide is reduced to form graphene. The oxygen contained in the graphene oxide is not completely released, and some of the oxygen remains in the graphene. When oxygen is contained in graphene, the oxygen ratio is measured by XPS. In this case, the content of the graphene is 2 atomic % or more and 20 atomic % or less, preferably 3 atomic % or less, of the entire graphene. The reduction treatment is carried out at a temperature between room temperature and 150°C. Preferably, the reduction treatment is carried out at a temperature of room temperature or higher and 80° C. or lower. The reduction reaction can be accelerated by this. , can be between 3 minutes and 10 hours.

[0094] Reducing agents include ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, Sodium borohydride (NaBH4), tetrabutylammonium bromide (TBAB ), lithium aluminum hydride (LiAlH4), N,N-diethylhydroxylamine For example, ascorbic acid and hydrochloric acid may be used. Quinone has a lower reducing power than hydrazine or sodium borohydride, making it safer and easier to process. This is preferable in that it is easy to use commercially.

[0095] The solvent may be a polar solvent, as long as it can dissolve the reducing agent. The material is not limited, for example, water, methanol, ethanol, acetone, tetrahydrofuran, etc. THF, dimethylformamide (DMF), 1-methyl-2-pyrrolidone ( NMP) and dimethyl sulfoxide (DMSO), ethylene glycol, diethylene glycol Licorice and glycerin can be used alone or in a mixture of two or more thereof.

[0096] The reducing solution containing a reducing agent and a solvent includes a mixture of ethanol and ascorbic acid, Alternatively, a mixture of water, ascorbic acid, and lithium hydroxide can be used. In the embodiment, when a reducing solution containing ascorbic acid, water, and lithium hydroxide is used, This article explains:

[0097] Reacting graphene oxide coated on lithium manganese composite oxide in a reducing solution Graphene oxide is protonated by ascorbic acid. Then, H2 The elimination of O reduces graphene oxide.

[0098] After the reduction treatment, the powder is collected as shown in step S19 in FIG. The reduced solution is filtered. The substance obtained here is called substance A. For filtration, suction filtration etc. is used. Alternatively, the substance A and the liquid may be separated using centrifugation.

[0099] Next, the obtained substance A is washed. For example, the washing is carried out using the solvent contained in the reducing solution. The solvent may be the same as the solvent contained in the reducing solution, or Different solvents may be used.

[0100] Next, drying is performed. This drying step is performed at a temperature of, for example, 50° C. or higher and lower than 500° C., more preferably This drying should be carried out at a temperature of 120°C to 400°C for 1 hour to 48 hours. The polar solvent and water are evaporated or removed by this drying process. The reduction of laphene can be promoted by carrying out the reaction under reduced pressure (vacuum) or in a reducing atmosphere. The drying may be carried out at atmospheric pressure or under atmospheric pressure. Air may also be used as the atmosphere during drying. Alternatively, nitrogen or other inert gases may be used.

[0101] Here, when the substance A is a particle, it is preferable that the particle forms, for example, a secondary particle. stomach.

[0102] Here, when the substance A forms secondary particles, the average particle size of the secondary particles is preferably, for example, Preferably, it is 50 μm or less, more preferably 30 μm or less, and further preferably 1 μm or more and 20 μm or less. The particle size here refers to the particle size measured using a particle size distribution analyzer, for example. When substance A forms secondary particles, the particle size may refer to the particle size of the secondary particles. The particle size can be calculated by observing the particles under a microscope, in addition to the particle size distribution meter mentioned above. The particle size can be calculated by calculating the diameter of a circle from the cross-sectional area, for example.

[0103] After washing the substance A, a solution was prepared by dispersing the substance A in a solvent, and the solution was sprayed with The substance A may be dried by spray drying. However, the particle size may change due to the formation of secondary particles, for example.

[0104] It is also preferable to further perform heat treatment after the spray drying treatment. at a temperature of 120°C or higher but lower than 500°C, more preferably 120°C or higher but lower than 400°C, for 1 hour or longer and 48 hours or longer. This heat treatment is preferably carried out for less than 1 hour. The heat treatment step can also promote the reduction of graphene oxide. The heat treatment may be carried out under reduced pressure (vacuum) or atmospheric pressure. It may also be carried out in a reducing atmosphere. The atmosphere during heating may be air, nitrogen, or other inert gas. A gas may also be used.

[0105] Through the above process, graphene oxide is reduced and formed on the surface of the lithium manganese composite oxide. Graphene can be formed.

[0106] It is not necessary to remove all of the oxygen contained in graphene oxide. If oxygen is contained in graphene, the oxygen ratio is XP When measured by S, it is 2 atomic % or more and 20 atomic % or less of the whole graphene, Preferably, it is 3 atomic % or more and 15 atomic % or less.

[0107] By performing heat treatment after reduction treatment, the graphene obtained is In some cases, the electrical conductivity of the material can be further increased.

[0108] By performing heat treatment after the reduction treatment, for example, the "lithium manganese In the "particles having a composite oxide," first to third regions may be formed. The first to third regions of the "particles containing lithium manganese composite oxide" are: It may be formed before the heat treatment, or may be formed during the heat treatment. For example, the first region formed before the coating layer is formed, after the coating layer is formed, and after the reduction treatment. The thickness, composition, and crystal structure of the third region may change during the heat treatment.

[0109] Furthermore, by carrying out heat treatment, for example, the elements contained in the binder and the lithium manganese For example, when the binder contains PVd, When F is used, the fluorine contained in PVdF and the lithium manganese composite oxide Particles of lithium, manganese, and one or more of element M, and metal fluoride may be formed.

[0110] Alternatively, a coating layer of lithium manganese composite oxide, for example, a layer containing carbon, is used here as an example. However, the element contained in the coating layer may form a bond with fluorine. When a layer containing carbon is used as the coating layer, a carbon fluoride may be formed. The particle may include a third region having a "particle having a lithium manganese composite oxide." Alternatively, the third region and a part of the first region or the second region may be included. The second region of the "particles containing lithium manganese composite oxide" is, for example, the coating layer may have a part of

[0111] By the above steps, graphene is formed on at least a part of the surface of the lithium manganese composite oxide. It is possible to form particles provided with

[0112] Graphene has excellent electrical properties, such as high electrical conductivity, and flexibility and mechanical properties. It has excellent physical properties such as high strength. Therefore, electrodes containing these particles are used in batteries. This can, for example, further improve the electrical conductivity and physical properties of the electrode.

[0113] By the above steps, particles according to one embodiment of the present invention can be obtained. The particle of one embodiment of the present invention has a first region and a second region. It is preferable that the second region has three or more regions.

[0114] One embodiment of the present invention is a particle having a lithium manganese composite oxide.

[0115] The particle having a lithium manganese composite oxide according to one embodiment of the present invention has a first region and The present invention also provides a method for manufacturing a lithium-manganese composite oxide-containing electrode comprising the steps of: The particles preferably have a third region.

[0116] The second region is in contact with at least a portion of the surface of the first region and is located outside the first region. The third region is located at the outer side of the particle. It is preferable that the first region contacts at least a part of the surface of the second region and is located outside the second region. .

[0117] In addition, when the second region has a layered region, the thickness thereof is, for example, 0.1 nm or more and 30 nm or less. It is preferably 1 nm or less, and more preferably 1 nm or more and 15 nm or less.

[0118] The first region and the second region contain lithium and oxygen. At least one of the first and second regions contains manganese. At least one of the regions has the element M.

[0119] The first region and the second region may also contain both manganese and the element M. More preferable.

[0120] The third region is a particle having a lithium manganese composite oxide according to one embodiment of the present invention. Preferably, the surface comprises:

[0121] In addition, when the third region has a layer-like region, the thickness thereof is, for example, 0.1 nm or more and 30 nm or less. Preferably, the thickness is 1 nm or less, more preferably 1 nm or more and 20 nm or less, It is more preferable that the thickness is between 10 nm and 10 nm.

[0122] In FIG. 2(A), the particle is divided into a first region 131, a second region 132, and a third region 133. and a third region 133.

[0123] As shown in FIG. 2A, the region 132 is at least partially in contact with the surface of the region 131. Moreover, at least a portion of the region 133 is in contact with the surface of the region 132 .

[0124] As shown in FIG. 2B, the region 131 has a region that is not covered by the region 132. Also, the region 132 may have an area that is not covered by the region 133. For example, the region 131 may have a region where the region 133 is adjacent to the region 131. 2 and region 133.

[0125] According to one embodiment of the present invention, a power storage device is provided using particles containing a lithium-manganese composite oxide. When fabricated, the third region acts as a catalyst for the battery reaction, e.g., charging and discharging, in addition to the first and second regions. It is preferable that it is more stable than the second region.

[0126] Here, the second region may have a different crystal structure from the first region. The region may have crystals with a different orientation than the first region.

[0127] For example, the second region has a spinel structure and the first region has a layered rock salt structure. It is preferable that

[0128] Alternatively, for example, the first region and the second region have a layered rock salt structure, and the first The first plane of the crystal in the first region and the second plane of the crystal in the second region are parallel to each other. It is preferable that:

[0129] Here, if the first plane is the {0 0 1} plane of the layered rock-salt structure, the {0 The {1 0 1} plane corresponds to the {1 0 0} plane and the {1 3 -1} plane of the crystal of the second region. It is preferable that the surface is parallel to at least one of the {-1 3 1} plane and the {-1 3 1} plane. When the first plane is the {1 0 0} plane of the layered rock-salt structure, The {0} plane is a {0 0 1} plane, a {1 3 -1} plane, or a {0 0 1} plane of the crystal of the second region. is preferably parallel to at least one of the {-1 3 1} planes. If the plane of 1 is the {1 3 -1} plane of the layered rocksalt structure, then the {1 3 -1 } plane is a {0 0 1} plane, a {1 0 0} plane, or a { It is preferable that the first surface is parallel to at least one of the {-1 3 1} planes. If the face is a {-1 3 1} face of a layered rock salt structure, then the {-1 3 1} face of a layered rock salt structure is the {0 0 1} plane, {1 0 0} plane or {1 3-1} plane.

[0130] For example, the first region and the second region have a layered rock salt structure, and the first region The first crystal orientation of the first region is parallel to the second crystal orientation of the second region. Here, it is preferable that the crystals in the first region and the crystals in the second region are The direction will be explained.

[0131] Here, the three crystal orientations, <1 0 0>, <1 1 0> and <-1 1 0>, are Let us define the first group as the first set of elements. Let us define the second group as the first set of elements. Also, <-3 2 3>, <3 1 6> and <6 -1 3> are the third group. Furthermore, <3 2 -3>, <3 -1 6> and <6 1 3> are the fourth group.

[0132] The crystals of the first region are selected from one of the first to fourth groups. The crystals in the second region have the same orientation as the crystals in the first to fourth groups in the first region. The orientation of the crystal is selected from one of the three groups other than the group from which the orientation of the crystal is selected. It has a direction.

[0133] An example of the above combination will be explained below with a specific example. ) plane and (100) plane. For the sake of specific description, we will use the symmetry of the crystal as follows. The index is written in a way that does not take into account this.

[0134] Figure 3 shows the crystal structure of Li2MnO3 as viewed from the negative direction of the b axis. The layer A-1 and the layer A-2 in the area surrounded by the dashed line A are arranged from the layer A-2 side. The view from the direction perpendicular to the layers A-1 and A-2 is shown in Figure 4(A). and layer A-2 has lithium and manganese.

[0135] In addition, the layer B-1 and the layer B-2 included in the area surrounded by the dashed line B shown in FIG. 3 are referred to as the layer B-2 side. A view from the direction perpendicular to layers B-1 and B-2 is shown in Figure 4(B).

[0136] In FIG. 4(A), lithium or manganese is oriented in the

[0110] direction or The layers are stacked with a shift in the [-100] or [1-10] direction. Similarly, in Figure 4(B), On top of the hexagonal structure formed by oxygen, lithium or manganese is arranged in the [0-11] direction or The layers are stacked with a shift in the [00-1] direction or the

[0011] direction. If manganese is replaced with lithium in the region enclosed by , the same structure as in FIG. 4(B) is obtained. In other words, although the types of metal atoms are different, the positions of the metal atoms are roughly the same. Therefore, the two structures have many things in common and are thought to have good compatibility when stacked.

[0137] Preferably, the second region has a different composition from the first region.

[0138] For example, a first region may have lithium, manganese, the element M, and oxygen, and a second region may have lithium. a first region having lithium, manganese, the element M, and oxygen; The atomic ratio of lithium, ma, and oxygen is expressed as a1:b1:c1:d1 in the second region. The atomic ratio of the elements M, M, and Oxygen is expressed as a2:b2:c2:d2. Here, d1÷(b1+c1) is preferably 2.2 or more, and more preferably 2.3 or more. It is more preferable that the ratio is 2.35 or more and 3 or less, and it is even more preferable that the ratio is 2.35 or more and 3 or less. b2+c2) is preferably less than 2.2, more preferably less than 2.1. , and more preferably 1.1 or more and 1.9 or less.

[0139] In addition, the manganese in the second region has a different valence than the manganese in the first region. The element M contained in the second region may have a valence different from that of the element M contained in the first region. It may have a number.

[0140] Here, if there is a spatial distribution in the composition of each region or the valence of elements, for example, The composition and valence of each region are evaluated, and the average value is calculated. good.

[0141] A transition layer may be provided between the second region and the first region. For example, the transition layer is a region where the composition changes continuously or stepwise. A transition layer is a region where the structure changes continuously or stepwise. This is a region where the constant changes continuously or in steps.

[0142] Alternatively, a mixed layer may be provided between the second region and the first region. For example, it refers to a layer in which two or more crystals having different crystal orientations are mixed. refers to a layer in which two or more crystals having different crystal structures are mixed. For example, this refers to a layer in which two or more crystals having different compositions are mixed.

[0143] Here, the first region preferably has a layered rock salt structure. It is preferable that the crystalline silicon has at least one of a spinel structure and a layered rock salt structure. stomach.

[0144] Here, for example, the "particles containing lithium manganese composite oxide" according to one embodiment of the present invention is used. When a storage battery or the like is manufactured using the above method, the first region to the third region are used in each step until the storage battery is manufactured. Area 3 may be formed.

[0145] For example, the first to third regions are formed before the electrode is fabricated, for example, after the particles are synthesized. Alternatively, the particles may be formed during the process of forming the electrodes. The thickness, composition, and crystal structure of the first to third regions formed later are determined by the electrode formation. The temperature may change during the process.

[0146] The first to third regions are formed by heat treatment in each step of manufacturing a storage battery or the like. It may be made.

[0147] In the manufacturing process of lithium manganese composite oxide, the primary particles shown in S15 etc. are sintered. The crushing process of the lithium manganese composite oxide is an important process that determines the characteristics of the battery. In the crushing process, the primary particles are sintered into the lithium manganese composite oxide. By applying crushing stress, powdered lithium manganese composite oxide is formed. At this time, when the lithium manganese composite oxide has a layered rock salt type crystal structure, the layers and Cleavage and splitting of primary particles in a plane parallel to or perpendicular to the layer In this specification, particles that have been cleaved and broken are referred to as particles having cleavage planes. The primary particles that have been broken are called particles with exposed cleavage planes. This also includes those that do not have it.

[0148] In addition, cleavage is not possible with lithium manganese composite oxides, which have a layered rock salt crystal structure. When particles having the above structure are used as an active material, the particles are crushed not only during the crushing process but also during the electrode manufacturing process. When pressure is applied to the electrode to form it, the pressure applied to the active material layer causes the active material to be further compressed. It may break easily.

[0149] Furthermore, when manufacturing a wound-type battery, a large stress acts on the electrodes when they are wound. Even when the electrode winding is housed in a housing, stress always acts toward the outside of the winding shaft. Therefore, there is a risk that the active material may be further cracked.

[0150] In this way, the primary particles of the lithium manganese composite oxide, which is the active material, are cleaved and broken. This can lead to a decrease in the discharge capacity of the battery and a decrease in the cycle characteristics.

[0151] Even in such a case, a layer containing carbon is formed on the cleavage plane of the lithium manganese composite oxide. The carbon-containing layer may cover the entire cleavage plane, or may cover only the cleavage plane. The cleavage plane may be entirely covered with the lithium manganese composite oxide. For example, this includes surfaces exposed by cleavage.

[0152] One embodiment of the present invention is a method for manufacturing a lithium-manganese composite oxide, in which graphene is formed so as to cover the lithium-manganese composite oxide. The graphene may be provided on the entire surface of the lithium manganese composite oxide, or on a part of the surface. Alternatively, the graphene may be provided only on the particle so as to cover the exposed cleavage plane. It is preferable that the cleavage plane of the lithium manganese composite oxide is formed at least in the following manner. It is sufficient that graphene is provided on a part of the cleavage plane. By using this active material in the electrodes, the decrease in battery voltage and discharge capacity can be suppressed. This makes it possible to improve the cycle characteristics of the battery during charging and discharging. .

[0153] Graphene has excellent physical properties such as high flexibility and mechanical strength. Therefore, by using an electrode containing this active material in a battery, the battery can be repeatedly charged and discharged, Even if the lithium manganese composite oxide expands and contracts, the volume change will not affect the lithium manganese composite. This can prevent the oxide from further cleaving and cracking.

[0154] In addition, in the electrode manufacturing process, when pressure is applied to the electrode to form it, the lithium manganese complex The mechanical strength of graphene can alleviate the pressure on the composite. This prevents the lithium manganese composite oxide from further cleaving and cracking. Cut.

[0155] Furthermore, in wound-type batteries, if a large stress is applied when the electrodes are wound, or if the electrodes When the winding is housed in a housing, if stress is constantly applied to the electrodes in the outward direction of the winding axis, However, this can prevent the lithium manganese composite oxide from further cleaving and cracking. Cut.

[0156] <Electrode configuration> Next, an electrode using particles according to one embodiment of the present invention will be described.

[0157] FIG. 5(A) is a diagram of the electrode 100 seen from above, and FIG. 5(B) is a diagram of the electrode 100 surrounded by the dashed line in FIG. 5(A). The electrode 100 has an active material layer 102 provided on a current collector 101. In FIG. 5(A), the active material layer 102 is provided on both sides of the current collector 101. However, the active material layer 102 may be provided on only one surface of the current collector 101.

[0158] The current collector 101 may be any material as long as it exhibits high electrical conductivity without causing significant chemical changes within the storage device. There are no special restrictions. For example, stainless steel, gold, platinum, zinc, iron, nickel, copper, aluminum Metals such as aluminum, titanium, tantalum, manganese, and their alloys, sintered carbon, etc. Copper or stainless steel coated with carbon, nickel, titanium, etc. In addition, the heat resistance of silicon, neodymium, scandium, molybdenum, etc. can be improved. Aluminum alloys containing elements that react with silicon can be used. Alternatively, the metal element may be formed from a metal element capable of forming a silicide by reacting with silicon. Metal elements that form silicide include zirconium, titanium, hafnium, and vanadium. Aluminum, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The current collector 101 may be in the form of a foil, a plate (sheet), a mesh, a cylinder, a coil, a punch, or the like. Various forms including expanded metal, porous and nonwoven fabrics are available. Furthermore, in order to improve the adhesion with the active material layer, the current collector 10 The current collector 101 may have a fine unevenness on its surface. It is recommended to use one with a particle size of 0 μm or less.

[0159] The active material layer 102 contains an active material. The active material is a material that is capable of inserting and extracting ions, which act as carriers. However, in this specification, in addition to the material that is originally an "active material," The active material layer also includes the agent, binder, etc.

[0160] When a negative electrode active material is used as the active material, for example, a carbon-based material, an alloy-based material, etc. is used. It is possible.

[0161] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon. carbon nanotubes, graphene, carbon black, etc. .

[0162] As graphite, mesocarbon microbeads (MCMB), coke-based artificial graphite, These include artificial graphite such as titanium-based artificial graphite, and natural graphite such as spherical natural graphite.

[0163] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), the potential is , and shows a low potential similar to that of lithium metal (0.1V to 0.3V vs. Li / L i + This allows the lithium-ion secondary battery to exhibit a high operating voltage. In addition, graphite has a relatively high capacity per unit volume, a small volume expansion, is inexpensive, and is a lithium It is preferable because it has advantages such as higher safety compared to aluminum metal.

[0164] An alloying material can be used as the negative electrode active material. A material that can undergo charge-discharge reactions by being alloyed with a metal that becomes a carrier ion For example, Ga, Si, Al, Ge, Sn, Pb, Sb, Bi, A Materials containing at least one of Zn, Cd, In, etc. can be used. Such elements have a larger capacity than carbon, and silicon in particular has a theoretical capacity of 4200mAh / g. Since the element has a high valence, the capacity of the power storage device can be increased. Examples of the oxides include SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3 Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, C Examples include oSb3, InSb, and SbSn.

[0165] Here, in order to increase the capacity of the power storage device, a material containing silicon is used as the negative electrode active material. It is particularly preferable to use, for example, silicon or SiO. Here, SiO means silicon. and oxygen, and if the atomic ratio of silicon to oxygen is silicon:oxygen=α:β, then α It is preferable that α has a value close to β. Here, having a value close to β means, for example, The absolute value of the difference is preferably 20% or less, more preferably 10% or less, relative to the value of β. That's fine.

[0166] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4 Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5 ), tungsten oxide (WO2), molybdenum oxide (MoO2), etc. can be done.

[0167] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. つ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 (900mAh / g, 1890mAh / cm 3 )of This is preferable.

[0168] When a composite nitride of lithium and transition metals is used, lithium ions are included in the negative electrode active material, As a positive electrode active material, materials that do not contain lithium ions, such as V2O5 and Cr3O8, are used. In addition, when a material containing lithium ions is used as the positive electrode active material, However, by first removing the lithium ions contained in the positive electrode active material, As the lithium-transition metal nitride, a complex nitride of lithium and a transition metal can be used.

[0169] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. For example, lithium oxides such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO) A transition metal oxide that does not undergo an alloying reaction with the metal may be used as the negative electrode active material. Further materials that can react include Fe2O3, CuO, Cu2O, RuO2, Cr2 Oxides such as O3, CoS 0.89, sulfides such as NiS and CuS, Zn3N2, Cu3N, Nitrides such as Ge3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF It also occurs with tertiary fluorides.

[0170] When a positive electrode active material is used as the active material, the positive electrode active material is a material for inserting lithium ions. For example, materials with an olivine structure, a layered rock salt structure, etc. Materials having a spinel structure, a NASICON structure, or the like can be used. Cut.

[0171] In this embodiment, particles containing lithium manganese composite oxide are used as the positive electrode active material. However, other active materials may be used. For example, LiFeO2, LiCoO2, LiNiO2, LiMn2O4, V2O5, Cr2 Compounds such as O5 and MnO2 can be used as materials.

[0172] Alternatively, lithium-containing complex phosphate (general formula LiMPO4 (M is Fe(II), Mn (II), Co(II), Ni(II), or one or more of the following can be used. Representative examples of MPO4 include LiFePO4, LiNiPO4, LiCoPO4, and LiM nPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4 , LiNi a Co b PO4, LiNi a Mn b PO4(a+b is less than 1, 0 <a<1、0 <b<1)、LiFe c Ni d Coe 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,​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (where m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc., lithium silicate compounds are exemplified.

[0174] Also, as the active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, Mn , Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) represented by the general formula of NA SICON type compounds can be used. Examples of NASICON type compounds include Fe2( MnO4)3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, As the positive electrode active material, compounds represented by the general formula Li2MPO4F, Li2MP2O7, Li5MO4 (M = Fe, M n), perovskite type fluorides such as NaF3, FeF3, T iS2, MoS2 and other metal chalcogenides (sulfides, selenides, tellurides), LiM VO4 and other materials having an inverse spinel type crystal structure, vanadium oxide systems (V2O5, V6 O 13 , LiV3O8, etc.), manganese oxides, organic sulfur compounds and other materials can be used. can be.

[0175] Note that the carrier ion is an alkali metal ion other than lithium ion, alkaline earth metal In the case of metal ions, the positive electrode active material is the lithium compound and the lithium-containing complex phosphate. In the salts and lithium-containing complex silicates, lithium is replaced by an alkali metal (e.g., sodium alkaline earth metals (e.g., calcium, strontium, barium, etc.), Compounds substituted with a carrier such as ammonium, beryllium, magnesium, etc. may also be used.

[0176] The average particle size of the positive electrode active material is preferably, for example, 5 nm or more and 50 μm or less.

[0177] The active material layer 102 may also contain a conductive additive, such as natural graphite. , artificial graphite such as mesocarbon microbeads, carbon fiber, etc. can be used. Examples of the fibers include mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers. Fibers can be used. Carbon fibers include carbon nanofibers and carbon Carbon nanotubes can be grown by vapor deposition or the like. In addition, as a conductive additive, for example, carbon black (acetylene) Carbon materials such as carbon black (AB) or graphene can be used. For example, metal powders and fibers such as copper, nickel, aluminum, silver, and gold, and conductive ceramics Materials such as acrylic resin can be used.

[0178] Flaky graphene has excellent electrical properties, including high conductivity, flexibility, and Therefore, graphene has excellent physical properties, such as mechanical strength, and is used as a conductive additive. By using such a material, the number of contact points and the contact area between active materials can be increased.

[0179] The active material layer 102 preferably contains a binder, which is a water-soluble polymer. It is more preferable that the active material layer 102 contains a plurality of types of binders. Good too.

[0180] Binders include polyvinylidene fluoride (PVdF), polystyrene, and polyacrylic. Methyl acrylate, polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl Polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide , polyimide (PI), polyvinyl chloride, polytetrafluoroethylene, polyethylene, Polypropylene, isobutylene, polyethylene terephthalate, nylon, polyacrylonitrile It is preferable to use a material such as nitrile (PAN).

[0181] Styrene-butadiene rubber (SBR), styrene-isoprene, and Styrene rubber, acrylonitrile butadiene rubber, butadiene rubber, ethylene polypropylene Rubber materials such as pyrene-diene copolymers can be used. These rubber materials are water-soluble. It is more preferable to use these rubber materials in combination with water-soluble polymers. As it is easily stretched and contracted, it is difficult to prevent the expansion and contraction of the active material during charging and discharging, and the strain caused by bending the electrode. While it is resistant to stress and can produce highly reliable electrodes, it has a hydrophobic group and is difficult to dissolve in water. In such cases, the particles are dispersed in an aqueous solution without dissolving in water. A composition containing a solvent used to form the active material layer 102 (also referred to as an electrode mixture composition) is applied. It can be difficult to increase the viscosity to a level suitable for spreading. The use of highly water-soluble polymers, such as polysaccharides, is expected to have the effect of increasing the viscosity of the solution to an appropriate degree. In addition, it can be dispersed uniformly with the rubber material, resulting in a highly uniform and good electrode, for example, Furthermore, electrodes with high uniformity in electrode resistance can be obtained.

[0182] As the water-soluble polymer, for example, polysaccharides can be used. Carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydro cellulose such as hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose; Derivatives, starch, etc. can be used.

[0183] The binders may be used alone or in combination of two or more. stomach.

[0184] <Electrode manufacturing method> Next, a method for manufacturing the electrode 100 according to one embodiment of the present invention will be described.

[0185] First, an electrode mixture composition is prepared. The electrode mixture composition is prepared by using, for example, the above-described active material. It can be produced by adding binders, conductive additives, etc. and kneading them with a solvent. The electrode mixture composition may be in the form of a slurry or a paste. For example, water or NMP (N-methyl-2-pyrrolidone) can be used. From the viewpoints of safety and cost, it is preferable to use water.

[0186] As an example, the case where the electrode 100 is a positive electrode for a storage battery will be described. The active material according to one embodiment of the present invention is used, acetylene black is used as a conductive additive, and binder An example in which PVdF is used as the binder and NMP is used as the solvent will be described.

[0187] First, the active material according to one embodiment of the present invention, acetylene black, and polyvinylidene fluoride NMP is added to the mixture until it reaches a predetermined viscosity, and the mixture is kneaded. In this step, the electrode mixture composition is formed by kneading and mixing the polar solvent. The electrode mixture composition may be in the form of a slurry or a paste. It is also possible.

[0188] Through the above steps, an electrode mixture composition in which the active material, conductive additive, and binder are uniformly dispersed is obtained. can be formed.

[0189] Here, an undercoat may be formed on the current collector. This refers to a coating layer that reduces contact resistance and improves adhesion between the current collector and the active material layer. Examples of the substrate include a carbon layer, a metal layer, a layer containing carbon and a polymer, and a layer containing metal and a polymer. By forming an undercoat on the current collector, It is possible to reduce the contact resistance between the current collector and the active material layer that will be formed later. The undercoat can improve adhesion to the active material layer. When graphene oxide is used, it is necessary to use a material that does not dissolve in the reducing solution during the graphene oxide reduction process. It is preferable that:

[0190] The undercoat may be, for example, a dispersion solution of graphite or acetylene black. Alternatively, a mixture of the aqueous solution with a polymer can be used. For example, a mixture of graphite and a polyaniline can be used. Mixtures with sodium acrylate (PAA) and mixtures of AB and PVdF are used. The weight ratio of graphite to PAA can be set to be in the range of graphite:PAA=95:5 to 50:5. The blending ratio of AB to PVdF ranges from 70:30 to 50:50. The range may be set as follows.

[0191] If there are no problems with the adhesion between the active material layer and the current collector, the electrode strength, or the contact resistance, The coating does not necessarily have to be formed on the current collector.

[0192] Next, the slurry is applied to one or both surfaces of the current collector by a coating method such as a doctor blade method. It will be established according to the following.

[0193] Next, the slurry provided on the current collector is dried by a method such as ventilation drying or reduced pressure (vacuum) drying. The active material layer is formed by drying the substrate at a temperature of, for example, 50°C or higher and 180°C or lower. This step is preferably carried out using wind. This step evaporates the polar solvent contained in the active material layer. The atmosphere is not particularly limited.

[0194] Here, this active material layer is pressed by a compression method such as a roll press method or a flat plate press method. The density of the active material layer may be increased by pressing the active material layer. By applying heat below 0°C, preferably below 120°C, the undercoat and the active material layer The binder (e.g., PVdF) contained in the electrode is softened to a degree that does not change the properties of the electrode. This can further improve the adhesion between the current collector and the active material layer.

[0195] Next, the active material layer is subjected to a heat treatment to evaporate the solvent. This heat treatment step is preferably carried out in a reducing atmosphere. , more preferably 120°C or higher and 500°C or lower, and even more preferably 200°C or higher and 400°C or lower. The heat treatment is preferably carried out at a temperature of 1 hour to 48 hours. The polar solvent and water present in the solution are evaporated or removed.

[0196] Here, for example, the "particles containing lithium manganese composite oxide" according to one embodiment of the present invention is used. When an electrode is produced using the lithium manganese composite oxide and a storage battery is produced using the electrode, The first region to the third region of the "particle having a lithium manganese composite oxide" The particles are formed during the manufacturing process of the "particles having the structure" and the manufacturing process of the storage battery. Good too.

[0197] <Heat treatment> Here, by carrying out the heat treatment, for example, the "lithium manganese composite" of one embodiment of the present invention can be obtained. In the "particles having an oxide," first to third regions may be formed.

[0198] The first to third regions of the "particles containing lithium manganese composite oxide" are The regions may be formed prior to electrode fabrication, for example, after particle synthesis. Alternatively, the first region may be formed after the synthesis of the particles. The thickness, composition, and crystal structure of the third region may be changed during the process of forming the electrode. In addition, the first to third regions are formed by heat treatment in each step of manufacturing a storage battery or the like. It may be made.

[0199] Furthermore, by carrying out heat treatment, for example, the elements contained in the binder and the lithium manganese As an example, the binder may react with the elements contained in the particles containing the binder composite oxide. PVdF is a polymer compound containing fluorine. By using a fluorine-containing polymer compound as a binder, the material that constitutes the electrode can be The bond between fluorine and elements contained in other materials, such as active materials, conductive additives, current collectors, etc., is formed. Here, the term "having a bond" means that the bond can be formed by analyzing using, for example, XPS. Alternatively, having a bond refers to, for example, a material having the bond. For example, metal fluorides are materials that have such bonds. Examples of metal fluorides include the lithium manganese composite oxide of one embodiment of the present invention. Form metal fluorides with lithium, manganese, and element M, which are metals that fluorides have. Or, it may form a bond with the metal used in the current collector.

[0200] Alternatively, a coating layer of lithium manganese composite oxide, for example, a layer containing carbon, is used here as an example. However, the element contained in the coating layer may form a bond with fluorine. When a layer containing carbon is used as the coating layer, a carbon fluoride may be formed. The particle may include a third region having a "particle having a lithium manganese composite oxide." Alternatively, the third region and a part of the first region or the second region may be included. The second region of the "particles containing lithium manganese composite oxide" is, for example, the coating layer may have a part of

[0201] By forming such a bond, for example, the strength of the electrode can be increased. Alternatively, by forming the bond in advance, it is possible to manufacture a storage battery, for example. After this, irreversible reactions may be suppressed when charging and discharging the battery. This may cause a change in the volume of the active material, which may lead to a decrease in the strength of the electrode. When the adhesion decreases, for example, the adhesion between the active materials or between the active materials and the conductive additive decreases. This can reduce the conductive path of the electrodes, resulting in a reduction in capacitance. By forming the electrode, the strength of the electrode is improved and the electrode's resistance to volume changes is improved. There are cases where this happens.

[0202] The preferred temperature for the heat treatment to form the bond is, for example, 120°C or higher, more preferably is preferably 160°C or higher, more preferably 200°C or higher, and even more preferably 250°C or higher.

[0203] The atmosphere for the heat treatment may be oxygen, air, nitrogen, rare gas, or the like. The heat treatment may be carried out under atmospheric pressure or under reduced pressure. By using a gas having the above properties, the materials constituting the electrodes, such as lithium manganese composite oxide, The reaction between the particles containing the oxide and the binder may be accelerated. The reaction between the binder and the lithium manganese complex is promoted, for example. The bond between the elements of the particles containing the composite oxide can be observed by analysis such as XPS. In addition, by using inert gases such as nitrogen and rare gases, each of the electrodes can be It may be possible to suppress the deterioration of materials, such as current collectors. By carrying out this treatment, it is possible to prevent deterioration of the materials that make up the electrode, such as the current collector. It may be possible.

[0204] If the heat treatment temperature is too high, the materials constituting the electrode may decompose. For example, particles containing lithium manganese composite oxide undergo a decomposition reaction and are released into the battery. Therefore, the heat treatment temperature is set to 600°C. Preferably, the temperature is 500°C or lower, more preferably 500°C or lower, and even more preferably 400°C or lower.

[0205] <Press> Furthermore, the current collector on which the active material layer is formed may be pressed. The adhesion between the active material layer and the current collector can be improved. When pressing, heat should be applied at 90°C or higher and 180°C or lower, preferably 120°C or lower. By adding the binder (e.g., PVdF) contained in the undercoat and active material layer, By softening the electrode to a degree that does not change the properties of the electrode, the adhesion between the current collector and the active material layer can be improved. can be further increased.

[0206] Finally, the current collector and active material layer are punched out to a predetermined size to produce an electrode. do.

[0207] Note that one embodiment of the present invention has been described in this embodiment. However, the present invention is not limited to these embodiments. That is, various inventive aspects are described in this and other embodiments. Therefore, one embodiment of the present invention is not limited to a specific embodiment. As an example, an example in which the present invention is applied to a lithium ion secondary battery has been shown. In some cases, or depending on the circumstances, one aspect of the present invention is to Secondary batteries, lead-acid batteries, lithium-ion polymer secondary batteries, nickel-metal hydride batteries, nickel Nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver-oxide-zinc batteries battery, solid-state battery, air battery, primary battery, capacitor, or lithium ion capacitor, For example, depending on the circumstances, the present invention may be applied to This embodiment does not necessarily have to be applied to a lithium ion secondary battery. In the above, examples in which the active material has graphene or graphene oxide have been shown. One aspect of the present invention is not limited to this. In one aspect, graphene or graphene oxide is a very high capacitance capacitor It can be used as an electrode for supercapacitors (electric double layer capacitors) and as an oxygen reduction electrode. It can be used as an electrode catalyst, a material for dispersion water with lower friction than lubricating oil, and in display devices and large-screen displays. It can be used as a transparent electrode for solar cells, a gas barrier material, or for its mechanical strength. It can be used as a lightweight polymer material with high thermal conductivity, or as a material for removing uranium and plutonium contained in radioactive contaminated water. It can be used as a material for highly sensitive nanosensors to detect uranium, or to remove radioactive materials. It may also be used as a material for

[0208] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0209] (Embodiment 2) In this embodiment, an example of a power storage device using an electrode which is one embodiment of the present invention will be described.

[0210] In this specification and the like, the term "power storage device" refers to elements and devices in general that have a power storage function. For example, storage batteries such as lithium-ion secondary batteries, lithium-ion capacitors, and Includes electric double layer capacitors.

[0211] <Thin storage battery> FIG. 6 shows a thin storage battery as an example of a power storage device. If the structure has such a configuration, when the device is mounted in an electronic device having at least a part with flexibility, This allows the storage battery to bend in accordance with the deformation of the electronic device.

[0212] FIG. 6 shows an external view of a thin storage battery 500. Also, FIGS. 7(A) and 7(B) show 6 shows the A1-A2 cross section and the B1-B2 cross section indicated by the dashed dotted line. , a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, and a negative electrode current collector 504 and a negative electrode 506 having a negative electrode active material layer 505, a separator 507, and an electrolyte solution 508. , and an exterior body 509. A positive electrode 503 and a negative electrode 506 are provided in the exterior body 509. A separator 507 is placed between the two. The inside of the exterior body 509 is filled with an electrolyte 508. It has been done.

[0213] At least one of the positive electrode 503 and the negative electrode 506 is an electrode according to one embodiment of the present invention. In addition, the electrode according to one embodiment of the present invention may be used for both the positive electrode 503 and the negative electrode 506. good.

[0214] First, the structure of the positive electrode 503 will be described. Here, the electrode 100 shown in the second embodiment is used as the positive electrode 503. Here is an example of its use.

[0215] The solvent of the electrolytic solution 508 is preferably an aprotic organic solvent, for example, ethylene carbonate. Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate, Chloride Ethylene carbonate, vinylene carbonate (VC), γ-butyrolactone, γ-valerate Lactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-diol Dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, di Ethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of oran, sulfolane, sultone, etc., or any combination of two or more of these and ratios.

[0216] In addition, by using a polymer material that gels as a solvent for the electrolyte, it is possible to prevent leakage, etc. Safety is improved. In addition, it is possible to make the secondary battery thinner and lighter. Representative examples of such materials include silicone gel, acrylic gel, acrylonitrile gel, and poly Ethylene oxide gel, polypropylene oxide gel, fluorine polymer gel etc.

[0217] In addition, a flame-retardant and non-volatile ionic liquid (room-temperature molten salt) is used as the solvent for the electrolyte. By using one or more, the internal temperature of the storage device can be prevented from rising due to an internal short circuit or overcharging. Even if the battery is damaged, it can prevent the battery from exploding or catching fire. The electrolyte solution is made of tetravalent cations and anions. ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations The following aromatic cations are also used as anions in electrolytes: monovalent amide-based Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkanes sulfonic acid anion, tetrafluoroborate, perfluoroalkylborate, hexafluoromethyl Examples of the fluoroalkyl phosphate include trifluorophosphate and perfluoroalkyl phosphate.

[0218] In addition, when lithium ions are used as a carrier for the electrolyte dissolved in the solvent, In this case, for example, LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, L iSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C 2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO 2), one or more lithium salts such as LiN(C2F5SO2)2 can be used in any combination and ratio.

[0219] In addition, the electrolyte used in the electricity storage device is free from granular waste and elements other than the constituent elements of the electrolyte (hereinafter referred to as It is preferable to use a highly purified electrolyte solution with a low content of impurities. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less. More preferably, it is set to 0.01% or less.

[0220] In addition, the electrolyte contains vinylene carbonate (VC), propane sultone (PS), and tert -butylbenzene (TBB), fluoroethylene carbonate (FEC), LiBOB, etc. Any additive may be added. The concentration of the additive may be, for example, 0.1 weight percent based on the total solvent. It is sufficient to set the content to between 10% and 5% by weight.

[0221] Alternatively, a gel electrolyte may be used in which a polymer is swollen with an electrolytic solution. Examples of the gel electrolyte include a polymeric support containing the above-mentioned electrolyte. Examples include:

[0222] Examples of the host polymer are described below. Examples of the host polymer include polyethylene. Polymers with polyalkylene oxide structure such as PEO, PVdF, and polyacrylonitrile, and copolymers containing these can be used. For example, PVdF-HF, a copolymer of PVdF and hexafluoropropylene (HFP), It is possible to use P. The polymer formed may also have a porous shape.

[0223] In addition, instead of the electrolytic solution, a solid electrolyte containing an inorganic material such as a sulfide or oxide, It is possible to use a solid electrolyte containing a polymer material such as PEO (polyethylene oxide). When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire battery can be solidified, there is no risk of leakage, dramatically improving safety.

[0224] The separator 507 may be made of, for example, paper, nonwoven fabric, glass fiber, ceramics, or Nylon (polyamide), Vinylon (polyvinyl alcohol fiber), polyester, It is recommended to use synthetic fibers such as acrylic, polyolefin, and polyurethane. This can be done.

[0225] The separator 507 is processed into a bag shape and encases either the positive electrode 503 or the negative electrode 506. For example, as shown in FIG. 8(A), the positive electrode 503 is sandwiched between the positive electrode 503 and the positive electrode 504. The separator 507 is folded in half as shown in FIG. 1, and the sealing portion 51 is formed outside the area overlapping with the positive electrode 503. By sealing with 4, the positive electrode 503 can be reliably supported within the separator 507. Then, as shown in FIG. 8(B), the positive electrode 503 and the negative electrode 505 wrapped in the separator 507 are 06 are alternately stacked and placed inside an exterior body 509 to form a thin storage battery 500. It is good to form.

[0226] Here, the positive electrode active material has the lithium manganese composite oxide shown in embodiment 1. The electrode described in Embodiment 1 was used as a positive electrode 503, and silicon dioxide was used as a negative electrode active material. An example in which an active material having carbon is used will be described.

[0227] Active materials containing silicon, such as silicon and SiO, have active material weight and active material volume. This allows for a large capacity per unit weight and volume of the battery. do.

[0228] In addition to the insertion and desorption reactions of carrier ions, the following reactions occur during the charging and discharging of the battery: The decomposition reaction of the electrolyte may occur. This decomposition reaction occurs at both the positive and negative electrodes. In particular, in the negative electrode, the electrolyte may not be able to tolerate the low potential of the battery reaction. In many cases, the decomposition reaction is irreversible. The occurrence of reversible reactions can reduce the charge / discharge efficiency of the energy storage device, which can lead to a decrease in capacity. There is a match.

[0229] In such a case, the negative electrode 506 or the positive electrode 503, the counter electrode, and the electrolyte solution used in the storage battery A battery is prepared in which the above-mentioned steps are previously provided, and an irreversible reaction is caused to occur in advance, and then the battery is The negative electrode 506 or the positive electrode 503 is taken out from the battery, and a storage battery is fabricated. This is preferable because it can suppress the decrease in the capacity of the storage battery due to the For example, a material having carrier ions or a material having carrier ions may be used. Compounds having carrier ions can be used. For example, lithium may be mentioned. In addition, examples of compounds having carrier ions include: The materials listed as the positive electrode active material and the negative electrode active material in the first embodiment can be used.

[0230] Next, we will explain the aging process after the storage battery is manufactured. It is preferable to carry out aging. An example of the aging conditions is explained below. To avoid this, charge at a rate of 0.001C or more and 0.2C or less. If the electrolyte decomposes and generates gas, If gas accumulates in the cell, areas will be created where the electrolyte cannot come into contact with the electrode surface. In other words, the effective reaction area of ​​the electrode decreases, which corresponds to an increase in the effective current density. Furthermore, particles containing the lithium-manganese composite oxide of one embodiment of the present invention can be used as a positive electrode active material. When the positive electrode active material has a high reaction potential, , the voltage of the storage battery can be increased, and the energy density of the storage battery can be increased. preferable.

[0231] However, there are cases where the electrolyte does not have resistance to such a high reaction potential. For example, the electrolyte may decompose on the surface of the positive electrode, generating gas. In this case, it is preferable to degas the mixture.

[0232] In addition, if the current density becomes too high, a voltage drop occurs depending on the resistance of the electrode, and this causes leakage to the graphite. At the same time as lithium insertion occurs, lithium deposition on the graphite surface also occurs. Deposition can lead to a decrease in capacity. For example, after lithium is deposited, a film or the like forms on the surface. If the capacity is increased, the lithium deposited on the surface cannot be re-eluted, and the lithium that does not contribute to the capacity is lost. In addition, if the deposited lithium physically collapses and loses its electrical connection with the electrode, However, lithium that does not contribute to the capacity is generated. It is preferable to degas before reaching the lithium potential.

[0233] Also, aging may be performed while pressing. For example, when a thin storage battery is manufactured, After that, charging and discharging may be performed while pressing using a press machine.

[0234] The lithium manganese composite oxide of one embodiment of the present invention is preferred because it has a large discharge capacity. Furthermore, the lithium manganese composite oxide of one embodiment of the present invention has a high potential for battery reaction. , has a high energy density and is preferred.

[0235] On the other hand, when an active material with a high battery reaction potential is used as the positive electrode of a storage battery, the electrolyte When the electrolyte decomposes, gas is generated near the surface of the positive electrode. This may occur.

[0236] By performing aging while pressing, the gas generated is released This may be preferable as it can be expelled to areas other than the area, for example, the periphery of the storage battery.

[0237] Here, for example, pressing may be performed while heating. Although pressing may be performed, it is more preferable to perform aging while pressing.

[0238] After degassing, the temperature is set higher than room temperature, preferably 30°C or higher and 60°C or lower. More preferably, the temperature is 35°C or higher and 50°C or lower, and the charging time is, for example, 1 hour or higher and 100 hours or lower. During the initial charging, the electrolyte decomposed on the surface is transferred to the surface of the graphite. Therefore, for example, by keeping the temperature higher than room temperature after degassing, However, it is also conceivable that the formed coating may become dense.

[0239] As shown in FIG. 9(A), the positive electrode current collector of the positive electrode 503 is welded by ultrasonic welding or the like. The negative electrode 506 is welded to the positive electrode lead electrode 510 in the welding region 512. It is welded to the negative electrode lead electrode 511. FIG. 9(B) shows an example in which the current collector is welded to the lead electrode. As an example, a case where the positive electrode current collector is welded to the positive electrode lead electrode 510 is shown. The battery 500 has a curved portion 513 shown in FIG. 9(B), so that the battery 500 can be easily removed from the outside after fabrication. This can alleviate stress caused by the application of force from the outside, thereby improving the reliability of the storage battery 500. This can be done.

[0240] In the thin storage battery 500 shown in FIGS. 6 and 7, the positive electrode lead electrode 510 is The positive electrode current collector 501 of the negative electrode 506 is connected to the negative electrode lead electrode 511. 504, respectively, to form a positive lead electrode 510 and a negative lead electrode 511. The positive electrode current collector 501 and the positive electrode current collector 502 serve as terminals for electrical contact with the outside. In this case, the positive electrode current collector 504 can be used as the positive electrode current collector 505 without using a lead electrode. The current collector 501 and the negative electrode current collector 504 are arranged so that a part of them is exposed to the outside from the exterior body 509. It may be placed.

[0241] In addition, in FIG. 6, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side. However, as shown in FIG. 10, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are connected to different sides. In this way, the storage battery according to one aspect of the present invention allows the lead electrodes to be freely arranged. Therefore, the degree of design freedom is high. In addition, the productivity of a product using the storage battery of one embodiment of the present invention can be improved. can be increased.

[0242] In the thin storage battery 500, the exterior body 509 is made of, for example, polyethylene or polypropylene. Aluminum is coated on a film made of a material such as polyethylene terephthalate, polycarbonate, ionomer, or polyamide. A thin metal film made of highly flexible material such as aluminum, stainless steel, copper, or nickel is applied to the surface of the thin metal film. The outer surface of the exterior body is covered with an insulating synthetic resin film such as polyamide resin or polyester resin. A film having a three-layer structure can be used.

[0243] In addition, in FIG. 6, as an example, the number of pairs of opposing positive and negative electrodes is set to five. The number of electrode pairs is not limited to five, and may be more or less. In this case, a storage battery with a larger capacity can be obtained. In addition, the battery can be made thinner and more flexible.

[0244] In the above configuration, the exterior body 509 of the secondary battery has a curvature radius of 30 mm or more, preferably a curvature radius of 10 mm or more. The film that is the exterior of the secondary battery can be deformed within a radius of 10 mm or more. In the case of a secondary battery with a laminated structure consisting of one or two sheets, the cross section of the curved battery The surface structure is sandwiched between two curves of the film exterior.

[0245] The radius of curvature of a surface will be explained with reference to FIG. 11. In FIG. 11(A), the curved surface 170 On a plane 1701 cutting through 0, a part of a curve 1702 included in a surface 1700 is cut into a circle. Approximate the arc, and let the radius of the circle be the radius of curvature 1703 and the center of the circle be the center of curvature 1704. FIG. 11(B) shows a top view of the curved surface 1700. FIG. 11(C) shows the curved surface 1700 on a plane 1701. The cross section of 1700 is shown. When cutting a curved surface with a plane, the angle of the plane to the curved surface is The radius of curvature of the curve that appears in the cross section will differ depending on the cutting position and the thickness. The smallest radius of curvature is taken as the radius of curvature of the surface.

[0246] The secondary battery is curved, sandwiching electrodes, electrolyte, etc., 1805 between two films as the exterior body. In this case, 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 ( When a secondary battery is bent to make its cross section arc-shaped, the center of curvature is 180°. The surface of the film is subjected to compressive stress, and the surface of the film far from the center of curvature 180° is subjected to tension. The pattern formed by the recesses or protrusions on the surface of the exterior body is subjected to tension stress (Fig. 12(B)). When formed, even if compressive stress or tensile stress is applied, the effect of strain is not Therefore, the secondary battery can be mounted on the exterior body near the center of curvature. The radius of curvature can be deformed within a range of 30 mm or more, preferably 10 mm or more.

[0247] The cross-sectional shape of the secondary battery is not limited to a simple arc shape, and may be a shape having a partial arc. For example, the shape shown in FIG. 12(C), a wave shape (FIG. 12(D)), an S-shape, etc. When the curved surface of the secondary battery has a shape with multiple centers of curvature, Among the radii of curvature at each of the centers of curvature, the surface with the smallest radius of curvature is 2 The radius of curvature of the outer casing closest to the center of curvature of the outer casing is 10 mm or more, preferably 30 mm The secondary battery can be deformed within the above range.

[0248] <Coin-type battery> Next, as an example of the power storage device, an example of a coin-type storage battery will be described with reference to FIG. 13. Figure 13(A) is an external view of a coin-type (single-layer flat) storage battery, and Figure 13(B) is , and its cross-sectional view.

[0249] The coin-type storage 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. 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305. The positive electrode active material layer 306 may be formed by the following method. .

[0250] The negative electrode 307 is composed of a negative electrode current collector 308 and a negative electrode active material provided in contact with the negative electrode current collector. The negative electrode active material layer 309 is formed by the layer 309. For the negative electrode active material layer 309, refer to the description of the negative electrode active material layer 505. For the separator 310, the description of the separator 507 may be referred to. For the solution, refer to the description of the electrolyte 508.

[0251] The positive electrode 304 and the negative electrode 307 used in the coin-type storage battery 300 are each an active material. The barrier layer need only be formed on one side.

[0252] The positive electrode can 301 and the negative electrode can 302 are made of nickel or aluminum, which is corrosion-resistant to the electrolyte. Metals such as aluminum and titanium, or alloys of these and other metals (e.g., stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is the positive electrode 304, and the negative electrode can 302 is the negative electrode. 307 and electrically connected to each other.

[0253] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the negative electrode 307, the positive electrode 304, and the separator 310 are then immersed in an electrolyte. As shown in Fig. 1B, the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, and negative electrode 307 are placed in the same container. The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are secured together with a gasket 303. The coin-type storage battery 300 is manufactured by crimping the components together.

[0254] <Cylindrical storage battery> Next, a cylindrical storage battery will be shown as an example of a power storage device. The cylindrical storage battery 600 has a positive electrode on the top surface as shown in FIG. It has a cap (battery lid) 601 and a battery can (external can) 602 on the side and bottom. The positive electrode cap and the battery can (external can) 602 are connected by a gasket (insulating packing) 606. It is insulated by 10.

[0255] Fig. 14(B) is a schematic diagram showing the cross section of a cylindrical storage battery. Inside the can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are placed with a separator 605 sandwiched between them. The battery element is wound around a center pin (not shown). 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 corrosion-resistant to the electrolyte, or Alloys of these and other metals (e.g., stainless steel) can be used. In addition, it is preferable to coat the electrode with nickel, aluminum, etc. to prevent corrosion by the electrolyte. 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. The inside of the battery can 602 is filled with a non-aqueous electrolyte (not shown). A coin-type storage battery or the like can be used.

[0256] The positive electrode 604 and the negative electrode 606 are fabricated in the same manner as the positive and negative electrodes of the thin battery described above. In addition, since the positive and negative electrodes used in cylindrical storage batteries are wound, both sides of the current collector It is preferable to form an active material on the surface of the positive electrode 604. 3 is connected to the negative electrode 606, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. The negative electrode terminal 603 and the negative electrode terminal 607 can both be made of a metal material such as aluminum. The positive terminal 603 is connected to the safety valve mechanism 612, and the negative terminal 607 is connected to the bottom of the battery can 602. The safety valve mechanism 612 is made of a PTC (Positive Tempered The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via the The safety valve mechanism 612 is connected to the positive electrode when the internal pressure of the battery exceeds a predetermined threshold. This cuts off the electrical connection between the electrode cap 601 and the positive electrode 604. The element 611 is a thermosensitive resistor whose resistance increases when the temperature rises. It limits the amount of current to prevent abnormal heat generation. The PTC element is made of barium titanate ( BaTiO3-based semiconductor ceramics, etc. can be used.

[0257] When winding electrodes in a cylindrical storage battery as shown in Figure 14, large amounts of In addition, when the electrode winding body is housed in a housing, the electrode always has a winding shaft. Even if a large stress acts on the electrode, the active material This can prevent the material from cleaving.

[0258] In this embodiment, the storage battery is a coin type, a cylindrical type, and a thin type. However, other storage batteries of various shapes such as sealed storage batteries and square storage batteries can also be used. In addition, a structure in which a positive electrode, a negative electrode, and a separator are stacked in multiple layers ... and a structure in which a positive electrode, a negative electrode, and a separator are stacked in multiple layers are stacked in multiple layers are stacked in multiple layers. For example, other examples of storage batteries are shown in Figs. vinegar.

[0259] <Example of storage battery configuration> 15 and 16 show examples of the configuration of a thin storage battery. The battery 3 includes a negative electrode 994 , a positive electrode 995 , and a separator 996 .

[0260] The wound body 993 is made up of a negative electrode 994 and a positive electrode 995 stacked together with a separator 996 sandwiched therebetween. The laminated sheet is then wound up. This wound body 993 is then placed in a square sealed container or the like. A square secondary battery is produced by covering the battery with a material such as aluminum.

[0261] The number of layers of the negative electrode 994, the positive electrode 995, and the separator 996 may be as many as necessary. The negative electrode 994 is connected to the lead electrode 997 and the lead electrode 998. The positive electrode 995 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 998. The positive electrode 997 is connected to a positive electrode current collector (not shown) via the other of the electrode 997 and the lead electrode 998. .

[0262] The storage battery 990 shown in FIGS. 15(B) and 15(C) is made of a film 981 that serves as an exterior body. and a film 982 having a recess are bonded together by thermocompression or the like to form a space. The winding body 993 includes a lead electrode 997 and a lead wire 998. The film 981 and the film 982 having the recesses are electrolytically connected to each other. It is impregnated with liquid.

[0263] The film 981 and the film 982 having the recesses are made of a metal material such as aluminum. The film 981 and the film 982 having the recesses can be made of a metal or resin material. If a resin material is used as the material for the recess, when an external force is applied, the film 981 and the recess The film 982 having the above structure can be deformed to produce a flexible storage battery. can be done.

[0264] In addition, although Fig. 15(B) and Fig. 15(C) show examples using two films, A space is formed by folding one film, and the above-mentioned wound body 9 is inserted into the space. 93 may also be accommodated.

[0265] In addition, by using resin materials for the exterior body of a thin storage battery or a sealed container, flexibility can be improved. However, it is possible to manufacture a power storage device having a resin material for the outer casing or the sealing container. In this case, the part that is connected to the outside must be made of conductive material.

[0266] For example, another example of a thin storage battery having flexibility is shown in FIG. 16. The wound body 9 in FIG. 16(A) 93 is the same as that shown in FIG. 15(A), so detailed description will be omitted. .

[0267] The storage battery 990 shown in FIG. 16(B) and FIG. 16(C) has the above-described structure inside an exterior body 991. The winding body 993 includes a lead electrode 997 and a lead The electrode 998 is provided, and the inside of the exterior bodies 991 and 992 is impregnated with an electrolyte. The outer casing 992 can be made of a metal material such as aluminum or a resin material. If a resin material is used as the material for 991 and 992, the outer casing 9 91, 992 can be deformed to produce a thin flexible storage battery. do.

[0268] An electrode including an active material according to one embodiment of the present invention can be used in a flexible thin storage battery. This allows the thin battery to remain active even if stress is applied to the electrodes by repeatedly bending the battery. This can prevent the material from being cleaved.

[0269] As a result, an active material having at least a part of the cleavage plane covered with graphene can be used for an electrode. This makes it possible to suppress a decrease in the battery voltage and a decrease in the discharge capacity. The cycle characteristics of the battery during charging and discharging can be improved.

[0270] <Example of energy storage system structure> An example of the structure of the power storage system will be described with reference to FIGS. 17 to 19. The power system refers to, for example, a device equipped with a power storage device.

[0271] 17(A) and 17(B) are diagrams showing the external appearance of the power storage system. The system includes a circuit board 900 and a battery 913. The battery 913 is labeled with a label 91. 17(B), the power storage system has a terminal 951 and , terminal 952, antenna 914, and antenna 915.

[0272] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 95. 1, terminal 952, antenna 914, antenna 915, and circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is connected to a control signal input terminal, a power supply terminal, and the like. It may also be a terminal.

[0273] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. Also, planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, induction Alternatively, an antenna such as an electric antenna may be used. 5 may be a flat conductor. This flat conductor functions as one of the conductors for electric field coupling. In other words, one of the two conductors of the capacitor is The antenna 914 or the antenna 915 may be activated. Not only that, but it is also possible to exchange power using an electric field.

[0274] The line width of antenna 914 is preferably larger than the line width of antenna 915. This allows the amount of power received by the antenna 914 to be increased.

[0275] The storage system includes a layer 9 between the antenna 914 and the antenna 915 and the storage battery 913. The layer 916 has a function capable of shielding the electromagnetic field generated by the battery 913, for example. The layer 916 may be made of, for example, a magnetic material.

[0276] The structure of the power storage system is not limited to the structure shown in FIG.

[0277] For example, as shown in FIGS. 18(A-1) and 18(A-2), In the storage battery 913 shown in FIG. 17(B), an antenna is provided on each of a pair of opposing surfaces. FIG. 18(A-1) is an external view seen from one side of the pair of surfaces. 8(A-2) is an external view seen from the other side of the pair of surfaces. 17(A) and 17(B) are the same as those in the power storage system shown in FIG. The explanation of the storage system shown in 7(B) can be used as appropriate.

[0278] As shown in FIG. 18(A-1), a layer 916 is sandwiched between one of the two surfaces of a storage battery 913. As shown in FIG. 18(A-2), an antenna 914 is provided on both sides of the storage battery 913. An antenna 915 is provided on the opposite side with a layer 917 sandwiched therebetween. The layer 917 is connected to, for example, a storage battery 913. The layer 917 has a function of blocking the electromagnetic field generated by the magnetic field. You can be there.

[0279] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It can be heard.

[0280] Alternatively, as shown in Figs. 18(B-1) and 18(B-2), In the storage battery 913 shown in FIG. 17(B), a separate antenna is attached to each of a pair of opposing surfaces. Fig. 18(B-1) is an external view of the pair of surfaces as seen from one side. FIG. 18(B-2) is an external view seen from the other side of the pair of surfaces. The same parts as those in the storage system shown in Fig. 17(A) and Fig. 17(B) are The description of the power storage system shown in FIG. 17B can be used as appropriate.

[0281] As shown in FIG. 18(B-1), a layer 916 is sandwiched between one of the two surfaces of the storage battery 913. An antenna 914 and an antenna 915 are provided, and as shown in FIG. 18(A-2), An antenna 918 is provided on the other of the two surfaces of the antenna 913, sandwiching a layer 917 therebetween. The antenna 91 has a function of, for example, performing data communication with an external device. 8, for example, an antenna having a shape applicable to antenna 914 and antenna 915 is applied. As a communication method between the power storage system and other devices via the antenna 918, applies a response method such as NFC that can be used between the energy storage system and other devices. It is possible.

[0282] Alternatively, as shown in FIG. 19(A), the storage battery 91 shown in FIG. 17(A) and FIG. 17(B) A display device 920 may be provided on the power supply 13. The display device 920 is connected to the power supply 13 via a terminal 919. The label 910 is electrically connected to the display device 920. It should be noted that the same parts as those in the power storage system shown in Fig. 17(A) and Fig. 17(B) may be used. For this purpose, the description of the power storage system shown in FIGS. 17(A) and 17(B) can be used as appropriate.

[0283] The display device 920 displays, for example, an image indicating whether charging is in progress or not, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display, an electronic For example, an electroluminescence (EL) display device can be used. By using the polarizer, the power consumption of the display device 920 can be reduced.

[0284] Alternatively, as shown in FIG. 19(B), the storage battery 91 shown in FIG. 17(A) and FIG. 17(B) A sensor 921 may be provided on the terminal 911 via a terminal 922. The same parts as the power storage systems shown in Figs. 17(A) and 17(B) are used. For details, the explanation of the power storage system shown in Fig. 17(A) and Fig. 17(B) can be used as appropriate. Cut.

[0285] The sensor 921 may be, for example, a sensor for detecting force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, etc. Distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation Use of devices that include the function of measuring line, flow rate, humidity, gradient, vibration, smell, or infrared rays By providing the sensor 921, for example, the environment in which the power storage system is placed can be The data (such as temperature) indicating the temperature may be detected and stored in the memory of the circuit 912. .

[0286] The battery and the power storage system described in this embodiment include an electrode according to one embodiment of the present invention. Therefore, the capacity of the storage battery and the power storage system can be increased. It is possible to increase the energy density, improve reliability, and extend the life. It can be made easier.

[0287] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0288] (Embodiment 3) In this embodiment, an example in which a flexible storage battery is mounted on an electronic device will be described.

[0289] An example in which the flexible storage battery described in Embodiment 2 is mounted in an electronic device is shown in FIG. As an example of an electronic device that uses a flexible power storage device, a television set is (also called television or television receiver), monitors for computers, digital digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, (also known as mobile telephone devices), portable game machines, personal digital assistants, audio playback devices, pachinko machines, etc. Examples include large game consoles.

[0290] In addition, the flexible energy storage device can be attached to the interior or exterior walls of houses or buildings, or to automobiles. It can also be incorporated into curved surfaces of the interior or exterior of a vehicle.

[0291] FIG. 20A shows an example of a mobile phone. The mobile phone 7400 includes a housing 740 1, in addition to a display unit 7402, operation buttons 7403, an external connection port 7404, The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. It has an electrical device 7407.

[0292] FIG. 20B shows the mobile phone 7400 in a bent state. When the 00 is deformed by an external force and the whole is curved, the storage battery installed inside The power storage device 7407 is also bent. At this time, the bent state of the power storage device 7407 is shown in FIG. The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a state in which the resistor 7408 is electrically connected to the current collector 7409. It has a gate electrode 7408.

[0293] FIG. 20(D) shows an example of a bangle-type display device. The portable display device 7100 is , a housing 7101, a display portion 7102, operation buttons 7103, and a power storage device 7104. FIG. 20E shows the bent state of the power storage device 7104. When the device is bent and worn on the user's arm, the housing may deform and cause damage to part or all of the power storage device 7104. The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed as the radius of curvature is called the curvature, and the reciprocal of the radius of curvature is called the curvature. A part of the main surface of the housing or the power storage device 7104 within the range of 40 mm to 150 mm in diameter Or the entire surface of the power storage device 7104 changes. High reliability can be maintained if the distance is within the range of 0 mm or less.

[0294] FIG. 20F shows an example of a wristwatch-type portable information terminal. The watch includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, and an operation button 7 205, an input / output terminal 7206, etc.

[0295] The portable information terminal 7200 is capable of performing functions such as mobile phone calls, e-mails, document browsing and creation, music playback, internet connection, and so on. It can run various applications such as internet communication and computer games. Cut.

[0296] The display surface of the display unit 7202 is curved, and the display is performed along the curved display surface. The display portion 7202 is provided with a touch sensor, and the screen can be touched with a finger or a stylus. For example, the icon 7 displayed on the display unit 7202 can be operated by touching the You can launch the application by touching 207.

[0297] The operation button 7205 is used to set the time, turn the power on and off, and turn wireless communication on and off. It has various functions such as auto-start, silent mode activation and deactivation, power saving mode activation and deactivation, etc. For example, an operating system built into the mobile information terminal 7200 can be The system also allows the functions of the operation buttons 7205 to be freely set.

[0298] In addition, the mobile information terminal 7200 is capable of performing standardized short-range wireless communication. For example, by communicating with a wireless headset, hands-free You can also make calls.

[0299] The portable information terminal 7200 also has an input / output terminal 7206, and can be connected to other information terminals via a connector. Data can be exchanged directly through the input / output terminal 7206. The charging operation can be performed by wireless power supply without going through the input / output terminal 7206. You may go.

[0300] The display portion 7202 of the portable information terminal 7200 includes a storage battery provided with the electrode member of one embodiment of the present invention. For example, the power storage device 7104 shown in FIG. It can be installed in a curved position inside or bendable inside the band 7203. can.

[0301] FIG. 20G shows an example of a wristband-type display device. The display device 7300 has a display unit 7304 and includes the power storage device of one embodiment of the present invention. The display portion 7304 may be provided with a touch sensor, and may function as a portable information terminal. It is also possible to do so.

[0302] The display surface of the display unit 7304 is curved, and images are displayed along the curved display surface. The display device 7300 can also communicate with the display device 7300 by short-distance wireless communication according to a communication standard. You can change the situation.

[0303] The display device 7300 is also equipped with an input / output terminal, and can be directly connected to other information terminals via a connector. It is possible to exchange data and also charge via the input / output terminal. The charging operation may be performed by wireless power supply without using the input / output terminals.

[0304] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0305] (Fourth embodiment) In this embodiment, an example of an electronic device in which a power storage device can be mounted will be described.

[0306] 21(A) and 21(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 21(A) and 21(B) includes a housing 9630a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, a display part 9 631a and a display unit 9631b, a display mode changeover switch 96 26, power switch 9627, power saving mode switch 9625, fastener 9629 , and an operation switch 9628. FIG. 21(A) shows the tablet terminal 9600 when opened. 21(B) shows the tablet terminal 9600 in a closed state.

[0307] The tablet terminal 9600 also includes a housing 9630a and a housing 9630b. The power storage unit 9635 is connected to the housing 9630a through a movable part 9640. It is provided across the body 9630b.

[0308] A part of the display portion 9631a can be used as a touch panel area 9632a. By touching the operation keys 9638, data can be input. In 31a, for example, half of the area has a display function only, and the other half Although the display area 96 has a touch panel function, the display area 96 is not limited to this configuration. The entire area of ​​the display unit 9 may have a touch panel function. The entire surface of 631a is displayed as a keyboard button to serve as a touch panel, and the display part 9631b is displayed. It can be used as a display screen.

[0309] In addition, in the display unit 9631b, as in the display unit 9631a, The area can be used as a touch panel area 9632b. Touch the area where the display switch button 9639 is displayed with your finger or a stylus. This allows keyboard buttons to be displayed on the display portion 9631b.

[0310] In addition, the touch panel area 9632a and the touch panel area 9632b are simultaneously You can also use touch input.

[0311] A display mode changeover switch 9626 changes the display orientation, such as portrait or landscape. You can switch between black and white and color display. The switch 9625 is a device that detects the use of a light sensor built into the tablet terminal 9600. The display brightness can be optimized according to the amount of external light at the time. In addition to optical sensors, other sensors such as gyros and acceleration sensors that detect tilt are also used. An ejection device may be built in.

[0312] FIG. 21A shows an example in which the display area of ​​the display portion 9631b is the same as that of the display portion 9631a. However, there is no particular limitation, and one size may be different from the other size. The display quality may also differ. For example, one display panel may be able to display a higher resolution image than the other. It may also be used as a rule.

[0313] FIG. 21(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630 and a solar cell 9631. 633, and a charge / discharge control circuit 9634 including a DC / DC converter 9636. The power storage unit of one embodiment of the present invention is used as the power storage unit 9635.

[0314] In addition, the tablet terminal 9600 can be folded in half, so when not in use, the case 9630a and The housing 9630b can be folded so that the housing 9630b overlaps the housing 9630a. , the display units 9631a and 9631b can be protected. Furthermore, the power storage unit 9635 using the power storage unit of one embodiment of the present invention can have improved durability. It has flexibility and the charge / discharge capacity is not easily reduced even when repeatedly bent and stretched. It can provide excellent tablet devices.

[0315] In addition, the tablet terminals shown in Figures 21(A) and 21(B) are also available in various other formats. Functions that display important information (still images, videos, text images, etc.), calendars, dates, or times The function to display the information on the display unit, and the function to touch input or edit the information displayed on the display unit. It has functions such as inputting characters, controlling processes using various software (programs), etc. It is possible.

[0316] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel. The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The power storage unit 9635 can be efficiently charged by providing the power storage unit 9635 on one or both sides of the housing 9630. It is to be noted that a lithium ion battery may be used as the power storage unit 9635. This has the advantage of enabling miniaturization.

[0317] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. A block diagram is shown in FIG. 21(C). In FIG. 21(C), a solar cell 9633, a power storage unit 96 35, DC-DC converter 9636, converter 9637, switches SW1 to SW3, The display unit 9631 is shown, along with a power storage unit 9635, a DC-DC converter 9636, and a The inverter 9637 and the switches SW1 to SW3 are connected to the charge / discharge control circuit 9 shown in FIG. This corresponds to 634.

[0318] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted into a voltage to charge the storage battery 9635. The converter 9636 increases or decreases the voltage. When power is used from the battery 9633, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying in 1, turn SW1 off and SW2 on to turn on the power storage unit 9635. It is sufficient to configure the device so that charging is performed.

[0319] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Storage by other power generation means such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the power supply 9635 may be configured to transmit and receive power wirelessly (contactlessly). It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. You may do so.

[0320] Another example of electronic equipment is shown in Fig. 22. In Fig. 22, a display device 8000 is a display device according to the present invention. 8 is an example of an electronic device including a power storage device 8004 of one embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker, and The power storage device 8004 of one embodiment of the present invention includes: The display device 8000 is provided inside a housing 8001. The display device 8000 is supplied with power from a commercial power source. The power can be received or stored in the power storage device 8004 can be used. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention can be used. The display device 8000 can be used by using the power storage device 8004 as an uninterruptible power supply. become.

[0321] The display unit 8002 is a display device having a light emitting element such as a liquid crystal display device or an organic EL element in each pixel. Optical devices, electrophoretic displays, DMD (Digital Micromirror Devices) ice), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0322] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. This includes all display devices for displaying information, such as:

[0323] In FIG. 22, a stationary lighting device 8100 includes a power storage device 8 according to one embodiment of the present invention. 8103. Specifically, the lighting device 8100 includes a housing 8101, The light source 8102, the power storage device 8103, and the like are included. In FIG. 101 and a light source 8102 are installed inside a ceiling 8104. Although shown in the figure, the power storage device 8103 may be provided inside the housing 8101. The device 8100 can receive power from a commercial power source or can store power in a power storage device 8103. The stored power can also be used. Therefore, in the event of a power outage, the power supply from the commercial power source can be reduced. Even when power cannot be received, the power storage device 8103 of one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0324] In addition, FIG. 22 illustrates a lighting device 8100 of a fixed type provided on a ceiling 8104. However, in the power storage device of one embodiment of the present invention, the side wall 8105, the floor 8106, and the like are not included in the ceiling 8104. It can be used for a fixed lighting device provided in a window 8107 or a desk. It can also be used in upper lighting devices.

[0325] The light source 8102 can be an artificial light source that artificially obtains light using electricity. Specifically, this applies to incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting devices such as LEDs and organic EL elements. An example of the artificial light source is a light element.

[0326] In FIG. 22, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electronic device including a power storage device 8203 of one embodiment of the present invention. The indoor unit 8200 includes a housing 8201, an air outlet 8202, a power storage device 8203, and the like. In the example shown, the power storage device 8203 is provided in the indoor unit 8200. The electric device 8203 may be provided in the outdoor unit 8204. The power storage device 8203 may be provided in both the outdoor units 8204. The power supply can be supplied from a commercial power source or stored in the power storage device 8203. In particular, both the indoor unit 8200 and the outdoor unit 8204 are provided with a power storage device 8 If 203 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the power storage device 8203 of one embodiment of the present invention as an uninterruptible power supply, Conditioner can be used.

[0327] In addition, Figure 22 shows a separate type air conditioner consisting of an indoor unit and an outdoor unit. However, it is an integrated air conditioner that has the functions of both an indoor unit and an outdoor unit in a single housing. The power storage device of one embodiment of the present invention can also be used for the conditioner.

[0328] In FIG. 22, an electric refrigerator-freezer 8300 includes a power storage device 8304 according to one embodiment of the present invention. Specifically, an electric refrigerator-freezer 8300 includes a housing 8301, The refrigerator door 8302, the freezer door 8303, the power storage device 8304, and the like are included. A power storage device 8304 is provided inside the housing 8301. The power supply can be supplied from a commercial power source, or the power stored in the power storage device 8304 can be used. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. Even in this case, by using the power storage device 8304 of one embodiment of the present invention as an uninterruptible power supply, 8300 refrigerators and freezers will be available for use.

[0329] Among the above-mentioned electronic devices, high-frequency heating devices such as microwave ovens and electric rice cookers The sub-devices require high power for a short period of time, so the power that cannot be supplied by the commercial power supply is supplemented. By using a power storage device according to one embodiment of the present invention as an auxiliary power source for This can prevent the commercial power breaker from tripping when using the

[0330] In addition, during times when electronic devices are not in use, the total amount of power that can be supplied by commercial power suppliers is also During the time period when the ratio of the amount of electricity actually used (called the electricity usage rate) is low, By storing power in the electrical equipment, it is possible to prevent the power usage rate from increasing outside the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low, the refrigerator compartment door 83 02, during the night when the freezer door 8303 is not opened or closed, power is supplied to the power storage device 8304. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 open and close. By using the power storage device 8304 as an auxiliary power source during the daytime, The rate can be kept low.

[0331] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0332] (Embodiment 5) In this embodiment, an example in which a power storage device is mounted on a vehicle will be described.

[0333] In addition, when a storage device is installed in a vehicle, it can be used as a hybrid vehicle (HEV) or electric vehicle (EV). or next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). It can be realized.

[0334] 23A and 23B illustrate examples of vehicles using one embodiment of the present invention. The 8400 is an electric vehicle that uses an electric motor as a power source for travel. It is possible to select and use an electric motor or an engine as a power source for driving. A hybrid vehicle. By using one aspect of the present invention, a vehicle with a long cruising range can be realized. The automobile 8400 also has a power storage device. The power storage device is an electric motor. It not only drives the 8406 but also the headlight 8401 and room light (not shown). The light emitting device can be supplied with power.

[0335] In addition, the power storage device may be used for displaying the speedometer, tachometer, etc. of the automobile 8400. The power storage device can supply power to the navigation system of the automobile 8400. The power supply can be used to power semiconductor devices such as gating systems.

[0336] The automobile 8500 shown in FIG. 23B is a power storage device that is plugged in. It can be charged by receiving power from an external charging facility using a method such as contactless power supply. FIG. 23(B) shows a diagram of a charging device 8021 mounted on a ground and a charging system 8022 mounted on a vehicle 8500. The power storage device 8024 is shown being charged via a cable 8022. For charging methods and connector specifications, please refer to the specifications of CHAdeMO (registered trademark) and Combo. The charging device 8021 may be a charging station installed in a commercial facility. For example, plug-in technology can be used to The power storage device 8024 mounted on the automobile 8500 can be charged by the power supply. Charging is performed by converting AC power to DC power via a converter such as an AC / DC converter. It is possible to do so.

[0337] Although not shown, a power receiving device is mounted on the vehicle, and power is supplied contactlessly from a power transmitting 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. The vehicle may transmit and receive power between them using the same method. A solar cell may be provided in the vehicle so that the power storage device can be charged when the vehicle is stopped or running. To supply power in the above, an electromagnetic induction method or a magnetic field resonance method can be used.

[0338] 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 size and weight of the power storage device itself can be reduced. This contributes to reducing the vehicle's weight, thereby improving the vehicle's cruising range. The onboard power storage device can also be used as a power supply source for vehicles. This can avoid using commercial power during peak hours.

[0339] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0340] (Embodiment 6) Batteries that can be used in combination with battery cells containing the materials described in the above embodiments A control unit (Battery Management Unit: BMU) and the battery For transistors suitable for the circuits that make up the pond control unit, see Figures 24 to 30. In this embodiment, the power supply of a power storage device having battery cells connected in series will be described. The pond control unit will now be described.

[0341] When multiple battery cells connected in series are repeatedly charged and discharged, In this case, variations occur in the charge / discharge characteristics, and the capacity (output voltage) of each battery cell differs. In a series-connected battery cell, the total discharge capacity is proportional to the capacity of the battery cell with the smallest capacity. If there is a difference in the capacity of each battery cell, the overall capacity during discharge will be smaller. In addition, if charging is performed based on the battery cell with the smallest capacity, there is a risk of insufficient charging. If charging is performed based on the battery cell with the largest capacity, there is a risk of overcharging.

[0342] Therefore, the battery control unit of the power storage device having battery cells connected in series It has the function of equalizing the capacity variations between battery cells, which can cause short circuits and overcharging. The circuit configuration to equalize the capacitance variation between the capacitors can be a resistor type, a capacitor type, or an inverter type. There are other methods such as inductor type, but here we use a transistor with a small off-current to reduce capacitance variations. An example of a circuit configuration that can align the above will be described below.

[0343] As a transistor with a low off-state current, a transistor having an oxide semiconductor in a channel formation region is An OS transistor with a small off-state current is preferred. By using it in the circuit configuration of the device's battery control unit, the amount of charge leaking from the battery is reduced, It is possible to suppress the decrease in capacity over time.

[0344] The oxide semiconductor used in the channel formation region is In-M-Zn oxide (M is Ga, Sn , Y, Zr, La, Ce, or Nd) is used. In the target, the atomic ratio of the metal elements is In:M:Zn=x1:y1:z1. and 、 x1 / y1 is 1 / 3 or more and 6 or less, and further 1 or more and 6 or less, and z1 / y1 is It is preferable that z1 / y1 is 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. When the content is 6 or less, a CAAC-OS film is easily formed as the oxide semiconductor film. .

[0345] Here, the CAAC-OS film will be described.

[0346] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts aligned along the c-axis. .

[0347] Transmission Electron Microscope (TEM) A combined analysis image of the bright-field image and diffraction pattern of the CAAC-OS film was obtained using a microscope. (also called high-resolution TEM images) On the other hand, high-resolution TEM images also clearly show the boundaries between crystals, i.e., grain boundaries. Therefore, the CAAC-OS film is It can be said that the decrease in electron mobility caused by the grain boundaries is unlikely to occur.

[0348] When a high-resolution TEM image of the cross section of the CAAC-OS film was observed from a direction approximately parallel to the sample surface, It can be seen that the metal atoms are arranged in layers in the crystal part. The CAAC-OS film is formed on a surface (also called a surface on which the film is formed) or on the upper surface. The CAAC-OS film has a shape similar to that of the crystalline silicon film, and is arranged parallel to the surface on which the CAAC-OS film is formed or the upper surface thereof.

[0349] On the other hand, a high-resolution TEM image of the plane of the CAAC-OS film was observed from a direction almost perpendicular to the sample surface. They then confirmed that the metal atoms in the crystals were arranged in triangular or hexagonal shapes. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

[0350] X-ray diffraction (XRD) of the CAAC-OS film When structural analysis is performed using this device, for example, CAAC-OS with InGaZnO4 crystals can be seen. In the out-of-plane analysis of the film, the diffraction angle (2θ) peaks around 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis faces the surface on which the film is formed or the upper surface. It can be seen that it is oriented in a substantially vertical direction.

[0351] In addition, the out-of-plane structure of the CAAC-OS film with InGaZnO4 crystals In the analysis by the NMR method, in addition to the peak at 2θ near 31°, a peak also appeared at 2θ near 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have crystalline structure. It is preferable that the peak is exhibited at 2θ of about 36° and that the peak is not exhibited at 2θ of about 36°.

[0352] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. The oxide semiconductor film is made of an element other than the main component, such as silicon or a transition metal element. The elements such as ZnO, which have stronger bonding strength with oxygen than the metal elements constituting the oxide semiconductor film, By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, and the crystallinity is reduced. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide are Because the diameter (or molecular radius) is large, when the molecule is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement of the oxide semiconductor film, which may result in a decrease in crystallinity. The pure material may act as a carrier trap or a carrier generation source.

[0353] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in semiconductor films can act as carrier traps and trap hydrogen. This can become a carrier generation source.

[0354] The low impurity concentration and low defect level density (low oxygen vacancies) are called high-purity intrinsic or The term "high-purity intrinsic" refers to a substantially high-purity intrinsic oxide semiconductor. The film has a small number of carrier generation sources, so the carrier density can be reduced. The transistor including the oxide semiconductor film has electrical characteristics in which the threshold voltage is negative. (also called normally-on) is rare. An oxide semiconductor film with intrinsic purity has few carrier traps. Transistors using conductor films have little fluctuation in electrical characteristics and are highly reliable. Note that it takes time for the charges trapped in the carrier traps in the oxide semiconductor film to be released. The time it takes for the impurity concentration to reach the target is long, and it may behave as if it were a fixed charge. A transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. This may be the case.

[0355] In addition, the electrical characteristics of transistors using CAAC-OS films are improved by irradiation with visible light or ultraviolet light. There is little gender variation.

[0356] Note that an OS transistor is a transistor having silicon in a channel formation region (Si Since the band gap is larger than that of semiconductors (transistors), dielectric breakdown occurs less when high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated. The circuit configuration of the battery control unit applied to such a battery cell in the power storage device includes the following: It is suitable to use the OS transistor described above.

[0357] An example of a block diagram of a power storage device is shown in Fig. 24. The power storage device BT00 shown in Fig. 24 includes: A terminal pair BT01, a terminal pair BT02, a switching control circuit BT03, and a switching circuit BT 04, a switching circuit BT05, a transformer control circuit BT06, and a transformer circuit BT07, and a battery unit BT08 including a plurality of battery cells BT09 connected to the battery unit BT08.

[0358] In addition, in the power storage device BT00 of FIG. 24, the terminal pair BT01 and the terminal pair BT02 are A switching control circuit BT03, a switching circuit BT04, a switching circuit BT05, and a transformer control circuit The part consisting of the control circuit BT06 and the transformer circuit BT07 is called the battery control unit. You can do it.

[0359] The switching control circuit BT03 controls the operation of the switching circuits BT04 and BT05. Specifically, the switching control circuit BT03 controls the voltage measured for each battery cell BT09. Based on the voltage, the battery cells to be discharged (discharge battery cell group) and the battery cells to be charged (charge Determine the battery cell group.

[0360] Furthermore, the switching control circuit BT03 controls the determined discharge battery cell group and charge battery cell group. The control signal S1 and the control signal S2 are output based on the group of rules. This control signal S1 is output to the circuit BT04. The control signal S2 is a signal that controls the switching circuit BT04 to connect the This control signal S2 is output to the switching circuit BT05. This signal controls the switching circuit BT05 so as to connect the BT05 to the group of conductors.

[0361] The switching control circuit BT03 includes a switching circuit BT04, a switching circuit BT05, And considering the configuration of the transformer circuit BT07, between the terminal pair BT01 and the discharge battery cell group, or Between the terminal pair BT02 and the charging battery cell group, the control is performed so that terminals of the same polarity are connected. The control signal S1 and the control signal S2 are generated.

[0362] The operation of the switching control circuit BT03 will now be described in detail.

[0363] First, the switching control circuit BT03 measures the voltage of each of the multiple battery cells BT09. Then, the switching control circuit BT03 selects, for example, the battery cell BT09 having a voltage equal to or higher than a predetermined threshold. A high-voltage battery cell (high-voltage cell), a battery cell with a voltage below a predetermined threshold BT09 is considered a low-voltage It is determined to be a battery cell (low voltage cell).

[0364] It should be noted that various methods can be used to determine whether a cell is a high-voltage cell or a low-voltage cell. For example, the switching control circuit BT03 selects the most The voltage of each battery cell BT09 is used as the reference voltage. 09 may determine whether it is a high-voltage cell or a low-voltage cell. In this case, the switching control circuit BT0 3 determines whether the voltage of each battery cell BT09 is equal to or greater than a predetermined ratio of the reference voltage. By doing so, it is possible to determine whether each battery cell BT09 is a high-voltage cell or a low-voltage cell. Then, based on the result of this determination, the switching control circuit BT03 switches between the discharge battery cell group and the charge battery cell group. The battery cell group is determined.

[0365] In addition, among the multiple battery cells BT09, high voltage cells and low voltage cells are mixed in various states. For example, the switching control circuit BT03 can The part with the largest number of high-voltage cells connected in series is the discharge battery cell group. The switching control circuit BT03 charges the part with the most low-voltage cells connected in series. The switching control circuit BT03 detects whether a battery is close to being overcharged or overdischarged. The cell BT09 is preferentially selected as a discharge battery cell group or a charge battery cell group. Good too.

[0366] An example of the operation of the switching control circuit BT03 in this embodiment will now be described with reference to FIG. FIG. 25 is a diagram for explaining an example of the operation of the switching control circuit BT03. For convenience of explanation, FIG. 25 shows an example in which four battery cells BT09 are connected in series. explain.

[0367] First, in the example of FIG. 25(A), the voltages of the battery cells a to d are voltages Va to Vd. This shows the case where the relationship Va=Vb=Vc>Vd is satisfied. In other words, three consecutive high The high-voltage cells a to c and one low-voltage cell d are connected in series. The control circuit BT03 determines three consecutive high-voltage cells a to c as a discharge battery cell group. The switching control circuit BT03 also determines the low voltage cell d as the charging battery cell group. do.

[0368] Next, the example in FIG. 25(B) shows a case where the relationship is Vc>Va=Vb>>Vd. That is, two consecutive low voltage cells a and b, one high voltage cell c, and one over-discharged cell The nearby low-voltage cell d is connected in series. In this case, the switching control circuit BT03 , the high-voltage cell c is determined as the discharge battery cell group. Since the low voltage cell d is close to over-discharge, it is not the two consecutive low voltage cells a and b that are the low voltage cells. The voltage cell d is determined as the charging battery cell group with priority.

[0369] Finally, the example in FIG. 25(C) shows a case where the relationship Va>Vb=Vc=Vd holds. That is, one high-voltage cell a and three consecutive low-voltage cells b to d are connected in series. In this case, the switching control circuit BT03 selects the high voltage cell a as the discharge battery cell group. The switching control circuit BT03 also determines whether three consecutive low-voltage cells b to d are charged. The battery cell group is determined as follows:

[0370] The switching control circuit BT03 determines the results as shown in the examples of FIGS. 25(A) to 25(C). Based on the result, information indicating the discharge battery cell group to which the switching circuit BT04 is connected is set. The control signal S1 and information indicating the charging battery cell group to which the switching circuit BT05 is connected are The set control signal S2 is sent to the switching circuit BT04 and the switching circuit BT05. Output each one.

[0371] The above is a detailed explanation of the operation of the switching control circuit BT03.

[0372] The switching circuit BT04 responds to the control signal S1 output from the switching control circuit BT03. Therefore, the connection destination of the terminal pair BT01 is determined by the switching control circuit BT03. Set to a group of cells.

[0373] The terminal pair BT01 is composed of a pair of terminals A1 and A2. 4, either one of the terminals A1 and A2 is connected to the most upstream (highest) of the discharge battery cell group. The positive terminal of the battery cell BT09 located on the positive side of the discharge battery cell group is connected to the positive terminal of the battery cell BT09 located on the positive side of the discharge battery cell group. By connecting it to the negative terminal of the battery cell BT09 located at the most downstream (low potential side), The connection destination of the child pair BT01 is set. The switching circuit BT04 is set to the control signal S1. The position of the discharged battery cell group can be recognized using the obtained information.

[0374] The switching circuit BT05 responds to the control signal S2 output from the switching control circuit BT03. Therefore, the connection destination of the terminal pair BT02 is changed to the rechargeable battery determined by the switching control circuit BT03. Set to a group of cells.

[0375] The terminal pair BT02 is composed of a pair of terminals B1 and B2. 5, either one of the terminals B1 and B2 is connected to the most upstream (highest) of the charging battery cell group. The positive terminal of the battery cell BT09 located on the positive side of the battery cell group is connected to the positive terminal of the battery cell BT09 located on the positive side of the battery group. By connecting it to the negative terminal of the battery cell BT09 located at the most downstream (low potential side), The connection destination of the slave pair BT02 is set. The switching circuit BT05 is set to the control signal S2. The position of the rechargeable battery cell group can be recognized using the obtained information.

[0376] 26 and 27 are circuit diagrams showing examples of the configuration of the switching circuits BT04 and BT05. Shown in Figure 27.

[0377] In FIG. 26, the switching circuit BT04 includes a plurality of transistors BT10 and a bus BT11. The bus BT11 is connected to the terminal A1. 12 is connected to the terminal A2. The sources or drains of the plurality of transistors BT10 One of the two is alternately connected to the bus BT11 and the other to the bus BT12. In addition, the other of the sources or drains of the plurality of transistors BT10 is connected to two adjacent It is connected between the battery cell BT09.

[0378] Among the multiple transistors BT10, the transistor BT10 located at the most upstream The other of the source and drain is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery module BT08. The most downstream of the plurality of transistors BT10 is connected to the terminals. The other of the source and drain of the transistor BT10 is located at the most downstream of the battery section BT08. The negative terminal of the battery cell BT09 is connected to the negative terminal of the battery cell BT09.

[0379] The switching circuit BT04 supplies a control signal S1 to the gates of the plurality of transistors BT10. In response to the bus BT11, one of the plurality of transistors BT10 is connected to the bus BT11. One of the plurality of transistors BT10 connected to BT12 is in a conductive state. By doing so, the discharge battery cell group and the terminal pair BT01 are connected. The positive terminal of the battery cell BT09, which is located most upstream in the cell group, is connected to the terminal A1 of the terminal pair or A2. Also, the battery located most downstream in the discharge battery cell group. The negative terminal of cell BT09 is connected to the other of the terminals A1 and A2 of the terminal pair, i.e., the positive terminal The terminal that is not connected to the other terminal is connected to the other terminal.

[0380] It is preferable to use an OS transistor for the transistor BT10. Since the off-state current of the discharged battery cell is small, the amount of charge leaking from the battery cells that do not belong to the discharged battery cell group is small. This reduces the capacitance loss over time. Dielectric breakdown is unlikely to occur when high voltage is applied. Therefore, the output voltage of the discharge battery cell group is large. Even if the voltage is high, the transistor BT10 is in a non-conducting state. The pair BT01 can be insulated.

[0381] In addition, in FIG. 26, the switching circuit BT05 includes a plurality of transistors BT13 and a current control The buses BT15 and BT16 are connected to the control switch BT14 and the bus BT15. T16 is disposed between the plurality of transistors BT13 and the current control switch BT14. The sources or drains of the plurality of transistors BT13 are alternately connected. The plurality of transistors BT13 are connected to buses BT15 and BT16. The other of the source and drain of each battery cell is connected between two adjacent battery cells BT09. It is being done.

[0382] Among the plurality of transistors BT13, the transistor BT13 located at the most upstream The other of the source and drain is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery module BT08. The most downstream of the plurality of transistors BT13 is connected to the terminals. The other of the source and drain of the transistor BT13 is located at the most downstream of the battery section BT08. The negative terminal of the battery cell BT09 is connected to the negative terminal of the battery cell BT09.

[0383] The transistor BT13 is an OS transistor, similar to the transistor BT10. Since the OS transistor has a small off-state current, it is preferable that the OS transistor does not belong to the rechargeable battery cell group. This reduces the amount of charge leaking from the battery cells and prevents the capacity from decreasing over time. In addition, OS transistors are less likely to experience dielectric breakdown when high voltages are applied. , transistor B, which is in a non-conducting state even if the voltage for charging the charging battery cell group is large. The battery cell BT09 connected to T13 can be insulated from the terminal pair BT02. .

[0384] The current control switch BT14 includes a switch pair BT17 and a switch pair BT18. One end of the switch pair BT17 is connected to the terminal B1. The other end is branched by two switches, one of which is connected to bus BT15 and the other The switch pair BT18 is connected to the bus BT16. One end of the switch pair BT18 is connected to the terminal B2. The other end of the switch pair BT18 is branched into two switches. One switch is connected to bus BT15 and the other switch is connected to bus BT16. do.

[0385] The switches included in the switch pair BT17 and the switch pair BT18 are transistors BT1 Similarly to transistors BT10 and BT13, it is preferable to use OS transistors.

[0386] The switching circuit BT05 switches the transistor BT13 and the current control By controlling the combination of on / off states of the control switch BT14, the charging battery cell Connect the group to terminal pair BT02.

[0387] As an example, the switching circuit BT05 connects the charging battery cell group and the terminal pair BT Connect to 02.

[0388] The switching circuit BT05 supplies a control signal S2 to the gates of the plurality of transistors BT13. Depending on the charging status, the positive terminal of the battery cell BT09 located most upstream in the charging battery cell group is connected. The switching circuit BT05 turns on the transistor BT13. In response to a control signal S2 applied to the gate of a number of transistors BT13, The transistor BT1 connected to the negative terminal of the battery cell BT09 located most downstream 3 is put into a conductive state.

[0389] The polarity of the voltage applied to terminal pair BT02 is the same as that of the discharge battery cell connected to terminal pair BT01. The number of cells may vary depending on the configuration of the battery cell group and the transformer circuit BT07. To allow current to flow in the same direction, the terminals of the same polarity must be connected between the terminal pair BT02 and the charging battery cells. Therefore, the current control switch BT14 is controlled by the control signal S2. , switch pair BT17 and switch pair B depending on the polarity of the voltage applied to terminal pair BT02. It is controlled to switch the connection destination of T18 respectively.

[0390] For example, a voltage is applied to terminal pair BT02 such that terminal B1 is positive and terminal B2 is negative. In this case, the most downstream battery cell BT0 of the battery module BT08 If 9 is a charging battery cell group, the switch pair BT17 is connected to the battery by the control signal S2. The switch pair BT17 is controlled to be connected to the positive terminal of the cell BT09. The switch connected to the bus BT16 is turned on, and the bus BT On the other hand, the switch pair BT18 is in the OFF state when the control signal S 2, the negative terminal of the battery cell BT09 is controlled to be connected to the negative terminal of the battery cell BT09. The switch connected to the bus BT15 of the switch pair BT18 is turned on, and The switch connected to the bus BT16 of BT18 is turned off. Between the pair BT02 and the charging battery cell group, terminals with the same polarity are connected. The direction of the current flowing from the terminal pair BT02 is controlled so that it is in the direction that charges the battery cell group. To be controlled.

[0391] In addition, the current control switch BT14 is connected to the switching circuit B instead of the switching circuit BT05. In this case, the current control switch BT14 may be included in the control signal S1. By controlling the polarity of the voltage applied to the terminal pair BT01, the voltage applied to the terminal pair BT02 can be controlled. The current control switch BT14 controls the polarity of the applied voltage. 2 controls the direction of the current flowing to the charging battery cell group.

[0392] FIG. 27 shows a configuration of the switching circuit BT04 and the switching circuit BT05, which is different from that shown in FIG. FIG. 10 is a circuit diagram showing an example.

[0393] In FIG. 27, the switching circuit BT04 includes a plurality of transistor pairs BT21 and a bus BT2 The bus BT24 is connected to the terminal A1. The transistor pair BT25 is connected to the terminal A2. Each of them is branched by a transistor BT22 and a transistor BT23. One of the source and drain of the transistor BT22 is connected to the bus BT24. One of the source and drain of the transistor BT23 is connected to the bus BT25. , the other ends of the plurality of transistor pairs BT21 are connected to the two adjacent battery cells BT09. Among the multiple transistor pairs BT21, the transistor located at the most upstream position is The other end of the transistor pair BT21 is connected to the battery cell BT09 located at the most upstream of the battery section BT08. The positive terminal of the transistor pair BT21 is connected to the most downstream terminal of the transistor pair BT21. The other end of the transistor pair BT21 is connected to the battery cell BT08 located at the most downstream side. It is connected to the negative terminal of 09.

[0394] The switching circuit BT04 switches the transistors BT22 and BT23 in response to the control signal S1. By switching the conductive / non-conductive state of the transistor pair BT23, the The connection destination is switched to either terminal A1 or terminal A2. If BT22 is conductive, transistor BT23 is non-conductive and is connected to On the other hand, if the transistor BT23 is in a conducting state, the transistor BT2 Transistor BT22 and transistor BT23 are in a non-conductive state and are connected to terminal A2. Which of the resistors BT23 is in a conductive state is determined by a control signal S1.

[0395] To connect the terminal pair BT01 to the discharge battery cell group, two transistor pairs BT21 are used. Specifically, the connection of the two transistor pairs BT21 is controlled based on the control signal S1. By determining the destinations, the discharge battery cell group and terminal pair BT01 are connected. The two transistor pairs BT21 are connected to terminal A1 and terminal B2. A2 is controlled by the control signal S1.

[0396] The switching circuit BT05 includes a plurality of transistor pairs BT31, a bus BT34, and a bus B The bus BT34 is connected to the terminal B1. The bus BT35 is , and the terminal B2. One end of each of the plurality of transistor pairs BT31 is connected to the transistor The output is branched by transistor BT32 and transistor BT33. One end of the branched signal is connected to a bus BT34. One end of the branched transistors is connected to a bus BT35. The other end of each of the terminals BT09 is connected between two adjacent battery cells BT09. Among the several transistor pairs BT31, the other end of the transistor pair BT31 located at the most upstream position is The positive terminal of the battery cell BT09 located at the most upstream position of the battery unit BT08 is connected to the positive terminal of the battery cell BT09. In addition, among the plurality of transistor pairs BT31, the transistor pair BT31 located at the most downstream position The other end is connected to the negative terminal of the battery cell BT09 located at the most downstream side of the battery unit BT08. do.

[0397] The switching circuit BT05 switches the transistors BT32 and BT33 in response to the control signal S2. By switching the conductive / non-conductive state of the transistor pair BT33, the The connection destination is switched to either terminal B1 or terminal B2. If BT32 is conductive, transistor BT33 is non-conductive and is connected to Conversely, if the transistor BT33 is in a conductive state, the transistor BT3 Transistor BT32 and transistor BT33 are in a non-conductive state and are connected to terminal B2. Which of the resistors BT33 is in a conductive state is determined by a control signal S2.

[0398] To connect the terminal pair BT02 to the charging battery cells, two transistor pairs BT31 are used. Specifically, the connection of the two transistor pairs BT31 is controlled based on the control signal S2. By determining the destinations, the charging battery cell group and terminal pair BT02 are connected. The two transistor pairs BT31 are connected to terminals B1 and B2, respectively. It is controlled by the control signal S2 to become the child B2.

[0399] The two transistor pairs BT31 are connected to the terminal pair BT02. Specifically, terminal B1 is the positive terminal and terminal B2 is the negative terminal. When a voltage such as this is applied to the terminal pair BT02, the upstream transistor pair BT31 When the transistor BT32 is turned on, the transistor BT33 is turned off. On the other hand, the downstream transistor pair BT31 is controlled by the control signal S2 as follows: The transistor BT33 is controlled to be in a conductive state and the transistor BT32 is controlled to be in a non-conductive state. The terminal B1 is negative and the terminal B2 is positive. When voltage is applied to terminal pair BT02, the upstream transistor pair BT31 so that the transistor BT33 is in a conducting state and the transistor BT32 is in a non-conducting state. On the other hand, the downstream transistor pair BT31 is controlled by the control signal S2. The control signal S is set to ON so that the transistor BT32 is in a conducting state and the transistor BT33 is in a non-conducting state. In this way, the same voltage is applied between the terminal pair BT02 and the charging battery cell group. The terminals with the same polarity are connected together. The direction of the current flowing from the terminal pair BT02 is as follows: The charge is controlled so as to charge the battery cell group.

[0400] The transformer control circuit BT06 controls the operation of the transformer circuit BT07. is the number of battery cells BT09 included in the discharge battery cell group and the number of battery cells BT09 included in the charge battery cell group. A transformer signal S3 for controlling the operation of the transformer circuit BT07 is generated based on the number of the buffer cells BT09. and outputs it to the transformer circuit BT07.

[0401] The number of battery cells BT09 included in the discharge battery cell group is the same as the number of battery cells BT09 included in the charge battery cell group. If the number of battery cells is greater than the number of BT09, an excessively large charging voltage will be applied to the charging battery cell group. Therefore, the voltage transformer control circuit BT06 controls the charging voltage The transformer circuit BT07 is designed to lower the discharge voltage (Vdis) to a level that allows the battery cell group to be charged. The transformer outputs a transform signal S3 that controls the

[0402] In addition, the number of battery cells BT09 included in the discharge battery cell group is If the number of battery cells BT09 is less than the number of battery cells BT09, the charging capacity required to charge the charging battery cell group is Therefore, the voltage transformer control circuit BT06 controls the charging battery cell group to Transformer circuit B is used to boost the discharge voltage (Vdis) within a range where excessive charging voltage is not applied. It outputs a transformer signal S3 that controls T07.

[0403] The voltage value that constitutes the excessive charging voltage is the voltage of the battery cell BT09 used in the battery module BT08. The voltage can be determined in consideration of the product specifications, etc. The voltage thus generated is applied to the terminal pair BT02 as the charging voltage (Vcha).

[0404] Here, an example of the operation of the transformer control circuit BT06 in this embodiment is shown in FIGS. 28(A) to 28(C) . 28(A) to (C) are the same as those described in FIGS. 25(A) to (C). An example of the operation of the voltage transformer control circuit BT06 corresponding to the power battery cell group and the charge battery cell group will be explained. 28(A) to 28(C) are conceptual diagrams illustrating the battery control unit BT41. As described above, the battery control unit BT41 has the terminal pair BT01 and the terminal pair BT02. BT02, a switching control circuit BT03, a switching circuit BT04, and a switching circuit BT 05, a voltage transformation control circuit BT06, and a voltage transformation circuit BT07.

[0405] In the example shown in FIG. 28(A), three consecutive high voltages are generated as explained in FIG. 25(A). In this case, the high-voltage cells a to c and one low-voltage cell d are connected in series. As explained using A), the switching control circuit BT03 discharges the high voltage cells a to c. The low-voltage cell d is determined as the battery cell group, and the low-voltage cell d is determined as the charging battery cell group. The control circuit BT06 determines the number of battery cells BT09 included in the discharge battery cell group as a reference. Based on the ratio of the number of battery cells BT09 included in the charging battery cell group, the discharge voltage (Vd Calculate the conversion ratio N from the current (V is ) to the charging voltage (V cha ).

[0406] The number of battery cells BT09 included in the discharge battery cell group is the same as the number of battery cells BT09 included in the charge battery cell group. If the number of battery cells is greater than BT09, the discharge voltage is directly transferred to the terminal pair BT02 without being transformed. If the voltage is applied as is, the battery cell BT09 included in the charging battery cell group will be charged via the terminal pair BT02. Therefore, in the case shown in Figure 28(A), Now, let's make the charging voltage (Vcha) applied to the terminal pair BT02 lower than the discharging voltage. Furthermore, in order to charge the battery cell group, the charging voltage must be The voltage must be greater than the total voltage of the battery cells BT09 included in the transformer control circuit. BT06 is the number of charge cells when the number of battery cells BT09 included in the discharge battery cell group is used as the standard. The conversion ratio N is set to be larger than the ratio of the number of battery cells BT09 included in the battery cell group.

[0407] The transformer control circuit BT06 determines the number of battery cells BT09 included in the discharge battery cell group as a standard. When the conversion ratio N is It is preferable to make it 1 to 10% larger. At this time, the charging voltage is higher than the voltage of the charging battery cell group. However, in reality, the charging voltage is equal to the voltage of the battery cell group. The voltage control circuit BT06 is configured to equalize the voltage of the charging battery cell group with the charging voltage according to the conversion ratio N. This current flows through the transformer control circuit BT06 to charge the battery cell group. The value set in

[0408] In the example shown in FIG. 28(A), the number of battery cells BT09 included in the discharge battery cell group is Since there is only one battery cell BT09 in the charging battery cell group, the voltage control circuit The circuit BT06 calculates a value slightly larger than 1 / 3 as the conversion ratio N. The circuit BT06 converts the discharge voltage into a charging voltage by converting the voltage into a charging voltage according to the conversion ratio N. 3 to the transformer circuit BT07. Then, the transformer circuit BT07 outputs The transformed charging voltage is applied to the terminal pair BT02. The battery cell BT09 included in the charging battery cell group is charged by the charging voltage.

[0409] In addition, in the examples shown in FIG. 28(B) and FIG. 28(C), as in FIG. 28(A), the conversion ratio In the examples shown in FIG. 28(B) and FIG. 28(C), the number of discharged battery cells included in the discharged battery cell group is calculated. The number of battery cells BT09 included in the charging battery cell group is less than or equal to the number of battery cells BT09 included in the charging battery cell group. Therefore, the conversion ratio N is equal to or greater than 1. In this case, the transformer control circuit BT06 is configured as follows: It outputs a voltage transformation signal S3 that boosts the discharge voltage and converts it into a charge voltage.

[0410] The transformer circuit BT07 generates a discharge voltage applied to the terminal pair BT01 based on the transformer signal S3. The transformer circuit BT07 converts the converted charging voltage into a terminal pair BT 02. Here, the transformer circuit BT07 is connected between the terminal pair BT01 and the terminal pair BT02. This allows the transformer circuit BT07 to be electrically isolated from the most discharged battery cells. The absolute voltage of the negative terminal of the downstream battery cell BT09 and the lowest voltage of the charging battery cell group This prevents a short circuit due to the difference in absolute voltage between the negative terminal of the battery cell BT09 located downstream. Furthermore, as described above, the transformer circuit BT07 converts the voltage of the discharge battery cell group based on the transformer signal S3. The total voltage, the discharge voltage, is converted into a charge voltage.

[0411] The transformer circuit BT07 is, for example, an isolated DC (Direct Current)-D In this case, the transformer control circuit BT06 is an isolated DC -The signal that controls the on / off ratio (duty ratio) of the DC converter is the transformer signal S3. By outputting this signal, the charging voltage converted by the transformer circuit BT07 is controlled.

[0412] There are three types of isolated DC-DC converters: flyback, forward, and RCC. (Ring Choke Converter) method, push-pull method, half There are bridge and full bridge types, but depending on the size of the desired output voltage, An appropriate method is selected depending on the situation.

[0413] The configuration of the transformer circuit BT07 using an isolated DC-DC converter is shown in Figure 29. The DC-DC converter BT51 has a switch unit BT52 and a transformer unit BT53. The switch BT52 switches the operation of the isolated DC-DC converter on and off. A switch, such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistors and bipolar transistors The switch unit BT52 is realized by using a transformer or the like. The isolated DC-DC converter is driven based on the transformer signal S3 that controls the on / off ratio. The switch unit BT51 periodically switches between the on state and the off state. Various configurations are possible depending on the type of isolated DC-DC converter used. The unit BT53 converts the discharge voltage applied from the terminal pair BT01 into a charge voltage. The transformer unit BT53 operates in conjunction with the on / off state of the switch unit BT52. The discharge voltage is converted into a charge voltage according to the on / off ratio. This charge voltage is In the switching period of 52, the longer the ON time, the larger the capacitance. The time during which the voltage is in the ON state is short in the switching period of the switch unit BT52. When using an isolated DC-DC converter, the transformer BT53 Within this, the terminal pair BT01 and the terminal pair BT02 can be insulated from each other.

[0414] The processing flow of power storage device BT00 in this embodiment will be described with reference to FIG. 10 is a flowchart showing the flow of processing by power storage device BT00.

[0415] First, the power storage device BT00 acquires the voltage measured for each of the plurality of battery cells BT09 ( Step S101). Then, the power storage device BT00 aligns the voltages of the plurality of battery cells BT09. It is determined whether the start condition for the operation is satisfied (step S102). For example, the difference between the maximum and minimum voltages measured for each of the plurality of battery cells BT09 is If this start condition is not met (step S 102:NO), the voltage of each battery cell BT09 is balanced, so the storage On the other hand, if the start condition is met (step S102: YES), the power storage device BT00 executes a process for aligning the voltages of the battery cells BT09. In this process, power storage device BT00 performs the following on the basis of the measured voltage of each cell: It is determined whether each battery cell BT09 is a high-voltage cell or a low-voltage cell (step S103). Then, the power storage device BT00 determines the discharge battery cell group and the charge battery cell group based on the determination result. Furthermore, the power storage device BT00 determines the discharge battery cell group to be discharged (step S104). A control signal S1 sets the terminal pair BT01 to the terminal pair BT02, and a control signal S2 sets the terminal pair BT01 to the terminal pair BT02. A control signal S2 is generated to set the connection destination of the child pair BT02 (step S105). The device BT00 transmits the generated control signals S1 and S2 to the switching circuits BT04 and BT05. Then, the switching circuit BT04 outputs the signal to the terminals The terminal pair BT01 is connected to the discharge battery cell group, and the terminal pair BT0 2 and the discharge battery cell group are connected (step S106). The number of battery cells BT09 included in the discharge battery cell group and the number of battery cells included in the charge battery cell group are Based on the number of the BT09, a transformed signal S3 is generated (step S107). Based on the transformation signal S3, the power storage device BT00 changes the discharge voltage applied to the terminal pair BT01. is converted into a charging voltage and applied to the terminal pair BT02 (step S108). The charge of the battery cells is transferred to the battery cells.

[0416] In addition, in the flowchart of FIG. 30, multiple steps are listed in order, but each step The order in which the steps are performed is not limited to the order in which they are listed.

[0417] As described above, according to this embodiment, when transferring charges from the discharge battery cell group to the charge battery cell group, Like the capacitor method, the charge from the discharged battery cells is first stored and then transferred to the charging battery cells. This eliminates the need for a structure that emits charge to a group of electrons. In addition, the switching circuit BT04 and the switching circuit BT05 Therefore, among the discharge battery cell group and the charge battery cell group, the battery cells connected to the transformer circuit are respectively Can be switched individually.

[0418] Furthermore, the number of battery cells BT09 included in the discharge battery cell group is and the number of battery cells BT09 included in the charging battery cell group. The applied discharge voltage is converted into a charge voltage and applied to the terminal pair BT02. Regardless of the selection of the battery cell BT09 on the supply and charging sides, the charge transfer can be performed without any problems. It can be realized.

[0419] Furthermore, OS transistors are used for the transistors BT10 and BT13. As a result, leakage from the battery cell BT09 that does not belong to the charging battery cell group or the discharging battery cell group occurs. This reduces the amount of charge in the battery cell BT0 that does not contribute to charging or discharging. The decrease in capacitance of the OS transistor can be suppressed. This causes the temperature of the battery cell BT09 to rise. However, normal operation, such as switching between conductive and non-conductive states according to the control signals S1 and S2, is possible. It can be made to work. [Example]

[0420] In this example, "particles containing lithium manganese composite oxide" according to one embodiment of the present invention were prepared. The fabrication procedure is explained based on the flowchart in Figure 1.

[0421] <Synthesis> First, particles containing lithium manganese composite oxide were prepared.

[0422] (Step S11) First, Li2CO3, MnCO3, and NiO were used as starting materials. The molar ratio of Li2CO3:MnCO3:NiO is 0.84:0.8062:0 It weighed out to 0.318.

[0423] (Step S12) Next, ethanol was added to the starting materials, and then the mixture was mixed using a bead mill. The processing chamber of the bead mill was rotated at a peripheral speed of 10 m / s and the mixing time was 30 minutes. A mixed raw material was obtained.

[0424] (Step S13) Next, the mixed raw material was subjected to a heat treatment. The heat treatment was carried out in an air atmosphere at a heating temperature of 7 By performing this at 5°C, the ethanol contained in the mixed raw materials is evaporated, and the mixed raw materials are I received the fee.

[0425] (Step S14) Next, the mixed raw materials were placed in a crucible and fired. The firing process was carried out in a dry oven with a flow rate of 10 L / min. By firing in an air atmosphere at 1000°C for 10 hours, Lithium manganese composite oxide was synthesized.

[0426] (Step S15) Next, a crushing process is carried out to remove the sintering of the lithium manganese composite oxide, which has sintered primary particles. The crushing process was carried out by adding ethanol to the sintered lithium manganese composite oxide. The treatment chamber of the zeal mill was rotated at a peripheral speed of 12 m / s, and treatment was carried out for 4 hours to obtain powdered lithium manganese. A complex oxide of cancer was obtained.

[0427] (Step S16) Next, the crushed lithium manganese composite oxide was subjected to a heat treatment. By heating at 75°C in a gas atmosphere, the The ethanol was evaporated. Then, the obtained lithium manganese composite oxide was placed in a crucible and fired. The firing conditions were 800°C, 300°C, and 10 L / min dry air. After firing, the powder obtained was designated as Sample A. Sample A has the composition formula Li 1.68 Mn0 .8062 Ni 0.318 It is expressed as O3, but the composition may deviate from this.

[0428] <Coating layer> Next, a carbon-containing layer was formed on the obtained sample A. First, 0.1 g of graphene oxide was To the mixture, 1 g of water was added and kneaded using a kneader to prepare a dispersion solution of graphene oxide. The kneading speed was 2000 rpm, and the kneading time was 5 minutes per kneading, which was repeated 4 times. In the first kneading, the amount of water is 3 / 10 of the total amount, and in the second kneading, add another 3 / 10 Add 1 / 3 of the mixture, and on the third knead, add another 3 / 4 of the mixture, and on the fourth knead, add another 1 / 4 of the mixture. One-third of the mixture was added and kneading was continued.

[0429] (Step S17) Next, 5 g of sample A was added to the prepared dispersion solution, and 1.1 g of water was further added to solidify the solution. The kneading was carried out four times. For the hard kneading, a kneader was used, the rotation speed was 2000 rpm, and the kneading time was The resulting mixture was dried under reduced pressure at 50°C in a bell jar. The graphene oxide was then crushed in an alumina mortar to obtain a lithium manganese composite oxide. Thus, sample B was obtained.

[0430] (Step S18) Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the agent, and a mixed solution of ethanol and water was used as the solvent. The concentration of ethanol in the solution was 80% by volume. The weight of the manganese-ascorbic acid composite oxide was 16.87 wt% and the weight of the lithium hydroxide The resulting powder was added to the reducing solution and heated to 60°C. The mixture was reduced by treating with HCl for 3 hours.

[0431] (Step S19) Next, the resulting solution was filtered by suction. Filter paper was used, then washed and filtered again.

[0432] Next, the powder obtained by filtration was crushed in a mortar. Then, the mixture was heated at 170°C under reduced pressure for 10 minutes. It was dried for an hour.

[0433] Through the above steps, a powder of lithium manganese composite oxide with graphene formed on the surface was obtained. (Sample C) was prepared.

[0434] <Preparation of electrodes> Next, an electrode was fabricated using the obtained sample C. Sample C was used as the active material, and the conductive additive Acetylene black (AB) was used as the carrier and PVdF was used as the binder.

[0435] First, PVdF and AB were mixed with a polar solvent, NMP (N-methyl-2-pyrrolidone). The rotation speed of the kneading was 2000 rpm, and the kneading time was 5 minutes. Sample C was added as a material and kneaded. The kneading speed was 2000 rpm and the kneading time was 1 This was repeated five times, with each cycle lasting 5 minutes. NMP was then added and kneaded. The kneading speed was The mixing was performed twice, with the mixing speed at 2000 rpm and the mixing time at 10 minutes. The electrode mixture composition was mixed in a weight ratio of Sample C:A. The B:PVdF ratio was 90:5:5.

[0436] Next, the electrode mixture composition was applied onto an aluminum foil as a current collector. The aluminum foil surface was first coated with an undercoat. After that, it was dried in a ventilated oven at 80°C. and dried for 30 minutes.

[0437] Next, the electrode was pressed using a roll press. The pressing pressure was adjusted to reduce the thickness by 20%. The pressing temperature was set to 120°C. did.

[0438] Then, a further heat treatment was carried out under the conditions of a reduced pressure atmosphere (1 kPa) at 270°C. The above process was carried out for 10 hours. An electrode X having particles containing manganese composite oxide was obtained.

[0439] <Half-cell characteristics> Next, a half cell was fabricated using the obtained electrode X. A coin cell was used as the cell. In addition, lithium was used as the counter electrode of the half cell. Using F6, a mixture of aprotic organic solvents EC and DEC was prepared in a volume ratio of 1:1. A mixed solution was used, and polypropylene (PP) was used as the separator.

[0440] Next, the fabricated half cell was subjected to aging at 25°C. The first charge / discharge was performed at a constant voltage of 150mAh / g at 0.1C (current density 30mA / g). After charging, discharge at a constant current of 0.1C with a lower limit of 2V. After charging at a constant current of 80mAh / g, discharge at a constant current of 0.1C and a lower limit of 2V for three cycles. As a test, a constant current charge of 210mAh / g was performed at 0.1C, and then a constant current charge of 0.1C and a lower limit of 2V was performed. The fourth time, the battery was discharged at a constant current of 240mAh / g at 0.1C. The fifth time, a constant current discharge of 270mAh / g was performed at 0.1C with a lower limit of 2V. After constant current charging, constant current discharging was performed at 0.1C with a lower limit of 2V.

[0441] After the above aging, the charge-discharge characteristics were measured at 25°C. The charge was performed at a constant current of 0.1C and an upper voltage of 4.8V, and the discharge was performed at a constant current of 0.1C and a lower voltage of 2V. The obtained charge-discharge curves are shown in Figure 31. By using particles containing oxides, a high discharge capacity exceeding 300 mAh / g can be obtained. This was possible. [Example]

[0442] In this example, "particles having lithium manganese composite oxide" according to one embodiment of the present invention , Scanning Transmission Electron Microscopy (STEM) electron microscopy), energy dispersive X-ray spectroscopy (EDX) Energy Dispersive X-ray spectroscopy and ultramicroscopy The evaluation was carried out by electron diffraction.

[0443] First, a sample H-1 and an electrode H-3 were prepared for observation.

[0444] For sample H-1, steps S11 to S17 shown in FIG. See Example 1 for the conditions of the loop.

[0445] For the electrode H-3, after steps S11 to S19 shown in FIG. The obtained sample (hereinafter referred to as sample H-2) was used to prepare electrode H-3. The conditions for producing the electrode were as described in Example 1 for electrode X.

[0446] Specimen H-1 and electrode H-3 were analyzed using FIB (Focused Ion Beam) After thinning using a focused ion beam processing and observation system, scanning transmission Scanning Transmission Electron Microscopy (STEM) The TEM observation images are shown in Figure 32. Figure 32(A) shows the observation results for sample H-1, and (B) shows the observation results for electrode H-3. 1. A cross section of a particle 141 having a lithium manganese composite oxide, which is one embodiment of the present invention. was observed.

[0447] Next, EDX evaluation was performed on the locations numbered 1 to 5 shown in Figures 32(A) and 32(B). The evaluation results for sample H-1 are shown in Table 1, the evaluation results for electrode H-3 are shown in Table 2, and Tables 1 and 2 also show the distance from the particle surface to each measurement point. 47 to 51 show the spectra at each measurement point. ) is measurement point 1, (B) is measurement point 2, (A) is measurement point 3, (B) is measurement point 4, and (C) is measurement point 5. (A) shows the spectrum at measurement point 5. For electrode H-3, (B) shows the spectrum at measurement points 1 and Measurement point 2 in Figure 50(A), measurement point 3 in Figure 50(B), measurement point 4 in Figure 51(A), measurement point 51 in Figure 51(B) The spectrum of 5 is shown.

[0448] [Table 1]

[0449] [Table 2]

[0450] In Tables 1 and 2, the sum of the atomic ratios of manganese, nickel, and oxygen is The values ​​were normalized to approximately 100%.

[0451] Next, the atomic ratios of manganese, nickel, and oxygen obtained by EDX are b and c, respectively. , and d, and the value of d÷(b+c) (=A) was calculated for each evaluation point. The distance from the particle surface is plotted on the vertical axis, and the value of A is plotted on the vertical axis. The plotted graph is shown in Figure 33.

[0452] First, the region less than 10 nm from the surface will be described. The value of A at the measurement point of 2.2 nm from the surface for electrode H-3 was 1.6. It was 1.9.

[0453] Next, the region 20 nm or more from the surface will be described. The value of A at the measurement point m is 2.4, and at measurement points at a greater distance from the surface The value of A was also larger than 2.4. For electrode H-3, the A value was measured at a point 22 nm from the surface. The value of is 2.9, and even at measurement points farther from the surface, the value of A is 2. It was bigger than 9.

[0454] From the above, the ratio A of the number of oxygen atoms to the sum of the number of manganese and nickel atoms is It can be seen that the values ​​differ between the area close to the particle and the area closer to the particle. In one embodiment of the present invention, the particles having the lithium manganese composite oxide have different values ​​of A, at least Both have two regions, and the region closer to the surface has a smaller value of A. There may be cases where this is the case.

[0455] The value of A in the region near the surface, for example, the region less than 10 nm from the surface, is than the value of A in the region closer to the interior of the particle, for example, the region 20 nm or more from the surface. small.

[0456] Next, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) of electrode H-3 was performed. :High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (TEM) images were obtained. The results are shown in Fig. 34. Fig. 34(A) shows the area 142 surrounded by a solid line in Fig. 32(B). (B) shows the observation results of the area 143 surrounded by the solid line in FIG. 32(B). For HAADF-STEM imaging, spherical aberration correction is required. The TEM images were observed using the TEM Corrector function. The combined analysis image of the bright field image and the diffraction pattern is called a high-resolution TEM image. High-resolution TEM images using the surface aberration correction function are specifically called Cs-corrected high-resolution TEM images. To obtain s-corrected high-resolution TEM images, an atomic resolution analytical electron microscope (JE) manufactured by JEOL Ltd. was used. The M-ARM200F was used. The acceleration voltage was 200 kV. On the farther side from the surface of the child, bright spots form layers V1 and V2, and layers V1 and The figure shows a layer T1 located between layers V1 and V2 and containing dimmer bright spots compared to layers V1 and V2. The distance between layers V1 and T1 is roughly equal to the distance between layers T1 and V2. Compared to nickel and nickel, lithium has a smaller atomic number, making it suitable for HAADF-STEM observation. Therefore, for example, layer T1 is a layered rock salt structure. Therefore, it is possible that the layer on the (0 0 1) plane is mainly formed by lithium.

[0457] Next, layers U1 to U2, which are located in a region closer to the surface of the particle than layers V1, V2 and T1, are Layer U3 is shown. Layers U1 to U3 are all formed by bright spots of roughly the same brightness. Here, the distance between layers U1 and U3 is roughly equal to the distance between layers V1 and V2. In layer U2, which is sandwiched between layers U1 and U3, the brightness of the bright spots is brighter than in layer T1. Therefore, for example, the abundance ratio of manganese and nickel is higher in layer U2 compared to layer T1. There is a possibility that this is the case.

[0458] Next, at measurement point 1 (*1) and measurement point 2 (*2) in the TEM photograph shown in Figure 39, The electron microdiffraction was evaluated. Measurement point 2 shown in Figure 39 is closer to the surface of the particle, and the surface of the particle Measurement point 1 is closer to the inside of the particle than measurement point 2. The results of the electron microbeam diffraction at each measurement point are shown in Figure 35. Figure 35(A) shows the results of the electron microbeam diffraction at each measurement point. The electron microbeam diffraction results for measurement point 1 shown in FIG. 35(A) and measurement point 2 shown in FIG. 35(B) are respectively.

[0459] In addition, the actual measured values ​​of the positional relationship (distance, angle) of the spots in the obtained diffraction pattern were The crystal structure of Li2MnO3 corresponds well to that shown in DS card No. 84-1634. More specifically, the diffraction pattern at measurement point 1 (FIG. 35(A)) shows the above The diffraction pattern of the crystal structure with the incident direction [-1 -1 0] and the measurement point 2 (Figure 35( The diffraction pattern of B)) is different from the diffraction pattern of the incident direction [3 2 -3]. On the right side of each figure, there is a corresponding figure for JCPDS card No. 84-1634. The corresponding distances and angles are shown. The actual measured values ​​are shown on the left side of each figure.

[0460] In addition, electron diffraction observation was performed on particles different from those shown in Figure 39. Specifically, At measurement point 1(*1) and measurement point 2(*2) in the TEM photograph shown in Fig. 1, ultrafine electron diffraction was performed. Measurement point 2 shown in Figure 40 is closer to the particle surface, within 10 nm from the particle surface. Measurement point 1 is closer to the interior of the particle than measurement point 2. The results of the electron microbeam diffraction at each measurement point are shown in Figure 41. Figure 41(A) shows the electron microbeam diffraction pattern at measurement point 1 shown in Figure 40. 41(B) shows the results of electron microbeam diffraction at measurement point 2.

[0461] In addition, the actual measured values ​​of the positional relationship (distance, angle) of the spots in the obtained diffraction pattern were The crystal structure of Li2MnO3 corresponds well to that shown in DS card No. 84-1634. More specifically, the diffraction pattern at measurement point 1 (FIG. 41(A)) is The diffraction pattern of the crystal structure with the incident direction of

[0100] and the measurement point 2 (Figure 41(B)) ) diffraction pattern corresponds well with the diffraction pattern for the incident direction [3 2 -3]. On the right side of each figure, the number corresponding to JCPDS card No. 84-1634 is shown. The distance and angle are shown. The actual measured values ​​are shown on the left side of each figure.

[0462] As described in the first embodiment, the first and second regions are made of layered rock salt. It is preferable that the first region has a <1 1 0> orientation and the second region has a <3 2 -3> orientation that are parallel to each other. For example, the planar arrangement of the lithium and manganese containing layers or the oxygen layers is roughly maintained. Since the two regions can be joined while still retaining their original shape, it can be said that the two regions are well-matched. [Example]

[0463] In this example, the relationship between the surface area and characteristics of particles according to one embodiment of the present invention will be described.

[0464] In the process of step S15 shown in Example 1, the crushing conditions were varied, and the surface of the obtained particles was The relationship with the product was evaluated.

[0465] Particles according to one embodiment of the present invention were prepared according to steps S11 to S19 in FIG. Here, for the crushing step shown in step S15, the crushing conditions shown in Table 2 were used, and the sample Samples Z-1 to Z-6 were prepared. Samples Z-4 to Z-6 had a coating layer No formation was performed.

[0466] [Table 3]

[0467] The specific surface areas of the obtained samples Z-1 to Z-6 were evaluated, and the results are shown in Table 3.

[0468] Next, electrodes were fabricated using the obtained samples Z-1 to Z-6. The electrode fabrication conditions were as follows: , see Example 1.

[0469] Next, the prepared electrode was used in the same conditions as in Example 1, using the electrolyte, separator, and counter electrode. A half cell was prepared using a coin cell.

[0470] Next, the fabricated half-cell was charged and discharged. The charging conditions were a constant current of 30 mA / g for 4 The upper limit was 0.8V, and the discharge conditions were a constant current of approximately 30mA / g with a lower limit of 2.0V. The resulting discharge capacities are shown in Table 3.

[0471] As the peripheral speed increased, the specific surface area tended to increase. Under the conditions prepared, the larger the specific surface area, the higher the capacity. 4.0m 2 / g, the resulting discharge capacity was 274mAh / g, and the specific surface area of ​​sample Z-3 was 14 .8m 2 / g and the resulting discharge capacity was 291mAh / g, both of which were very high values. .

[0472] On the other hand, for samples without a coating layer, the specific surface area increases as the peripheral speed increases. However, sample Z-5 has a specific surface area of ​​14.6 m 2 / g, and discharge capacity is 91mAh / g , and 30.3 m for sample Z-6. 2 / g, the discharge capacity is low at 101mAh / g, and the beads For example, a damaged layer was formed on the particle surface due to the crushing treatment using a centrifuge. It is possible that part of the surface layer has been scraped off. By forming a coating layer, the surface area This resulted in increased efficiency and high capacity. [Example]

[0473] In this example, "particles containing lithium manganese composite oxide" of one embodiment of the present invention was used. Then, the thin storage battery described in Embodiment 2 was manufactured.

[0474] <Preparation of positive electrode> First, "particles containing lithium manganese composite oxide" according to one embodiment of the present invention were prepared.

[0475] First, steps S11 to S14 shown in Example 1 were carried out.

[0476] (Step S15) Next, the bead mill was subjected to crushing treatment. The peripheral speed was 8 m / s per 100 g for 12 hours. Ethanol was used as the solvent.

[0477] (Step S16) Next, the crushed lithium manganese composite oxide was subjected to a heat treatment and dried. The obtained powder was designated as Sample A2. Then, the obtained lithium manganese composite oxide was placed in a crucible. The firing conditions were 8 hours in a dry air atmosphere at 10 L / min. 00℃ for 3 hours.

[0478] (Step S17) Next, a carbon-containing layer was formed on the obtained sample A2. Then, 50 ml of water was added and the mixture was kneaded using a kneader to prepare a dispersion solution of graphene oxide. Next, 200 g of sample A2 was added to the prepared dispersion solution, and 90 ml of water was further added. The mixture was kneaded twice using a kneader at a rotation speed of 80 rpm for a kneading time of 10 min. The mixture was dried in a forced-air oven at 50°C for 30 minutes. After drying, it was crushed in an alumina mortar to obtain a lithium manganese composite coated with graphene oxide. A composite oxide, sample B2, was obtained.

[0479] (Step S18) Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the agent, and an 80% vol. ethanol aqueous solution was used as the solvent. The weight of the graphene oxide-coated lithium manganese composite oxide was The reducing solution was prepared by adding 16.87 wt% phosphoric acid and 3.9 wt% lithium hydroxide. The sample B2 was placed in a reducing solution and reduced at 60°C for 3 hours.

[0480] (Step S19) Next, the solvent was separated from the obtained solution using a centrifuge, and the separated liquid was discarded. The process of adding pure water to wash the mixture, centrifuging the mixture, and then discarding the separated liquid was repeated four times. The rotation speed for separation was 9000 rpm, and the time was 3 minutes per separation. Next, the solvent was added to the separated sample. Pure water was added to adjust the concentration to 121 g / l to obtain a solution. The liquid was heated to 150°C and spray-dried.

[0481] Next, the powder obtained by the spray drying process was dried under reduced pressure for 10 hours.

[0482] Through the above steps, a powder of lithium manganese composite oxide with graphene formed on the surface was obtained. (Sample C2) was prepared.

[0483] Next, the positive electrode of a storage battery was fabricated using Sample C2. Acetylene black (AB) was used as an auxiliary agent, and PVdF was used as a binder. The active material, AB, and PVdF were mixed in the following ratio: active material:AB:PVdF=90:5:5 (wei ght%).

[0484] The active material, AB, PVdF, and NMP were mixed using a mixer to prepare a slurry. Then, the coating was applied to a 20 μm thick aluminum foil that had been undercoated using a continuous coating machine. The slurry was applied to one side of an aluminum foil using a drying oven at 70°C. After drying for 0 minutes, drying was carried out at 90°C for 10 minutes.

[0485] After that, further heat treatment was carried out. The heat treatment conditions were a reduced pressure atmosphere (1 KPa), 250 After that, the pressing pressure was set to 1.5 MPa, and the pressing temperature was set to 1.5 MPa. The temperature was set to 120°C. By the above steps, the "lithium manganese composite" according to one embodiment of the present invention was obtained. A positive electrode X2 having particles containing an oxide was obtained. The amount of the active material carried in the obtained positive electrode was 7.2 mg / cm 2 It was.

[0486] Next, the positive electrode X2 thus produced and a negative electrode using graphite as the active material were used to conduct the test shown in the second embodiment. A thin storage battery, storage battery A, was fabricated, and the positive electrode X2 was aged.

[0487] The exterior of battery A was made of aluminum film covered with heat-sealed resin. LiPF6 was used as the salt, and a mixture of EC, DEC, and EMC was used as the solvent. In addition, PP was used for the separator.

[0488] Next, the fabricated storage battery A was pressed at 20 MPa using a press machine while charging and discharging. The discharge was repeated three times. The lower limit of the discharge voltage was set to 2V.

[0489] <Preparation of negative electrode> Next, a negative electrode for a storage battery was fabricated. SiO was used as the active material and A was used as the conductive additive. B used polyimide as a binder.

[0490] First, SiO:AB:polyimide precursor = 80:5:15 (weight%) SiO, AB, and the polyimide precursor were weighed as follows. A solution with a concentration of 13.7 wt % using NMP as the solvent was used.

[0491] First, SiO and AB were mixed in a kneader. Then, NMP was added little by little, and the mixture was stirred in a planetary mixer. The mixture was kneaded in a kneader to prepare a paste. The total amount of MP was adjusted so that the solid content of the paste was about 60%. This refers to kneading at high viscosity. By kneading at high viscosity, the dispersibility of the active material and conductive additive is improved. It is possible.

[0492] Next, a polyimide precursor solution using NMP as a solvent was added to the prepared paste and mixed. The mixture was kneaded using a kneader. A slurry was prepared by the above steps. The solid content was 40% by weight.

[0493] Next, the slurry was applied to one side of a rolled copper foil with a thickness of 18 μm using a continuous coating machine. After that, the solvent was evaporated by heat treatment in a drying oven. The resulting product was then heat-treated at 75°C for 180 seconds. The negative electrode was designated as negative electrode Y. The amount of the active material carried on the obtained negative electrode Y was 1.9 mg / cm. 2 It was.

[0494] Next, a thin film was fabricated using the fabricated negative electrode Y and a positive electrode using lithium cobalt oxide as the active material. A storage battery B was fabricated, and the negative electrode Y was subjected to aging.

[0495] The exterior of battery B was made of aluminum film covered with heat-sealed resin. In this study, LiPF6 was used as the salt and a mixture of EC and DEC was used as the solvent. In addition, PP was used for the separator.

[0496] Next, the fabricated storage battery B was charged and discharged.

[0497] <Creating Battery C> The exterior packaging of the storage battery A was opened, and the positive electrode X2 was taken out. The exterior packaging of the storage battery B was also opened. Then, the negative electrode Y was taken out.

[0498] Next, a storage battery C was fabricated using the removed positive electrode X2 and negative electrode Y.

[0499] The exterior of the storage battery C was an aluminum film covered with a heat-sealed resin. used LiPF6 as the electrolyte and mixed EC and DEC, which are aprotic organic solvents, in a ratio of 3:7. The mixed solution was mixed at a volume ratio of 1. PP was used for the separator.

[0500] Next, the fabricated storage battery C was charged and discharged. The battery was charged at a constant current of 1.5 V (mA / g) with an upper limit of 4.6 V and discharged at a lower limit of 1.5 V. The discharge curve is shown in Figure 36. Here, the horizontal axis represents the capacity per weight of the positive electrode active material.

[0501] Use of superior materials with high capacity per unit weight for the positive and negative electrode active materials This made it possible to obtain a storage battery with a high capacity. [Example]

[0502] In this example, "particles containing lithium manganese composite oxide" of one embodiment of the present invention was used. In this example, a thin storage battery described in Embodiment 2 was manufactured. By providing a layer and a plurality of negative electrode active material layers and stacking them, a storage battery with a larger capacity can be manufactured. Ta.

[0503] <Preparation of positive electrode> A positive electrode active material for use in a storage battery was synthesized. First, steps S11 to S16 shown in Example 1 were performed. 14 steps were carried out.

[0504] (Step S15) Next, the bead mill was subjected to crushing treatment. The load was 0g, the peripheral speed was 12m / s, and the time was 10 hours.

[0505] (Step S16) Next, the crushed lithium manganese composite oxide was subjected to a heat treatment and dried. The specimen was heated on a hot plate at 75°C and then dried at 100°C under reduced pressure. The obtained lithium manganese composite oxide was placed in a crucible and fired. The firing was carried out at 800°C for 3 hours in a dry air atmosphere at a rate of 1 L / min. The powder was designated as sample A3.

[0506] (Step S17) Next, a carbon-containing layer was formed on the obtained sample A3. The solution was prepared by dividing the water into 1 / 3 portions and adding it to the graphene oxide using a kneader. The graphene oxide dispersion was prepared by mixing 10 g of graphene oxide with water. Next, sample A2 was added to 150 ml of the prepared dispersion solution. 500 g of the mixture was added to 200 mL of water, and the mixture was kneaded. The mixture was dried at 70°C in a ventilated oven, and then crushed in an alumina mortar to form graphite oxide. A lithium manganese composite oxide coated with silicon was obtained as sample B3.

[0507] (Step S18) Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the agent, and an 80% vol. ethanol aqueous solution was used as the solvent. The weight of the graphene oxide-coated lithium manganese composite oxide was The reducing solution was prepared by adding 16.87 wt% phosphoric acid and 3.9 wt% lithium hydroxide. The sample B3 was placed in a reducing solution and reduced at 60°C for 3 hours.

[0508] (Step S19) Next, the solvent was separated from the obtained solution using a centrifuge, and the separated liquid was discarded. The process of adding pure water to wash the mixture, centrifuging the mixture, and then discarding the separated liquid was repeated five times. The rotation speed of the separation was 2000 rpm to 6000 rpm, and the time was 3 minutes per separation. Pure water was added to the sample from which the catalyst was separated. The resulting solution was then heated to 150°C and sprayed. Dry processing was carried out.

[0509] Next, the powder obtained by spray drying was dried at 170°C under reduced pressure for 10 hours. did.

[0510] Through the above steps, a powder of lithium manganese composite oxide with graphene formed on the surface was obtained. (Sample C3) was prepared.

[0511] Next, sample C3 was used to fabricate a positive electrode for a storage battery. Acetylene black (AB) was used as an auxiliary agent, and PVdF was used as a binder. The active material, AB, and PVdF were mixed in the following ratio: active material:AB:PVdF=90:5:5 (wei ght%).

[0512] The active material, AB, PVdF, and NMP were mixed using a mixer to prepare a slurry. Next, a continuous coating machine was used to apply the coating to an undercoated aluminum foil with a thickness of 20 μm. The slurry was applied to the aluminum foil using a sieve. Next, the solvent was evaporated in a drying oven at 70°C for 10 minutes. After that, the solvent was evaporated at 90°C for 10 minutes.

[0513] Next, heat treatment was carried out in a reduced pressure atmosphere (1 kPa) at 250°C for 10 hours. The above steps were carried out to obtain the "lithium ion sintered body" according to one embodiment of the present invention. A positive electrode X3 having particles containing manganese composite oxide was obtained. The loading amount is 15.5 mg / cm per side. 2 It was.

[0514] Next, the prepared positive electrode X3 was charged and discharged using lithium metal as a counter electrode. used LiPF6 as the salt and polyethylene carbonate (PC) as the solvent. The discharge condition was set at a lower limit of 2V.

[0515] Thereafter, the positive electrode X3 was taken out from the electrolyte.

[0516] <Preparation of negative electrode> Next, a negative electrode for a storage battery was fabricated. SiO was used as the active material and A was used as the conductive additive. B used polyimide as a binder.

[0517] First, SiO:AB:polyimide precursor = 80:5:15 (weight%) SiO, AB, and the polyimide precursor were weighed as follows. A 13.7% solution using NMP as the solvent was used.

[0518] SiO, AB, polyimide precursor, and NMP were mixed to prepare a slurry. For the preparation of the slurry, refer to the process for preparing the negative electrode Y shown in Example 4.

[0519] Next, the slurry was applied to a rolled copper foil having a thickness of 18 μm using a continuous coating machine. The coating layer was applied to both sides of the copper foil. After that, it was dried in a drying oven. Heat treatment was carried out at 0°C for 180 seconds, and then at 75°C for 180 seconds. The amount of the active material carried on each side of the obtained negative electrode Y2 was 1.8. mg / cm 2 It was.

[0520] Next, the prepared negative electrode Y2 was charged using lithium metal as a counter electrode. The salt used was LiPF6, and the solvent was polyethylene carbonate (PC). Thereafter, the negative electrode Y2 was taken out from the electrolyte.

[0521] <Making a storage battery> Next, a storage battery C2, which is a thin storage battery according to the second embodiment, was fabricated. One positive electrode X3 with an active material layer on one side and two positive electrodes X3 with an active material layer on the other side were prepared. Furthermore, two negative electrodes Y2 each having an active material layer on both sides were prepared as negative electrodes.

[0522] The positive electrode X3, the negative electrode Y2, and the separator 507 are connected to the positive electrode active material layer 50 as shown in FIG. 2, and a positive electrode X3 having an aluminum foil as a positive electrode current collector 501, and a negative electrode active material layer 5 A separator 507 was placed between the negative electrode Y2 having a negative electrode Y5 and a copper foil as a negative electrode current collector 504. The plates were then laid out and stacked.

[0523] The exterior of the storage battery C2 was made of an aluminum film covered with a heat-sealed resin. The liquid used LiPF6 as the electrolyte, and EC, DEC, and ethyl methyl carbonate. The separator was a mixture of EMC and PEG in a weight ratio of 3:6:1. Polypropylene (PP) was used. In addition, VC (vinylene carbon dioxide) was added at a concentration of 1% or less. nate) and up to 1% propane sultone (PS) were added.

[0524] Next, the fabricated storage battery C2 was charged and discharged at 25°C and 0.1C (current density 1 The battery was charged at a constant current of 2 mA / g with an upper limit of 4.6 V and discharged at a lower limit of 1.5 V. The charge / discharge curve is shown in Figure 38(A). Here, the horizontal axis represents the capacity per weight of the positive electrode active material. In addition, Fig. 38(B) shows the weight of the positive electrode current collector and the negative electrode current collector calculated from the sum of the weights of the positive electrode and the negative electrode. The charge / discharge curve is shown with the normalized capacity on the horizontal axis, using the value obtained by subtracting the sum of the amounts.

[0525] Use of superior materials with high capacity per unit weight for the positive and negative electrode active materials This made it possible to obtain a storage battery with a high capacity. [Example]

[0526] In this example, the case where particles according to one embodiment of the present invention form secondary particles will be described.

[0527] First, steps S11 to S16 shown in FIG. 1 are carried out to obtain a lithium manganese composite oxide. For the processes of steps S11 to S16, refer to Example 1. The detailed conditions are described below.

[0528] In step S11, the starting materials are mixed in a weight ratio of Li2CO3:MnCO3:NiO= The mixture was weighed to give a ratio of 0.84:0.8062:0.318.

[0529] In step S12, the processing conditions of the bead mill are a peripheral speed of 10 m / s and a time of 30 minutes. Ta.

[0530] In step S13, drying is performed in the air at 75°C, and then the drying is performed under reduced pressure at 100°C. Drying took place in 1 hour.

[0531] In step S14, the firing conditions are 10 L / min, dry air atmosphere, 1000°C, It was set at 10 hours.

[0532] In step S15, the processing conditions of the bead mill are lithium manganese composite oxide 600 After that, it was dried at 75°C, and then heated to 100°C for 25 hours. Drying was carried out.

[0533] In step S16, the firing conditions are 10 L / min, dry air atmosphere, 800°C. The powder obtained in step S16 is designated as sample A4.

[0534] (Step S17) Next, a carbon-containing layer was formed on the obtained sample A4. The solution was prepared by dividing the water into 1 / 3 portions and adding it to the graphene oxide using a kneader. The mixture was kneaded to prepare a graphene oxide dispersion. The total amount of water added was 150 ml. Next, sample A4 and water were added to the prepared aqueous dispersion. The amount of sample A4 added was 500 g, and the amount of water was 200 ml. Next, the resulting mixture was dried at 70°C in a ventilated drying oven and then crushed in an alumina mortar. As a result, sample B4, which was a lithium manganese composite oxide coated with graphene oxide, was obtained.

[0535] (Step S18) Next, the graphene oxide in sample B4 was reduced. Acid was used, and an ethanol solution with a concentration of 80% by volume was used as the solvent. The weight of the coated lithium manganese composite oxide was 16.87 wt% ascorbic acid. 3.9 wt% of lithium hydroxide was added to prepare a reducing solution. The mixture was then reduced by treating at 60°C for 3 hours.

[0536] (Step S19) Next, the solvent was separated from the resulting solution using a centrifuge, and the separated liquid was discarded. After that, the mixture was washed with pure water, centrifuged, and the separated liquid was discarded. This process was repeated five times. The centrifugation was performed at 6000 rpm for 3 minutes. Pure water was added to the sample to obtain four solutions with different concentrations. The solutions with different concentrations are called solutions A and B. , C and D.

[0537] Solution A was prepared by adjusting the amount of pure water to 10 g / L relative to the amount of sample B4. Solution A is 100g / L, solution B is 300g / L, and solution D is 500g / L. After that, solutions A to D were heated to 60°C. The temperature was set to 150°C, and each solution was subjected to a spray drying treatment.

[0538] Next, each solution was spray-dried, and the resulting powder was dried at 170°C for 10 minutes. Each dried sample was dispersed in NMP to determine the particle size distribution. The particle size measured here is mainly the particle size of secondary particles. A laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation) was used for the measurement. The particle size was calculated using the laser diffraction and scattering method. diameter, and D90 (the value at which the cumulative particle amount reaches 90% in the cumulative particle amount curve of the particle size distribution measurement results) The particle size (particle size when it occupies 100% of the total particle size) was evaluated. Figure 4 shows a plot of particle size on the horizontal axis and frequency on the vertical axis. The results for the sample recovered from solution A are shown in solid line, solution B in dashed line, and solution C in dashed line. and solution D is shown by a two-dot chain line.

[0539] The average particle size of the sample collected from solution A was 3.26 μm, that of solution B was 2.45 μm, and that of solution C was 2.45 μm. was 3.84 μm, and solution A was 3.40 μm.

[0540] The D90 value of the sample recovered from solution A was 7.94 μm, and that of solution B was 9.73 μm. , solution C was 13.92 μm, and solution D was 13.18 μm.

[0541] The samples recovered from solutions C and D had large D90 values ​​of 13 μm or more, and the same values ​​as in Figure 4 As shown in 2, a tail is observed in the region above 20 μm.

[0542] Figure 43(A) shows solution A, (B) shows solution B, Figure 44(A) shows solution C, (B) shows solution D. The results of SEM observation of the obtained samples are shown below. In solutions B to D, the particle size was 15 μm. Secondary particles exceeding m were observed.

[0543] From the results of Figures 42 to 44, the concentration of the solution when performing the spray drying treatment is, for example, 10 It is believed that 0 g / L or less is preferable, and 10 g / L or less is more preferable. [Example]

[0544] In this example, gas release from a storage battery during charging and discharging was measured.

[0545] <Preparation of positive electrode> A positive electrode active material for use in a storage battery was synthesized in accordance with steps S11 to S15 shown in Example 6. I did 14.

[0546] (Step S15) Next, the bead mill was subjected to crushing treatment. After processing 0g at a peripheral speed of 8m / s for 20 minutes, it was processed at 12m / s for 10 hours. Drying was carried out.

[0547] (Step S16) Next, the mixture was fired under the conditions of 10 L / min, dry air atmosphere, 800°C, 3 The powder obtained in step S16 is designated as sample A5.

[0548] (Step S17) Next, a carbon-containing layer was formed on the obtained sample A5. First, water and graphene oxide were mixed. The graphene oxide was mixed to prepare an aqueous dispersion of the graphene oxide. Next, 100 g of sample A5 and 20 ml of water were added to the prepared aqueous dispersion. L was added and the mixture was kneaded. Next, the resulting mixture was dried and then crushed in an alumina mortar. As a result, sample B5, which is a lithium manganese composite oxide coated with graphene oxide, was obtained.

[0549] (Step S18) Next, the graphene oxide containing sample B5 was reduced. As a reducing agent, ascorbic acid was used. The acid was used, and a mixed solvent of ethanol and water was used as the solvent. The concentration of the graphene oxide was 80% by volume. The weight of the solution contains 16.87 wt% ascorbic acid and 3.9 wt% lithium hydroxide. The resulting sample B5 was placed in the reducing solution and treated at 60°C for 3 hours to reduce it. It's back.

[0550] (Step S19) Next, the obtained solution was filtered to separate the solvent and obtain a sample. After that, it was dried and named Sample C. I got a 5.

[0551] The obtained sample C5 was used to prepare a positive electrode. Acetylene black (AB) was used as the active material, and PVdF was used as the binder. The blending ratio of AB, PVdF and active material was 90:5:5 (weight ratio). %) and NMP as a solvent to prepare a slurry.

[0552] Next, the prepared slurry was applied to an undercoated aluminum plate with a thickness of 20 μm. The foil was coated on one side, then heated to evaporate the solvent, and then pressed. Then, heat treatment was carried out at 250°C for 10 hours under a pressure of 1 kPa.

[0553] The positive electrode obtained by the above steps is referred to as positive electrode X4. The amount of active material carried in positive electrode X4 is 6.5 mg / cm 2 It was.

[0554] <Preparation of negative electrode> Next, a negative electrode was fabricated using graphite as the active material. The graphite, carbon fiber, CMC, and water were mixed in a mixer to prepare a slurry. The ratio of SBR is graphite:carbon fiber:CMC:SBR=96:1:1:2 (weight%) It was decided.

[0555] Next, the prepared slurry was applied to one side of a rolled copper foil with a thickness of 18 μm. The negative electrode obtained was designated as negative electrode Y3. The material loading is 8.8 mg / cm 2 It was.

[0556] <Preparation of reference electrode> Next, a positive electrode using LiFePO4 as the active material was prepared as a comparison electrode. Aluminum foil was used. The prepared positive electrode is designated as positive electrode X5. The amount of active material carried in positive electrode X5 was 1 0.8 mg / cm 2 It was.

[0557] <Preparation of negative electrode> Next, a negative electrode was fabricated using graphite as the active material. The graphite, carbon fiber, CMC, and water were mixed in a mixer to prepare a slurry. The ratio of SBR is graphite:carbon fiber:CMC:SBR=96:1:1:2 (weight%) Next, the prepared slurry was applied to one side of a rolled copper foil with a thickness of 18 μm. The resulting negative electrode was designated as negative electrode Y4. The amount of active material carried in the 2 It was.

[0558] <Making a storage battery> Next, a storage battery C3 was fabricated using six of the fabricated positive electrodes X4 and six of the fabricated negative electrodes Y3. A storage battery C4 was fabricated using six positive electrodes X5 and six negative electrodes Y4, which were comparative electrodes.

[0559] The exterior of storage battery C3 and storage battery C4 is made of aluminum film covered with heat-sealed resin. The electrolyte used was LiPF6, and the solvent was EC:DEC:EM. C in a volume ratio of 3:6:1. In addition, PP was used for the separator.

[0560] The positive electrode, negative electrode and separator consist of six pairs of positive electrode active material layers and negative electrode active material layers, and six pairs of separators. The sheets were stacked facing each other with an intervening gap.

[0561] Next, the fabricated storage battery C3 was charged and discharged at 25°C at 0.1 C (current density 1 7mA / g), and then charge at a constant current of 4.6V, followed by 0.01C at a constant voltage of 4.6V. The final condition was charging. Then, constant current discharge was performed at the lower limit of 2.0 V. The discharge capacity was The positive electrode active material was 207 mAh / g. , a high capacity was obtained.

[0562] The battery C4 was also charged and discharged at 25°C and 0.01C (current density 24mA / g), and then constant current charging at 3.2V, and then constant current charging at 0.1C, and maximum 4V. Then, constant current discharge was performed at 0.2C, lower limit 2.0V. After constant current charging with an upper limit of 4V, constant current discharging was performed with a lower limit of 2V at 0.2C. For both batteries C3 and C4, the current density and capacity were normalized per weight of the positive electrode active material. The first discharge capacity was 109 mAh / g, and the second discharge capacity was 123 mAh / g.

[0563] Next, gas samples were collected from the storage batteries C3 and C4 after charging and discharging.

[0564] Next, each of the collected gases was analyzed by GC-TCD (Gas Chromatography). Measured using a y-Thermal Conductivity Detector The types and abundance ratios of the gases obtained are shown in Table 4. In Table 4, H2, O2, N2, C The total abundance ratio of eight gases, O, CH4, CO2, C2H4, and C2H6, is 100 Here, for gases without numerical values, it means that the gas is below the detection limit or This shows a case where CO2 was detected but in a small amount and difficult to quantify. However, it was only a small amount.

[0565] [Table 4]

[0566] From Table 4, the CO2 value was very small for battery C4, which used LiFePO4 for the positive electrode. In contrast, in battery C3, which uses sample C5 for the positive electrode, CO2 accounts for a high percentage of the eight gases, at 30%. In addition, 45% hydrogen was detected in storage battery C3 and 64% in storage battery C4. The total amount of gas generated was greater for battery C3.

[0567] The storage battery C3 has a high charge and discharge potential, which increases the energy density of the storage battery. On the other hand, when the charge and discharge potentials are high, the electrolyte is oxidized. Decomposition may occur easily. The upper limit of the charging voltage for battery C3 is high at 4.6V. It is believed that the electrolyte decomposed during the charging process, which made it easy for gases such as CO2 to be generated. Therefore, when the particles according to one embodiment of the present invention are used as a positive electrode active material, the particles according to Example 4 and Example 5 As shown in the figure, this occurs when the battery is opened after charging and discharging the positive electrode of the battery. By releasing the gas and then reassembling the battery, the battery can be recharged due to gas generation. This is preferable because it can reduce the influence on the characteristics of the semiconductor device. [Example]

[0568] In this example, we investigated the effects of graphene oxide coating and treatment with a reducing solution on the characteristics of the storage battery. We investigated the possible impact.

[0569] First, particles containing lithium manganese composite oxide were prepared. Steps S11 to S14 were carried out.

[0570] (Step S15) Next, the bead mill was subjected to crushing treatment. After processing 0g at a peripheral speed of 8m / s for 10 minutes, it was processed at 4m / s for 10 hours. The powder obtained here is designated as Sample A6.

[0571] Next, the sample A6 was treated with a reducing solution (sample B6), and the oxidation graph The conditions for coating graphene oxide and performing reduction treatment (sample C6) were as follows: D6), each sample was prepared.

[0572] (Step S17) A carbon-containing layer was formed on sample A6. First, water and graphene oxide were mixed, and the graphene oxide was A graphene oxide dispersion solution was prepared. 0.3 g of graphene oxide was added to a total of 3 mL of water. Next, 15 g of sample A6 and 3 mL of water were added to the prepared aqueous dispersion solution, and the mixture was kneaded. Next, the obtained mixture was dried and then crushed in an alumina mortar to obtain sample C6.

[0573] (Steps S18 and S19) Next, Samples C6 and A6 were treated with a solution of ascorbic acid. A mixed solvent of ethanol and water was used as the solvent. The amount of ascorbic acid was 80% by volume. A reducing solution was prepared by adding 7 wt% of ammonium hydroxide and about 4 wt% of lithium hydroxide.

[0574] Sample C6 was placed in the reducing solution and treated at 60°C for 3 hours. After that, the solution was filtered and dried. Sample D6 was obtained by this procedure. Sample A6 was also placed in a reducing solution and treated at 60°C for 3 hours. Thereafter, the solution was filtered and dried to obtain sample B6.

[0575] <Preparation of electrodes> Electrodes were fabricated using the obtained samples A6, B6, C6, and D6 as active materials. Acetylene black (AB) was used as a conductive additive, and PVD was used as a binder. The active material, AB, and PVdF were mixed in a ratio of active material:AB:PVdF=90:5. :5 (weight %) and NMP was used as a solvent to prepare a slurry.

[0576] Next, the prepared slurry was applied to an undercoated aluminum plate with a thickness of 20 μm. The foil was coated on one side, then dried, pressed, and then heat-treated. The heat treatment conditions were a pressure of 1 kPa, 250°C, and 10 hours.

[0577] The electrodes obtained using Samples A6, B6, C6, and D6 are referred to as Electrode A, respectively. 6, electrode B6, electrode C6 and electrode D6. Electrode A6, electrode B6, electrode C6 and The active material loading of electrode D6 was 3.2 mg / cm 2 , 4.1 mg / cm 2 , 3.0 mg / cm 2 and 3.7 mg / cm 2 It was.

[0578] <Half-cell characteristics> Next, half cells were fabricated using the resulting electrodes A6, B6, C6, and D6. A coin cell was used for the electrolytic cell. Lithium was used as the counter electrode for the half cell. The liquid used LiPF6 as the electrolyte and aprotic organic solvents EC and DEC in a 1:1 ratio. The mixed solution was mixed at a volume ratio of 1. The separator was made of polypropylene ( PP) was used.

[0579] Next, the charge-discharge cycle of the fabricated half-cell was evaluated. The upper limit voltage was 4.8V, and the discharge was performed at a constant current of 0.1C and a lower limit voltage of 2V. The graph shows the number of charge / discharge cycles plotted on the horizontal axis and the discharge capacity plotted on the vertical axis.

[0580] Electrode A6 without graphene oxide coating and treatment with ascorbic acid solution In the case of the ascorbic acid solution, a significant decrease in capacity was observed from the third cycle onwards. The electrode B6, which was treated with this method, was able to suppress the capacity decrease, and the capacity at the 10th cycle was The graphene oxide-coated electrode C6 achieved a capacity of 10 s. The final capacity was more than 90% of the initial capacity, further suppressing capacity loss. For electrode D6, which was coated with ZnO and then reduced in a reducing solution, the capacity at the 10th cycle was The highest value of 98% of the initial capacity was obtained.

[0581] From the above, when the particles of one embodiment of the present invention are treated with an ascorbic acid solution, For example, a more stable region may be formed on at least a portion of the surface of the particle compared to the interior. In addition, the coating layer having graphene oxide or reduced graphene can be The covered regions are more stable than the inner regions of the particles, improving the charge / discharge stability of the battery. This suggests that this was the case. [Example]

[0582] In this example, "particles containing lithium manganese composite oxide" according to one embodiment of the present invention were prepared. The fabrication procedure is explained based on the flowchart in Figure 1.

[0583] <Synthesis> First, particles containing lithium manganese composite oxide were prepared.

[0584] (Step S11) First, Li2CO3, MnCO3, and NiO were used as starting materials. The molar ratio of Li2CO3:MnCO3:NiO is 0.84:0.8062:0 It weighed out to 0.318.

[0585] (Step S12) Next, ethanol was added to the starting materials, and then the mixture was mixed using a bead mill. The peripheral speed of the treatment chamber was set to 10 m / s.

[0586] (Step S13) Next, the mixed raw materials were subjected to a heat treatment. The heat treatment was carried out in an air atmosphere at a heating temperature of 1000 K. By carrying out the process at a temperature of 75°C, the ethanol contained in the mixed raw materials is evaporated, and the mixture is A composite material was obtained.

[0587] (Step S14) Next, the mixed raw materials were placed in a crucible and fired. The firing process was carried out in a dry oven with a flow rate of 10 L / min. By firing in an air atmosphere at 1000°C for 10 hours, Lithium manganese composite oxide was synthesized.

[0588] (Step S15) Next, a crushing process is carried out to remove the sintering of the lithium manganese composite oxide, which has sintered primary particles. The crushing process was carried out by adding ethanol to the sintered lithium manganese composite oxide. The processing chamber of the zeal mill was rotated at a peripheral speed of 8 m / s for 10 minutes, and then rotated at 4 m / s for 10 hours. After the treatment, a powdery lithium manganese composite oxide was obtained.

[0589] (Step S16) Next, the crushed lithium manganese composite oxide was subjected to a heat treatment. By carrying out the process at 75°C under an air atmosphere, the ethanol contained in the mixed raw materials is The resulting lithium manganese composite oxide was then placed in a crucible and fired. The firing conditions were 700°C for 3 hours in a dry air atmosphere at 10 L / min. After firing, the resulting powder was designated as Sample A. Sample A had the composition formula Li 1.68 Mn 0.806 2Ni 0.318 It is expressed as O3, but the composition may deviate from this.

[0590] <Coating layer> Next, a carbon-containing layer was formed on the obtained sample A. First, 0.1 g of graphene oxide was The graphene oxide dispersion solution was prepared by mixing the graphene oxide with water in a ratio of 1g to 1g. It was made.

[0591] (Step S17) Next, sample A was added to the prepared aqueous dispersion and mixed. The mixture was mixed in a bell jar so that 50g of sample A was mixed with 1g of the mixture. After drying under reduced pressure at 50°C, the graphene oxide-coated lithium ion was crushed in an alumina mortar. A manganese-manganese composite oxide, sample B, was obtained.

[0592] (Step S18) Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the agent, and a mixed solvent of ethanol and water was used as the solvent. The concentration of ethanol in the solvent was 80% by volume. The weight of the manganese-ascorbic acid composite oxide was 16.87 wt% and the weight of the lithium hydroxide The resulting powder was added to the reducing solution and heated to 60°C. The mixture was reduced by treating with HCl for 3 hours.

[0593] (Step S19) Next, the resulting solution was filtered by suction. Filter paper was used, then washed and filtered again.

[0594] Next, pure water was added to the sample from which the solvent had been separated to adjust the concentration to 15 g / L. The resulting solution was then heated to 60°C and fed to a spray dryer. The mixture was heated to 0°C and spray-dried.

[0595] Next, the powder obtained by spray drying was dried under reduced pressure at 170°C for 10 hours. did.

[0596] Next, the obtained powder was crushed in a mortar and then dried at 170°C under reduced pressure for 10 hours. went.

[0597] Through the above steps, a powder of lithium manganese composite oxide with graphene formed on the surface was obtained. (Sample C) was prepared.

[0598] <Preparation of electrodes> Next, an electrode was fabricated using the obtained sample C. Sample C was used as the active material, and the conductive additive Acetylene black (AB) was used as the carrier and PVdF was used as the binder.

[0599] First, PVdF, AB, and a polar solvent, NMP (N-methyl-2-pyrrolidone), were mixed. The mixture was kneaded using a kneader to obtain a slurry. The electrode mixture composition was blended in a weight ratio of Sample C:A. The B:PVdF ratio was 90:5:5.

[0600] Next, the electrode mixture composition was applied onto an aluminum foil as a current collector. The aluminum foil surface was first coated with an undercoat. After that, it was dried in a ventilated oven at 80°C. The electrode thus obtained was designated electrode X1. The electrode was pressed so that the film thickness was reduced by 20% compared to the film thickness after electrode coating. The pressing temperature was set to 120°C.

[0601] Thereafter, the electrode X1 was subjected to a heat treatment. The heat treatment conditions were a reduced pressure atmosphere (1 kPa), The treatment was carried out for 10 hours at 50° C. Through the above steps, an electrode X2 was obtained.

[0602] <Half-cell characteristics> Next, a half cell was fabricated using the obtained electrodes X1 and X2. The counter electrode of the half cell was lithium. LiPF6 was used as the substrate, and aprotic organic solvents EC and DEC were mixed in a volume ratio of 1:1. The mixed solution was prepared by mixing the above materials. Polypropylene (PP) was used as the separator. there was.

[0603] Next, the charge-discharge characteristics were measured at 25°C. The discharge was carried out at a constant current of 30 mA / g and a lower limit voltage of 2 V. The charge / discharge curves are shown in Figure 52. The dashed line shows the charge / discharge curve for electrode X1, and the solid line shows the charge / discharge curve for electrode X2. It was found that electrode X2, which was heat-treated, had a higher capacity. It was. [Example]

[0604] In this example, the results of XPS analysis of an electrode of one embodiment of the present invention will be described.

[0605] <Synthesis> First, particles containing lithium manganese composite oxide were prepared according to the steps shown in Figure 1. did.

[0606] (Step S11) First, Li2CO3, MnCO3, and NiO were used as starting materials. The molar ratio of Li2CO3:MnCO3:NiO is 0.84:0.8062:0 It weighed out to 0.318.

[0607] (Step S12) Next, ethanol was added to the starting materials, and then the mixture was mixed using a bead mill. The peripheral speed of the treatment chamber was set to 10 m / s.

[0608] (Step S13) Next, a heat treatment was carried out at 100°C or less to evaporate the ethanol, and a mixed raw material was obtained.

[0609] (Step S14) Next, the mixed raw materials were placed in a crucible and fired. The firing process was carried out in a dry oven with a flow rate of 10 L / min. The firing temperature was 1000°C and the firing time was 10 hours in an air atmosphere.

[0610] (Step S15) Next, the lithium manganese composite oxide in which the primary particles were sintered was subjected to a crushing treatment. After adding ethanol to 600 g of sintered lithium manganese composite oxide, The treatment was carried out for 10 hours at a peripheral speed of 12 m / s in the treatment chamber of the granular mill.

[0611] (Step S16) Next, the mixture was heated at 100°C or less to evaporate the ethanol. The manganese oxide composite was placed in a crucible and fired. The firing conditions were a dry flow rate of 10 L / min. The powder was calcined at 800°C for 3 hours in a dry air atmosphere. Sample A2 has the composition formula Li 1.68 Mn 0.8062 Ni 0.318 It is represented by O3 However, the composition may deviate from this.

[0612] <Coating layer> Next, a carbon-containing layer was formed on the surface of the obtained sample A2. The mixture was kneaded in a kneader at a ratio of 1 g to 15 mL of water to obtain graphene oxide. A dispersion solution was prepared.

[0613] (Step S17) Next, sample A2 was added to the prepared aqueous dispersion and mixed. The mixture was mixed in a bell jar so that 50 g of sample A2 was mixed with 1 g of ethanol. After drying under reduced pressure at 70°C, the graphene oxide-coated lithograph was crushed in an alumina mortar. A lithium manganese composite oxide, sample B2, was obtained.

[0614] (Step S18) Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the agent, and a mixed solvent of ethanol and water was used as the solvent. The concentration of ethanol in the solvent was 80% by volume. Ascorbic acid is 16.87 weight percent of the weight of manganese oxide. 3.9 wt% of lithium hydroxide was added to prepare a reducing solution. The mixture was placed in a solution and treated at 60°C for 3 hours to reduce the mixture.

[0615] (Step S19) Next, the obtained solution was centrifuged to separate the solvent and the sample. Next, pure water was added to the sample from which the solvent had been separated to adjust the concentration to 24 g / L. The resulting solution was then heated at 60°C and then passed through the supply port of a spray dryer. The mixture was heated to 00°C and spray-dried.

[0616] Next, the powder obtained by spray drying was dried under reduced pressure at 170°C for 10 hours. did.

[0617] Through the above steps, a powder of lithium manganese composite oxide with graphene formed on the surface was obtained. (Sample C2) was prepared.

[0618] <Preparation of electrodes> Next, electrodes were fabricated using the obtained sample C2. Sample C2 was used as the active material, acetylene black (AB) was used as the conductive aid, and PVdF was used as the binder.

[0619] First, PVdF, AB, and the polar solvent NMP (N-methyl-2-pyrrolidone) were kneaded using a kneader to obtain a slurry. The formulation of the electrode mixture composition was such that the weight ratio of sample C:A B:PVdF was 90:5:5.

[0620] Next, the electrode mixture composition was applied onto an aluminum foil, which was the current collector. An undercoat was applied in advance to the surface of the aluminum foil. Thereafter, it was dried at 80 °C for 30 minutes in a ventilation drying oven. The electrode thus obtained was designated as electrode X3. Next, the electrode X3 was pressed using a roll press machine. The pressing pressure was adjusted so as to reduce the film thickness by 20% with respect to the film thickness after electrode coating was performed. Also, the pressing temperature was set at 120 °C.

[0621] Thereafter, heat treatment was performed on electrode X3. The electrode obtained by performing heat treatment on electrode X3 at 1 kPa, 170 °C for 10 hours was designated as electrode X4. Also, the electrode obtained by performing heat treatment on electrode X3 at 1 kPa, 250 °C for 10 hours was designated as electrode X5.

[0622] <XPS analysis> XPS analysis was performed on the obtained electrodes X3, X4, and X5. The narrow spectra of Li1s, O1s, C1s and F1s are shown in Figs. 53(A), (B), Fig. 54(A), and (B). Also, the abundance ratios of Ni, Mn, Li, O, C, and F are shown in Table 5. In Table 5, the numerical values were normalized such that the sum of the abundance ratios of the six elements became 100 atomic%. The sum of the abundance ratios of the six elements was normalized so as to be 100 atomic%.

[0623] [Table 5]

[0624] From Figure 53(A), the intensity of the peaks due to LiF, etc., is higher for electrode X5 than for X3 and X4. From Figure 54(A), it can be seen that the heat treatment of the electrodes X3, X4, and X5 further increased the As the heat treatment temperature increases, the number of CF2 and O-CF bonds decreases. 3. X4, X5 and the heat treatment of the electrode, and by increasing the temperature of the heat treatment, the metal-F bond From the above, it is thought that the heat treatment of the electrode and the increase in temperature will cause the The contained CF2 and O-CF bonds are broken, and the Li of sample C and the CF2 and O-CF bonds It is thought that Li-F bonds were formed between the F atoms that were generated by the bond breaking. It is possible that the strength of the electrode was improved by the formation of [Example]

[0625] In this example, a half cell was fabricated using an electrode according to one embodiment of the present invention, and its characteristics were evaluated. Ta.

[0626] <Preparation of electrodes> An electrode was fabricated using Sample C2 obtained using the process shown in Example 2. Sample C2 was used, and acetylene black (AB) was used as the conductive additive and Polyimide was used.

[0627] First, a polyimide (PI) precursor, AB, and a polar solvent, NMP (N-methyl-2 -pyrrolidone) was kneaded using a kneader to obtain a slurry. The weight ratio of sample C:AB:PI was 90:5:5. An MP solution was used, with a concentration of 13.7% by weight.

[0628] Next, the electrode mixture composition was applied onto an aluminum foil as a current collector. The aluminum foil surface was first coated with an undercoat. After that, it was dried in a drying oven at 80°C for 30 minutes. The electrode obtained here is called electrode Z1. Press was conducted.

[0629] Thereafter, the electrode Z1 was subjected to a heat treatment at 1 kPa and 300°C for 10 hours. Let the pole be Z2.

[0630] <Half-cell characteristics> Next, a half-cell was fabricated using electrode Z2. The same conditions as in Example 1 were used.

[0631] Next, the charge-discharge characteristics were measured at 25°C. The discharge was carried out at a constant current of 30 mA / g and a lower limit voltage of 2 V. The charge-discharge curves are shown in Figure 55. Electrode Z2 was heat-treated at a high temperature of 300°C. It was found that a very high discharge capacity of 281 mAh / g was obtained. [Explanation of symbols]

[0632] 100 electrodes 101 Current collector 102 Active material layer 120a graphene 131 areas 132 areas 133 areas 141 particles 142 areas 143 areas 300 storage battery 301 Positive electrode can 302 Anode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior body 510 Positive lead electrode 511 Negative lead electrode 512 Welding Area 513 Curved section 514 Sealing part 600 storage battery 601 Positive electrode cap 602 Battery can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating board 611 PTC element 612 Safety valve mechanism 900 Circuit Board 910 Label 911 terminal 912 circuits 913 Storage battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 terminal 920 Display device 921 Sensor 922 terminal 951 terminal 952 terminals 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 1805 Electrodes, electrolytes, etc. 7100 Portable display devices 7101 Housing 7102 Display section 7103 Operation button 7104 Energy storage devices 7200 Personal Digital Assistant 7201 Case 7202 Display section 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 display device 7304 Display section 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Electricity storage devices 7408 Lead electrode 7409 Current collector 8000 display device 8001 Case 8002 Display section 8003 Speaker section 8004 Electricity storage devices 8021 Charging device 8022 cable 8024 Electricity storage device 8100 Lighting equipment 8101 Housing 8102 Light source 8103 Energy storage devices 8104 Ceiling 8105 Side wall 8106 beds 8107 Window 8200 indoor unit 8201 Housing 8202 Ventilation outlet 8203 Energy storage devices 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Housing 8302 Refrigerator door 8303 Freezer door 8304 Energy storage devices 8400 Automobiles 8401 Headlight 8406 Motor 8500 cars 9600 tablet device 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fasteners 9630 chassis 9630a housing 9630b housing 9631 Display section 9631a Display section 9631b Display section 9632a area 9632b area 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Electricity storage unit 9636 DC / DC Converter 9637 Converter 9638 Operation key 9639 Button 9640 Moving parts S1 control signal S2 control signal S3 transformer signal BT00 Power storage device BT01 terminal pair BT02 terminal pair BT03 Switching control circuit BT04 switching circuit BT05 switching circuit BT06 Transformer control circuit BT07 transformer circuit BT08 battery part BT09 Battery Cell BT10 transistor BT11 Bus BT12 Bus BT13 transistor BT14 Current Control Switch BT15 Bus BT16 Bus BT17 Switch vs. BT18 Switch vs. BT21 Transistor Pair BT22 transistor BT23 transistor BT24 Bus BT25 Bus BT31 Transistor Pair BT32 transistor BT33 transistor BT34 Bus BT35 Bus BT41 Battery Control Unit BT51 Isolated DC-DC Converter BT52 switch part BT53 transformer

Claims

1. A lithium ion secondary battery having a positive electrode, the positive electrode has a current collector and an active material layer on the current collector, the active material layer includes a composite oxide containing lithium and manganese, and graphene covering at least a portion of the composite oxide; the composite oxide has a first region and a second region, the second region is located closer to the surface than the first region and in a surface layer portion of the complex oxide, the first region and the second region contain lithium and oxygen; the first region and the second region contain manganese and an element represented by M, The element represented by M is a metal element selected from Ni, Ga, Fe, Mo, In, Nb, Nd, Co, Sm, Mg, Al, Ti, Cu, or Zn, Si, or P, the first region has first crystals that have a layered rock salt structure; the second region has second crystals that have a layered rock salt structure; an orientation of the first crystal is different from an orientation of the second crystal; a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the second region is smaller than a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the first region; The lithium ion secondary battery, wherein the graphene includes multi-layer graphene.

2. A lithium ion secondary battery having a positive electrode, the positive electrode has a current collector and an active material layer on the current collector, the active material layer includes a composite oxide containing lithium and manganese, and graphene covering at least a portion of a surface of the composite oxide; the composite oxide has a first region and a second region, the second region is located closer to the surface than the first region and in a surface layer portion of the complex oxide, the first region and the second region contain lithium and oxygen; the first region and the second region contain manganese and an element represented by M, The element represented by M is a metal element selected from Ni, Ga, Fe, Mo, In, Nb, Nd, Co, Sm, Mg, Al, Ti, Cu, or Zn, Si, or P, the first region has first crystals that have a layered rock salt structure; the second region has second crystals that have a layered rock salt structure; an orientation of the first crystal is different from an orientation of the second crystal; a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the second region is smaller than a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the first region; The lithium ion secondary battery, wherein the graphene includes multi-layer graphene.

3. A lithium ion secondary battery having a positive electrode, the positive electrode has a current collector and an active material layer on the current collector, the active material layer includes a composite oxide containing lithium and manganese, and graphene covering at least a portion of a cleavage plane of the composite oxide; the composite oxide has a first region and a second region, the second region is located closer to the surface than the first region and in a surface layer portion of the complex oxide, the first region and the second region contain lithium and oxygen; the first region and the second region contain manganese and an element represented by M, The element represented by M is a metal element selected from Ni, Ga, Fe, Mo, In, Nb, Nd, Co, Sm, Mg, Al, Ti, Cu, or Zn, Si, or P, the first region has first crystals that have a layered rock salt structure; the second region has second crystals that have a layered rock salt structure; an orientation of the first crystal is different from an orientation of the second crystal; a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the second region is smaller than a ratio of the number of oxygen atoms to the sum of the numbers of manganese and the element represented by M in the first region; The lithium ion secondary battery, wherein the graphene includes multi-layer graphene.

4. In any one of claims 1 to 3, The graphene contains oxygen, and a ratio of oxygen contained in the graphene is equal to or greater than 2 atomic % and equal to or less than 20 atomic %.

5. In any one of claims 1 to 4, The lithium ion secondary battery, wherein the second region has a thickness of 0.1 nm or more and 30 nm or less.

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