Positive electrode active material, electrode and battery

Abstract

To mitigate the increase in resistance at the plateau boundary of the LMFP. The positive electrode active material includes an olivine-type lithium manganese iron phosphate. The olivine-type lithium manganese iron phosphate includes a dopant at the manganese iron site. At the manganese iron site, the dopant is "d Fe-X <d Mn-X " satisfies the relationship "d Fe-X " indicates the distance between the dopant and the nearest neighboring iron atoms. "d Mn-X " indicates the distance between the nearest neighbor atoms of the dopant and manganese.

Description

[Technical Field]

[0001] The present disclosure relates to a positive electrode active material, an electrode, and a battery. [Background technology]

[0002] WO 2016 / 158566 discloses lithium manganese phosphate nanoparticles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 158566 Summary of the Invention [Problem to be solved by the invention]

[0004] Olivine-type lithium manganese iron phosphate (LMFP) is being investigated as a positive electrode active material. The discharge curve of LMFP includes a Mn plateau due to the redox reaction of manganese (Mn) and an Fe plateau due to the redox reaction of iron (Fe). Because the voltage difference between the Mn plateau and the Fe plateau (hereinafter referred to as the "plateau gap") is large, a sudden increase in resistance (spike-like peak) tends to occur at the boundary between the Mn plateau and the Fe plateau (hereinafter referred to as the "plateau boundary") during charge and discharge.

[0005] The objective of the present disclosure is to mitigate the resistance rise at the plateau boundary of the LMFP. [Means for solving the problem]

[0006] The technical configuration and effects of the present disclosure will be described below. However, the mechanism of action includes speculation. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. One aspect of the present disclosure is a positive electrode active material. The positive electrode active material includes an olivine-type lithium manganese iron phosphate. The olivine-type lithium manganese iron phosphate includes a dopant at the manganese iron site. At the manganese iron site, the dopant is "d Fe-X <d Mn-X " satisfies the relationship "d Fe-X " indicates the distance between the dopant and the nearest neighboring iron atoms. "d Mn-X " indicates the distance between the nearest neighbor atoms of the dopant and manganese.

[0008] In the LMFP of the present disclosure, a dopant "X" is introduced into the MnFe site. In the MnFe site, the dopant is introduced closer to Fe than Mn. It is believed that the dopant is unevenly distributed on the Fe side, so that the Mn plateau remains substantially unchanged and the Fe plateau can rise. By reducing the gap between the plateaus, it is expected that the increase in resistance at the plateau boundary will be alleviated.

[0009] 2. The positive electrode active material described in the above item "1" may include, for example, the following configuration: The dopant includes an element whose valence can change between +I and +III.

[0010] Mn and Fe undergo a valence change between +II and +III. Elements that can change their valence between +I and +III may have suitable electrons between +II and +III.

[0011] 3. The positive electrode active material according to the above item "1" or "2" may include, for example, the following configuration: The dopant includes gallium.

[0012] Ga is an example of an element that can vary in valence between +I and +III.

[0013] 4. The positive electrode active material according to any one of the above items "1" to "3" may include, for example, the following configuration: The site occupancy rate of the dopant in the manganese iron site is 1% or more.

[0014] 5. The positive electrode active material described in the above item "4" may include, for example, the following configuration: The site occupancy rate of the dopant in the manganese iron site is 4% or more.

[0015] 6. The positive electrode active material described in the above item "5" may include, for example, the following configuration: The site occupancy rate of the dopant in the manganese iron site is 8% or more.

[0016] 7. The positive electrode active material according to any one of the above items "1" to "6" may include, for example, the following structure: Olivine-type lithium manganese iron phosphate is represented by the general formula "Li 1+a [(Mn 1-b Fe b ) 1-c X c ]PO4". In the general formula, "X" represents a dopant. The relationships "-0.5≦a≦0.5", "0.1≦b≦0.9" and "0.01≦c≦0.12" are satisfied.

[0017] For example, sites other than the MnFe site may be undoped.

[0018] 8. The positive electrode active material according to any one of the above items "1" to "7" may have the following configuration, for example: The discharge curve includes a Mn plateau resulting from a redox reaction of manganese and an Fe plateau resulting from a redox reaction of iron. The voltage difference between the Mn plateau and the Fe plateau is 0.5 V or less.

[0019] By keeping the gap between plateaus at 0.5 V or less, it is expected that the increase in resistance at the plateau boundary will be alleviated.

[0020] 9. One aspect of the present disclosure is an electrode. The electrode includes a positive electrode layer. The positive electrode layer includes the positive electrode active material described in any one of the above items "1" to "8".

[0021] The positive electrode layer can be alternatively referred to as a "positive electrode active material layer," a "positive electrode composite layer," etc. The "electrode" may be a "monopolar electrode (positive electrode)" or a "bipolar electrode" as long as it includes a positive electrode layer.

[0022] 10. One aspect of the present disclosure is a battery. The battery includes the electrode described in "9" above.

[0023] 11. The battery according to the above item "10" may include, for example, the following configuration: The battery has a bipolar structure.

[0024] A bipolar structure can be formed by stacking bipolar electrodes, in which the effects of the inter-plateau gap can be amplified due to the series connection of the cells.

[0025] Hereinafter, one embodiment of the present disclosure (hereinafter may be abbreviated as "this embodiment") and one example of the present disclosure (hereinafter may be abbreviated as "this example") will be described. However, this embodiment and this example do not limit the technical scope of the present disclosure. This embodiment and this example are illustrative in all respects. This embodiment and this example are non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is originally intended that any configurations may be extracted from this embodiment and arbitrarily combined. [Brief explanation of the drawings]

[0026] [Figure 1] 10 is a graph showing an example of a fitting result. [Figure 2] FIG. 1 is a conceptual diagram of a crystal structure. [Figure 3] FIG. 2 is a conceptual diagram of the atomic arrangement of MnFe sites in this embodiment. [Figure 4] 4A and 4B are diagrams illustrating a discharge curve and a resistance transition in the present embodiment. [Figure 5] 1 is a schematic perspective view of a battery according to an embodiment of the present invention. [Figure 6]FIG. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] 10 is a table showing experimental results. [Figure 8] 10 is a graph showing experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0027] Terms and phrases "Comprises," "includes," "has," and variations thereof are open-ended expressions. An open-ended structure may or may not further include additional elements in addition to the required elements. "Consists of" is a closed expression. However, even a closed structure may include additional elements that are normally associated impurities or unrelated to the subject technology. "Consists essentially of..." is a semi-closed expression. A semi-closed structure allows the addition of elements that do not substantially affect the basic and novel characteristics of the subject technology.

[0028] Expressions such as "may" and "may" are used in the permissive sense, meaning "to have the possibility," rather than in the obligatory sense, meaning "to have to."

[0029] Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and the like. For example, directions, angles, distances, and the like may be displaced relative to one another as long as substantially the same or similar functions are obtained. Geometric terms may include, for example, tolerances, errors, and the like in design, work, manufacturing, and the like. The dimensional relationships in each figure may not match the actual dimensional relationships. The dimensional relationships in each figure may be changed to aid the reader's understanding. For example, length, width, thickness, and the like may be changed. Some components may be omitted.

[0030] Elements described in the "singular" can also include the plural unless otherwise specified. For example, a particle can refer to a plurality of particles, a collection of particles, and a powder or granular material. Note that "a plurality of particles" can be alternatively expressed as "a group of particles."

[0031] Numerical ranges such as "m to n%" include the upper and lower limits unless otherwise specified. That is, "m to n%" indicates a numerical range of "m% or more and n% or less." Furthermore, "m% or more and n% or less" includes "more than m% and less than n%." "Equal to or more" and "equal to or less" are represented by inequality signs with an equal sign "≦, ≧." "More than" and "less than" are represented by inequality signs without an equal sign "<, >." A numerical value arbitrarily selected from within the numerical range may be used as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described elsewhere in this specification, in a table, a figure, or the like.

[0032] All numerical values ​​are modified by the term "about." The term "about" may mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​may be approximate values ​​that may vary depending on the application of the subject technology. All numerical values ​​may be expressed with significant figures. Unless otherwise specified, measured values ​​may be average values ​​of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. In general, the more measurements are made, the more reliable the average value is expected to be. Measured values ​​may be rounded to the nearest significant figure. Measured values ​​may include errors, such as those associated with the detection limits of the measuring device.

[0033] The devices, software, etc. used to measure various values ​​are merely examples. Products equivalent to the devices, etc. exemplified may also be used. When equivalent products are used, the measurement conditions may be adjusted to suit the device.

[0034] "D50" indicates the particle size at which the cumulative value reaches 50% in the volume-based particle size distribution (cumulative distribution). The volume-based particle size distribution is measured using a laser diffraction particle size distribution analyzer.

[0035] The "maximum Feret diameter" refers to the length of the long side of the minimum bounding rectangle (MBR) of a particle in a scanning electron microscope (SEM) or transmission electron microscope (TEM) image of the particle. Various dimensional measurements and shape analyses of SEM images and the like can be performed using, for example, image analysis software such as "ImageJ."

[0036] The chemical composition of the compound can be measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy). 0.1 g of a sample (e.g., a positive electrode active material) is dissolved in a mixed acid (10 ml) of hydrochloric acid and sulfuric acid to prepare a sample solution. The sample solution is diluted to an appropriate concentration using a measuring flask. After dilution, composition analysis is performed using an ICP-AES device. For example, a product named "PS3520 UVDD II (manufactured by Hitachi High-Tech Science Corporation)" may be used.

[0037] The stoichiometric composition formula indicates a representative example of a compound. The compound may have a non-stoichiometric composition. For example, "Al2O3" is not limited to a compound having a molar ratio of "Al / O=2 / 3". Unless otherwise specified, "Al2O3" indicates a compound containing Al and O in any molar ratio. For example, the compound may be doped with a trace element. A portion of the Al and O may be substituted with another element.

[0038] The introduction of the dopant into the MnFe site can be confirmed by the following procedure. Powder X-ray diffraction (XRD) measurement of the positive electrode active material is performed to obtain an XRD pattern. The XRD measurement conditions are, for example, as follows: Analysis method: Wide-angle method Measurement device: Smart Lab II (Rigaku Corporation) Measurement angle: 10° to 120° Tube:CuKα Tube voltage: 45kV Tube current: 200mA Measurement method: Continuous method Step: 0.02 IS:1 / 2 Speed: 2° / min RS: 20mm Detection mode: 1D

[0039] Rietveld analysis is performed on the XRD pattern using the software "GSAS-II." The structural model is in the space group Pnma. Background processing and structural refinement are performed on the XRD pattern. A variable is set for the w composition. This is generally performed within the range of "0≦w≦1." Then, the remainder of the added amount is used as a dopant for the MnFe site, and refinement of the lattice constant is performed, thereby calculating "Rwp," which is one of the refinement indices. A quadratic function "Rwp=aw 2 +bw+c" is fitted. Figure 1 is a graph showing an example of the fitting results. In the obtained fitted curve, the percentage of w that minimizes Rwp is considered to be the site occupancy of the dopant.

[0040] The distance between the dopant and the nearest neighboring atom, d Fe-X " and the nearest neighbor atomic distance between the dopant and Mn, "d Mn-X " can be identified by TEM-EDX (Transmission Electron Microscopy Energy Dispersive X-ray Spectroscopy).

[0041] The term "derivative" refers to a compound in which a part of a parent compound has been modified by at least one method selected from the group consisting of the introduction of a functional group, atomic substitution, oxidation, reduction, and other chemical reactions. The modification may be at one or more locations. The "substituent" may include at least one selected from the group consisting of, for example, alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, unsaturated cycloalkyl groups, aromatic groups, heterocyclic groups, halogen atoms (e.g., F, Cl, Br, I), OH groups, SH groups, CN groups, SCN groups, OCN groups, nitro groups, alkoxy groups, unsaturated alkoxy groups, amino groups, alkylamino groups, dialkylamino groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, acyloxy groups, aryloxycarbonyl groups, acylamino groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, sulfonylamino groups, sulfamoyl groups, carbamoyl groups, alkylthio groups, arylthio groups, sulfonyl groups, sulfinyl groups, ureido groups, phosphoric acid amide groups, sulfo groups, carboxy groups, hydroxamic acid groups, sulfino groups, hydrazino groups, imino groups, and silyl groups. These substituents may be further substituted. When there are two or more substituents, the substituents may be the same or different. A plurality of substituents may be bonded to each other to form a ring.

[0042] positive electrode active material FIG. 2 is a conceptual diagram of the crystal structure. The positive electrode active material includes olivine-type lithium manganese iron phosphate (LMFP). LMFP has a crystal structure belonging to the space group Pnma. The crystal structure can be identified by an XRD pattern. LMFP includes a Li site, a MnFe site, a P site, and an O site. LMFP includes a dopant "X" at the MnFe site. At the MnFe site, the dopant may be interstitial or substitutional. In the substitutional type, the dopant may substitute for Mn or Fe. As long as a dopant is introduced at the MnFe site, the other sites may be doped or may be undoped. Leaving sites other than the MnFe site undoped is expected to simplify the manufacturing process, for example.

[0043] FIG. 3 is a conceptual diagram of the atomic arrangement of the MnFe site in this embodiment. The dopant "X" is introduced near Fe. The nearest-neighbor atomic distance between the dopant and Fe, "d Fe-X ” is the distance between the dopant and Mn atoms nearest to each other, d Mn-X " is smaller than "d Fe-X <d Mn-X This is expected to result in a substantial change in the Mn plateau and an increase in the Fe plateau.

[0044] The distance between nearest neighbor atoms, d Mn-X ” to the nearest neighbor atomic distance “d Fe-X " ratio "d Fe-X / d Mn-X The ratio "d" may be, for example, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less. Fe-X / d Mn-X " may be, for example, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more.

[0045] The dopant may contain two or more elements, or may consist of one element. The fewer the types of dopants, the more likely it is that the manufacturing process will be simplified. The dopant may contain, for example, an element whose valence can change between +I and +III. The dopant may contain, for example, Ga. The transition between +I and +III is considered to be stable for Ga.

[0046] The site occupancy of the dopant at the MnFe site may be, for example, 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 15% or more, or 20% or more. The site occupancy of the dopant may be, for example, 30% or less, 20% or less, 15% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less.

[0047] LMFP can be, for example, a compound represented by the general formula "Li 1+a [(Mn 1-b Fe b ) 1-c X c ]PO4". In the general formula, the Li composition ratio "1+a" may satisfy, for example, the relationship "-0.5≦a≦0.5". "a" may be, for example, -0.4 or more, -0.3 or more, -0.2 or more, -0.1 or more, 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, or 0.4 or more. "a" may be, for example, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, 0 or less, -0.1 or less, -0.2 or less, -0.3 or less, or -0.4 or less.

[0048] In the above general formula, the Fe composition ratio "b" may satisfy the relationship of, for example, "0.1≦b≦0.9." The Fe composition ratio "b" may be, for example, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, or 0.8 or more. The Fe composition ratio "b" may be, for example, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0049] In the above general formula, "X" represents a dopant. X may be, for example, Ga. In the above general formula, the composition ratio "c" of the dopant may satisfy the relationship of, for example, "0.01≦c≦0.12." The composition ratio "c" of the dopant may be, for example, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.15 or more, or 0.20 or more. The dopant composition ratio "c" may be, for example, 0.30 or less, 0.20 or less, 0.15 or less, 0.12 or less, 0.11 or less, 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, or 0.01 or less.

[0050] FIG. 4 is an explanatory diagram of a discharge curve and resistance transition in this embodiment. The upper graph is a discharge curve. The lower graph is resistance transition. The horizontal axis of each graph is SOC (State of Charge). "SOC" indicates the percentage obtained by subtracting the percentage of the amount of electricity discharged from the fully charged state of the battery. An SOC of 100% indicates a fully charged state. An SOC of 0% indicates a fully discharged state. The vertical axis of the discharge curve is battery voltage [unit: V]. The vertical axis of the resistance transition is resistance [unit: Ω / cm 2 The conditions for measuring the discharge curve are, for example, as follows: Counter electrode: Li metal Electrolyte: LiPF6 (1M), EC / DMC=3 / 7 (volume ratio) Charge / discharge rate: 0.05C Charging voltage limit: 4.25V Discharge lower limit voltage: 3.0V

[0051] The discharge curve of an LMFP includes a Mn plateau and an Fe plateau. The Mn plateau is due to a redox reaction of Mn. The Fe plateau is due to a redox reaction of Fe. A "plateau" indicates a flat region of the discharge curve. For example, a region where the voltage change is 0.02 V or less with respect to a 10% change in SOC may be considered a plateau. The range (capacity) of each plateau may vary, for example, depending on the Fe composition ratio "b" in the general formula above. A "plateau voltage" indicates the intermediate voltage of the region considered to be a plateau. The voltage of the Mn plateau may be, for example, 4.00 V to 4.05 V.

[0052] In the example of FIG. 4, there is a plateau boundary "Boundary Division" between 40% and 60% SOC. Typically, the inter-plateau gap "ΔV" is about 0.60 V. As shown in the resistance transition, the resistance may increase spike-like at the plateau boundary. The introduction of dopants into the MnFe site may increase the Fe plateau. The increase in the Fe plateau may significantly mitigate the increase in resistance at the plateau boundary. The increase in the Fe plateau may result in an inter-plateau gap of, for example, 0.50 V or less. The inter-plateau gap may be, for example, 0.48 V or less, 0.46 V or less, 0.44 V or less, or 0.42 V or less. The inter-plateau gap may be, for example, 0.38 V or more, or 0.40 V or more.

[0053] In an undoped LMFP, the Fe plateau voltage is around 3.52 V. After doping, the Fe plateau voltage may be, for example, 3.54 V or more, 3.56 V or more, or 3.58 V or more. After doping, the Fe plateau voltage may be, for example, 3.62 V or less, or 3.60 V or less.

[0054] The LMFP may be, for example, in the form of a powder. The D50 of the LMFP may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more. The D50 of the LMFP may be, for example, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

[0055] The LMFP may form secondary particles. Secondary particles are aggregates of primary particles. "Primary particles" refer to particles that appear to have no grain boundaries in a two-dimensional image. The two-dimensional image may be, for example, a TEM image, an SEM image, or the like. The image magnification may be, for example, 10,000 to 30,000 times. The secondary particles may have any shape. The secondary particles may be, for example, spherical, rod-like, angular, or the like. Spherical secondary particles are expected to improve packing properties, for example. The sphericity of the secondary particles may be, for example, 0.85 or more, 0.90 or more, or 0.95 or more. The sphericity of the secondary particles may be, for example, 1 or less, 0.95 or less, or 0.90 or less. "Sphericity" refers to the circularity in an SEM image. The sphericity (circularity) is calculated using the following formula. The sphericity value is the arithmetic average of 30 secondary particles. ψ=4πS / L 2 ψ: Sphericity (circularity) π: Pi S: Cross-sectional area of ​​the particle (area of ​​the region enclosed by the particle outline) L: Particle perimeter (length of particle outline)

[0056] The primary particles may have any shape. The primary particles may be, for example, spherical, rod-like, angular, etc. The primary particles may be nanoparticles. The maximum Feret diameter of the primary particles may be, for example, 10 nm to 300 nm. The maximum Feret diameter of the primary particles may be, for example, 15 nm or more, 20 nm or more, 25 nm or more, 50 nm or more, 75 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, or 250 nm or more. The maximum Feret diameter of the primary particles may be, for example, 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, 75 nm or less, 50 nm or less, or 25 nm or less. The maximum Feret diameter of the primary particles represents the arithmetic average of 30 primary particles.

[0057] The surface of the primary particles may be coated with carbon. That is, a carbon layer or carbon coating may be formed on the surface of the primary particles. The carbon may coat a portion of the surface of the primary particles, or may coat the entire surface of the primary particles. The carbon may be derived from, for example, sugars. The amount of carbon attached may be, for example, 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, or 4% or more in mass fraction relative to the secondary particles. The amount of carbon attached may be, for example, 5% or less, 4% or less, or 3% or less in mass fraction relative to the secondary particles.

[0058] The positive electrode active material may further contain other components as long as it contains LMFP. The mixing ratio (mass ratio) of LMFP to other components may be, for example, "LMFP / other components = 9 / 1 to 1 / 9," "LMFP / other components = 8 / 2 to 2 / 8," "LMFP / other components = 7 / 3 to 3 / 7," or "LMFP / other components = 6 / 4 to 4 / 6." The positive electrode active material may be, for example, a mixture of LMFP powder and other component powders. The other component may include at least one selected from the group consisting of Li[NiCoMn]O2 (layered structure), Li[NiCoAl]O2 (layered structure), LiMnO2 (rock salt structure), and Li[NiMn]2O4 (spinel structure). Note that descriptions such as [NiCoMn] indicate that the sum of the compositional ratios in [ ] is 1. As long as the sum is 1, the components in [ ] may have any compositional ratio.

[0059] liquid battery In some of the present embodiments, the battery may be a liquid battery. "Liquid battery" refers to a battery containing an electrolyte. For example, a polymer battery is a liquid battery because it contains an electrolyte. In some of the present embodiments, the battery has a monopolar structure. In a monopolar structure, the power generating element may be wound or stacked. In some of the present embodiments, the battery has a bipolar structure. As an example, a battery having a bipolar structure (bipolar battery) will be described.

[0060] FIG. 5 is a schematic perspective view of a battery according to this embodiment. FIG. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. 5. Hereinafter, "plane-perpendicular direction" refers to the normal direction to the surface of a sheet-like member (e.g., foil, electrode, etc.). "In-plane direction" refers to any direction perpendicular to the plane-perpendicular direction. In the drawings of this embodiment, the Z-axis direction corresponds to the plane-perpendicular direction. The X-axis direction and the Y-axis direction are examples of in-plane directions.

[0061] The battery 100 includes an exterior body 90 and a power generating element 50. The exterior body 90 houses the power generating element 50. The exterior body 90 may include, for example, a first current collecting plate 91, a first laminate film 92, a second laminate film 93, and a second current collecting plate 94. The first laminate film 92 and the second laminate film 93 are joined to each other at their in-plane end portions. At the joint between the first laminate film 92 and the second laminate film 93, a sealant (not shown) may be interposed between the first laminate film 92 and the second laminate film 93.

[0062] The first current collector plate 91 and the second current collector plate 94 are joined to the power generating element 50 at their ends in the stacking direction (Z-axis direction). A first laminate film 92 is joined to the first current collector plate 91. A second laminate film 93 is joined to the second current collector plate 94. A sealant (not shown) may be interposed between the current collector plate and the laminate film at the joint between the current collector plate and the laminate film.

[0063] The power generating element 50 includes a plurality of bipolar electrodes 10. The plurality of bipolar electrodes 10 are stacked in the direction perpendicular to the plane (Z-axis direction). Each of the plurality of bipolar electrodes 10 includes a positive electrode layer 11, a current collecting foil 13, and a negative electrode layer 12, in this order, in the direction perpendicular to the plane. In the in-plane direction (e.g., the X-axis direction), the current collecting foil 13 extends outward relative to the positive electrode layer 11 and the negative electrode layer 12. For example, the current collecting foil 13 may extend outward relative to the positive electrode layer 11 and the negative electrode layer 12 over the entire periphery in the in-plane direction.

[0064] The current collecting foil 13 is a conductor. The current collecting foil 13 may include, for example, a metal foil, a conductive resin layer, or the like. For example, the current collecting foil 13 may be formed by laminating an Al foil and a Cu foil together. A carbon material may be applied to the surface of the current collecting foil 13. The carbon material may include, for example, carbon black, or the like.

[0065] The power generating element 50 includes a sealing material 30. The sealing material 30 is bonded to the current collecting foil 13 at an end in the in-plane direction. The sealing material 30 may be, for example, heat-welded to the current collecting foil 13. For example, the sealing material 30 may be disposed around the entire periphery in the in-plane direction. The sealing material may include, for example, a resin material. The sealing material 30 seals between adjacent current collecting foils 13 in the direction perpendicular to the surface. The sealing material 30 seals between the current collecting foils 13, thereby dividing them into cells 40. A cell 40 is the smallest unit of the power generating element 50. The battery 100 includes multiple cells 40, and may therefore also be referred to as a "bipolar module." Each of the multiple cells 40 is sealed. The multiple cells 40 are isolated from one another. Each of the multiple cells 40 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte.

[0066] Positive electrode layer The positive electrode layer 11 is attached to one surface of the current collector foil 13. For example, the positive electrode layer 11 may have a groove formed therein. For example, the positive electrode layer 11 may be formed in a striped pattern. The positive electrode layer 11 includes a positive electrode active material. That is, the battery 100 includes the positive electrode active material. Details of the positive electrode active material are as described above.

[0067] The positive electrode layer 11 may further contain, in addition to the positive electrode active material, for example, a conductive material and a binder. The amount of the conductive material may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the positive electrode active material. The conductive material may contain any component. For example, the conductive material may contain at least one material selected from the group consisting of graphite, acetylene black (AB), Ketjen Black (registered trademark), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes (GF).

[0068] The amount of binder may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the positive electrode active material. The binder may contain any component. For example, the binder may contain at least one selected from the group consisting of polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyoxyethylene alkyl ether, and derivatives thereof.

[0069] The positive electrode layer 11 may further contain, for example, an inorganic filler, an organic filler, a solid electrolyte, a surface modifier, a dispersant, a lubricant, a flame retardant, a protective agent, a flux, a coupling agent, an adsorbent, etc. The positive electrode layer may also contain, for example, polyoxyethylene allyl phenyl ether phosphate, zeolite, a silane coupling agent, MoS2, WO3, etc.

[0070] negative electrode layer The negative electrode layer 12 is attached to one surface of the current collector foil 13. The negative electrode layer 12 is disposed on the back side of the positive electrode layer 11. The negative electrode layer 12 may have a larger area than the positive electrode layer 11. The negative electrode layer 12 includes a negative electrode active material.

[0071] The negative electrode active material may be, for example, in the form of particles or a sheet. The D50 of the negative electrode active material may be, for example, 1 μm or more, 5 μm or more, or 10 μm or more. The D50 of the negative electrode active material may be, for example, 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

[0072] The negative electrode active material may include any component. For example, the negative electrode active material may include at least one selected from the group consisting of a carbon-based active material, an alloy-based active material, a Si-C composite material, Li metal, a Li-based alloy, and lithium titanate. In some embodiments of the present invention, the battery may be a Li metal negative electrode battery.

[0073] The carbon-based active material may contain, for example, at least one selected from the group consisting of graphite, soft carbon, and hard carbon. "Graphite" is a general term for natural graphite and artificial graphite. The graphite may be a mixture of natural graphite and artificial graphite. The mixing ratio (mass ratio) may be, for example, "natural graphite / artificial graphite = 1 / 9 to 9 / 1", "natural graphite / artificial graphite = 2 / 8 to 8 / 2", or "natural graphite / artificial graphite = 3 / 7 to 7 / 3".

[0074] The surface of the graphite may be coated with, for example, amorphous carbon. The surface of the graphite may be coated with, for example, a different material. The different material may contain, for example, at least one selected from the group consisting of P, W, Al, and O. The different material may contain, for example, at least one selected from the group consisting of Al(OH)3, AlOOH, Al2O3, WO3, Li2CO3, LiHCO3, and Li3PO4.

[0075] The alloy-based active material may contain, for example, at least one selected from the group consisting of Si, Li silicate, SiO, Si-based alloy, tin (Sn), SnO, and Sn-based alloy.

[0076] SiO may have a composition represented by, for example, the general formula "SiO x ". In the general formula, for example, the relationship of "0 < x < 2", "0.5 ≤ x ≤ 1.5", or "0.8 ≤ x ≤ 1.2" may be satisfied.

[0077] "Si-C composite material" refers to a composite material of a carbon-based active material (such as graphite) and an alloy-based active material (such as Si). For example, Si fine particles may be dispersed in carbon particles. For example, Si fine particles may be dispersed in graphite particles. For example, Li silicate particles may be coated with a carbon material (such as amorphous carbon).

[0078] Separator The separator 20 can separate the positive electrode layer 11 from the negative electrode layer 12. The separator 20 has electrical insulation properties. The separator 20 may include, for example, at least one selected from the group consisting of a resin film (polymer film), an inorganic particle layer, and an organic particle layer. The separator 20 may include, for example, a resin film and an inorganic particle layer.

[0079] The resin film is porous. The resin film may include, for example, a microporous film, a nonwoven fabric, etc. The resin film includes a resin skeleton. The resin skeleton may be continuous, for example, in a network form. Pores are formed in the gaps in the resin skeleton. The resin film is permeable to an electrolyte solution. The resin film may have, for example, an average pore diameter of 1 μm or less. The average pore diameter of the resin film may be, for example, 0.01 to 1 μm, or 0.1 to 0.5 μm. The "average pore diameter" can be measured by mercury intrusion porosimetry. The Gurley value of the resin film is, for example, 50 to 250 s / 100 cm. 3 The "Gurley value" can be measured by the Gurley test method.

[0080] The resin film may contain at least one selected from the group consisting of, for example, olefin-based resins, polyurethane-based resins, polyamide-based resins, cellulose-based resins, polyether-based resins, acrylic-based resins, and polyester-based resins. The resin film may contain at least one selected from the group consisting of, for example, polyethylene (PE), polypropylene (PP), polyamide (PA), polyamideimide (PAI), polyimide (PI), aromatic polyamide (aramid), polyphenylene ether (PPE), and derivatives thereof. The resin film may be formed by, for example, a stretching method, a phase separation method, or the like. The thickness of the resin film may be, for example, 5 to 50 μm, or 10 to 25 μm.

[0081] The resin film may have, for example, a single-layer structure. The resin film may be composed of, for example, a PE layer. The skeleton of the PE layer is formed of PE. The PE layer may have a shutdown function. The resin film may have, for example, a multi-layer structure. The resin film may include, for example, a PP layer and a PE layer. The skeleton of the PP layer is formed of PP. The resin film may have, for example, a three-layer structure. The resin film may be formed by laminating, for example, a PP layer, a PE layer, and a PP layer in this order. The thickness of the PE layer may be, for example, 5 to 20 μm. The thickness of the PP layer may be, for example, 3 to 10 μm.

[0082] The inorganic particle layer may be formed on the surface of the resin film. The inorganic particle layer may be formed on only one side of the resin film, or on both sides. The inorganic particle layer may be formed on the surface facing the positive electrode layer 11, or on the surface facing the negative electrode layer 12. The inorganic particle layer may be formed on the surface of the positive electrode layer 11, or on the surface of the negative electrode layer 12.

[0083] The inorganic particle layer is porous. The inorganic particle layer contains inorganic particles. The inorganic particles may also be referred to as "inorganic filler." Pores are formed in the gaps between the inorganic particles. The thickness of the inorganic particle layer may be, for example, 0.5 to 10 μm, or 1 to 5 μm. The inorganic particles may contain, for example, a heat-resistant material. An inorganic particle layer containing a heat-resistant material is also referred to as an "HRL (Heat Resistance Layer)." The inorganic particles may contain at least one selected from the group consisting of boehmite, alumina, zirconia, titania, magnesia, silica, and the like. The inorganic particles may have any shape. The inorganic particles may be, for example, spherical, rod-like, plate-like, fibrous, or the like. The D50 of the inorganic particles may be, for example, 0.1 to 10 μm, or 0.5 to 3 μm. The inorganic particle layer may further contain a binder. The binder may contain, for example, at least one selected from the group consisting of acrylic resins, polyamide resins, fluorine resins, aromatic polyether resins, and liquid crystal polyester resins.

[0084] The separator 20 may include, for example, an organic particle layer. The separator 20 may include, for example, an organic particle layer instead of a resin film. The separator 20 may include, for example, an organic particle layer instead of an inorganic particle layer. The separator 20 may include both a resin film and an organic particle layer. The separator 20 may include both an inorganic particle layer and an organic particle layer. The separator 20 may include a resin film, an inorganic particle layer, and an organic particle layer.

[0085] The thickness of the organic particle layer may be, for example, 0.1 to 50 μm, 0.5 to 20 μm, 0.5 to 10 μm, or 1 to 5 μm. The organic particle layer contains organic particles. The organic particles may also be referred to as "organic filler." The organic particles may contain a heat-resistant material. The organic particles may include, for example, at least one selected from the group consisting of PE, PP, PTFE, PI, PAI, PA, and aramid. The organic particles may be, for example, spherical, rod-like, plate-like, fibrous, or the like. The D50 of the organic particles may be, for example, 0.1 to 10 μm, or 0.5 to 3 μm.

[0086] Separator 20 may include, for example, a mixed layer, which includes both inorganic and organic particles.

[0087] electrolyte The electrolyte is a liquid electrolyte. The electrolyte includes a solute and a solvent. The concentration of the solute may be, for example, 0.5 to 1 mol / L, 1 to 1.5 mol / L, 1.5 to 2 mol / L, 2 to 2.5 mol / L, or 2.5 to 3 mol / L. "mol / L" may also be written as "M." The solute includes a supporting salt (Li salt). The solute may include, for example, an inorganic acid salt, an imide salt, an oxalate complex, a halide, etc. The solute may include, for example, at least one selected from the group consisting of LiPF6, LiBF4, LiClO4, LiAsF6, LiSbF6, LiN(SO2F)2 "LiFSI", LiN(SO2CF3)2 "LiTFSI", LiB(C2O4)2 "LiBOB", LiBF2(C2O4) "LiDFOB", LiPF2(C2O4)2 "LiDFOP", LiPO2F2, FSO3Li, LiI, LiBr, and derivatives thereof.

[0088] The electrolytic solution may contain, for example, a carbonate-based solvent (carbonate ester-based solvent). The solvent may contain, for example, a cyclic carbonate, a chain carbonate, a fluorinated carbonate, or the like. The solvent may contain, for example, at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (FEC), difluoroethylene carbonate, 4,4-difluoroethylene carbonate, trifluoroethylene carbonate, perfluoroethylene carbonate, fluoropropylene carbonate, difluoropropylene carbonate, and derivatives thereof.

[0089] The solvent may contain a cyclic carbonate (EC, PC, FEC, etc.) and a chain carbonate (EMC, DMC, DEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate to the chain carbonate may be, for example, "cyclic carbonate / chain carbonate = 1 / 9 to 4 / 6," "cyclic carbonate / chain carbonate = 2 / 8 to 3 / 7," or "cyclic carbonate / chain carbonate = 3 / 7 to 4 / 6."

[0090] The solvent may contain a cyclic carbonate (EC, PC, etc.) and a fluorinated cyclic carbonate (FEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate to the fluorinated cyclic carbonate may be, for example, "cyclic carbonate / fluorinated cyclic carbonate = 99 / 1 to 90 / 10," "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 1 / 9," "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 7 / 3," or "cyclic carbonate / fluorinated cyclic carbonate = 3 / 7 to 1 / 9."

[0091] The solvent may include, for example, EC, FEC, EMC, DMC, and DEC. The volume ratio of each component may be determined, for example, by the relationship "V EC +V FEC +V EMC +V DMC +V DEC =10". In the relational expression, "V EC , V FEC , V EMC , V DMC , V DEC " indicates the volume ratio of EC, FEC, EMC, DMC, and DEC, respectively. "1≦V EC ≦4", 0≦V FEC ≦3", "V EC +V FEC ≦4", 0≦V EMC ≦9", 0≦V DMC ≦9", 0≦V DEC ≦9", "6≦V EMC +V DMC +V DEC ≦9". For example, "1≦V EC ≦2” or “2≦VEC ≦3". For example, the relationship "1 ≦ V FEC ≦2” or “2≦V FEC ≦4". For example, the relationship "3≦V EMC ≦4” or “6≦V EMC ≦8". For example, the relationship "3≦V DMC ≦4” or “6≦V DMC ≦8". For example, the relationship "3≦V DEC ≦4” or “6≦V DEC ≦8" may be satisfied.

[0092] The solvent may have a composition, for example, in volume ratios of "EC / EMC=3 / 7," "EC / DMC=3 / 7," "EC / FEC / DEC=1 / 2 / 7," "EC / DMC / EMC=3 / 4 / 3," "EC / DMC / EMC=3 / 3 / 4," "EC / FEC / DMC / EMC=2 / 1 / 4 / 3," "EC / FEC / DMC / EMC=1 / 2 / 4 / 3," "EC / FEC / DMC / EMC=2 / 1 / 3 / 4," or "EC / FEC / DMC / EMC=1 / 2 / 3 / 4."

[0093] The electrolyte may contain an ether-based solvent, such as at least one selected from the group consisting of tetrahydrofuran (THF), 1,4-dioxane (DOX), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), hydrofluoroether (HFE), ethylglyme, triglyme, tetraglyme, and derivatives thereof.

[0094] The electrolyte may contain any additive. The amount of additive (mass fraction relative to the total amount of the electrolyte) may be, for example, 0.01 to 5%, 0.05 to 3%, or 0.1 to 1%. The additive may include, for example, an SEI (Solid Electrolyte Interphase) formation promoter, an SEI formation inhibitor, a gas generating agent, an overcharge inhibitor, a flame retardant, an antioxidant, an electrode protectant, a surfactant, etc.

[0095] Examples of the additives include vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), tert-amylbenzene, 1,4-di-tert-butylbenzene, biphenyl (BP), cyclohexylbenzene (CHB), ethylene sulfite (ES), ethylene sulfate (DTD), γ-butyrolactone, phosphazene compounds, carboxylic acid esters (e.g., methyl formate (MF), methyl acetate (MA), methyl propionate (MP), diethyl malonate (DEM), etc.), fluorobenzenes (e.g., monofluorobenzene (FB), 1,2-difluoropropane (DEM), etc.), and the like. fluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene, 1,2,3,4-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene, 1,2,4,5-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, etc.), fluorotoluenes (e.g., 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2,3-difluorotoluene, 2,4-difluorotoluene, 2,5-difluorotoluene, 2,6-difluorotoluene, 3,4-difluorotoluene, octafluorotoluene, etc.), benzotrifluorides (e.g., benzotrifluoride, 2-fluorobenzotrifluoride, 3-fluorobenzotrifluoride, 4-fluorobenzotrifluoride, 2-methylbenzotrifluoride, 3-methylbenzotrifluoride, 4-methylbenzotrifluoride, etc.), fluoroxylenes (e.g., 3-fluoro-o-xylene, 4-fluoro-o-xylene, 2-fluoro-m-xylene, 5-fluoro-m-xylene, etc.), sulfur-containing heterocyclic compounds (e.g., benzothiazole, 2-methylbenzotrifluoride, The solvent may contain at least one selected from the group consisting of benzotriazole, benzotriazole, tetrathiafulvalene, etc.), nitrile compounds (e.g., adiponitrile, succinonitrile, etc.), phosphate esters (e.g., trimethyl phosphate, triethyl phosphate, etc.), carboxylic acid anhydrides (e.g., acetic anhydride, propionic anhydride, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride, etc.), alcohols (e.g., methanol, ethanol, n-propyl alcohol, ethylene glycol, diethylene glycol monomethyl ether, etc.), and derivatives thereof.

[0096] The components described above as solutes and solvents may be used as minor components (additives). The additives may include, for example, at least one selected from the group consisting of LiBF, LiFSI, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPOF, FSOLi, LiI, LiBr, HFE, DOX, PC, FEC, and derivatives thereof.

[0097] The electrolyte solution may contain an ionic liquid, which may include, for example, at least one selected from the group consisting of sulfonium salts, ammonium salts, pyridinium salts, piperidinium salts, pyrrolidinium salts, morpholinium salts, phosphonium salts, imidazolium salts, and derivatives thereof.

[0098] In some embodiments of the present invention, the battery may include a gel electrolyte. That is, the battery may be a polymer battery. The gel electrolyte may include an electrolyte solution and a polymer material. The polymer material may form a polymer matrix. The polymer material may include, for example, at least one selected from the group consisting of PVdF, PVdF-HFP, polyacrylonitrile (PAN), PVdF-PAN, polyethylene oxide (PEO), polyethylene glycol (PEG), and derivatives thereof.

[0099] All solid state battery In some embodiments of the present invention, the battery may be an all-solid-state battery. The all-solid-state battery may have a bipolar structure. The all-solid-state battery includes a solid electrolyte instead of the electrolyte solution and the separator 20. The solid electrolyte may also be included in the positive electrode layer 11 and the negative electrode layer 12. Instead of the separator 20, a solid electrolyte layer separates the positive electrode layer 11 from the negative electrode layer 12. The solid electrolyte layer includes, for example, a solid electrolyte and a binder.

[0100] The solid electrolyte may be, for example, a powder. The D50 of the solid electrolyte may be, for example, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, or 1 μm or more. The D50 of the solid electrolyte may be, for example, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less.

[0101] The solid electrolyte may include, for example, at least one selected from the group consisting of a sulfide solid electrolyte, a halide solid electrolyte, an oxide solid electrolyte, a hydride solid electrolyte, and a nitride solid electrolyte.

[0102] The sulfide solid electrolyte may contain at least one phase selected from the group consisting of an amorphous phase, a crystalline phase, and a glass ceramic (crystallized glass) phase. The crystalline phase may be, for example, an argyrodite type or an LGPS type. The sulfide solid electrolyte contains Li and sulfur (S). The sulfide solid electrolyte may further contain any optional component in addition to Li and S.

[0103] Examples of sulfide solid electrolytes include LiI-LiBr-Li3PS4, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2O-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-GeS2-P2S5, Li2S-P2S5, and Li 10 GeP2S 12 , Li4P2S6, Li7P3S 11 , Li3PS4, and Li7PS6.

[0104] For example, "LiI-LiBr-Li3PS4" indicates a sulfide solid electrolyte produced by mixing LiI, LiBr, and Li3PS4 in an arbitrary ratio by mass. For example, the sulfide solid electrolyte may be produced by a mechanochemical method. The mixing ratio may be specified by adding a number before each raw material. For example, "10LiI-15LiBr-75Li3PS4" indicates that the mixing ratio is "LiI / LiBr / Li3PS4=10 / 15 / 75 (mass ratio)."

[0105] The sulfide solid electrolyte may have a composition represented by the general formula "xLiS-(1-x)P2S5." In the general formula, "x" may be, for example, greater than 0, 0.1 or greater, 0.2 or greater, 0.25 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.75 or greater, 0.8 or greater, or 0.9 or greater. "x" may be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.75 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. For example, when "x=0.75," "xLiS-(1-x)P2S5" may have a composition of Li3PS4.

[0106] The sulfide solid electrolyte may have a composition represented by the general formula "yLiI-zLiBr-(100-yz)[xLi2S-(1-x)P2S5]". In the general formula, "x" may be, for example, 0.5 or more, 0.6 or more, 0.7 or more, 0.75 or more, 0.8 or more, or 0.9 or more. "x" may be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.75 or less, 0.7 or less, or 0.6 or less. "y" may be, for example, 0 or more, 5 or more, 10 or more, 15 or more, 20 or more, or 25 or more. "y" may be, for example, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less. "z" may be, for example, 0 or more, 5 or more, 10 or more, 15 or more, 20 or more, or 25 or more. "z" may be, for example, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less.

[0107] The sulfide solid electrolyte is, for example, represented by the general formula "Li 7-x-2y PS 6-x-y X y In the general formula, the relationships "0<7-x-2y", "0<6-xy", "0≦x", and "0≦y" are satisfied. "X" may include, for example, at least one element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0108] The sulfide solid electrolyte is, for example, represented by the general formula "Li4-x M 1-x P x It may have a composition represented by S4. In the general formula, "x" may be, for example, greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more. "x" may be, for example, less than 1, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. "M" may contain, for example, at least one selected from the group consisting of Al, Zn, In, Ge, Si, Sn, Sb, Ga, and Bi.

[0109] The sulfide solid electrolyte may have, for example, a composition represented by the general formula "Li 10+x Ge 1+x P 2-x S 12 ". In the general formula, "x" may be, for example, 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, or 0.6 or more. "x" may be, for example, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. The sulfide solid electrolyte represented by the above general formula may contain, for example, an LGPS-type crystal phase.

[0110] The halide solid electrolyte may have, for example, a composition represented by the general formula "Li 6-na M a X6". In the general formula, "n" indicates the oxidation number of "M". "M" may contain, for example, an atom having an oxidation number of +3. "M" may contain, for example, an atom having an oxidation number of +4. "M" may contain, for example, at least one selected from the group consisting of Y, Al, Ti, Zr, Ca, and Mg. For example, the relationship of "0 < a < 2" may be satisfied. "X" may contain, for example, at least one selected from the group consisting of F, Cl, Br, and I.

[0111] The halide solid electrolyte may have, for example, a composition represented by the general formula "Li 3-a Tia Al 1-a F6". In the general formula, "a" may be, for example, 0 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more. "a" may be, for example, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0112] The halide solid electrolyte is, for example, a compound represented by the general formula "Li3YCl a Br b I 6-a-b " In the general formula, for example, the relationship "0≦a+b≦6" may be satisfied. "a" may be, for example, 0 or more, 1 or more, 2 or more, 3 or more, 4 or more, or 5 or more. "a" may be, for example, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less. "b" may be, for example, 0 or more, 1 or more, 2 or more, 3 or more, 4 or more, or 5 or more. "b" may be, for example, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less.

[0113] The oxide solid electrolyte is, for example, LiNbO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, La 2 / 3-x Li 3x TiO3 and Li7La3Zr2O 12 The hydride solid electrolyte may contain, for example, LiBH4, etc. The nitride solid electrolyte may contain, for example, Li3N, Li3BN2, etc. [Example]

[0114] LMFP production The experimental results are shown in a table in Figure 7. Various LMFPs with different site occupancies of the dopant (Ga) were fabricated according to the following procedure.

[0115] Manganese carbonate, ferric phosphate, and lithium hydroxide are weighed out to achieve the desired composition ratio of Mn, Fe, and P. Manganese carbonate, ferric phosphate, and lithium hydroxide are stirred and mixed in water to form a slurry. The slurry is spray-dried to form a first precursor (powder). A mixture of the first precursor and a predetermined amount of dopant source (gallium nitrate) is subjected to a first firing in a nitrogen atmosphere. The first firing is performed at a low temperature of 400°C for 24 to 48 hours to accommodate Ga, which has a low melting point. Gallium nitrate is thought to become more reactive near its decomposition temperature of 400°C. After the first firing, a second firing is performed at 650°C in a nitrogen atmosphere to produce LMFP. The LMFP is pulverized in a planetary ball mill.

[0116] evaluation The discharge curves and resistance transitions were measured for various LMFPs.

[0117] Experimental results In Figure 7, the peak resistance tends to decrease as the Ga site occupancy rate increases. Figure 8 is a graph showing the experimental results. Figure 8 shows the discharge curves and resistance transitions for Ga(0%) and Ga(12%). Compared to Ga(0%), the plateau gap was reduced by 12% for Ga(12%). Furthermore, the peak resistance improved by 16.2% for Ga(12%) compared to Ga(0%). [Explanation of symbols]

[0118] 10 bipolar electrode, 11 positive electrode layer, 12 negative electrode layer, 13 current collecting foil, 20 separator, 30 sealing material, 40 cell, 50 power generating element, 90 exterior body, 91 first current collecting plate, 92 first laminate film, 93 second laminate film, 94 second current collecting plate, 100 battery.

Claims

1. Contains olivine-type lithium manganese iron phosphate, The olivine-type lithium manganese iron phosphate contains a dopant at the manganese iron site, the site occupancy of the dopant at the manganese iron site is greater than 1%; the dopant comprises gallium; In the manganese ferrosite, The dopant is d Fe-X <d Mn-X Fulfilling the relationship, The above d Fe-X represents the distance between the dopant and the nearest neighboring atoms of iron, and The above d Mn-X represents the distance between the dopant and manganese atoms nearest to each other, Cathode active material.

2. a site occupancy rate of the dopant at the manganese iron site is more than 1% and not more than 12%; The positive electrode active material according to claim 1 .

3. The site occupancy rate is 4% or more. The positive electrode active material according to claim 2 .

4. The site occupancy rate is 8% or more. The positive electrode active material according to claim 3 .

5. The olivine-type lithium manganese iron phosphate has the general formula: Li 1+a [(Mn 1-b Fe b ) 1-c X c ]OO 4 and having a composition represented by In the general formula, X represents the dopant, and the relationships of −0.5≦a≦0.5, 0.1≦b≦0.9, and 0.01<c≦0.12 are satisfied. The positive electrode active material according to claim 1 or 2.

6. The discharge curve includes a Mn plateau due to a manganese redox reaction and an Fe plateau due to an iron redox reaction, and a voltage difference between the Mn plateau and the Fe plateau is 0.5 V or less; The positive electrode active material according to claim 1 or 2.

7. a positive electrode layer, and The positive electrode layer contains the positive electrode active material according to claim 1 or 2. electrode.

8. 8. The electrode of claim 7, battery.

9. having a bipolar structure, The battery of claim 8.

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