Positive electrode for nonaqueous electrolyte energy storage device, and nonaqueous electrolyte energy storage device

Abstract

To provide a positive electrode for a nonaqueous electrolyte power storage element having a large discharge capacity density and capable of enhancing initial Coulomb efficiency of the nonaqueous electrolyte power storage element and discharge capacity during high-rate discharge, and to provide a nonaqueous electrolyte power storage element including such a positive electrode.SOLUTION: A positive electrode for a nonaqueous electrolyte energy storage device according to one aspect of the present invention includes a positive electrode active material layer, wherein the positive electrode active material layer contains a positive electrode active material, a solid electrolyte, and a binder, and contains substantially no conductive agent, and the positive electrode active material layer has a thickness of 80 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a positive electrode for a non-aqueous electrolyte storage element and a non-aqueous electrolyte storage element. [Background technology]

[0002] Due to their high energy density, non-aqueous electrolyte secondary batteries, such as lithium ion secondary batteries, are widely used in electronic devices such as personal computers and communication terminals, as well as in automobiles. Non-aqueous electrolyte secondary batteries generally have a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and are configured to charge and discharge by transferring charge-transporting ions such as lithium ions between the electrodes. Other non-aqueous electrolyte energy storage elements besides non-aqueous electrolyte secondary batteries include capacitors such as lithium ion capacitors and electric double layer capacitors.

[0003] A positive electrode for an electricity storage element may have a positive electrode mixture layer (positive electrode active material layer) containing a positive electrode active material and a solid electrolyte (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2018-085310 Summary of the Invention [Problem to be solved by the invention]

[0005] Increasing the thickness of the positive electrode active material layer containing a solid electrolyte to increase the discharge capacity density tends to reduce the discharge capacity during high-rate discharge of the nonaqueous electrolyte energy storage element, and also tends to reduce the coulombic efficiency at the beginning of the charge-discharge cycle of the nonaqueous electrolyte energy storage element.

[0006] An object of the present invention is to provide a positive electrode for a nonaqueous electrolyte energy storage element that has a high discharge capacity density and can increase the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte energy storage element, and a nonaqueous electrolyte energy storage element including such a positive electrode. [Means for solving the problem]

[0007] A positive electrode for a non-aqueous electrolyte storage element according to one aspect of the present invention has a positive electrode active material layer, the positive electrode active material layer containing a positive electrode active material, a solid electrolyte, and a binder, and substantially free of a conductive agent, and the positive electrode active material layer having a thickness of 80 μm or more.

[0008] A positive electrode for a non-aqueous electrolyte storage element according to another aspect of the present invention has a positive electrode active material layer, the positive electrode active material layer containing a positive electrode active material, a solid electrolyte, and a binder, and substantially not containing a conductive agent, and the positive electrode active material layer has a discharge capacity density per area of ​​4 mAh / cm 2 That's all.

[0009] A nonaqueous electrolyte storage element according to another aspect of the present invention includes a positive electrode for the nonaqueous electrolyte storage element according to any one of the aspects of the present invention. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to provide a positive electrode for a nonaqueous electrolyte energy storage element that has a high discharge capacity density and can increase the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte energy storage element, and a nonaqueous electrolyte energy storage element including such a positive electrode. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an all-solid-state electricity storage element, which is a nonaqueous electrolyte electricity storage element according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an electricity storage device formed by assembling a plurality of nonaqueous electrolyte electricity storage elements. DETAILED DESCRIPTION OF THE INVENTION

[0012] First, an outline of the positive electrode for a nonaqueous electrolyte storage element and the nonaqueous electrolyte storage element disclosed in this specification will be described.

[0013] [1] A positive electrode for a non-aqueous electrolyte storage element according to one aspect of the present invention has a positive electrode active material layer, the positive electrode active material layer containing a positive electrode active material, a solid electrolyte, and a binder, and being substantially free of a conductive agent, and the positive electrode active material layer having a thickness of 80 μm or more.

[0014] The positive electrode for a nonaqueous electrolyte storage element described in [1] above has a large discharge capacity density and can increase the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element. Although the reason for this is unclear, the following reason is presumed. Generally, when a positive electrode having a thick positive electrode active material layer containing a solid electrolyte is used, the discharge capacity during high-rate discharge of a nonaqueous electrolyte storage element is likely to decrease. The initial Coulombic efficiency of the nonaqueous electrolyte storage element is also likely to decrease. The initial Coulombic efficiency and high-rate discharge capacity are likely to decrease because the transfer rate of charge-transporting ions or electrons in the positive electrode active material layer is likely to be insufficient in the thickness direction of the positive electrode active material layer, which makes the reaction more likely to proceed unevenly in the thickness direction during charge and discharge. In other words, the initial Coulombic efficiency and high-rate discharge capacity are thought to decrease due to variations in the utilization rate of the positive electrode active material. To promote electron transfer in the positive electrode active material layer, a conductive agent is typically incorporated into the positive electrode active material layer. In contrast, the positive electrode for a nonaqueous electrolyte storage element described in [1] above has a positive electrode active material layer with a thickness of 80 μm or more, and even when it contains typical voids, the discharge capacity density per area of ​​the positive electrode active material layer is high. Furthermore, because the positive electrode active material layer is substantially free of a conductive agent, the content of the solid electrolyte can be increased while maintaining a certain level of the positive electrode active material content in the positive electrode active material layer, thereby promoting the migration of charge-transporting ions in the positive electrode active material layer. The movement of electrons in the positive electrode active material layer can be ensured by the positive electrode active material. That is, the ionic conductivity of the positive electrode active material layer can be increased while maintaining a sufficiently high level of electronic conductivity. Furthermore, because the thickness of the positive electrode active material layer is within the above range, ionic conduction in the positive electrode active material layer is likely to be the rate-limiting step in the charge-discharge reaction. By promoting the migration of charge-transporting ions, the charge-discharge reaction can proceed more uniformly. For these reasons, it is presumed that the positive electrode for a nonaqueous electrolyte storage element described in [1] above has a high discharge capacity density and can increase the initial Coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0015] In the present invention, "substantially free of conductive agent" means that the content of conductive agent in the positive electrode active material layer is 0.1 mass % or less.

[0016] In the present invention, the "thickness of the positive electrode active material layer" refers to the average thickness of one or more positive electrode active material layers. That is, for example, when one positive electrode active material layer is provided on each side of the positive electrode substrate, the "thickness of the positive electrode active material layer" refers to the average thickness of one positive electrode active material layer on each side. The "average thickness" refers to the average value of thicknesses measured at any five positions, and the same applies to the following description of the present specification.

[0017] In the present invention, the thickness of the positive electrode active material layer is measured on a cross section of the positive electrode cut in the thickness direction of the positive electrode active material layer. The cross section of the positive electrode is prepared by exposing the cross section using ion milling. The prepared cross section is observed using a scanning electron microscope to measure the thickness. If a positive electrode can be prepared before assembling a nonaqueous electrolyte storage element, it is used as is. When preparing a positive electrode from an assembled nonaqueous electrolyte storage element, it is prepared using the following procedure. First, the nonaqueous electrolyte storage element is discharged at a constant current of 0.05 C to the lower limit voltage for normal use. Next, the nonaqueous electrolyte storage element is disassembled and the electrode body is removed. A cross section of the electrode body is prepared using ion milling, and the thickness of the layer believed to be the positive electrode active material layer is measured using a scanning electron microscope.

[0018] [2] A positive electrode for a nonaqueous electrolyte storage element according to another aspect of the present invention has a positive electrode active material layer, the positive electrode active material layer containing a positive electrode active material, a solid electrolyte, and a binder, and substantially not containing a conductive agent, and the positive electrode active material layer has a discharge capacity density per area of ​​4 mAh / cm. 2 That's all.

[0019] The positive electrode for the nonaqueous electrolyte storage element described in [2] above has a discharge capacity density per area of ​​the positive electrode active material layer of 4 mAh / cm 2The cathode active material layer has a high discharge capacity density per area even when it contains typical voids. Furthermore, because the cathode active material layer is substantially free of a conductive agent, the content ratio of the solid electrolyte can be increased while maintaining a certain level of the cathode active material content in the cathode active material layer, thereby promoting the movement of charge-transporting ions in the cathode active material layer. The movement of electrons in the cathode active material layer can be ensured by the cathode active material. That is, the ionic conductivity of the cathode active material layer can be increased while maintaining a sufficiently high level of electronic conductivity. Furthermore, the cathode active material layer has a discharge capacity density per area within the above range, and even when it contains typical voids, the thickness of the cathode active material layer is considered to be relatively large. Therefore, ionic conduction in the cathode active material layer is likely to be the rate-limiting step in the charge-discharge reaction. By promoting the movement of charge-transporting ions, the charge-discharge reaction can proceed more uniformly. For these reasons, the positive electrode for a nonaqueous electrolyte storage element described in [2] above has a large discharge capacity density and can increase the initial coulomb efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0020] In the present invention, the "discharge capacity density per area of ​​the positive electrode active material layer" refers to the discharge capacity density per area of ​​each of one or more positive electrode active material layers. That is, for example, when one positive electrode active material layer is provided on each side of a positive electrode substrate, the discharge capacity density per area of ​​one positive electrode active material layer on each side is referred to. The discharge capacity density is a value calculated by the following formula (a). In the formula (a), the "discharge capacity density" refers to the discharge capacity density per unit area of ​​the positive electrode active material layer. In addition, in the formula (a), the "rated capacity" refers to the discharge capacity when a nonaqueous electrolyte storage element is fully charged and then discharged to a fully discharged state under charge / discharge conditions recommended or specified for the nonaqueous electrolyte storage element. In the case where a charger for the nonaqueous electrolyte storage element is provided, the "rated capacity" refers to the discharge capacity when the nonaqueous electrolyte storage element is charged using the charger and then discharged to a fully discharged state. The "effective area" refers to the area where the positive electrode active material layer and the negative electrode active material layer face each other. The nonaqueous electrolyte storage element is disassembled, and the opposing areas are measured from the removed electrode bodies. The opposing areas are preferably measured using, for example, a scanning microscope or an X-ray CT device. Furthermore, when the positive electrode active material layer and the negative electrode active material layer can be separated, it is more preferable to measure the opposing areas from the separated layers. Rated capacity of non-aqueous electrolyte storage element (mAh) / effective area of ​​positive electrode active material layer (cm 2 ) / number of positive electrode active material layers=discharge capacity density (mAh / cm 2 ) (a)

[0021] [3] In the positive electrode for a nonaqueous electrolyte storage element according to [1] or [2] above, the content of the positive electrode active material in the positive electrode active material layer may be 30% by volume or more.

[0022] The positive electrode for a nonaqueous electrolyte storage element described in [3] above has a positive electrode active material content within the above range, thereby ensuring sufficient electronic conductivity of the positive electrode active material layer, and thus easily increasing the discharge capacity density while also easily increasing the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0023] [4] In the positive electrode for the nonaqueous electrolyte storage element according to any one of [1] to [3] above, the content of the solid electrolyte in the positive electrode active material layer may be 10% by volume or more.

[0024] The positive electrode for a nonaqueous electrolyte storage element described in [4] above has a solid electrolyte content within the above range, and therefore can easily increase the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0025] The volumetric content of the positive electrode active material and solid electrolyte in the positive electrode active material layer is measured by observing a cross section of the positive electrode prepared by the above-described procedure with a scanning electron microscope or the like.

[0026] In the present invention, the volumetric content in the positive electrode active material layer means the content relative to the volume of the entire positive electrode active material layer, including voids, and the same applies to the following description of the present invention unless otherwise explicitly stated. The voids in the positive electrode active material layer are usually about 10% by volume.

[0027] [5] In the positive electrode for a nonaqueous electrolyte storage element according to any one of [1] to [4] above, the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer may be 80% by volume or more.

[0028] The positive electrode for a nonaqueous electrolyte storage element described in [5] above has a total content of the positive electrode active material and the solid electrolyte within the above range, and therefore has few components other than the positive electrode active material and the solid electrolyte, voids, etc. This results in a larger discharge capacity density and can further increase the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0029] [6] In the positive electrode for the nonaqueous electrolyte storage element according to any one of [1] to [5] above, the positive electrode active material may be a lithium transition metal composite oxide.

[0030] In general, solid electrolytes are prone to side reactions with lithium transition metal composite oxides. Therefore, in nonaqueous electrolyte energy storage elements having a positive electrode containing a solid electrolyte and a lithium transition metal composite oxide, the initial coulombic efficiency and the discharge capacity at high rate discharge tend to decrease. Therefore, the positive electrode for a nonaqueous electrolyte energy storage element described in [6] above significantly achieves the advantages of the present invention, namely, increasing the initial coulombic efficiency and the discharge capacity at high rate discharge of the nonaqueous electrolyte energy storage element.

[0031] [7] In the positive electrode for a nonaqueous electrolyte storage element according to any one of [1] to [6] above, the solid electrolyte may be a sulfide solid electrolyte.

[0032] In general, sulfide solid electrolytes tend to undergo side reactions with positive electrode active materials. Therefore, in nonaqueous electrolyte storage elements having a positive electrode containing a sulfide solid electrolyte and a positive electrode active material, the initial coulombic efficiency and the discharge capacity at high rate discharge tend to decrease. Therefore, the positive electrode for a nonaqueous electrolyte storage element described in [7] above significantly achieves the advantages of the present invention, namely, increasing the initial coulombic efficiency and the discharge capacity at high rate discharge of the nonaqueous electrolyte storage element.

[0033] [8] A nonaqueous electrolyte storage element according to another aspect of the present invention includes the positive electrode for the nonaqueous electrolyte storage element according to any one of [1] to [7] above.

[0034] The nonaqueous electrolyte storage element described in [8] above includes the positive electrode for a nonaqueous electrolyte storage element described in any one of [1] to [7] above, and therefore has a large discharge capacity density, a high initial coulombic efficiency, and a high discharge capacity during high-rate discharge.

[0035] [9] The nonaqueous electrolyte electricity storage element according to [8] above may be an all-solid-state electricity storage element.

[0036] The nonaqueous electrolyte electricity storage element described in [9] above is an all-solid-state electricity storage element, and therefore the advantages of the present invention, such as a large discharge capacity density, a high initial coulomb efficiency, and a high discharge capacity during high-rate discharge, can be particularly remarkably obtained.

[0037] A positive electrode for a nonaqueous electrolyte storage element, a nonaqueous electrolyte storage element, a method for manufacturing a nonaqueous electrolyte storage element, an electricity storage device, and other embodiments according to one embodiment of the present invention will be described in detail below. Note that the lower and upper limits of each numerical range described in the embodiments of the present invention can be combined in any desired manner.

[0038] [Positive electrode] First Embodiment The positive electrode for a nonaqueous electrolyte storage element according to a first embodiment of the present invention (hereinafter also simply referred to as "positive electrode") has a positive electrode substrate and a positive electrode active material layer laminated on the positive electrode substrate directly or via an intermediate layer. Typically, the positive electrode has a portion where the positive electrode substrate is exposed. This exposed portion of the positive electrode substrate is typically connected to the above-mentioned positive electrode lead. The positive electrode may have a shape such as a sheet, plate, or strip. When the positive electrode has a positive electrode active material layer with the configuration described below, the positive electrode has a large discharge capacity density and can increase the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0039] The positive electrode substrate has electrical conductivity. In this specification, "having electrical conductivity" means that the volume resistivity is 10 -2 The volume resistivity is a value measured in accordance with JIS-H-0505 (1975). On the other hand, in this specification, "not having electrical conductivity" or "having (electrical) insulation" means that the volume resistivity is 10 7 This means that the resistance is Ω·cm or more.

[0040] Examples of materials for the positive electrode substrate include metals such as aluminum, titanium, iron, and alloys thereof (stainless steel, etc.). Among these, aluminum or an aluminum alloy is preferred from the viewpoints of potential resistance, high electronic conductivity, and cost.

[0041] The positive electrode substrate has a shape such as a sheet, plate, or strip. Examples of the form of the positive electrode substrate include foil, vapor-deposited film, mesh, and porous material, and foil is preferred. The positive electrode substrate may be, for example, aluminum foil or aluminum alloy foil.

[0042] The average thickness of the positive electrode substrate may be, for example, 3 μm or more and 50 μm or less. The lower limit of the average thickness of the positive electrode substrate may be 5 μm, 8 μm, 10 μm, or 15 μm. The upper limit of the average thickness of the positive electrode substrate may be 40 μm, 30 μm, 20 μm, or 15 μm.

[0043] The intermediate layer is a layer disposed between the positive electrode substrate and the positive electrode active material layer. The intermediate layer contains, for example, a conductive agent and a binder. When the intermediate layer contains a conductive agent, the contact resistance between the positive electrode substrate and the positive electrode active material layer can be reduced. Examples of the conductive agent and binder used in the intermediate layer include the same conductive agent and binder used in the positive electrode active material layer described below.

[0044] The positive electrode active material layer includes a positive electrode active material, a solid electrolyte, and a binder. The positive electrode active material layer is substantially free of a conductive agent. The positive electrode active material layer includes optional components such as a thickener and a filler, as necessary. The positive electrode active material layer may be formed from a positive electrode mixture including a positive electrode active material, a solid electrolyte, a binder, and other optional components. As in the all-solid-state energy storage element 1 of FIG. 1, the positive electrode active material layer may be provided on only one side of a positive electrode substrate having a shape such as a sheet. In another embodiment, the positive electrode active material layer may be provided on both sides of the positive electrode substrate.

[0045] (Cathode active material) Known positive electrode active materials can be used for the positive electrode active material. Positive electrode active materials for lithium ion secondary batteries typically use materials capable of absorbing and releasing lithium ions. Examples of positive electrode active materials include lithium transition metal composite oxides, polyanion compounds, chalcogen compounds, sulfur-based materials, and lithium oxide. To significantly achieve the advantages of the present invention, namely, increasing the initial coulombic efficiency and high-rate discharge capacity of the nonaqueous electrolyte storage element, the positive electrode active material is preferably a lithium transition metal composite oxide. The positive electrode active material may contain one or more materials.

[0046] Examples of transition metal elements contained in the lithium transition metal composite oxide include nickel, cobalt, and manganese. The lithium transition metal composite oxide may also contain a typical metal element such as aluminum. Examples of the lithium transition metal composite oxide include lithium transition metal composite oxides having an α-NaFeO2 crystal structure and lithium transition metal composite oxides having a spinel crystal structure. The surface of the lithium transition metal composite oxide may be coated with another material. Examples of the other material include compounds containing niobium and oxygen, such as lithium niobate.

[0047] Lithium transition metal composite oxides with an α-NaFeO2 type crystal structure include Li 1+α Ma 1-α 02 (Ma is a metal element other than lithium that contains one or more transition metal elements, with 0≦α<1). Ma preferably contains one or more of Ni, Co, and Mn. The total content of Ni, Co, and Mn relative to Ma ((Ni+Co+Mn) / Ma) is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 98 mol % or more. Ma also preferably contains one or more of Ni, Co, and Mn and Al, or preferably contains Ni, Co, Mn, and Al. The total content of Ni, Co, Mn, and Al relative to Ma ((Ni+Co+Mn+Al) / Ma) is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 98 mol % or more.

[0048] In a lithium transition metal composite oxide having an α-NaFeO2-type crystal structure, the lower limit of the molar ratio of Ni to a metal element other than lithium (Ma) is preferably 0.4, more preferably 0.5, even more preferably 0.6, and even more preferably 0.7 or 0.8. When the molar ratio of Ni is equal to or greater than the lower limit, the energy density of the energy storage device can be easily increased, but lithium ions in the lithium transition metal composite oxide are likely to be released, and side reactions between the lithium transition metal composite oxide and the solid electrolyte are likely to occur. Therefore, the advantages of the present invention are particularly pronounced. On the other hand, the upper limit of the molar ratio of Ni is preferably 0.95, more preferably 0.9, even more preferably 0.85, and even more preferably 0.82.

[0049] In the lithium transition metal composite oxide having an α-NaFeO2-type crystal structure, the lower limit of the molar ratio of Co to the metal element other than lithium (Ma) is preferably 0.05, more preferably 0.075, and in some cases even more preferably 0.10 or 0.15. Meanwhile, the upper limit of the molar ratio of Co is preferably 0.30, more preferably 0.20. When the molar ratio of Co is within the above range, it is possible to easily suppress a decrease in the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0050] In the lithium transition metal composite oxide having an α-NaFeO2-type crystal structure, the lower limit of the molar ratio of Al to the metal element other than lithium (Ma) is preferably 0.005, more preferably 0.01, and in some cases even more preferably 0.02 or 0.05. On the other hand, the upper limit of the molar ratio of Al is preferably 0.10, more preferably 0.08. When the molar ratio of Al is within the above range, it is possible to easily suppress a decrease in the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0051] Lithium transition metal composite oxides with spinel-type crystal structures include Li βThose represented by Mb2O4 (where Mb is a metal element other than lithium element, including one or more transition metal elements, and 0 < β ≦ 1.2) can be mentioned. Mb preferably contains Mn. The content of Mn with respect to Mb (Mn / Mb) is preferably 50 mol% or more, and more preferably 80 mol% or more.

[0052] A polyanion compound is a compound composed of a polyanion (that is, a polyvalent anion) and a cation. The polyanion compound preferably contains a lithium cation and a transition metal cation as the cation. Examples of the polyanion compound include LiFePO4, LiMnPO4, LiMn x Fe 1-x PO4 (0 < x < 1), LiNiPO4, LiCoPO4, Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, etc. The surface of the polyanion compound may be coated with, for example, a carbon material described later.

[0053] Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc.

[0054] Examples of the sulfur-based material include elemental sulfur, metal sulfides such as lithium sulfide, organic disulfide compounds, and organic sulfur compounds such as carbon sulfide compounds.

[0055] Atoms or polyanions in these materials that are the positive electrode active material may be partially substituted with atoms or anion species composed of other elements. The surfaces of these materials may be coated with other materials.

[0056] The positive electrode active material is usually particulate. The average particle size of the positive electrode active material is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 10 μm, and even more preferably 1 μm to 5 μm. Setting the average particle size of the positive electrode active material above the lower limit facilitates the production and handling of the positive electrode active material. Setting the average particle size of the positive electrode active material below the upper limit improves the electronic conductivity of the positive electrode active material layer. When a composite of the positive electrode active material and another material is used, the average particle size of the composite is taken as the average particle size of the positive electrode active material. The term "average particle size" refers to the value at which the volume-based cumulative distribution (D50) reaches 50% as calculated in accordance with JIS-Z-8819-2 (2001) based on the particle size distribution measured by laser diffraction / scattering in a diluted solution of particles diluted with a solvent in accordance with JIS-Z-8825 (2013). As a method for obtaining particles of the positive electrode active material and the negative electrode active material described below with a predetermined particle size, a known method using, for example, a pulverizer, a classifier, or the like can be employed.

[0057] The lower limit of the content of the lithium transition metal composite oxide in the total positive electrode active material in the positive electrode active material layer is preferably 50 mass%, more preferably 70 mass%, and even more preferably 90 mass%, and the content of the lithium transition metal composite oxide in the total positive electrode active material in the positive electrode active material layer may be 100 mass%.

[0058] The lower limit of the content of the positive electrode active material in the positive electrode active material layer is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and even more preferably 80% by mass. On the other hand, the upper limit of the content of the positive electrode active material in the positive electrode active material layer is preferably 90% by mass, more preferably 85% by mass. By setting the content of the positive electrode active material to the above lower limit or more, the discharge capacity density of the positive electrode can be easily increased. Furthermore, by setting the content of the positive electrode active material to the above upper limit or less, the content of the solid electrolyte in the positive electrode active material layer can be ensured, and therefore, a decrease in the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element can be easily suppressed.

[0059] The lower limit of the content of the positive electrode active material in the positive electrode active material layer is preferably 30% by volume, more preferably 40% by volume, even more preferably 50% by volume, and even more preferably 60% by volume. On the other hand, the upper limit of the content of the positive electrode active material may be 80% by volume, preferably 70% by volume, and in some cases, preferably 65% ​​by volume. By setting the content of the positive electrode active material at or above the lower limit, it is possible to easily increase the discharge capacity density while easily increasing the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element. Furthermore, by setting the content of the positive electrode active material at or below the upper limit, it is possible to easily ensure the content of the solid electrolyte in the positive electrode active material layer.

[0060] The lower limit of the content of the positive electrode active material, based on the total volume of the positive electrode active material layer excluding the voids, is preferably 30% by volume, more preferably 40% by volume, even more preferably 50% by volume, and even more preferably 60% by volume. Meanwhile, the upper limit of the content of the positive electrode active material may be 80% by volume, preferably 70% by volume. By setting the content of the positive electrode active material at or above the lower limit, it is possible to easily increase the discharge capacity density while easily increasing the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element. Furthermore, by setting the content of the positive electrode active material at or below the upper limit, it is possible to easily ensure the content of the solid electrolyte in the positive electrode active material layer.

[0061] (solid electrolyte) The term "solid electrolyte" refers to an electrolyte that maintains a solid state at 25°C under a nitrogen atmosphere. Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, dry polymer electrolytes, gel polymer electrolytes, and pseudo-solid electrolytes. A sulfide solid electrolyte is preferred as the solid electrolyte. When the solid electrolyte contained in the positive electrode active material layer is a sulfide solid electrolyte, side reactions are likely to occur between the sulfide solid electrolyte and the positive electrode active material, such as a lithium transition metal composite oxide. This significantly enhances the advantages of the present invention, such as increasing the initial coulombic efficiency and high-rate discharge capacity of the nonaqueous electrolyte storage element. The solid electrolyte may be a solid electrolyte other than a sulfide solid electrolyte. The upper limit of the oxygen element content in the solid electrolyte may be 10 mol%, 1 mol%, or 0.1 mol%. The solid electrolyte may be a crystalline solid electrolyte or an amorphous solid electrolyte. A crystalline solid electrolyte refers to a solid electrolyte in which a peak attributable to the solid electrolyte is observed in the X-ray diffraction pattern. The amorphous solid electrolyte refers to a solid electrolyte whose X-ray diffraction pattern is a halo pattern in which no peaks other than those derived from the raw materials are substantially observed. One or more types of solid electrolytes can be used.

[0062] The sulfide solid electrolyte preferably contains at least sulfur element and further contains lithium element. The sulfide solid electrolyte preferably has lithium ion conductivity. The sulfide solid electrolyte preferably also contains phosphorus element and preferably further contains a halogen element. The sulfide solid electrolyte preferably contains at least one of bromine element and iodine element as the halogen element.

[0063] When the sulfide solid electrolyte is a crystalline solid electrolyte, its crystal structure may be an argyrodite crystal structure, a Li3PS4 crystal structure, a Li4P2S6 crystal structure, or a Li7P3S 11 Crystal structure, Li 10 GeP2S 12Examples of sulfide solid electrolytes include a sulfide solid electrolyte having a crystalline structure, such as a crystalline structure, a Thio-LISICON type crystalline structure, an inverse fluorite type crystalline structure, a crystalline structure having diffraction peaks in the ranges of 19.9° ± 0.5° and 29.3° ± 0.5° in a diffraction angle 2θ in an X-ray diffraction pattern using CuKα rays, a crystalline structure having diffraction peaks in the ranges of 21.0 ± 0.5° and 28.0 ± 0.5° in a diffraction angle 2θ in an X-ray diffraction pattern using CuKα rays, and a crystalline structure having different diffraction peaks in the ranges of 17.9° ± 0.5° or 19.1° ± 0.5° in a diffraction angle 2θ of 29.1° ± 0.5° in a diffraction angle 2θ of 29.8° ± 0.5° in an X-ray diffraction pattern using CuKα rays, and any of these diffraction peaks is the maximum diffraction peak.

[0064] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-Li3N, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S 2n (where m and n are positive numbers, and Z is Ge, Zn, or Ga.), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In.) Li 10 GeP2S 12 etc.

[0065] In the positive electrode active material layer, the solid electrolyte may form a complex with the positive electrode active material. Such a complex may further contain components other than the solid electrolyte and the positive electrode active material.

[0066] The content of the solid electrolyte in the positive electrode active material layer is preferably 5% by mass or more and 50% by mass or less, and may be 10% by mass or more and 40% by mass or less, or may be 12% by mass or more and 30% by mass or less.

[0067] The lower limit of the solid electrolyte content in the positive electrode active material layer is preferably 10 vol%, more preferably 15 vol%, even more preferably 18 vol%, and even more preferably 22 vol% in some cases. On the other hand, the upper limit of the solid electrolyte content is preferably 50 vol%, more preferably 40 vol%, even more preferably 30 vol%, and even more preferably 25 vol% in some cases. By setting the solid electrolyte content at or above the lower limit, it is possible to easily suppress a decrease in the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element. Furthermore, by setting the solid electrolyte content at or below the upper limit, it is possible to easily ensure the content of the positive electrode active material in the positive electrode active material layer.

[0068] The lower limit of the solid electrolyte content, based on the total volume of the positive electrode active material layer excluding voids, is preferably 10% by volume, more preferably 15% by volume, even more preferably 20% by volume, and even more preferably 24% by volume in some cases. Meanwhile, the upper limit of the solid electrolyte content is preferably 50% by volume, more preferably 40% by volume, even more preferably 30% by volume, and even more preferably 28% by volume in some cases. By ensuring that the solid electrolyte content is at or above the lower limit, it is possible to easily suppress a decrease in the initial coulombic efficiency and discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element. Furthermore, by ensuring that the solid electrolyte content is at or below the upper limit, it is possible to easily ensure the content of the positive electrode active material in the positive electrode active material layer.

[0069] The lower limit of the total content of the positive electrode active material and solid electrolyte in the positive electrode active material layer may be 75 mass%, preferably 80 mass%, and more preferably 90 mass%. By setting the total content at or above the lower limit, the discharge capacity density can be increased, and the initial coulombic efficiency and high-rate discharge capacity of the nonaqueous electrolyte storage element can be further increased. On the other hand, the upper limit of the total content may be 99 mass%, 98 mass%, or 97 mass%.

[0070] The lower limit of the total content of the positive electrode active material and solid electrolyte in the positive electrode active material layer may be 75 vol%, preferably 80 vol%, more preferably 82 vol%, and even more preferably 85 vol%. By setting the total content at or above the lower limit, the discharge capacity density of the positive electrode can be increased, and the initial coulombic efficiency and high-rate discharge capacity of the nonaqueous electrolyte storage element can be increased. On the other hand, the upper limit of the total content may be 99 vol%, 98 vol%, or 95 vol%.

[0071] The lower limit of the content of the positive electrode active material and solid electrolyte based on the total volume of the positive electrode active material layer excluding voids may be 75 vol%, but is preferably 80 vol%, more preferably 85 vol%, even more preferably 90 vol%, and even more preferably 95 vol%. By setting the total content at or above the lower limit, the discharge capacity density of the positive electrode can be increased, and the initial coulombic efficiency and high-rate discharge capacity of the nonaqueous electrolyte storage element can be increased. On the other hand, the upper limit of the total content may be 99 vol%, 98 vol%, or 97 vol%.

[0072] (Other ingredients) As described above, the positive electrode active material layer is substantially free of a conductive agent. Since the positive electrode active material layer is substantially free of a conductive agent, it becomes easy to increase the content ratio of the solid electrolyte while maintaining the content ratio of the positive electrode active material in the positive electrode active material layer at a certain level or higher, and the conductive agent is less likely to inhibit the movement of charge-transporting ions. Here, the conductive agent refers to a component made of a material having electrical conductivity. Even when the volume resistivity of the conductive agent cannot be directly measured, it is possible to measure the volume resistivity by measuring the volume resistivity of the conductive agent. -2Conductive agents are materials known to have a resistivity of Ω·cm or less. The aforementioned positive electrode active material and other materials, such as carbon materials coating the surface of the positive electrode active material, are not considered conductive agents. Examples of conductive agents include carbon materials, metals, and conductive ceramics. A carbon material refers to a material whose primary constituent element is carbon. The primary constituent element refers to the element with the highest content by mass. For example, the carbon content of a carbon material may be 80% by mass or more, 90% by mass or more, 95% by mass, 99% by mass, or 99.9% by mass or more. The carbon material is preferably a carbon material other than an uncarbonized polymer compound. Examples of carbon materials include graphite, non-graphitic carbon, and graphene-based carbon. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, and carbon black. Examples of carbon black include furnace black, acetylene black, and ketjen black. Examples of graphene-based carbon include graphene, carbon nanotubes (CNT), fullerene, etc. The conductive agent may be in the form of powder, fiber, or the like.

[0073] Examples of the binder include a water-based binder and an organic solvent-based binder.

[0074] The aqueous binder is a binder that dissolves or disperses in water. The aqueous binder may be a binder that dissolves or disperses at 1 part by mass or more in 100 parts by mass of water at 20°C. When a positive electrode active material layer is formed using a positive electrode mixture paste whose dispersion medium is water or a mixed solvent mainly composed of water, an aqueous binder (a water-soluble or water-dispersible polymer material) can be used. Examples of aqueous binders include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polytetrafluoroethylene, styrene-butadiene rubber, polyethylene, polypropylene, nitrile-butadiene rubber, and cellulose.

[0075] The organic solvent-based binder is a binder that dissolves or disperses in an organic solvent (e.g., N-methylpyrrolidone). The organic solvent-based binder may be a binder that dissolves or disperses at 1 part by mass or more in 100 parts by mass of an organic solvent (e.g., N-methylpyrrolidone) at 20°C. When a positive electrode active material layer is formed using a positive electrode mixture paste whose dispersion medium is an organic solvent or a mixed solvent mainly containing an organic solvent, an organic solvent-based binder (a polymer material that is soluble or dispersible in an organic solvent) can be used. Examples of organic solvent-based binders include polyvinylidene fluoride, copolymers of vinylidene fluoride and hexafluoropropylene, copolymers of ethylene and vinyl alcohol, polyacrylonitrile, polyphosphazene, polysiloxane, polyvinyl acetate, polymethyl methacrylate, polystyrene, polycarbonate, polyamide, polyimide, polyamideimide, crosslinked polymers of cellulose and chitosan pyrrolidone carboxylate, chitosan derivatives, and the like.

[0076] The binder may be a fluororesin (polytetrafluoroethylene, polyvinylidene fluoride, etc.), a polyolefin (polyethylene, polypropylene, etc.), an elastomer (ethylene propylene diene rubber, styrene butadiene rubber, fluororubber, etc.), a polysaccharide polymer (cellulose, chitosan derivatives, etc.), etc. One or more types of binders may be used.

[0077] The content of the binder in the positive electrode active material layer is preferably 0.1% by mass to 5% by mass, more preferably 0.3% by mass to 3% by mass, and more preferably 0.5% by mass to 2% by mass. The upper limit of the binder content may be 1.5%, 1.2%, or 1.0% by mass. By setting the binder content within the above range, the positive electrode active material can be stably maintained while the effects of the present invention can be easily obtained.

[0078] The content of the binder in the positive electrode active material layer is preferably 0.5% by volume to 6% by volume, more preferably 0.8% by volume to 4% by volume, and more preferably 1.0% by volume to 3% by volume. By setting the binder content within the above range, the positive electrode active material can be stably maintained while the effects of the present invention can be easily obtained.

[0079] The binder content, based on the total volume of the positive electrode active material layer excluding the voids, is preferably 0.5% by volume to 6% by volume, more preferably 0.8% by volume to 4% by volume, and more preferably 1.0% by volume to 3% by volume. By setting the binder content within the above range, the positive electrode active material can be stably maintained while the effects of the present invention can be easily obtained.

[0080] Examples of thickeners include polysaccharide polymers such as carboxymethyl cellulose, methyl cellulose, and ethyl cellulose. When the thickener has a functional group that reacts with lithium or the like, the functional group may be deactivated in advance by methylation or the like. The thickener may also function as a binder. One or more types of thickeners may be used. When the positive electrode active material layer contains a thickener, the content of the thickener in the positive electrode active material layer is preferably 0.1% by mass or more and 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. The technology disclosed herein may also be implemented in an embodiment in which the positive electrode active material layer does not contain a thickener.

[0081] The filler is not particularly limited. The filler may be a component other than the positive electrode active material, solid electrolyte, conductive agent, binder, and thickener, and may be intentionally added. The filler may be added to fill gaps in the positive electrode active material layer, or may be added for other purposes. The filler may be an organic substance such as polyolefin, or an inorganic substance such as an inorganic oxide, hydroxide, or carbonate. One or more fillers may be used. When the positive electrode active material layer contains a filler, the content of the filler in the positive electrode active material layer may be 0.1% by mass or more and 8% by mass or less, typically preferably 5% by mass or less, and more preferably 2% by mass or less. The technology disclosed herein may also be implemented in an embodiment in which the positive electrode active material layer does not contain a filler.

[0082] The positive electrode active material layer may further contain other components in addition to the positive electrode active material, solid electrolyte, binder, thickener, and filler. The other components include those unintentionally generated in the positive electrode active material layer. The positive electrode active material layer may also contain unintentionally contained impurities as the other components, as long as the effects of the present invention are achieved. The upper limit of the content of the other components in the positive electrode active material layer may be 5% by mass, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of the unintentionally generated components in the positive electrode active material layer may be 5% by mass, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of the unintentionally contained impurities in the positive electrode active material layer may be 5% by mass, 2%, 1%, 0.1%, or 0.01% by mass.

[0083] (physical properties, etc.) The upper limit of the voids in the positive electrode active material layer is preferably 20 vol%, more preferably 15 vol%, and even more preferably 12 vol%. By keeping the voids in the positive electrode active material layer at or below the upper limit, the effects of the present invention can be easily achieved. On the other hand, the lower limit of the voids in the positive electrode active material layer is not particularly limited, but may be 0.5 vol%, 1 vol%, or 5 vol%.

[0084] In the positive electrode according to the first embodiment of the present invention, the lower limit of the thickness of the positive electrode active material layer is 80 μm, preferably 90 μm, and more preferably 100 μm. By ensuring that the thickness of the positive electrode active material layer is equal to or greater than the above lower limit, the discharge capacity density per area of ​​the positive electrode and the nonaqueous electrolyte storage element can be increased. On the other hand, from the viewpoint of ensuring that the thickness of the positive electrode active material layer falls within an appropriate range that easily achieves the effects of the present invention, the upper limit of the thickness of the positive electrode active material layer is preferably 200 μm, more preferably 150 μm, and even more preferably 120 μm.

[0085] The mass per unit area of ​​one positive electrode active material layer is, for example, 4 mg / cm 2 More than 100mg / cm 2 The lower limit of the mass per unit area of ​​one positive electrode active material layer may be 6 mg / cm or less. 2 , 8 mg / cm 2 or 10 mg / cm 2 The upper limit of the mass per unit area of ​​one positive electrode active material layer is 50 mg / cm. 2 , 30 mg / cm 2 , or 25 mg / cm 2 may be.

[0086] Second Embodiment A positive electrode for a nonaqueous electrolyte storage element according to a second embodiment of the present invention includes a positive electrode substrate and a positive electrode active material layer laminated on the positive electrode substrate directly or via an intermediate layer. When the positive electrode active material layer has a configuration described below, the positive electrode has a high discharge capacity density and can increase the initial coulombic efficiency and the discharge capacity during high-rate discharge of the nonaqueous electrolyte storage element.

[0087] In the positive electrode according to the second embodiment of the present invention, the configurations of the positive electrode substrate and intermediate layer can be the same as those of the positive electrode according to the first embodiment of the present invention. In the positive electrode according to the second embodiment of the present invention, the positive electrode active material layer includes a positive electrode active material, a solid electrolyte, and a binder. The positive electrode active material layer is substantially free of a conductive agent. The positive electrode active material layer includes optional components such as a thickener and a filler as necessary. The positive electrode active material layer may be formed from a positive electrode mixture including a positive electrode active material, a solid electrolyte, a binder, and other optional components.

[0088] In the positive electrode according to the second embodiment of the present invention, the lower limit of the discharge capacity density per area of ​​the positive electrode active material layer is 4 mAh / cm 2 and 5mAh / cm 2 is preferred, and 6mAh / cm 2 On the other hand, from the viewpoint of setting the discharge capacity density in an appropriate range in which the effects of the present invention can be easily obtained, the upper limit of the discharge capacity density is 15 mAh / cm 2 is preferred, and 10 mAh / cm 2 is more preferable, and 8mAh / cm 2 is more preferable.

[0089] In the positive electrode according to the second embodiment of the present invention, the configuration of the positive electrode active material layer (components, content of each component, physical properties, etc.) other than the discharge capacity density per area of ​​the positive electrode active material layer can be the same as that of the positive electrode according to the first embodiment of the present invention.

[0090] [Non-aqueous electrolyte energy storage element] A nonaqueous electrolyte energy storage element according to one embodiment of the present invention comprises the positive electrode according to the first embodiment of the present invention or the positive electrode according to the second embodiment of the present invention, a negative electrode, a separator, and a container accommodating these. The separator is a layer interposed between the positive electrode and the negative electrode to electrically insulate the positive electrode from the negative electrode, and contains a solid electrolyte, which is a nonaqueous electrolyte. The solid electrolyte may also be contained in the positive electrode and the negative electrode. The nonaqueous electrolyte energy storage element according to one embodiment of the present invention is preferably an all-solid-state energy storage element.

[0091] An all-solid-state energy storage element 1 shown in FIG. 1 , which is one embodiment of the present invention, is a secondary battery in which a positive electrode 2 and a negative electrode 3 are arranged with a separator 4 interposed therebetween. The positive electrode 2 has a positive electrode substrate 5 and a positive electrode active material layer 6, with the positive electrode substrate 5 being the outermost layer of the positive electrode 2. The negative electrode 3 has a negative electrode substrate 7 and a negative electrode active material layer 8, with the negative electrode substrate 7 being the outermost layer of the negative electrode 2. In the all-solid-state energy storage element 1 shown in FIG. 1 , the negative electrode active material layer 8, the separator 4, the positive electrode active material layer 6, and the positive electrode substrate 5 are stacked in this order on the negative electrode substrate 7. An intermediate layer may be provided between the positive electrode substrate 5 and the positive electrode active material layer 6. Similarly, an intermediate layer may be provided between the negative electrode substrate 7 and the negative electrode active material layer 8. The all-solid-state energy storage element 1 may further include other components such as a container. Other components such as a container are omitted from the all-solid-state energy storage element 1 shown in FIG. 1 .

[0092] The nonaqueous electrolyte storage element according to one embodiment of the present invention may further include, for example, a positive electrode lead, a positive electrode external terminal, a negative electrode lead, and a negative electrode external terminal. The positive electrode lead and the negative electrode lead are housed in a container. The positive electrode external terminal and the negative electrode external terminal are provided outside the container. The positive electrode is electrically connected to the positive electrode external terminal via the positive electrode lead. The negative electrode is electrically connected to the negative electrode external terminal via the negative electrode lead.

[0093] Hereinafter, the main components constituting the nonaqueous electrolyte electricity storage element according to one embodiment of the present invention will be described in detail, focusing on the case where the nonaqueous electrolyte electricity storage element is an all-solid-state electricity storage element.

[0094] The positive electrode is the positive electrode according to the first embodiment of the present invention or the positive electrode according to the second embodiment of the present invention.

[0095] As described above, the negative electrode has a negative electrode substrate and a negative electrode active material layer laminated on the negative electrode substrate directly or via an intermediate layer. Usually, the negative electrode has a portion where the negative electrode substrate is exposed. This exposed portion of the negative electrode substrate is usually connected to the above-mentioned negative electrode lead. The negative electrode may have a shape such as a sheet, plate, or strip.

[0096] The thickness of the negative electrode is appropriately set depending on the application of the nonaqueous electrolyte storage element, etc. The average thickness of the negative electrode may be, for example, 30 μm or more and 1,000 μm or less. The lower limit of the average thickness of the negative electrode may be 50 μm, 100 μm, or 200 μm. The upper limit of the average thickness of the negative electrode may be 500 μm, 400 μm, 300 μm, 200 μm, or 100 μm. The average thickness of the negative electrode is the average thickness of a portion where the negative electrode active material layer is laminated on the negative electrode substrate directly or via an intermediate layer. When the negative electrode substrate has both a portion where the negative electrode active material layer is laminated on both sides and a portion where the negative electrode active material layer is laminated on only one side, the average thickness of the portion where the negative electrode active material layer is laminated on both sides of the negative electrode substrate is taken as the average thickness.

[0097] The negative electrode substrate is conductive. Examples of materials for the negative electrode substrate include metals such as copper, nickel, iron, and alloys thereof (such as stainless steel), and carbon materials. Among these, copper or copper alloys are preferred.

[0098] The negative electrode substrate has a shape such as a sheet, plate, or strip. Examples of the form of the negative electrode substrate include foil, vapor-deposited film, mesh, and porous material, and foil is preferred. The negative electrode substrate may be, for example, copper foil or copper alloy foil.

[0099] The average thickness of the negative electrode substrate may be, for example, 2 μm or more and 35 μm or less. The lower limit of the average thickness of the negative electrode substrate may be 3 μm, 4 μm, 5 μm, or 10 μm. The upper limit of the average thickness of the negative electrode substrate may be 30 μm, 20 μm, 15 μm, or 10 μm.

[0100] The structure of the intermediate layer of the negative electrode is not particularly limited, and can be selected from the structures exemplified for the intermediate layer of the positive electrode, for example.

[0101] The negative electrode active material layer contains a negative electrode active material. The negative electrode active material layer may contain optional components such as a solid electrolyte, a conductive agent, a binder, a thickener, and a filler, as necessary. The optional components such as the solid electrolyte, the conductive agent, the binder, the thickener, and the filler may be selected from the materials exemplified for the positive electrode above. The negative electrode active material layer may be formed from a negative electrode mixture containing a negative electrode active material and other optional components. As in the all-solid-state energy storage element 1 of FIG. 1, the negative electrode active material layer may be provided on only one side of a negative electrode substrate having a shape such as a sheet. In another embodiment, the negative electrode active material layer may be provided on both sides of the negative electrode substrate.

[0102] The negative electrode active material can be a known negative electrode active material. A material capable of absorbing and releasing lithium ions is typically used as the negative electrode active material for lithium ion secondary batteries. Examples of the negative electrode active material include metallic lithium; metals or semimetals such as silicon and tin; metal oxides or semimetal oxides such as silicon oxide, titanium oxide, and tin oxide; and Li4Ti5O. 12 , LiTiO 2、 Examples of the negative electrode active material include titanium-containing oxides such as TiNbO; polyphosphate compounds; silicon carbide; and carbon materials such as graphite and non-graphitic carbon. The surface of the graphite may be coated with other materials such as non-graphitic carbon. One or more negative electrode active materials may be used.

[0103] "Graphite" refers to a graphite material that has an average lattice spacing (d 002 ) is a carbon material with a particle size of 0.33 nm or more and less than 0.34 nm. Graphite includes natural graphite and artificial graphite.

[0104] "Non-graphitic carbon" refers to carbon that has an average lattice spacing (d 002 ) refers to a carbon material in which the particle size is 0.34 nm or more and 0.42 nm or less. Non-graphitizable carbon includes non-graphitizable carbon and graphitizable carbon. "Non-graphitizable carbon" refers to a carbon material in which the particle size is 0.34 nm or more and 0.42 nm or less. 002The term "easily graphitizable carbon" refers to a carbon material having a particle size of 0.36 nm or more and 0.42 nm or less. 002 This refers to carbon materials with a particle size of 0.34 nm or more and less than 0.36 nm.

[0105] Here, the "discharged state" of a carbon material refers to a state in which the carbon material, which is a negative electrode active material, is discharged so that lithium ions that can be absorbed and released during charging and discharging are sufficiently released from the carbon material. For example, this refers to a state in which the open circuit voltage of a half cell using a negative electrode containing a carbon material as a negative electrode active material as a working electrode and metallic lithium as a counter electrode is 0.7 V or higher.

[0106] The negative electrode active material may be in a particulate form. The average particle size of the negative electrode active material may be, for example, 1 nm or more and 100 μm or less. When the negative electrode active material is a carbon material, a titanium-containing oxide, a polyphosphate compound, or the like, the average particle size may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, Si oxide, Sn oxide, or the like, the average particle size may be 1 nm or more and 1 μm or less. By setting the average particle size of the negative electrode active material to be equal to or greater than the above lower limit, the production or handling of the negative electrode active material becomes easier. By setting the average particle size of the negative electrode active material to be equal to or less than the above upper limit, the electronic conductivity of the negative electrode active material layer is improved.

[0107] The content of the negative electrode active material in the negative electrode active material layer is, for example, preferably 60% by mass to 99% by mass, more preferably 90% by mass to 98% by mass. By setting the content of the negative electrode active material within this range, both high energy density and manufacturability of the negative electrode active material layer can be achieved.

[0108] When the negative electrode active material is a metal such as metallic lithium, the negative electrode active material layer may be in the form of a foil. The metallic lithium may exist as pure metallic lithium consisting essentially of elemental lithium, or may exist as a lithium alloy containing other metal elements. When the negative electrode active material is a metal such as metallic lithium, the content of elemental lithium in the negative electrode active material layer may be 90% by mass or more, 99% by mass or more, or even 100% by mass.

[0109] When the negative electrode active material layer contains a conductive agent, the content of the conductive agent in the negative electrode active material layer is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. The content of the conductive agent in the negative electrode active material layer may be 5% by mass or less, or may be 2% by mass or less. The technology disclosed herein may also be implemented in an embodiment in which the negative electrode active material layer does not contain a conductive agent.

[0110] When the negative electrode active material layer contains a solid electrolyte, the content of the solid electrolyte is preferably 5% by mass or more and 90% by mass or less, may be 10% by mass or more and 70% by mass or less, or may be 20% by mass or more and 50% by mass or less.

[0111] When the negative electrode active material layer contains a binder, the content of the binder in the negative electrode active material layer is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 8% by mass. The content of the binder in the negative electrode active material layer may be 5% by mass or less, or may be 2% by mass or less. The technology disclosed herein may also be implemented in an embodiment in which the negative electrode active material layer does not contain a binder.

[0112] When the negative electrode active material layer contains a thickener, the content of the thickener in the negative electrode active material layer is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 8% by mass or less. The content of the thickener in the negative electrode active material layer may be 5% by mass or less, or may be 2% by mass or less. The technology disclosed herein may also be implemented in an embodiment in which the negative electrode active material layer does not contain a thickener.

[0113] The filler in the negative electrode active material layer may be a component other than the negative electrode active material, solid electrolyte, conductive agent, binder, and thickener, and may be an intentionally contained component. The filler may be contained as a component to fill gaps in the negative electrode active material layer, or may be contained for other purposes. When the negative electrode active material layer contains a filler, the content of the filler in the negative electrode active material layer can be 0.1% by mass or more and 8% by mass or less, and typically 5% by mass or less is preferred, and 2% by mass or less is more preferred. The technology disclosed herein may also be implemented in an embodiment in which the negative electrode active material layer does not contain a filler.

[0114] The negative electrode active material layer may further contain components other than the negative electrode active material, solid electrolyte, conductive agent, binder, thickener, and filler. These other components include those unintentionally present in the negative electrode active material layer. The negative electrode active material layer may also contain unintentionally present impurities as the other components, as long as the effects of the present invention are achieved. The upper limit of the content of the other components in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of the unintentionally present components in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of the unintentionally present impurities in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass.

[0115] The thickness of the negative electrode active material layer is appropriately set depending on the type of negative electrode active material, the application of the non-aqueous electrolyte storage element, and the like. The average thickness of one negative electrode active material layer may be, for example, 5 μm or more and 1,000 μm or less. The lower limit of the average thickness of one negative electrode active material layer may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, or 100 μm. The upper limit of the average thickness of one negative electrode active material layer may be 800 μm, 500 μm, 200 μm, 100 μm, 80 μm, 60 μm, or 40 μm. The mass per unit area of ​​one negative electrode active material layer is, for example, 2 mg / cm. 2More than 50mg / cm 2 The lower limit of the mass per unit area of ​​one negative electrode active material layer may be 3 mg / cm or less. 2 , 4 mg / cm 2 , 5 mg / cm 2 or 6 mg / cm 2 The upper limit of the mass per unit area of ​​one negative electrode active material layer is 30 mg / cm. 2 , 20 mg / cm 2 , 15 mg / cm 2 , 12 mg / cm 2 or 10 mg / cm 2 may be.

[0116] (isolation layer) The separator typically contains a solid electrolyte. The solid electrolyte can be selected from the materials exemplified for the positive electrode. The content of the solid electrolyte in the separator is preferably 70% by mass or more and 100% by mass or less. The content of the solid electrolyte in the separator may be 90% by mass or more, 99% by mass or more, or 100% by mass.

[0117] The separator layer may contain optional components such as additives (e.g., phosphate compounds such as LiPO, oxides, and halogen compounds), binders, thickeners, fillers, etc. The optional components such as binders, thickeners, and fillers can be selected from the materials exemplified for the positive electrode active material layer.

[0118] The average thickness of the separator layer is preferably 1 μm or more and 100 μm or less, more preferably 2 μm or more and 50 μm or less, and even more preferably 3 μm or more and 20 μm or less. By setting the average thickness of the separator layer to the above lower limit or more, it is possible to insulate the positive electrode and the negative electrode with high reliability. By setting the average thickness of the separator layer to the above upper limit or less, it is possible to increase the energy density of the nonaqueous electrolyte storage element.

[0119] (container) The container accommodates the positive electrode, the negative electrode, etc. in its internal space. Metallic materials such as aluminum and stainless steel, resinous materials, etc. are used as the container material, and metallic materials are preferred from the viewpoint of strength, etc. Composite materials of metallic materials and resinous materials, etc. may also be used.

[0120] The shape of the container is not particularly limited, and may be cylindrical, rectangular (square), disk-like, etc. The container may also be in the shape of a sheet formed from a metal resin composite film.

[0121] (shape, use, etc. of non-aqueous electrolyte storage element) The shape of the nonaqueous electrolyte storage element according to one embodiment of the present invention is not particularly limited, and may be, for example, a cylindrical battery, a prismatic battery, a flat battery, a coin battery, a button battery, or the like.

[0122] The use of the nonaqueous electrolyte electricity storage element according to one embodiment of the present invention is not particularly limited, and the nonaqueous electrolyte electricity storage element can be used, for example, as a power source for automobiles such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles, a power source for electronic devices such as personal computers and communication terminals, a power source for power storage, etc.

[0123] The nonaqueous electrolyte electricity storage element of the present invention may be used singly or in plural. When the required output and required voltage are small, the nonaqueous electrolyte electricity storage element may be used singly. On the other hand, when at least one of the required output and required voltage is large, the nonaqueous electrolyte electricity storage element may be used as an electricity storage device in combination with other nonaqueous electrolyte electricity storage elements. In an electricity storage device in which a plurality of nonaqueous electrolyte electricity storage elements are combined, at least one nonaqueous electrolyte electricity storage element included in the electricity storage device may be the nonaqueous electrolyte electricity storage element according to one embodiment of the present invention. The electricity storage device will be described in detail later.

[0124] In a nonaqueous electrolyte energy storage element according to one embodiment of the present invention, for example, the container may be constrained so as to maintain a constant thickness, or may not be constrained in this manner. Furthermore, the container may be constrained so as to apply a constant load. When the container is constrained, expansion of the container due to charge / discharge cycles, etc., may be suppressed, and deterioration of charge / discharge performance may be suppressed. When the container is constrained, a load may or may not be applied to the positive electrode and negative electrode within the container. For example, a constraining member that performs such constraining may be provided in the nonaqueous electrolyte energy storage element or the energy storage device.

[0125] [Method of manufacturing nonaqueous electrolyte energy storage element] The nonaqueous electrolyte energy storage element according to one embodiment of the present invention can be manufactured by a known method, for example, by preparing a positive electrode mixture, preparing a separator material, preparing a negative electrode mixture, and stacking the positive electrode, separator, and negative electrode.

[0126] Preparing a positive electrode mixture may mean producing a positive electrode mixture. The method for preparing the positive electrode mixture is not particularly limited and can be appropriately selected depending on the purpose. For example, the positive electrode mixture can be prepared by mixing a positive electrode active material and a solid electrolyte using a mechanical milling method or the like. It is also possible to produce a composite of the positive electrode active material and the solid electrolyte in advance, and then mix the obtained composite with other components.

[0127] Preparing an isolation layer material may mean fabricating an isolation layer material. A solid electrolyte as an isolation layer material can be fabricated by a conventionally known method. For example, it can be obtained by processing a predetermined material by mechanical milling. The isolation layer material may also be fabricated by heating predetermined materials to a melting temperature or higher by melt-quenching, melt-mixing the two at a predetermined ratio, and then quenching. Other methods for fabricating an isolation layer material include, for example, a solid-phase method in which the material is sintered under reduced pressure, a liquid-phase method such as solution deposition, a vapor-phase method (PLD), and sintering in an argon atmosphere after processing by mechanical milling.

[0128] Preparing the negative electrode mixture may be preparing a negative electrode mixture. The specific method for preparing the negative electrode mixture is the same as that for the positive electrode mixture. When a metal such as metallic lithium is used as the negative electrode active material, a metal foil that will become the negative electrode active material layer may be prepared instead of preparing the negative electrode mixture.

[0129] By stacking a positive electrode, a separator, and a negative electrode, for example, a positive electrode having a positive electrode substrate and a positive electrode active material layer, a separator, and a negative electrode having a negative electrode substrate and a negative electrode active material layer are stacked. In this process, the positive electrode, the separator, and the negative electrode may be formed sequentially in this order, or vice versa, and the order of forming each layer is not particularly important. For example, the positive electrode is formed by pressure molding a positive electrode substrate and a positive electrode mixture, the separator is formed by pressure molding an separator material, and the negative electrode is formed by pressure molding a negative electrode substrate and a negative electrode mixture. The positive electrode, the separator, and the negative electrode may be stacked by pressure molding the positive electrode substrate, the positive electrode mixture, the separator material, the negative electrode mixture, and the negative electrode substrate all at once. The positive electrode and the negative electrode may be formed in advance, and then pressure molded and stacked with the separator.

[0130] [Electricity storage device] 2 includes a plurality of power storage units 20. Each power storage unit 20 includes a plurality of electrically connected all-solid-state power storage elements 1. The power storage device 30 may include a bus bar (not shown) that electrically connects the plurality of all-solid-state power storage elements 1, a bus bar (not shown) that electrically connects the plurality of power storage units 20, etc. The power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more all-solid-state power storage elements 1.

[0131] [Other embodiments] The nonaqueous electrolyte storage element of the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention. For example, the configuration of one embodiment may be added to the configuration of another embodiment, or part of the configuration of one embodiment may be replaced with the configuration of another embodiment or well-known technology. Furthermore, part of the configuration of one embodiment may be deleted. Also, well-known technology may be added to the configuration of one embodiment.

[0132] In the above embodiment, the nonaqueous electrolyte storage element is used as a chargeable and dischargeable nonaqueous electrolyte secondary battery, but the nonaqueous electrolyte storage element may be of any type, shape, size, capacity, etc. The present invention can also be applied to various secondary batteries, electric double layer capacitors, lithium ion capacitors, and other capacitors.

[0133] For example, the nonaqueous electrolyte storage element according to the present invention may include layers other than the positive electrode, separator, and negative electrode. The present invention can also be applied to nonaqueous electrolyte storage elements including bipolar electrodes. Furthermore, the nonaqueous electrolyte storage element according to the present invention may contain a liquid. Examples of such nonaqueous electrolyte storage elements include nonaqueous electrolyte storage elements in which voids in the positive electrode active material layer 6, separator 4, negative electrode active material layer 8, etc. in the all-solid-state storage element 1 described above are filled with a nonaqueous electrolyte solution containing an ionic liquid or the like. [Example]

[0134] [Preparation of positive electrode mixture] <No.1> As the positive electrode active material, LiNi 0.8 Co 0.15 Al 0.05Particles (average particle size 3 μm) obtained by coating a lithium transition metal composite oxide represented by O2 with LiNbO3 were used. A mixture was prepared by weighing out the positive electrode active material, an argyrodite-type sulfide solid electrolyte represented by Li6PS5Cl, and a fluororesin binder in a mass ratio of 84.0:14.8:1.2. This mixture was then mixed with butyl butyrate as a solvent to a solids ratio of 70 mass% and kneaded in a hybrid mixer to produce No. 1 positive electrode mixture.

[0135] <No.2> A positive electrode mixture No. 2 was prepared in the same manner as in No. 1, except that the positive electrode active material, sulfide solid electrolyte, and binder were the same as in No. 1, and the positive electrode active material, sulfide solid electrolyte, fibrous carbon as a conductive agent, and binder were weighed in a mass ratio of 84.0:13.8:1.0:1.2.

[0136] <No.3> A positive electrode mixture No. 3 was prepared in the same manner as in No. 1, except that the positive electrode active material, sulfide solid electrolyte, and binder were the same as in No. 1, and the positive electrode active material, sulfide solid electrolyte, fibrous carbon as a conductive agent, and binder were weighed in a mass ratio of 84.0:12.8:2.0:1.2.

[0137] In the positive electrodes fabricated using the positive electrode mixtures No. 1 to No. 3 according to the procedure described below, the volumetric content of each component in the positive electrode active material layer was as shown in Table 1.

[0138] [Table 1]

[0139] [Example 1] The No. 1 positive electrode mixture was applied to the aluminum foil (average thickness 20 μm) that was the positive electrode substrate using a YBA type Baker applicator so that the mass per unit area was 30 mg / cm in solid content terms. 2 More than 40mg / cm 2The coating was performed as follows. The coating was dried in a dryer in an argon atmosphere set at 100°C under normal pressure for 10 minutes and then under reduced pressure for 10 minutes, thereby forming a positive electrode active material layer on the positive electrode substrate. This was punched out into a circle with a diameter of 10 mm to form the positive electrode of Example 1.

[0140] A nonaqueous electrolyte storage element (all-solid-state storage element) was fabricated using the positive electrode of Example 1. 80 mg of an argyrodite-type sulfide solid electrolyte represented by Li6PS5Cl was inserted into a ceramic powder compactor with an inner diameter of 10 mm as the separator material and pressure-molded using a uniaxial press at a pressure of 50 MPa for several seconds to form an separator. After releasing the pressure, the fabricated positive electrode was placed on one side of the separator and pressure-molded using a uniaxial press at 160°C and 400 MPa for 5 minutes. After releasing the pressure, indium foil and lithium foil as the negative electrode and copper foil as the negative electrode substrate were placed on the side opposite the bonding surface of the positive electrode and bonded using a uniaxial press at a pressure of 50 MPa for several seconds. The resultant was removed from the powder compactor to obtain the nonaqueous electrolyte storage element (all-solid-state storage element) of Example 1. The discharge capacity density of the positive electrode and the thickness of the positive electrode active material layer (active material layer thickness) are shown in Table 2. The thickness of the positive electrode active material layer was calculated by measuring the thickness of a molded body obtained by placing two of the above positive electrodes opposite each other and pressure-molding them using a uniaxial press at 160°C and 400 MPa for 5 minutes, using a micrometer, and multiplying the thickness of the positive electrode active material layer excluding the positive electrode substrate by 0.5.

[0141] [Comparative Example 1] A positive electrode and a nonaqueous electrolyte storage element (all-solid-state storage element) of Comparative Example 1 were obtained in the same manner as in Example 1, except that No. 2 positive electrode mixture was used and the thickness of the positive electrode active material layer was set as shown in Table 2.

[0142] Comparative Example 2 A positive electrode and a nonaqueous electrolyte storage element (all-solid-state storage element) of Comparative Example 2 were obtained in the same manner as in Example 1, except that No. 3 positive electrode mixture was used and the thickness of the positive electrode active material layer was set as shown in Table 2.

[0143] Comparative Example 3 The mass per unit area of ​​the No. 1 positive electrode mixture converted to solid content is 15 mg / cm 2 More than 25mg / cm 2 The positive electrode substrate was coated as follows, and a positive electrode and a nonaqueous electrolyte storage element (all-solid-state storage element) of Comparative Example 3 were obtained in the same manner as in Example 1, except that the thickness of the positive electrode active material layer was as shown in Table 2.

[0144] Comparative Example 4 The mass per unit area of ​​the No. 2 positive electrode mixture converted to solids is 15 mg / cm 2 More than 25mg / cm 2 The positive electrode substrate was coated as follows, and a positive electrode and a nonaqueous electrolyte storage element (all-solid-state storage element) of Comparative Example 4 were obtained in the same manner as in Example 1, except that the thickness of the positive electrode active material layer was as shown in Table 2.

[0145] Comparative Example 5 The mass per unit area of ​​the No. 3 positive electrode mixture converted to solids is 15 mg / cm 2 More than 25mg / cm 2 The positive electrode substrate was coated as follows, and a positive electrode and a nonaqueous electrolyte storage element (all-solid-state storage element) of Comparative Example 5 were obtained in the same manner as in Example 1, except that the thickness of the positive electrode active material layer was as shown in Table 2.

[0146] [evaluation] (Capacity confirmation test) For each of the all-solid-state electricity storage elements of the Examples and Comparative Examples, a capacity confirmation test was carried out at 25° C. in the following manner. Constant current / constant voltage charging was performed with a charging current of 0.1 C and a charge cut-off voltage of 3.75 V. The charge was terminated when the charging current reached 0.025 C. A 10-minute rest period was then provided. Subsequently, constant current discharging was performed with a discharging current of 0.1 C and a discharge cut-off voltage of 2.25 V. A 10-minute rest period was then provided. These charge and discharge steps constitute one cycle, and two cycles were repeated. The discharge capacity in the first cycle was divided by the charge capacity in the first cycle to determine the initial coulombic efficiency. The initial coulombic efficiency of each all-solid-state energy storage element is shown in Table 2.

[0147] (Various rate discharge tests) Following the above capacity confirmation test, each of the all-solid-state energy storage elements of the Examples and Comparative Examples was subjected to a discharge test at various rates at 25° C. in the following manner. Constant current / constant voltage charging was performed with a charging current of 0.1C and a charge cut-off voltage of 3.75V. The charge was terminated when the charging current reached 0.025C. A 10-minute rest period was then provided. Subsequently, constant current discharging was performed with a discharging current of 0.1C and a discharge cut-off voltage of 2.25V. A 10-minute rest period was then provided. The discharge capacity at this time was defined as the discharge capacity at a discharge current of 0.1C. Next, constant-current / constant-voltage charging was performed with a charging current of 0.1 C and a cut-off voltage of 3.75 V. The charge was terminated until the charging current reached 0.025 C. A 10-minute rest period was then provided. Subsequently, constant-current discharging was performed with a discharging current of 0.5 C and a cut-off voltage of 2.25 V. The percentage of the discharge capacity at a discharging current of 0.5 C relative to the discharge capacity at a discharging current of 0.1 C was calculated and used as the discharge capacity retention rate. Table 2 shows the discharge capacity retention rate of each all-solid-state energy storage element.

[0148] [Table 2]

[0149] As shown in Table 2, Example 1 and Comparative Examples 1 and 2, in which the positive electrode active material layer had a thickness of 80 μm or more, had higher discharge capacity densities than Comparative Examples 3 to 5. Among Example 1 and Comparative Examples 1 and 2, the initial coulombic efficiency and capacity retention rate during high-rate discharge of the all-solid-state energy storage element were higher in Example 1, in which the positive electrode active material layer did not contain a conductive agent, than in Comparative Examples 1 and 2, in which the positive electrode active material layer contained a conductive agent. Furthermore, although Comparative Example 3 did not contain a conductive agent, the initial coulombic efficiency and capacity retention rate during high-rate discharge were lower than those of Comparative Examples 4 and 5. From these findings, it is believed that the effect of increasing the initial coulombic efficiency and capacity retention rate during high-rate discharge by not containing a conductive agent is significantly achieved when the positive electrode active material layer thickness or discharge capacity density is large. [Industrial Applicability]

[0150] The present invention can be applied to electric storage elements used as power sources for electronic devices such as personal computers and communication terminals, and automobiles. [Explanation of symbols]

[0151] 1. Non-aqueous electrolyte energy storage element (all-solid-state energy storage element) 2 Positive electrode 3 negative electrode 4 isolation layer 5. Positive electrode substrate 6 Cathode active material layer 7. Negative electrode substrate 8 Negative electrode active material layer 20 Energy storage unit 30 Electricity storage device

Claims

1. a positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a solid electrolyte, and a binder, and is substantially free of a conductive agent; The positive electrode for a non-aqueous electrolyte storage element has a thickness of the positive electrode active material layer of 80 μm or more.

2. a positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a solid electrolyte, and a binder, and is substantially free of a conductive agent; The discharge capacity density per area of ​​the positive electrode active material layer is 4 mAh / cm ２ The positive electrode for a non-aqueous electrolyte electricity storage element is as described above.

3. 3. The positive electrode for a non-aqueous electrolyte storage element according to claim 1, wherein the content of the positive electrode active material in the positive electrode active material layer is 30% by volume or more.

4. 3. The positive electrode for a nonaqueous electrolyte storage element according to claim 1, wherein the content of said solid electrolyte in said positive electrode active material layer is 10% by volume or more.

5. 3. The positive electrode for a nonaqueous electrolyte storage element according to claim 1, wherein the total content of the positive electrode active material and the solid electrolyte in the positive electrode active material layer is 80% by volume or more.

6. 3. The positive electrode for a non-aqueous electrolyte storage element according to claim 1, wherein the positive electrode active material is a lithium transition metal composite oxide.

7. 3. The positive electrode for a nonaqueous electrolyte storage element according to claim 1, wherein the solid electrolyte is a sulfide solid electrolyte.

8. A non-aqueous electrolyte storage element comprising the positive electrode for a non-aqueous electrolyte storage element according to claim 1 or 2.

9. The nonaqueous electrolyte electricity storage element according to claim 8 , which is an all-solid-state electricity storage element.

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