A positive electrode material composition, a secondary battery, and an electric device

Abstract

The application provides a positive electrode material composition, a secondary battery and an electric device to improve the high-temperature storage performance of the battery. The positive electrode material composition comprises a phosphate positive electrode material and a ternary positive electrode material, the weight of the phosphate positive electrode material is denoted as W1, the weight of the ternary positive electrode material is denoted as W2, alpha = W1 / (W1+W2), 3% <= alpha <= 50%, the phosphate positive electrode material is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core. The phosphate positive electrode material has strong phosphate polyanion material stability, good cycle stability, and a service life advantage; the ternary positive electrode material has a higher energy density. The phosphate positive electrode material is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core, further improving the cycle performance of the positive electrode material; and the single crystal has a small BET specific surface area, a stable structure, a large compaction density, and better high-temperature storage performance.

Description

[0001] This application is a divisional application of patent application 202380009727.3, filed on March 7, 2023, entitled "A positive electrode material composition, a secondary battery and an electric device". TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a positive electrode material composition, a secondary battery and an electric device. BACKGROUND

[0003] A lithium ion battery is a kind of secondary battery (rechargeable battery), which mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charging and discharging process, Li ions are embedded and de-embedded between the two electrodes: when charging, Li ions are de-embedded from the positive electrode, embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; when discharging, the opposite is true.

[0004] At present, there are many methods to improve the cycle performance of lithium ion batteries. The positive electrode material is doped or coated to modify, so as to slow down the deterioration of the crystal structure of the positive electrode material during the cycle process; or the positive electrode materials with different advantages are combined to take the advantages and make up for the disadvantages to improve the cycle performance and energy density of the battery. For example, lithium iron phosphate positive electrode material and ternary positive electrode material are combined, but usually the combination of the two is still dominated by ternary positive electrode material, which is limited by the cycle stability of ternary positive electrode material, and the cycle stability of the combination is not improved enough, especially the high-temperature storage performance is not good enough. SUMMARY

[0005] The present application provides a positive electrode material composition, a secondary battery and an electric device to improve the high-temperature storage performance of the battery.

[0006] According to a first aspect of the present application, a positive electrode material composition is provided, comprising a phosphate-based positive electrode material and a ternary positive electrode material, the weight of the phosphate-based positive electrode material is denoted as W1, the weight of the ternary positive electrode material is denoted as W2, α = W1 / (W1+W2), 3%≤α≤50%, the phosphate-based positive electrode material is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core.

[0007] Although the phosphate positive electrode material has low energy density, the material structure has strong phosphate polyanion material stability, good cycle stability, and life advantage; the ternary positive electrode material has high energy density, but the layered transition metal oxide faces material loss such as phase change / Li-Ni mixed arrangement / oxygen release and structure collapse in the cycle process, resulting in poor life of the ternary positive electrode material compared with the phosphate positive electrode material. The phosphate positive electrode material in the application is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core, further improving the cycle performance of the positive electrode material; and the BET specific surface area of the single crystal is small, the structure is stable, the compaction density is large, and the high-temperature storage performance is better.

[0008] In any implementation form of the first aspect, the particle size distribution of the positive electrode material composition satisfies the following relationship: 8 > Aa + B (1-a) > 1, wherein A is the D V 50 of the phosphate positive electrode material, and B is the D V 50 of the ternary positive electrode material. Further improve the particle size matching effect between the phosphate positive electrode material and the ternary positive electrode material, thereby significantly improving the high-temperature storage performance.

[0009] In any implementation form of the first aspect, the D V 50 of the phosphate positive electrode material is 0.8-8 μm, and the D 90 V50 is less than 30 μm, so as to improve the processing feasibility and high-temperature stability of the positive electrode material composition.

[0010] In the first implementation form of the first aspect, the BET specific surface area of the phosphate positive electrode material is 8-20 m 2 / g, which can further improve the structure stability, compaction density and high-temperature storage performance of the positive electrode material composition.

[0011] In the first implementation form of the first aspect, the chemical formula of the phosphate positive electrode material is Li 1+x Mn 1- y A y P 1-z R zO4, wherein x is any number in the range of -0.100-0.100, y is any number in the range of 0.001-0.500, and z is any number in the range of 0.001-0.100, the values of x, y, and z satisfy the following condition: the chemical formula is electrically neutral; A includes one or more elements 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 from the group consisting of Fe, Ti, V, Ni, Co, and Mg; and R includes one or more elements from the group consisting of B, Si, N, S, F, Cl, and Br, and optionally R includes one element from the group consisting of B, Si, N, and S. Doping the phosphate-based positive electrode material with elements A and R in the phosphate-based material helps improve the structural stability of the phosphate-based positive electrode material and the rate capability of a secondary battery having the same.

[0012] In a second embodiment of the first aspect, the phosphate-based positive electrode material has a chemical formula of 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 from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W, B includes one or more elements from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge, C includes one or more elements from the group consisting of B (boron), S, Si, and N, D includes one or more elements 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, 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 above-described specific elements in the above-described four positions in specific amounts, the rate capability, cycle performance, and / or high-temperature stability of the phosphate-based positive electrode material can be significantly improved.

[0013] In any embodiment of the first aspect, the phosphate-based positive electrode material optionally includes a single-crystal core, and a coating layer that coats the single-crystal core, the single-crystal core having a chemical formula of Li 1+x Mn 1-y A y P 1-z R z O4, or a chemical formula of Li a A x Mn 1-y By P 1-z C z O 4-n D n The coating layer can optionally be one or more layers of pyrophosphate, phosphate, or carbon. These functional coating layers can effectively inhibit the dissolution of transition metals and reduce surface side reactions in phosphate-based cathode materials.

[0014] In any embodiment of the first aspect, the D of the above-mentioned ternary cathode material V 50 is 2-8 μm, and D V 99≤18μm. Particle size affects the specific capacity after mixing and controls the D of ternary cathode materials. V 50 and D V 99 helps to shorten the lithium-ion diffusion path and bulk diffusion resistance, reduce material polarization, and has a more significant effect on improving capacity after mixing.

[0015] In any embodiment of the first aspect, the BET specific surface area of ​​the ternary cathode material is 0.42–1.5 m². 2 / g. This can further improve the structural stability, compaction density, and high-temperature storage performance of the cathode material.

[0016] In any embodiment of the first aspect, the aforementioned ternary cathode material is a single-crystal NCM ternary cathode material or a single-crystal NCA ternary cathode material. Optionally, the molar content of Ni in the ternary cathode material is 50% to 99.5%, and the molar content of Co is 0.5% to 49.5%. Further, 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 capacity utilization of the ternary cathode material and has a significant impact on the improvement of the energy density of the blended material. The molar content of Co increases the electronic conductivity and ionic conductivity of the system, which can effectively improve the charging capability of the ternary cathode material.

[0017] In any embodiment 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. Element doping is used to improve the cycle performance and rate performance of the ternary cathode material.

[0018] According to the second aspect of the present application, a secondary battery is provided. The secondary battery includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode active material, which is any one of the positive electrode material compositions in the first aspect above. The secondary battery with the positive electrode material composition of the present application effectively improves the high-temperature storage performance while having high energy density and cycle performance.

[0019] According to the third aspect of the present application, an electrical device is provided, including a secondary battery selected from the secondary batteries in the second aspect. The electrical device has better working stability at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on the drawings without creative efforts.

[0021] Figure 1 It is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0022] Figure 2 is Figure 1 The exploded view of the secondary battery according to an embodiment of the present application shown.

[0023] Figure 3 It is a schematic diagram of a battery module according to an embodiment of the present application.

[0024] Figure 4 It is a schematic diagram of a battery pack according to an embodiment of the present application.

[0025] Figure 5 is Figure 4 The exploded view of the battery pack according to an embodiment of the present application shown.

[0026] Figure 6 It is a schematic diagram of an electrical device using the secondary battery according to an embodiment of the present application as a power source.

[0027] The accompanying drawings are not drawn to scale.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0030] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0031] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the positive electrode material composition, secondary battery, and power supply device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0035] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0038] [Rechargeable Battery]

[0039] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after being discharged to activate the active materials and continue to be used.

[0040] Typically, a secondary battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through. The electrolyte, also positioned between the positive and negative electrodes, mainly serves to conduct active ions.

[0041] [Cathode Material]

[0042] One embodiment of this application provides a cathode material composition, including a phosphate cathode material and a ternary cathode material. The weight of the phosphate cathode material is denoted as W1, the weight of the ternary cathode material is denoted as W2, α = W1 / (W1+W2), 3% ≤ α ≤ 50%, the phosphate 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.

[0043] Although phosphate-based cathode materials have low energy density, their structure provides strong stability and good cycle stability, resulting in a longer lifespan. Ternary cathode materials, while having higher energy density, suffer from material losses during cycling due to phase transitions, Li-Ni mixing, oxygen release, and structural collapse in their layered transition metal oxides, leading to a shorter lifespan compared to phosphate-based materials. This application addresses this by using single-crystal phosphate-based cathode materials or materials with single-crystal cores, as well as single-crystal ternary cathode materials, further improving cycle performance. Moreover, single-crystal materials have a smaller BET specific surface area, greater structural stability, higher compaction density, and better high-temperature storage performance.

[0044] As α increases within the aforementioned range, the cycling capability of the cathode material composition is enhanced.

[0045] Terminology Explanation:

[0046] Phosphate-based cathode materials: These include not only LiMnPO4, but also lithium manganese iron phosphate (LiMnPO4). x Fe 1-x Cathode materials of the PO4 series, lithium manganese aluminum phosphate (LiMn) x Al 1-x Positron emission tomography (PO4) series cathode materials, such as LiMn x Fe 1-x PO4, doped LiMn x Fe 1-x PO4, LiMn with coating x Fe 1-x PO4.

[0047] Polycrystalline: refers to cathode materials existing in the form of aggregates;

[0048] Single crystal: There is no primary particle agglomeration. Its particle size is generally 10-50 times larger than that of primary particles in agglomerated materials (polycrystalline). It has high internal crystallinity and no excess pores.

[0049] When the positive electrode material composition exists in the positive electrode sheet, the positive electrode sheet is cut by argon ion polishing, and the cut surface is analyzed for elements. Then, the main element ratios of phosphate-based positive electrode materials and ternary materials are compared, and the weight is determined according to the ratio.

[0050] In some embodiments, the particle size distribution of the above-mentioned cathode material composition satisfies the following relationship: 8>Aα+B(1-α)>1, where A is the DV of the phosphate-based cathode material. 50 B represents the DV of the ternary cathode material. 50 This further improves the particle size distribution between phosphate-based cathode materials and ternary cathode materials, thereby significantly enhancing high-temperature storage performance.

[0051] In some embodiments, the D of the above-mentioned phosphate cathode material V 50 is 0.8–8 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, to improve the processing feasibility and high-temperature stability of the cathode material composition.

[0052] In some embodiments, the BET specific surface area of ​​the above-mentioned phosphate-based cathode material is 8–20 m². 2 / g, for example, 8m 2 / g, 10m 2 / g、12m 2 / g, 15m 2 / g or 20m 2 / g can further improve the structural stability, compaction density and high-temperature storage performance of the cathode material composition.

[0053] In some embodiments, the chemical formula of the above-mentioned phosphate-based cathode material is Li 1+x Mn 1-y A y P 1-z R zIn the chemical formula O4, x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, and z is any value in the range of 0.001 to 0.100. The values ​​of x, y, and z satisfy the following condition: maintaining the electrical neutrality of the chemical formula; 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 may be selected from 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 an element selected from the group consisting of B, Si, N, and S. The addition of element A at the manganese sites of lithium manganese iron phosphate helps to reduce the lattice change rate of lithium manganese iron phosphate during lithium insertion / extraction, improves the structural stability of the lithium manganese iron phosphate cathode material, greatly reduces manganese dissolution, and lowers the oxygen activity on the particle surface. The addition of element R at the phosphorus site helps to change the ease with which the Mn-O bond length changes, thereby lowering the lithium-ion migration barrier, promoting lithium-ion migration, and improving the rate performance of the secondary battery.

[0054] In some embodiments, the chemical formula of the above-mentioned phosphate-based cathode 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 from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements from the group consisting of B (boron), S, Si, and N; D includes one or more elements from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, 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, and 1.01; and x is selected from 0.001 to 0.1. The range of y is selected from 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 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, 0.34, 0.345, 0.349, 0.35, 0.4, 0.5, z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, 0.1, and the phosphate-based cathode material is electrically neutral. A, B, C, and D are the elements doped at the Li, Mn, P, and O sites of the compound LiMnPO4, respectively. Not wanting to be confined to theory, it is now believed that the performance improvement of phosphates is related to reducing the lattice change rate and decreasing surface activity during lithium insertion / extraction. Reducing the lattice change rate can decrease the difference in lattice constants between the two phases at the grain boundary, reduce interfacial stress, and enhance Li... +The transport capacity at the interface enhances the rate performance of the positive electrode active material. However, high surface activity easily leads to severe interfacial side reactions, exacerbating gas generation, electrolyte consumption, and interface damage, thus affecting the battery's cycle performance. The aforementioned phosphate-based positive electrode materials reduce the lattice change rate through Li and Mn site doping. Mn site doping also effectively reduces surface activity, thereby suppressing Mn dissolution and interfacial side reactions between the positive electrode active material and the electrolyte. P-site doping accelerates the change rate of the Mn-O bond length, lowering the small polaron migration barrier and thus improving electronic conductivity. O-site doping has a good effect on reducing interfacial side reactions. P-site and O-site doping also affects the Mn dissolution and kinetic properties of antisite defects. Therefore, doping reduces the concentration of antisite defects in the material, improves the kinetic properties and specific capacity, and can also change the particle morphology, thereby increasing the compaction density. The applicant unexpectedly discovered that by simultaneously doping specific elements at specific amounts at the Li, Mn, P, and O sites of the compound LiMnPO4, it is possible to obtain significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site dopants, resulting in significantly improved cycle performance and / or high-temperature stability, and also improving the specific capacity and compaction density of the material.

[0055] In some embodiments, the phosphate-based cathode material may optionally include a single-crystal core and a functional coating layer covering the single-crystal core, wherein the single-crystal core has the chemical formula Li. 1+x Mn 1-y A y P 1-z R z O4, the functional coating layer can optionally be one or more layers of pyrophosphate, phosphate, or carbon. Due to the high migration barrier (>1 eV) of transition metals in pyrophosphate, the dissolution of transition metals can be effectively suppressed. Phosphate has excellent lithium-ion conduction ability and can reduce surface lithium content. The carbon layer can effectively improve 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 the corrosion of the active material by the electrolyte; at the same time, the aforementioned carbon layer in the mixture can also optimize the conductive network around the ternary cathode material, improving the mixing uniformity of phosphate-based cathode materials and ternary cathode materials.

[0056] In some embodiments, the D of the above-mentioned ternary cathode material V 50 is 2-8 μm, and D V 99≤18μm. Particle size affects the specific capacity after mixing and controls the D of ternary cathode materials. V 50 and D V 99 helps to shorten the lithium-ion diffusion path and bulk diffusion resistance, reduce material polarization, and has a more significant effect on improving capacity after mixing.

[0057] In some embodiments, the BET specific surface area of the above ternary cathode material is 0.42 - 1.5 m 2 / g. It can further improve the structural stability, tap density and high-temperature storage performance of the cathode material composition.

[0058] In some embodiments, the above ternary cathode material is a single-crystal NCM ternary cathode material or a single-crystal NCA ternary cathode material. Optionally, the molar content of Ni in the ternary cathode material is 50% - 99.5%, such as 50%, 55%, 60%, 70%, 80%, 88%, 90%, 95% or 99.5%, and the molar content of Co is 0.5% - 49.5%, such as 0.5%, 5%, 10%, 20%, 30%, 35%, 40%, 45% or 50%; Further optionally, the molar content of Ni is 60% - 88%, and the molar content of Co is 5% - 35%. The molar content of Ni affects the capacity performance of the ternary cathode material and has a great impact on improving the energy density of the blended material. The increase in the molar content of Co can improve the electronic conductivity and ionic conductivity of the system, and can effectively improve the charging ability of the ternary cathode material.

[0059] In some embodiments, the above 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. Element doping is used to improve the cycle performance and rate performance of the ternary cathode material.

[0060] Both the above phosphate cathode material and ternary cathode material of the present application can be commercial materials or can be prepared, such as a series of single-crystal lithium iron manganese phosphate cathode materials produced by Shenzhen Defang Nano-tech Co., Ltd. (abbreviated as Defang Nano in the examples); a series of single-crystal ternary cathode materials produced by Ningbo Ronbay New Energy Technology Co., Ltd. (abbreviated as Ronbay in the examples).

[0061] [Positive electrode sheet]

[0062] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0063] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0064] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0065] In some embodiments, the positive electrode active material is any of the positive electrode material compositions provided in this application.

[0066] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0067] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0068] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0069] [Negative electrode plate]

[0070] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0071] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0072] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0073] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0074] In some embodiments, the negative electrode film layer may optionally include a binder. As an example, the binder 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).

[0075] In some embodiments, the negative electrode film may optionally include a conductive agent. As an 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.

[0076] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0077] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0078] [Electrolytes]

[0079] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0080] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0081] In some embodiments, the electrolyte salt may 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0082] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0083] In some embodiments, the electrolyte may optionally include additives. As examples, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0084] [Isolation membrane]

[0085] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0086] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0087] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0088] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0089] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0090] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured secondary battery 5.

[0091] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0092] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0093] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0094] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0095] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0096] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0097] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, 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 and satellites, energy storage systems, etc.

[0098] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0099] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0100] [Example]

[0101] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0102] The source of cathode materials, including phosphate-based cathode materials such as LiMn 0.6 Fe 0.4 PO4 was purchased from Defang Nano, ternary cathode material was purchased from Rongbai Technology, and the remaining cathode materials were prepared using the following methods.

[0103] Preparation Example 1: Li 0.999 Mn 0.60 Fe 0.393 V 0.004 Co 0.003 P 0.999 S 0.001 Preparation of O4

[0104] (1) Preparation of co-doped lithium manganese iron phosphate core

[0105] Preparation of Fe, Co, and V co-doped manganese oxalate: 689.5 g of manganese carbonate (calculated as MnCO3), 455.2 g of ferrous carbonate (calculated as FeCO3), 4.6 g of cobalt sulfate (calculated as CoSO4), and 4.9 g of vanadium dichloride (calculated as VCl2) were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reaction vessel, and 5 liters of deionized water and 1260.6 g of oxalic acid dihydrate (calculated as C2H2O4·2H2O) were added. The reaction vessel was heated to 80°C and stirred at 600 rpm for 6 hours until the reaction was terminated (no bubbles were generated), yielding a suspension of Fe, Co, V, and S co-doped manganese oxalate. The suspension was then filtered, and the filter cake was dried at 120°C. The cake was then ground using an air mill, graded, and passed through a 325-mesh sieve to obtain Fe, Co, and V co-doped manganese oxalate dihydrate particles.

[0106] Preparation of Fe, Co, V, and S co-doped lithium manganese iron phosphate: 1793.4 g of manganese oxalate dihydrate particles obtained in the previous step, 369.0 g of lithium carbonate (calculated as Li₂CO₃), 1.6 g of 60% dilute sulfuric acid (calculated as 60% H₂SO₄), and 1148.9 g of ammonium dihydrogen phosphate (calculated as NH₄H₂PO₄) were added to 20 L of deionized water. The mixture was stirred for 10 hours to ensure homogeneity, resulting in a slurry. The slurry was transferred to a spray dryer for spray drying and granulation. The drying temperature was set at 250 °C, and the drying time was 4 hours to obtain powder. Under a nitrogen (90 vol%) + hydrogen (10 vol%) protective atmosphere, the powder was sintered at 700 °C for 4 hours to obtain 1572.1 g of Fe, Co, V, and S co-doped lithium manganese iron phosphate.

[0107] Preparation 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 Preparation

[0108] 1) Preparation of positive electrode active materials

[0109] Preparation of Fe-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 reaction vessel, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction vessel was heated to 80 °C and stirred at 600 rpm for 6 hours until the reaction was terminated (no more bubbles were generated), yielding a Fe-doped manganese oxalate suspension. The suspension was then filtered, and the filter cake was dried at 120 °C. Afterward, the filter cake was ground, classified, and passed through a 325-mesh sieve. The desired particle size was then achieved, yielding Fe-doped manganese oxalate particles.

[0110] Preparation of doped lithium manganese iron phosphate: 1 mol of the above-mentioned manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO4)3, an 85% phosphoric acid aqueous solution 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 equipment for spray drying and granulation. The drying temperature was set at 250℃, and the granules were dried for 4 hours to obtain particles. Under a protective atmosphere of nitrogen (90 vol%) + hydrogen (10 vol%), the above powder was sintered at 700℃ for 10 hours to obtain 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 .

[0111] The volume particle size distribution and specific surface area of ​​the materials obtained by adjusting the reactor heating temperature, sieve mesh size and sintering temperature of Preparation Examples 1 and 2 are adjusted. The preparation process of each material will not be described in detail in this application.

[0112] The appearance of the cathode material was observed by scanning electron microscopy to determine that the lithium manganese iron phosphate cathode material and ternary cathode material in each embodiment were single crystal particles (a single crystal particle is a complete crystal sphere, while polycrystalline is a large sphere formed by the aggregation of multiple small primary particles).

[0113] The particle size of the lithium manganese iron phosphate cathode material and the ternary cathode material in each embodiment was determined by powder laser particle size analysis: referring to the national standard GB / T19077-2016, deionized water was used as the solvent, and the material was sonicated for 5 minutes before testing.

[0114] Powder specific surface area (BET) test: The test is conducted in accordance with GB / T 19587-2004. Before the test, the powder is dried in a vacuum oven at 200℃ for ≥2h. The required amount of powder is >20g.

[0115] Primary particle size test of powder: The primary particle size was confirmed by SEM testing of the powder.

[0116] Specific capacity test: The prepared coin cells were placed in a constant temperature environment of 25℃ for 5 minutes, discharged at 0.1C to 2.5V, and then placed in a constant voltage environment at 0.1C to 4.3V or 4.25V (Ni content > 70%, upper limit voltage is 4.25V). Then, they were charged at 4.3V or 4.25V with constant voltage until the current ≤ 0.05mA and placed in a constant voltage environment for 5 minutes. The charging capacity at this time is recorded as C0. Then, they were discharged at 0.1C to 2.5V. The discharge capacity at this time is the initial discharge capacity and is recorded as D0.

[0117] Dividing the tested discharge capacity value (i.e., the initial discharge capacity D0) by the mass of the positive electrode active material in the coin cell gives the specific capacity of the positive electrode active material.

[0118] The specific capacity and D of the lithium iron phosphate cathode material and ternary cathode material used in the examples V 50. D V 90. The specific surface area of ​​BET is recorded in Table 1.

[0119] Table 1

[0120]

[0121]

[0122] Among them, NCM-18 is a secondary particle, while the rest are single crystal particles.

[0123] The composition of the cathode material compositions of each embodiment and comparative example is shown in Table 2 (where the ratio of LMFP is the mass ratio of LMFP and NCM).

[0124] Table 2

[0125]

[0126]

[0127]

[0128] The electrical performance was tested using the following methods.

[0129] (1) Fabrication of hybrid electrode stacked cells:

[0130] Preparation of mixed positive electrode: The positive electrode active composition in the above examples and comparative examples is used as the positive electrode active material (the mixing ratio is based on the mass ratio of the two, mA+mB=100%), polyvinylidene fluoride (PVDF), and conductive carbon are added to a certain amount of N-methylpyrrolidone (NMP). The mass ratio of active material:PVDF:conductive carbon is 90:5:5. The mixture is stirred in a drying room to form a uniform slurry with the viscosity controlled at 3000~10000mPa·S. The slurry is coated on aluminum foil and then dried and cold-pressed to form a positive electrode sheet.

[0131] Graphite anode preparation: Artificial graphite is used as the anode active material. The mass ratio of sodium carboxymethyl cellulose (CMC), conductive carbon, and styrene-butadiene rubber (SBR) is 94:1.5:2:2.5. A certain amount of deionized water is added, and the mixture is stirred in a drying room to form a uniform slurry with a viscosity controlled at 2000-12000 mPa·s. The slurry is then coated onto copper foil. The anode coating mass is referenced to the matching relationship with the cathode (94% * anode coating mass * graphite specific capacity = 1.15 * 90% * cathode coating mass * mixed cathode specific capacity, where the specific capacity is referenced to the specific capacity information of the material for the third cycle of the lithium half-cell powder). After drying and cold pressing, the anode sheet is formed.

[0132] 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);

[0133] A porous polymer film made of polyethylene (PE) is used as a separator.

[0134] In a drying room, the cells are assembled into stacked cells for testing through processes such as electrode cutting, cleaning of tabs, stacking, welding, top sealing, liquid injection, pre-formation, degassing, formation, and molding.

[0135] (2) Initial specific capacity test of stacked cells:

[0136] The stacked cells prepared above were placed in a constant temperature environment of 25°C for 5 minutes, discharged at 1 / 3C to 2.5V, and then charged at 1 / 3C with constant current and constant voltage to 4.3V or 4.25V (Ni content > 70%, upper limit voltage is 4.25V). Then, they were charged at 4.3V or 4.25V with constant voltage until the current ≤ 0.05mA and placed in a constant temperature environment for 5 minutes. The charging capacity at this time is recorded as C0. Then, the cells were discharged at 1 / 3C0 to 2.5V. The discharge capacity at this time is the initial discharge capacity, recorded as D0.

[0137] Dividing the tested discharge capacity value (i.e., the initial discharge capacity D0) by the mass of the positive electrode active material in the secondary battery gives the total initial specific capacity of the positive electrode active material.

[0138] (3) Cyclic performance test of secondary battery at 25℃:

[0139] Each of the secondary batteries prepared above was charged at 0.5C0 to 4.3V or 4.25V under a constant temperature environment of 25℃ and at 2.5~4.3V or 4.25V. Then, it was charged at a constant voltage of 4.3V or 4.25V until the current ≤0.05mA, and allowed to stand for 5 minutes. Then, it was discharged at 0.5C to 2.5V. The capacity was recorded as Dn (n=1,2,3……). The above operation was repeated for >5000 cycles. The capacity decay value was measured. The capacity decay was used as the cell decay degree (State of health SOH) according to the ratio of Dn / D3. The number of cycles of each cell when decayed to 80% SOH was compared as the evaluation index of cycle capability.

[0140] (4) Storage capacity

[0141] In a constant temperature environment of 60℃, the battery was charged at 0.5C from 2.5V to 4.25-4.3V, then charged at a constant voltage of 4.25-4.4V until the current ≤0.05mA, and discharged at 0.5C to 2.5V. The discharge capacity D0 was recorded. Then, the battery was charged at a constant voltage of 4.25-4.4V until the current ≤0.05mA. The battery was then left to stand for 480 days. During the standing period, three cycles were performed every 10 days. In each cycle, the battery was first discharged at 0.5C to 2.5V and then charged at a constant voltage of 4.25-4.4V until the current ≤0.05mA. The discharge capacity of the third cycle was recorded as Dn (n=1,2,3……), where n represents the nth 10-day standing period. The value of Dn divided by D0 was used as the degree of cell degradation after the nth 10-day high-temperature storage. The number of days the cell degradation reached 80% was recorded.

[0142] (5) Charging capacity experiment:

[0143] First, the capacity of the pouch-type laminated battery is tested. The procedure is as follows: constant current charging at 0.33C to the full charge voltage V1, then constant voltage charging. When the charging current decreases to 0.05C, the constant voltage charging ends. Then, discharge at 0.33C to the full discharge voltage V2. This procedure is repeated 3 times, and the capacity result of the 3rd test is taken as the standard. The specific capacity of the positive electrode can also be calculated using the 3rd result.

[0144] The soft-pack laminated battery is tested for charging at different rates (C1 < C2 < C3 < C4 < …… < Cn). During the test, the charging rate should increase from small to large, and the full-cell voltage and the negative electrode voltage of the soft-pack laminated battery should be monitored simultaneously during the charging process. The detailed process is as follows: The soft-pack laminated battery is charged at C1 to the full-charge voltage V1 or the negative electrode voltage reaches 0V, and the SOC value of the battery at the end of charging is extracted. Then, it is discharged at 0.33C to the full-discharge voltage V2. Repeating the above process can obtain the SOC values at the end of charging at different rates. Here, Cn at 100% SOC charging is the charging capacity of the battery cells in this solution.

[0145] The test results are recorded in Table 3.

[0146] Table 3

[0147]

[0148]

[0149] From the data comparison of Examples 1-4, it can be seen that too high or too low proportion of phosphate-based cathode materials will cause deterioration of the storage life. At the same time, increasing the proportion of phosphate-based cathode materials can increase the cycle life but will deteriorate the charging capacity. From the comparison of Examples 5 to 8 and 14 to 16, it can be seen that the increase of D V 50 will deteriorate the charging capacity, but it can improve the cycle and storage. However, too large D V 50 will also affect the performance. From the comparison of Examples 9 to 12, it can be seen that too small BET of the phosphate-based cathode material will deteriorate the cycle and charging capacity. From the data comparison of Examples 18 to 21, it can be seen that too small BET of the ternary cathode material will deteriorate the charging capacity, cycle and storage performance. From the data comparison of Examples 22 to 29, it can be seen that too much Ni content will increase the specific capacity, but will deteriorate the charging capacity, cycle and storage. Too much Co content will improve the charging capacity and storage, but will deteriorate the specific capacity and cycle performance.

[0150] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A positive electrode material composition, wherein, The positive electrode material includes a phosphate positive electrode material and a ternary positive electrode material, the weight of the phosphate positive electrode material is denoted as W1, the weight of the ternary positive electrode material is denoted as W2, α = W1 / (W1+W2), 3%≤α≤50%, the phosphate positive electrode material is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core. D of the phosphate-based positive electrode material is 0.8 μm to 8 μm, and D V 50 is 0.8 μm to 8 μm, and D V 90 is less than 30 μm; D of the ternary cathode material is 0.1-0.2 V 50 is 2-8 μm.

2. The cathode material composition of claim 1, wherein, The particle size distribution of the positive electrode material composition satisfies the following relationship: 8 > Aa + B(l-a) > 1, wherein A is the D50 of the phosphate-based positive electrode material V 50, and B is the D50 of the ternary positive electrode material V 50.

3. The positive electrode material composition according to claim 1 or 2, wherein, D of the phosphate-based positive electrode material V 50 is 3 μm ~ 6 μm.

4. The positive electrode material composition according to claim 1 or 2, wherein, D of the phosphate-based positive electrode material V 50 is 4.0 μm to 4.4 μm.

5. The positive electrode material composition according to claim 1 or 2, wherein, D of the phosphate-based positive electrode material V 90 ≤ 18.3 μm.

6. The cathode material composition of any one of claims 1-2, wherein, The BET specific surface area of the phosphate-based positive electrode material is 8 m 2 / g ~ 20 m 2 / g.

7. The cathode material composition of claim 1, wherein, The phosphate-based cathode material has a chemical formula of Li 1+x Mn 1-y A y P 1-z R z O4, wherein x is any value within a range of -0.100-0.100, y is any value within a range of 0.001-0.500, and z is any value within a range of 0.001-0.100, the values of x, y, and z satisfying a condition such that the chemical formula remains electrically neutral; A includes one or more elements from a group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and R includes one or more elements from a group consisting of B, Si, N, S, F, Cl, and Br. Alternatively, the phosphate-based cathode material has a chemical formula of Li a A x Mn 1-y B y P 1-z C z O 4-n D n wherein the A comprises one or more elements from a group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W, the B comprises one or more elements from a group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge, the C comprises one or more elements from a group consisting of B, S, Si, and N, the D comprises one or more elements from a group consisting of S, F, Cl, and Br, the a is selected from a range of 0.9 to 1.1, the x is selected from a range of 0.001 to 0.1, the y is selected from a range of 0.001 to 0.5, the z is selected from a range of 0.001 to 0.1, the n is selected from a range of 0.001 to 0.1, and the phosphate-based cathode material is charge neutral.

8. The cathode material composition of claim 7, wherein, The phosphate-based cathode material has a chemical formula of Li 1+x Mn 1-y A y P 1-z R z O4, the A includes one or more elements from a group consisting of Fe, Ti, V, Ni, Co, and Mg.

9. The cathode material composition of claim 7, wherein, The R includes one element in a group consisting of B, Si, N, and S.

10. The cathode material composition of claim 7, wherein, The phosphate-based positive electrode material has a chemical formula of Li 1+x Mn 1-y A y P 1-z RzO4, wherein x is -0.001 or -0.006 in the chemical formula.

11. The cathode material composition of claim 7, wherein, The phosphate-based positive electrode material has a chemical formula of Li a A x Mn 1-y B y P 1-z C z O 4-n D n When a is 0.994-1.1 in the chemical formula, and / or; Y is 0.35-0.

5.

12. The cathode material composition of any one of claims 7-11, wherein, The phosphate-based cathode material comprises a single crystal inner core, a coating layer coating the single crystal inner core, the single crystal inner core has the chemical formula Li 1+x Mn 1-y A y P 1- z R z O4or the chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n .

13. The cathode material composition of claim 12, wherein, The coating layer is one or more layers of pyrophosphate, phosphate, or carbon.

14. The cathode material composition of any one of claims 1-2, wherein, D50 of the ternary positive electrode material is 2 μm to 6.5 μm, and D99 is 18 μm or less. V 50 is 2 μm to 6.5 μm, and D V 99 is 18 μm or less.

15. The cathode material composition of any one of claims 1-2, wherein, The BET specific surface area of the ternary cathode material is 0.42 m 2 / g ~ 1.5 m 2 / g.

16. The cathode material composition of any one of claims 1-2, wherein, The ternary positive electrode material is a single crystal NCM ternary positive electrode material or a single crystal NCA ternary positive electrode material.

17. The cathode material composition of claim 16, wherein, The mole content of Ni in the ternary positive electrode material is 50%-99.5%, and the mole content of Co is 0.5%-49.5%.

18. The cathode material composition of claim 17, wherein, The mole content of Ni in the ternary positive electrode material is 60%-88%, and the mole content of Co is 5%-35%.

19. The cathode material composition of any one of claims 1-2, wherein, The ternary cathode material has a 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, 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.

20. A secondary battery comprising a positive electrode sheet comprising a positive electrode active material, wherein, The positive electrode active material is the positive electrode material composition according to any one of claims 1-19.

21. An electrically powered device comprising a secondary battery, wherein The secondary battery is selected from the secondary batteries described in claim 20. The positive electrode material includes a phosphate positive electrode material and a ternary positive electrode material, the weight of the phosphate positive electrode material is denoted as W1, the weight of the ternary positive electrode material is denoted as W2, α = W1 / (W1+W2), 3%≤α≤50%, the phosphate positive electrode material is a single crystal material or has a single crystal core, and the ternary positive electrode material is a single crystal or has a single crystal core. The R includes one element in a group consisting of B, Si, N, and S. Y is 0.35-0.

5. The coating layer is one or more layers of pyrophosphate, phosphate, or carbon. The ternary positive electrode material is a single crystal NCM ternary positive electrode material or a single crystal NCA ternary positive electrode material. The mole content of Ni in the ternary positive electrode material is 50%-99.5%, and the mole content of Co is 0.5%-49.5%. The mole content of Ni in the ternary positive electrode material is 60%-88%, and the mole content of Co is 5%-35%. The positive electrode active material is the positive electrode material composition according to any one of claims 1-19. The secondary battery is selected from the secondary batteries described in claim 20.

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