Positive electrode material composition, secondary battery and electrical device

Abstract

The present application provides a positive electrode material composition for improving the high-temperature storage performance of batteries, a secondary battery, and an electric device. The positive electrode material composition includes a phosphate-based positive electrode material and a ternary positive electrode material, where the weight of the phosphate-based positive electrode material is denoted as W1 and the weight of the ternary positive electrode material is denoted as W2, where α = W1 / (W1 + W2), and 3%≦α≦50%. The phosphate-based positive electrode material is a single-crystalline material or has a single-crystalline core, and the ternary positive electrode material is a single-crystalline material or has a single-crystalline core. The phosphate-based positive electrode material contains phosphate polyanions, which provides strong material stability, good cycle stability, and a longer lifespan. Meanwhile, the ternary positive electrode material has a relatively high energy density. The phosphate-based positive electrode material is a single crystal material or has a single crystal core, and the ternary-based positive electrode material is a single crystal or has a single crystal core, which further improves the cycle performance of the positive electrode material, and the single crystal BET has a small specific surface area, stable structure, high compression density, and better high-temperature storage performance.

Description

[Technical Field]

[0001] The present application relates to the technical field of batteries, and in particular to positive electrode material compositions, secondary batteries, and electrical devices. [Background technology]

[0002] Lithium-ion batteries are secondary batteries (rechargeable batteries) that rely primarily on the mechanism by which lithium ions move between the positive and negative electrodes. During the charge and discharge process, Li ions repeatedly intercalate and deintercalate between the two electrodes. During charging, Li ions are deintercalated from the positive electrode and inserted into the negative electrode via the electrolyte, leaving the negative electrode in a lithium-rich state, and vice versa during discharge.

[0003] Currently, there are many methods for improving the cycling performance of lithium-ion batteries. These include modifying the positive electrode material by doping or coating it to slow the deterioration of the crystalline structure of the positive electrode material during cycling, or combining positive electrode materials with different advantages to complement each other and improve the cycling performance and energy density of the battery. For example, a lithium iron phosphate-based positive electrode material is combined with a ternary positive electrode material. However, even after combining the two, the ternary positive electrode material is usually still the main component. Due to the limited cycling stability of the ternary positive electrode material, the improvement in the cycling stability of the composition is insufficient, especially in terms of high-temperature storage performance. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application provides a positive electrode material composition for improving the high-temperature storage performance of a battery, a secondary battery, and an electric device. [Means for solving the problem]

[0005] According to a first aspect of the present application, there is provided a cathode material composition comprising a phosphate-based cathode material and a ternary cathode material, wherein the weight of the phosphate-based cathode material is designated W1, the weight of the ternary cathode material is designated W2, α=W1 / (W1+W2), and 3%≦α≦50%, the phosphate-based cathode material is a single crystal material or has a single crystal core, and the ternary cathode material is single crystal or has a single crystal core.

[0006] Phosphate-based positive electrode materials have low energy density, but their material structure uses phosphate polyanion materials, which provides strong stability, good cycling stability, and long life. Ternary positive electrode materials have relatively high energy density, but the layered transition metal oxides experience material losses such as phase change, Li-Ni mixing, oxygen release, and structural collapse during cycling, resulting in a shorter lifespan than phosphate-based positive electrode materials. The phosphate-based positive electrode materials of the present application are single-crystalline materials or have a single-crystalline core, while the ternary positive electrode materials are single-crystalline or have a single-crystalline core, which further improves the cycling performance of the positive electrode materials. The single crystals have a small BET specific surface area, stable structure, high compression density, and better high-temperature storage performance.

[0007] In any embodiment of the first aspect, the particle size distribution of the positive electrode material composition satisfies the relationship 8>Aα+B(1-α)>1, where A is the D of the phosphate-based positive electrode material. V 50, and B is the D of the ternary positive electrode material V 50. The particle size fitting effect between the phosphate-based positive electrode material and the ternary-based positive electrode material is further improved, thereby significantly improving the high-temperature storage performance.

[0008] In any embodiment of the first aspect, the D of the phosphate-based positive electrode material V 50 is 0.8 to 8 μm, and DV 90 <30 μm, thereby improving the processing feasibility and high temperature stability of the cathode material composition.

[0009] In the first embodiment of the first aspect, the BET specific surface area of ​​the phosphate-based positive electrode material is 8 to 20 m2 / g, which can further improve the structural stability, compaction density, and high-temperature storage performance of the positive electrode material composition.

[0010] In a first embodiment of the first aspect, the chemical formula of the phosphate-based positive electrode material is Li 1+x Mn 1-y A y P 1-z R z O4, in which x is any number in the range of -0.100 to 0.100, y is any number in the range of 0.001 to 0.500, and z is any number in the range of 0.001 to 0.100, and the values ​​of x, y, and z satisfy the following condition, i.e., to keep the chemical formula electrically neutral; A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and optionally, A includes one or more elements selected from the group consisting of Fe, Ti, V, Ni, Co, and Mg; R includes one or more elements selected from the group consisting of B, Si, N, S, F, Cl, and Br, and optionally, R includes one element selected from the group consisting of B, Si, N, and S. Doping the phosphate-based material with element A and element R contributes to improving the structural stability of the phosphate-based positive electrode material and the rate performance of the secondary battery containing it.

[0011] In a second embodiment of the first aspect, the chemical formula of the phosphate-based positive electrode material is Li a A x Mn 1-y B y P 1-z C z O 4-n D nwherein A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from the group consisting of B (boron), S, Si, and N; D includes one or more elements selected from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; and n is selected from the range of 0.001 to 0.1; and the phosphate-based positive electrode material is electrically neutral. By simultaneously doping the specific elements at the four positions in specific amounts, the rate performance, cycle performance and / or high temperature stability of the phosphate-based positive electrode material can be significantly improved.

[0012] In any embodiment of the first aspect, optionally, the phosphate-based positive electrode material includes a single crystal core and a coating layer coating the single crystal core, the single crystal core having the chemical formula Li 1+x Mn 1-y A y P 1-z R z O4 or chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n The coating layer is optionally one or more layers of pyrophosphate, phosphate, and carbon. The functional coating layer can effectively suppress the elution of transition metals and reduce surface side reactions of the phosphate-based positive electrode material.

[0013] In any embodiment of the first aspect, the D of the ternary positive electrode material v 50 is 2 to 8 μm, and D v 99≦18μm. The particle size affects the gram capacity after mixing, and the D v 50 and D vControlling 99 contributes to shortening the diffusion path of lithium ions and the bulk-phase diffusion resistance, reducing the polarization of the material, and the improvement effect on the capacity after mixing is particularly remarkable.

[0014] In any of the embodiments of the first aspect, the BET specific surface area of the ternary cathode material is 0.42 - 1.5 m 2 / g. The structural stability, crimp density, and high-temperature storage performance of the cathode material can be further improved.

[0015] In any of the embodiments of the first aspect, the ternary cathode material is a single-crystalline NCM ternary cathode material or a single-crystalline NCA ternary cathode material. Optionally, the Ni molar content in the ternary cathode material is 50% - 99.5%, and the Co molar content is 0.5% - 49.5%. Further optionally, the Ni molar content is 60% - 88%, and the Co molar content is 5% - 35%. The Ni molar content affects the performance of the capacity of the ternary cathode material and has a great impact on improving the energy density of the composite material. The Co molar content improves the electronic conductivity and ionic conductivity of the system, thereby effectively improving the charging performance of the ternary cathode material.

[0016] In any of the embodiments of the first aspect, the ternary cathode material has the chemical formula Li a’ Ni b’ Co C’ M1 d’ M2 e’ O f’ R’ g’ where 0.75 ≤ a’ ≤ 1.2, 0 < b’ < 1, 0 < c’ < 1, 0 < d’ < 1, 0 ≤ e’ ≤ 0.2, 1 ≤ f’ ≤ 2.5, 0 ≤ g’ ≤ 1, f’ + g’ ≤ 3, M1 is Mn element and / or Al element, M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R’ is one or more elements selected from N, F, S, Cl. By using element doping, the cycle performance and rate performance of the ternary cathode material are improved.

[0017] According to a second aspect of the present invention, there is provided a secondary battery including a positive electrode piece containing a positive electrode active material that is any one of the positive electrode material compositions according to the first aspect. The secondary battery having the positive electrode material composition of the present invention not only has high energy density and cycle performance, but also effectively improves high-temperature storage performance.

[0018] According to a third aspect of the present application, there is provided an electric device including a secondary battery selected from the secondary batteries of the second aspect, which electric device has better operational stability at high temperatures. [Brief explanation of the drawings]

[0019] In order to more clearly explain the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings used in the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can further obtain other drawings according to the drawings without any creative work. [Figure 1] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Figure 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1. [Figure 3] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application; [Figure 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of an electrical device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following detailed description of the embodiments of the present application will be given in conjunction with the drawings and examples. The detailed description of the embodiments and the drawings below are used to exemplify the principles of the present application, but are not intended to limit the scope of the present application, i.e., the present application is not limited to the described examples.

[0021] Hereinafter, with reference to the drawings as appropriate, embodiments specifically disclosing the positive electrode material composition, secondary battery, and electrical device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters and repeated description of substantially identical configurations may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the scope of the claims.

[0022] The "ranges" disclosed herein are defined by lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of that particular range. Such defined ranges may be inclusive or exclusive of their endpoints and may be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are recited and maximum range values ​​of 3, 4, and 5 are recited, all of the following ranges are contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, a numerical range "a to b" represents shorthand notation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" are recited in the text, and "0 to 5" is simply a shorthand notation for combinations of these numbers. Furthermore, when a parameter is described as an integer ≧2, this is equivalent to disclosing that the parameter is an integer, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0024] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0025] Unless otherwise specified, all steps in the present application may be performed sequentially or randomly, but are preferably performed sequentially. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, when the method described above may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0026] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open or closed. For example, the terms "comprise" and "comprises" may further include or include other components not listed, or may include or include only the listed components.

[0027] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0028] [Secondary battery] Secondary batteries, also called rechargeable batteries or storage batteries, refer to batteries that can be continuously used by activating the active materials by charging them after discharging.

[0029] A typical secondary battery contains positive and negative electrode pieces, a separator film, and an electrolyte. During the charge and discharge process, active ions (e.g., lithium ions) are repeatedly inserted and removed between the positive and negative electrode pieces. The separator film is placed between the positive and negative electrode pieces and primarily serves to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through. The electrolyte is placed between the positive and negative electrode pieces and primarily serves to conduct the active ions.

[0030] [Cathode material] One embodiment of the present application provides a cathode material composition including a phosphate-based cathode material and a ternary cathode material, wherein the weight of the phosphate-based cathode material is denoted as W1, the weight of the ternary cathode material is denoted as W2, α=W1 / (W1+W2), and 3%≦α≦50%, the phosphate-based cathode material is a single crystal material or has a single crystal core, and the ternary cathode material is a single crystal or has a single crystal core.

[0031] Phosphate-based positive electrode materials have low energy density, but their material structure uses phosphate polyanion materials, which provides strong stability, good cycling stability, and long life. Ternary positive electrode materials have relatively high energy density, but the layered transition metal oxides experience material losses such as phase change, Li-Ni mixing, oxygen release, and structural collapse during cycling. As a result, the life of ternary positive electrode materials is shorter than that of phosphate-based positive electrode materials. The phosphate-based positive electrode materials of the present application are single-crystalline materials or have a single-crystalline core, while the ternary positive electrode materials are single-crystalline or have a single-crystalline core, which further improves the cycling performance of the positive electrode materials. Furthermore, the BET properties of single crystals are small, structurally stable, and have high compression density, resulting in better high-temperature storage performance.

[0032] As α increases within the above range, the cycle performance of the positive electrode material composition improves.

[0033] Explanation of terms: Phosphate-based cathode materials: Not only does it contain LiMnPO4, but also lithium manganese iron phosphate (LiMn x Fe 1-xPO4)-based cathode materials, lithium aluminum manganese phosphate (LiMn x Al 1-x PO4)-based positive electrode materials, such as LiMn x Fe 1-x PO4, doped LiMn x Fe 1-x PO4, LiMn with coating layer x Fe 1-x It is PO4.

[0034] Polycrystalline: The positive electrode material exists in the form of aggregates.

[0035] Monocrystalline: There is no agglomeration of primary particles, and the particle size is generally 10 to 50 times larger than the particle size of the primary particles of agglomerated materials (polycrystalline), with a high degree of internal crystallinity and no excess porosity.

[0036] If a positive electrode material composition is present in the positive electrode piece, the positive electrode piece is cut by argon ion polishing, and elemental analysis is performed on the polished surface to compare the ratios of main elements of the phosphate-based positive electrode material and the ternary-based material, and the ratios are used to correspond to the weights.

[0037] In some embodiments, the particle size distribution of the positive electrode material composition satisfies the relationship 8>Aα+B(1-α)>1, where A is the DV of the phosphate-based positive electrode material. 50 and B is the DV of the ternary cathode material. 50 The particle size fitting effect between the phosphate-based positive electrode material and the ternary-based positive electrode material is further improved, thereby significantly improving the high-temperature storage performance.

[0038] In some embodiments, the D of the phosphate-based positive electrode material V 50 is 0.8 to 8 μm, for example, 0.8 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, and D V 90<30 μm, thereby improving the process feasibility and high temperature stability of the positive electrode material composition.

[0039] In some embodiments, the BET specific surface area of ​​the phosphate-based positive electrode material is 8 to 20 m 2 / g, for example, 8m 2 / g, 10m 2 / g, 12m 2 / g, 15m 2 / g or 20m 2 / g, which can further improve the structural stability, compaction density, and high-temperature storage performance of the positive electrode material composition.

[0040] In some embodiments, the formula of the phosphate-based positive electrode material is Li 1+x Mn 1-y A y P 1-Z R Z O4, in which x is any number in the range of -0.100 to 0.100, y is any number in the range of 0.001 to 0.500, and z is any number in the range of 0.001 to 0.100, and the values ​​of x, y, and z satisfy the following condition, i.e., to keep the chemical formula electrically neutral; A comprises one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and may comprise one or more elements selected from the group consisting of Fe, Ti, V, Ni, Co, and Mg; R is one or more elements selected from the group consisting of B, Si, N, S, F, Cl, and Br; and optionally, R is one element selected from the group consisting of B, Si, N, and S. Element A doped into the manganese site of lithium manganese iron phosphate contributes to reducing the crystal lattice change rate of lithium manganese iron phosphate during the lithium de-lithiation process, improving the structural stability of the lithium manganese iron phosphate cathode material, significantly reducing manganese dissolution, and reducing oxygen activity on the particle surface. Element R doped into the phosphate site contributes to changing the difficulty of the Mn-O bond length change, thereby reducing the lithium ion migration barrier, facilitating lithium ion migration, and improving the rate performance of secondary batteries.

[0041] In some embodiments, the formula of the phosphate-based positive electrode material is Li a Ax Mn 1-y B y P 1-z C z O 4-n D n wherein A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from the group consisting of B (boron), S, Si, and N; D includes one or more elements selected from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, and is, for example, 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01; and x is 0.0 y is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, and y is selected from the range of 0.001 to 0.5, for example, 0.001, 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, The phosphate-based positive electrode material is electrically neutral. A, B, C, and D are elements doped at the Li, Mn, P, and O sites of the compound LiMnPO4, respectively. While not wishing to be bound by theory, it is currently believed that the improved performance of the phosphate-based material is related to a reduction in the crystal lattice change rate of the phosphate-based material during the lithium desorption process and a decrease in surface activity. Reducing the crystal lattice change rate reduces the difference in the crystal lattice constants between the two phases at the grain boundary, reducing interfacial stress and enhancing Li desorption. +This can enhance the transport capability at the interface, thereby improving the rate performance of the positive electrode active material. High surface activity is prone to serious interfacial side reactions, resulting in gas generation, electrolyte depletion, and interfacial breakdown, thereby affecting battery performance such as cycling. The above-mentioned phosphate-based positive electrode material reduces the crystal lattice change rate through doping at the Li and Mn sites. Doping at the Mn site effectively reduces surface activity, thereby suppressing Mn dissolution and interfacial side reactions between the positive electrode active material and the electrolyte. Doping at the P site accelerates the rate of change of the Mn-O bond length, reducing the small polaron migration barrier of the material, thereby benefiting electronic conductivity. Doping at the O site has an excellent effect on reducing interfacial side reactions. Doping at the P and O sites also affects the Mn dissolution and kinetic performance of antisite defects. Therefore, doping reduces the concentration of antisite defects in the material, improving the kinetic performance and gram capacity of the material, and can also change the particle morphology to increase the packing density. The applicant unexpectedly discovered the following: That is, by simultaneously doping the Li site, Mn site, P site, and O site of the compound LiMnPO4 with specific elements in specific amounts, it is possible to obtain a clearly improved rate performance, and at the same time, to significantly reduce the dissolution of Mn and the elements doped into the Mn site, thereby obtaining significantly improved cycle performance and / or high temperature stability, and also to improve the gram capacity and packed density of the material.

[0042] In some embodiments, the phosphate-based positive electrode material optionally includes a single crystal core and a functional coating layer coating the single crystal core, the single crystal core having the chemical formula Li 1+x Mn 1-y A y P 1-z R zThe functional coating layer is optionally one or more layers of pyrophosphate, phosphate, and carbon. The high transition metal migration barrier (>1 eV) in pyrophosphate effectively inhibits transition metal dissolution. Phosphate has excellent lithium ion conductivity and can reduce the miscellaneous lithium content on the surface. The carbon layer effectively improves the conductivity and desolvation ability of LiMnPO4 and also acts as a "barrier" to further hinder the migration of manganese ions into the electrolyte and reduce corrosion of the active material by the electrolyte. At the same time, the carbon layer can also optimize the conductive network around the ternary positive electrode material in the mixture, improving the mixing uniformity of the phosphate-based positive electrode material and the ternary positive electrode material.

[0043] In some embodiments, the D of the ternary positive electrode material v 50 is 2 to 8 μm, and D v 99≦18μm. The particle size affects the gram capacity after mixing, and the D v 50 and D v Controlling 99 contributes to shortening the diffusion path of lithium ions and the bulk phase diffusion resistance, reducing the polarization of the material, and the improvement in capacity after mixing is particularly significant.

[0044] In some embodiments, the BET specific surface area of ​​the ternary positive electrode material is 0.42 to 1.5 m 2 / g. The structural stability, compaction density, and high-temperature storage performance of the positive electrode material composition can be further improved.

[0045] In some embodiments, the ternary cathode material is a single-crystalline NCM ternary cathode material or a single-crystalline NCA ternary cathode material. Optionally, the molar content of Ni in the ternary cathode material is 50% to 99.5%, for example 50%, 55%, 60%, 70%, 80%, 88%, 90%, 95% or 99.5%, and the molar content of Co is 0.5% to 49.5%, for example 0.5%, 5%, 10%, 20%, 30%, 35%, 40%, 45% or 50%. Further optionally, the molar content of Ni is 60% to 88%, and the molar content of Co is 5% to 35%. The molar content of Ni affects the performance of the capacity of the ternary cathode material and greatly affects the improvement of the energy density of the composite material. The molar content of Co improves the electronic conductivity and ionic conductivity of the system, thereby effectively improving the charging performance of the ternary cathode material.

[0046] In some embodiments, the ternary cathode material has the chemical formula Li a’ Ni b’ Co c’ M1 d’ M2 e’ O f’ R’ g’ where 0.75 ≤ a’ ≤ 1.2, 0 < b’ < 1, 0 < c’ < 1, 0 < d’ < 1, 0 ≤ e’ ≤ 0.2, 1 ≤ f’ ≤ 2.5, 0 ≤ g’ ≤ 1, f’ + g’ ≤ 3, M1 is Mn element and / or Al element, M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R’ is one or more elements selected from N, F, S, Cl. By using element doping, the cycle performance and rate performance of the ternary cathode material are improved.

[0047] Both the phosphate-based cathode material and the ternary cathode material of the present application may be commercialized materials or may be manufactured. For example, they are a series of single-crystalline manganese iron lithium phosphate cathode materials produced by Shenzhen Defang Nano Science and Technology Co., Ltd. (abbreviated as Defang Nano in the examples), and a series of single-crystalline ternary cathode materials produced by Ningbo Rongbai New Energy Science and Technology Co., Ltd. (abbreviated as Rongbai Science and Technology in the examples).

[0048] [Positive electrode piece] A positive electrode piece generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0049] As an example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0050] In some embodiments, the positive electrode current collector can be a metal foil piece or a composite current collector. For example, the metal foil piece can be aluminum foil. The composite current collector can include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0051] In some embodiments, the positive electrode active material employs any one of the positive electrode material compositions provided herein.

[0052] In some embodiments, the positive electrode film layer may further optionally include an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0053] In some embodiments, the positive electrode film layer may further optionally include a conductive agent, for example, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0054] In some embodiments, the positive electrode pieces can be manufactured as follows: the components for manufacturing the positive electrode pieces, such as the positive electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, and the positive electrode slurry is applied to a positive electrode current collector. After undergoing processes such as drying and cold pressing, the positive electrode pieces can be obtained.

[0055] [Negative electrode piece] The negative electrode piece includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0056] As an example, the negative electrode current collector has two surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on one or both of the two facing surfaces of the negative electrode current collector.

[0057] In some embodiments, the negative electrode current collector may be a metal foil piece or a composite current collector. For example, the metal foil piece may be copper foil. The composite current collector may include a polymeric substrate and a metal layer formed on at least one surface of the polymeric substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymeric substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0058] In some embodiments, the negative electrode active material can be any negative electrode active material known in the art for batteries. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin-oxygen compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0059] In some embodiments, the negative electrode film layer may further optionally include an adhesive. For example, the adhesive may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0060] In some embodiments, the negative electrode film layer may further optionally include a conductive agent, for example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0061] In some embodiments, the negative electrode film layer may further optionally contain other additives, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

[0062] In some embodiments, the negative electrode pieces can be manufactured as follows: the above-mentioned components for manufacturing the negative electrode pieces, such as the negative electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, and the negative electrode slurry is applied to a negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode pieces can be obtained.

[0063] [Electrolyte] The electrolyte serves to conduct ions between the positive and negative electrode pieces. The present application does not specifically limit the type of electrolyte, and it can be selected as needed. For example, the electrolyte may be liquid, gel, or completely solid.

[0064] In some embodiments, the electrolyte is a liquid and includes an electrolyte salt and a solvent.

[0065] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorobisoxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0066] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0067] In some embodiments, the electrolyte solution optionally further contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0068] [Separator film] In some embodiments, the secondary battery further includes a separator film. The present application does not particularly limit the type of separator film, but any separator film having a known porous structure and good chemical and mechanical stability can be selected.

[0069] In some embodiments, the separator film may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film may be a single-layer thin film or a multi-layer composite thin film, without any particular limitation. When the separator film is a multi-layer composite thin film, the materials of the layers may be the same or different, without any particular limitation.

[0070] In some embodiments, the positive electrode strips, negative electrode strips, and separator film can be fabricated into an electrode assembly by a winding or lamination process.

[0071] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and electrolyte.

[0072] In some embodiments, the exterior packaging of the secondary battery may be a hard casing, such as a hard plastic casing, an aluminum case, a steel case, etc. The exterior packaging of the secondary battery may be a pouch, such as a bag-type pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0073] The present application does not particularly limit the shape of the secondary battery, but it may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows a secondary battery 5 having a rectangular structure as an example.

[0074] In some embodiments, referring to FIG. 2 , the outer packaging may include a casing 51 and a cover plate 53. The casing 51 includes a base plate and a side plate connected to the base plate, which together form a surrounding accommodating chamber. The casing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening and close the accommodating cavity. The positive electrode piece, the negative electrode piece, and the separator film can be formed into an electrode assembly 52 by a winding or lamination process. The electrode assembly 52 is sealed in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The secondary battery 5 may include one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0075] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0076] 3 shows a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, the plurality of secondary batteries 5 may be arranged in order along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fastening members.

[0077] Optionally, the battery module 4 may further include an exterior case having an accommodating space, and the plurality of secondary batteries 5 are accommodated in the accommodating space.

[0078] In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0079] 4 and 5 show a battery pack 1 as an example. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper case 2 and a lower case 3, and the upper case 2 is attached to the lower case 3 as a cover, forming a sealed space for accommodating the battery modules 4. A plurality of battery modules 4 may be installed in the battery box as desired.

[0080] The present application also provides an electric device including at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack may be used as a power source for the electric device or as an energy storage unit for the electric device. The electric device includes, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0081] The electric device can be selected as a secondary battery, a battery module or a battery pack according to the needs of the use.

[0082] 6 shows an example of an electric device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power and high energy density from secondary batteries, a battery pack or a battery module can be used.

[0083] [Example] The following examples are provided for illustrative purposes only and are not intended to limit the scope of the present application. Unless specific techniques or conditions are described in the examples, they may be performed in accordance with techniques or conditions described in technical documents or in accordance with the product instructions. Unless the manufacturer of the reagents or equipment used is specified, they may be commercially available products.

[0084] The source of the positive electrode material is the phosphate-based positive electrode material LiMn 0.6 Fe 0.4 PO4 is purchased from Defang Nano, the ternary positive electrode material is purchased from Yongbai Science and Technology, and the remaining positive electrode materials are prepared by the following method:

[0085] Production example 1: Li 0.999 Mn 0.60 Fe 0.393 V 0.004 Co 0.003 P 0.999 S 0.001 O4 Production (1) Preparation of co-doped lithium iron manganese phosphate cores Preparation of Fe-, Co-, and V-codoped manganese oxalate: 689.5 g of manganese carbonate (MnCO), 455.2 g of ferrous carbonate (FeCO), 4.6 g of cobalt sulfate (CoSO), and 4.9 g of vanadium dichloride (VCl) were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reactor, and 5 L of deionized water and 1260.6 g of oxalic acid dihydrate (CHO.2HO) were added. The reactor was heated to 80°C and stirred at 600 rpm for 6 hours until the reaction was complete (no more bubbles were generated). This yielded a manganese oxalate suspension codoped with Fe, Co, V, and S. The suspension was then filtered, and the filter cake was dried at 120°C, then polished using an air mill, polished, classified, and sieved through a 325 mesh sieve to obtain Fe, Co, and V co-doped manganese(II) oxalate dihydrate particles.

[0086] Preparation of Fe, Co, V, and S co-doped lithium manganese iron phosphate: 1793.4 g of the manganese(II) oxalate dihydrate particles obtained in the previous step, 369.0 g of lithium carbonate (Li2CO3), 1.6 g of 60% dilute sulfuric acid (60% H2SO4), and 1148.9 g of ammonium dihydrogen phosphate (NH4H2PO4) were added to 20 L of deionized water and stirred for 10 hours to obtain a uniformly mixed slurry. The slurry was then transferred to a spray-drying equipment for spray drying and granulation. The drying temperature was set to 250 °C for 4 hours to obtain a powder material. The powder material was sintered at 700 °C for 4 hours in a protective atmosphere of nitrogen gas (90 vol%) and hydrogen gas (10 vol%) to obtain 1572.1 g of Fe, Co, V, and S co-doped lithium manganese iron phosphate.

[0087] Production example 2: Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 Manufacturing 1) Preparation of positive electrode active material Preparation of doped manganese oxalate: 1.3 mol of MnSO₄·H₂O and 0.7 mol of FeSO₄·H₂O were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reactor, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (hereinafter referred to as oxalic acid) were added. The reactor was heated to 80°C and stirred at 600 rpm for 6 hours. The reaction was completed (no more bubbles were generated), and a suspension of Fe-doped manganese oxalate was obtained. The suspension was then filtered, and the filter cake was dried at 120°C, polished, classified, and passed through a 325-mesh sieve. If necessary, the mixture was polished to the target particle size to obtain Fe-doped manganese oxalate particles.

[0088] Preparation of doped manganese iron lithium phosphate: 1 mol of the above manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO4)3, an 85% aqueous solution of phosphoric acid containing 0.999 mol of phosphoric acid, 0.001 mol of H4SiO4, 0.0005 mol of NH4HF2, and 0.005 mol of sucrose were added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was then transferred to a spray drying facility for spray drying and granulation. The drying temperature was set to 250°C and dried for 4 hours to obtain particles. The powder material was sintered at 700°C for 10 hours in a protective atmosphere of nitrogen gas (90% by volume) and hydrogen gas (10% by volume), resulting in a carbon-coated Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 obtained.

[0089] The volumetric particle size distribution and specific surface area of ​​the obtained materials were adjusted by adjusting the reactor heating temperature, the number of sieve openings, and the sintering temperature in the above Production Examples 1 and 2, and the production processes for each material will not be described individually in this application.

[0090] Observation of the appearance of the positive electrode material with a scanning electron microscope confirmed that the lithium iron manganese phosphate positive electrode material and the ternary positive electrode material in each example were single-crystal particles (a single-crystal particle is a single perfect crystalline sphere, while a polycrystalline particle is a large sphere formed by the aggregation of multiple fine primary particles).

[0091] The particle size of the lithium manganese iron phosphate positive electrode material and the ternary positive electrode material in each example was measured by powder laser particle size measurement, referring to the national standard GB / T19077-2016, in which deionized water was used as the solvent and ultrasonic waves were applied for 5 minutes before the measurement.

[0092] Powder specific surface area (BET) measurement: The measurement was performed in accordance with GB / T19587-2004. Before the measurement, the powder was placed in a vacuum drying box and dried at 200°C for ≥2 hours, and the required amount of powder was weighed out to ≥20g.

[0093] Measurement of size of primary particles of powder: The size of primary particles was confirmed by SEM measurement of the powder.

[0094] Gram capacity measurement: The button battery prepared as above was left to stand for 5 minutes in a constant temperature environment of 25°C, discharged at 0.1C to 2.5V, left to stand for 5 minutes, and then charged at a constant current and voltage of 0.1C to 4.3V or 4.25V (Ni content > 70%, upper voltage limit 4.25V). Then, it was charged at a constant voltage of 4.3V or 4.25V until the current became ≦ 0.05mA, and left to stand for 5 minutes. The charge capacity at this time was recorded as C0. Then, it was discharged at 0.1C to 2.5V. The discharge capacity at this time was the initial discharge capacity and recorded as D0.

[0095] The measured discharge capacity value (i.e., initial discharge capacity D0) is divided by the mass of the positive electrode active material of the button cell to obtain the gram capacity of the positive electrode active material.

[0096] The gram capacity, D, of the lithium iron phosphate positive electrode material and the ternary positive electrode material used in the examples V 50, D V 90 and BET specific surface area were recorded in Table 1.

[0097] Table 1 [Table 1A] [Table 1B]

[0098] Of these, NCM-18 is a secondary particle, and the rest are all single crystal particles.

[0099] The compositions of the positive electrode material compositions of the examples and comparative examples are shown in Table 2 (wherein the proportion of LMFP is the mass proportion of LMFP and NCM).

[0100] Table 2 [Table 2]

[0101] The electrical properties were measured by the following methods.

[0102] (1) Manufacturing of mixed electrode stacked batteries: Preparation of mixed positive electrode: The positive electrode active material composition in each of the above examples and comparative examples was used as the positive electrode active material (the mixing ratio was determined by the mass ratio of the two, mA + mB = 100%), and was added to a certain amount of N-methylpyrrolidone (NMP) together with polyvinylidene fluoride (PVDF) and conductive carbon, so that the mass ratio of active material:PVDF:conductive carbon was 90:5:5. The mixture was stirred in a drying chamber to prepare a uniform slurry, and the viscosity was controlled to 3000 to 10000 mPa·S. The slurry was then coated on aluminum foil, dried, and cold pressed to prepare a positive electrode piece.

[0103] Graphite anode fabrication: Artificial graphite was used as the anode active material. Sodium carboxymethyl cellulose (CMC), conductive carbon, and styrene butadiene rubber (SBR) were mixed in a mass ratio of 94:1.5:2:2.5. A certain amount of deionized water was added and stirred in a drying chamber to form a uniform slurry. The viscosity was controlled to 2000-12000 mPa·S. The slurry was coated onto copper foil, and the anode coating mass was matched to the cathode (94% × anode coating mass × graphite gram capacity = 1.15 × 90% × cathode coating mass × mixed cathode gram capacity, where gram capacity refers to the gram capacity after the third cycle of the powder cycle of the lithium half-cell material). After drying and cold pressing, anode pieces were fabricated.

[0104] The electrolyte used was 1 mol / L LiPF6 / (ethylene carbonate (EC) + diethyl carbonate (DEC) + dimethyl carbonate (DMC)) (volume ratio 1:1:1) + 5 wt.% fluoroethylene carbonate (FEC).

[0105] A porous polymer film made of polyethylene (PE) was used as the separator film.

[0106] After undergoing processes such as pole piece punching, tab cleaning, lamination, welding, top sealing, liquid injection, preliminary chemical formation, air bleeding, chemical formation, and molding in a drying room, the laminated battery core was assembled and used for measurement.

[0107] (2) Measurement of initial gram capacity of stacked battery: The stacked batteries thus fabricated were each allowed to stand for 5 minutes in a constant temperature environment of 25°C, discharged to 2.5V at 1 / 3C, allowed to stand for 5 minutes, and then charged to 4.3V or 4.25V at a constant current and voltage of 1 / 3C (Ni content >70%, upper limit voltage 4.25V). They were then charged at a constant voltage of 4.3V or 4.25V until the current reached ≦0.05mA and allowed to stand for 5 minutes. The charge capacity at this time was designated as C0. They were then discharged to 2.5V at 1 / 3C0. The discharge capacity at this time was the initial discharge capacity and designated as D0.

[0108] Dividing the measured discharge capacity value (ie, initial discharge capacity D0) by the mass of the positive electrode active material of the secondary battery gives the gram capacity of the positive electrode active material.

[0109] (3) Cycle performance measurement of secondary batteries at 25°C: Each secondary battery manufactured as described above was charged at 0.5C from 2.5 to 4.3V or 4.25V in a constant temperature environment of 25°C, up to 4.3V or 4.25V, and then charged at a constant voltage of 4.3V or 4.25V until the current reached ≦0.05mA. The battery was then left to stand for 5 minutes, and then discharged at 0.5C to 2.5V. The capacity was recorded as Dn (n=1, 2, 3...). The above procedure was repeated for more than 5,000 cycles, and the capacity fading value was measured. The capacity fading was determined as the degree of fading of the battery core (State of Health SOH) according to the ratio of Dn / D3. The number of cycles for each battery core when it had faded to 80% SOH was compared, and this was used as an evaluation index for cycle performance.

[0110] (4) Storage performance At a constant temperature of 60°C, the battery was charged from 2.5 V to 4.25–4.3 V at 0.5 C, then charged at a constant voltage of 4.25–4.4 V until the current reached ≤0.05 mA, and discharged to 2.5 V at 0.5 C. The discharge capacity was designated D0. The battery was then charged at a constant voltage of 4.25–4.4 V until the current reached ≤0.05 mA. The battery was then left to rest for 480 days. During the resting period, three consecutive cycles were performed every 10 days. Each cycle consisted of discharging to 2.5 V at 0.5 C, then charging at a constant voltage of 4.25–4.4 V until the current reached ≤0.05 mA. The discharge capacity of the third cycle was designated Dn (n = 1, 2, 3, ...), where n represents the nth 10-day resting period. The value obtained by dividing Dn by D0 was taken as the degree of decay of the battery core during the n-th 10-day high-temperature storage, and the number of days of high-temperature storage when the battery core had decayed to 80% was recorded.

[0111] (5) Charging performance test: First, measure the capacity of the pouch-type laminated battery. The procedure is as follows. Charge at a constant current of 0.33C until the full charge voltage V1, then switch to constant voltage charging. End the constant voltage charging when the charging current drops to 0.05C. Then, discharge at 0.33C until the full discharge voltage V2. Repeat this process three times. Based on the capacity result of the third time, the gram capacity of the positive electrode can be calculated using the result of the third time simultaneously.

[0112] Perform charge measurements on the pouch-type laminated battery at different rates (C1 < C2 < C3 < C4 < ··· < Cn). It is necessary to increase the charging rate from small to large during the measurement. During the charging process, it is necessary to simultaneously monitor the total voltage of the pouch-type laminated battery and the negative electrode voltage of the pouch-type laminated battery. The detailed process is as follows. The pouch-type laminated battery is charged at C1 until the full charge voltage V1 or the negative electrode voltage reaches 0V, extract the battery SOC value at the end of charging, and then discharge at 0.33C until the full discharge voltage V2. By repeating the above process, the SOC values at the end of charging at different rates can be obtained. Among them, Cn when charged at 100% SOC is the charging performance of the battery core of this solution.

[0113] Recorded the test results in Table 3.

[0114] Table 3

Table 3

[0115] As can be seen from the comparison of the data of Examples 1 to 4, whether the proportion of the phosphate-based positive electrode material is too high or too low, it will cause deterioration of the storage life. At the same time, when the proportion of the phosphate-based positive electrode material increases, the cycle life can be extended, but the charging performance will be deteriorated. As can be seen from the comparison of Examples 5 to 8 and 14 to 16, the increase of D V in 50 deteriorates the charging performance, but can improve the cycle and storage performance. However, D VIf the BET specific surface area is too large, it also affects performance. As can be seen from a comparison of Examples 9 to 12, the BET specific surface area of ​​the phosphate-based positive electrode material is too small, which deteriorates cycle and charge performance. As can be seen from a comparison of the data of Examples 18 to 21, if the BET specific surface area of ​​the ternary positive electrode material is too small, it deteriorates charge performance, cycle, and storage performance. As can be seen from a comparison of the data of Examples 22 to 29, if the Ni content is too high, the gram capacity increases but the charge performance, cycle, and storage performance deteriorate, and if the Co content is too high, the charge performance and storage performance improve but the gram capacity and cycle performance deteriorate.

[0116] Although the present application has been described with reference to preferred embodiments, various modifications may be made and some equivalents may be substituted without departing from the scope of the present application. In particular, the technical features described in each embodiment may be combined in any manner unless structurally inconsistent. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims. [Explanation of symbols]

[0117] 1 battery pack 2 Upper case 3 Lower case 4 Battery Module 5 Secondary battery 51 Casing 52 Electrode Assembly 53 Top cover assembly

Claims

1. A cathode material composition comprising a phosphate-based cathode material and a ternary cathode material, wherein a weight of the phosphate-based cathode material is designated W1, a weight of the ternary cathode material is designated W2, α=W1 / (W1+W2), and 3%≦α≦50%, the phosphate-based cathode material is a single crystal material or has a single crystal core, and the ternary cathode material is a single crystal or has a single crystal core. Positive electrode material composition.

2. The particle size distribution of the positive electrode material composition satisfies the relational expression 8>Aα+B(1-α)>1, where A is the D Ｖ 50, and B is the D of the ternary positive electrode material Ｖ It is 50. The positive electrode material composition according to claim 1 .

3. D of the phosphate-based positive electrode material Ｖ 50 is 0.8 to 8 μm, and D Ｖ 90<30 μm; The positive electrode material composition according to claim 1 .

4. The BET specific surface area of ​​the phosphate-based positive electrode material is 8 to 20 m ２ / g, The positive electrode material composition according to claim 1 .

5. The chemical formula of the phosphate-based positive electrode material is Li １+ｘ Mn １－ｙ A ｙ P １－ｚ R ｚ O ４ wherein x is any number within the range of -0.100 to 0.100, y is any number within the range of 0.001 to 0.500, and z is any number within the range of 0.001 to 0.100, and the values ​​of x, y, and z satisfy the following condition, i.e., to keep the chemical formula electrically neutral; A comprises one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and optionally A comprises one or more elements selected from the group consisting of Fe, Ti, V, Ni, Co, and Mg; R comprises one or more elements selected from the group consisting of B, Si, N, S, F, Cl, and Br, and optionally R comprises one or more elements selected from the group consisting of B, Si, N, and S; Alternatively, the chemical formula of the phosphate-based positive electrode material is Li ａ A ｘ Mn １－ｙ B ｙ P １－z C z O ４－ｎ D ｎ wherein A includes one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from the group consisting of B (boron), S, Si, and N; and D includes one or more elements selected from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1; x is selected from the range of 0.001 to 0.1; y is selected from the range of 0.001 to 0.5; z is selected from the range of 0.001 to 0.1; and n is selected from the range of 0.001 to 0.1; and the phosphate-based positive electrode material is electrically neutral. The positive electrode material composition according to claim 1 .

6. The phosphate-based positive electrode material includes a single crystal core and a coating layer that coats the single crystal core, and the single crystal core has the chemical formula Li １+ｘ Mn １－ｙ A ｙ P １－z R z O ４ or the chemical formula Li ａ A ｘ Mn １－ｙ B ｙ P １－z C z O ４－ｎ D ｎ wherein the coating layer is optionally one or more layers of pyrophosphate, phosphate, or carbon; The positive electrode material composition according to claim 5 .

7. D of the ternary positive electrode material Ｖ 50 is 2 to 8 μm, and D Ｖ 99≦18 μm, The positive electrode material composition according to claim 1 .

8. The BET specific surface area of ​​the ternary positive electrode material is 0.42 to 1.5 m ２ / g, The positive electrode material composition according to claim 1 .

9. The ternary positive electrode material is a single-crystal NCM ternary positive electrode material or a single-crystal NCA ternary positive electrode material, and optionally, the Ni molar content in the ternary positive electrode material is 50% to 99.5% and the Co molar content is 0.5% to 49.5%, and more optionally, the Ni molar content is 60% to 88% and the Co molar content is 5% to 35%; The positive electrode material composition according to claim 1 .

10. The ternary positive electrode material has the chemical formula Li ａ’ Ni ｂ’ Co ｃ’ M1 ｄ’ M2 ｅ’ O ｆ’ R' ｇ’ wherein 0.75≦a′≦1.2, 0<b′<1, 0<c′<1, 0<d′<1, 0≦e′≦0.2, 1≦f′≦2.5, 0≦g′≦1, and f′+g′≦3; M1 is Mn element and / or Al element; M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb; and R′ is one or more elements selected from N, F, S, and Cl. The positive electrode material composition according to claim 9 .

11. A secondary battery comprising a positive electrode piece, the positive electrode piece comprising a positive electrode active material, the positive electrode active material being the positive electrode material composition according to any one of claims 1 to 10. Secondary battery.

12. An electrical device including a secondary battery, wherein the secondary battery is selected from the secondary batteries of claim 11. Electrical equipment.

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