WO2024011541A1 - 二次电池、电池模块、电池包和用电装置 - Google Patents

二次电池、电池模块、电池包和用电装置 Download PDF

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WO2024011541A1
WO2024011541A1 PCT/CN2022/105827 CN2022105827W WO2024011541A1 WO 2024011541 A1 WO2024011541 A1 WO 2024011541A1 CN 2022105827 W CN2022105827 W CN 2022105827W WO 2024011541 A1 WO2024011541 A1 WO 2024011541A1
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carbonate
secondary battery
electrolyte
negative electrode
film layer
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PCT/CN2022/105827
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English (en)
French (fr)
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陈慧玲
韩昌隆
吴则利
郭洁
姜彬
黄磊
张翠平
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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 PCT/CN2022/105827 priority Critical patent/WO2024011541A1/zh
Publication of WO2024011541A1 publication Critical patent/WO2024011541A1/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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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 field of batteries, and specifically to a secondary battery, a battery module, a battery pack and an electrical device.
  • Secondary batteries have the characteristics of high capacity and long life, so they are widely used in electronic equipment, such as mobile phones, laptop computers, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools etc. As the range of battery applications becomes more and more extensive, the performance requirements for secondary batteries are becoming increasingly stringent.
  • This application was made in view of the above-mentioned problems, and its purpose is to provide a secondary battery, a battery module, a battery pack, and an electrical device.
  • a first aspect of the application provides a secondary battery.
  • the secondary battery includes a positive electrode sheet, which includes a positive electrode film layer, a negative electrode sheet, an electrolyte and a solid electrolyte; the negative electrode sheet includes a negative electrode film layer; and a solid electrolyte Disposed on the surface of the positive electrode film layer and/or the negative electrode film layer, the solid electrolyte includes a polymer matrix and a first additive, the first additive is configured to form an interface film on the surface of the positive electrode film layer and/or the negative electrode film layer, wherein polymerization
  • the mass percentage of the material matrix relative to the total mass of the solid electrolyte is recorded as A%; the mass percentage of the first additive relative to the total mass of the solid electrolyte is recorded as B%.
  • the secondary battery satisfies: 0.1 ⁇ B/ A ⁇ 19; optionally, 0.5 ⁇ B/A ⁇ 10.
  • the polymer matrix in the solid electrolyte of the present application has a certain viscosity, thereby adhering the solid electrolyte to the surface of the active material.
  • the solid electrolyte has good thermal stability and chemical stability. It can maintain good cycle stability during the charge and discharge process of the secondary battery and improve the cycle performance of the secondary battery.
  • the solid electrolyte also has a wide stable electrochemical window. The wide stable electrochemical window can ensure that the electrolyte and the positive and negative electrodes are not prone to adverse interface reactions during the charge and discharge process, thus reducing the internal resistance of the secondary battery and reducing heat generation. Improve the safety performance and service life of secondary batteries.
  • the interface film formed by the first additive on the surface of the active material will not be too thick, which is beneficial to the transmission of metal ions, and the impedance of the interface film is low, which is beneficial to improving the dynamic performance of the secondary battery.
  • the combined use of solid electrolytes and liquid electrolytes can take into account the advantages of solid electrolytes and liquid electrolytes, and can improve the kinetic performance, safety performance and cycle performance of secondary batteries.
  • the secondary battery satisfies: 5 ⁇ A ⁇ 99; and/or 0.1 ⁇ B ⁇ 95.
  • the mass percentage of the polymer matrix is within the above range, the adhesive force between the polymer matrix and the active material can be ensured. During the charging and discharging process of the secondary battery, the solid electrolyte will not easily fall off from the surface of the active material.
  • the mass percentage of the first additive is within the above range, it can ensure that the first additive forms a uniform and stable interface film on the positive electrode film layer and/or the negative electrode film layer, and the impedance of the interface film is relatively low, which is beneficial to improving the secondary battery. dynamic properties.
  • the first additive includes: a boron-containing lithium salt, whose mass percentage relative to the total mass of the solid electrolyte is recorded as B1%; a negative electrode film-forming additive, whose mass percentage relative to the total mass of the solid electrolyte is B1%.
  • the component content is recorded as B2%, where the secondary battery satisfies: 0.002 ⁇ B1/B2 ⁇ 10.
  • the secondary battery satisfies: 0.1 ⁇ B1 ⁇ 50; and/or 0.1 ⁇ B2 ⁇ 50.
  • the molecular formula of the boron-containing lithium salt is LiBF a O b C c P d , in the molecular formula, 0 ⁇ a ⁇ 4, 0 ⁇ b ⁇ 8, 0 ⁇ c ⁇ 4, 0 ⁇ d ⁇ 4;
  • the boron-containing lithium salt includes one or more of lithium tetrafluoroborate LiBF 4 , lithium bisoxaloborate LiBOB, and lithium bisfluoroxaloborate LiDFOB.
  • the SEI film formed by the three has more components and the structure of the SEI film is more stable; and On the basis of ensuring structural stability, the SEI film can be guaranteed to have a relatively small resistance value to ensure the low-temperature performance of the secondary battery.
  • the negative electrode film-forming additive includes one or more of carbonate additives, sulfate additives, and sulfite additives.
  • the negative electrode film-forming additive of the present application is combined with the boron-containing lithium salt to form an SEI film on the surface of the negative active material, and multiple components can form a film on the surface of the SEI film to enrich the film structure of the SEI film and improve the SEI. Structural stability of the membrane.
  • the carbonate additives include cyclic carbonate solvents and/or linear carbonate solvents; optionally, the cyclic carbonate solvents include vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate One or more of ethylene carbonate DFEC, vinyl ethylene carbonate VEC and dioctyl carbonate CC; linear carbonate solvents include ethyl allyl carbonate AEC, diphenyl carbonate DPC and methyl allyl carbonate One or more of MAC and polycarbonate VA; and/or sulfate ester additives include cyclic sulfonate ester additives and/or sulfated alkyl ester additives; optionally, cyclic sulfonate ester additives include One or more of 1,3-propane sultone PS, propylene sultone PES, 3-fluoro-1,3-propane sultone FPS; and/or sulfate hydrocarbon ester
  • the electrolyte solution includes: a cyclic carbonate solvent, whose mass percentage relative to the total mass of the electrolyte is recorded as M1%; and a linear carbonate solvent, whose mass content relative to the total mass of the electrolyte is 1%.
  • the component content is recorded as M2%, where the secondary battery satisfies: 10 -3 ⁇ M1/M2 ⁇ 2, the preferred range is 0.1 ⁇ M1/M2 ⁇ 1; optionally, 1 ⁇ M1 ⁇ 20; and/or 50 ⁇ M2 ⁇ 85.
  • the mass percentages of the cyclic carbonate solvent and linear carbonate solvent of the present application are within the above range, the ionic conductivity of the electrolyte can be further improved.
  • the cyclic carbonate solvent includes ethylene carbonate EC, propylene carbonate PC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinyl ethylene carbonate VEC, and One or more of dioctyl carbonate CC; and/or linear carbonate solvents including ethyl allyl carbonate AEC, diphenyl carbonate DPC and methyl allyl carbonate MAC, polycarbonate VA, dicarbonate Ethyl ester DEC, ethyl methyl carbonate EMC, methyl propyl carbonate MPC, ethyl propyl carbonate EPC, methyl butyl carbonate MBC, methyl acetate MA, ethyl acetate EA, methyl propionate MP and ethyl propionate EP of one or more.
  • linear carbonate solvents including ethyl allyl carbonate AEC, diphenyl carbonate DPC and methyl allyl carbonate
  • the electrolyte includes: an electrolyte film-forming additive, whose mass percentage based on the total mass of the electrolyte is denoted as D1%; a lithium salt, whose mass percentage based on the total mass of the electrolyte is denoted as D2%, the secondary battery satisfies: 0.2 ⁇ E/(D1+D2) ⁇ 2.95, where E represents the viscosity of the electrolyte, and its unit is mPa ⁇ s.
  • the secondary battery When the secondary battery satisfies the above formula, it is beneficial to improve the kinetic properties of the electrolyte. For example, when a relatively high content of lithium salt and electrolyte film-forming additives are added, the viscosity of the electrolyte is increased, which is conducive to the coordination of the electrolyte and the solid electrolyte.
  • the electrolyte film-forming additives are easier to pass through the solid electrolyte in the active state. Film formation on the surface of the material. With the combination of the electrolyte and the linear carbonate solvent, the viscosity of the electrolyte can be further adjusted to a relatively low range, which is conducive to the migration of lithium ions and thus ensures the dynamic performance of the electrolyte.
  • the percentage of the solution solid mass content and liquid mass content of the solid electrolyte is recorded as m; the compacted density of the positive electrode film layer is recorded as P1g/cm 3 and the thickness of the positive electrode film layer is recorded as h1 ⁇ m.
  • the secondary battery satisfies: 5 ⁇ h1*P1/m ⁇ 250.
  • the diffusion path of the polymer slurry is moderate, and it cooperates with the polymerization
  • the viscosity of the polymer slurry is conducive to the diffusion of the polymer slurry into the active material, and due to the moderate compaction density, the porosity of the positive electrode membrane layer is moderate, which is conducive to the diffusion of the polymer slurry into the pores of the active material, thus
  • the bonding strength between the solid electrolyte formed by the polymer slurry and the active material can be enhanced, and the impedance at the interface between the solid electrolyte and the active material is relatively low.
  • the percentage of the solution solid mass content and liquid mass content of the solid electrolyte is recorded as m; the compacted density of the negative electrode film layer is recorded as P2g/cm 3 and the thickness of the negative electrode film layer is recorded as h2 ⁇ m.
  • the secondary battery satisfies: 25 ⁇ h2*P2/m ⁇ 245.
  • the porosity of the negative electrode film layer is moderate, which is conducive to the diffusion of the polymer slurry into the pores of the active material, thereby enabling the solid electrolyte formed by the polymer slurry to The bonding strength of the active material is enhanced, and the impedance at the interface between the solid electrolyte and the active material is relatively low.
  • a second aspect of the application also provides a battery module, including the secondary battery according to any embodiment of the first aspect of the application.
  • a third aspect of the present application also provides a battery pack, including the battery module according to the embodiment of the second aspect of the present application.
  • the fourth aspect of the present application also provides an electrical device, including a secondary battery as in any embodiment of the first aspect of the present application, a battery module as in the second embodiment of the present application, or a third embodiment of the present application. battery pack.
  • FIG. 1 is a schematic diagram of an embodiment of the secondary battery of the present application.
  • FIG. 2 is an exploded schematic view of the embodiment of the secondary battery of FIG. 1 .
  • FIG. 3 is a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 4 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of an embodiment of a power consumption device including the secondary battery of the present application as a power source.
  • the reference symbols are as follows: 1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module; 5. Secondary battery; 51. Case; 52. Electrode assembly; 53. Cover; 6 , electrical equipment.
  • 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
  • a 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) can be added to the method in any order.
  • the method may include steps (a), (b) and (c), and may also include step (a). , (c) and (b), and 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).
  • Secondary batteries have the characteristics of high capacity and long life, so they are widely used; with the development of the new energy industry, higher requirements have been put forward for the electrical performance and reliability of secondary batteries.
  • energy density of secondary batteries and battery Capacity has been improved, but safety problems may still occur in secondary batteries.
  • the heat accumulated inside the secondary battery may cause the cathode and anode to contact after the isolation film is damaged, causing severe Burning and other phenomena caused by redox reactions. Due to the safety issues of the liquid electrolyte itself, the development of secondary batteries is restricted, so it is of great significance to develop secondary batteries with higher safety.
  • solid electrolyte was used to perform coating protection treatment on the surface of the pole piece.
  • the solid electrolyte has higher thermal stability and chemical stability than the liquid electrolyte, and because the solid electrolyte is disposed on the surface of the pole piece , even if the isolation membrane is damaged, direct contact between the anode and cathode can be avoided, so it has high safety.
  • solid electrolytes have a wide electrochemical window, which can effectively reduce the generation of interface side reactions and improve the cycle life of secondary batteries. At the same time, they have good electrochemical stability and can match cathode active materials with higher charging voltages. Therefore, it has higher energy density.
  • the interface between the solid electrolyte and the active material is a solid-solid interface.
  • the effective contact between the solid electrolyte and the active material is weak, and the transmission kinetics of metal ions in the solid material is low, resulting in a large interface impedance.
  • the inventor conducted in-depth research on secondary batteries and found that solid electrolytes and electrolytes are used together, and specific substances are added to the solid electrolytes to improve the protective performance of the active materials and reduce the interaction between the solid electrolytes and the active materials.
  • the impedance improves the dynamic performance; and when combined with a relatively low viscosity electrolyte, the dynamic performance of the electrolyte is improved, thereby comprehensively improving the dynamic performance, safety performance and cycle performance of the secondary battery.
  • Secondary batteries also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • the secondary battery includes a positive electrode piece, a negative electrode piece, an electrolyte and a solid electrolyte; the positive electrode piece includes a positive electrode film layer; the negative electrode piece includes a negative electrode film layer; the solid electrolyte is disposed on the positive electrode film layer and the negative electrode film the surface of at least one of the layers, the solid electrolyte including a polymer matrix and a first additive configured to form an interface film on the surface of the positive electrode film layer and/or the negative electrode film layer, wherein, the mass percentage of the polymer matrix relative to the total mass of the solid electrolyte is recorded as A%; the mass percentage of the first additive relative to the total mass of the solid electrolyte is recorded as B %, the secondary battery satisfies: 0.5 ⁇ B/A ⁇ 19.
  • the secondary battery of the present application can comprehensively improve the dynamic performance, safety performance and cycle performance of the secondary battery.
  • the solid electrolyte can be disposed on the positive electrode film layer.
  • the positive electrode film layer includes the positive electrode active material, that is, the solid electrolyte is disposed on the positive electrode active material.
  • the first additive in the solid electrolyte can react with the positive electrode active material to form a film.
  • the positive electrode solid electrolyte interface film CEI film is formed.
  • the solid electrolyte can also be disposed on the negative electrode film layer, that is, the solid electrolyte is disposed on the negative electrode active material.
  • the first additive in the solid electrolyte can react with the negative electrode active material to form a solid electrolyte interface film (Solid) on the surface of the negative electrode active material. Electrolyte Interphase, SEI membrane).
  • the solid electrolyte is provided on the positive electrode film layer and the negative electrode film layer, that is, the solid electrolyte is provided on the positive electrode active material, and the solid electrolyte is provided on the negative electrode active material.
  • CEI film and SEI film are collectively referred to as interface films.
  • the solid electrolyte is arranged on the active material, and the polymer matrix in the solid electrolyte has a certain viscosity, thereby attaching the solid electrolyte to the surface of the active material.
  • the solid electrolyte has good thermal stability and chemical stability. It can maintain good cycle stability during the charge and discharge process of the secondary battery and improve the cycle performance of the secondary battery.
  • the solid electrolyte also has a wide stable electrochemical window. The wide stable electrochemical window can ensure that the electrolyte and the positive and negative electrodes are not prone to adverse interface reactions during the charge and discharge process, thus reducing the internal resistance of the secondary battery and reducing heat generation. Improve the safety performance and service life of secondary batteries.
  • the polymer matrix generally has a porous structure with a small pore size; when the first additive and the polymer matrix form a solid electrolyte, the first additive can be filled in the pores of the polymer matrix, and the first additive is more dispersed in the polymer matrix.
  • the groups in the polymer matrix can complex and coordinate with the metal ions in the first additive, such as lithium ions.
  • the metal ions Along with the irregular Brownian motion process of the polymer matrix, the metal ions repeatedly occur on the polymer matrix. Coordination and decoordination realize the transfer of lithium ions. Since the first additive used for film formation is disposed in the solid electrolyte, the amount of the first additive used is relatively small, which can reduce the moisture content caused by the introduction of the first additive, thereby reducing the risk of side reactions occurring inside the secondary battery. risk.
  • the electrolyte After the electrolyte is injected into the secondary battery, the electrolyte infiltrates the positive electrode piece and the negative electrode piece. Under the infiltration of the electrolyte, the first additive contained in the solid electrolyte can be dissolved in the electrolyte, and the dissolved first additive is more It is easy to form an interface film on the surface of the active material, which has a good protective effect on the active material, and the interface film formed by the first additive on the surface of the active material will not be too thick, which is conducive to the transmission of metal ions, and the impedance of the interface film Lower, which is beneficial to improving the dynamic performance of secondary batteries. In addition, the solid electrolyte can also reduce the risk of side reactions between the solvent in the electrolyte and the positive and negative electrode plates, reducing the possibility of electrolyte decomposition.
  • the kinetic process usually includes the following steps: taking the metal ions as lithium ions as an example, the lithium ions are detached from the positive active material and migrate to the electrolyte phase; the solvated lithium ions in the electrolyte move to Diffusion transfer occurs on the surface of the negative active material; lithium ions obtain electrons from the surface of the negative active material and diffuse into the interior of the negative active material.
  • the kinetic process usually includes the following steps: taking the metal ions as lithium ions as an example, the lithium ions are detached from the positive active material and migrate to the electrolyte phase; the solvated lithium ions in the electrolyte move to Diffusion transfer occurs on the surface of the negative active material; lithium ions obtain electrons from the surface of the negative active material and diffuse into the interior of the negative active material.
  • the CEI film on the surface of the positive active material is thin, its migration barrier is relatively low; since the electrolyte is a liquid electrolyte, its viscosity is relatively low.
  • the ionic conductivity is high, so when lithium ions migrate from the electrolyte to the negative active material, the migration barrier is relatively low; because the SEI film on the surface of the negative active material is thin, lithium ions migrate from the SEI film to the negative active material.
  • the internal migration barrier is also relatively low. Therefore, the migration barrier of lithium ions in the entire dynamic process is low and requires less energy, which is conducive to the rapid migration of lithium ions, thereby improving the dynamic performance of the secondary battery. Relatively good.
  • This application uses a solid electrolyte and a liquid electrolyte together, which can take into account the advantages of the solid electrolyte and the liquid electrolyte, and can improve the kinetic performance, safety performance and cycle performance of the secondary battery.
  • the solid electrolyte includes a polymer matrix and a first additive.
  • the polymer matrix includes polyethylene oxide PEO, polyurethane PU, polymethyl methacrylate PMMA, polyacrylonitrile PAN, polyvinylidene fluoride PVDF, poly(vinylidene fluoride-hexafluoropropylene) P (VDF-HFP), polypropylene carbonate PPC and polycarbonate PC, polyvinyl chloride PVC, polyvinyl carbonate PEC, polylactic acid PLA, polytetrafluoroethylene PTFE and blends and copolymers containing characteristic functional groups One or more, the characteristic functional groups include electron-withdrawing groups.
  • Blends adjust the physical and chemical properties of materials, such as PVDF-HFP/polyethyl methacrylate PEMA, PEO/PVDF, PVDF-HFP/polyvinyl acetate PVAc, PVC/PMMA, PVDF-HFP/PMMA , PVDF-HFP/PAN and other blending systems; copolymer systems include PEO-polystyrene PSt, polydimethylsiloxane (PDMS)-PEO, PEGMA-MMA-IBVE, PEO-PMMA, POEM-PBMA , PPG-PEG-PPG, MMA-AN-BA, etc.
  • PEMA polyethyl methacrylate
  • PEO/PVDF PVDF-HFP/polyvinyl acetate PVAc
  • PVC/PMMA polydimethylsiloxane
  • PEO-PMMA polydimethylsiloxane
  • POEM-PBMA PPG-PEG-PPG
  • the above-mentioned polymer matrix has good mechanical properties, and the solid electrolyte formed has good flexibility, and can form a stable and good electrode electrolyte interface with the active material; in addition, the molecular chain segments of the above-mentioned polymer matrix polymer have the ability to move thermally , and as the temperature increases, the thermal motion of the molecular chain segments intensifies, and the polymer matrix has the ability to conduct lithium ions, which is conducive to the continuous coordination-dissociation-coordination of metal ions such as lithium ions with characteristic atoms and groups.
  • the process realizes the transmission of lithium ions within or between molecular chains of the polymer matrix, so that the formed solid electrolyte has high ionic conductivity.
  • the mass percentage content A% of the polymer matrix is: 5 ⁇ A ⁇ 99.
  • the mass percentage of the polymer matrix is within the above range, the adhesive force between the polymer matrix and the active material can be ensured. During the charging and discharging process of the secondary battery, the solid electrolyte will not easily fall off from the surface of the active material.
  • 5 ⁇ A ⁇ 70 for example, the mass percentage A% of the polymer matrix can be 5%, 10%, 15%, 25%, 35%, 45%, 55%, 65%, 70%, 90%, 95% or 99%; or a range consisting of any two of the above values.
  • the first additive may be used to form an interface film on the surface of the positive electrode film layer and/or the negative electrode film layer. Based on the total mass of the solid electrolyte, the mass percentage B% of the first additive is: 0.1 ⁇ B ⁇ 95.
  • the mass percentage of the first additive When the mass percentage of the first additive is within the above range, it can ensure that the first additive forms a uniform and stable interface film on the positive electrode film layer and/or the negative electrode film layer, and the impedance of the interface film is relatively low, which is beneficial to improving the secondary battery. dynamic properties.
  • 10 ⁇ B ⁇ 95 for example, the mass percentage B% of the first additive can be 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 95%; or a range consisting of any two of the above values.
  • the first additive may include a conductive lithium salt to ensure smooth migration of lithium ions.
  • the conductive lithium salt can be a boron-containing lithium salt. Boron-containing lithium salts have good compatibility with the polymer matrix, and the addition of boron-containing lithium salts can reduce the glass transition temperature of the polymer matrix to a certain extent, improve the mechanical strength of the polymer matrix and the stability temperature of the amorphous phase. .
  • the boron-containing lithium salt has a larger anionic group and can easily dissociate lithium ions, thus ensuring the solubility of lithium ions and improving the ionic conductivity of the polymer electrolyte.
  • the molecular formula of the boron-containing lithium salt is LiBF a O b C c P d , and in the molecular formula, 0 ⁇ a ⁇ 4, 0 ⁇ b ⁇ 8, 0 ⁇ c ⁇ 4, 0 ⁇ d ⁇ 4.
  • B atoms can be combined with oxygen-containing oxalic acid ligands.
  • the combined product has excellent thermal stability and is easy to form an SEI film with excellent performance on the surface of the negative active material, thus ensuring the structural stability of the negative active material. This further improves the cycle performance of the secondary battery.
  • B atoms can also be combined with halogen atoms, especially fluorine atoms.
  • the electron-withdrawing induction effect of fluorine atoms is strong, its thermal stability and chemical stability are high, and the solubility of lithium ions in the electrolyte is high, which can ensure The solubility of lithium ions ensures the conductivity of the electrolyte.
  • boron-containing lithium salts include lithium tetrafluoroborate (LiBF 4 ), lithium bisoxaloborate (LiB(C 2 O 4 ) 2 , LiBOB), and lithium bisfluoroborate borate (LiBC 2 O 4 F 2 , LiDFOB ) one or more.
  • boron-containing lithium salts include lithium tetrafluoroborate LiBF 4 , lithium bisoxaloborate (LiB(C 2 O 4 ) 2 , referred to as LiBOB) and lithium difluoroborate borate (LiBC 2 O 4 F 2 , referred to as LiDFOB). combination.
  • lithium tetrafluoroborate LiBF 4
  • organic solvents such as carbonate solvents or additives in the electrolyte
  • the viscosity of the system composed of lithium tetrafluoroborate is relatively low, which is conducive to the release of lithium ions, thus making The conductivity in the electrolyte is increased.
  • the thickness of the SEI film formed by lithium tetrafluoroborate is relatively uniform, the kinetic activity is good, and the charge transfer resistance in the secondary battery is small, which can significantly improve the low-temperature performance of the secondary battery; the SEI film is not prone to thermal decomposition. Its performance at high temperatures is relatively stable, so it can significantly improve the high-temperature performance of secondary batteries.
  • Either lithium bisoxalatoborate LiBOB or lithium bisfluoroxaloborate LiDFOB has a passivating effect on the positive electrode current collector in the positive electrode piece, which can reduce the risk of side reactions with the positive electrode current collector to corrode the positive electrode current collector, and improve the performance of the positive electrode. Structural stability of pole pieces.
  • the electrolyte containing either lithium bisoxaloborate LiBOB or lithium bisfluoroxaloborate LiDFOB is less likely to generate acidic substances and can further reduce the risk of corrosion of the positive electrode current collector.
  • Lithium bisoxaloborate LiBOB and lithium bisfluoroxaloborate LiDFOB have good compatibility with the positive active material and are conducive to the migration of lithium ions; they can form an effective SEI film on the surface of the negative active material, improving the resistance to the negative active material. Protective properties.
  • Lithium tetrafluoroborate LiBF 4 , lithium bisoxaloborate LiBOB and lithium bisfluoroxaloborate LiDFOB are used together.
  • the SEI film formed by the three has more components, and the structure of the SEI film is more stable; and on the basis of ensuring structural stability On the other hand, the SEI film can be guaranteed to have a relatively small resistance value to ensure the low-temperature performance of the secondary battery.
  • the mass percentage of the boron-containing lithium salt is recorded as B1%, and 0.1 ⁇ B1 ⁇ 50.
  • the mass percentage of the boron-containing lithium salt When the mass percentage of the boron-containing lithium salt is within the above range, it can ensure the ion conduction ability of the solid electrolyte; it can also play a good protective role in the positive electrode current collector and can play a good protective role in the negative electrode active material.
  • the mass percentage B1% of the boron-containing lithium salt can be 0.1%, 0.5%, 1%, 2%, 10%, 20%, 25% or 50%, etc.
  • the conductive lithium salt may also include an ion-conducting lithium salt, and the ion-conducting lithium salt includes lithium hexafluorophosphate LiPF 6 , lithium difluorophosphate LiPO 2 F 2 , lithium difluorobisoxalate phosphate LiDODFP, lithium tetrafluorooxalate phosphate LiDFBP, Lithium bisfluorosulfonimide LiFSI, lithium bistrifluoromethylsulfonimide LiTFSI, lithium fluorosulfonate LiSO 3 F, lithium nitrate LiNO 3 , lithium perchlorate LiClO 4 , lithium hexafluoroantimonate LiSbF 6 , One or more of lithium hexafluoroarsenate LiAsF 6 .
  • the above-mentioned ion-conducting lithium salt has a relatively high degree of dissociation and high conductivity, which is conducive to the migration of lithium ions.
  • the first additive may include a negative electrode film-forming additive
  • the negative electrode film-forming additive includes one or more of carbonate additives, sulfate additives, and sulfite additives.
  • the negative electrode film-forming additive and the boron-containing lithium salt are combined to form an SEI film on the surface of the negative electrode active material, and multiple components can form a film on the surface of the SEI film to enrich the film structure of the SEI film and improve the structure of the SEI film. stability.
  • the negative electrode film-forming additives include at least two of carbonate additives, sulfate additives, sulfite additives and lithium fluoroxalate phosphate; the SEI film formed by it has a rich composition and a stable structure. Sex is higher.
  • the mass percentage of the negative electrode film-forming additive is recorded as B2%, 0.1 ⁇ B2 ⁇ 50.
  • the mass percentage of the negative electrode film-forming additive is within the above range, it can ensure that the negative electrode film-forming additive forms a uniform and stable SEI film, further improving the protective performance of the negative electrode active material.
  • the mass percentage B2% of the negative electrode film-forming additive can be 0.1%, 0.5%, 1%, 2%, 10%, 20%, 25% or 50%, etc.
  • B1/B2 can be 0.002, 0.2, 0.5, 1, 2, 5 or 9, etc.
  • carbonate additives include cyclic carbonate additives and/or linear carbonate additives.
  • the cyclic carbonate additive includes one of vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinyl ethylene carbonate VEC and dioctyl carbonate CC or Various.
  • the linear carbonate additives include one or more of ethyl allyl carbonate AEC, diphenyl carbonate DPC, methyl allyl carbonate MAC and polycarbonate VA.
  • sulfate ester additives include cyclic sulfonate ester additives and/or sulfate hydrocarbyl ester additives.
  • the cyclic sulfonate additives include one of 1,3-propane sultone PS, propylene sultone PES, 3-fluoro-1,3-propane sultone FPS or Various.
  • the hydrocarbyl sulfate additives include one or more of vinyl sulfate DTD, diethyl sulfate DES and dimethyl sulfate DMS.
  • the sulfite additives include vinyl sulfite ES and/or vinyl vinyl sulfite VES.
  • the solid electrolyte may also include solvents, such as acetonitrile, tetrahydrofuran, acetone, N-methylpyrrolidone, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, acetone, N-methylpyrrolidone, N , at least one of N-dimethylformamide to increase the compatibility between the polymer matrix and the first additive and the like.
  • solvents such as acetonitrile, tetrahydrofuran, acetone, N-methylpyrrolidone, N, at least one of N-dimethylformamide to increase the compatibility between the polymer matrix and the first additive and the like.
  • the solid electrolyte may also include auxiliaries, such as plasticizers, ionic liquids, etc., to improve the ionic conductivity and lithium ion migration number of the solid electrolyte, and to improve the interfacial compatibility of the electrode-electrolyte interface.
  • the plasticizer may be ethylene carbonate EC, propylene carbonate PC, etc.
  • the following method can be used to prepare the solid electrolyte: the polymer matrix, the first additive, etc. are mixed evenly to form a polymer slurry, and the solution casting method is used to apply and transfer it to the surface of the pole piece, and solidify to form a film.
  • the electrolyte plays a role in conducting metal ions between the positive electrode piece and the negative electrode piece.
  • the electrolyte solution in this application can be an electrolyte solution known in the art for secondary batteries.
  • the electrolyte includes lithium salt and organic solvent.
  • the lithium salt can be selected from the group consisting of lithium hexafluorophosphate LiPF 6 , lithium difluorophosphate LiPO 2 F 2 , lithium difluorobisoxalate phosphate LiDODFP, lithium tetrafluorooxalate phosphate LiDFBP, lithium bisfluorosulfonyl imide salt LiFSI, One of lithium trifluoromethylsulfonyl imide LiTFSI, lithium fluorosulfonate LiSO 3 F, lithium nitrate LiNO 3 , lithium perchlorate LiClO 4 , lithium hexafluoroantimonate LiSbF 6 and lithium hexafluoroarsenate LiAsF 6 or at least one of a variety. Based on the total mass of the electrolyte, the mass percentage of lithium salt is recorded as D2%.
  • the lithium salt within the above range can ensure that the electrolyte provides sufficient lithium source to form an ion path, and at the same time makes the electrolyte have high ionic conductivity.
  • D2 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 19, 20, 21, 22, 23 or 25; or any two of the above A range of values.
  • the organic solvent may include carbonate solvents; carbonate solvents include cyclic carbonate solvents and linear carbonate solvents.
  • carbonate solvents include cyclic carbonate solvents and linear carbonate solvents.
  • the combination of cyclic carbonate solvent and linear carbonate solvent makes the electrolyte have high dielectric constant and low viscosity, which can improve the ionic conductivity of the electrolyte; and the electrolyte has high electrochemical stability and the electrochemical window is obtained Significant improvement.
  • the mass percentage of the cyclic carbonate solvent relative to the total mass of the electrolyte is marked as M1%, and the mass percentage of the linear carbonate solvent relative to the total mass of the electrolyte is marked as M2%, 10 -3 ⁇ M1/M2 ⁇ 2.
  • the mass percentage of the cyclic carbonate solvent and the linear carbonate solvent is within the above range, the ionic conductivity of the electrolyte can be further improved.
  • M1/M2 can be 0.001, 0.01, 0.1, 0.2, 0.5, 0.7, 0.9 or 1; or a range consisting of any two of the above values.
  • the cyclic carbonate solvent includes ethylene carbonate EC, propylene carbonate PC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinyl ethylene carbonate VEC and carbonic acid One or more of the dioctyl ester CC.
  • M1 can be 1, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20; or a range consisting of any two of the above values.
  • the linear carbonate solvents include ethyl allyl carbonate AEC, diphenyl carbonate DPC and methyl allyl carbonate MAC, polycarbonate VA, diethyl carbonate DEC, ethyl methyl carbonate EMC, carbonic acid One or more of methyl propyl ester MPC, ethyl propyl carbonate EPC, methyl butyl carbonate MBC, methyl acetate MA, ethyl acetate EA, methyl propionate MP and ethyl propionate EP.
  • M2 may be 50, 52, 55, 56, 58, 60, 62, 65, 66, 68, or 85.
  • the organic solvent may also include ether solvents. Due to their lower viscosity, ether solvents can make the electrolyte have higher ionic conductivity, allowing the lithium ions in the electrolyte to maintain good stability during circulation. Morphology. Exemplarily, ether solvents include diethyl ether, polymethoxy ether, etc.
  • the organic solvent may also include nitrile solvents.
  • Nitrile solvents have higher stability, thereby improving the overall stability of the electrolyte.
  • nitrile solvents may include adiponitrile, glutaronitrile, and the like.
  • organic solvents may also include other types of solvents, such as sulfone solvents.
  • the organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, and butylene carbonate.
  • Ester fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, At least one of 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally further includes electrolyte additives.
  • electrolyte additives may include electrolyte film-forming additives such as negative electrode film-forming additives and positive electrode film-forming additives. They may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, and improve the high-temperature or low-temperature performance of the battery. Additives etc.
  • the negative electrode film-forming additive includes one or more of carbonate additives, sulfate additives and sulfite additives. The specific types of electrolyte film-forming additives are as described in Solid Electrolyte and will not be described again here. Based on the total mass of the electrolyte, the mass percentage of the electrolyte film-forming additive is recorded as D1%.
  • D1 is within the above range, it can ensure that the interface film is fully formed on the surface of the active material to improve the protective effect on the active material.
  • 0.1 ⁇ D1 ⁇ 10 for example, D1 can be 10 -3 , 10 -2 , 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; or It is a range consisting of any two values mentioned above.
  • the secondary battery also satisfies: 0.2 ⁇ E/(D2+D1) ⁇ 2.95; in the formula, E represents the viscosity of the electrolyte, and its unit is mPa ⁇ s.
  • the secondary battery When the secondary battery satisfies the above formula, it is beneficial to improve the kinetic properties of the electrolyte. For example, when a relatively high content of lithium salt and electrolyte film-forming additives are added, the viscosity of the electrolyte is increased, which is conducive to the coordination of the electrolyte and the solid electrolyte.
  • the electrolyte film-forming additives are easier to pass through the solid electrolyte in the active state. Film formation on the surface of the material.
  • the viscosity of the electrolyte can be further adjusted to a relatively low range, which is conducive to the migration of lithium ions and thus ensures the dynamic performance of the electrolyte.
  • E/(D2+D1) can be 0.2, 0.25, 0.28, 1, 1.2, 1.5, 1.8, 2, 2.5 or 2.95; or a range consisting of any two of the above values.
  • E can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7 or 8; or it can be composed of any two of the above values range.
  • the viscosity of the electrolyte can be adjusted within a suitable range, which is beneficial to the migration of lithium ions.
  • 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 current collector has two surfaces facing each other in its 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 solid electrolyte is disposed on the surface of the cathode film layer, that is, on the surface of the cathode film layer facing away from the cathode current collector, which can play a good protective role for the cathode plate, thereby ensuring that the cathode plate Structural stability and improved cycle performance of secondary batteries.
  • the solution solid mass and liquid mass percentage of the solid electrolyte are recorded as m; the compacted density of the positive electrode film layer is recorded as P1g/cm 3 ; the thickness of the positive electrode film layer is recorded as h1 ⁇ m; secondary battery Satisfy: 5 ⁇ h1*P1/m ⁇ 250.
  • the solid materials in the solid electrolyte include polymer matrix, boron-containing lithium salt, etc., and their mass percentage relative to the solid electrolyte is the solution solid mass content of the solid electrolyte.
  • the mass percentage of liquid substances in the solid electrolyte, such as solvents, relative to the solid electrolyte is the liquid mass content of the solid electrolyte.
  • the percentage of solution solid mass content and liquid mass content is m.
  • the compacted density of a material has a well-known meaning in the art, and can be tested using instruments and methods known in the art.
  • An exemplary test method is as follows: weigh 1g of material, add it to a mold with a base area of 1.327cm2 , pressurize it to 2000kg (equivalent to 20000N), maintain the pressure for 30s, then release the pressure, maintain it for 10s, then record and calculate the material's Compaction density under 20000N force.
  • the polymer slurry can well cover the active material and play an interface protection role.
  • the diffusion path of the polymer slurry is moderate, and it cooperates with the polymer slurry.
  • the viscosity is conducive to the diffusion of the polymer slurry into the active material, and due to the moderate compaction density, the porosity of the positive electrode membrane layer is moderate, which is conducive to the diffusion of the polymer slurry into the pores of the active material, thereby enabling polymerization
  • the bonding strength between the solid electrolyte and the active material formed by the slurry is enhanced, and the impedance at the interface between the solid electrolyte and the active material is relatively low.
  • 100 ⁇ h1 ⁇ P1/m ⁇ 250 for example, h1*P1/m can be 0.4, 0.8, 1, 2, 3, 5, 8, 10, 15, 20, 25, 30, 35 , 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100, 110, 120, 150, 160, 170, 180, 190, 200, 220, 250, 260, 280 or 300 ; Or a range consisting of any two of the above values.
  • m can be 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50; or a range consisting of any two of the above values.
  • h1 can be 10, 20, 50, 60, 80, 100, 120, 150, 180, 200, 220, 250, 280, 300; or a range consisting of any two of the above values.
  • P1 can be 0.1, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 or 5; or a range consisting of any two of the above values.
  • the cathode film layer includes a cathode active material
  • the cathode active material may be a cathode active material known in the art for secondary batteries.
  • the cathode active material may include at least one of a lithium transition metal oxide, an olivine-structured lithium-containing phosphate, and their respective modified compounds.
  • lithium transition metal oxides may include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium At least one of nickel cobalt aluminum oxides and their respective modified compounds.
  • lithium-containing phosphates with an olivine structure may include lithium iron phosphate, composites of lithium iron phosphate and carbon, lithium manganese phosphate, composites of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon. At least one of the composite materials and their respective modifying compounds.
  • the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for secondary 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.
  • the positive active material includes LiN _ Any one of Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, and 0 ⁇ y ⁇ 1, 0 ⁇ x ⁇ 1, 0 ⁇ z ⁇ 1, x+y+z ⁇ 1, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, a+b+c ⁇ 1.
  • the positive active material is used in conjunction with the boron-containing lithium salt.
  • the B atoms in the boron-containing lithium salt are easily combined with the O atoms in the positive active material, thereby reducing the charge transfer resistance of the positive active material and reducing the concentration of lithium ions in the bulk phase of the positive active material. diffusion resistance.
  • the low-cobalt or cobalt-free cathode active material can have a significantly improved lithium ion diffusion rate.
  • the low-cobalt or cobalt-free cathode active material Lithium ions in the bulk phase can be replenished to the surface in a timely manner to avoid excessive delithiation on the surface of low-cobalt or cobalt-free cathode active materials, thereby stabilizing the crystal structure of low-cobalt or cobalt-free cathode active materials.
  • the crystal structure of the low-cobalt or cobalt-free cathode active material is more stable, it can greatly reduce the change in structural properties, chemical properties or electrochemical properties of the cathode active material due to excessive delithiation on the surface of the low-cobalt or cobalt-free cathode active material.
  • the probability of problems such as instability, for example, irreversible distortion of the cathode active material and increased lattice defects.
  • LiN x Co y Mn z M 1-xyz O 2 or LiN a Co b Al c N 1-abc O 2 can be prepared according to conventional methods in the art.
  • An exemplary preparation method is as follows: a lithium source, a nickel source, a cobalt source, a manganese source, an aluminum source, an M element precursor, and an N element precursor are mixed and then sintered.
  • the sintering atmosphere may be an oxygen-containing atmosphere, such as an air atmosphere or an oxygen atmosphere.
  • the O2 concentration of the sintering atmosphere is, for example, 70% to 100%.
  • the sintering temperature and sintering time can be adjusted according to actual conditions.
  • lithium sources include, but are not limited to, lithium oxide (Li 2 O), lithium phosphate (Li 3 PO 4 ), lithium dihydrogen phosphate (LiH 2 PO 4 ), lithium acetate (CH 3 COOLi), lithium hydroxide (LiOH ), at least one of lithium carbonate (Li 2 CO 3 ) and lithium nitrate (LiNO 3 ).
  • the nickel source includes, but is not limited to, at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, and nickel acetate.
  • the cobalt source includes, but is not limited to, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, and cobalt acetate.
  • the manganese source includes, but is not limited to, at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.
  • the aluminum source includes, but is not limited to, at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum oxalate, and aluminum acetate.
  • the M element precursor includes, but is not limited to, at least one of an oxide of the M element, a nitric acid compound, a carbonic acid compound, a hydroxide compound, and an acetic acid compound.
  • precursors of the N element include, but are not limited to, ammonium fluoride, lithium fluoride, hydrogen fluoride, ammonium chloride, lithium chloride, hydrogen chloride, ammonium nitrate, ammonium nitrite, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, phosphoric acid , at least one of ammonium sulfate, ammonium bisulfate, ammonium bisulfite, ammonium sulfite, ammonium bisulfide, hydrogen sulfide, lithium sulfide, ammonium sulfide and elemental sulfur.
  • the mass percentage of the layered material with the molecular formula LiNixCoyMnzM1 -xyzO2 or LiNiaCobAlcN1 - abcO2 Content is 80% to 99%.
  • the mass percentage of the layered material with the molecular formula LiN 99%, 95% to 99%, 80% to 98%, 85% to 98%, 90% to 98%, 95% to 98%, 80% to 97%, 85% to 97%, 90% to 97% Or 95% to 97%.
  • the positive electrode film layer optionally further includes a positive electrode conductive agent.
  • a positive electrode conductive agent includes superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon.
  • the mass percentage of the cathode conductive agent is less than 5%.
  • the positive electrode film layer optionally further includes a positive electrode binder.
  • the positive electrode binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene One or more combinations of terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the mass percentage of the cathode binder is less than 5% based on the total mass of the cathode film layer.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil or aluminum alloy foil can be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver. and a combination of one or more silver alloys.
  • the polymer material base layer may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate ( One or a combination of one or more of PBT), polystyrene (PS) and polyethylene (PE).
  • the positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing.
  • the cathode slurry is usually formed by dispersing the cathode active material, optional conductive agent, optional binder and any other components in a solvent and stirring evenly.
  • the solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
  • the electrolyte solution of the present application can be prepared according to conventional methods in this field.
  • additives, solvents, electrolyte salts, etc. can be mixed uniformly to obtain an electrolyte solution.
  • the order of adding each material is not particularly limited.
  • additives, electrolyte salts, etc. can be added to the non-aqueous solvent and mixed evenly to obtain a non-aqueous electrolyte.
  • each component and its content in the electrolyte can be determined according to methods known in the art. For example, it can be measured by gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), nuclear magnetic resonance spectroscopy (NMR), or the like.
  • GC-MS gas chromatography-mass spectrometry
  • IC ion chromatography
  • LC liquid chromatography
  • NMR nuclear magnetic resonance spectroscopy
  • An exemplary method of obtaining electrolyte from a secondary battery includes the following steps: discharging the secondary battery to the discharge cut-off voltage (for safety reasons, the battery is generally in a fully discharged state), then centrifuging, and then centrifuging an appropriate amount to obtain The liquid is the non-aqueous electrolyte.
  • the non-aqueous electrolyte can also be obtained directly from the liquid filling port of the secondary battery.
  • 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 solid electrolyte is disposed on the surface of the negative electrode film layer, that is, on the surface of the negative electrode film layer facing away from the negative electrode current collector, which can play a good protective role for the negative electrode sheet, thereby ensuring that the negative electrode sheet Structural stability and improved cycle performance of secondary batteries.
  • the percentage of the solution solid mass content and liquid mass content of the solid electrolyte is recorded as m; the compacted density of the negative electrode film layer under a force of 20000N is recorded as P2g/cm 3 ; The thickness is recorded as h2 ⁇ m; the secondary battery satisfies: 25 ⁇ h2 ⁇ P2/m ⁇ 245.
  • the polymer slurry can well coat the active material, and the diffusion path of the polymer slurry is moderate. It cooperates with the viscosity of the polymer slurry to facilitate the transfer of the polymer slurry to the active material.
  • the porosity of the negative electrode film layer is moderate, which is conducive to the diffusion of the polymer slurry into the pores of the active material, thereby enabling the solid electrolyte and active material formed by the polymer slurry to The bonding strength is enhanced, and the impedance at the interface between the solid electrolyte and the active material is relatively low.
  • h2*P2/m can be 0.04, 0.08, 0.1, 0.2, 0.3, 0.4, 0.8, 1, 2, 3, 5, 8, 10 ,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90,100,110,120,150,160,170,180,190 or 200 ; Or a range consisting of any two of the above values.
  • m can be 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 or a range consisting of any two of the above values.
  • h2 can be 10, 20, 50, 60, 80, 100, 120, 150, 180, 200, 220, 250, 280, 300; or a range consisting of any two of the above values.
  • P2 can be 1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 or 5; or a range consisting of any two of the above values.
  • 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, lithium aluminum alloy, 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 negative electrode film layer optionally further includes a negative electrode binder.
  • the negative electrode binder may include styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, polyacrylic acid).
  • SBR styrene-butadiene rubber
  • SR-1B water-soluble unsaturated resin
  • acrylic resin for example, polyacrylic acid.
  • PAA poly(methacrylate PMAA), poly(sodium acrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS). combination of species.
  • PAA poly(methacrylate PMAA)
  • PAAS poly(sodium acrylate PAAS)
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • CMCS carboxymethyl chitosan
  • the mass percentage of the negative electrode binder is less than 5%.
  • the negative electrode film layer optionally further includes a negative electrode conductive agent.
  • a negative electrode conductive agent can include selected from the group consisting of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and One or a combination of carbon nanofibers.
  • the mass percentage of the negative electrode conductive agent is less than 5%.
  • the negative electrode film layer optionally includes other additives.
  • other auxiliaries may include thickeners, such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, and the like.
  • CMC-Na sodium carboxymethylcellulose
  • PTC thermistor materials such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, and the like.
  • the mass percentage of other additives is less than 2%.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil or copper alloy foil can be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver. and a combination of one or more silver alloys.
  • the polymer material base layer may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate ( One or a combination of one or more of PBT), polystyrene (PS) and polyethylene (PE).
  • the negative electrode film layer is usually formed by coating the negative electrode slurry on the negative electrode current collector, drying and cold pressing.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring evenly.
  • the solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
  • the negative electrode plate does not exclude other additional functional layers besides the negative electrode film layer.
  • the negative electrode sheet further includes a protective layer covering the surface of the negative electrode film layer.
  • the mass percentage of a substance can be measured according to methods known in the art. For example, it can be measured by gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), nuclear magnetic resonance spectroscopy (NMR), or the like.
  • GC-MS gas chromatography-mass spectrometry
  • IC ion chromatography
  • LC liquid chromatography
  • NMR nuclear magnetic resonance spectroscopy
  • 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 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.
  • This application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or any other shape. As shown in FIG. 1 , a square-structured secondary battery 5 is shown 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 is used to 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 can be adjusted according to needs.
  • the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte may be assembled to form a secondary battery.
  • the positive electrode sheet, isolation film, and negative electrode sheet can be formed into an electrode assembly through a winding process or a lamination process.
  • the electrode assembly is placed in an outer package, dried, and then injected with electrolyte. After vacuum packaging, standing, and Through processes such as formation and shaping, secondary batteries are obtained.
  • the secondary batteries according to the present application can be assembled into a battery module.
  • the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 3 is a schematic diagram of the 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, and the number of battery modules contained in the battery pack can be adjusted 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 arranged in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 is used to cover 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 provides an electrical device.
  • the electrical device includes at least one of a secondary battery, a battery module and a battery pack of the present application.
  • Secondary batteries, battery modules and battery packs can be used as power sources for power-consuming devices, and can also be used as energy storage units for power-consuming devices.
  • Electric devices can be, but are not limited to, 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 balls). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the electrical device can select secondary batteries, battery modules or battery packs according to its usage requirements.
  • FIG. 6 is a schematic diagram of an electrical device as an example.
  • the electric device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack 1 or a battery module can be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the electrical device is usually required to be light and thin, and secondary batteries can be used as power sources.
  • An aluminum foil with a thickness of 12 ⁇ m was used as the positive electrode current collector.
  • a copper foil with a thickness of 8 ⁇ m was used as the negative electrode current collector.
  • the polymer matrix P (VDF-HFP), boron-containing lithium salt (LiBF 4 ) and lithium salt LiTFSI are coated on the negative electrode film layer after vacuum defoaming, and at 5°C to 35°C, 0.1% to 30% Place it in a humidity environment for 12 hours to solidify to form a solid electrolyte.
  • a porous polyethylene (PE) film is used as the isolation membrane.
  • the above-mentioned positive electrode piece, isolation film and negative electrode piece in order so that the isolation film is between the positive electrode piece and the negative electrode piece to play an isolation role, and then wind it to obtain the electrode assembly; place the electrode assembly in the outer packaging shell After drying, the electrolyte is injected, and through processes such as vacuum packaging, standing, formation, and shaping, a lithium-ion battery is obtained.
  • Example 2-1 to 2-12 The secondary batteries of Examples 2-1 to 2-12 are prepared in a manner similar to Example 1. The difference from Example 1 is that Examples 2-1 to 2-12 adjust the first additive and The mass percentage of the polymer matrix.
  • Comparative Example 1 and Comparative Example 2 were prepared in a manner similar to Example 1. The difference from Example 1 is that Comparative Example 1 and Comparative Example 2 adjusted the mass percentage of the first additive and the polymer matrix. .
  • the data of Example 1, Example 2 and Comparative Example are shown in Table 1.
  • Example 3-1 to 3-5 The secondary batteries of Examples 3-1 to 3-5 were prepared in a manner similar to Example 1. The difference from Example 1 is that the boron-containing lithium salt was adjusted in Examples 3-1 to 3-5. The mass percentage content is B1%. The data of Example 1 and Example 3 are shown in Table 2.
  • Example 4-7 The secondary batteries of Examples 4-1 to 4-7 were prepared in a manner similar to Example 1. The difference from Example 1 is that the electrolyte film formation was adjusted in Examples 4-1 to 4-7. The mass percentage of additives is D1%. The data of Example 1 and Example 4 are shown in Table 3.
  • Example 5-1 to 5-8 The secondary batteries of Examples 5-1 to 5-8 were prepared in a manner similar to Example 1. The difference from Example 1 is that Examples 5-1 to 5-8 adjusted the thickness of the positive electrode film layer. Compaction density P1 and other parameters. The data of Example 1 and Example 5 are shown in Table 4.
  • Example 6-1 to 6-6 were prepared in a manner similar to Example 1. The difference from Example 1 is that Examples 6-1 to 6-6 adjusted the thickness of the negative electrode film layer. Compaction density P2 and other parameters. The data of Example 6-1 to Example 6-6 are shown in Table 5.
  • each of the above tests can be performed on at least 3 parallel samples and the average value is taken as the test result.
  • 25°C DCR test First conduct a capacity test. The specific operation process is to use a constant current charge and discharge tester to let the secondary battery stand at 25°C for 2 hours, charge it to 4.4V at a rate of 0.33C, and then charge it to a constant voltage until the current is reached. Less than 0.05C; let it stand for 5 minutes, then discharge to 2.8V and record the discharge capacity at this time as the initial capacity of the secondary battery. Then adjust the remaining battery power (expressed in SOC, the formula is remaining power/initial power ⁇ 100%), and test DCR.
  • the performance of the secondary battery can be adjusted by adjusting the mass percentage ratio of the boron-containing lithium salt in the first additive and the negative electrode film-forming additive, especially when 0.002 ⁇ B1/B2 ⁇ 10, the secondary battery The cycle performance and kinetic performance of the battery can be significantly improved.
  • the performance of the secondary battery can be adjusted by adjusting the correlation between the mass percentage of the electrolyte film-forming additive and the lithium salt in the electrolyte and the viscosity of the electrolyte, especially 0.2 ⁇ E/(D1+ When D2) ⁇ 2.95, the cycle performance and kinetic performance of the secondary battery can be significantly improved.

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Abstract

本申请提供了一种二次电池、电池模块、电池包和用电装置。所述二次电池包括正极极片，其包括正极膜层、负极极片、电解液和固态电解质；负极极片包括负极膜层；固态电解质设置于正极膜层和/或负极膜层的表面，固态电解质包括聚合物基质和第一添加剂，第一添加剂被配置为在正极膜层和/或负极膜层的表面形成界面膜，其中，聚合物基质的相对于固态电解质的总质量的质量百分含量记为A％；第一添加剂的相对于固态电解质的总质量的质量百分含量记为B％，二次电池满足：0.1≤B/A≤19；本申请将固态电解质和液态电解质配合使用，能够兼顾固态电解质的优点和液态电解质的优点，可以改善二次电池的动力学性能、安全性能和循环性能。

Description

二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及电池领域，具体涉及一种二次电池、电池模块、电池包和用电装置。
背景技术
二次电池具有容量高、寿命长等特性，因此广泛应用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。随着电池应用范围越来越广泛，对二次电池性能的要求也逐渐严苛。
但是在改善二次电池的性能时，难以同时兼顾二次电池的安全性能和循环性能以及动力学性能。
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、电池模块、电池包和用电装置。
本申请的第一方面提供了一种二次电池，所述二次电池包括正极极片，其包括正极膜层、负极极片、电解液和固态电解质；负极极片包括负极膜层；固态电解质设置于正极膜层和/或负极膜层的表面，固态电解质包括聚合物基质和第一添加剂，第一添加剂被配置为在正极膜层和/或负极膜层的表面形成界面膜，其中，聚合物基质的相对于固态电解质的总质量的质量百分含量记为A％；第一添加剂的相对于固态电解质的总质量的质量百分含量记为B％，二次电池满足：0.1≤B/A≤19；可选地，0.5≤B/A≤10。
由此，本申请的固态电解质中的聚合物基质具有一定的粘性，从而将固态电解质附着于活性材料的表面。固态电解质具有较好的热稳定性和化学稳定性，其在二次电池充放电过程中能够保持良好的循环稳定性，提高二次电池的循环性能。固态电解质还具有较宽的稳定电化学窗口，较宽的稳定电化学窗口能够保证在充放电过程中电解质与正负极不容易发生不良界面反应，从而降低二次电池的内阻，减少发热，提高二次电池的安全性能和使用寿命。并且第一添加剂在活性材料表面所形成的界面膜不会过厚，有利于金属离子的传输，且界面膜的阻抗较低，有利于提高二次电池的动力学性能。将固态电解质和液态电解质配合使用，能够兼顾固态电解质的优点和液态电解质的优点，可以改善二次电池的动力学性能、安全性能和循环性能。
在任意实施方式中，二次电池满足：5≤A≤99；和/或0.1≤B≤95。聚合物基质的质量百分含量在上述范围时，可以保证聚合物基质和活性材料之间的粘接力，在二次电池充放电过程中，固态电解质不易从活性材料表面脱落。第一添加剂的质量百分含量在上述范围时，可以保证第一添加剂在正极膜层和/或负极膜层形成均匀稳定的界面膜，且界面膜的阻抗相对较低，有利于提升二次电池的动力学性能。
在任意实施方式中，第一添加剂包括：含硼锂盐，其相对于固态电解质的总质量的质量百分含量记为B1％；负极成膜添加剂，其相对于固态电解质的总质量的质量百分含量记为B2％，其中，二次电池满足：0.002≤B1/B2≤10。本申请的负极成膜添加剂的质量百分含量在上述范围时，能够保证负极成膜添加剂和含硼锂盐共同形成均匀稳定的SEI膜，进一步提高对负极活性材料的防护性能。
在任意实施方式中，二次电池满足：0.1≤B1≤50；和/或0.1≤B2≤50。
在任意实施方式中，含硼锂盐的分子式为LiBF aO bC cP d，分子式中，0≤a≤4，0≤b≤8，0≤c≤4，0≤d≤4；可选地，含硼锂盐包括四氟硼酸锂LiBF 4、双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB中的一种或多种。
由此，本申请的四氟硼酸锂LiBF 4、双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB配合使用，三者形成的SEI膜的组成成分较多，SEI膜的结构更为稳定性；且在保证结构稳定的基础上，可以保证SEI膜相对较小的阻抗值，以保证二次电池的低温性能。
在任意实施方式中，负极成膜添加剂包括碳酸酯类添加剂、硫酸酯类添加剂和亚硫酸酯类添加剂中的一种或多种。本申请的负极成膜添加剂和含硼锂盐配合，共同在负极活性材料的表面形成SEI膜，且多种组分共同在SEI膜的表面成膜能够丰富SEI膜的膜层结构，并提高SEI膜的结构稳定性。
在任意实施方式中，碳酸酯类添加剂包括环状碳酸酯溶剂和/或线性碳酸酯溶剂；可选地，环状碳酸酯溶剂包括碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种；线性碳酸酯溶剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC和聚碳酸酯VA中的一种或多种；和/或硫酸酯类添加剂包括环状磺酸酯类添加剂和/或硫酸烃基酯类添加剂；可选地，环状磺酸酯类添加剂包括1,3-丙烷磺酸内酯PS、丙烯磺酸内酯PES、3-氟-1,3-丙磺酸内酯FPS中的一种或多种；和/或硫酸烃基酯类添加剂包括硫酸乙烯酯DTD、硫酸二乙酯DES和硫酸二甲酯DMS中的一种或多种；和/或亚硫酸酯类添加剂包括亚硫酸乙烯酯ES和/或乙烯基亚硫酸乙烯酯VES。
在任意实施方式中，电解液包括：环状碳酸酯溶剂，其相对于电解液的总质量的质量百分含量记为M1％；线性碳酸酯溶剂，其相对于电解液的总质量的质量百分含量记为M2％，其中，二次电池满足：10 -3≤M1/M2≤2，优选范围0.1≤M1/M2≤1；可选地，1≤M1≤20；和/或50≤M2≤85。本申请的环状碳酸酯溶剂和线性碳酸酯溶剂的质量百分含量在上述范围时，能够更进一步提升电解液的离子电导率。
在任意实施方式中，环状碳酸酯溶剂包括碳酸乙烯酯EC、碳酸丙烯酯PC、碳 酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种；和/或线性碳酸酯溶剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC、聚碳酸酯VA、碳酸二乙酯DEC、碳酸甲乙酯EMC、碳酸甲丙酯MPC、碳酸乙丙酯EPC、碳酸甲丁酯MBC、乙酸甲酯MA、乙酸乙酯EA、丙酸甲酯MP和丙酸乙酯EP中的一种或多种。
在任意实施方式中，电解液包括：电解液成膜添加剂，其基于电解液的总质量的质量百分含量记为D1％；锂盐，其基于电解液的总质量的质量百分含量记为D2％，二次电池满足：0.2≤E/(D1+D2)≤2.95，式中E表示电解液的粘度，其单位为mPa·s。
二次电池满足上述公式时，有利于提高电解液的动力学性能。例如，在添加相对较高含量的锂盐和电解液成膜添加剂的情况下，电解液的粘度得到提升，有利于电解液和固态电解质相配合，电解液成膜添加剂更易于通过固态电解质在活性材料表面成膜。在电解液在线性碳酸酯溶剂的配合下，可以进一步调控电解液的粘度在相对较低的范围内，有利于锂离子的迁移，从而保证电解液的动力学性能。
在任意实施方式中，固态电解质的溶液固体质量含量和液体质量含量的百分比记为m；正极膜层的压实密度记为P1g/cm 3正极膜层的厚度记为h1μm，二次电池满足：5≤h1*P1/m≤250。本申请的二次电池满足上述范围时，聚合物浆料可以对活性材料起到良好的包覆，起到界面保护作用，在此限定关系中，聚合物浆料的扩散路径适中，其配合聚合物浆料的粘度，有利于聚合物浆料向活性材料中扩散，并且由于配合适中的压实密度，正极膜层的孔隙率适中，有利于聚合物浆料扩散至活性材料的孔隙中，从而能够使得聚合物浆料所形成的固态电解质和活性材料的结合力度增强，并且固态电解质和活性材料界面的阻抗相对较低。
在任意实施方式中，固态电解质的溶液固体质量含量和液体质量含量的百分比记为m；负极膜层的压实密度记为P2g/cm 3负极膜层的厚度记为h2μm，二次电池满足：25≤h2*P2/m≤245。本申请的二次电池满足上述范围时，聚合物浆料可以对活性材料起到良好的包覆，聚合物浆料的扩散路径适中，其配合聚合物浆料的粘度，有利于聚合物浆料向活性材料中扩散，并且由于配合适中的压实密度，负极膜层的孔隙率适中，有利于聚合物浆料扩散至活性材料的孔隙中，从而能够使得聚合物浆料所形成的固态电解质和活性材料的结合力度增强，并且固态电解质和活性材料界面的阻抗相对较低。
本申请的第二方面还提供了一种电池模块，包括如本申请第一方面任一实施方式的二次电池。
本申请的第三方面还提供了一种电池包，包括如本申请第二方面实施方式的电池模块。
本申请第四方面还提供了一种用电装置，包括如本申请第一方面任一实施方式的二次电池、如本申请第二方面实施方式的电池模块或如本申请第三方面实施方式的电池包。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的二次电池的一实施方式的示意图。
图2是图1的二次电池的实施方式的分解示意图。
图3是本申请的电池模块的一实施方式的示意图。
图4是本申请的电池包的一实施方式的示意图。
图5是图4所示的电池包的实施方式的分解示意图。
图6是包含本申请的二次电池作为电源的用电装置的一实施方式的示意图。
附图未必按照实际的比例绘制。
附图标记说明如下：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、盖板；6、用电装置。
具体实施方式
以下，详细说明具体公开了本申请的二次电池、电池模块、电池包和用电装置的实施方式。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，方法包括步骤(a)和(b)，表示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，提到方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到方法，例如，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，“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)。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
二次电池具有容量高、寿命长等特性，因此被广泛应用；随着新能源行业的发展，对二次电池电学性能和可靠性提出了更高的要求，虽然二次电池的能量密度和电池容量等得到了提升，但是二次电池仍有可能发生安全问题，例如在高容量二次电池充放电过程中，二次电池内部积累的热量可能会导致隔离膜破坏后阴阳极接触，从而引发剧烈的氧化还原反应导致的燃烧等现象。由于液态电解质自身的安全性问题，使得二次电池的发展受到限制，因此开发具有更高安全性的二次电池具有重要意义。
在此基础上，发明人发现采用固态电解质在极片表面进行覆膜保护处理，固态电解质相较于液态电解液具有更高的热稳定性和化学稳定性，且由于固态电解质设置于极片表面，即使隔离膜破损，也可以避免阴阳极直接接触，因此具有较高的安全性。其次，固态电解质由于具有较宽的电化学窗口，能有效减少界面副反应生成，改善二次电池的循环寿命，同时具有良好的电化学稳定性，其可匹配更高充电电压的正极活性材料，故具有较高的能量密度。但是固态电解质与活性材料之间的界面为固-固界面，固态电解质和活性材料之间的有效接触较弱，金属离子在固体物质中的传输动力学较低，导致界面阻抗较大。
鉴于此，发明人对二次电池进行了深入研究，研究发现将固态电解质和电解液配合使用，在固态电解质中增加特定物质以提高对活性材料的防护性能，并降低固态电解质和活性材料之间的阻抗，提高动力学性能；且配合相对较低粘度的电解液，提高电解液的动力学性能，由此能够综合改善二次电池的动力学性能、安全性能和循环性能。接下来对本申请的技术方案进行详细说明。
二次电池
第一方面，本申请提出了一种二次电池。二次电池又称为充电电池或蓄电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。
所述二次电池包括正极极片、负极极片和电解液以及固态电解质；正极极片包括正极膜层；负极极片包括负极膜层；固态电解质设置于所述正极膜层和所述负极膜层中的至少一者的表面，所述固态电解质包括聚合物基质和第一添加剂，所述第一添 加剂被配置为在所述正极膜层和/或所述负极膜层的表面形成界面膜，其中，所述聚合物基质的相对于所述固态电解质的总质量的质量百分含量记为A％；所述第一添加剂的相对于所述固态电解质的总质量的质量百分含量记为B％，所述二次电池满足：0.5≤B/A≤19。
虽然机理并不明确，但是本申请的二次电池能够综合改善二次电池的动力学性能、安全性能和循环性能。
发明人推测本申请作用机理可能如下：
固态电解质可以设置在正极膜层上，正极膜层包括正极活性材料，即固态电解质设置于正极活性材料上，固态电解质中的第一添加剂能够和正极活性材料发生成膜反应，在正极活性材料表面形成正极固态电解质界面膜CEI膜。固态电解质也可以设置在负极膜层上，即固态电解质设置于负极活性材料上，固态电解质中的第一添加剂能够和负极活性材料发生成膜反应，在负极活性材料表面形成固体电解质界面膜(Solid Electrolyte Interphase，SEI膜)。或者固态电解质设置在正极膜层和负极膜层上，即固态电解质设置于正极活性材料上，并且固态电解质设置于负极活性材料上。在本申请中，CEI膜和SEI膜统称为界面膜。
固态电解质设置于活性材料上，固态电解质中的聚合物基质具有一定的粘性，从而将固态电解质附着于活性材料的表面。固态电解质具有较好的热稳定性和化学稳定性，其在二次电池充放电过程中能够保持良好的循环稳定性，提高二次电池的循环性能。固态电解质还具有较宽的稳定电化学窗口，较宽的稳定电化学窗口能够保证在充放电过程中电解质与正负极不容易发生不良界面反应，从而降低二次电池的内阻，减少发热，提高二次电池的安全性能和使用寿命。
聚合物基质一般为多孔状结构，其孔径较小；第一添加剂和聚合物基质形成固态电解质时，第一添加剂能够填充于聚合物基质的孔中，第一添加剂在聚合物基质中的分散较为均匀，聚合物基质中的基团能够和第一添加剂中的金属离子例如锂离子发生络合配位作用，伴随着聚合物基质的不规则布朗运动过程，金属离子在聚合物基体上反复的发生配位和解配位作用，实现锂离子的传递。由于用于成膜的第一添加剂设置于固态电解质中，第一添加剂的用量相对较少，而能够降低因引入第一添加剂而带来的水分含量，从而能够降低二次电池内部发生副反应的风险。
二次电池在注入电解液后，电解液浸润正极极片和负极极片，固态电解质在电解液的浸润下，其所包含的第一添加剂能够溶解于电解液中，溶解后的第一添加剂更容易在活性材料的表面形成界面膜，对活性材料起到良好的防护作用，且第一添加剂在活性材料表面所形成的界面膜不会过厚，有利于金属离子的传输，且界面膜的阻抗较低，有利于提高二次电池的动力学性能。此外，由于固态电解质还能够降低电解液中的溶剂和正负极极片接触发生副反应的风险，降低电解液分解的可能性。
在二次电池充电过程中，动力学过程通常包括以下步骤：以金属离子为锂离子为例进行说明，锂离子从正极活性材料脱出，向电解质相中迁移；电解液中的溶剂化锂离子向负极活性材料表面扩散传递；锂离子从负极活性材料表面得到电子，并向负 极活性材料的内部扩散。本申请在锂离子从正极活性材料脱出至电解质相中的过程中，由于正极活性材料表面的CEI膜较薄，其迁移势垒相对较低；由于电解液作为液态电解质，其粘度相对较低，离子电导率较高，故锂离子由电解液迁移至负极活性材料的过程中，其迁移势垒相对较低；由于负极活性材料表面的SEI膜较薄，锂离子由SEI膜迁移至负极活性材料内部的迁移势垒也相对较低，故，锂离子在整个动力学过程中的迁移势垒较低，所需能量较少，有利于锂离子的快速迁移，从而使得二次电池的动力学性能相对较好。
本申请将固态电解质和液态电解质配合使用，能够兼顾固态电解质的优点和液态电解质的优点，可以改善二次电池的动力学性能、安全性能和循环性能。
[固态电解质]
固态电解质包括聚合物基质和第一添加剂。在一些实施方式中，聚合物基质包括聚环氧乙烷PEO、聚氨酯PU、聚甲基丙烯酸甲酯PMMA、聚丙烯腈PAN、聚偏氟乙烯PVDF、聚(偏氟乙烯-六氟丙烯)P(VDF-HFP)、聚碳酸丙烯酯PPC和聚碳酸酯PC、聚氯乙烯PVC、聚碳酸乙烯酯PEC、聚乳酸PLA、聚四氟乙烯PTFE以及含有特征官能团的共混物和共聚物中一种或多种，特征官能团包括吸电子基团，示例性地，吸电子基团包括氟原子F、氮原子N、硫原子S、羰基-C＝O、腈基-CN以及磺酰基-S＝O等极性原子或极性基团的高分子聚合物中的一种或多种。
共混物是对材料的物理和化学性质进行调整，如PVDF-HFP/聚甲基丙烯酸乙酯PEMA、PEO/PVDF、PVDF-HFP/聚乙酸乙烯酯PVAc、PVC/PMMA、PVDF-HFP/PMMA、PVDF-HFP/PAN等各种共混体系；共聚物体系包括PEO-聚苯乙烯PSt、聚二甲基硅氧烷(PDMS)-PEO、PEGMA-MMA-IBVE、PEO-PMMA、POEM-PBMA、PPG-PEG-PPG、MMA-AN-BA等。
上述聚合物基质具有良好的机械性能，且所形成的固态电解质的柔韧性较好，能够和活性材料形成稳定良好的电极电解质界面；此外上述聚合物基质聚合物的分子链段具有热运动的能力，且随着温度的升高分子链段热运动加剧，聚合物基体具备传导锂离子的能力，有利于金属离子例如锂离子不断发生与特征原子和基团间发生配位-解离-配位的过程，从而实现锂离子在聚合物基质分子链内部或分子链之间的传输，使得所形成的固态电解质具有高的离子电导率。
在一些实施方式中，基于固态电解质的总质量计，聚合物基质的质量百分含量A％为：5≤A≤99。聚合物基质的质量百分含量在上述范围时，可以保证聚合物基质和活性材料之间的粘接力，在二次电池充放电过程中，固态电解质不易从活性材料表面脱落。可选地，5≤A≤70；示例性地，聚合物基质的质量百分含量A％可以为5％、10％、15％、25％、35％、45％、55％、65％、70％、90％、95％或99％；或者是上述任意两个数值组成的范围。
在一些实施方式中，第一添加剂可以用于在正极膜层和/或负极膜层的表面形成界面膜。基于固态电解质的总质量计，第一添加剂的质量百分含量B％为：0.1≤B≤95。
第一添加剂的质量百分含量在上述范围时，可以保证第一添加剂在正极膜层和 /或负极膜层形成均匀稳定的界面膜，且界面膜的阻抗相对较低，有利于提升二次电池的动力学性能。可选地，10≤B≤95；示例性地，第一添加剂的质量百分含量B％可以为0.1％、1％、5％、10％、20％、30％、40％、50％、60％、70％、80％或95％；或者是上述任意两个数值组成的范围。
在一些实施方式中，第一添加剂可以包括导电锂盐，以保证锂离子的顺利迁移。导电锂盐可以选用含硼锂盐。含硼锂盐与聚合物基质的相容性较好，且含硼锂盐的加入能够在一定程度上降低聚合物基质的玻璃转化温度，提高聚合物基质的机械强度和无定型相的稳定温度。含硼锂盐的阴离子基团较大，容易解离出锂离子，从而保证锂离子的溶解度，提升聚合物电解质离子电导率。
在一些实施方式中，含硼锂盐的分子式为LiBF aO bC cP d，分子式中，0≤a≤4，0≤b≤8，0≤c≤4，0≤d≤4。
B原子可以与含氧的草酸类配体相结合，结合后的产物具有优异的热稳定性，易于在负极活性材料的表面形成性能优良的SEI膜，从而能够保证负极活性材料的结构稳定性，进而改善二次电池的循环性能。当然B原子也可以和卤素原子尤其是氟原子相结合，氟原子的吸电子诱导效应较强，其热稳定性和化学稳定性较高，且锂离子在电解液中的溶解度较高，能够保证锂离子的溶解度，从而保证电解液的电导率。
作为示例，含硼锂盐包括四氟硼酸锂(LiBF 4)、双草酸硼酸锂(LiB(C 2O 4) 2，简称LiBOB)和双氟草酸硼酸锂(LiBC 2O 4F 2，简称LiDFOB)中的一种或多种。进一步地，含硼锂盐包括四氟硼酸锂LiBF 4、双草酸硼酸锂(LiB(C 2O 4) 2，简称LiBOB)和双氟草酸硼酸锂(LiBC 2O 4F 2，简称LiDFOB)的组合物。
四氟硼酸锂(LiBF 4)在和电解液中的有机溶剂例如碳酸酯类溶剂或添加剂配合使用时，四氟硼酸锂所构成的体系的粘度相对较低，有利于锂离子的释放，从而使得电解液中的电导率得到提升。四氟硼酸锂所形成的SEI膜的厚度较均匀，动力学活性较好，二次电池中的电荷转移阻抗较小，由此可以显著改善二次电池的低温性能；SEI膜不易发生热分解，其在高温下的性能较为稳定，故其可以显著改善二次电池的高温性能。
双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB中的任意一者具有对正极极片中的正极集流体的钝化作用，能够降低和正极集流体发生副反应腐蚀正极集流体的风险，提高正极极片的结构稳定性。并且包含双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB中的任意一者的电解液不易产生酸性物质，也可以进一步起到降低正极集流体被腐蚀的风险。双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB和正极活性材料的相容性较好，有利于锂离子的迁移；其能够在负极活性材料的表面形成有效的SEI膜，提高对负极活性材料的防护性能。
四氟硼酸锂LiBF 4、双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB配合使用，三者形成的SEI膜的组成成分较多，SEI膜的结构更为稳定性；且在保证结构稳定的基础上，可以保证SEI膜相对较小的阻抗值，以保证二次电池的低温性能。
在一些实施方式中，基于固态电解质的总质量计，含硼锂盐的质量百分含量记 为B1％，0.1≤B1≤50。
含硼锂盐的质量百分含量在上述范围时，能够保证固态电解质的导离子能力；以及可以起到对正极集流体的良好的防护作用，并可以对负极活性材料起到良好的防护作用。示例性地，含硼锂盐的质量百分含量B1％可以为0.1％、0.5％、1％、2％、10％、20％、25％或50％等。
在一些实施方式中，导电锂盐还可以包括导离子锂盐，导离子锂盐包括六氟磷酸锂LiPF 6、二氟磷酸锂LiPO 2F 2、二氟双草酸磷酸锂LiDODFP、四氟草酸磷酸锂LiDFBP、双氟磺酰亚胺锂盐LiFSI、双三氟甲基磺酰亚胺锂LiTFSI、氟磺酸锂LiSO 3F、硝酸锂LiNO 3、高氯酸锂LiClO 4、六氟锑酸锂LiSbF 6、六氟砷酸锂LiAsF 6中的一种或多种。上述导离子锂盐的解离度相对较高，其电导率高，有利于锂离子的迁移。
在一些实施方式中，第一添加剂可以包括负极成膜添加剂，负极成膜添加剂包括碳酸酯类添加剂、硫酸酯类添加剂和亚硫酸酯类添加剂中的一种或多种。
负极成膜添加剂和含硼锂盐配合，共同在负极活性材料的表面形成SEI膜，且多种组分共同在SEI膜的表面成膜能够丰富SEI膜的膜层结构，并提高SEI膜的结构稳定性。进一步地，负极成膜添加剂包括碳酸酯类添加剂、硫酸酯类添加剂、亚硫酸酯类添加剂和氟代草酸磷酸锂盐中的至少两种；其所形成的SEI膜的组成较为丰富，其结构稳定性更高。
基于固态电解质的总质量计，负极成膜添加剂的质量百分含量记为B2％，0.1≤B2≤50。
负极成膜添加剂的质量百分含量在上述范围时，能够保证负极成膜添加剂形成均匀稳定的SEI膜，进一步提高对负极活性材料的防护性能。示例性地，负极成膜添加剂的质量百分含量B2％可以为0.1％、0.5％、1％、2％、10％、20％、25％或50％等。
在一些实施方式中，0.002≤B1/B2≤9。
负极成膜添加剂的质量百分含量在上述范围时，能够保证负极成膜添加剂和含硼锂盐共同形成均匀稳定的SEI膜，进一步提高对负极活性材料的防护性能。示例性地，B1/B2可以为0.002、0.2、0.5、1、2、5或9等。
作为示例，碳酸酯类添加剂包括环状碳酸酯类添加剂和/或线性碳酸酯类添加剂。进一步地，所述环状碳酸酯类添加剂包括碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种。所述线性碳酸酯类添加剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC和聚碳酸酯VA中的一种或多种。
作为示例，硫酸酯类添加剂包括环状磺酸酯类添加剂和/或硫酸烃基酯类添加剂。进一步地，所述环状磺酸酯类添加剂包括1,3-丙烷磺酸内酯PS、丙烯磺酸内酯PES、3-氟-1,3-丙磺酸内酯FPS中的一种或多种。所述硫酸烃基酯类添加剂包括硫酸乙烯酯DTD、硫酸二乙酯DES和硫酸二甲酯DMS中的一种或多种。
作为示例，所述亚硫酸酯类添加剂包括亚硫酸乙烯酯ES和/或乙烯基亚硫酸乙烯酯VES。
在一些实施方式中，固态电解质中还可以包括溶剂，例如乙腈、四氢呋喃、丙酮、N-甲基吡咯烷酮、N,N-二甲基甲酰胺，乙腈、四氢呋喃、丙酮、N-甲基吡咯烷酮、N,N-二甲基甲酰胺中的至少一种，以增加聚合物基质和第一添加剂等之间的相容性。
在一些实施方式中，固态电解质中还可以包括助剂，例如增塑剂、离子液体等，以提升固态电解质的离子电导率和锂离子迁移数，并且可以改善电极电解质界面的界面相容性。示例性地，增塑剂可以为碳酸乙烯酯EC、碳酸亚丙酯PC等。
可以采用以下方法制备固态电解质：将聚合物基质、第一添加剂等混合均匀后形成聚合物浆料，采用溶液浇筑法涂布转移至极片表面，并固化成膜。
[电解液]
电解液在正极极片和负极极片之间起到传导金属离子的作用，本申请的电解液可采用本领域公知的用于二次电池的电解液。电解液包括锂盐和有机溶剂。
在一些实施方式中，锂盐可选自六氟磷酸锂LiPF 6、二氟磷酸锂LiPO 2F 2、二氟双草酸磷酸锂LiDODFP、四氟草酸磷酸锂LiDFBP、双氟磺酰亚胺锂盐LiFSI、双三氟甲基磺酰亚胺锂LiTFSI、氟磺酸锂LiSO 3F、硝酸锂LiNO 3、高氯酸锂LiClO 4、六氟锑酸锂LiSbF 6、六氟砷酸锂LiAsF 6中的一种或多种的至少一种。基于电解液的总质量计，锂盐的质量百分含量记为D2％。
进一步的，1≤D2≤25，锂盐在上述范围内可以保证电解液提供充足的锂源形成离子通路，同时使得电解液具有高的离子电导。
示例性地，D2可以为1、2、3、4、5、6、7、8、9、10、12、15、17、19、20、21、22、23或25；或者是上述任意两个数值组成的范围。
在一些实施方式中，有机溶剂可以包括碳酸酯溶剂；碳酸酯溶剂包括环状碳酸酯溶剂和线性碳酸酯溶剂。环状碳酸酯溶剂和线性碳酸酯溶剂配合使用，使得电解液具有高介电常数和低粘度，其可以提高电解液的离子电导率；且电解液的电化学稳定性较高，电化学窗口得到显著提升。
在一些实施方式中，环状碳酸酯溶剂相对于所述电解液的总质量的质量百分含量记为M1％，线性碳酸酯溶剂相对于所述电解液的总质量的质量百分含量记为M2％，10 -3≤M1/M2≤2。
环状碳酸酯溶剂和线性碳酸酯溶剂的质量百分含量在上述范围时，能够更进一步提升电解液的离子电导率。可选地，0.1≤M1/M2≤1；示例性地，M1/M2可以为0.001、0.01、0.1、0.2、0.5、0.7、0.9或1；或者是上述任意两个数值组成的范围。
作为示例，所述环状碳酸酯溶剂包括碳酸乙烯酯EC、碳酸丙烯酯PC、碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种。
进一步地，1≤M1≤20；环状碳酸酯溶剂的质量百分含量在上述范围时，其促进锂离子的解离，锂离子的溶解度较高，从而能够进一步提高电解液的离子电导率。示例性地，M1可以为1、5、7、8、9、10、11、12、13、14、15、16、17、18、19或20；或者是上述任意两个数值组成的范围。
作为示例，所述线性碳酸酯溶剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC、聚碳酸酯VA、碳酸二乙酯DEC、碳酸甲乙酯EMC、碳酸甲丙酯MPC、碳酸乙丙酯EPC、碳酸甲丁酯MBC、乙酸甲酯MA、乙酸乙酯EA、丙酸甲酯MP和丙酸乙酯EP中的一种或多种。
进一步地，50≤M2≤85；线性碳酸酯溶剂的质量百分含量在上述范围时，其可以为电解液提供较低的粘度，有利于锂离子的顺利迁移，提升电解液的动力学性能。示例性地，M2可以为50、52、55、56、58、60、62、65、66、68或85。
在一些实施方式中，有机溶剂还可以包括醚类溶剂，醚类溶剂由于具有较低的粘度因而能够使得电解液的离子电导率较高，使得电解液中的锂离子在循环过程中保持良好的形态结构。示例性地，醚类溶剂包括***、聚甲氧基醚等。
在一些实施方式中，有机溶剂还可以包括腈类溶剂，腈类溶剂具有较高的稳定性，从而能够提升电解液整体的稳定性。示例性地，腈类溶剂可以包括己二腈、戊二腈等。
当然，有机溶剂还可以包括其他类型的溶剂，如砜类溶剂等。
示例性地，有机溶剂选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、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电解液添加剂。例如电解液添加剂可以包括负极成膜添加剂、正极成膜添加剂等电解液成膜添加剂，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。例如负极成膜添加剂包括碳酸酯类添加剂、硫酸酯类添加剂和亚硫酸酯类添加剂中的一种或多种。电解液成膜添加剂的具体种类如固态电解质中所阐述，在此不再赘述。基于电解液的总质量计，电解液成膜添加剂的质量百分含量记为D1％。
可选地，10 -3≤D1≤10，D1在上述范围时，可以保证在活性材料的表面充分形成界面膜，以提高对活性材料的防护作用。可选地，0.1≤D1≤10；示例性地，D1可以为10 -3、10 -2、0.1、0.5、1、2、3、4、5、6、7、8、9或10；或者是上述任意两个数值组成的范围。
在一些实施方式中，二次电池还满足：0.2≤E/(D2+D1)≤2.95；式中，E表示电解液的粘度，其单位为mPa·s。
二次电池满足上述公式时，有利于提高电解液的动力学性能。例如，在添加相对较高含量的锂盐和电解液成膜添加剂的情况下，电解液的粘度得到提升，有利于电解液和固态电解质相配合，电解液成膜添加剂更易于通过固态电解质在活性材料表面成膜。在电解液在线性碳酸酯溶剂的配合下，可以进一步调控电解液的粘度在相对较低的范围内，有利于锂离子的迁移，从而保证电解液的动力学性能。示例性地，E/(D2+D1)可以为0.2、0.25、0.28，1、1.2、1.5、1.8、2、2.5或2.95；或者是上述任意两个数值组成的范围。
进一步地，0.1≤E≤8；示例性地，E可以为0.1、0.5、1、1.5、2、2.5、3、3.5、4、5、6、7或8；或者是上述任意两个数值组成的范围。E在上述范围时，可以调控电解液的粘度在合适的范围内，从而有利于锂离子的迁移。
[正极极片]
在一些实施方式中，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上的正极膜层。例如，正极集流体具有在自身厚度方向相对的两个表面，正极膜层设置于正极集流体的两个相对表面中的任意一者或两者上。
在一些实施方式中，将固态电解质设置于正极膜层的表面上，即设置于正极膜层的背离正极集流体的表面上，可以对正极极片起到良好的防护作用，从而保证正极极片的结构稳定性，提高二次电池的循环性能。
在一些实施方式中，固态电解质的溶液固体质量和液体质量百分比记为m；所述正极膜层的压实密度记为P1g/cm 3；所述正极膜层的厚度记为h1μm；二次电池满足：5≤h1*P1/m≤250。
固态电解质中的固态物质包括聚合物基质、含硼锂盐等，其相对于固态电解质的质量百分含量为固态电解质的溶液固体质量含量。固态电解液中的液态物质如溶剂等，其相对于固态电解质的质量百分含量为固态电解质的液体质量含量。溶液固体质量含量和液体质量含量的百分比为m。
本申请中，材料的压实密度为本领域公知的含义，可以用本领域已知的仪器及方法进行测试。例如可以参照标准GB/T24533-2009，通过电子压力试验机(例如UTM7305型)测试。示例性测试方法如下：称取1g材料，加入底面积为1.327cm 2的模具中，加压至2000kg(相当于20000N)，保压30s，然后卸压，保持10s，然后记录并计算得到材料在20000N作用力下的压实密度。
二次电池满足上述范围时，聚合物浆料可以对活性材料起到良好的包覆，起到界面保护作用，在此限定关系中，聚合物浆料的扩散路径适中，其配合聚合物浆料的粘度，有利于聚合物浆料向活性材料中扩散，并且由于配合适中的压实密度，正极膜层的孔隙率适中，有利于聚合物浆料扩散至活性材料的孔隙中，从而能够使得聚合物浆料所形成的固态电解质和活性材料的结合力度增强，并且固态电解质和活性材料界面的阻抗相对较低。可选地，100≤h1×P1/m≤250；示例性地，h1*P1/m可以为0.4、0.8、1、2、3、5、8、10、15、20、25、30、35、40、45、50、55、60、65、70、75、80、85、90、100、110、120、150、160、170、180、190、200、220、250、260、280或300；或者是上述任意两个数值组成的范围。
进一步地，1≤m≤50。m可以为1、2、5、10、15、20、25、30、35、40、45或50；或者是上述任意两个数值组成的范围。
进一步地，10≤h1≤300。h1可以为10、20、50、60、80、100、120、150、180、200、220、250、280、300；或者是上述任意两个数值组成的范围。
进一步地，0.1≤P1≤5。P1可以为0.1、0.5、1、1.5、2.0、2.5、3.0、3.5、4.0、4.5或5；或者是上述任意两个数值组成的范围。
所述正极膜层包括正极活性材料，所述正极活性材料可采用本领域公知的用于二次电池的正极活性材料。例如，所述正极活性材料可包括锂过渡金属氧化物、橄榄石结构的含锂磷酸盐及其各自的改性化合物中的至少一种。锂过渡金属氧化物的示例可包括锂钴氧化物、锂镍氧化物、锂锰氧化物、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、锂镍钴铝氧化物及其各自的改性化合物中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、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及其各自的改性化合物中的至少一种。本申请并不限定于这些材料，还可以使用其他可被用作二次电池正极活性材料的传统公知的材料。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。
在一些实施例中，正极活性材料包括LiNi xCo yMn zM 1-x-y-zO 2或LiNi aCo bAl cN 1-a-b- cO 2，其中，M和N各自独立的选自Co、Ni、Mn、Mg、Cu、Zn、Al、Sn、B、Ga、Cr、Sr、V和Ti中的任意一种，且0≤y≤1，0≤x＜1，0≤z≤1，x+y+z≤1，0≤a≤1，0≤b≤1，0≤c≤1，a+b+c≤1。正极活性材料与含硼锂盐配合使用，含硼锂盐中的B原子容易与正极活性材料中的O原子结合，从而降低正极活性材料的电荷转移电阻、降低锂离子在正极活性材料体相内的扩散阻力。因此，当非水电解液中含有合适含量的四氟硼酸锂和双氟草酸硼酸锂时，低钴或无钴正极活性材料能具有显著改善的锂离子扩散速率，低钴或无钴正极活性材料体相内的锂离子能及时地补充到表面，避免低钴或无钴正极活性材料表面过脱锂，从而稳定低钴或无钴正极活性材料的晶体结构。由于低钴或无钴正极活性材料的晶体结构更稳定，因此能够极大地降低由于低钴或无钴正极活性材料表面出现过脱锂而导致正极活性材料结构性质、化学性质或电化学性质变得不稳定等问题出现的概率，例如，正极活性材料不可逆畸变和晶格缺陷增加的问题。
LiNi xCo yMn zM 1-x-y-zO 2或LiNi aCo bAl cN 1-a-b-cO 2可以按照本领域常规方法制备。示例性制备方法如下：将锂源、镍源、钴源、锰源、铝源、M元素前驱体、N元素前驱体混合后烧结得到。烧结气氛可为含氧气氛，例如，空气气氛或氧气气氛。烧结气氛的O 2浓度例如为70％至100％。烧结温度和烧结时间可根据实际情况进行调节。
作为示例，锂源包括但不限于氧化锂(Li 2O)、磷酸锂(Li 3PO 4)、磷酸二氢锂(LiH 2PO 4)、醋酸锂(CH 3COOLi)、氢氧化锂(LiOH)、碳酸锂(Li 2CO 3)及硝酸锂(LiNO 3)中的至少一种。作为示例，镍源包括但不限于硫酸镍、硝酸镍、氯化镍、草酸镍及醋酸镍中的至少一种。作为示例，钴源包括但不限于硫酸钴、硝酸钴、氯化钴、草酸钴及醋酸钴中的至少一种。作为示例，锰源包括但不限于硫酸锰、硝酸锰、氯化锰、草酸锰及醋酸锰中的至少一种。作为示例，铝源包括但不限于硫酸铝、硝酸铝、氯化铝、草酸铝及醋酸铝中的至少一种。作为示例，M元素前驱体包括但不限于M元素的氧化物、硝酸化合物、碳酸化合物、氢氧化合物及醋酸化合物中的至少一种。作为示例，N元素的前驱体包括但不限于氟化铵、氟化锂、氟化氢、氯化铵、氯化锂、氯化氢、硝酸铵、亚硝酸铵、碳酸铵、碳酸氢铵、磷酸铵、磷酸、硫酸铵、硫酸氢铵、亚硫酸氢铵、亚硫酸铵、硫化氢铵、硫化氢、硫化锂、硫化铵及单质硫中的至少一种。
在一些实施例中，基于正极膜层的总质量计，分子式为LiNi xCo yMn zM 1-x-y-zO 2或LiNi aCo bAl cN 1-a-b-cO 2的层状材料的质量百分含量为80％至99％。例如，分子式为LiNi xCo yMn zM 1-x-y-zO 2或LiNi aCo bAl cN 1-a-b-cO 2的层状材料的质量百分含量可以为80％，81％，82％，83％，84％，85％，86％，87％，88％，89％，90％，91％，92％，93％，94％，95％，96％，97％，98％，99％或以上任何数值所组成的范围。可选地，分子式为LiNi xCo yMn zM 1-x-y-zO 2或LiNi aCo bAl cN 1-a-b-cO 2的层状材料的质量百分含量为85％至99％，90％至99％，95％至99％，80％至98％，85％至98％，90％至98％，95％至98％，80％至97％，85％至97％，90％至97％或95％至97％。
在一些实施例中，正极膜层还可选地包括正极导电剂。本申请对正极导电剂的种类没有特别的限制，作为示例，正极导电剂包括选自超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或多种的组合。在一些实施例中，基于正极膜层的总质量，正极导电剂的质量百分含量在5％以下。
在一些实施例中，正极膜层还可选地包括正极粘结剂。本申请对正极粘结剂的种类没有特别的限制，作为示例，正极粘结剂可包括选自聚偏氟乙烯(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-六氟丙烯共聚物和含氟丙烯酸酯类树脂中的一种或多种的组合。在一些实施例中，基于正极膜层的总质量，正极粘结剂的质量百分含量在5％以下。
在一些实施例中，正极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铝箔或铝合金箔。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层，作为示例，金属材料可包括选自铝、铝合金、镍、镍合金、钛、钛合金、银和银合金中的一种或多种的组合，高分子材料基层可包括选自聚丙烯(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)和聚乙烯(PE)中的一种或多种的组合。
正极膜层通常是将正极浆料涂布在正极集流体上，经干燥、冷压而成的。正极浆料通常是将正极活性材料、可选的导电剂、可选的粘结剂以及任意的其他组分分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)，但不限于此。
本申请的电解液可以按照本领域常规的方法制备。例如，可以将添加剂、溶剂、电解质盐等混合均匀，得到电解液。各物料的添加顺序并没有特别的限制，例如，可以将添加剂、电解质盐等加入到非水溶剂中混合均匀，得到非水电解液。
在本申请中，电解液中各组分及其含量可以按照本领域已知的方法测定。例如，可以通过气相色谱-质谱联用法(GC-MS)、离子色谱法(IC)、液相色谱法(LC)、核磁共振波谱法(NMR)等进行测定。
需要说明的是，本申请的电解液测试时，可直接取新鲜制备的电解液，也可以从二次电池中获取电解液。从二次电池中获取电解液的一个示例性方法包括如下步骤：将二次电池放电至放电截止电压(为了安全起见，一般使电池处于满放状态)后进行离心处理，之后取适量离心处理得到的液体即为非水电解液。也可以从二次电池的注液口直接获取非水电解液。
[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，将固态电解质设置于负极膜层的表面上，即设置于负极膜层的背离负极集流体的表面上，可以对负极极片起到良好的防护作用，从而保证负极极片的结构稳定性，提高二次电池的循环性能。
在一些实施方式中，固态电解质的溶液固体质量含量和液体质量含量的百分比记为m；所述负极膜层在20000N作用力下的压实密度记为P2g/cm 3；所述负极膜层的厚度记为h2μm；二次电池满足：25≤h2×P2/m≤245。
二次电池满足上述范围时，聚合物浆料可以对活性材料起到良好的包覆，聚合物浆料的扩散路径适中，其配合聚合物浆料的粘度，有利于聚合物浆料向活性材料中扩散，并且由于配合适中的压实密度，负极膜层的孔隙率适中，有利于聚合物浆料扩散至活性材料的孔隙中，从而能够使得聚合物浆料所形成的固态电解质和活性材料的结合力度增强，并且固态电解质和活性材料界面的阻抗相对较低。可选地，50≤h2*P2/m≤200；示例性地，h2*P2/m可以为0.04、0.08、0.1、0.2、0.3、0.4、0.8、1、2、3、5、8、10、15、20、25、30、35、40、45、50、55、60、65、70、75、80、85、90、100、110、120、150、160、170、180、190或200；或者是上述任意两个数值组成的范围。
进一步地，1≤m≤50。m可以为1、2、5、10、15、20、25、30、35、40、45或50或者是上述任意两个数值组成的范围。
进一步地，10≤h2≤300。h2可以为10、20、50、60、80、100、120、150、180、200、220、250、280、300；或者是上述任意两个数值组成的范围。
进一步地，1≤P2≤5。P2可以为1、1.5、2.0、2.5、3.0、3.5、4.0、4.5或5；或者是上述任意两个数值组成的范围。
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、钛酸锂和锂铝合金等。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。
在一些实施例中，负极膜层还可选地包括负极粘结剂。本申请对负极粘结剂的种类没有特别的限制，作为示例，负极粘结剂可包括选自丁苯橡胶(SBR)、水溶性不饱和树脂SR-1B、水性丙烯酸类树脂(例如，聚丙烯酸PAA、聚甲基丙烯酸PMAA、聚丙烯酸钠PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)和 羧甲基壳聚糖(CMCS)中的一种或多种的组合。在一些实施例中，基于负极膜层的总质量，负极粘结剂的质量百分含量在5％以下。
在一些实施例中，负极膜层还可选地包括负极导电剂。本申请对负极导电剂的种类没有特别的限制，作为示例，负极导电剂可包括选自超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或多种的组合。在一些实施例中，基于负极膜层的总质量，负极导电剂的质量百分含量在5％以下。
在一些实施例中，负极膜层还可选地包括其他助剂。作为示例，其他助剂可包括增稠剂，例如，羧甲基纤维素钠(CMC-Na)、PTC热敏电阻材料等。在一些实施例中，基于负极膜层的总质量，其他助剂的质量百分含量在2％以下。
在一些实施例中，负极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铜箔或铜合金箔。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层，作为示例，金属材料可包括选自铜、铜合金、镍、镍合金、钛、钛合金、银和银合金中的一种或多种的组合，高分子材料基层可包括选自聚丙烯(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)和聚乙烯(PE)中的一种或多种的组合。
负极膜层通常是将负极浆料涂布在负极集流体上，经干燥、冷压而成的。负极浆料通常是将负极活性材料、可选的导电剂、可选地粘结剂、其他可选的助剂分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，但不限于此。
负极极片并不排除除了负极膜层之外的其他附加功能层。例如在某些实施例中，负极极片还包括覆盖在负极膜层表面的保护层。
在本申请中物质的质量百分含量的测定方法，可以按照本领域已知的方法测定。例如，可以通过气相色谱-质谱联用法(GC-MS)、离子色谱法(IC)、液相色谱法(LC)、核磁共振波谱法(NMR)等进行测定。
[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。如图1是作为一个示例的方形结构的二次电池5。
在一些实施例中，如图1和图2所示，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用于盖设开口，以封闭容纳腔。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封装于容纳腔。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，可根据需求来调节。
本申请的二次电池的制备方法是公知的。在一些实施例中，可将正极极片、隔离膜、负极极片和电解液组装形成二次电池。作为示例，可将正极极片、隔离膜、负极极片经卷绕工艺或叠片工艺形成电极组件，将电极组件置于外包装中，烘干后注入电解液，经过真空封装、静置、化成、整形等工序，得到二次电池。
在本申请的一些实施例中，根据本申请的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多个，具体数量可根据电池模块的应用和容量来调节。
图3是作为一个示例的电池模块4的示意图。如图3所示，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。
在一些实施例中，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根据电池包的应用和容量进行调节。
图4和图5是作为一个示例的电池包1的示意图。如图4和图5所示，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用于盖设下箱体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。
用电装置
第二方面，本申请提供一种用电装置，用电装置包括本申请的二次电池、电池模块和电池包中的至少一种。二次电池、电池模块和电池包可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以但不限于是移动设备(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。
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的示意图。该用电装置6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高功率和高能量密度的 需求，可以采用电池包1或电池模块。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于质量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例1
1、正极极片的制备
采用厚度为12μm的铝箔作为正极集流体。
将正极活性材料LiNi 0.6Co 0.2Mn 0.2O 2、导电剂炭黑、粘结剂聚偏氟乙烯(PVDF)按重量比97.5:1.4:1.1在适量的溶剂NMP中充分搅拌混合，形成均匀的正极浆料；将正极浆料均匀涂覆于正极集流体铝箔的表面上，经干燥、冷压后，得到正极膜层。
将聚合物基质P(VDF-HFP)、含硼锂盐(LiBOB)和锂盐LiTFSI搅拌均匀形成聚合物浆料，真空除泡后溶液浇筑涂布于正极膜层上，于5℃～35℃下，在0.1％～30％的湿度环境下放置12h，相转移固化形成固态电解质。
2、负极极片的制备
采用厚度为8μm的铜箔作为负极集流体。
将负极活性材料石墨、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC-Na)、导电剂炭黑(Super P)按重量比96.2:1.8:1.2:0.8在适量的溶剂去离子水中充分搅拌混合，形成均匀的负极浆料；将负极浆料均匀涂覆于负极集流体铜箔的表面上，经干燥、冷压后，得到负极膜层。
将聚合物基质P(VDF-HFP)、含硼锂盐(LiBF 4)和锂盐LiTFSI，真空除泡后涂布于负极膜层上，于5℃～35℃下，在0.1％～30％的湿度环境下放置12h，固化形成固态电解质。
3、隔离膜
采用多孔聚乙烯(PE)膜作为隔离膜。
4、电解液的制备
在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯、碳酸甲乙酯、碳酸二乙酯按照体积比1:1:1进行混合得到电解液溶剂，随后将锂盐溶解于混合后的溶剂中，配置成锂盐浓度为1mol/L的电解液。
5、二次电池的制备
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离作用，然后卷绕得到电极组件；将电极组件置于外包装壳中，干 燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到锂离子电池。
实施例2
实施例2-1至实施例2-12的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，实施例2-1至实施例2-12调整了第一添加剂和聚合物基质的质量百分含量。
对比例1和对比例2
对比例1和对比例2的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，对比例1和对比例2调整了第一添加剂和聚合物基质的质量百分含量。实施例1、实施例2和对比例的数据如表1所示。
表1
Figure PCTCN2022105827-appb-000001
实施例3
实施例3-1至实施例3-5的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，实施例3-1至实施例3-5调整了含硼锂盐的质量百分含量B1％。实施例1和实施例3的数据如表2所示。
表2
Figure PCTCN2022105827-appb-000002
实施例4
实施例4-1至实施例4-7的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，实施例4-1至实施例4-7调整了电解液成膜添加剂的质量百分含量D1％。实施例1和实施例4的数据如表3所示。
表3
Figure PCTCN2022105827-appb-000003
实施例5
实施例5-1至实施例5-8的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，实施例5-1至实施例5-8调整了正极膜层的压实密度P1等参数。实施例1和实施例5的数据如表4所示。
表4
Figure PCTCN2022105827-appb-000004
Figure PCTCN2022105827-appb-000005
实施例6
实施例6-1至实施例6-6的二次电池按照与实施例1类似的方法制备，与实施例1不同的是，实施例6-1至实施例6-6调整了负极膜层的压实密度P2等参数。实施例6-1至实施例6-6的数据如表5所示。
表5
Figure PCTCN2022105827-appb-000006
测试部分
1、正极极片/负极极片的参数测试
1.1正极膜层/负极膜层的厚度测试
采用万分尺沿正极极片的厚度方向测量至少12个不同位置的正极极片的厚度，然后取平均值作为负极极片的厚度h1；然后减去负极集流体的厚度即为正极膜层的厚度。
采用万分尺沿负极极片的厚度方向测量至少12个不同位置的负极极片的厚度，然后取平均值作为负极极片的厚度h2；然后减去正极集流体的厚度即为负极膜层的厚度。
1.2正极膜层/负极膜层的压实密度P的测试
取一定量上述制备的负极活性材料样品样品，加入UTM7305型电子压力试验机的底面积为1.327cm2的模具中，加压至2000kg(相当于20000N)，保压30s，然后卸压，保持10s，然后记录并计算得到负极活性材料在20000N作用力下的粉体压实密度。测试标准依据GB/T24533-2009。
取一定量上述制备的正极活性材料样品，加入UTM7305型电子压力试验机的 底面积为1.327cm2的模具中，加压至2000kg(相当于20000N)，保压30s，然后卸压，保持10s，然后记录并计算得到正极活性材料在20000N作用力下的粉体压实密度。测试标准依据GB/T24533-2009。
2、电解液的粘度测试
取适量电解液样品先润洗样品杯及转子，后倒取适量电解液与样品杯，恒温至待测25℃温度，用DV-2TLV粘度计(计算公式为FSR＝TK*SMC*10000/RPM)，电解液及有机溶剂固定选取18#转子，70r/min转速，选择Multi Point Average(多点平均值)数据采集模式，开始自动检测记录。测试标准依据GB/T 10247-2008
3、二次电池的性能测试
3.1二次电池的循环性能测试
(1)二次电池常温循环性能测试
在25℃下，将二次电池以1C恒流充电至4.4V，继续恒压充电至电流为0.05C，此时二次电池为满充状态，记录此时的充电容量，即为第1圈充电容量；将二次电池静置5min后，以1C恒流放电至2.8V，此为一个循环充放电过程，记录此时的放电容量，即为第1圈放电容量。将二次电池按照上述方法进行循环充放电测试，记录每圈循环后的放电容量。二次电池25℃循环600圈容量保持率(％)＝600圈循环后的放电容量/第1圈放电容量×100％。
3.2二次电池的安全性能测试
在25℃下，将二次电池以1C恒流充电到4.3V，继续恒压充电至电流为0.05C，此时二次电池为满充状态；将满充状态的二次电池置于密封良好的高温箱中，以5℃/min升温至100℃，保持1小时后以5℃/min升温至105℃，保持30分钟；之后以5℃/min升温速率每升高5℃后保持30min，直至二次电池失效，记录二次电池失效前的最高温度T max。T max越高，二次电池的热箱安全性能越好。
为保证测试结果可靠性，上述各测试可采用至少3个平行样本进行测试并取平均值作为测试结果。
3.3二次电池电芯直流阻抗DCR测试
25℃DCR测试：先进行容量测试，具体操作流程为将二次电池用恒流充放电测试仪在25℃温度下静置2h，用以0.33C倍率充电至4.4V，后恒压充电至电流小于0.05C；静置5min，然后放电至2.8V记录此时的放电容量为二次电池初始容量。然后调节电池剩余电量(以SOC表示，公式为剩余电量/初始电量×100％)，进行测试DCR，先将0.33C电池满充至4.4V，恒压充电至4.4V至电流小于0.05C，然后以0.05C满放1h，恒流放电并调整二次电池至50％SOC，此时二次电池的电压记为U 1；将二次电池以4C的电流I 1恒流放电30秒，采用0.1秒采点，放电末期电压记为U 2。用二次电池50％SOC时的放电直流内阻表示二次电池的初始直流内阻，二次电池的初始直流内阻(mΩ)＝(U 1-U 2)/I 1。
测试结果
本申请在改善二次电池的循环性能、安全性能和动力学性能方面的作用如表6 至表10所示。
表6
项目 25℃循环600圈容量保持率(％) Tmax(℃) 25℃DCR(mΩ)
实施例1 88.51％ 134 22
实施例2-1 89.44％ 138 24
实施例2-2 88.82％ 142 25
实施例2-3 85.63％ 144 27
实施例2-4 81.23％ 147 32
实施例2-5 80.24％ 151 35
实施例2-6 78.30％ 153 37
实施例2-7 77.52％ 155 38
实施例2-8 79.56％ 152 36
实施例2-9 85.50％ 145 25
实施例2-10 76.43％ 158 42
实施例2-11 79.32％ 152 39
实施例2-12 80.25％ 145 31
对比例1 72.47％ 165 48
对比例2 71.45％ 168 51
由表6可知，采用固态电解质附着于极片上可以改善二次电池的安全性能，但是由对比例1和对比例2可知，锂离子的界面传输动力学较差，界面阻抗较大。而实施例1至实施例2-12通过调控固态电解质中的聚合物基质和第一添加剂的质量百分含量在合适范围内例如0.1≤B/A≤19；可选地，0.5≤B/A≤10；可以显著改善二次电池的阻抗，以提升其动力学性能；且二次电池的循环性能和安全性能也能够得到改善。
表7
项目 25℃循环600圈容量保持率(％) Tmax(℃) 25℃DCR(mΩ)
实施例1 80.04％ 148 34
实施例3-1 79.45％ 152 36
实施例3-2 78.25％ 154 39
实施例3-3 77.55％ 156 40
实施例3-4 79.89％ 150 35
实施例3-5 83.43％ 143 32
由表7可知，可以通过调节第一添加剂中的含硼锂盐和负极成膜添加剂的质量百分含量的比值，调控二次电池的性能，尤其是0.002≤B1/B2≤10时，二次电池的循环性能和动力学性能能够得到明显改善。
表8
Figure PCTCN2022105827-appb-000007
Figure PCTCN2022105827-appb-000008
由表8可知，可以通过调节电解液中的电解液成膜添加剂和锂盐的质量百分含量以及电解液的粘度的相关关系，调控二次电池的性能，尤其是0.2≤E/(D1+D2)≤2.95时，二次电池的循环性能和动力学性能能够得到明显改善。
表9
项目 25℃循环600圈容量保持率(％) Tmax(℃) 25℃DCR(mΩ)
实施例1 78.23％ 145 57
实施例5-1 79.19％ 148 51
实施例5-2 82.27％ 149 45
实施例5-3 82.29％ 151 44
实施例5-4 83.76％ 154 38
实施例5-5 83.86％ 155 35
实施例5-6 83.95％ 156 32
实施例5-7 84.10％ 159 25
实施例5-8 84.24％ 159 23
由表9可知，可以通过调节正极膜层和固态电解质的相关关系，调节固态电解质对正极膜层的防护力度，从而调控二次电池的性能，尤其是5≤h1*P1/m≤250；可选地，70≤h1*P1/m≤250时，二次电池的循环性能和动力学性能能够得到明显改善。
表10
项目 25℃循环600圈容量保持率(％) Tmax(℃) 25℃DCR(mΩ)
实施例1 88.85％ 143 28
实施例6-1 87.63％ 144 32
实施例6-2 87.27％ 142 35
实施例6-3 87.12％ 143 37
实施例6-4 86.96％ 145 39
实施例6-5 86.59％ 146 42
实施例6-6 86.18％ 148 44
由表10可知，可以通过调节负极膜层和固态电解质的相关关系，调节固态电解质对负极膜层的防护力度，从而调控二次电池的性能，尤其是5≤h1*P1/m≤250；可选地，25≤h2*P2/m≤245时，二次电池的循环性能和动力学性能能够得到明显改善。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (15)

  1. 一种二次电池，包括：
    正极极片，其包括正极膜层；
    负极极片，其包括负极膜层；
    电解液；以及
    固态电解质，其设置于所述正极膜层和/或所述负极膜层的表面，所述固态电解质包括聚合物基质和第一添加剂，所述第一添加剂被配置为在所述正极膜层和/或所述负极膜层的表面形成界面膜，其中，
    所述聚合物基质的相对于所述固态电解质的总质量的质量百分含量记为A％；
    所述第一添加剂的相对于所述固态电解质的总质量的质量百分含量记为B％，
    所述二次电池满足：0.1≤B/A≤19；可选地，0.5≤B/A≤10。
  2. 根据权利要求1的二次电池，其中，
    所述二次电池满足：5≤A≤99；和/或0.1≤B≤95。
  3. 根据权利要求1或2所述的二次电池，其中，所述第一添加剂包括：
    含硼锂盐，其相对于所述固态电解质的总质量的质量百分含量记为B1％；
    负极成膜添加剂，其相对于所述固态电解质的总质量的质量百分含量记为B2％，
    其中，所述二次电池满足：0.002≤B1/B2≤10。
  4. 根据权利要求3所述的二次电池，其中，
    所述二次电池满足：0.1≤B1≤50；和/或0.1≤B2≤50。
  5. 根据权利要求3或4所述的二次电池，其中，
    所述含硼锂盐的分子式为LiBF aO bC cP d，分子式中，0≤a≤4，0≤b≤8，0≤c≤4，0≤d≤4；
    可选地，所述含硼锂盐包括四氟硼酸锂LiBF 4、双草酸硼酸锂LiBOB和双氟草酸硼酸锂LiDFOB中的一种或多种。
  6. 根据权利要求3至5中任一项所述的二次电池，其中，
    所述负极成膜添加剂包括碳酸酯类添加剂、硫酸酯类添加剂和亚硫酸酯类添加剂中的一种或多种。
  7. 根据权利要求6所述的二次电池，其中，
    所述碳酸酯类添加剂包括环状碳酸酯溶剂和/或线性碳酸酯溶剂；可选地，所述环状碳酸酯溶剂包括碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种；所述线性碳酸酯溶剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC和聚碳酸酯VA中的一种或多种；和/或
    所述硫酸酯类添加剂包括环状磺酸酯类添加剂和/或硫酸烃基酯类添加剂；可选地，所述环状磺酸酯类添加剂包括1,3-丙烷磺酸内酯PS、丙烯磺酸内酯PES、3-氟-1,3-丙磺酸内酯FPS中的一种或多种；和/或所述硫酸烃基酯类添加剂包括硫酸乙烯酯DTD、硫酸二乙酯DES和硫酸二甲酯DMS中的一种或多种；和/或
    所述亚硫酸酯类添加剂包括亚硫酸乙烯酯ES和/或乙烯基亚硫酸乙烯酯VES。
  8. 根据权利要求1至7中任一项所述的二次电池，其中，所述电解液包括：
    环状碳酸酯溶剂，其相对于所述电解液的总质量的质量百分含量记为M1％；
    线性碳酸酯溶剂，其相对于所述电解液的总质量的质量百分含量记为M2％，
    其中，所述二次电池满足：10 -3≤M1/M2≤2，优选范围0.1≤M1/M2≤1；
    可选地，1≤M1≤20；和/或50≤M2≤85。
  9. 根据权利要求8所述的二次电池，其中，
    所述环状碳酸酯溶剂包括碳酸乙烯酯EC、碳酸丙烯酯PC、碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种；和/或
    所述线性碳酸酯溶剂包括碳酸乙基烯丙酯AEC、碳酸二苯酯DPC和碳酸甲基烯丙酯MAC、聚碳酸酯VA、碳酸二乙酯DEC、碳酸甲乙酯EMC、碳酸甲丙酯MPC、碳酸乙丙酯EPC、碳酸甲丁酯MBC、乙酸甲酯MA、乙酸乙酯EA、丙酸甲酯MP和丙酸乙酯EP中的一种或多种。
  10. 根据权利要求1至9中任一项所述的二次电池，其中，所述电解液包括：
    电解液成膜添加剂，其基于所述电解液的总质量的质量百分含量记为D1％；
    锂盐，其基于所述电解液的总质量的质量百分含量记为D2％，
    所述二次电池满足：0.2≤E/(D1+D2)≤2.95，式中E表示电解液的粘度，其单位为mPa·s。
  11. 根据权利要求1至10中任一项所述的二次电池，其中，
    所述固态电解质的溶液固体质量含量和液体质量含量的百分比记为m；
    所述正极膜层的压实密度记为P1 g/cm 3
    所述正极膜层的厚度记为h1μm，
    所述二次电池满足：5≤h1*P1/m≤250。
  12. 根据权利要求1至11中任一项所述的二次电池，其中，
    所述固态电解质的溶液固体质量含量和液体质量含量的百分比记为m；
    所述负极膜层的压实密度记为P2 g/cm 3
    所述负极膜层的厚度记为h2μm，
    所述二次电池满足：25≤h2*P2/m≤245。
  13. 一种电池模块，包括如权利要求1至12中任一项所述的二次电池。
  14. 一种电池包，包括如权利要求13所述的电池模块。
  15. 一种用电装置，包括如权利要求1至12中任一项所述的二次电池、如权利要求13所述的电池模块或如权利要求14所述的电池包。
PCT/CN2022/105827 2022-07-14 2022-07-14 二次电池、电池模块、电池包和用电装置 WO2024011541A1 (zh)

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