Positive electrode active material, electrode, and battery

Abstract

The invention relates to a positive active material, an electrode and a battery. The purpose of the present disclosure is to improve output characteristics. The positive electrode active material of the present disclosure contains primary particles. The primary particles include an olivine-type phosphate compound. In a cross section of the primary particle, a line profile based on a signal intensity of phosphorus obtained by TEM-EDS line analysis along a diameter direction of the primary particle includes a first region and a second region. The first regions are located at both ends of the primary particles. The second region is located between the first regions. The signal strength of phosphorus in the first region is lower than that in the second region. The width of the first region is 0.5 to 20 nm.

Description

Technical Field

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

[0002] International Publication No. 2016 / 158566 discloses lithium manganese phosphate nanoparticles characterized by crystal orientation. Summary of the Invention

[0003] As positive electrode active materials, olivine-type phosphate compounds such as lithium manganese phosphate are being studied. Olivine-type phosphate compounds tend to have low specific capacity. In the past, studies have been conducted to improve specific capacity, for example, by controlling crystal orientation. However, there is still room for improvement in output characteristics.

[0004] The purpose of this disclosure is to improve output characteristics.

[0005] The following describes the technical solution and effects of this disclosure. However, the mechanism of action of this disclosure includes presumptions. The mechanism of action does not limit the technical scope of this disclosure.

[0006] 1. One aspect of this disclosure is a positive electrode active material. The positive electrode active material comprises primary particles. The primary particles comprise olivine-type phosphate compounds. In the cross-section of the primary particles, the line profile of the phosphorus signal intensity obtained based on TEM-EDS line analysis along the diameter direction of the primary particles includes a first region and a second region. The first region is located at both ends of the primary particles. The second region is located between the first regions. The phosphorus signal intensity in the first region is lower than that in the second region. The width of the first region is 0.5~20 nm.

[0007] Region 1 is considered to correspond to the "outermost surface" of primary particles. Region 2 is considered to correspond to the "body" of primary particles. In TEM-EDS (Transmission Electron Microscope Energy Dispersive X-ray Spectroscopy) line analysis, the signal intensity of phosphorus (P) corresponds to the P concentration at the measurement location. Within the P concentration profile, a region of low P concentration exists at the outermost surface of primary particles, and when the width of this region is 5–20 nm, improved output characteristics can be expected.

[0008] 2. The positive electrode active material described in "1" above may also include, for example, the following: The positive electrode active material includes secondary particles. The secondary particles include multiple primary particles. In the cross-section of the secondary particles, the line profile of the phosphorus signal intensity obtained based on TEM-EDS line analysis along the diameter direction of the secondary particles repeatedly rises and falls.

[0009] In secondary particles, primary particles are arranged in a manner that repeatedly rises and falls along a line profile with a signal intensity of P, thereby expecting to improve output characteristics. In secondary particles, the valleys in the line profile are considered to correspond to the first region of the primary particles. The width of the first region is considered to be related to the degree of necking between primary particles. When necking occurs, the width of the first region (low-concentration region) decreases. If necking is excessive, the output characteristics may decrease due to the increased conduction distance between ions and electrons. On the other hand, if the width of the first region (low-concentration region) is too large, the conduction network between particles becomes coarser, which may also reduce output characteristics. It is believed that a width of 5–20 nm in the first region (low-concentration region) of the line profile allows for the formation of a suitable conduction distance and network.

[0010] 3. The positive electrode active material described in "2" above may also include, for example, the following scheme. In the online profile, the average spacing between the valleys of phosphorus signal intensity is 11~290 nm.

[0011] When the average spacing between valleys (the average spacing from valley to valley) is 11~290nm, the output characteristics can be expected to be further improved.

[0012] 4. The positive electrode active material described in "2" or "3" above may also include, for example, the following: In the online profile, the ratio of the minimum signal intensity of phosphorus to the maximum signal intensity of phosphorus is 0.90 or less.

[0013] The ratio of the minimum signal intensity to the maximum signal intensity of phosphorus can be called the "peak-to-valley ratio". When the peak-to-valley ratio is below 0.90, further improvement in output characteristics can be expected.

[0014] 5. The positive electrode active material described in "4" above may also include, for example, a scheme. The ratio of the minimum value to the maximum value is 0.69 or less.

[0015] When the peak-to-valley ratio is below 0.69, further improvements in output characteristics can be expected.

[0016] 6. The positive electrode active material described in "5" above may also include, for example, a scheme. The ratio of the minimum value to the maximum value is 0.48 or less.

[0017] When the peak-to-valley ratio is below 0.48, further improvements in output characteristics can be expected.

[0018] 7. The positive electrode active material described in any of "1" to "6" above may also include the following: The olivine-type phosphate compound includes at least one selected from lithium iron phosphate (LFP), lithium manganese phosphate (LMP), and lithium manganese iron phosphate (LMFP).

[0019] 8. One aspect of this 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 "1" to "7" above.

[0020] The positive electrode layer can also be called the "positive electrode active material layer" or the "positive electrode compound layer". As long as an "electrode" contains a positive electrode layer, it can be either a "monopolar electrode (positive electrode)" or a "bipolar electrode".

[0021] 9. One aspect of this disclosure is a battery. The battery includes the electrodes described in "8" above.

[0022] 10. The battery described in "9" above may also include the following configuration: The battery has a bipolar structure.

[0023] Bipolar structures can be formed by stacking bipolar electrodes. Improvements in output characteristics can be expected, for example, through the use of bipolar structures.

[0024] The following describes one embodiment (hereinafter referred to as "this embodiment") and one example of this disclosure (hereinafter referred to as "this example"). However, this embodiment and this example do not limit the technical scope of this disclosure. This embodiment and this example are illustrative in all respects. This embodiment and this example are non-limiting. The technical scope of this disclosure includes all modifications within the meaning and scope equivalent to the claims. For example, it is intended from the outset to include any solutions extracted from this embodiment and to combine them arbitrarily.

[0025] The above and other objects, features, aspects and advantages of this disclosure will become more apparent from the following detailed description of this disclosure, which will be understood in conjunction with the accompanying drawings. Attached Figure Description

[0026] Figure 1 This is a conceptual diagram of TEM-EDS line analysis of a primary particle.

[0027] Figure 2 This is a conceptual diagram of TEM-EDS line analysis of secondary particles.

[0028] Figure 3 This is a conceptual diagram of the positive electrode active material in this embodiment.

[0029] Figure 4 This is a schematic flowchart illustrating the method for manufacturing the positive electrode active material according to this embodiment.

[0030] Figure 5 This is a schematic perspective view of the battery according to this embodiment.

[0031] Figure 6 It is along Figure 5 A rough cross-sectional view of line VI-VI in the diagram.

[0032] Figure 7 It is the temperature curve during firing.

[0033] Figure 8 This is a table representing the experimental results. Detailed Implementation

[0034] -Terms and phrases-

[0035] "Possessing," "Including," "Having," and their variations are open-ended expressions. Structures expressed in an open-ended manner may include additional elements besides the necessary ones, or they may not include additional elements. The statement "Composed of..." is a closed-ended expression. However, even structures expressed in a closed-ended manner may include usually accompanying impurities and additional elements unrelated to the target technology. The statement "Substantially composed of..." is a semi-closed-ended expression. In structures expressed in a semi-closed manner, it is permissible to add elements that do not substantially affect the basic and new characteristics of the target technology.

[0036] The expressions "maybe" and "can" are not used in an obligatory sense (meaning "must do this"), but rather in a permissive sense (meaning "this possibility exists").

[0037] Unless otherwise specified, the order in which the various steps, actions, and operations involved in a method are executed is not limited to the order in which they are recorded. For example, multiple steps can be performed simultaneously. Or, multiple steps can be performed sequentially.

[0038] The use of terms like "first," "second," etc., is solely for distinguishing multiple elements from one another. This use makes no distinction regarding the elements to which they are attached. For example, it is unrelated to the order or importance of the elements to which they are attached.

[0039] Geometric terms should not be interpreted strictly. Examples of geometric terms include "parallel," "perpendicular," and "orthogonal." For instance, directions, angles, and distances can also be relative displacements within a range where substantially the same or similar functions can be achieved. Geometric terms can also encompass tolerances and errors in design, operation, and manufacturing. Dimensional relationships in drawings sometimes differ from actual dimensional relationships. To aid understanding, dimensional relationships in drawings are sometimes altered. For example, length, width, and thickness may be changed. Sometimes, parts of the structure may be omitted.

[0040] Unless otherwise specified, elements described in the "singular form" can also include plural forms. For example, "particle" can sometimes refer to multiple particles, a collection of particles, or a powdery mass. Furthermore, "multiple particles" can also be referred to as a "particle swarm."

[0041] Unless otherwise specified, the numerical range "m~n%" includes both an upper and lower limit. That is, "m~n%" represents a numerical range of "m% and below n%". Furthermore, "m% and below n%" includes "more than m% and less than n%". "Above" and "below" are represented by inequality signs "≤" and "≥" with an equal sign. "More than" and "less than" are represented by inequality signs "<" and ">" without an equal sign. New upper or lower limits can also be set by arbitrarily selecting values ​​from the numerical range. For example, new numerical ranges can be set by arbitrarily combining values ​​from the numerical range with values ​​described in other parts of this specification, tables, and figures.

[0042] All numerical values ​​are modified by the term "approximately". The term "approximately" can mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​can be approximate values ​​that may vary depending on the application of the technology. All numerical values ​​can be expressed with significant figures. Unless otherwise specified, the measured value can be the average of multiple measurements. The number of measurements can be 3 or more, 5 or more, or 10 or more. Generally, the more measurements are expected, the higher the reliability of the average value. The measured value can be rounded based on the number of significant figures. The measured value may include, for example, errors such as the detection limits of the accompanying measuring device.

[0043] The apparatus and software used in the determination of various values ​​are just one example. Products equivalent to the illustrated apparatus can also be used. When using equivalent products, the measurement conditions can be adjusted in conjunction with the apparatus.

[0044] TEM-EDS line analysis of primary and secondary particles is performed in the following order: Samples are prepared by embedding the positive electrode active material (powder) in resin. The sample is then sliced ​​using a FIB (Focused Ion Beam) or CP (CrossSection Polisher). The sample is observed using TEM. For ease of measurement, secondary particles of a certain size can be screened out. For example, EDS line analysis of primary and secondary particles can be performed on secondary particles with a maximum Feretta diameter of 10 μm or more.

[0045] The magnification can be, for example, around 10,000 to 50,000 times. For example, in the case of secondary particles around 10 μm in size, the magnification can be around 10,000 times. In this case, for example, it is possible to obtain a TEM image covering the area from the center to the outermost periphery of the secondary particle. For example, the magnification for primary particles can be around 20,000 times.

[0046] Figure 1This is a conceptual diagram of TEM-EDS line analysis for a primary particle. In a cross-sectional TEM image, the contour of the primary particle 1 is fitted with a minimum circumcircle. The diameter direction of the minimum circumcircle is considered the diameter direction of the primary particle. By performing TEM-EDS line analysis along the diameter direction of the primary particle, the line profile of the signal intensity of P is obtained. TEM-EDS line analysis is performed across the primary particle in the diameter direction. At both ends of the primary particle, relatively low signal intensities can be observed within a certain range. For example, the range where up to 105% of the signal intensity is observed relative to the minimum signal intensity is considered as region 1a. Between region 1a and region 1a, relatively high signal intensities can be observed within a certain range. For example, the range where up to 95% of the signal intensity is observed relative to the maximum signal intensity is considered as region 2b. The arithmetic mean of the width "X1" of region 1a at one end and the width "X2" of region 1a at the other end is considered as the width "X" of region 1a.

[0047] Figure 2 This is a conceptual diagram of TEM-EDS line analysis for secondary particles. In a cross-sectional TEM image, the contour of secondary particle 2 is fitted with a minimum circumcircle. The diameter direction of the minimum circumcircle is considered the diameter direction of the secondary particle. By performing TEM-EDS analysis along the diameter direction of the secondary particle, a line profile of the signal intensity of P is obtained. For example, TEM-EDS analysis can also be performed within a range greater than 1 / 4 (or 1 / 2) of the diameter of the minimum circumcircle. For example, TEM-EDS analysis can also be performed from near the center of secondary particle 2 to the outermost periphery of the secondary particle. For example, TEM-EDS analysis can be performed across secondary particle 2. The line profile may sometimes rise and fall. In adjacent valley clusters of 5 or more, the arithmetic mean of the valley intervals is considered the average interval "Y".

[0048] Calculate the minimum signal strength "Z" among five or more adjacent valley groups. 2 min "Calculate the maximum signal strength among five or more adjacent peak groups." 2 max The peak-to-valley ratio "Z" is calculated by dividing the minimum value by the maximum value.

[0049] "Maximum Feret diameter" refers to the length of the longest side of the smallest bounding rectangle (rectangle or square) of the particle. When the smallest bounding rectangle is a square, the length of the longest side represents the length of the side.

[0050] "D50" indicates the particle size at which the cumulative value in the volumetric particle size distribution (cumulative distribution) reaches 50%. The volumetric particle size distribution is determined using a laser diffraction particle size distribution measuring device.

[0051] The chemical composition of a compound can be determined using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy). A sample solution is prepared by dissolving 0.1 g of the sample (e.g., a positive electrode active material) in a mixed acid solution (10 ml) of hydrochloric acid and sulfuric acid. The sample solution is then diluted to an appropriate concentration using a volumetric flask. After dilution, compositional analysis is performed using an ICP-AES apparatus. For example, product names such as "PS3520UVDD II (manufactured by Hitachi High Technology Co., Ltd.)" can also be used.

[0052] A stoichiometric formula represents a representative example of a compound. Compounds can also have non-stoichiometric compositions. For example, "Al₂O₃" is not limited to compounds having 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, trace elements can be doped into the compound. A portion of Al and O can also be replaced by other elements.

[0053] "Derivative" refers to a compound that has been altered in part by at least one of the following chemical reactions: introduction of a functional group, substitution of an atom, oxidation, reduction, and others. The alteration may occur at one or more sites. "Substituents" may include, for example, at least one of the following: alkyl, alkenyl, alkynyl, cycloalkyl, unsaturated cycloalkyl, aryl, heterocyclic, halogen (F, Cl, Br, I, etc.), OH, SH, CN, SCN, OCN, nitro, alkoxy, unsaturated alkoxy, amino, alkylamino, dialkylamino, aryloxy, acyl, alkoxycarbonyl, acyloxy, aryloxycarbonyl, acylamino, alkoxycarbonyl, aminoaryloxycarbonylamino, sulfonylamino, aminosulfonyl, carbamoyl, alkylthio, arylthio, sulfonyl, sulfinyl group, urea, phosphoramide, sulfonyl, carboxyl, oxime, sulfino group, hydrazine, imino, and silyl. These substituents can be further substituted. When there are two or more substituents, the substituents can be the same or different. Multiple substituents can combine to form a ring.

[0054] -Positive active material-

[0055] Figure 3This is a conceptual diagram of the positive electrode active material according to this embodiment. The positive electrode active material includes primary particles 1. "Primary particle" refers to the smallest unit of a particle. The maximum Feret diameter of the primary particle 1 can be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 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, 250 nm or more, 300 nm or more, 350 nm or more, 400 nm or more, or 450 nm or more. The maximum Feret diameter of the primary particle 1 can be, for example, less than 1 μm, less than 500 nm, less than 450 nm, less than 400 nm, less than 350 nm, less than 300 nm, less than 250 nm, less than 200 nm, less than 150 nm, less than 100 nm, less than 75 nm, less than 50 nm, less than 25 nm, less than 20 nm, less than 15 nm, less than 10 nm, or less than 5 nm. The maximum Feret diameter of a primary particle 1 represents the arithmetic mean of 30 primary particles 1. A primary particle 1 can have any shape. For example, a primary particle 1 can be spherical, rod-shaped, angular, etc.

[0056] Primary particle 1 contains a phosphate (PO4) framework. At the outermost surface of primary particle 1, the P concentration locally decreases. Specifically, the line profile of the P signal intensity obtained from TEM-EDS line analysis along the diameter direction of the primary particle includes region 1a and region 1b. The P signal intensity is lower in region 1a compared to region 1b. The minimum signal intensity within region 1a is [value missing]. 1 min "The maximum signal strength relative to region 1b" Z 1 max "ratio" Z 1 min / Z 1 max "Less than 1. Compared to"Z 1 min / Z 1 max "For example, it can be below 0.90, below 0.80, below 0.70, below 0.60, below 0.50, below 0.40, below 0.30, below 0.20, or below 0.10. The ratio of "Z1 / Z2" can be greater than 0, above 0.10, above 0.20, above 0.30, above 0.40, above 0.50, above 0.60, above 0.70, or above 0.80."

[0057] Region 1a is located at both ends of primary particle 1. Region 1b is located between regions 1a. Therefore, it is considered that in the cross-section of primary particle 1, region 1b is surrounded by region 1a.

[0058] The width "X" of region 1a is 0.5~20nm. For example, the width "X" can be 1nm or more, 2.5nm or more, 5nm or more, 7.5nm or more, 10nm or more, 12.5nm or more, 15nm or more, or 17.5nm or more. For example, the width "X" can be less than 17.5nm, less than 15nm, less than 12.5nm, less than 10nm, less than 7.5nm, less than 5nm, less than 2.5nm, or less than 1nm.

[0059] The width of region 1b can, for example, be larger than the width "X" of region 1a. The width of region 1b can be, for example, 1nm or more, 5nm or more, 10nm or more, 15nm or more, 20nm or more, 25nm or more, 50nm or more, 75nm or more, 100nm or more, 150nm or more, 200nm or more, 250nm or more, 300nm or more, 350nm or more, 400nm or more, or 450nm or more. The width of region 1b can, for example, be less than 500nm, less than 450nm, less than 400nm, less than 350nm, less than 300nm, less than 250nm, less than 200nm, less than 150nm, less than 100nm, less than 75nm, less than 50nm, less than 25nm, less than 20nm, less than 15nm, less than 10nm, or less than 5nm.

[0060] Primary particle 1 can also exist alone. A single primary particle 1 is also called a "single particle". Primary particle 1 can also form secondary particle 2. That is, the positive electrode active material can also contain secondary particle 2. Secondary particle 2 is an aggregate of primary particle 1. Secondary particle 2 contains multiple primary particles 1. The number of primary particles 1 contained in one secondary particle 2 can be, for example, 2 or more, 5 or more, 10 or more, 50 or more, 100 or more, 500 or more, or 1000 or more. The number of primary particles 1 contained in one secondary particle 2 can be, for example, less than 5000, less than 1000, less than 500, less than 100, less than 50, less than 10, or less than 5.

[0061] The positive electrode active material may also contain an aggregate (powder) of secondary particles 2. The D50 of the powder may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more. The D50 may be, for example, less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 10 μm.

[0062] Secondary particles 2 can have any shape. For example, secondary particles 2 can be spherical, rod-shaped, angular, etc. By making secondary particles 2 spherical, for example, improved filling properties can be expected. The sphericity of secondary particles 2 can be, for example, 0.85 or higher, 0.90 or higher, or 0.95 or higher. Alternatively, the sphericity of secondary particles 2 can be, for example, less than 1, less than 0.95, or less than 0.90. "Sphericity" refers to the roundness in a TEM image (two-dimensional image). Sphericity (roundness) is calculated using the following formula.

[0063] ψ = 4πS / L 2

[0064] ψ: Sphericity (roundness)

[0065] π: Pi

[0066] S: Cross-sectional area of ​​secondary particle 2 (the area of ​​the region enclosed by the outline of secondary particle 2)

[0067] L: The perimeter of secondary particle 2 (the length of the outline of secondary particle 2).

[0068] Sphericity is represented by the arithmetic mean of 30 secondary particles.

[0069] In the cross-section of secondary particle 2, the line profile of the signal intensity of P obtained based on TEM-EDS line analysis along the diameter direction of the secondary particle can also be repeatedly raised and lowered. The number of repetitions can be, for example, 2 or more, 5 or more, 10 or more, 20 or more, 50 or more, 100 or more, or 200 or more. The number of repetitions can be, for example, less than 500, less than 200, less than 100, less than 50, less than 20, less than 10, or less than 5.

[0070] The rise and fall of the line profile can be periodic or non-periodic. The average interval "Y" between valleys can be, for example, 5nm or more, 10nm or more, 15nm or more, 20nm or more, 25nm or more, 50nm or more, 75nm or more, 100nm or more, 125nm or more, 150nm or more, 175nm or more, 200nm or more, 225nm or more, 250nm or more, 275nm or more, 300nm or more, 325nm or more, 350nm or more, or 400nm or more. The average interval "Y" between valleys can be, for example, below 500nm, below 450nm, below 400nm, below 350nm, below 325nm, below 300nm, below 275nm, below 250nm, below 225nm, below 200nm, below 175nm, below 150nm, below 125nm, below 100nm, below 75nm, below 50nm, below 25nm, below 20nm, or below 15nm. The average interval "Y" between valleys can be, for example, 11~290nm.

[0071] The peak-to-valley ratio "Z" of the line profile can be, for example, below 0.93, below 0.90, below 0.69, below 0.48, below 0.40, below 0.30, below 0.22, or below 0.10. The peak-to-valley ratio "Z" can be greater than 0, above 0.10, above 0.20, above 0.30, above 0.40, above 0.50, above 0.60, above 0.70, or above 0.80.

[0072] Primary particle 1 contains an olivine-type phosphate compound. "Olivine-type" indicates a crystal structure belonging to space group Pnma. The space group is identified by powder X-ray diffraction (XRD). Primary particle 1 can also be a single-phase compound, for example. As long as primary particle 1 contains an olivine-type crystalline phase, it can also contain phases belonging to other space groups. Primary particle 1 can also further contain amorphous phases, for example.

[0073] Olivine-type phosphate compounds may, for example, contain at least one selected from LFP, LMP, and LMFP. Olivine-type phosphate compounds may, for example, have a composition represented by the following general formula.

[0074] Li a Mn 1-x Fe x PO4

[0075] For example, the relationship "0.5 ≤ a ≤ 1.5" can be satisfied. "x" can be greater than or equal to 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. "x" can also be less than or equal to 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1.

[0076] Elements other than lithium (Li), manganese (Mn), iron (Fe), phosphorus (P), and oxygen (O) can also be doped into olivine-type phosphate compounds (dopants). The doping amount (mass fraction relative to the amount of Li) can be, for example, 0.01 to 0.1. The dopant may include at least one element selected from 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), lead (Pb), 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.

[0077] The positive electrode active material, as long as it contains olivine-type phosphate compounds, may also contain other components. These other components may include, for example, lithium nickel oxide (LNO), lithium cobalt oxide (LCO), and lithium manganese oxide (LMO). The mixing ratio (mass ratio) of the olivine-type phosphate compound and other components can be, for example, "olivine-type phosphate compound / other components = 9 / 1 to 1 / 9", "olivine-type phosphate compound / other components = 8 / 2 to 2 / 8", "olivine-type phosphate compound / other components = 7 / 3 to 3 / 7", or "olivine-type phosphate compound / other components = 6 / 4 to 4 / 6". The positive electrode active material can, for example, be a mixture of olivine-type phosphate compound powder and powders of other components.

[0078] LNO can have, for example, a crystal structure belonging to space group R-3m. LNO can have, for example, a composition represented by the following general formula.

[0079] Li 1-a Ni x M 1-x O2

[0080] In the formula, the relationships of -0.5 ≤ a ≤ 0.5 and 0 ≤ x ≤ 1 are satisfied. M can include, for example, at least one selected from Co, Mn, and Al. For example, the relationships of 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x ≤ 1 can be satisfied. For example, the relationships of -0.4 ≤ a ≤ 0.4, -0.3 ≤ a ≤ 0.3, -0.2 ≤ a ≤ 0.2, or -0.1 ≤ a ≤ 0.1 can be satisfied.

[0081] LNO can include, for example, at least one selected from LiNi 0.9 Co 0.1 O2, LiNi 0.9 Mn 0.1 O2, and LiNiO2.

[0082] LNO can be represented by the following general formula, for example. The compound represented by the following general formula can also be referred to as "NCM".

[0083] Li 1-a Ni x Co y Mn z O2

[0084] [[ID=·28]]In the formula, the relationships of -0.5 ≤ a ≤ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied. For example, the relationships of 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x < 1 can be satisfied. For example, the relationships of 0 < y ≤ 0.1, 0.1 ≤ y ≤ 0.2, 0.2 ≤ y ≤ 0.3, 0.3 ≤ y ≤ 0.4, 0.4 ≤ y ≤ 0.5, 0.5 ≤ y ≤ 0.6, 0.6 ≤ y ≤ 0.7, 0.7 ≤ y ≤ 0.8, 0.8 ≤ y ≤ 0.9, or 0.9 ≤ y < 1 can be satisfied. For example, the relationships of 0 < z ≤ 0.1, 0.1 ≤ z ≤ 0.2, 0.2 ≤ z ≤ 0.3, 0.3 ≤ z ≤ 0.4, 0.4 ≤ z ≤ 0.5, 0.5 ≤ z ≤ 0.6, 0.6 ≤ z ≤ 0.7, 0.7 ≤ z ≤ 0.8, 0.8 ≤ z ≤ 0.9, or 0.9 ≤ z < 1 can be satisfied.

[0085] NCM can include, for example, at least one selected from LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.3 Mn0.3 O2, LiNi 0.3 Co 0.4 Mn 0.3 O2, LiNi 0.3 Co 0.3 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.4 Mn 0.1 O2, LiNi 0.5 Co 0.1 Mn 0.4 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.3 Mn 0.1 O2, LiNi 0.6 Co 0.1 Mn 0.3 O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 and LiNi 0.9 Co 0.05 Mn 0.05 At least one of O2.

[0086] LNO can be represented by the following general formula. Compounds represented by the following general formula can also be called "NCA".

[0087] Li 1-a Ni x Co y Al z O2

[0088] In the formula, the relationships of -0.5 ≤ a ≤ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied. For example, the relationships of 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x < 1 can be satisfied. For example, the relationships of 0 < y ≤ 0.1, 0.1 ≤ y ≤ 0.2, 0.2 ≤ y ≤ 0.3, 0.3 ≤ y ≤ 0.4, 0.4 ≤ y ≤ 0.5, 0.5 ≤ y ≤ 0.6, 0.6 ≤ y ≤ 0.7, 0.7 ≤ y ≤ 0.8, 0.8 ≤ y ≤ 0.9, or 0.9 ≤ y < 1 can be satisfied. For example, the relationships of 0 < z ≤ 0.1, 0.1 ≤ z ≤ 0.2, 0.2 ≤ z ≤ 0.3, 0.3 ≤ z ≤ 0.4, 0.4 ≤ z ≤ 0.5, 0.5 ≤ z ≤ 0.6, 0.6 ≤ z ≤ 0.7, 0.7 ≤ z ≤ 0.8, 0.8 ≤ z ≤ 0.9, or 0.9 ≤ z < 1 can be satisfied.

[0089] NCA may, for example, contain a selected from LiNi 0.7 Co 0.1 Al 0.2 O2, LiNi 0.7 Co 0.2 Al 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.8 Co 0.17 Al 0.03 O2, LiNi 0.8 Co 0.15 Al 0.05 O2 and LiNi 0.9 Co 0.05 Al 0.05 at least one of O2.

[0090] Carbon may be attached to at least a part of the surface of the primary particle 1. Carbon may also form the carbon layer 3. The amount of carbon attached, for example, relative to the primary particle 1 (olivine-type phosphate compound), may be 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, or 4% or more in terms of mass fraction. The amount of carbon attached, for example, relative to the primary particle 1, may be 5% or less, 4% or less, or 3% or less in terms of mass fraction.

[0091] - Method for manufacturing a positive electrode active material -

[0092] Figure 4This is a schematic flowchart illustrating the method for manufacturing the positive electrode active material according to this embodiment. Hereinafter, "the method for manufacturing the positive electrode active material according to this embodiment" may be simply referred to as "this method". This method may include, for example, "(a) slurry formation", "(b) granulation" and "(c) calcination".

[0093] (a) Formation of slurry

[0094] This method may, for example, include a step of forming a slurry by mixing a lithium compound, a manganese compound, an iron compound, a phosphate compound, a carbon source, and a solvent. For example, it may be formulated as "Li a Mn 1-x Fe x Weigh the lithium compound, manganese compound, iron compound, and phosphate compound according to the composition ratio (mass ratio) shown in "PO4 (0.5≤a≤1.5, 0≤x<1)". The lithium compound may include, for example, lithium hydroxide. The manganese compound may include, for example, manganese carbonate. The phosphate compound may include, for example, lithium dihydrogen phosphate. The iron compound may include, for example, iron phosphate.

[0095] A carbon source is a raw material containing carbon that adheres to the surface of primary particles. Carbon sources can include, for example, sugars and organic acids. Examples of carbon sources include glucose, sucrose, fructose, and citric acid. The amount of carbon source added relative to the raw material mixture, in terms of mass fraction, can be, for example, 1 to 20%.

[0096] Solvents may include, for example, water. The concentration of solids in the slurry, expressed as a mass fraction, may be, for example, 20-40%.

[0097] By performing wet milling, the particle size in the slurry can be adjusted. For example, wet milling can be performed to make the D50 0.10~1μm. For example, the average spacing "Y" between the valleys can be adjusted according to the degree of wet milling.

[0098] (b) Granulation

[0099] This method may include, for example, a step of granulating the secondary particles (precursor) by drying the slurry. For instance, the secondary particles can also be granulated using spray drying. The secondary particles formed through the granulation operation are also referred to as "granules." That is, the secondary particles can also be called granules.

[0100] (c) Firing

[0101] This method may include a step of generating olivine-type phosphate compounds by heat-treating secondary particles (precursors). Any heat treatment furnace (e.g., electric furnace, muffle furnace, etc.) can be used. In this method, firing is carried out under conditions where necking between primary particles is unlikely to occur. The heat treatment atmosphere may be, for example, an inert atmosphere. An inert atmosphere may be, for example, a nitrogen atmosphere. The heat treatment temperature may be, for example, 400–700 °C. The heat treatment time may be, for example, 4–6 hours. For example, the width "X" of the first zone can be adjusted according to the firing conditions. For example, during the heating process during firing, the temperature is not continuously increased, but rather temporarily stopped around 200 °C and maintained at 200 °C for about 1 hour, thereby suppressing the tendency for necking to occur.

[0102] -Liquid-based batteries-

[0103] In some embodiments, the battery may be a liquid-system battery. "Liquid-system battery" refers to a battery containing an electrolyte. For example, a polymer battery contains an electrolyte and therefore belongs to the liquid-system battery category. In some embodiments, the battery has a unipolar structure. In some embodiments, the battery has a bipolar structure. As an example, a battery with a bipolar structure (bipolar battery) will be described.

[0104] Figure 5 This is a schematic perspective view of the battery according to this embodiment. Figure 6 It is along Figure 5 A schematic cross-sectional view of line VI-VI in the diagram. Hereinafter, "plane-perpendicular direction" refers to the normal direction relative to the surface of the sheet-like member (e.g., foil, electrode, etc.). "In-plane direction" refers to any direction orthogonal to the plane-perpendicular direction. In the figures of this embodiment, the Z-axis direction corresponds to the plane-perpendicular direction. The X-axis and Y-axis directions are examples of in-plane directions.

[0105] 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 also include, for example, a first current collector 91, a first laminate 92, a second laminate 93, and a second current collector 94. The ends of the first laminate 92 and the second laminate 93 are joined together in the in-plane direction. A sealing material (not shown) can be inserted between the first laminate 92 and the second laminate 93 at the joint.

[0106] The first collector plate 91 and the second collector plate 94 are joined to the power generation element 50 at their ends in the lamination direction (Z-axis direction). A first laminate 92 is joined to the first collector plate 91. A second laminate 93 is joined to the second collector plate 94. A sealing material (not shown) may also be inserted between the collector plate and the laminate at the joint.

[0107] The power generation element 50 includes a plurality of bipolar electrodes 10. The plurality of bipolar electrodes 10 are stacked in a plane-perpendicular direction (Z-axis direction). Each of the plurality of bipolar electrodes 10 sequentially includes a positive electrode layer 11, a current collector foil 13, and a negative electrode layer 12 in the plane-perpendicular direction. In the in-plane direction (e.g., the X-axis direction), the current collector foil 13 extends outward compared to the positive electrode layer 11 and the negative electrode layer 12. For example, the current collector foil 13 may extend outward along a full circumference in the in-plane direction compared to the positive electrode layer 11 and the negative electrode layer 12.

[0108] 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 can also be formed by laminating an Al foil and a Cu foil. A carbon material may also be coated on the surface of the current collector foil 13. The carbon material may include, for example, carbon black.

[0109] The power generation element 50 includes a sealing material 30. At its in-plane end, the sealing material 30 is bonded to the current collector foil 13. The sealing material 30 may also be heat-fused onto the current collector foil 13, for example. Alternatively, the sealing material 30 may be disposed along the entire periphery in the in-plane direction. The sealing material may also include, for example, a resin material. The sealing material 30 seals adjacent current collector foils 13 in the perpendicular direction between the planes. Sealing the current collector foils 13 with the sealing material 30 divides the space into units 40. Unit 40 is the smallest unit of the power generation element 50. The battery 100 includes multiple units 40 and can therefore be referred to as a "bipolar module." The multiple units 40 are individually sealed. The multiple units 40 are isolated from each other. Each of the multiple units 40 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte.

[0110] Positive electrode layer

[0111] A positive electrode layer 11 is attached to one side of the current collector foil 13. For example, a groove may be formed in the positive electrode layer 11. The positive electrode layer 11 may be formed in a strip shape, 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.

[0112] In addition to the positive electrode active material, the positive electrode layer 11 may also include, for example, conductive materials and binders. The amount of conductive material relative to 100 parts by mass of the positive electrode active material may be, for example, 0.1 to 10 parts by mass. The conductive material may contain optional components. The conductive material may contain at least one selected from, for example, graphite, acetylene black (AB), Ketjen black (registered trademark), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene sheets (GF).

[0113] The amount of binder relative to 100 parts by weight of the positive electrode active material can be, for example, 0.1 to 10 parts by weight. The binder may contain optional components. The binder may contain at least one selected from, for example, polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyoxyethylene alkyl ethers, and their derivatives.

[0114] The positive electrode layer 11 may also 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 active material layer may contain, for example, polyoxyethylene allyl phenyl ether phosphate, zeolite, silane coupling agents, MoS2, WO3, etc.

[0115] negative electrode layer

[0116] The negative electrode layer 12 is attached to one side 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 contains a negative electrode active material.

[0117] The negative electrode active material can be in particulate or sheet form. The D50 of the negative electrode active material can be, for example, 1 μm or more, 5 μm or more, or 10 μm or more. Alternatively, the D50 of the negative electrode active material can be, for example, less than 30 μm, less than 20 μm, less than 15 μm, or less than 10 μm.

[0118] The negative electrode active material may contain optional components. The negative electrode active material may contain at least one selected from, for example, carbon-based active materials, alloy-based active materials, Si-C composite materials, Li metal, Li-based alloys, and lithium titanate. In some embodiments, the battery may be a Li metal negative electrode battery.

[0119] Carbon-based active materials may include at least one selected from graphite, soft carbon, and hard carbon. "Graphite" is a general term for natural graphite and artificial graphite. Graphite may also 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".

[0120] The surface of graphite can be covered, for example, with amorphous carbon. The surface of graphite can also be covered with a dissimilar material. The dissimilar material can include, for example, at least one selected from P, W, Al, and O. The dissimilar material can include, for example, at least one selected from Al(OH)3, AlOOH, Al2O3, WO3, Li2CO3, LiHCO3, and Li3PO4.

[0121] The alloy-based active material may contain at least one selected from, for example, Si, Li silicates, SiO, Si-based alloys, tin (Sn), SnO, and Sn-based alloys.

[0122] SiO can be represented by, for example, the following general formula.

[0123] SiO x

[0124] In the formula, the relationship 0 < x < 2 must be satisfied. For example, the relationship 0.5 ≤ x ≤ 1.5 or 0.8 ≤ x ≤ 1.2 can also be satisfied.

[0125] "Si-C composite material" refers to a composite material of carbon-based active materials (such as graphite) and alloy-based active materials (such as Si). For example, Si particles may be dispersed within carbon particles. For example, Si particles may be dispersed within graphite particles. For example, Li silicate particles may be covered by carbon materials (such as amorphous carbon).

[0126] diaphragm

[0127] The separator 20 is capable of separating the positive electrode layer 11 from the negative electrode layer 12. The separator 20 is electrically insulating. The separator 20 may contain at least one selected from, for example, a resin membrane (polymer membrane), an inorganic particle layer, and an organic particle layer. The separator 20 may contain, for example, a resin membrane and an inorganic particle layer.

[0128] The resin membrane is porous. It can include, for example, microporous membranes or nonwoven fabrics. The resin membrane comprises a resin backbone, which can be, for example, a continuous network. Fine pores are formed in the gaps between the resin backbone. The resin membrane allows electrolyte to permeate. The average pore size of the resin membrane can be, for example, less than 1 μm. The average pore size of the resin membrane can be, for example, 0.01~1 μm or 0.1~0.5 μm. The "average pore size" can be determined by mercury porosimetry. The Gurley value of the resin membrane can be, for example, 50~250 s / 100 cm⁻¹. 3 The "Gerley value" can be determined using the Gerley test method.

[0129] The resin membrane may contain at least one selected from, for example, olefin-based resins, polyurethane-based resins, polyamide-based resins, cellulose-based resins, polyether-based resins, acrylic resins, and polyester-based resins. The resin membrane may also contain at least one selected from, for example, polyethylene (PE), polypropylene (PP), polyamide (PA), polyamide-imide (PAI), polyimide (PI), aromatic polyamides, polyphenylene ether (PPE), and their derivatives. The resin membrane can be formed by, for example, stretching or phase separation. The thickness of the resin membrane may be, for example, 5-50 μm or 10-25 μm.

[0130] The resin membrane can have, for example, a single-layer structure. The resin membrane can be composed of, for example, a PE layer. The framework of the PE layer is formed of PE. The PE layer can have a sealing function. The resin membrane can also have, for example, a multi-layer structure. The resin membrane can include, for example, a PP layer and a PE layer. The framework of the PP layer is formed of PP. The resin membrane can also have, for example, a three-layer structure. The resin membrane can be formed by, for example, sequentially stacking a PP layer, a PE layer, and another PP layer. The thickness of the PE layer can, for example, be 5~20 μm. The thickness of the PP layer can, for example, be 3~10 μm.

[0131] The inorganic particle layer can be formed on the surface of the resin membrane. The inorganic particle layer can be formed on only one side of the resin membrane or on both sides. The inorganic particle layer can be formed on the surface opposite to the positive electrode layer 11 or on the surface opposite to the negative electrode layer 12. Furthermore, the inorganic particle layer can be formed on the surface of the positive electrode layer 11 or on the surface of the negative electrode layer 12.

[0132] The inorganic particle layer is porous. It contains inorganic particles, which can also be referred to as "inorganic fillers." Fine pores are formed between the inorganic particles. The thickness of the inorganic particle layer can be, for example, 0.5–10 μm or 1–5 μm. The inorganic particles may contain, for example, heat-resistant materials. An inorganic particle layer containing heat-resistant materials is also called a "HRL (Heat Resistance Layer)." The inorganic particles may contain at least one selected from boehmite, alumina, zirconium oxide, titanium oxide, magnesium oxide, and silicon oxide. The inorganic particles can have any shape. They can be, for example, spherical, rod-shaped, plate-shaped, fibrous, etc. The D50 of the inorganic particles can be, for example, 0.1–10 μm or 0.5–3 μm. The inorganic particle layer may also contain an adhesive. The adhesive may contain, for example, at least one selected from acrylic resins, polyamide resins, fluorinated resins, aromatic polyether resins, and liquid crystal polyester resins.

[0133] The membrane 20 may include, for example, an organic particle layer. The membrane 20 may also include, for example, an organic particle layer instead of a resin membrane. The membrane 20 may include, for example, an organic particle layer instead of an inorganic particle layer. The membrane 20 may also simultaneously include a resin membrane and an organic particle layer. The membrane 20 may simultaneously include an inorganic particle layer and an organic particle layer. The membrane 20 may also include a resin membrane, an inorganic particle layer, and an organic particle layer.

[0134] The thickness of the organic particle layer can be, for example, 0.1~50 μm, 0.5~20 μm, 0.5~10 μm, or 1~5 μm. The organic particle layer contains organic particles. These organic particles can also be referred to as "organic fillers." The organic particles may contain heat-resistant materials. The organic particles may contain at least one material selected from, for example, PE, PP, PTFE, PI, PAI, PA, and aromatic polyamides. The organic particles can be, for example, spherical, rod-shaped, plate-shaped, fibrous, etc. The D50 of the organic particles can be, for example, 0.1~10 μm or 0.5~3 μm.

[0135] The membrane 20 may also include, for example, a hybrid layer. The hybrid layer contains both inorganic and organic particles.

[0136] electrolyte

[0137] The electrolyte is a liquid electrolyte. The electrolyte contains a solute and a solvent. The concentration of the solute can be, for example, 0.5–1 mol / L, 1–1.5 mol / L, 1.5–2 mol / L, 2–2.5 mol / L, or 2.5–3 mol / L. "mol / L" is sometimes expressed as "M". The solute contains a supporting electrolyte (Li salt). The solute can contain, for example, inorganic acid salts, imide salts, oxalate complexes, halides, etc. The solute can contain, for example, at least one selected from 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 their derivatives.

[0138] The electrolyte may contain, for example, a carbonate-based solvent or a carbonate-ester-based solvent. The solvent may contain, for example, cyclic carbonates, chain carbonates, fluorinated carbonates, etc. The solvent may contain, for example, at least one selected from ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene monofluorocarbonate (FEC), difluoroethylene carbonate, 4,4-difluoroethylene carbonate, trifluoroethylene carbonate, perfluoroethylene carbonate, fluoropropylene carbonate, difluoropropylene carbonate, and their derivatives.

[0139] The solvent may contain cyclic carbonates (EC, PC, FEC, etc.) and chain carbonates (EMC, DMC, DEC, etc.). The mixing ratio (volume ratio) of cyclic carbonates and chain carbonates 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".

[0140] The solvent may contain cyclic carbonates (EC, PC, etc.) and fluorinated cyclic carbonates (FEC, etc.). The mixing ratio (volume ratio) of cyclic carbonates and fluorinated cyclic carbonates may be, for example, "cyclic carbonate / fluorinated cyclic carbonate = 99 / 1~90 / 10", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1~1 / 9", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1~7 / 3" or "cyclic carbonate / fluorinated cyclic carbonate = 3 / 7~1 / 9".

[0141] Solvents may include, for example, EC, FEC, EMC, DMC, and DEC. The volume ratios of the components may also satisfy, for example, the relationship expressed by the following formula.

[0142] V EC +V FEC +V EMC +V DMC +V DEC =10

[0143] In the above formula, V EC V FEC V EMC V DMC V DEC These represent the volume ratios of EC, FEC, EMC, DMC, and DEC, respectively.

[0144] The following relationship must be satisfied:

[0145] 1≤V EC ≤4、0≤VFEC ≤3、V EC +V FEC ≤4、

[0146] 0≤V EMC ≤9、0≤V DMC ≤9、0≤V DEC ≤9、6≤V EMC +V DMC +V DEC ≤9.

[0147] For example, it can satisfy 1≤V EC ≤2 or 2≤V EC Relationships ≤3.

[0148] For example, it can satisfy 1≤V FEC ≤2 or 2≤V FEC Relationships ≤4.

[0149] For example, it can satisfy 3≤V EMC ≤4 or 6≤V EMC The relationship is ≤8.

[0150] For example, it can satisfy 3≤V DMC ≤4 or 6≤V DMC The relationship is ≤8.

[0151] For example, it can satisfy 3≤V DEC ≤4 or 6≤V DEC The relationship is ≤8.

[0152] The solvent may have, for example, a composition in volume ratios 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", "EC / FEC / DMC / EMC=1 / 2 / 3 / 4", etc.

[0153] The electrolyte may contain ether-based solvents. The electrolyte may contain, for example, solvents selected from tetrahydrofuran (THF), 1,4-dihydrofuran, etc. At least one of the following: alkylene (DOX), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), hydrofluoroether (HFE), ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and their derivatives.

[0154] The electrolyte may contain optional additives. The amount added (relative to the total mass fraction of the electrolyte) may be, for example, 0.01~5%, 0.05~3%, or 0.1~1%. Additives may include, for example, SEI (solid electrolyte interface) formation promoters, SEI formation inhibitors, gas generators, overcharge preventers, flame retardants, antioxidants, electrode protectants, surfactants, etc.

[0155] Additives may include, for example, those selected from vinylene carbonate (VC), ethylene ethylene carbonate (VEC), 1,3-propanesulfonate lactone (PS), tert-amylbenzene, 1,4-di-tert-butylbenzene, biphenyl (BP), cyclohexylbenzene (CHB), ethylene sulfide (ES), ethylene sulfide (DTD), γ-butyrolactone, phosphazene compounds, and carboxylic acid esters (e.g., methyl formate (MF), methyl acetate (MA), methyl propionate (MP), diethyl malonate (DE)). fluorobenzenes (e.g., monofluorobenzene (FB), 1,2-difluorobenzene, 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.), and fluorotoluenes (e.g., 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2,3-difluorotoluene, 2,4-difluorotoluene, etc.). -Difluorotoluene, 2,5-difluorotoluene, 2,6-difluorotoluene, 3,4-difluorotoluene, octafluorotoluene, etc.), trifluorotoluene (e.g., trifluorotoluene, 2-fluorotrifluorotoluene, 3-fluorotrifluorotoluene, 4-fluorotrifluorotoluene, 2-methyltrifluorotoluene, 3-methyltrifluorotoluene, 4-methyltrifluorotoluene, etc.), fluoroxylene (e.g., 3-fluoro-o-xylene, 4-fluoro-o-xylene, 2-fluoro-m-xylene, 5-fluoro-m-xylene, etc.), The following are included in the list of sulfur-containing heterocyclic compounds (e.g., benzothiazole, 2-methylbenzothiazole, tetrathiofulvalene, etc.), nitrile compounds (e.g., adiponitrile, succinate, etc.), phosphate esters (e.g., trimethyl phosphate, triethyl phosphate, etc.), carboxylic anhydrides (e.g., acetic anhydride, propionic anhydride, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride, etc.), alcohols (e.g., methanol, ethanol, n-propanol, ethylene glycol, diethylene glycol monomethyl ether, etc.), and their derivatives.

[0156] The components described as solutes and solvents can be used as trace components (additives). Additives may contain at least one selected from, for example, LiBF4, LiFSI, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPO2F2, FSO3Li, LiI, LiBr, HFE, DOX, PC, FEC, and their derivatives. Furthermore, the components described as additives can also be used as both solute and solvent.

[0157] The electrolyte may contain ionic liquids. Ionic liquids may contain, for example, salts selected from sulfonium salts, ammonium salts, pyridinium salts, piperidine salts, pyrrolidine salts, morpholine salts, etc. Salt, imidazole At least one of salts and their derivatives.

[0158] In some embodiments of this invention, the battery may comprise a gel electrolyte. That is, the battery may be a polymer battery. The gel electrolyte may comprise an electrolyte and a polymeric material. The polymeric material may form a polymeric matrix. The polymeric material may comprise, for example, at least one selected from PVdF, PVdF-HFP, polyacrylonitrile (PAN), PVdF-PAN, polyethylene oxide (PEO), polyethylene glycol (PEG), and derivatives thereof.

[0159] -All-solid-state batteries-

[0160] In some embodiments, the battery may be an all-solid-state battery. An all-solid-state battery may have a bipolar structure. An all-solid-state battery includes a solid electrolyte in place of the electrolyte and separator 20. The solid electrolyte may also be contained within the positive electrode layer 11 and the negative electrode layer 12. The solid electrolyte layer, in place of the separator 20, 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.

[0161] Solid electrolytes can also be, for example, powders or granules. The D50 of a solid electrolyte can 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 a solid electrolyte can also be, for example, less than 5 μm, less than 4 μm, less than 3 μm, less than 2 μm, or less than 1 μm.

[0162] Solid electrolytes may include at least one selected from, for example, sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, hydride solid electrolytes and nitride solid electrolytes.

[0163] The sulfide solid electrolyte may contain at least one selected from amorphous phases, crystalline phases, and glass-ceramic (crystalline glass) phases. The crystalline phase may be, for example, argyroclase-type, LGPS-type, etc. The sulfide solid electrolyte contains Li and sulfur (S). In addition to Li and S, the sulfide solid electrolyte may also contain optional components.

[0164] Sulfide solid electrolytes may contain, for example, compounds selected from 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 At least one of Li3PS4 and Li7PS6.

[0165] For example, "LiI-LiBr-Li3PS4" indicates a sulfide solid electrolyte produced by mixing LiI, LiBr, and Li3PS4 in any molar ratio. Sulfide solid electrolytes can be produced, for example, by a mechanochemical method. The mixing ratio can also be determined by adding numbers before each raw material. For example, "10LiI-15LiBr-75Li3PS4" indicates a mixing ratio of "LiI / LiBr / Li3PS4 = 10 / 15 / 75 (molar ratio)".

[0166] Sulfide solid electrolytes can have compositions, for example, represented by the following general formula.

[0167] xLi2S-(1-x)P2S5

[0168] In the formula, x can be greater than 0, greater than 0.1, greater than 0.2, greater than 0.25, greater than 0.3, greater than 0.4, greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.75, greater than 0.8, or greater than 0.9. x can also be less than 1, less than 0.9, less than 0.8, less than 0.7, less than 0.75, less than 0.6, less than 0.5, less than 0.4, less than 0.3, less than 0.2, or less than 0.1. For example, when x = 0.75, "xLi2S-(1-x)P2S5" can have the composition of Li3PS4.

[0169] Sulfide solid electrolytes can have compositions, for example, represented by the following general formula.

[0170] yLiI-zLiBr-(100-yz)[xLi2S-(1-x)P2S5]

[0171] In the formula, x can be, for example, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.75 or higher, 0.8 or higher, or 0.9 or higher. x can also be, for example, less than 1, less than 0.9, less than 0.8, less than 0.75, less than 0.7, or less than 0.6. y can be, for example, 0 or higher, 5 or higher, 10 or higher, 15 or higher, 20 or higher, or 25 or higher. y can also be, for example, less than 30, less than 25, less than 20, less than 15, less than 10, or less than 5. z can be, for example, 0 or higher, 5 or higher, 10 or higher, 15 or higher, or 20 or higher. z can also be, for example, less than 30, less than 25, less than 20, less than 15, less than 10, or less than 5.

[0172] Sulfide solid electrolytes can have compositions, for example, represented by the following general formula.

[0173] Li 7-x-2y PS 6-x-y X y

[0174] In the formula, the relationships “0 < 7-x-2y”, “0 < 6-xy”, “0 ≤ x” and “0 ≤ y” are satisfied. X may contain at least one of, for example, fluorine (F), chlorine (Cl), bromine (Br) and iodine (I).

[0175] Sulfide solid electrolytes can have compositions, for example, represented by the following general formula.

[0176] Li 4-x M 1-x P x S4

[0177] In the formula, x can be greater than 0, greater than or equal to 0.1, greater than or equal to 0.2, greater than or equal to 0.3, greater than or equal to 0.4, greater than or equal to 0.5, greater than or equal to 0.6, greater than or equal to 0.7, greater than or equal to 0.8, or greater than or equal to 0.9. x can be less than 1, less than or equal to 0.9, less than or equal to 0.8, less than or equal to 0.7, less than or equal to 0.6, less than or equal to 0.5, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, or less than or equal to 0.1. M can contain at least one of, for example, selected from Al, Zn, In, Ge, Si, Sn, Sb, Ga, and Bi.

[0178] Sulfide solid electrolytes can have compositions, for example, represented by the following general formula.

[0179] Li 10+x Ge 1+x P 2-x S 12

[0180] In the formula, x can 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 can be, for example, less than 0.7, less than 0.6, less than 0.5, less than 0.4, less than 0.3, less than 0.2, or less than 0.1. The sulfide solid electrolyte represented by the above general formula may contain, for example, a crystalline phase of the LGPS type.

[0181] Halogenated solid electrolytes can have compositions, for example, represented by the following general formula.

[0182] Li 6-na M a X6

[0183] In the formula, n represents the oxidation number of M. For example, M may contain atoms with an oxidation number of +3. For example, M may contain atoms with an oxidation number of +4. For example, M may contain at least one selected from Y, Al, Ti, Zr, Ca, and Mg. For example, the relationship "0 < a < 2" may also be satisfied. X may contain at least one selected from, for example, F, Cl, Br, and I.

[0184] Halogenated solid electrolytes can have compositions, for example, represented by the following general formula.

[0185] Li 3-a Ti a Al 1-a F6

[0186] In the formula, 'a' can be, for example, 0 or above, 0.1 or above, 0.2 or above, 0.3 or above, 0.4 or above, 0.5 or above, 0.6 or above, 0.7 or above, 0.8 or above, or 0.9 or above. 'a' can be, for example, below 1, below 0.9, below 0.8, below 0.7, below 0.6, below 0.5, below 0.4, below 0.3, below 0.2, or below 0.1.

[0187] Halogenated solid electrolytes can have compositions, for example, represented by the following general formula.

[0188] Li3YCl a Br b I 6-a-b

[0189] In the formula, the relationship "0 ≤ a + b ≤ 6" can also be satisfied, for example. 'a' can be 0 or higher, 1 or higher, 2 or higher, 3 or higher, 4 or higher, or 5 or higher. 'b' can be 6 or lower, 5 or lower, 4 or lower, 3 or lower, 2 or lower, or 1 or lower.

[0190] Oxide solid electrolytes may contain, for example, those selected from LiNbO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, La 2 / 3-x Li 3x TiO3 and Li7La3Zr2O 12 At least one of the following. Hydride solid electrolytes may contain, for example, LiBH4. Nitride solid electrolytes may contain, for example, Li3N, Li3BN2, etc.

[0191] [Example]

[0192] -Manufacturing of positive electrode active material-

[0193] Various positive electrode active materials are manufactured through the following steps.

[0194] (a) Formation of slurry

[0195] Various positive electrode active materials are manufactured through the following steps. Following the formula "Li 1.04 Mn 0.6 Fe 0.4 As shown in the composition ratio of "PO4", weigh lithium hydroxide monohydrate, manganese carbonate, iron phosphate, and lithium dihydrogen phosphate. Weigh glucose at a mass fraction of 8% relative to the total mass of the raw materials. Mix the weighed materials with water to form a slurry. The solids concentration of the slurry is 30% by mass. Perform wet milling to achieve a D50 of 0.30 μm.

[0196] (b) Granulation

[0197] Secondary particles are formed by spray drying the slurry. The basic settings of the spray dryer are described below.

[0198] Inlet temperature: 250℃

[0199] Exhaust port temperature: 115±15℃

[0200] Inhalation pressure: 2.0 MPa

[0201] Nozzle pressure of the spray nozzle: 0.2±0.1MPa

[0202] Target value for D50 of secondary particles: 9±1μm

[0203] (c) Firing

[0204] LMFP was synthesized by calcining secondary particles under a nitrogen atmosphere. Figure 7This is the temperature profile during firing. First, the furnace temperature is increased to 200°C at a rate of 3°C / min. This temperature is maintained at 200°C for 1 hour. Next, the furnace temperature is increased to 650°C at a rate of 5°C / min. This temperature is maintained at 650°C for 5 hours. Afterward, the furnace temperature is cooled to 400°C at a rate of 2°C / min. Finally, the furnace temperature is cooled to room temperature at a rate of 15°C / min.

[0205] Figure 8 This is a table showing the experimental results. Based on the above process, by changing various conditions (such as the degree of wet grinding of the slurry, the holding time during firing, the heating rate, the cooling rate, the amount of carbon source added, etc.), positive electrode active materials No.1 to No.17 can be manufactured.

[0206] -evaluate-

[0207] Making button units

[0208] A mixture is formed by combining a positive electrode active material, a conductive material (acetylene black), and a binder (PVdF). The mixing ratio (mass ratio) is "positive electrode active material / conductive material / binder = 92 / 5 / 3". The mixture is dispersed in a dispersion medium (N-methyl-2-pyrrolidone) to form a paste. The solids concentration of the paste is 50% by mass fraction. The paste is coated onto the surface of an Al foil and dried, thereby forming the positive electrode layer. The density of the positive electrode layer is adjusted to 1.8 g / cm³ by rolling. 3 This process forms the positive electrode plate. The positive electrode plate is then subjected to vacuum drying at 120°C for 12 hours. After drying, a disc sample (diameter: 14 mm) is removed from the positive electrode plate through punching.

[0209] Button units were assembled inside the glove box. The unit structure is described below.

[0210] Working electrode: Disk sample (positive electrode)

[0211] Counter electrode: Li foil

[0212] Separator: Polymer porous membrane

[0213] Electrolyte: EC / DMC = 3 / 7 (volume ratio), LiPF6 (1 mol / L)

[0214] Output characteristics

[0215] Determine the DCIR using the following steps. A lower DCIR generally indicates better output characteristics.

[0216] Perform the initial charge and discharge of the button cell under the following conditions.

[0217] Method: Constant Current-Constant Voltage (CCCV) method

[0218] Magnification: 0.01C

[0219] Lower limit voltage: 3.0V

[0220] Upper voltage limit: 4.3V

[0221] Furthermore, "C" is a notation representing the current multiplier (time rate). At a multiplier of 1C, it represents the theoretical capacity of a button cell flowing for 1 hour.

[0222] Next, the button cell was charged at a rate of 0.1C until it reached 60% SOC (State of Charge). At room temperature, the button cell was discharged at a rate of 1C. The voltage was measured 10 seconds after the start of discharge. Similarly, the voltages were measured at rates of 2C, 3C, 4C, and 5C. In a two-dimensional coordinate system with current on the horizontal axis and voltage on the vertical axis, the absolute value of the slope of the straight line obtained by plotting the measurement results is considered as DCIR. Figure 8 The DCIR values ​​of each sample are relative to the DCIR of No.1, which is 100.

[0223] -result-

[0224] like Figure 8 As shown in Table 1, when the width "X" of the first region is 0.5~20nm in the line profile of the primary particle P, an improved output characteristic can be observed.

[0225] like Figure 8 As shown in Table 2, when the line profile of the secondary particle P rises and falls, and the average spacing "Y" between the valleys is 11~290nm, a tendency to improve the output characteristics can be observed.

[0226] like Figure 8 As shown in Table 3, in the line profile of the secondary particle P, when the line profile rises and falls, and the peak-to-valley ratio "Z" is below 0.90, a tendency to improve the output characteristics can be observed.

[0227] like Figure 8 As shown in Table 3, in the line profile of the secondary particle P, when the line profile rises and falls, and the peak-to-valley ratio "Z" is below 0.69, a tendency to improve the output characteristics can be observed.

[0228] like Figure 8 As shown in Table 3, in the line profile of the secondary particle P, when the line profile rises and falls, and the peak-to-valley ratio "Z" is below 0.48, a tendency to improve the output characteristics can be observed.

Claims

1. A positive electrode active material comprising primary particles, The primary particles contain olivine-type phosphate compounds. In the cross-section of the primary particle, the line profile of the phosphorus signal intensity obtained based on transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) line analysis along the diameter direction of the primary particle includes a first region and a second region. The first region is located at both ends of the primary particle. The second region is located between the first regions. The signal strength of phosphorus in the first region is lower than that in the second region, and, The width of the first region is 0.5~20nm.

2. The positive electrode active material according to claim 1, Includes secondary particles, The secondary particle comprises a plurality of the primary particles. In the cross-section of the secondary particle, the line profile of the phosphorus signal intensity obtained based on TEM-EDS line analysis along the diameter direction of the secondary particle repeatedly rises and falls.

3. The positive electrode active material according to claim 2, In the line profile, the average spacing between the valleys of phosphorus signal intensity is 11~290 nm.

4. The positive electrode active material according to claim 2, In the line profile, the ratio of the minimum signal strength of phosphorus to the maximum signal strength of phosphorus is less than 0.

90.

5. The positive electrode active material according to claim 4, The ratio of the minimum value to the maximum value is less than 0.

69.

6. The positive electrode active material according to claim 5, The ratio of the minimum value to the maximum value is less than 0.

48.

7. The positive electrode active material according to any one of claims 1 to 6, The olivine-type phosphate compound comprises at least one selected from lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate.

8. An electrode comprising a positive electrode layer, The positive electrode layer comprises the positive electrode active material according to any one of claims 1 to 6.

9. A battery comprising the electrode of claim 8.

10. The battery according to claim 9, having a bipolar structure.

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