Positive electrode active material, electrode, and battery

Abstract

Improved output characteristics. [Solution] The positive electrode active material has a crystal structure that belongs to the space group Pnma. The X-ray diffraction pattern is "5.8 ≤ I (200) / I (020) The relationship "I (200) " indicates the integrated intensity of the 200 diffraction peak. (020) This indicates the integrated intensity of the 020 diffraction peak.

Description

[Technical Field]

[0001] This disclosure relates to positive electrode active materials, electrodes, and batteries. [Background technology]

[0002] International Publication No. 2016 / 158566 concerns the peak intensity ratio of X-ray diffraction I 20 / I 29 We disclose lithium manganese phosphate nanoparticles having a coefficient of 0.88 or higher and a crystallite size of 10 nm or higher and a crystallite size of 50 nm or lower. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2016 / 158566 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Olivine-type cathode active materials have been proposed. These materials possess a crystal structure (olivine-type structure) that belongs to the space group Pnma. Conventionally, methods have been proposed to increase discharge capacity by, for example, controlling the orientation of primary particles. However, there is room for improvement in output characteristics.

[0005] The purpose of this disclosure is to improve output characteristics. [Means for solving the problem]

[0006] The technical configuration and effects of this disclosure are described below. However, the mechanism of action includes assumptions. The mechanism of action does not limit the technical scope of this disclosure.

[0007] 1. One aspect of this disclosure is a positive electrode active material. The positive electrode active material has a crystal structure assigned to the space group Pnma. The X-ray diffraction pattern is "5.8 ≤ I (200) / I(020) satisfies the relationship of "I". (200) "I" represents the integrated intensity of the 200 diffraction peak. (020) "I" represents the integrated intensity of the 020 diffraction peak.

[0008] In the olivine-type structure, Li is considered to diffuse in the b-axis direction. The b-axis is parallel to the 200 plane and perpendicular to the 020 plane. In the X-ray diffraction (XRD) pattern, the intensity ratio "I" of the 200 diffraction peak to the 020 diffraction peak (200) / I (020) " is considered to be related to the b-axis orientation of the crystal structure. When the relationship of "5.8 ≤ I (200) / I (020) " is satisfied, an improvement in output characteristics is expected. It is considered that due to a stronger b-axis orientation compared to the prior art, the sites where Li can enter and exit the crystallites increase.

[0009] 2. The positive electrode active material described in "1" above may include, for example, the following configuration. The X-ray diffraction pattern satisfies the relationship of "I (200) / I (020) ≤ 16.8".

[0010] 3. The positive electrode active material described in "2" above may include, for example, the following configuration. The X-ray diffraction pattern satisfies the relationship of "I (200) / I (020) ≤ 14.6".

[0011] <​​​​​​​​​​​​​​​​5. The positive electrode active material described in "4" above may include, for example, the following configuration: The positive electrode active material has a crystallite size of 1540 Å or less.

[0015] When the crystallite size is 1540 Å or less, an improvement in output characteristics can be expected.

[0016] 6. The positive electrode active material described in any one of items "1" to "5" above may include, for example, the following configuration: The positive electrode active material includes at least one selected from the group consisting of lithium manganese phosphate and lithium iron manganese phosphate.

[0017] Lithium iron phosphate (LFP) is known as an olivine-type cathode active material. Lithium manganese phosphate (LMP) and lithium iron manganese phosphate (LMFP) can have higher plateau potentials compared to LFP. LMP and LMFP are considered advantageous for high power output. However, LMP and LMFP also have the disadvantage of lower electronic conductivity compared to LFP. Further improvement in the power characteristics of LMP and LMFP is needed. The crystal structure of this disclosure is considered suitable for LMP and LMFP.

[0018] 7. One aspect of the present disclosure is an electrode. The electrode includes a positive electrode layer. The positive electrode layer includes a positive electrode active material as described in any one of the above items "1" to "6".

[0019] The positive electrode layer can be referred to as the "positive electrode active material layer," "positive electrode composite layer," etc. The "electrode" may be a "monopolar electrode (positive electrode)" or a "bipolar electrode," as long as it includes the positive electrode layer.

[0020] 8. One aspect of this disclosure is a battery, which includes the electrodes described in "7" above.

[0021] 9. The battery described in "8" above may include, for example, the following configuration: The battery has a bipolar structure.

[0022] A bipolar structure can be formed by stacking bipolar electrodes. This bipolar structure is expected to improve, for example, output characteristics.

[0023] Hereinafter, one embodiment of the present disclosure (which may be abbreviated as "this embodiment") and one example of the present disclosure (which may be abbreviated as "this example") will be described. However, this embodiment and this example will 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 not restrictive. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the claims. For example, it is intended from the outset that any configuration may be extracted from this embodiment and combined in any way. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic perspective view of the battery in this embodiment. [Figure 2] This is a schematic cross-sectional view along the line II-II in Figure 1. [Figure 3] This is a table showing the experimental results. [Figure 4] This graph shows the relationship between the intensity ratio "I(200) / I(020)" and the IV resistance. [Figure 5] This graph shows the relationship between crystallite size "D" and IV resistance. [Modes for carrying out the invention]

[0025] Terms, phrases "Equipped with," "includes," "possesses," and variations thereof are open-ended expressions. Configurations expressed in an open-ended manner may or may not include additional elements in addition to the essential elements. The statement "consists of" is a closed expression. However, even configurations expressed in a closed manner may include additional elements that are usually incidental impurities or irrelevant to the subject technology. The statement "substantially consists of..." is a semi-closed expression. In configurations expressed in a semi-closed manner, the addition of elements that do not substantially affect the basic and novel characteristics of the subject technology is permitted.

[0026] Expressions such as "may do" and "may be" are used in a permissive sense, meaning "there is a possibility," rather than in an obligatory sense, meaning "it must be done."

[0027] Geometric terms should not be interpreted strictly. Examples of geometric terms include "parallel," "perpendicular," and "orthogonal." For example, direction, angle, distance, etc., may be relatively distorted within a range where substantially the same or similar function is obtained. Geometric terms may include tolerances, errors, etc., in design, operation, and manufacturing. Dimensional relationships in each figure may not match actual dimensional relationships. Dimensional relationships in each figure may be modified to aid the reader's understanding. For example, length, width, thickness, etc., may be changed. Some components may be omitted.

[0028] Elements described in the singular form may also include plural forms unless otherwise specified. For example, "particle" may refer to multiple particles, a collection of particles, or a granular material. Note that "multiple particles" can be rephrased as "group of particles."

[0029] Numerical ranges such as "m to n%" include upper and lower limits unless otherwise specified. That is, "m to n%" indicates a numerical range of "m% or more and n% or less". Also, "m% or more and n% or less" includes "greater than m% and less than n%". "Greater than or equal to" and "less than or equal to" are represented by the equals sign inequality signs "≦" and "≧". "Greater than" and "less than" are represented by the inequality signs without an equals sign "<" and ">". A number 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 number within the numerical range with a number listed in another part of this specification, in a table, in a figure, etc.

[0030] All numerical values ​​are modified by the term "approximately." The term "approximately" can mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​may be approximations that can vary depending on the application of the technology in question. All numerical values ​​may be expressed with significant figures. Unless otherwise specified, measured values ​​may be the average of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. Generally, the more measurements taken, 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.

[0031] The devices, software, etc., used for measuring various values ​​are merely examples. Equivalent devices may be used. If equivalent devices are used, the measurement conditions may be adjusted to suit the device.

[0032] Intensity ratio “I (200) / I (020) The following procedure identifies the positive electrode active material. First, the XRD pattern of the positive electrode active material is obtained. Powder XRD measurement can be performed, for example, under the following conditions. Analysis method: Wide-angle method Measurement device: Smart Lab II (manufactured by Rigaku Corporation) Measurement angle: 10° to 120° Tube:CuKα Tube voltage: 45kV Tube current: 200mA Measurement method: Continuous method Step: 0.02 Speed: 2° / min IS:1 / 2 RS: 20mm Detection mode: 1D

[0033] The XRD pattern is subjected to background processing. The space group to which the crystal structure belongs is identified through matching searches of the XRD pattern. In the XRD pattern, points with a height of 1 / 100 or more of the height of the highest peak are considered peaks. The integrated intensity is obtained by integrating the intensity within the region considered to be a peak. (200) " represents the integrated intensity of the 200 diffraction peak. The 200 diffraction peak (28°≦2θ≦32°) corresponds to the 200 plane. (020) This represents the integrated intensity of the O20 diffraction peak. The O20 diffraction peak (16°≦2θ≦18°) corresponds to the O20 plane.

[0034] Crystallite size is calculated using the Scherrer method. At the 020 diffraction peak, the full width at half maximum (FWHM) is determined relative to the background. FWHM is the width of the peak at half its height. The crystallite size is determined by the following formula. D = Kλ / Bcosθ D: Crystallite size (unit: nm) K: Scherrer constant (=0.89) λ: Wavelength of X-ray (unit: nm) B: FWHM (unit: rad) θ: Bragg angle (unit: rad)

[0035] "D50" indicates the particle size at which the cumulative value in the volume-based particle size distribution (cumulative distribution) reaches 50%. The volume-based particle size distribution is measured using a laser diffraction particle size analyzer.

[0036] "Maximum Ferret diameter" refers to the length of the longer side of the minimum bounding box (MBR) of a particle in a Scanning Electron Microscope (SEM) or Transmission Electron Microscope (TEM) image of the particle.

[0037] The chemical composition of the compound can be measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy). A sample solution is prepared by dissolving 0.1 g of the sample (e.g., positive electrode active material) in a mixed acid (10 ml) of hydrochloric acid and sulfuric acid. The sample solution is diluted to an appropriate concentration in a volumetric flask. After dilution, compositional analysis is performed using an ICP-AES instrument. For example, a product name such as "PS3520 UVDD II (manufactured by Hitachi High-Tech Science Corporation)" may be used.

[0038] The stoichiometric composition formula shows a representative example of a compound. The compound may have a non-stoichiometric composition. For example, "Al2O3" is not limited to compounds with a molar ratio of "Al / O = 2 / 3". Unless otherwise specified, "Al2O3" refers to a compound containing Al and O in any molar ratio. For example, the compound may be doped with trace elements. Some of the Al and O may be substituted with other elements.

[0039] A "derivative" refers to a compound in which a part of the parent compound has been modified by at least one of the following chemical reactions: introduction of a functional group, substitution of atoms, oxidation, reduction, and other chemical reactions. The modification may be at one location or multiple locations. The "substituents" 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 (F, Cl, Br, I, etc.), 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, phosphate amide groups, sulfo groups, carboxyl groups, hydroxamic acid groups, sulfino groups, hydrazino groups, imino groups, and silyl groups. These substituents may be further substituted. If there are two or more substituents, the substituents may be the same or different. Multiple substituents may be bonded to each other to form a ring.

[0040] positive electrode active material The positive electrode active material may, for example, be in the form of a powder. The D50 of the positive electrode active material 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 positive electrode active material 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.

[0041] The positive electrode active material may contain secondary particles. Secondary particles are aggregates of primary particles. Secondary particles can have any shape. For example, secondary particles may be spherical, rod-shaped, angular, etc. If the secondary particles are spherical, improvements in packing performance can be expected, for example. The sphericity of the secondary particles may be, for example, 0.85 or higher, 0.90 or higher, or 0.95 or higher. The sphericity of the secondary particles may be, for example, 1 or less, 0.95, or 0.90 or less. "Sphericity" refers to the circularity in the SEM image. Sphericity (circularity) is calculated by the following formula. Sphericity represents the arithmetic mean of 30 secondary particles. ψ = 4πS / L 2 ψ: Sphericity (Circularity) π: Pi S: Particle cross-section (area of ​​the region enclosed by the particle's outline) L: Particle circumference (length of the particle's outline)

[0042] Primary particles may have any shape. Primary particles may be spherical, rod-shaped, angular, etc. Primary particles may be nanoparticles. The maximum Ferret diameter of primary particles may be, for example, 20 to 300 nm. The maximum Ferret diameter of primary particles may be, for example, 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 Ferret diameter of 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, or 50 nm or less. The maximum Ferret diameter of primary particles represents the arithmetic mean of 30 primary particles.

[0043] Carbon may coat the surface of the primary particles. That is, a carbon layer or carbon film may be formed on the surface of the primary particles. The carbon may coat a part of the surface of the primary particles or the entire surface of the primary particles. The carbon may be derived from sugars, for example. 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 by mass fraction with respect to the secondary particle 2. The amount of carbon attached may be, for example, 5% or less, 4% or less, or 3% or less by mass fraction with respect to the secondary particle 2.

[0044] The positive electrode active material has a crystal structure that belongs to the space group Pnma. Hereafter, compounds having this crystal structure will also be referred to as "olivine-type compounds."

[0045] The XRD pattern of olivine-type compounds is "5.8 ≤ I (200) / I (020) By satisfying the relationship "I", an improvement in output characteristics can be expected. (200) / I (020) " may be, for example, 6.0 or higher, 6.5 or higher, 7.0 or higher, 7.1 or higher, 7.5 or higher, 8.0 or higher, 8.5 or higher, 9.0 or higher, 9.5 or higher, 10.5 or higher, 11.0 or higher, 11.9 or higher, 12.0 or higher, 12.5 or higher, 13.0 or higher, 13.5 or higher, 14.0 or higher, 14.5 or higher, 14.6 or higher, 15.0 or higher, 15.5 or higher, 16.0 or higher, or 16.5 or higher. Intensity ratio "I (200) / I (020) For example, "20.0 or less, 19.0 or less, 18.0 or less, 17.0 or less, 16.8 or less, 16.5 or less, 16.0 or less, 15.5 or less, 15.0 or less, 14.6 or less, 14.5 or less, 14.0 or less, 13.5 or less, 13.0 or less, 12.5 or less, 12.0 or less, 11.9 or less, 11.0 or less, 10.5 or less, 9.5 or less, 9.0 or less, 8.5 or less, 8.0 or less, 7.5 or less, 7.1 or less, 7.0 or less, 6.5 or less, or 6.0 or less.

[0046] Improved output characteristics are expected when the positive electrode active material has a crystallite size of 210 Å or more and 2434 Å or less (21 nm or more and 243.4 nm or less). The crystallite size may be, for example, 300 Å or more, 400 Å or more, 500 Å or more, 600 Å or more, 700 Å or more, 800 Å or more, 823 Å or more, 900 Å or more, 1000 Å or more, 1100 Å or more, 1200 Å or more, 1300 Å or more, 1316 Å or more, 1400 Å or more, 1474 Å or more, 1500 Å or more, 1540 Å or more, 1600 Å or more, 1700 Å or more, 1800 Å or more, 1900 Å or more, 2000 Å or more, 2100 Å or more, 2200 Å or more, 2300 Å or more, 2400 Å or more, or 2434 Å or more. The crystallite size may be, for example, 3000 Å or less, 2500 Å or less, 2434 Å or less, 2400 Å or less, 2300 Å or less, 2200 Å or less, 2100 Å or less, 2000 Å or less, 1900 Å or less, 1800 Å or less, 1700 Å or less, 1600 Å or less, 1540 Å or less, 1500 Å or less, 1474 Å or less, 1400 Å or less, 1316 Å or less, 1300 Å or less, 1200 Å or less, 1100 Å or less, 1000 Å or less, 900 Å or less, 823 Å or less, 800 Å or less, 700 Å or less, 600 Å or less, 500 Å or less, 400 Å or less, or 300 Å or less.

[0047] The positive electrode active material may include, for example, at least one selected from the group consisting of LFP, LMP, and LMFP.

[0048] The positive electrode active material is, for example, a material with the general formula "Li a Mn 1-x Fe xIt may have a composition represented by "PO4". In the general formula, the Li composition ratio "a" may be, for example, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.4 or more. In the general formula, the Li composition ratio "a" may be, for example, 2.0 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less. In the general formula, for example, the relationship "0.5 ≤ a ≤ 1.5" may be satisfied. In the general formula, the Fe composition ratio "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, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more. In the general formula, the Fe composition ratio "x" may be, for example, 1.0 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. In the general formula, for example, the relationship "0.2 ≤ x ≤ 0.5" may be satisfied.

[0049] A dopant may be added to the positive electrode active material (olivine-type compound). The dopant represents an element other than lithium (Li), manganese (Mn), iron (Fe), phosphorus (P), and oxygen (O). The doping amount (molecular fraction relative to the amount of Li) may be, for example, 0.01 to 0.1. Examples of dopants include boron (B), nitrogen (N), halogens, silicon (Si), sodium (Na), magnesium (Mg), aluminum (Al), chromium (Cr), scandium (Sc), titanium (Ti), vanadium (V), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), selenium (Se), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), indium (In), and lead (Pb). It may also contain at least one selected from the group consisting of bismuth (Bi), antimony (Sb), tin (Sn), tungsten (W), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and actinides.

[0050] The positive electrode active material may further contain other components as long as it contains an olivine-type compound. The mixing ratio (mass ratio) of the olivine-type compound to the other components may be, for example, "olivine-type compound / other components = 9 / 1 to 1 / 9", "olivine-type compound / other components = 8 / 2 to 2 / 8", "olivine-type compound / other components = 7 / 3 to 3 / 7", or "olivine-type compound / other components = 6 / 4 to 4 / 6". The positive electrode active material may be, for example, a mixture of powder of the olivine-type compound and powder of the other components. The other components may include, for example, 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 the notation [NiCoMn] etc. indicates that the sum of the composition ratios in [] is 1. As long as the sum is 1, each component within [] can take on any compositional ratio.

[0051] liquid battery In some embodiments, the battery may be an electrolyte battery. An "electrolyte battery" refers to a battery that contains an electrolyte. For example, polymer batteries, which contain an electrolyte, belong to the category of electrolyte batteries. In some embodiments, the battery has a monopolar structure. In a monopolar structure, the power generation element may be wound or stacked. In some embodiments, the battery has a bipolar structure. As an example, a battery having a bipolar structure (bipolar battery) is described.

[0052] Figure 1 is a schematic perspective view of the battery in this embodiment. Figure 2 is a schematic cross-sectional view along the line II-II in Figure 1. Hereinafter, "orthoplane direction" refers to the direction normal to the surface of a sheet-like member (e.g., foil, electrode, etc.). "In-plane direction" refers to any direction perpendicular to the orthoplane direction. In the figures of this embodiment, the Z-axis direction corresponds to the orthoplane direction. The X-axis and Y-axis directions are examples of in-plane directions.

[0053] The battery 100 includes an outer casing 90 and a power generation element 50. The outer casing 90 houses the power generation element 50. The outer casing 90 may include, for example, a first current collector plate 91, a first laminate film 92, a second laminate film 93, and a second current collector plate 94. The first laminate film 92 and the second laminate film 93 are joined to each other at their in-plane edges. At the joint between the first laminate film 92 and the second laminate film 93, a sealing material (not shown) may be interposed between the first laminate film 92 and the second laminate film 93.

[0054] The first current collector plate 91 and the second current collector plate 94 are joined to the power generation element 50 at their ends in the stacking direction (Z-axis direction). The first laminate film 92 is joined to the first current collector plate 91. The second laminate film 93 is joined to the second current collector plate 94. A sealing material (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.

[0055] The power generation 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, in the direction perpendicular to the plane, a positive electrode layer 11, a current collector foil 13, and a negative electrode layer 12 in this order. In the in-plane direction (for example, in the X-axis direction), the current collector foil 13 extends outward relative to the positive electrode layer 11 and the negative electrode layer 12. For example, the current collector foil 13 may extend outward relative to the positive electrode layer 11 and the negative electrode layer 12 over the entire circumference in the in-plane direction.

[0056] The current collector foil 13 is a conductor. The current collector foil 13 may include, for example, a metal foil, a conductive resin layer, etc. For example, the current collector foil 13 may be formed by bonding an Al foil and a Cu foil together. A carbon material may be coated on the surface of the current collector foil 13. The carbon material may include, for example, carbon black.

[0057] The power generation element 50 includes a sealing material 30. At its in-plane end, the sealing material 30 is joined to the current collector foil 13. The sealing material 30 may, for example, be heat-welded to the current collector foil 13. For example, the sealing material 30 may be arranged around the entire circumference of the in-plane periphery. The sealing material may include, for example, a resin material. The sealing material 30 seals between adjacent current collector foils 13 in the direction perpendicular to the plane. The sealing material 30 between the current collector foils 13 partitions the cells 40. A cell 40 is the smallest unit of the power generation element 50. The battery 100 includes multiple cells 40 and may also be called a "bipolar module". Each of the multiple cells 40 is sealed. The multiple cells 40 are isolated from each other. Each of the multiple cells 40 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte.

[0058] Positive electrode layer The positive electrode layer 11 is attached to one side of the current collector foil 13. For example, grooves may be formed in the positive electrode layer 11. The positive electrode layer 11 may be formed in a striped pattern, for example. The positive electrode layer 11 contains a positive electrode active material. That is, the battery 100 contains a positive electrode active material. Details of the positive electrode active material are as described above.

[0059] The positive electrode layer 11 may further contain, for example, a conductive material and a binder, in addition to the positive electrode active material. The amount of conductive material may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material. The conductive material may contain any components. For example, the conductive material may contain at least one selected from the group consisting of graphite, acetylene black (AB), Ketjenblack (registered trademark), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes (GF).

[0060] The amount of binder may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material. The binder may contain any components. 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), carboxymethylcellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyoxyethylene alkyl ethers, and derivatives thereof.

[0061] The positive electrode layer 11 may further contain, for example, inorganic fillers, organic fillers, solid electrolytes, surface modifiers, dispersants, lubricants, flame retardants, protective agents, fluxes, coupling agents, adsorbents, etc. The positive electrode layer may also contain, for example, polyoxyethylene allylphenyl ether phosphate, zeolite, silane coupling agents, MoS2, WO3, etc.

[0062] Negative electrode layer The negative electrode layer 12 is attached to one side of the current collector foil 13. The negative electrode layer 12 is located 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 contains a negative electrode active material.

[0063] The negative electrode active material may be in the form of parts or sheets, for example. 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.

[0064] The negative electrode active material may contain any components. For example, the negative electrode active material may include at least one selected from the group consisting of carbon-based active materials, alloy-based active materials, Si-C composite materials, Li metal, Li-based alloys, and lithium titanate. In some embodiments of this invention, the battery may be a Li metal negative electrode battery.

[0065] The carbon-based active material may include at least one selected from the group consisting of, for example, graphite, soft carbon, and hard carbon. "Graphite" is a general term for natural graphite and artificial graphite. 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".

[0066] 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 include at least one selected from the group consisting of, for example, P, W, Al, and O. The different material may include at least one selected from the group consisting of, for example, Al(OH)3, AlOOH, Al2O3, WO3, Li2CO3, LiHCO 3、 and, for example, at least one selected from the group consisting of Li3PO4.

[0067] The alloy-based active material may include at least one selected from the group consisting of, for example, Si, Li silicate, SiO, Si-based alloy, tin (Sn), SnO, and Sn-based alloy.

[0068] 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.

[0069] "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).

[0070] Separator The separator 20 can separate the positive electrode layer 11 from the negative electrode layer 12. The separator 20 has electrical insulating 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.

[0071] The resin film is porous. The resin film may include, for example, a microporous membrane, a nonwoven fabric, etc. The resin film includes a resin skeleton. The resin skeleton may be continuous, for example, in a mesh-like manner. Pores are formed in the gaps of the resin skeleton. The resin film can permeate the electrolyte. 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 the mercury intrusion method. The Gaurle value of the resin film is, for example, 50 to 250 s / 100 cm. 3 It may also be the case that the "Gehré value" can be measured by the Gehré test method.

[0072] The resin film may contain at least one selected from the group consisting of, for example, olefin resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, acrylic resins, and polyester resins. The resin film may also contain at least one selected from the group consisting of, for example, polyethylene (PE), polypropylene (PP), polyamide (PA), polyamide-imide (PAI), polyimide (PI), aromatic polyamide (aramid), polyphenylene ether (PPE), and derivatives thereof. The resin film can be formed, for example, by stretching, phase separation, or the like. The thickness of the resin film may be, for example, 5 to 50 μm or 10 to 25 μm.

[0073] The resin film may have, for example, a single-layer structure. The resin film may consist of, for example, a PE layer. The framework of the PE layer is formed of PE. The PE layer may have a shutdown function. The resin film may have, for example, a multilayer structure. The resin film may include, for example, a PP layer and a PE layer. The framework 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 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.

[0074] 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.

[0075] The inorganic particle layer is porous. The inorganic particle layer contains inorganic particles. The inorganic particles may also be called "inorganic fillers." 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 called an "HRL (Heat Resistance Layer)." The inorganic particles may contain at least one selected from the group consisting of boehmite, alumina, zirconia, titania, magnesia, and silica. The inorganic particles may have any shape. For example, the inorganic particles may be spherical, rod-shaped, plate-shaped, fibrous, etc. 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 include, for example, at least one selected from the group consisting of acrylic resins, polyamide resins, fluororesins, aromatic polyether resins, and liquid crystal polyester resins.

[0076] 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.

[0077] 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 called "organic fillers". The organic particles may contain heat-resistant materials. The organic particles may contain at least one selected from the group consisting of, for example, PE, PP, PTFE, PI, PAI, PA, and aramid. The organic particles may be spherical, rod-shaped, plate-shaped, fibrous, etc. The D50 of the organic particles may be, for example, 0.1 to 10 μm, or 0.5 to 3 μm.

[0078] The separator 20 may include, for example, a mixed layer. The mixed layer may contain both inorganic and organic particles.

[0079] electrolyte The electrolyte is a liquid electrolyte. The electrolyte contains a solute and a solvent. The concentration of the solute may be, for example, 0.5 to 1 mole / L, 1 to 1.5 mole / L, 1.5 to 2 mole / L, 2 to 2.5 mole / L, or 2.5 to 3 mole / L. "mol / L" may also be written as "M". The solute contains a supporting salt (Li salt). The solute may also contain, for example, inorganic acid salts, imide salts, oxalate complexes, halides, 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.

[0080] The electrolyte may contain, for example, a carbonate-based solvent (carbonate ester-based solvent). The solvent may contain, for example, cyclic carbonates, linear carbonates, fluorinated carbonates, etc. 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.

[0081] The solvent may contain cyclic carbonates (EC, PC, FEC, etc.) and linear carbonates (EMC, DMC, DEC, etc.). The mixing ratio (volume ratio) of cyclic carbonates to linear carbonates may be, for example, "cyclic carbonate / linear carbonate = 1 / 9 to 4 / 6", "cyclic carbonate / linear carbonate = 2 / 8 to 3 / 7", or "cyclic carbonate / linear carbonate = 3 / 7 to 4 / 6".

[0082] The solvent may contain cyclic carbonates (EC, PC, etc.) and fluorinated cyclic carbonates (FEC, etc.). The mixing ratio (volume ratio) of cyclic carbonates to fluorinated cyclic carbonates 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".

[0083] The solvent may include, for example, EC, FEC, EMC, DMC, and DEC. The volume ratio of each component can be expressed, for example, by the relationship "V EC +V FEC +V EMC +V DMC +V DEC The relationship expressed by "=10" may also be satisfied. In the relationship, "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" and "6 ≤ V EMC +V DMC +V DEC The relationship "≤9" is satisfied. For example, "1 ≤ V" EC ≤2" or "2 ≤ V"EC The relationship "≤3" may also be satisfied. For example, "1 ≤ V" FEC ≤2" or "2 ≤ V" FEC The relationship "≤4" may also be satisfied. For example, "3 ≤ V" EMC ≤4" or "6 ≤ V" EMC The relationship "≤8" may also be satisfied. For example, "3 ≤ V" DMC ≤4" or "6 ≤ V" DMC The relationship "≤8" may also be satisfied. For example, "3 ≤ V" DEC ≤4" or "6 ≤ V" DEC The relationship "≤8" may also be satisfied.

[0084] The solvent may have compositions such as "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", and "EC / FEC / DMC / EMC=1 / 2 / 3 / 4" in volume ratio.

[0085] The electrolyte may contain an ether-based solvent. The electrolyte may contain, for example, 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), ethylglycyle, triglycyle, tetraglycyle, and derivatives thereof.

[0086] The electrolyte may contain any additives. The amount of additive (mass fraction of the total electrolyte) may be, for example, 0.01 to 5%, 0.05 to 3%, or 0.1 to 1%. The additives may include, for example, SEI (Solid Electrolyte Interphase) formation promoters, SEI formation inhibitors, gas generators, overcharge inhibitors, flame retardants, antioxidants, electrode protectants, surfactants, etc.

[0087] Additives include, for example, vinylene carbonate (VC), vinylethylene carbonate (VEC), 1,3-propanesaltone (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.], and fluorobenzenes [e.g., monofluorobenzene (FB), 1,2-di-butylbenzene]. 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.), fluorotoluene (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-methyl benzothiazole) It may contain at least one selected from the group consisting of (e.g., nzothiazole, tetrathiafulvalene), nitrile compounds (e.g., adiponitrile, succinonitrile), phosphate esters (e.g., trimethyl phosphate, triethyl phosphate), carboxylic acid anhydrides (e.g., acetic anhydride, propionic anhydride, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride), alcohols (e.g., methanol, ethanol, n-propyl alcohol, ethylene glycol, diethylene glycol monomethyl ether), and derivatives thereof.

[0088] The components mentioned above may be used as solutes and solvents, or as trace components (additives). The additives may include, for example, at least one selected from the group consisting of LiBF4, LiFSI, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPO2F2, FSO3Li, LiI, LiBr, HFE, DOX, PC, FEC, and derivatives thereof.

[0089] The electrolyte may contain an ionic liquid. The ionic liquid may contain, 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.

[0090] In some embodiments of this 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.

[0091] all solid state battery In some embodiments of this 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 an electrolyte and a separator 20. The solid electrolyte may also be included in the positive electrode layer 11 and the negative electrode layer 12. Instead of a separator 20, the solid electrolyte layer separates the negative electrode layer 12 from the positive electrode layer 11. The solid electrolyte layer includes, for example, a solid electrolyte and a binder.

[0092] 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.

[0093] The solid electrolyte may include, for example, at least one selected from the group consisting of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, hydride solid electrolytes, and nitride solid electrolytes.

[0094] The sulfide solid electrolyte may contain at least one 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). In addition to Li and S, the sulfide solid electrolyte may further contain any other components.

[0095] 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, Li 10 GeP2S 12 Li4P2S6, Li7P3S 11 It may include at least one selected from the group consisting of Li3PS4 and Li7PS6.

[0096] For example, "LiI-LiBr-Li3PS4" indicates a sulfide solid electrolyte produced by mixing LiI, LiBr, and Li3PS4 in any molar ratio. For example, the sulfide solid electrolyte may be produced by a mechanochemical method. The mixing ratio may be specified by prefixing each raw material with a number. For example, "10LiI-15LiBr-75Li3PS4" indicates that the mixing ratio is "LiI / LiBr / Li3PS4 = 10 / 15 / 75 (molar ratio)".

[0097] A sulfide solid electrolyte may have a composition represented by the general formula "xLi2S-(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 also 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", "xLi2S-(1-x)P2S5" may have the composition of Li3PS4.

[0098] 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" could be, for example, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, or 5 or less.

[0099] Sulfide solid electrolytes are, for example, those with the general formula "Li 7-x-2y PS 6-x-y X y It may have a composition represented by the formula: 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 selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0100] Sulfide solid electrolytes are, for example, those with 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.

[0101] The sulfide solid electrolyte may have a composition represented by, for example, 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, a LGPS-type crystal phase.

[0102] The halide solid electrolyte may have a composition represented by, for example, 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.

[0103] The halide solid electrolyte may have a composition represented by, for example, the general formula "Li 3-a Tia Al 1-a It may have a composition represented by "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.

[0104] The halide solid electrolyte may have a composition represented by, for example, the general formula "Li3YCl a Br b I 6-a-b ". In the general formula, for example, the relationship of "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.

[0105] The oxide solid electrolyte may contain, for example, at least one selected from the group consisting of LiNbO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, La 2 / 3-x Li 3x TiO3, and Li7La3Zr2O 12 and may contain at least one selected from the group consisting of. The hydride solid electrolyte may contain, for example, LiBH4 or the like. The nitride solid electrolyte may contain, for example, Li3N, Li3BN2 or the like.

Examples

[0106] Preparation of Samples Figure 3 is a table showing the experimental results. The positive electrode active materials of No. 1 to No. 8 were produced by the following procedure.

[0107] Formation of Slurry Compositional formula “Li 1.04 Mn 0.6 Fe 0.4 Lithium hydroxide monohydrate, manganese carbonate, ferric phosphate, and lithium dihydrogen phosphate are weighed out to match the composition ratio shown in "PO4". 8% glucose is weighed out by mass fraction relative to the total mass of the raw materials. The glucose forms a carbon layer on the surface of the primary particles in the final product. The weighed materials are mixed with water to form a slurry. The solid content of the slurry is 30% by mass fraction. Wet grinding is performed to achieve a D50 of 0.30 μm.

[0108] Formation of secondary particles Secondary particles are formed by spray drying of the slurry. Each of the primary particles constituting the secondary particles is a precursor of LMFP. The target value for the D50 of the secondary particles is 9 ± 1 μm. The spray dryer settings are as follows: Air intake temperature: 250℃ Exhaust vent temperature: 115±15℃ Intake pressure: 2.0 MPa Spray nozzle pressure: 0.2 ± 0.1 MPa

[0109] firing Secondary particles (precursors) are placed in a graphite crucible. The graphite crucible is placed inside a heat treatment furnace. Under a nitrogen atmosphere, the material is fired to form a sintered body.

[0110] First firing method No. 1 and No. 2 are synthesized by the first firing method. First, the furnace temperature is raised to 200°C at a heating rate of 3°C / min. The furnace temperature is maintained at 200°C for 1 hour. Next, the furnace temperature is raised to 650°C at a heating rate of 5°C / min. The furnace temperature is maintained at 650°C for 5 hours. After that, the furnace is cooled to 400°C at a cooling rate of 2°C / min. The furnace is further cooled to room temperature at a cooling rate of 15°C / min.

[0111] Second firing method Nos. 3 to No. 8 are synthesized by the second firing method. First, the temperature inside the furnace is raised to 200 °C at a heating rate of 3 °C / min. The temperature inside the furnace is maintained at 200 °C for 1 hour. Then, the temperature inside the furnace is raised to 1000 °C or higher at a heating rate of 5 °C / min, causing the precursor to melt. The molten state is maintained for 5 hours at 1000 °C or higher. Thereafter, the furnace is cooled to 600 °C at a cooling rate of 10 °C / min. The temperature inside the furnace at 600 °C is maintained for 5 hours. Further, the furnace is cooled to room temperature at a cooling rate of 15 °C / min.

[0112] In the second firing method, crystallization is considered to progress due to rapid cooling from the molten state. Note that in a temperature environment of 700 °C or higher, the possibility of containing impurities increases as crystal growth progresses. Therefore, in the second firing method, it is rapidly cooled to 600 °C once. While maintaining 60's °C, crystal growth progresses. Thereby, reduction of impurities is expected.

[0113] Crushing The sintered body is crushed by a ball mill, mortar, etc. By passing the crushed material through a 75-μm sieve, the positive electrode active material (powder of LMFP) is obtained. The XRD pattern of the positive electrode active material is acquired. The intensity ratio "I (200) / I (020) " and the crystallite size "D" are measured.

[0114] Evaluation An evaluation cell containing the positive electrode active material is fabricated. The evaluation cell is a liquid-based lithium-ion secondary battery. In the evaluation cell, the IV resistance is measured. The lower the IV resistance, the better the output characteristics are considered to be. The "normalized IV resistance" in Fig. 3 is a value normalized with the IV resistance of No. 1 being 1.00.

[0115] Experimental Results As shown in Fig. 3, when the XRD pattern satisfies the relationship of "5.8 ≦ I (200) / I (020) ", there is a tendency for the output characteristics to improve.

[0116] Fig. 4 shows the intensity ratio "I (200) / I(020) This is a graph showing the relationship between " and IV resistance. In Figure 4, for example, "I (200) / I (020) ≤16.8", I (200) / I (020) When relationships such as "≤14.6" are satisfied, there is a tendency for the output characteristics to improve.

[0117] Figure 5 is a graph showing the relationship between crystallite size "D" and IV resistance. Figure 5 plots the results for No. 3 to No. 8. In Figure 5, for example, when relationships such as "210 Å ≤ D ≤ 2434 Å" and "D ≤ 1540 Å" are satisfied, there is a tendency for the output characteristics to improve. [Explanation of Symbols]

[0118] 10 Bipolar electrode, 11 Positive electrode layer, 12 Negative electrode layer, 13 Current collector foil, 20 Separator, 30 Sealing material, 40 Cell, 50 Power generation element, 90 Outer casing, 91 First current collector plate, 92 First laminate film, 93 Second laminate film, 94 Second current collector plate, 100 Battery.

Claims

1. It has a crystal structure that belongs to the space group Pnma, X-ray diffraction pattern 5.8≦I (200) / I (020) Satisfying the relationship, The above I (200) This shows the integrated intensity of the 200 diffraction peak, and, The above I (020) This shows the integrated intensity of the 020 diffraction peak. Cathode active material.

2. The aforementioned X-ray diffraction pattern I (200) / I (020) ≦16.8 Satisfying the relationship, The positive electrode active material according to claim 1.

3. The aforementioned X-ray diffraction pattern I (200) / I (020) ≦14.6 Satisfying the relationship, The positive electrode active material according to claim 2.

4. Having a crystallite size of 210 Å or more and 2434 Å or less, The positive electrode active material according to any one of claims 1 to 3.

5. Having a crystallite size of 1540 Å or less, The positive electrode active material according to claim 4.

6. It includes at least one selected from the group consisting of lithium manganese phosphate and lithium iron manganese phosphate, The positive electrode active material according to any one of claims 1 to 3.

7. It includes a positive electrode layer, and The positive electrode layer comprises the positive electrode active material described in any one of claims 1 to 3. electrode.

8. Including the electrode described in claim 7, battery.

9. Having a bipolar structure, The battery according to claim 8.

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