WO2023193231A1 - 一种二次电池、相应正极活性材料的制备方法、电池模块、电池包和用电装置 - Google Patents

一种二次电池、相应正极活性材料的制备方法、电池模块、电池包和用电装置 Download PDF

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WO2023193231A1
WO2023193231A1 PCT/CN2022/085791 CN2022085791W WO2023193231A1 WO 2023193231 A1 WO2023193231 A1 WO 2023193231A1 CN 2022085791 W CN2022085791 W CN 2022085791W WO 2023193231 A1 WO2023193231 A1 WO 2023193231A1
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Prior art keywords
active material
positive electrode
battery
secondary battery
electrolyte
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PCT/CN2022/085791
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English (en)
French (fr)
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李振华
徐佳伟
傅寒立
吴夏逸
李星
牛少军
金海族
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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 EP22924599.8A priority Critical patent/EP4280302A1/en
Priority to PCT/CN2022/085791 priority patent/WO2023193231A1/zh
Publication of WO2023193231A1 publication Critical patent/WO2023193231A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M2010/4292—Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/002—Inorganic electrolyte
    • 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 secondary batteries, and in particular to a secondary battery, a preparation method of a corresponding positive active material, a battery module, a battery pack and an electrical device.
  • This application was made in view of the above problems, and its purpose is to provide a secondary battery that includes a positive active material containing A and B dicationic ions and the same dicationic salt electrolyte, and improves the positive electrode active material and negative electrode activity.
  • the stability of the material improves the cycle stability of the battery.
  • a first aspect of the present application provides a secondary battery, including (1) a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and containing a positive electrode active material; (2) ) electrolyte; characterized in that the positive active material is an active material containing A and B double cations with the following chemical formula
  • Me is selected from one or more elements including Mn, Fe, Ni, Co, V, Cu, and Cr;
  • M is selected from one or more types of Mn, Fe, Ni, and Co;
  • A is K or Na
  • B is Na or Li
  • the ionic radius of A is larger than that of B, and A and B are of different species;
  • x is 0.001-0.05
  • the electrolyte solution contains dicationic electrolyte salts A and B, where A and B have the same definitions as in the cathode active material.
  • the battery of the present application contains a positive active material containing A and B dications and the same dication salt electrolyte, which advantageously greatly improves its cycle performance.
  • the cation A with a larger radius plays a role in stabilizing the structure of the cathode active material and reducing the loss of the cathode active material.
  • the cation A with a larger radius is embedded into the negative active material through the electrolyte containing the ionic salt, supporting the structure of the negative active material, reducing the loss of active lithium ions, thereby improving the cycle performance of the battery.
  • the molar concentration ratio of the two cations in the electrolyte is greater than or equal to the stoichiometric ratio of the two cations in the cathode active material. This is more conducive to the stability of the negative active material, thereby improving the cycle stability of the battery.
  • the dicationic electrolyte salt is selected from at least one of inorganic salts and organic salts of two or more elements among lithium, sodium, and potassium, and the inorganic salt is selected from hexafluorophosphate, high At least one of chlorate, hexafluoroarsenate, tetrafluoroborate, and difluorophosphate; the organic salt is selected from dioxaloborate, oxalate difluoroborate, and bisfluorosulfonimide salt , at least one of bistrifluoromethylsulfonimide salts. This makes the electrolyte more conducive to transporting double cations and improving the cycle stability of the battery.
  • the cathode active material of the chemical formula Ax B 1-x MeO 2 is selected from the group consisting of Ax B 1-x NiO 2 , Ax B 1-x MnO 2 , and Ax B 1-x CoO 2. At least one of the active materials of A x B 1-x Ni y Co z Mn 1-yz O 2 and A x B 1-x Ni y Co z Al 1-yz O 2 and their coating and doping products species; where A, B and x are defined as above; 0 ⁇ z ⁇ 1, 0 ⁇ y ⁇ 1.
  • the cycle stability of the secondary battery is improved.
  • the cathode active material of the chemical formula AxB 1- xMPO 4 is selected from at least one active material of the chemical formula AxB 1-xFePO 4 and AxB 1-x CoPO 4 ;where A, B and x are defined as above.
  • A, B and x are defined as above.
  • a second aspect of the present application also provides a method for preparing the cathode active material for a secondary battery according to the first aspect of the present application, which includes the following steps:
  • Me or M, A, and B are as defined in the first aspect of this application.
  • the positive active material required for the battery of the first aspect of the present application can be prepared, and the structural stability of the positive active material is improved, thereby improving the cycle stability of the secondary battery.
  • the A metal salt and the B metal salt are at least one of a carbonate and a hydroxide.
  • the active material of the present application can be obtained to improve the cycle stability of the secondary battery.
  • the molar ratio of the precursor to the A metal salt or B metal salt is 105% to 109% of their stoichiometric ratio.
  • a third aspect of the present application provides a battery module including the secondary battery of the first 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 first 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 battery of the present application advantageously greatly improves its cycle performance by including a positive active material containing A and B dications and the same dication salt electrolyte.
  • the cation A with a larger radius plays a role in stabilizing the structure of the cathode active material and reducing the loss of the cathode active material.
  • the A and B double cations of the double cation positive active material can be embedded into the negative active material through the double cation salt electrolyte, in which the cation A with a larger ionic radius plays a supporting role in the negative active material, thereby Reducing the expansion/shrinkage of the negative active material caused by ions B with a smaller ionic radius during the intercalation/extraction process is beneficial to improving the stability of the SEI film (solid electrolyte interphase, solid electrolyte phase boundary film) and reducing the consumption of active lithium ions, thus Improve battery cycle stability
  • 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).
  • the secondary battery of the first aspect of the present application advantageously improves its cycle performance by using a positive active material containing cations with a larger radius and using an electrolyte containing the ionic salt.
  • cations with a larger radius play a role in stabilizing the structure of the cathode active material and reducing the loss of the cathode active material.
  • cations with a larger radius are embedded into the negative active material through the electrolyte containing the ionic salt, supporting the structure of the negative active material, reducing the loss of active lithium ions, thereby improving the cycle performance of the battery.
  • the present application proposes a secondary battery, including (1) a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector and containing a positive electrode active material layer; (2) electrolyte; characterized in that the positive active material is an active material containing A and B double cations with the following chemical formula
  • Me is selected from one or more elements including Mn, Fe, Ni, Co, V, Cu, and Cr;
  • M is selected from one or more types of Mn, Fe, Ni, and Co;
  • A is K or Na
  • B is Na or Li
  • the ionic radius of A is larger than that of B, and A and B are of different species;
  • x is 0.001-0.05, preferably 0.001-0.025;
  • the electrolyte solution contains dicationic electrolyte salts A and B, where A and B have the same definitions as in the cathode active material.
  • the present application unexpectedly discovered that the battery of the present application contains a positive active material containing A and B dications and the same dication salt electrolyte, which advantageously greatly improves its cycle performance.
  • the cation A with a larger radius plays a role in stabilizing the structure of the cathode active material and reducing the loss of the cathode active material.
  • the cation A with a larger radius is embedded into the negative active material through the electrolyte containing the ionic salt, supporting the structure of the negative active material, reducing the loss of active lithium, thereby improving the cycle performance of the battery.
  • the cations of the dicationic electrolyte salt are the same as the cations in the cathode active material; and the molar concentration ratio of the two cations in the electrolyte is greater than or equal to the stoichiometric ratio of the two cations in the cathode active material. This is more conducive to the stability of the negative active material, thereby improving the cycle stability of the battery.
  • the double-cation electrolyte salt refers to the electrolyte salt used in the electrolyte solution containing the same two cations as those in the positive active material, that is, a mixture of A and B cation salts.
  • the dicationic electrolyte salt is selected from at least one of inorganic salts and organic salts of two or more elements among lithium, sodium, and potassium, and the inorganic salt is selected from hexafluorophosphate, high At least one of chlorate, hexafluoroarsenate, tetrafluoroborate and difluorophosphate, optionally hexafluorophosphate; the organic salt is selected from dioxaloborate and oxalic difluoroborate. At least one of salt, bisfluorosulfonimide salt, and bistrifluoromethylsulfonimide salt. This makes the electrolyte more conducive to transporting double cations and improving the cycle stability of the battery.
  • the cycle stability of the secondary battery is improved.
  • the cathode active material of the chemical formula AxB 1-xMPO 4 is selected from the group consisting of active materials with the chemical formulas AxB 1-xFePO 4 , AxB 1-xCoPO 4 and their coatings and At least one of the doped products, wherein A, B, and x are as defined above; optionally an active material of the chemical formula A x B 1-x FePO 4 , wherein A, B, and x are as defined above.
  • the cycle stability of the secondary battery is improved.
  • a second aspect of the present application also provides a method for preparing the cathode active material for a secondary battery according to the first aspect of the present application, which includes the following steps:
  • Me or M, A, and B are as defined in the first aspect of this application.
  • the positive active material required for the battery of the first aspect of the present application can be prepared, and the structural stability of the positive active material is improved, thereby improving the cycle stability of the secondary battery.
  • the Me or M transition metal precursor may be commercially available or may be prepared according to methods known to those skilled in the art.
  • metal salt A and metal salt B are at least one of carbonate and hydroxide, optionally carbonate.
  • the active material of the present application can be obtained to improve the cycle stability of the secondary battery.
  • the molar ratio of the precursor to the A metal salt or B metal salt is 105% to 109% of their stoichiometric ratio.
  • step 2) the calcination is usually performed in a high-temperature furnace, first pre-calcining at a low temperature of 300-600°C for 3-7 hours, and then heating to a high temperature of 700-900°C for 9 -15 hours.
  • the secondary battery includes (1) a negative electrode sheet, which includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and containing a negative electrode active material; (2) a positive electrode electrode sheet, which includes a positive electrode current collector and a positive electrode membrane layer disposed on at least one surface of the positive electrode current collector and containing a positive electrode active material; (3) electrolyte; characterized in that the positive electrode active material and the electrolyte have the above stated definition.
  • a secondary battery typically includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode sheet and the negative electrode sheet. 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 as described above.
  • 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 positive active material is a positive active material containing A and B dications as described above.
  • the preparation method of the positive active material is as described in the second aspect of the application.
  • 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 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 positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, conductive agent, binder and any other components in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methyl pyrrolidone
  • 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, etc., and may be artificial graphite or natural graphite.
  • 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 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).
  • 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 negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • 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) , to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • 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 is a dicationic electrolyte salt as described in the first aspect of the application.
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate, dimethyl carbonate (DMC), dipropyl carbonate, carbonic acid Methyl propyl ester, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate , at least one of methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • fluoroethylene carbonate methyl formate
  • 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 positive electrode sheet, the negative electrode sheet 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 sheet, the negative electrode sheet 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.
  • This device is usually required to be thin and light, and secondary batteries can be used as power sources.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor and lithium carbonate at a molar ratio of 1:1.07, and grind it with an agate mortar.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining for 5 hours from room temperature to 500°C, then rising to high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooling to room temperature; LiNi 0.5 Co 0.2 Mn 0.3 O 2 is obtained Material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:1.06679:0.0032 and grind it.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining for 5 hours from room temperature to 500°C, then rising to high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooling to room temperature to collect Na 0.003 Li 0.997 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Example 1.2 Dual-cation cathode active material Na 0.015 Li 0.985 Ni 0.5 Co 0.2 Mn 0.3 O 2
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:1.054:0.016 and grind it.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then raising to high temperature of 800°C and calcining for 12 hours respectively, with a heating rate of 3°C min -1 , then cooling to room temperature and collecting Na 0.0015 Li 0.985 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:1.0432:0.0268 and grind it.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then rising to high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooling to room temperature to collect Na 0.025 Li 0.975 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:1.0379:0.0321 and grind it.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then rising to high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooling to room temperature to collect Na 0.03 Li 0.97 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:1.0165:0.0535 and grind it.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then rising to high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooling to room temperature to collect Na 0.05 Li 0.95 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate and potassium carbonate in a molar ratio of 1:1.06679:0.0032 and grind them.
  • the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination. loss.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then raising to high temperature of 800°C and calcining for 12 hours respectively, with a heating rate of 3°C min -1 , and then cooling to room temperature and collecting K 0.003 Li 0.997 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor with lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1.06679:0.0016:0.0016 and grind it.
  • the excess lithium carbonate is to make up for the lithium losses during high temperature calcination.
  • the fully ground solid powder is transferred to the crucible and placed in a programmed temperature muffle furnace for calcination.
  • the calcination procedure is: pre-calcining from room temperature to 500°C for 5 hours, then rising to high temperature of 800°C and calcining for 12 hours respectively, with a heating rate of 3°C min -1 , and then cooling to room temperature to collect Na 0.0015 K 0.0015 Li 0.997 Ni 0.5 Co 0.2 Mn 0.3 O 2 material.
  • the negative active material artificial graphite, conductive agent acetylene black, and binder SBR+CMC according to the weight ratio of 95:1.5:3.1:0.4, add the solvent deionized water, stir thoroughly and mix evenly to obtain the negative electrode slurry, and then apply it on On both surfaces of the negative electrode current collector copper foil, the coating weight per unit area of the negative electrode diaphragm is 0.140g/1540.25mm 2 (based on the weight excluding solvent).
  • the negative electrode sheet is obtained after drying and cold pressing.
  • Polyethylene porous membrane is used as the isolation membrane.
  • the positive electrode sheet, isolation film, and negative electrode sheet in order so that the isolation film is between the positive and negative electrodes for isolation, and wind them to obtain a bare cell. Place the bare battery core in the outer packaging, inject electrolyte and encapsulate it to obtain a secondary battery, and perform performance testing.
  • the secondary batteries of Examples 2 to 11 and the secondary batteries of Comparative Examples 1-2 are similar to the secondary batteries of Example 1, but the compositions of the battery positive active materials and the electrolyte are adjusted. For details on different product parameters, see Table 1.
  • the cycle performance of the cell is improved.
  • the doping amount increases, the cycle performance of the battery first increases and then decreases.
  • the sodium doping amount is optimal at 0.025. The doping of sodium ions and potassium ions improves the structural stability of the cathode active material and thereby improves the cycle performance of the battery.
  • the positive electrode active material containing sodium ions can significantly improve the cycle performance of the secondary battery.
  • the sodium ions in the positive active material can be embedded into the graphite layer through the electrolyte, playing a supporting role and reducing the expansion/shrinkage caused by the insertion/extraction of lithium ions, thereby reducing SEI damage and reducing activity. Lithium loss improves battery cycle performance.
  • the incorporation of ions with a larger radius into the cathode active material and the electrolyte containing the ion salt will help greatly improve the cycle performance of the battery.
  • ion doping with a larger radius stabilizes the layered structure of the cathode and reduces material loss.
  • ions with a larger radius are embedded into the graphite material through the electrolyte containing the ionic salt, supporting the graphite layer structure, reducing the loss of active lithium, and improving the cycle performance of the battery.

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Abstract

本申请涉及一种二次电池，包含(1)正极极片；(2)电解液；其特征在于，所述正极活性材料为具有以下化学式的含A、B双阳离子的活性材料A xB 1-xMeO 2或A xB 1-xMPO 4，其中Me、M、A、B、x具有说明书中所述定义；并且所述电解液包含A、B双阳离子电解质盐，其中A、B与所述正极活性材料中的定义相同；以及相应的正极活性材料的制备方法、相应的电池模块、电池包和用电装置。本申请的二次电池包含含A、B双阳离子的正极活性材料和相同的双阳离子盐电解液，提升了正极活性材料和负极活性材料的稳定性，从而改善了电池的循环稳定性。

Description

一种二次电池、相应正极活性材料的制备方法、电池模块、电池包和用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种二次电池、相应正极活性材料的制备方法、电池模块、电池包和用电装置。
背景技术
近年来，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源***，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。由于二次电池，特别是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，对正极活性材料的结构进行调整被本领域技术人员研究得越来越多。
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电池性能不同程度的破坏，例如，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活性材料仍有待改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种二次电池，其包含含A、B双阳离子的正极活性材料和相同的双阳离子盐电解液，提升了正极活性材料和负极活性材料的稳定性，从而改善了电池的循环稳定性。
本申请的第一方面提供了一种二次电池，包含(1)正极极片，其包括正极集流体以及设置在正极集流体的至少一个表面上且含有正极活性材料的正极膜层；(2)电解液；其特征在于，所述正极活性材料为具有以下化学式的含A、B双阳离子的活性材料
A xB 1-xMeO 2或A xB 1-xMPO 4，
其中
Me选自Mn、Fe、Ni、Co、V、Cu、Cr元素中的一种或多种；
M选自Mn、Fe、Ni、Co中的一种或多种；
A为K或Na,
B为Na或Li；
其中A的离子半径大于B，并且A与B种类不同；
x为0.001-0.05；并且
所述电解液包含A、B双阳离子电解质盐，其中A、B与所述正极活性材料中的定义相同。
由此，本申请的电池包含含A、B双阳离子的正极活性材料和相同的双阳离子盐电解液，有利地大幅提升了其循环性能。一方面，半径较大的阳离子A起到稳定正极活性材料结构作用，降低正极活性材料的损失。另一方面，半径较大的阳离子A通过含该离子盐的电解液嵌入负极活性材料中，支撑负极活性材料的结构，减少活性锂离子损失，从而提高了电池的循环性能。
在任意实施方式中，所述电解液中两种阳离子的摩尔浓度比大于等于正极活性材料中的两种阳离子的化学计量比。由此更有利于负极活性材料的稳定，从而提高电池的循环稳定性。
在任意实施方式中，所述双阳离子电解质盐选自锂、钠、钾中的两种或更多种元素的无机盐和有机盐中的至少一种，无机盐选自六氟磷酸盐、高氯酸盐、六氟砷酸盐、四氟硼酸盐、二氟磷酸盐中的至少一种；有机盐选自二草酸硼酸盐、草酸二氟硼酸盐、双氟磺酰亚胺盐、双三氟甲基磺酰亚胺盐中的至少一种。由此使得电解液更有利于传输双阳离子，提高电池的循环稳定性。
在任意实施方式中，所述化学式A xB 1-xMeO 2的正极活性材料选自化学式为A xB 1-xNiO 2、A xB 1-xMnO 2、A xB 1-xCoO 2、A xB 1-xNi yCo zMn 1-y-zO 2、A xB 1-xNi yCo zAl 1-y-zO 2的活性材料及其包覆和掺杂产物中的至少一种；其中A、B和x如上所述定义；0≤z≤1，0≤y≤1。由此通过包含所述特定的正极活性材料，改善了二次电池的循环稳定性。
在任意实施方式中，所述化学式A xB 1-xMPO 4的正极活性材料选自化学式为A xB 1-xFePO 4、A xB 1-xCoPO 4的活性材料中的至少一种；其中A、B和x如上所述所定义。由此通过包含所述特定的正极活性材料，改善了二次电池的循环稳定性。
本申请的第二方面还提供一种制备本申请的第一方面所述的二次电池用的正极活性材料的方法，其包括以下步骤：
1)提供Me或M过渡金属的前驱体。
2)将所述前驱体与A金属盐、B金属盐混合均匀，研磨；然后将研磨后的粉末进行煅烧，之后冷却至室温，得到所述正极活性材料；
其中Me或M、A、B如本申请的第一方面所定义。
由此，可制备本申请的第一方面的电池所需的正极活性材料，提高了正极活性材料的结构稳定性，从而提高了二次电池的循环稳定性。
在任意实施方式中，A金属盐、B金属盐为碳酸盐、氢氧化物中的至少一种。由此通过所述类型的金属盐，可以获得本申请的活性材料，以提高二次电池的循环稳定性。
在任意实施方式中，所述前驱体与A金属盐或B金属盐的摩尔比为其化学计量比的105％-109％。此通过所述比例的前驱体与A金属盐或B金属盐，可以获得本申请的活性材料，以提高二次电池的循环稳定性。
本申请的第三方面提供一种电池模块，包括本申请的第一方面的二次电池。
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一方面的二次电池、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。
本申请的电池通过包含含A、B双阳离子的正极活性材料和相同的双阳离子盐电解液，有利地大幅提升了其循环性能。一方面，半径较大的阳离子A起到稳定正极活性材料结构作用，降低正极活性材料的损失。另一方面，所述双阳离子正极活性材料的A、B双阳离子可以通过双阳离子盐电解液嵌入到负极活性材料中，其中离子半径较大的阳离子A在负极活性材料中起到支撑作用，从而降低离子半径较小的离子B在嵌入/脱出过程中引起的负极活性材料的膨胀/收缩，有利于提高SEI膜(solid electrolyte interphase，固体电解质相界膜)稳定性，降低活性锂离子消耗，从而提高电池的循环稳定性
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一种二次电池、相应正极活性材料的制备方法正极片、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)。
由于正极活性材料的选择越发局限，对正极活性材料的结构进行调整被本领域技术人员研究得越来越多。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电池性能不同程度的破坏，例如，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活性材料仍有待改进。发明人研究发现，本申请的第一方面的二次电池通过使用包含半径较大的阳离子的正极活性材料，并搭配含该离子盐的电解液，有利地大幅提升了其循环性能。一方面，半径较大的阳离子起到稳定正极活性材料结构作用，降低正极活性材料的损失。另一方面，半径较大的阳离子通过含该离子盐的电解液嵌入负极活性材料中，支撑负极活性材料的结构，减少活性锂离子损失，从而提高了电池的循环性能。
二次电池
本申请的一个实施方式中，本申请提出了一种二次电池，包含(1)正极极片，其包括正极集流体以及设置在正极集流体的至少一个表面上且含有正极活性材料的正极膜层；(2)电解液；其特征在于，所述正极活性材料为具有以下化学式的含A、B双阳离子的活性材料
A xB 1-xMeO 2或A xB 1-xMPO 4，
其中
Me选自Mn、Fe、Ni、Co、V、Cu、Cr元素中的一种或多种；
M选自Mn、Fe、Ni、Co中的一种或多种；
A为K或Na,
B为Na或Li；
其中A的离子半径大于B，并且A与B种类不同；
x为0.001-0.05，优选0.001-0.025；并且
所述电解液包含A、B双阳离子电解质盐，其中A、B与所述正极活性材料中的定义相同。
不囿于任何理论，本申请出乎意料地发现，本申请的电池包含含A、B双阳离子的正极活性材料和相同的双阳离子盐电解液，有利地大幅提升了其循环性能。一方面，半径较大的阳离子A起到稳定正极活性材料结构作用，降低正极活性材料的损失。另一方面，半径较大的阳离子A通过含该离子盐的电解液嵌入负极活性材料中，支撑负极活性材料的结构，减少活性锂损失，从而提高了电池的循环性能。
在一些实施方式中，双阳离子电解质盐的阳离子与正极活性材料中的阳离子相同；并且所述电解液中两种阳离子的摩尔浓度比大于等于正极活性材料中的两种阳离子的化学计量比。由此更有利于负极活性材料的稳定，从而提高电池的循环稳定性。
在一些实施方式中，所述双阳离子电解质盐是指电解液中使用的电解质盐包含与正极活性材料中相同的两种阳离子，即为A、B阳离子盐的混合物。
在一些实施方式中，所述双阳离子电解质盐选自锂、钠、钾中的两种或更多种元素的无机盐和有机盐中的至少一种，无机盐选自六氟磷酸盐、高氯酸盐、六氟砷酸盐、四氟硼酸盐、二氟磷酸盐中的至少一种，可选地为六氟磷酸盐；有机盐选自二草酸硼酸盐、草酸二氟硼酸盐、双氟磺酰亚胺盐、双三氟甲基磺酰亚胺盐中的至少一种。由此使得电解液更有利于传输双阳离子，提高电池的循环稳定性。
在一些实施方式中，所述化学式A xB 1-xMeO 2的正极活性材料选自化学式为A xB 1-xNiO 2、A xB 1-xMnO 2、A xB 1-xCoO 2、A xB 1-xNi yCo zMn 1-y-zO 2、A xB 1-xNi yCo zAl 1-y-zO 2的活性材料及其包覆和掺杂产物中的至少一种，其中A、B和x如上所述定义；0≤z≤1，0≤y≤1；可选为化学式A xB 1-xNi yCo zMn 1-y-zO 2的活性材料，其中A、B和x如上所述定义，y＝0.5，z＝0.2。由此通过包含所述特定的正极活性材料，改善了二次电池的循环稳定性。
在一些实施方式中，所述化学式A xB 1-xMPO 4的正极活性材料选自化学式为A xB 1-xFePO 4、A xB 1-xCoPO 4的活性材料及其包覆和掺杂产物中的至少一种，其中A、B和x如上所述定义；可选化学式为A xB 1-xFePO 4的活性材料，其中A、B和x如上所述 定义。由此通过包含所述特定的正极活性材料，改善了二次电池的循环稳定性。
本申请的第二方面还提供一种制备本申请的第一方面所述的二次电池用的正极活性材料的方法，其包括以下步骤：
1)提供Me或M过渡金属的前驱体。
2)将所述前驱体与A金属盐、B金属盐混合均匀，研磨；然后将研磨后的粉末进行煅烧，之后冷却至室温，得到所述正极活性材料；
其中Me或M、A、B如本申请的第一方面所定义。
由此，可制备本申请的第一方面的电池所需的正极活性材料，提高了正极活性材料的结构稳定性，从而提高了二次电池的循环稳定性。
在一些实施方式中，所述Me或M过渡金属的前驱体可为市售的或者可根据本领域技术人员已知的方法制备。
在一些实施方式中，A金属盐、B金属盐为碳酸盐、氢氧化物中的至少一种，可选为碳酸盐。由此通过所述类型的金属盐，可以获得本申请的活性材料，以提高二次电池的循环稳定性。
在一些实施方式中，所述前驱体与A金属盐或B金属盐的摩尔比为其化学计量比的105％-109％。此通过所述比例的前驱体与A金属盐或B金属盐，可以获得本申请的活性材料，以提高二次电池的循环稳定性。
在一些实施方式中，在步骤2)中，所述煅烧通常在高温炉中进行，先在300-600℃的低温下预煅烧3-7小时，然后升温至700-900℃的高温下煅烧9-15小时。
在一些实施方式中，所述二次电池包含(1)负极极片，其包括负极集流体以及设置在负极集流体的至少一个表面上且含有负极活性材料的负极膜层；(2)正极极片，其包括正极集流体以及设置在正极集流体的至少一个表面上且含有正极活性材料的正极膜层；(3)电解液；其特征在于，所述正极活性材料和所述电解液具有如上所述的定义。
通常情况下，二次电池包括正极片、负极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极片和负极片之间往返嵌入和脱出。电解质在正极片和负极片之间起到传导离子的作用。隔离膜设置在正极片和负极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极片]
正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，所述正极膜层包括如上所述的正极活性材料。
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，正极活性材料为如上所述的含A、B双阳离子的正极活性材料
所述正极活性材料的制备方法如本申请的第二方面所述。
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。
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。
在一些实施方式中，可以通过以下方式制备正极片：将上述用于制备正极片的组分，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；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极片。
[负极片]
负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，可选为人造石墨或天然石墨。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。
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。
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。
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。
在一些实施方式中，可以通过以下方式制备负极片：将上述用于制备负极片的组分，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；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极片。
[电解质]
电解质在正极片和负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，所述电解质盐为本申请的第一方面中所述的双阳离子电解质盐。
在一些实施方式中，溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯、碳酸甲乙酯(EMC)、碳酸二乙酯、碳酸二甲酯(DMC)、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
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，正极片、负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。正极片、负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***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、正极活性材料制备
对比例1.1单阳离子正极活性材料LiNi 0.5Co 0.2Mn 0.3O 2制备
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂按摩尔比1:1.07的比例混合均匀，用玛瑙研钵研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5h，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温；得到LiNi 0.5Co 0.2Mn 0.3O 2材料。
对比例1.2磷酸铁锂正极活性材料制备LiFePO 4
将摩尔比1：1：1的碳酸锂、硝酸铁和磷酸二氢铵加入到硝酸溶液中，并加入柠檬酸络合剂，调节pH＝3,加入葡萄糖组成的碳源，碳源的质量占碳酸锂、硝酸铁和磷酸二氢铵三者总质量的25％。搅拌混合均匀得到混合溶液，混合溶液发生放热反应并将混合溶液蒸干后得到前驱体；将前驱体在150℃下真空干燥12小时后，球磨粉碎。
取1kg经球磨粉碎后的前驱体，在气氛炉中于氮气保护气氛下，按照2℃/min速率升温至500℃下进行第一次烧结，烧结时间为4小时，然后按照10℃/min速率升温至700℃，并通入质量分数为80％的乙醇-水混合物气体200mL，进行第二次烧结后，烧结时间为8h，自然冷却后收集得到LiFePO 4材料成品。
实施例1.1 双阳离子正极活性材料Na 0.003Li 0.997Ni 0.5Co 0.2Mn 0.3O 2制备
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠按摩尔比1:1.06679：0.0032的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.003Li 0.997Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.2 双阳离子正极活性材料Na 0.015Li 0.985Ni 0.5Co 0.2Mn 0.3O 2
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠按摩尔比1:1.054：0.016的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.0015Li 0.985Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.3 双阳离子正极活性材料Na 0.025Li 0.975Ni 0.5Co 0.2Mn 0.3O 2制备
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠按摩尔比1:1.0432：0.0268的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.025Li 0.975Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.4 双阳离子正极活性材料Na 0.03Li 0.97Ni 0.5Co 0.2Mn 0.3O 2制备
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠按摩尔比1:1.0379：0.0321的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.03Li 0.97Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.5 双阳离子正极活性材料Na 0.05Li 0.95Ni 0.5Co 0.2Mn 0.3O 2制备
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠按摩尔比1:1.0165：0.0535的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.05Li 0.95Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.6 双阳离子为Li、K的正极活性材料K 0.003Li 0.997Ni 0.5Co 0.2Mn 0.3O 2
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钾按摩尔比1:1.06679：0.0032的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1， 之后冷却至室温后收集K 0.003Li 0.997Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.7 三阳离子K、Na的正极活性材料Na 0.0015K 0.0015Li 0.997Ni 0.5Co 0.2Mn 0.3O 2
将市售的Ni 0.5Co 0.2Mn 0.3(OH) 2前驱体与碳酸锂、碳酸钠、碳酸钾按摩尔比1:1.06679：0.0016：0.0016的比例混合均匀，研磨，过量的碳酸锂是为了弥补锂在高温煅烧中的损失。将充分研磨后的固体粉末转移至坩埚，置于程序升温的马弗炉中煅烧。煅烧程序为：从室温升到500℃预煅烧5小时，再分别升到高温800℃下煅烧12小时，升温速率为3℃ min -1，之后冷却至室温后收集Na 0.0015K 0.0015Li 0.997Ni 0.5Co 0.2Mn 0.3O 2材料。
实施例1.8 磷酸铁锂钠类双阳离子正极活性材料制备Na 0.003Li 0.997FePO 4
将摩尔比0.003:0.997：1：1的碳酸锂、碳酸钠、硝酸铁和磷酸二氢铵加入到硝酸溶液中，并加入柠檬酸络合剂，调节pH＝3,加入葡萄糖组成的碳源，碳源的质量占碳酸锂、硝酸铁和磷酸二氢铵三者总质量的25％。搅拌混合均匀得到混合溶液，混合溶液发生放热反应并将混合溶液蒸干后得到前驱体；将前驱体在150℃下真空干燥12小时后，球磨粉碎。
取1kg经球磨粉碎后的前驱体，在气氛炉中于氮气保护气氛下，按照2℃/min速率升温至500℃下进行第一次烧结，烧结时间为4小时，然后按照10℃/min速率升温至700℃，并通入质量分数为80％的乙醇-水混合物气体200mL，进行第二次烧结后，烧结时间为8小时，自然冷却后收集得到Na 0.003Li 0.997FePO 4材料成品。
实施例1.9 磷酸铁锂钠钾类双阳离子正极活性材料制备K 0.0015Na 0.0015Li 0.997FePO 4
将摩尔比0.0015:0.0015:0.997：1：1的碳酸锂、碳酸钠、碳酸钾、硝酸铁和磷酸二氢铵加入到硝酸溶液中，并加入柠檬酸络合剂，调节pH＝3,加入葡萄糖组成的碳源，碳源的质量占碳酸锂、硝酸铁和磷酸二氢铵三者总质量的25％。搅拌混合均匀得到混合溶液，混合溶液发生放热反应并将混合溶液蒸干后得到前驱体；将前驱体在150℃下真空干燥12小时后，球磨粉碎。
取1kg经球磨粉碎后的前驱体，在气氛炉中于氮气保护气氛下，按照2℃/min速率升温至500℃下进行第一次烧结，烧结时间为4小时，然后按照10℃/min速率升温至700℃，并通入质量分数为80％的乙醇-水混合物气体200mL，进行第二次烧结后，烧结时间为8h，自然冷却后收集得到K 0.0015Na 0.0015Li 0.997FePO 4材料成品。
二、二次电池的制备
实施例1
1.正极片的制备
将实施例1.1的正极活性材料、导电剂乙炔黑、粘结剂PVDF按重量比95:4:1进行混合，加入溶剂N-甲基吡咯烷酮，充分搅拌混合均匀得到正极浆料，然后涂覆于正极集流体铝箔的两个表面上，其中正极膜片单位面积的涂布重量为0.250g/1540.25mm 2(以不包含溶剂的重量计)，然后烘干、冷压，得到正极片。
2.电解液制备
1M LiPF 6溶解在EC：EMC：DMC＝1：1：1组成的溶液中。
3.负极片的制备
将负极活性物质人造石墨、导电剂乙炔黑、粘结剂SBR+CMC按照重量比95:1.5:3.1:0.4进行混合，加入溶剂去离子水，充分搅拌混合均匀得到负极浆料，然后涂覆于负极集流体铜箔的两个表面上，其中负极膜片单位面积的涂布重量为0.140g/1540.25mm 2(以不包含溶剂的重量计)，经烘干、冷压后得到负极片。
4.隔离膜的制备
以聚乙烯多孔膜作为隔离膜。
5.二次电池的制备
将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入电解液并封装，获得二次电池，并进行性能测试。
实施例2～11的二次电池和对比例1-2的二次电池与实施例1的二次电池制备方法相似，但是调整了电池正极活性材料和电解液的组成，不同的产品参数详见表1。
二、电池性能测试
电池的45℃循环性能测试
在45℃下，将锂离子电池以1C恒流充电至4.45V，然后以4.45V恒压充电至电流小于0.05C，然后将锂离子电池以1C恒流放电至2.8V，得到首次放电容量C0，记为第1次循环。如此反复进行充电和放电，计算锂离子电池放电容量衰减到C0的80％的循环次数。
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1。
表1 各实施例和对比例的电池组成和循环性能
Figure PCTCN2022085791-appb-000001
锂离子电池正极活性材料中掺入钠离子和钾离子，电芯循环性能提升，且随掺杂量增加，电池的循环性能先增加后降低，钠掺杂量在0.025最优。钠离子和钾离子掺杂提高了正极活性材料结构稳定性从而提升电池的循环性能。
实施例1、8、9和对比例1对比可知，包含钠离子的正极活性材料，配合添加钠盐的电解液，可显著提升二次电池的循环性能。电解液中添加钠盐后，正极活性材料中的钠离子可通过电解液嵌入到石墨层中，起到支撑作用，降低锂离子嵌入/脱出而引起膨胀/收缩，从而降低SEI破环，减少活性锂损失，提高电池的循环性能。
实施例8、12和对比例1对比可知，不同电解质盐均可大幅提升电池循环性能。
综上，半径较大的离子掺入正极活性材料中，搭配含该离子盐的电解液，有利于大 幅提升电池的循环性能。一方面半径较大的离子掺起到稳定阴极层状结构作用，降低材质损失。另一方面，半径较大的离子通过含该离子盐的电解液嵌入石墨材料中，支撑石墨层状结构，减少活性锂损失，提高电池的循环性能。
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 (11)

  1. 一种二次电池，包含(1)正极极片，其包括正极集流体以及设置在正极集流体的至少一个表面上且含有正极活性材料的正极膜层；(2)电解液；其特征在于，所述正极活性材料为具有以下化学式的含A、B双阳离子的活性材料
    A xB 1-xMeO 2或A xB 1-xMPO 4，
    其中
    Me选自Mn、Fe、Ni、Co、V、Cu、Cr元素中的一种或多种；
    M选自Mn、Fe、Ni、Co中的一种或多种；
    A为K或Na,
    B为Na或Li；
    其中A的离子半径大于B，并且A与B种类不同；
    x为0.001-0.05；并且
    所述电解液包含A、B双阳离子电解质盐，其中A、B与所述正极活性材料中的定义相同。
  2. 根据权利要求1所述的二次电池，其特征在于，所述电解液中两种所述阳离子的摩尔浓度比大于等于所述正极活性材料中的两种阳离子的化学计量比。
  3. 根据权利要求1或2所述的二次电池，其特征在于，所述双阳离子电解质盐选自锂、钠、钾中的两种或更多种元素的无机盐和有机盐中的至少一种，无机盐选自六氟磷酸盐、高氯酸盐、六氟砷酸盐、四氟硼酸盐、二氟磷酸盐中的至少一种；有机盐选自二草酸硼酸盐、草酸二氟硼酸盐、双氟磺酰亚胺盐、双三氟甲基磺酰亚胺盐中的至少一种。
  4. 根据权利要求1-3中任一项所述的二次电池，其特征在于，所述化学式A xB 1-xMeO 2的正极活性材料选自化学式为A xB 1-xNiO 2、A xB 1-xMnO 2、A xB 1-xCoO 2、A xB 1-xNi yCo zMn 1-y-zO 2、A xB 1-xNi yCo zAl 1-y-zO 2的活性材料及其包覆和掺杂产物中的至少一种；其中所述A、B和x如权利要求1中所定义；0≤z≤1，0≤y≤1。
  5. 根据权利要求1-4中任一项所述的二次电池，其特征在于，所述化学式A xB 1-xMPO 4的正极活性材料选自化学式为A xB 1-xFePO 4、A xB 1-xCoPO 4的活性材料中的至少一种；其中所述A、B和x如权利要求1中所定义。
  6. 一种制备权利要求1-5中任一项所述的二次电池用的正极活性材料的方法，其包 括以下步骤：
    1)提供Me或M过渡金属的前驱体。
    2)将所述前驱体与A金属盐、B金属盐混合均匀，研磨；然后将研磨后的粉末进行煅烧，之后冷却至室温，得到所述正极活性材料；
    其中Me或M、A、B如权利要求1-5中任一项所定义。
  7. 根据权利要求6所述的方法，其特征在于，所述A金属盐、B金属盐为碳酸盐、氢氧化物中的至少一种。
  8. 根据权利要求6或7所述的方法，其特征在于，所述前驱体与A金属盐或B金属盐的摩尔比为其化学计量比的105％-109％。
  9. 一种电池模块，其特征在于，包括权利要求1-5中任一项所述的二次电池。
  10. 一种电池包，其特征在于，包括权利要求9所述的电池模块。
  11. 一种用电装置，其特征在于，包括选自权利要求1-5中任一项所述的二次电池、权利要求9所述的电池模块或权利要求10所述的电池包中的至少一种。
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US20160218363A1 (en) * 2013-09-09 2016-07-28 The Regents Of The University Of California Lithium and sodium containing layered oxide material, cathodes and sodium ion electrochemical cells
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CN101836315A (zh) * 2007-10-25 2010-09-15 丰田自动车株式会社 正极活性物质、锂二次电池及其制造方法
CN104769757A (zh) * 2012-11-08 2015-07-08 丰田自动车株式会社 正极活性物质和混合离子电池
US20160218363A1 (en) * 2013-09-09 2016-07-28 The Regents Of The University Of California Lithium and sodium containing layered oxide material, cathodes and sodium ion electrochemical cells
WO2020102906A1 (fr) * 2018-11-21 2020-05-28 HYDRO-QUéBEC Additifs comprenant des ions métalliques alcalins ou alcalino-terreux et leur utilisation dans les cellules électrochimiques
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