WO2023245597A1 - 一种正极活性材料、二次电池、电池模块、电池包和用电装置 - Google Patents

一种正极活性材料、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2023245597A1
WO2023245597A1 PCT/CN2022/101030 CN2022101030W WO2023245597A1 WO 2023245597 A1 WO2023245597 A1 WO 2023245597A1 CN 2022101030 W CN2022101030 W CN 2022101030W WO 2023245597 A1 WO2023245597 A1 WO 2023245597A1
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active material
battery
positive electrode
average particle
cathode
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PCT/CN2022/101030
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English (en)
French (fr)
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林泽慧
倪欢
刘宏宇
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宁德时代新能源科技股份有限公司
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Priority to EP22929201.6A priority Critical patent/EP4318668A1/en
Priority to PCT/CN2022/101030 priority patent/WO2023245597A1/zh
Priority to KR1020237033411A priority patent/KR20240001313A/ko
Priority to CN202280061179.4A priority patent/CN118043998A/zh
Priority to US18/464,932 priority patent/US20230420671A1/en
Publication of WO2023245597A1 publication Critical patent/WO2023245597A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to a positive active material, a secondary battery, a battery module, a battery pack and an electrical device.
  • lithium-ion batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields. Due to the great development of lithium-ion batteries, higher requirements have been put forward for their energy density, cycle performance and safety performance. In addition, as the selection of cathode active materials becomes increasingly limited, high-nickel cathode active materials are considered to be the best choice to meet high energy density requirements.
  • This application was made in view of the above issues, and its purpose is to provide a positive electrode active material whose corresponding pole piece has a high compaction density, so that the corresponding battery has high energy density and safety while having good high-temperature cycle performance and high-temperature storage performance.
  • a first aspect of the present application provides a cathode active material comprising
  • Active material A its composition formula is
  • Active material B its composition formula is
  • Active material C its composition formula is
  • the average particle diameter Dv50 of the active material A is greater than the average particle diameter Dv50 of the active material B, and is greater than the average particle diameter Dv50 of the active material C.
  • the cathode active material of the present application contains active materials A, B and C with different average particle sizes and nickel contents, so that the compaction density of the corresponding electrode pieces is large, which makes the corresponding battery have high energy density and safety At the same time, it has good high temperature cycle performance and high temperature storage performance.
  • the average particle size Dv50 of active material A is 7-15 ⁇ m, optionally 8-14 ⁇ m; the Dv90 is 15-25 ⁇ m, optionally 18-22 ⁇ m; the average particle size Dv50 of active material B is 1-1 8 ⁇ m, optional 2-5 ⁇ m, Dv90 3-10 ⁇ m, optional 5-8 ⁇ m; the average particle size of active material C is 1-7 ⁇ m, optional 2-5 ⁇ m, Dv90 5-10 ⁇ m, optional 5 -8 ⁇ m. Therefore, by further defining the average particle size of each active material, the compaction density of the positive electrode sheet containing the positive active material is further increased, so that the corresponding battery has high energy density and safety while having good high-temperature cycling. performance and high-temperature storage performance.
  • the content ratio of the active material A, the active material B and the active material C is 1:0.5-8:0.1-10, optionally 1:0.8-6:0.2-8 , further options are 1:1.5-6:3-8. Therefore, through a specific proportion of each active material, the compaction density of the positive electrode sheet containing the positive electrode active material is further increased, which makes the corresponding battery have high energy density and safety while having good high-temperature cycle performance. and high temperature storage performance.
  • the sum of the content of the active material A and the active material B is equal to the content of the active material C, and each content is based on the total weight of the cathode active material.
  • the specific content of each active material further enables the positive electrode sheet containing the positive electrode active material to have a high compaction density, which enables the corresponding battery to have high energy density and safety while also having good high-temperature cycle performance. and high temperature storage performance.
  • the cathode active material has a specific surface area of 0.3-1.8 m 2 /g; and a compacted density of 3.0-3.6 g/cm 3 . Therefore, the cathode active material with a specific specific surface area and compacted density enables the corresponding battery to have high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • the active material A and/or the active material B and/or the active material C comprise M elements, where M is selected from Zr, Sr, B, Ti, Mg, Sn and Al. one or more. Therefore, by subjecting each active material to the above-mentioned treatment, the surface phase structure of the material can be stabilized, side reactions during the charge and discharge process can be suppressed, and the corresponding battery can further have high energy density, safety, and good high-temperature cycle performance. performance and high-temperature storage performance.
  • x1:x2:x3 is 1: (0.73-1.37): (0.73-1.37)
  • a1:a2:a3 is 1: (0.71-1.42): (0.31-1). Therefore, by limiting the proportion of lithium and nickel in each active material, the corresponding battery can further achieve high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • active material A is a polycrystalline material
  • active materials B and C are monocrystalline-like or single-crystalline materials.
  • the corresponding battery can further achieve high energy density and safety while also having good high-temperature cycle performance and high-temperature storage performance.
  • a second aspect of the application also provides a secondary battery, which is characterized by including the positive active material described in the first aspect of the application.
  • the resulting battery has high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • a third aspect of the present application provides a battery module including the secondary battery of the second aspect of the present application.
  • a fourth aspect of the application provides a battery pack, including the battery module of the third aspect of the application.
  • a fifth aspect of the present application provides an electrical device, including at least one selected from the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application. kind.
  • the positive active material of the present application contains active materials A, B and C with different average particle sizes and nickel contents, so that the compaction density of the positive electrode sheet containing the positive active material is large, thereby making the corresponding battery have high energy density. While being safe, it has good high-temperature cycle performance and high-temperature storage performance.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 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.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • 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).
  • high-nickel cathode active materials are mainly composed of secondary particles in the form of agglomeration and polycrystalline.
  • the high-nickel cathode active material As the Ni content increases, the gram capacity of the material also increases.
  • the high-nickel polycrystalline secondary particle material still has the following problems: 1) The stacking density is low, and the made electrode The compacted density of the sheets is low, which further reduces the specific energy of the battery; 2) the particles are easily broken, which increases the specific surface area of the material, which in turn leads to an increase in battery side reactions and severe battery gas production.
  • the positive active material of the first aspect of the application contains active materials A, B and C with different average particle sizes and nickel contents, so that the compaction density of the positive electrode sheet containing the positive active material is large, effectively solving the problem
  • the existing high-nickel cathode active materials have performance degradation problems such as particle fragmentation along grain boundaries, increase in specific surface area, destruction of electron/ion transmission paths, and electrolyte corrosion during cold pressing and circulation processes, which makes the corresponding battery have high performance. In addition to energy density and safety, it has good high-temperature cycle performance and high-temperature storage performance.
  • the present application proposes
  • a positive active material comprising
  • Active material A its composition formula is
  • Active material B its composition formula is
  • Active material C its composition formula is
  • the average particle diameter Dv50 of the active material A is greater than the average particle diameter Dv50 of the active material B, and is greater than the average particle diameter Dv50 of the active material C.
  • the positive active material of the present application contains active materials A, B and C with different average particle sizes and nickel contents, so that the compaction density of the positive electrode sheet containing the positive active material is high, and at the same time, it effectively solves the current problem.
  • the technical high-nickel cathode active materials have performance degradation problems such as particle fragmentation along grain boundaries, increase in specific surface area, destruction of electron/ion transmission paths, and electrolyte corrosion during cold pressing and circulation, which makes the corresponding battery with high energy In addition to density and safety, it has good high-temperature cycle performance and high-temperature storage performance.
  • the average particle size Dv50 of active material A is 7-15 ⁇ m, optionally 8-14 ⁇ m; the Dv90 is 15-25 ⁇ m, optionally 18-22 ⁇ m; the average particle size Dv50 of active material B is 1- 8 ⁇ m, optional 2-5 ⁇ m, Dv90 3-10 ⁇ m, optional 5-8 ⁇ m; the average particle size of active material C is 1-7 ⁇ m, optional 2-5 ⁇ m, Dv90 5-10 ⁇ m, optional 5 -8 ⁇ m.
  • the Dv10 of the active material A is 1-4 ⁇ m, preferably 2-3 ⁇ m; the Dv99 is 20-30 ⁇ m, preferably 24-28 ⁇ m.
  • the Dv10 of the active material B is 1-3 ⁇ m, preferably 1-2 ⁇ m; the Dv99 is 4-12 ⁇ m, preferably 6-10 ⁇ m.
  • the Dv10 of the active material C is 1-3 ⁇ m, preferably 1.5-2.5 ⁇ m; the Dv99 is 6-15 ⁇ m, preferably 7-13 ⁇ m.
  • the Dv10 is the corresponding particle size when the cumulative volume distribution percentage of the sample reaches 10%; Dv50 is the corresponding particle size when the cumulative volume distribution percentage of the sample reaches 50%, also known as the average particle size; Dv90 is the cumulative volume distribution of the sample. The corresponding particle size when the percentage reaches 90%; Dv99 is the corresponding particle size when the cumulative volume distribution percentage of the sample reaches 99%.
  • the average particle size Dv50 of the active material A is 11.5-12.5 ⁇ m
  • the average particle size Dv50 of the active material B is 3.8-4.2 ⁇ m
  • the average particle size Dv50 of the active material C is 3.8-4.2 ⁇ m.
  • the particle size of the above-mentioned positive electrode active material is a well-known meaning in the art. It is measured by using a laser particle size analyzer to measure the volume particle size and distribution of the positive electrode active material.
  • a laser particle size analyzer for example, the Mastersizer3000 laser particle size analyzer of Malvern Instruments Co., Ltd. in the UK is used. .
  • the content ratio of the active material A, the active material B and the active material C is 1:0.5-8:0.1-10, optionally 1:0.8-6:0.2-8 , further optionally 1:1.5-6:3-8, the most preferred is 1:1.5-4:2.5-5. Therefore, through a specific proportion of each active material, the compaction density of the positive electrode sheet containing the positive electrode active material is further increased, which makes the corresponding battery have high energy density and safety while having good high-temperature cycle performance. and high temperature storage performance. The contents are based on the total weight of the cathode active material.
  • the sum of the contents of the active material A and the active material B is equal to the content of the active material C, and each content is based on the total weight of the cathode active material.
  • the specific content of each active material further enables the positive electrode sheet containing the positive electrode active material to have a high compaction density, which enables the corresponding battery to have high energy density and safety while also having good high-temperature cycle performance. and high temperature storage performance.
  • the content of the active material A is 2%-98% by weight, preferably 10%-90% by weight, further preferably 30%-70% by weight, more preferably 20%-60% by weight. , based on the total weight of the cathode active material.
  • the content of the active material B is 2%-98% by weight, preferably 10%-80% by weight, further preferably 15%-60% by weight, more preferably 20%-40% by weight, based on the positive electrode activity Total weight of material.
  • the content of the active material C is 2%-98% by weight, preferably 10%-80% by weight, further preferably 10%-70% by weight, more preferably 10%-50% by weight, based on the positive electrode activity Total weight of material.
  • the specific surface area of the cathode active material is 0.3-1.8m 2 /g, optionally 0.3-0.8m 2 /g, 0.6-0.8m 2 /g, 0.8-1.0m 2 /g, 1.0-1.8m 2 /g. Therefore, the cathode active material with a specific specific surface area and compacted density enables the corresponding battery to have high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • the active material A and/or the active material B and/or the active material C comprise M elements, where M is selected from the group consisting of Zr, Sr, B, Ti, Mg, Sn and Al. One or more, preferably Ti or Al. Therefore, by subjecting each active material to the above-mentioned treatment, the surface phase structure of the material can be stabilized, side reactions during the charge and discharge process can be suppressed, and the corresponding battery can further have high energy density, safety, and good high-temperature cycle performance. performance and high-temperature storage performance.
  • the active material A and/or the active material B and/or the active material C coat an M element, wherein M is as described above.
  • the coating is performed using methods known to those skilled in the art, such as dry coating or liquid phase coating.
  • x1:x2:x3 is 1: (0.73-1.37): (0.73-1.37)
  • the optional value is 1: (0.9-1.1): (0.9-1.1)
  • a1: a2: a3 is 1: (0.71-1.42): (0.31-1)
  • the optional value is 1: (0.95-1.11): ( 0.55-0.75). Therefore, by limiting the proportion of lithium and nickel in each active material, the corresponding battery can further achieve high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • active material A is a polycrystalline material
  • active materials B and C are single-crystal-like or single-crystalline materials.
  • the corresponding battery can further achieve high energy density and safety while also having good high-temperature cycle performance and high-temperature storage performance.
  • the term “quasi-single crystal” refers to primary particles with an average particle size Dv50 greater than 1 ⁇ m and a small amount of agglomeration.
  • the term “single crystal” refers to primary particles with an average particle size Dv50 greater than 1 ⁇ m and no obvious agglomeration, and with fewer grain boundaries.
  • the term “polycrystalline” refers to secondary particles consisting of primary particles.
  • the “primary particles” are usually in the form of single particles dispersed at the micron level; the “secondary particles” are usually in the form of many particles (100-500 nanometers) agglomerated to form a spherical shape with very many grain boundaries.
  • the single crystal cathode active material is a primary particle with a small surface area, high mechanical strength, high compaction density, and is not easily crushed.
  • the ratio of polycrystalline and monocrystalline nickel-containing active materials is properly formulated, not only the energy density of the battery can be guaranteed, but also the battery can have excellent high-temperature performance.
  • a second aspect of the application also provides a secondary battery, characterized in that:
  • the resulting battery has high energy density and safety, as well as good high-temperature cycle performance and high-temperature storage performance.
  • a secondary battery is provided.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode sheet 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 includes the positive electrode active material of the first aspect of the present application.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may also include cathode active materials known in the art for batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the weight ratio of the positive electrode active material in the positive electrode film layer is 80-100% by weight, based on the total weight of the positive electrode film layer count.
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the weight ratio of the binder in the positive electrode film layer is 0-20% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the weight ratio of the conductive agent in the positive electrode film layer is 0-20% by weight, based on the total weight of the positive electrode film layer.
  • 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 (such as N -methylpyrrolidone), forming a positive electrode slurry, wherein the solid content of the positive electrode slurry is 40-80wt%, the viscosity at room temperature is adjusted to 5000-25000mPa ⁇ s, and the positive electrode slurry is coated on the surface of the positive electrode current collector , dried and cold-pressed by a cold rolling mill to form a positive electrode piece; the unit area density of the positive electrode powder coating is 150-350 mg/m 2 , and the compacted density of the positive electrode piece is 3.0-3.6g/cm 3 , optionally 3.3 -3.5g/cm 3 .
  • the calculation formula of the compacted density is
  • Compaction density coating surface density / (thickness of electrode piece after extrusion - thickness of current collector).
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative 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, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide 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 oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the weight ratio of the negative active material in the negative electrode film layer is 70-100% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS polysodium acrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA methacrylic acid
  • CMCS carboxymethyl chitosan
  • the negative electrode film layer optionally further includes a conductive agent.
  • 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.
  • the weight ratio of the conductive agent in the negative electrode film layer is 0-20% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • the weight ratio of the other additives in the negative electrode film layer is 0-15% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water), forming a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70wt%, and the viscosity at room temperature is adjusted to 2000-10000mPa ⁇ s; the obtained negative electrode slurry is coated on the negative electrode current collector, After the drying process and cold pressing, such as against rollers, the negative electrode piece is obtained.
  • the negative electrode powder coating unit area density is 75-220mg/m 2
  • the negative electrode plate compacted density is 1.2-2.0g/m 3 .
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bisfluorosulfonyl Lithium amine (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoromethane borate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • the concentration of the electrolyte salt is usually 0.5-5mol/L.
  • the solvent may be selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) ), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate Ester (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) , one or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl
  • FEC
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the thickness of the isolation film is 6-40um, optionally 12-20um.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes 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 electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG. 6 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the mixture was prepared through coprecipitation reaction at pH 11.4 for 24 hours to obtain Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 , the precursor of small particle single crystal ternary cathode active material B.
  • 4mol/L sodium hydroxide 4mol/L sodium hydroxide
  • 0.4 mol/L ammonia water was used as a complexing agent, and the precursor Ni 0.55 Co 0.12 Mn 0.33 (OH ) 2 .
  • Preparation method of positive electrode active material A Place the precursor Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 and Li-containing compound LiOH ⁇ H 2 O at a high speed at a molar ratio of 1:1.05. Mix the materials in a mixer, and then place them in a kiln for sintering at 800°C for 5 hours. After cooling to room temperature, add them to an airflow mill and mechanically grind them for 5 hours to obtain the positive active material A Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 .
  • the above-mentioned positive electrode active material A and 0.3wt% Al 2 O 3 based on active material A were placed in a high-speed mixer for mixing, and then placed in a kiln for sintering at 500°C for 5 hours to form a package of positive electrode active material A.
  • the surface-modified cathode active material A is obtained by coating.
  • Preparation method of positive electrode active material B The precursor Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 and Li-containing compound LiOH ⁇ H 2 O are placed at a high speed at a molar ratio of 1:1.05. Mix the materials in a mixer, then place them in a kiln for sintering at 850°C for 5 hours. After cooling to room temperature, grind them mechanically with a jet mill for 5 hours to obtain the positive active material B Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 .
  • the above-mentioned positive electrode active material B and 0.2wt% of the compound Al 2 O 3 containing the coating element Al are placed in a plow roller/high-speed mixer for mixing, and then placed in a kiln for sintering at 500°C for 5 hours to form a positive electrode.
  • the coating layer of the active material B obtains the surface-modified cathode active material B.
  • Preparation method of positive electrode active material C The precursor Ni 0.55 Co 0.12 Mn 0.33 (OH) 2 of the above positive electrode active material C and the Li-containing compound lithium carbonate are placed in a high-speed mixer at a molar ratio of 1:1.1. The materials are mixed, and then placed in a kiln at 700°C for sintering for 5 hours. After cooling to room temperature, the mixture is mechanically ground by a jet mill for 5 hours to obtain the positive active material C Li(Ni 0.55 Co 0.12 Mn 0.33 )O 2 .
  • the mixture of the above-mentioned positive electrode active material C and 0.2wt% of alumina Al2O3 and titanium oxide TiO2 with a mass ratio of 1 :1 is placed in a high-speed mixer for mixing, and then placed in a kiln for 500°C After sintering for 5 hours, a coating layer of the positive electrode active material C is formed, that is, the surface-modified positive electrode active material C is obtained.
  • cathode active material A Put the above-mentioned cathode active material A, cathode active material B and cathode active material C into a high-speed mixer in a mass ratio of 7:2:1 and mix uniformly to obtain the cathode active material of the present invention. Its parameters are summarized in in FIG. 1.
  • the positive electrode active materials of Examples 2-19 and the positive electrode active materials of Comparative Examples 1-8 are similar to the preparation methods of the positive electrode active materials of Example 1, but the type, composition, particle size and crystal type of each active material are changed to produce different products. See Table 1 for parameters.
  • the cathode active material, conductive carbon black SP and binder PVDF of Preparation Example 1 were dispersed into the solvent NMP in a weight ratio of 98:1:1 and mixed evenly to obtain a cathode slurry; the cathode slurry was evenly coated on the cathode On the current collector aluminum foil, after drying and cold pressing, the positive electrode piece was obtained.
  • the coating amount per unit area was 0.27g/1540.25mm 2 ; its compacted density is summarized in Table 1.
  • the organic solvent is a mixed solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), where the volume ratio of EC, EMC and DEC is 20:20:60.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the concentration of lithium salt is 1mol/L.
  • the positive electrode sheet, isolation film, and negative electrode sheet in order so that the isolation film plays an isolation role between the positive and negative electrode sheets, then roll it into a square bare cell, put it into the aluminum-plastic film, and then heat it at 80 After baking at °C to remove water, the corresponding non-aqueous electrolyte is injected, sealed, and after standing, hot and cold pressing, formation, clamping, volume separation and other processes, the finished battery is obtained.
  • the secondary battery of Example 2-19 and the secondary battery of Comparative Example 1-8 are similar to the secondary battery of Example 1, but use the positive active material of the corresponding preparation example.
  • the gram capacity the capacity C of the battery (mAh)/the mass of the positive active material (g).
  • the positive active material only contains single crystal low-nickel active material C (Comparative Example 3)
  • the high-temperature cycle and high-temperature storage performance are better, but it cannot meet the demand for high energy density; mixing a certain proportion of single After crystallizing the high-nickel active material B (Comparative Example 6), its energy density is still low.
  • the mixed ternary cathode material can effectively solve the problem of high nickel active materials during cold pressing and circulation.
  • the particles break along the grain boundaries, the specific surface area increases, the electron/ion transmission path is destroyed, and the electrolysis Liquid corrosion and other problems; reduce side reactions such as gas production during high-temperature storage, so that the hybrid cathode has excellent high-temperature performance under high-capacity conditions.

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Abstract

本申请涉及一种正极活性材料，其包含活性材料A，其组成式为 Li x1Ni a1Co b1Mn c1O 2-y1Q y1 Ⅰ；活性材料B，其组成式为 Li x2Ni a2Co b2Mn c2O 2-y2Q y2 Ⅱ；和活性材料C，其组成式为 Li x3Ni a3Co b3Mn c3O 2-y3Q y3 Ⅲ；式I、II和III中，各下标如说明书中定义；其中所述活性材料A的平均粒径Dv50大于所述活性材料B的平均粒径Dv50，且大于所述活性材料C的平均粒径Dv50。本申请的正极活性材料压实密度大，使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。

Description

一种正极活性材料、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种正极活性材料、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。另外，由于正极活性材料的选择越发局限，高镍正极活性材料被认为是满足高能量密度要求的最佳选择。
但是随着镍含量的不断提高，其结构稳定性越来越差。通过包覆或掺杂等手段来改善材料的倍率性能和循环性能等是目前比较有效的手段，然而现有的方法均会导致对锂离子电池性能不同程度的破坏，例如，锂离子电池的克容量降低、循环性能变差等。因此，现有的包覆或掺杂的正极材料仍有待改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种正极活性材料，其相应极片的压实密度大，使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
为了达到上述目的，本申请的第一方面提供了一种正极活性材料，其包含
活性材料A，其组成式为
Li x1Ni a1Co b1Mn c1O 2-y1Q y1     Ⅰ
式Ⅰ中，0.95≤x1≤1.3，0.7≤a1≤0.99，0.01≤b1≤0.15，0.01≤c1≤0.3，a1+b1+c1＝1，0≤y1≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
活性材料B，其组成式为
Li x2Ni a2Co b2Mn c2O 2-y2Q y2     Ⅱ
式Ⅱ中，0.95≤x2≤1.3，0.7≤a2≤0.99，0.01≤b2≤0.15，0.01≤c2≤0.3，a2+b2+c2＝1，0≤y2≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；和
活性材料C，其组成式为
Li x3Ni a3Co b3Mn c3O 2-y3Q y3     Ⅲ
式Ⅲ中，0.95≤x3≤1.3，0.3≤a3<0.7，0.01≤b3≤0.15，0.01≤c3≤0.5，a3+b3+c3＝1，0≤y3≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
其中所述活性材料A的平均粒径Dv50大于所述活性材料B的平均粒径Dv50，且大于所述活性材料C的平均粒径Dv50。
由此，本申请的正极活性材料通过包含不同平均粒径和镍含量的活性材料A、B和C，使得其相应极片的压实密度大，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，活性材料A的平均粒径Dv50为7-15μm，可选为8-14μm；Dv90为15-25μm，可选为18-22μm；活性材料B的平均粒径Dv50为1-8μm，可选为2-5μm，Dv90为3-10μm，可选为5-8μm；活性材料C的平均粒径1-7μm，可选为2-5μm，Dv90为5-10μm，可选为5-8μm。由此，通过进一步限定各活性材料的平均粒径，进一步提高包含所述正极活性材料的正极极片的压实密度，使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，所述活性材料A、所述活性材料B和所述活性材料C的含量比为1：0.5-8：0.1-10，可选地为1：0.8-6：0.2-8，进一步可选为1：1.5-6：3-8。由此，通过特定比例的各活性材料，进一步使得包含所述正极活性材料的正极极片的压实密度大，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，所述活性材料A和所述活性材料B的含量之和等于所述活性材料C的含量，各自含量均基于所述正极活性材料的总重量计。由此，通过特定含量的各活性材料，进一步使得包含所述正极活性材料的正极极片的压实密度大，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，所述正极活性材料的比表面积为0.3-1.8m 2/g；压实密度为3.0-3.6g/cm 3。由此，具有特定比表面积和压实密度的正极活性材料使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，所述活性材料A和/或所述活性材料B和/或所述活性材料C包含M元素，其中M选自Zr、Sr、B、Ti、Mg、Sn及Al中的一种或多种。由此，通过将所述各活性材料经过上述处理，能够稳定材料表面相结构，抑制充放电过程中的副反应，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，在分别对应的所述活性材料A、所述活性材料B和所述活性材料C的化学式中，x1：x2：x3为1：(0.73-1.37)：(0.73-1.37)，a1：a2：a3为1：(0.71-1.42)：(0.31-1)。由此，通过限定各活性材料中锂和镍的比例，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在任意实施方式中，活性材料A为多晶材料，活性材料B和C为类单晶或单晶材料。由此，通过限定各活性材料的晶体类型，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
本申请的第二方面还提供一种二次电池，其特征在于，包括本申请的第一方面所述的正极活性材料。
由此，所得的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
本申请的第三方面提供一种电池模块，包括本申请的第二方面的二次电池。
本申请的第四方面提供一种电池包，包括本申请的第三方面的电池模块。
本申请的第五方面提供一种用电装置，包括选自本申请的第二方面的二次电池、本申请的第三方面的电池模块或本申请的第四方面的电池包中的至少一种。
本申请的正极活性材料通过包含不同平均粒径和镍含量的活性材料A、B和C，使得包含所述正极活性材料的正极极片的压实密度大，进而使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的正极活性材料及其制造方法、正极极片、二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)， 表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
目前，常规的高镍正极活性材料主要由二次颗粒以团聚、多晶的形式构成。对于所述高镍正极活性材料，随着Ni含量的增加，材料的克容量也随之升高，但高镍多晶二次颗粒材料还存在以下问题:1)堆积密度低，制成的极片压实密度低，进一步降低了电池的比能量；2)颗粒极易破碎，使得材料的比表面积增加、进而使得电池副反应增多、电池产气严重等问题。申请人研究发现本申请第一方面的正极活性材料通过包含不同平均粒径和镍含量的活性材料A、B和C，使得包含所述正极活性材料的正极极片的压实密度大，有效解决现有技术的高镍正极活性材料在冷压以及循环过程中的颗粒沿晶界破碎、比表面积增大、电子/离子传输路径破坏、电解液腐蚀等性能劣化问题，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
正极活性材料
本申请的一个实施方式中，本申请提出了
一种正极活性材料，其包含
活性材料A，其组成式为
Li x1Ni a1Co b1Mn c1O 2-y1Q y1      Ⅰ
式Ⅰ中，0.95≤x1≤1.3，0.7≤a1≤0.99，0.01≤b1≤0.15，0.01≤c1≤0.3，a1+b1+c1＝1，0≤y1≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
活性材料B，其组成式为
Li x2Ni a2Co b2Mn c2O 2-y2Q y2      Ⅱ
式Ⅱ中，0.95≤x2≤1.3，0.7≤a2≤0.99，0.01≤b2≤0.15，0.01≤c2≤0.3，a2+b2+c2＝1，0≤y2≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；和
活性材料C，其组成式为
Li x3Ni a3Co b3Mn c3O 2-y3Q y3      Ⅲ
式Ⅲ中，0.95≤x3≤1.3，0.3≤a3<0.7，0.01≤b3≤0.15，0.01≤c3≤0.5，a3+b3+c3＝1，0≤y3≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
其中所述活性材料A的平均粒径Dv50大于所述活性材料B的平均粒径Dv50，且大于所述活性材料C的平均粒径Dv50。
本申请人研究发现本申请的正极活性材料通过包含不同平均粒径和镍含量的活性材料A、B和C，使得包含所述正极活性材料的正极极片的压实密度大，同时有效解决现有技术的高镍正极活性材料在冷压以及循环过程中的颗粒沿晶界破碎、比表面积增大、电子/离子传输路径破坏、电解液腐蚀等性能劣化问题，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，活性材料A的平均粒径Dv50为7-15μm，可选为8-14μm；Dv90为15-25μm，可选为18-22μm；活性材料B的平均粒径Dv50为1-8μm，可选为2-5μm，Dv90为3-10μm，可选为5-8μm；活性材料C的平均粒径1-7μm，可选为2-5μm，Dv90为5-10μm，可选为5-8μm。由此，通过进一步限定各活性材料的平均粒径，进一步提高正极活性材料的压实密度，使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，所述活性材料A的Dv10为1-4μm，优选为2-3μm；Dv99为20-30μm，优选为24-28μm。
所述活性材料B的Dv10为1-3μm，优选为1-2μm；Dv99为4-12μm，优选为6-10μm。
所述活性材料C的Dv10为1-3μm，优选为1.5-2.5μm；Dv99为6-15μm，优选为7-13μm。
所述Dv10为样品的体积累计分布百分数达到10％时对应的粒径；Dv50为样品的体积累计分布百分数达到50％时对应的粒径，也称为平均粒径；Dv90为样品的体积累计分布百分数达到90％时对应的粒径；Dv99为样品的体积累计分布百分数达到99％时对应的粒径。
在一个优选的实施方式中，所述活性材料A的平均粒径Dv50为11.5-12.5μm，活性材料B的平均粒径Dv50为3.8-4.2μm；活性材料C的平均粒径Dv50为3.8-4.2μm。
上述正极活性材料的粒径尺寸为本领域公知的含义，其是以采用激光粒度分析仪测定正极活性材料的体积粒径及其分布，例如采用英国马尔文仪器有限公司的Mastersizer3000型激光粒度分析仪。
在一些实施方式中，所述活性材料A、所述活性材料B和所述活性材料C的含量比为1：0.5-8：0.1-10，可选地为1：0.8-6：0.2-8，进一步可选为1：1.5-6：3-8，最优选为1:1.5-4:2.5-5。由此，通过特定比例的各活性材料，进一步使得包含所述正极活性材料的正极极片的压实密度大，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。所述含量均基于所述正极活性材料的总重量计。
在一些实施方式中，所述活性材料A和所述活性材料B的含量之和等于所述活性材料C的含量，各自含量均基于所述正极活性材料的总重量计。由此，通过特定含量的各活性材料，进一步使得包含所述正极活性材料的正极极片的压实密度大，这使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，所述活性材料A的含量为2重量％-98重量％，优选10重量％-90重量％，进一步优选30重量％-70重量％，更优选20重量％-60重量％，基于所述正极活性材料的总重量计。所述活性材料B的含量为2重量％-98重量％，优选10重量％-80重量％，进一步优选15重量％-60重量％，更优选20重量％-40重量％，基于所述正极活性材料的总重量计。所述活性材料C的含量为2重量％-98重量％，优选10重量％-80重量％，进一步优选10重量％-70重量％，更优选10重量％-50重量％，基于所述正极活性材料的总重量计。
在一些实施方式中，所述正极活性材料的比表面积为0.3-1.8m 2/g，可选为0.3-0.8m 2/g、0.6-0.8m 2/g、0.8-1.0m 2/g、1.0-1.8m 2/g。由此，具有特定比表面积和压实密度的正极活性材料使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，所述活性材料A和/或所述活性材料B和/或所述活性材料C包含M元素，其中M选自Zr、Sr、B、Ti、Mg、Sn及Al中的一种或多种，优选为Ti或Al。由此，通过将所述各活性材料经过上述处理，能够稳定材料表面相结构，抑制充放电过程中的副反应，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，所述活性材料A和/或所述活性材料B和/或所述活性材料C包 覆M元素，其中M如上所述。所述包覆利用本领域技术人员已知的方法进行，例如干法包覆或者液相包覆法。
在一些实施方式中，在分别对应的所述活性材料A、所述活性材料B和所述活性材料C的化学式中，x1：x2：x3为1：(0.73-1.37)：(0.73-1.37)，可选为1：(0.9-1.1)：(0.9-1.1)，a1：a2：a3为1：(0.71-1.42)：(0.31-1)，可选为1：(0.95-1.11)：(0.55-0.75)。由此，通过限定各活性材料中锂和镍的比例，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在一些实施方式中，活性材料A为多晶材料，活性材料B和C为类单晶或单晶材料。由此，通过限定各活性材料的晶体类型，进一步使得相应的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
在本申请中，所述术语“类单晶”是指平均粒径Dv50大于1μm并且存在少量团聚的一次颗粒。所述术语“单晶”是指平均粒径Dv50大于1μm且无明显团聚的一次颗粒，具有较少的晶界。所述术语“多晶”是指由一次颗粒组成的二次颗粒。所述“一次颗粒”通常是微米级分散的单颗粒的形式；“二次颗粒”通常是以许多个颗粒(100-500纳米)团聚形成球形，具有非常多的晶界。单晶正极活性材料为一次颗粒，表面积小，机械强度大，压实密度大，不易压碎。当将多晶和单晶的含镍活性材料的比例进行合适的调配后，不仅可以保证电池的能量密度，还可以保证电池具有优异的高温性能。
本申请的第二方面还提供一种二次电池，其特征在于，
包括本申请的第一方面所述的正极活性材料。
由此，所得的电池具有高能量密度和安全性的同时，具有良好的高温循环性能和高温存储性能。
以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正 极膜层包括本申请第一方面的正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料还可包含本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。所述正极活性材料在正极膜层中的重量比为80-100重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。所述粘结剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料，其中所述正极浆料固含量为40-80wt％，室温下的粘度调整到5000-25000mPa·s，将正极浆料涂覆在正极集流体的表面，烘干后经过冷轧机冷压后形成正极极片；正极粉末涂布单位面密度为150-350mg/m 2，正极极片压实密度为3.0-3.6g/cm 3，可选为3.3-3.5g/cm 3。所述压实密度的计算公式为
压实密度＝涂布面密度/(挤压后极片厚度-集流体厚度)。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。所述负极活性材料在负极膜层中的重量比为70-100重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。所述粘结剂在负极膜层中的重量比为0-30重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在负极膜层中的重量比为0-20重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。所述其他助剂在负极膜层中的重量比为0-15重量％，基于负极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料，其中所述负极浆料固含量为30-70wt％，室温下的粘度调整到2000-10000mPa·s；将所得到的负极浆料涂覆在负极集流体上，经过干燥工序，冷压例如对辊，得到负极极片。负极粉末涂布单位面密度为75-220mg/m 2，负极极片压实密度1.2-2.0g/m 3。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。所述电解质盐的浓度通常为0.5-5mol/L。
在一些实施方式中，溶剂可选自氟代碳酸乙烯酯(FEC)、碳酸亚乙酯(EC)、碳酸亚丙基酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、 碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，所述隔离膜的厚度为6-40um，可选为12-20um。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个， 本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
为了使本申请所解决的技术问题、技术方案及有益效果更加清楚，以下将结合实施例和附图对本申请进行进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实 施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用的任何限制。基于本申请中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例都属于本申请保护的范围。
实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
一、制备实施例
正极活性材料的制备
制备实施例1
(1)正极活性材料前驱体制备：在连续搅拌釜式反应器容器中，将硫酸镍、硫酸锰、硫酸钴按摩尔比：Ni:Co:Mn＝8:1:1(基于各元素计)加入去离子水中，配置成总摩尔浓度2mol/L过渡金属盐溶液溶液，加入4mol/L氢氧化钠作为沉淀剂，0.4mol/L的氨水作为为络合剂，在pH为11.3下通过共沉淀反应24小时制备得到大颗粒锂多晶三元正极材料A的前驱体Ni 0.8Co 0.1Mn 0.1(OH) 2。将硫酸镍、硫酸锰、硫酸钴按摩尔比：
Ni:Co:Mn＝8:1:1加入去离子水中，配置成总摩尔浓度2mol/L过渡金属盐溶液溶液，加入4mol/L氢氧化钠作为沉淀剂，0.4mol/L的氨水作为为络合剂，在pH11.4下通过共沉淀反应24小时制备得到小颗粒单晶三元正极活性材料B的前驱体Ni 0.8Co 0.1Mn 0.1(OH) 2。将硫酸镍、硫酸锰、硫酸钴按摩尔比：Ni:Co:Mn＝55:12:33加入去离子水中，配置成总摩尔浓度2mol/L过渡金属盐溶液溶液，加入4mol/L氢氧化钠作为沉淀剂，0.4mol/L的氨水作为为络合剂，在pH11.4下通过共沉淀反应24小时制备得到小颗粒单晶三元正极活性材料C的前驱体Ni 0.55Co 0.12Mn 0.33(OH) 2。
(2)正极活性物质A的制备方法：将上述正极活性物质A的前驱体Ni 0.8Co 0.1Mn 0.1(OH) 2、含Li化合物LiOH·H 2O以摩尔比为1:1.05，置于高速混合机中进行混料，然后置于窑炉中800℃进行烧结5小时，冷却到室温后加入到气流磨通过机械研磨5小时即为正极活性物质A Li(Ni 0.8Co 0.1Mn 0.1)O 2。将上述正极活性物质A与基于活性物质A计的0.3wt％的Al 2O 3置于高速混合机中进行混料，然后置于窑炉中进行500℃烧结5h，形成正极活性物质A的包覆层，即得到表面修饰的正极活性物质A。
(3)正极活性物质B的制备方法：将上述正极活性物质B的前驱体Ni 0.8Co 0.1Mn 0.1(OH) 2、含Li化合物LiOH·H 2O以摩尔比为1:1.05，置于高速混合机中 进行混料，然后置于窑炉中850℃进行烧结5h，冷却到室温后通过气流磨机械研磨5小时即为正极活性物质B Li(Ni 0.8Co 0.1Mn 0.1)O 2。将上述正极活性物质B与0.2wt％的含包覆元素Al的化合物Al 2O 3置于犁刀辊/高速混合机中进行混料，然后置于窑炉中进行500℃烧结5h，形成正极活性物质B的包覆层，即得到表面修饰的正极活性物质B。
(4)正极活性物质C的制备方法：将上述正极活性物质C的前驱体Ni 0.55Co 0.12Mn 0.33(OH) 2、含Li化合物碳酸锂以摩尔比为1:1.1，置于高速混合机中进行混料，然后置于窑炉中700℃进行烧结5h，冷却到室温后通过气流磨机械研磨5小时即为正极活性物质C Li(Ni 0.55Co 0.12Mn 0.33)O 2。将上述正极活性物质C与0.2wt％的质量比为1:1的氧化铝Al 2O 3和氧化钛TiO 2的混合物置于高速混合机中进行混料，然后置于窑炉中进行500℃烧结5h，形成正极活性物质C的包覆层，即得到表面修饰的正极活性物质C。
(5)将上述正极活性物质A、正极活性物质B与正极活性物质C按质量比7：2：1的比例放入高速混合机均匀混合，得到本发明的正极活性材料，其各参数汇总于表1中。
实施例2-19的正极活性材料和对比例1-8的正极活性材料与实施例1的正极活性材料制备方法相似，但是改变各活性材料的种类、组成、粒径和晶体类型，不同的产品参数详见表1。
Figure PCTCN2022101030-appb-000001
Figure PCTCN2022101030-appb-000002
二、应用实施例
实施例1
1)正极极片的制备
将制备实施例1的正极活性材料、导电炭黑SP及粘结剂PVDF按照重量比98:1:1分散至溶剂NMP中进行混合均匀，得到正极浆料；将正极浆料均匀涂布于正极集流体铝箔上，经烘干、冷压后，得到正极极片，其单位面积的涂覆量为0.27g/1540.25mm 2；其压实密度汇总于表1中。
2)负极极片的制备
将负极活性材料石墨、增稠剂羧甲基纤维素钠、粘接剂丁苯橡胶、导电剂乙炔黑，按照质量比97:1:1:1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料；将负极浆料均匀涂覆在铜箔上；将铜箔在室温晾干后转移至120℃烘箱干燥1h，然后过冷压、分切得到负极片，其单位面积的涂覆量为0.17g/1540.25mm 2。
3)隔离膜
选用12μm厚的聚丙烯隔离膜。
4)电解液的制备
有机溶剂为含有碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)的混液，其中，EC、EMC和DEC的体积比为20:20:60。在含水量<10ppm的氩气气氛手套箱中，将充分干燥的锂盐LiPF6溶解于有机溶剂中，混合均匀，获得电解液。其中，锂盐的浓度为1mol/L。
5)电池的制备
将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，再卷绕成方形的裸电芯后，装入铝塑膜，然后在80℃下烘烤除水后，注入相应的非水电解液、封口，经静置、热冷压、化成、夹具、分容等工序后，得到成品电池。
实施例2-19的二次电池和对比例1-8的二次电池与实施例1的二次电池制备方法相似，但是使用对应的制备实施例的正极活性材料。
三、电池性能测试
1.高温循环性能测试
将电池置于60℃烘箱中，静置2h，待电池温度保持60℃进行充放电测试。1C电 流恒流充电到3.65V，继续恒压充电，直至充电电流小于0.05C后截止；暂停5min；1C电流恒流放电到2.8V；暂停5min。以上为电池的一个充放电循环，不断重复，直至电池容量衰减到初始值的80％，记录循环圈数。
2.高温产气测试
电池的高温产气测试方法将电池以1C满充电至4.35V后，于70℃恒温箱中静置30天。并通过排水法测定电池的初始体积与静置30天后的体积，得到电池的体积膨胀率。电池的体积膨胀率(％)＝(静置30天后的体积/初始体积-1)×100％。
3.电池的克容量测试
电池的容量测试将锂离子电池在25℃的恒温环境下静置2h，然后在2.8V～4.35V下，按照1/3C充电至4.35V，然后在4.35V下恒压充电至电流≤0.05mA，静置5min，然后按照1C放电至2.8V，记录该电池的容量C 放。
所述克容量＝所述电池的容量C 放(mAh)/正极活性材料的质量(g)。
4.高温存储性能测试
在25℃下，将电池以0.33C的倍率恒流充电至4.35V，再恒压充电至电流小于等于0.05C，再以0.33C倍率恒流放电至2.8V，测试得到电池的初始放电容量。在25℃下，将电池以0.33C的倍率恒流充电至4.35V，再恒压充电至电流小于等于0.05C，之后将满充状态的电池置入60℃的烘箱中存储60天。取出高温存储60天后的电池、并自然降温至25℃，以0.33C倍率恒流放电至2.8V，之后以0.33C的倍率恒流充电至4.35V，再恒压充电至电流小于等于0.05C，再以0.33C倍率恒流放电至2.8V，测试得到电池高温存储60天后的放电容量。
电池高温存储60天后的容量保持率(％)＝高温存储60天后的放电容量/初始放电容量×100％
三、各实施例、对比例测试结果
按照上述方法分别制备各实施例和对比例的电池，并测量各项性能参数，结果见下表2。
表2 各对比例和实施例的电池的相关性能
Figure PCTCN2022101030-appb-000003
通过上述实施例和对比例可得知当多晶高镍大颗粒占比大时，包含混合正极材料的电池的克容量明显提升，但由于其颗粒在高温条件下存在开裂，锂镍混排严重等问题导致其高温性能较差，产气等副反应严重致使体积膨胀率较高；镍含量越高比例越大其特征越明显。正极活性材料仅包含单晶低镍的活性材料C(对比例3)时，电池内副反应 较少，高温循环、高温存储性能较好，但无法满足高能量密度这一需求；混合一定比例单晶高镍的活性材料B(对比例6)后其能量密度仍较低。
通过合理调控混合A、B和C后使得混合三元正极材料能有效解决高镍活性材料在冷压以及循环过程中的颗粒沿晶界破碎，比表面积增大，电子/离子传输路径破坏，电解液腐蚀等问题；减少高温存储过程中的产气等副反应，使混合正极保证高容量的条件下兼具优良的高温性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (12)

  1. 一种正极活性材料，其包含
    活性材料A，其组成式为
    Li x1Ni a1Co b1Mn c1O 2-y1Q y1  Ⅰ
    式Ⅰ中，0.95≤x1≤1.3，0.7≤a1≤0.99，0.01≤b1≤0.15，0.01≤c1≤0.3，a1+b1+c1＝1，0≤y1≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
    活性材料B，其组成式为
    Li x2Ni a2Co b2Mn c2O 2-y2Q y2  Ⅱ
    式Ⅱ中，0.95≤x2≤1.3，0.7≤a2≤0.99，0.01≤b2≤0.15，0.01≤c2≤0.3，a2+b2+c2＝1，0≤y2≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；和
    活性材料C，其组成式为
    Li x3Ni a3Co b3Mn c3O 2-y3Q y3  Ⅲ
    式Ⅲ中，0.95≤x3≤1.3，0.3≤a3<0.7，0.01≤b3≤0.15，0.01≤c3≤0.5，a3+b3+c3＝1，0≤y3≤0.1；其中Q为选自S、N、F、Cl、Br及I中的一种或多种；
    其中所述活性材料A的平均粒径Dv50大于所述活性材料B的平均粒径Dv50，且大于所述活性材料C的平均粒径Dv50。
  2. 根据权利要求1所述的正极活性材料，其特征在于，活性材料A的平均粒径Dv50为7-15μm，可选为8-14μm；Dv90为15-25μm，可选为18-22μm；活性材料B的平均粒径Dv50为1-8μm，可选为2-5μm，Dv90为3-10μm，可选为5-8μm；活性材料C的平均粒径1-7μm，可选为2-5μm，Dv90为5-10μm，可选为5-8μm。
  3. 根据权利要求1或2所述的正极活性材料，其特征在于，所述活性材料A、所述活性材料B和所述活性材料C的含量比为1：0.5-8：0.1-10，可选地为1：0.8-6：0.2-8，进一步可选为1：1.5-6：3-8。
  4. 根据权利要求1-3中任一项所述的正极活性材料，其特征在于，所述活性材料A和所述活性材料B的含量之和等于所述活性材料C的含量，各自含量均基于所述正极活性材料的总重量计。
  5. 根据权利要求1-4中任一项所述的正极活性材料，其特征在于，所述正极活性材料的比表面积为0.3-1.8m 2/g；压实密度为3.0-3.6g/cm 3。
  6. 根据权利要求1-5中任一项所述的正极活性材料，其特征在于，所述活性材料A和/或所述活性材料B和/或所述活性材料C包含M元素，其中M选自Zr、Sr、B、Ti、 Mg、Sn及Al中的一种或多种。
  7. 根据权利要求1-6中任一项所述的正极活性材料，其特征在于，在分别对应于所述活性材料A、所述活性材料B和所述活性材料C的化学式中，x1：x2：x3为1：(0.73-1.37)：(0.73-1.37)，a1：a2：a3为1：(0.71-1.42)：(0.31-1)。
  8. 根据权利要求1-7中任一项所述的正极活性材料，其特征在于，活性材料A为多晶材料，活性材料B和C为类单晶或单晶材料。
  9. 一种二次电池，其特征在于，
    包括权利要求1-8中任一项所述的正极活性材料。
  10. 一种电池模块，其特征在于，包括权利要求9所述的二次电池。
  11. 一种电池包，其特征在于，包括权利要求10所述的电池模块。
  12. 一种用电装置，其特征在于，包括选自权利要求9所述的二次电池、权利要求10所述的电池模块或权利要求11所述的电池包中的至少一种。
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