WO2023142106A1 - 二次电池用隔膜及其制备方法、二次电池、电池模块、电池包和用电装置 - Google Patents

二次电池用隔膜及其制备方法、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2023142106A1
WO2023142106A1 PCT/CN2022/075173 CN2022075173W WO2023142106A1 WO 2023142106 A1 WO2023142106 A1 WO 2023142106A1 CN 2022075173 W CN2022075173 W CN 2022075173W WO 2023142106 A1 WO2023142106 A1 WO 2023142106A1
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Prior art keywords
lithium
conductive material
battery
weight
layer
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PCT/CN2022/075173
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English (en)
French (fr)
Inventor
童星
史松君
来佑磊
朱映华
李静如
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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 CN202280040851.1A priority Critical patent/CN117461203A/zh
Priority to PCT/CN2022/075173 priority patent/WO2023142106A1/zh
Priority to EP22908807.5A priority patent/EP4254634A1/en
Priority to US18/344,980 priority patent/US20230395938A1/en
Publication of WO2023142106A1 publication Critical patent/WO2023142106A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of secondary batteries, in particular to a separator for a secondary battery, a method for preparing the separator, and a secondary battery, a battery module, a battery pack and an electrical device including the separator.
  • lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields. Due to the great development of lithium-ion batteries, higher requirements have been put forward for their energy density, cycle performance and safety performance.
  • the lithium supplementing agent may include an inner core and an organic-inorganic shell, the inner core includes a lithium-rich compound, and the organic-inorganic shell may include a polymer and an inorganic compound containing silicon-oxygen bonds.
  • the organic-inorganic shell is coated on the surface of the inner core of the lithium supplementing agent, which can not only play a coating effect, isolate the inner core from air/oxygen, but also release the inner core after liquid injection, and the lithium-rich compound in the inner core can participate in the negative electrode
  • the film-forming reaction forms an SEI film on the surface of the negative electrode, thereby reducing the irreversible lithium consumption of the positive electrode, so the initial discharge capacity is improved.
  • the lithium-rich compound from the inner core can also act as active lithium. When the active lithium is insufficient during the cycle, the active lithium stored in the negative electrode can participate in the electrochemical reaction in time, thereby reducing the attenuation of battery capacity and prolonging battery life. .
  • the outer inorganic-organic shell will hinder the electron conduction path of the lithium-rich compound in the inner core, making it difficult for the lithium-rich oxide to participate in the oxidation reaction during the formation process. low efficiency.
  • the lithium-supplementing agent layer is coated on the surface of the separator substrate layer, which will inevitably cause the gaps in the separator substrate to be blocked, hindering the migration of lithium ions in the separator.
  • the organic-inorganic shell on the surface of the lithium replenishing agent swells/dissolves under the action of the electrolyte, and the lithium ions in the inner core are gradually released so as to control the lithium replenishing rate, while methyl orthosilicate, ethyl orthosilicate, Substances such as propyl orthosilicate will also dissolve, increasing the viscosity of the electrolyte, thereby hindering the migration of lithium ions in the electrolyte.
  • the composite separator in the prior art still needs to be improved in terms of improving the utilization efficiency of the lithium supplementing agent and at the same time fully ensuring the migration of lithium ions inside the battery.
  • the purpose of the present application is to provide a secondary battery separator whose utilization efficiency of a lithium supplementing agent is significantly improved, and the migration rate of lithium ions is also significantly improved, thereby improving the secondary battery using the separator.
  • the first coulombic efficiency of the secondary battery and reduce the attenuation of battery capacity.
  • the present application provides a secondary battery separator, which includes:
  • the nanofiber layer includes a lithium supplementing agent, a polymer, and an optional conductive material, wherein, relative to the total weight of the nanofiber layer, the content of the lithium supplementing agent is 30.0 to 50.0% by weight, and the polymer
  • the content of the conductive material is 50.0-70.0% by weight, and the content of the conductive material is 0-5.0% by weight.
  • a nanofibrous layer comprising a lithium-replenishing agent, a polymer, and an optional conductive material on one surface of the separator substrate layer as a lithium-replenishing agent layer
  • the lithium replenishing agent is slowly released from the nanofiber layer, and participates in the film-forming reaction of the negative electrode, playing the role of replenishing lithium.
  • the nanofiber layer as the lithium supplement layer has a unique nanofiber structure, which can fully ensure the continuous lithium ion migration of the lithium supplement in the nanofiber layer.
  • the polymer in the nanofibrous layer works synergistically with the lithium supplementing agent, which can improve the utilization efficiency of the lithium supplementing agent, thereby increasing the initial discharge capacity of the battery and reducing the attenuation of the battery capacity.
  • the optional conductive material in the nanofibrous layer can increase the electronic pathway of the lithium-supplementing agent in the nanofiber layer, further improve the utilization efficiency of the lithium-supplementing agent, thereby further improving the initial discharge capacity of the battery and further reducing the attenuation of the battery capacity.
  • the conductive material includes a zero-dimensional conductive material and an optional one-dimensional conductive material, and relative to the total weight of the nanofiber layer, the content of the zero-dimensional conductive material is 1.0 to 5.0% by weight , the content of the one-dimensional conductive material is 0-0.3% by weight.
  • the zero-dimensional conductive material has a particle size of 30-50 nm.
  • the zero-dimensional conductive material is one or more selected from carbon black, acetylene black and Ketjen black.
  • the one-dimensional conductive material has an aspect ratio of 500-1000.
  • the one-dimensional conductive material is carbon nanotubes, which may be single-armed nanotubes, multi-armed nanotubes or a combination of both.
  • the lithium replenishing agent is selected from Li 2 C 2 O 4 , C 4 BLiO 8 , Li 15 Si 4 , Li 4 Sn, Li 2 NiO 2 , LiF, Li 2 TiO 3 , Li 2 CrO 4. Li 2 Cr 2 O 7 , Li 4 SiO 4 , Li 2 SiO 3 , Li 3 AsO 4 , Li 2 SeO 4 , Li 2 SeO 3 , LiVO 3 , LiAlO 2 , Li 3 PO 4 , Li 2 B 8 O 13.
  • Li 2 B 4 O 7 , LiBO 2 , Li 3 AlF 6 , Li 2 SnF 6 and LiAsF 6 one of Li 2 NiO 2 , Li 4 Sn and LiAsF 6 can be selected or more.
  • the particle size of the lithium supplement agent is 50-200 nm, optionally 80-150 nm.
  • the amount of the lithium-supplementing agent is 40-100 parts by weight, optionally 60-80 parts by weight.
  • the amount of the zero-dimensional conductive material is 1-12.5 parts by weight; and the amount of the one-dimensional conductive material is 0.15-0.75 parts by weight.
  • the polymer is one or more selected from polyvinylidene chloride, polyimide, polyacrylonitrile and polystyrene.
  • the nanofibers in the nanofiber layer have a diameter of 100-500 nm, optionally 200-250 nm.
  • the thickness of the nanofiber layer is 1.0-5.0 ⁇ m, optionally 1.5-2.5 ⁇ m.
  • the porosity of the nanofiber layer is 80% or more.
  • the present application provides a method for preparing a separator for a secondary battery, comprising:
  • the dispersion is attached to one surface of the substrate layer by electrospinning to form a nanofiber layer
  • the content of the lithium supplementing agent is 30.0-50.0% by weight
  • the content of the polymer is 50.0-70.0% by weight
  • the The content of the conductive material is 0 to 5% by weight.
  • the polymer solution has a solid content of 20-40% by weight, optionally 20-25% by weight.
  • the thickness of the nanofiber layer is 1.0-5.0 ⁇ m, optionally 1.5-2.5 ⁇ m.
  • the present application provides a secondary battery comprising:
  • the nanofiber layer is disposed on the surface of the substrate layer facing the positive electrode.
  • the present application provides a battery module, which includes the secondary battery of the third aspect of the present application.
  • the present application provides a battery pack, which includes the battery module of the fourth aspect of the present application.
  • the present application provides an electric device, which includes at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, and the battery pack of the fifth aspect of the present application.
  • the separator for the secondary battery of the present application by providing the nanofiber layer comprising lithium replenishing agent, polymer and optional conductive material as the lithium replenishing agent layer in the form of nanofibrous layer possessing high porosity, significantly improved
  • the utilization efficiency of the lithium-supplementing agent also increases the migration rate of lithium ions, thereby significantly improving the first coulombic efficiency of the secondary battery using the separator and reducing the attenuation of battery capacity.
  • FIG. 1 is a schematic diagram of a diaphragm according to an embodiment of the present application.
  • Fig. 2 is a schematic diagram of nanofibers in a nanofiber layer of a separator according to an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack according to one embodiment of the present application shown in FIG. 6 .
  • FIG. 8 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and 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 and may be combined arbitrarily, ie 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, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, 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" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the present application proposes a separator for a secondary battery, which includes:
  • the nanofiber layer includes a lithium supplementing agent, a polymer, and an optional conductive material, wherein, relative to the total weight of the nanofiber layer, the content of the lithium supplementing agent is 30.0 to 50.0% by weight, and the polymer
  • the content of the conductive material is 50.0-70.0% by weight, and the content of the conductive material is 0-5.0% by weight.
  • the present application includes a lithium supplementing agent, a polymer, and an optional conductive material on one surface of the substrate layer (61).
  • the fiber layer (62) is used as a lithium supplementing agent layer to provide a separator (6) for a secondary battery.
  • the lithium-replenishing agent is slowly released from the nanofiber layer during liquid injection and formation, thereby playing the role of lithium-replenishment.
  • the released lithium-supplementing agent can participate in the film-forming reaction of the negative electrode, forming an SEI film on the surface of the negative electrode, reducing the irreversible lithium consumption of the positive electrode, thereby significantly improving the initial discharge capacity of the battery.
  • the active lithium stored in the negative electrode can participate in the electrochemical reaction in time to reduce the attenuation of the battery capacity.
  • the nanofiber layer has a nanofiber structure formed of nanofibers ( 620 ) shown in FIG. 2 , so the porosity is quite high.
  • the polymer and the lithium-supplementing agent act synergistically, which can improve the utilization efficiency of the lithium-supplementing agent, thereby increasing the initial discharge capacity of the battery, improving the first Coulombic efficiency of the battery, reducing the attenuation of the battery capacity, and improving the battery life. Cycle performance, prolong battery life.
  • the polymer (64) in the nanofibrous layer can play a protective role, avoiding the lithium replenishing agent (63) in the nanofibrous layer from being invalidated by the environment; the polymer (64) passes Partial swelling can ensure the slow release of the lithium supplement (63).
  • the nanofiber layer includes a conductive material (for example, a zero-dimensional conductive material (651) and a one-dimensional conductive material (652) as shown in Figure 2)
  • a conductive material for example, a zero-dimensional conductive material (651) and a one-dimensional conductive material (652) as shown in Figure 2)
  • the electronic pathway of the lithium supplement can further improve the utilization efficiency of the lithium supplement, thereby further improving the initial discharge capacity of the battery, greatly improving the first Coulombic efficiency of the battery, and further reducing the attenuation of the battery capacity, greatly improving the cycle performance of the battery and extending the battery life. Battery Life.
  • the reaction product of the lithium-supplementing agent (63) is still wrapped inside the polymer nanofiber (620), which can improve the strength of the nanofiber (620) and play a self-supporting role.
  • the nanofiber layer as the lithium supplement layer does not contain substances that affect the viscosity of the electrolyte and other physical properties, avoiding the adverse effects of the dissolution of such substances on the ion migration in the electrolyte, thereby fully ensuring The kinetic performance of the battery.
  • the content of the lithium supplementing agent is 30.0-50.0% by weight
  • the content of the polymer is 50.0-70.0% by weight
  • the content of the conductive material is The content is 0 to 5.0% by weight.
  • the conductive material may include a zero-dimensional conductive material and optionally a one-dimensional conductive material.
  • the zero-dimensional conductive material (651) is dispersed inside the nanofiber (620), fully mixed with the lithium supplementing agent (63), and can provide point-to-point electronic paths. Therefore, the zero-dimensional conductive material (651) can promote the migration of electrons in the nanofiber layer, increase the electron path of the lithium supplementing agent, and thereby realize the improvement of the utilization efficiency of the lithium supplementing agent.
  • the conductive material includes a one-dimensional conductive material, as shown in FIG.
  • the one-dimensional conductive material (652) can be partially exposed outside the nanofiber (620), and the part of the one-dimensional conductive material (652) exposed to the outside will not be exposed.
  • Polymer (64) coating when the separator is applied to a secondary battery in such a way that the nanofiber layer is disposed on the positive electrode-facing surface of the base material layer, the one-dimensional conductive material (652) can not only further promote the migration of electrons in the nanofiber layer, but also its The partially exposed part can also additionally promote the electron transfer between the nanofibrous layer and the cathode active material, thereby further improving the utilization efficiency of the lithium supplementation agent.
  • the content of the zero-dimensional conductive material may be 1.0-5.0% by weight, and the content of the one-dimensional conductive material may be 0-0.3% by weight.
  • the zero-dimensional conductive material may have a particle size of 30-50 nm.
  • the zero-dimensional conductive material has a particle size within the above range, more point-to-point electronic paths can be realized under the same addition amount, thereby further improving the utilization efficiency of the lithium supplement.
  • the zero-dimensional conductive material can play the role of providing point-to-point electronic pathways as described above, there is no specific limitation on the type of zero-dimensional conductive material, and those skilled in the art can choose according to actual needs.
  • the zero-dimensional conductive material may be one or more selected from carbon black, acetylene black and Ketjen black.
  • the one-dimensional conductive material may have an aspect ratio of 500-1000.
  • the one-dimensional conductive material has an aspect ratio within the above range, it can be ensured that the one-dimensional conductive material can fully exert the above-mentioned additional role of promoting electron migration between the nanofibrous layer and the positive electrode active material, thereby further improving the utilization of the lithium supplementing agent efficiency.
  • the one-dimensional conductive material can play the above-mentioned additional functions, there is no specific limitation on the type of one-dimensional conductive material, and those skilled in the art can choose according to actual needs.
  • the one-dimensional conductive material may be carbon nanotubes, which may be single-armed nanotubes, multi-armed nanotubes or a combination of both. Since carbon nanotubes have good electrical conductivity and small diameter, they can avoid occupying too much volume.
  • the lithium supplement agent is selected from Li 2 C 2 O 4 , C 4 BLiO 8 , Li 15 Si 4 , Li 4 Sn, Li 2 NiO 2 , LiF, Li 2 TiO 3 , Li 2 CrO 4. Li 2 Cr 2 O 7 , Li 4 SiO 4 , Li 2 SiO 3 , Li 3 AsO 4 , Li 2 SeO 4 , Li 2 SeO 3 , LiVO 3 , LiAlO 2 , Li 3 PO 4 , Li 2 B 8 O 13.
  • Li 2 B 4 O 7 , LiBO 2 , Li 3 AlF 6 , Li 2 SnF 6 and LiAsF 6 one of Li 2 NiO 2 , Li 4 Sn and LiAsF 6 can be selected or more.
  • the particle size of the lithium supplement agent is 50-200 nm, optionally 80-150 nm.
  • the lithium supplementing agent has a particle size within the above range, it can optimize the nanofiber diameter, so that the nanofiber layer has an optimized structure, not only can more effectively avoid blocking the gaps in the substrate layer, but also make the The separator has better wettability and liquid retention to the electrolyte, and better promotes the migration of lithium ions of the lithium replenishing agent in the nanofiber layer.
  • the amount of the lithium-supplementing agent is 40-100 parts by weight, optionally 60-80 parts by weight.
  • the relative amount of the lithium-supplementing agent relative to the polymer is within the above range, it can be beneficial to the synergistic effect between the polymer and the lithium-supplementing agent, ensuring that the polymer can completely cover the lithium-supplementing agent and play a sufficient protective role , and at the same time, it can ensure the slow release of the lithium supplement, thereby fully improving the utilization efficiency of the lithium supplement.
  • the amount of the zero-dimensional conductive material is 1-12.5 parts by weight; and the amount of the one-dimensional conductive material is 0.15-0.75 parts by weight.
  • the dosage of the lithium-supplementing agent can be optimized while ensuring good electronic conductance and fully improving the utilization efficiency of the lithium-supplementing agent.
  • the polymer is one or more selected from polyvinylidene chloride, polyimide, polyacrylonitrile and polystyrene.
  • the nanofibers in the nanofiber layer have a diameter of 100-500 nm, optionally 200-250 nm.
  • the formed nanofiber layer can have a higher porosity, which can not only more effectively avoid clogging the voids of the substrate layer, but also improve the wettability and retention of the separator to the electrolyte.
  • the liquid property is better, and it can better promote the continuous lithium ion migration of the lithium replenishing agent in the nanofiber layer.
  • the diameter of the nanofiber can be adjusted by adjusting the extrusion speed of the dispersion liquid for electrospinning, the distance between the spinning head and the receiving end plate, the distance between the spinning head and the receiving end plate, The process parameters such as the voltage between the end plates are controlled, and those skilled in the art can select according to actual needs.
  • the thickness of the nanofiber layer is 1.0-5.0 ⁇ m, optionally 1.5-2.5 ⁇ m.
  • the thickness of the nanofiber layer can be controlled by adjusting the spinning time during the electrospinning process for preparing the nanofiber layer, and those skilled in the art can choose according to actual needs.
  • the porosity of the nanofiber layer is above 80%.
  • the porosity of the nanofiber layer reaches more than 80%, it can not only fully avoid the clogging of the gaps in the substrate layer, but also improve the wettability and liquid retention of the separator to the electrolyte, ensuring the continuous lithium supplementation in the nanofiber layer. Lithium ion migration.
  • the present application also provides a method for preparing a separator for a secondary battery, comprising:
  • the dispersion is attached to one surface of the substrate layer by electrospinning to form a nanofiber layer
  • the content of the lithium supplementing agent is 30.0-50.0% by weight
  • the content of the polymer is 50.0-70.0% by weight
  • the The content of the conductive material is 0 to 5% by weight.
  • the preparation method of the present application can efficiently prepare the secondary battery separator of the first aspect of the present application.
  • the solid content of the polymer solution may be 20-40% by weight, optionally 20-25% by weight.
  • the dispersion obtained by adding the polymer solution to the lithium-supplementing agent or the blend of the lithium-supplementing agent and the conductive material and dispersing at a high speed will be suitable for the electrospinning process, and It can ensure that the diameter of nanofibers produced by electrospinning is more uniform, the distribution of lithium supplementation agent and/or conductive material and the distribution of pores in nanofiber layer are more uniform, and the lithium supplementation effect of lithium supplementation agent and the performance of diaphragm can be stabilized .
  • the thickness of the nanofiber layer may be 1.0-5.0 ⁇ m, optionally 1.5-2.5 ⁇ m.
  • the thickness of the nanofiber layer can be adjusted by adjusting the process parameters of the electrospinning step, and those skilled in the art can choose according to actual needs.
  • the present application also provides a secondary battery, which includes:
  • the nanofiber layer is disposed on the surface of the substrate layer facing the positive electrode.
  • the present application also provides a battery module, which includes the above-mentioned secondary battery of the present application.
  • the present application also provides a battery pack, which includes the above-mentioned battery module of the present application.
  • the present application also provides an electric device, which includes at least one of the above-mentioned secondary battery of the present application, the above-mentioned battery module of the present application, and the above-mentioned battery pack of the present application.
  • a nanofibrous layer comprising a lithium supplementing agent, a polymer, and an optional conductive material is provided on one surface of the substrate layer as a lithium supplementing agent layer.
  • the lithium replenishing agent can be slowly released from the nanofiber layer during liquid injection and formation, and participate in the film-forming reaction of the negative electrode to play the role of lithium replenishment.
  • the nanofiber layer has a high porosity, which can effectively avoid blocking the pores of the substrate layer, and at the same time improve the wettability and liquid retention of the separator to the electrolyte, thereby fully ensuring the continuous lithium supplementation in the nanofiber layer. Lithium ion migration.
  • the polymer in the nanofibrous layer works synergistically with the lithium-supplementing agent to improve the utilization efficiency of the lithium-supplementing agent, thereby increasing the initial discharge capacity of the battery and reducing the attenuation of the battery capacity.
  • the optional conductive material in the nanofibrous layer can increase the electronic pathway of the lithium-supplementing agent in the nanofiber layer, further improve the utilization efficiency of the lithium-supplementing agent, thereby further increasing the initial discharge capacity of the battery and further reducing the attenuation of the battery capacity.
  • the product after the lithium supplementation reaction is still wrapped inside the polymer nanofiber, which can improve the strength of the nanofiber and play a self-supporting role.
  • the nanofiber layer used as the lithium supplement layer does not contain substances that affect the viscosity of the electrolyte and other physical properties, avoiding the adverse effects of the dissolution of such substances on the ion migration in the electrolyte, thereby fully ensuring the kinetic performance of the battery .
  • a secondary battery is provided.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the diaphragm is arranged between the positive pole piece and the negative pole piece, mainly to prevent the short circuit of the positive and negative poles, and at the same time allow ions to pass through.
  • the positive electrode sheet may include a positive electrode collector and a positive electrode film layer disposed on at least one surface of the positive electrode collector.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the above-mentioned positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid Formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET ethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the above-mentioned positive electrode film layer includes a positive electrode active material
  • the positive electrode active material includes, but is not limited to, lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, silicon Lithium iron oxide, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium titanate, etc.
  • the positive electrode active material includes, but is not limited to, lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, silicon Lithium iron oxide, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium titan
  • the positive film layer also optionally includes a binder.
  • a binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene One or more of meta-copolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene
  • meta-copolymer tetrafluoroethylene-hexafluoro
  • the positive film layer also optionally includes a conductive agent.
  • a conductive agent there is no specific limitation on the type of conductive agent, which can be selected by those skilled in the art according to actual needs.
  • the conductive agent used in the positive film layer may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared according to methods known in the art.
  • the positive electrode active material, conductive agent and binder can be dispersed in a solvent (such as N-methylpyrrolidone (NMP)) to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, After drying, cold pressing and other processes, the positive electrode sheet is obtained.
  • NMP N-methylpyrrolidone
  • the negative electrode sheet may include a negative electrode collector and a negative electrode film layer disposed on at least one surface of the negative electrode collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the above-mentioned negative electrode current collector can be a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode film layer includes a negative electrode active material.
  • the negative electrode active material can use the negative electrode active material commonly used in the art to prepare the secondary battery negative pole, as the negative electrode active material, can enumerate artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate etc.
  • the silicon-based material can be selected from one or more of elemental silicon, silicon-oxygen compounds (such as silicon oxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material can be selected from one or more of simple tin, tin oxide compounds and tin alloys.
  • the negative electrode film layer may also include optional binders, optional conductive agents and other optional additives.
  • the conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), One or more of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • CMC-Na sodium carboxymethylcellulose
  • the negative electrode sheet can be prepared according to methods known in the art.
  • the negative electrode active material, conductive agent, binder and any other components can be dispersed in a solvent (such as N-methylpyrrolidone (NMP) or deionized water) to form a uniform negative electrode slurry; the negative electrode slurry
  • NMP N-methylpyrrolidone
  • the material is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet is obtained.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • electrolytes can be liquid, gel or all solid.
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonimide ( LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium difluorooxalate borate (LiBOB), lithium difluorophosphate (LiPO 2 One or more of F 2 ), lithium difluorooxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiFSI lithium bisfluorosulfonimide
  • LiTFSI lithium bistrifluorome
  • the solvent may be selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), carbonic acid Dimethyl Carbonate (DMC), Dipropyl Carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Butylene Carbonate (BC), Methyl Formate (MF), Methyl Acetate (MA ), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), butyric acid
  • FEC fluoroethylene carbonate
  • EC ethylene carbonate
  • PC propylene carbonate
  • EMC diethyl carbonate
  • DMC Dimethyl Carbonate
  • DPC Dipropyl Carbonate
  • MPC Methyl Propyl Carbon
  • additives are optionally included in the electrolyte.
  • the electrolyte may include negative electrode film-forming additives, positive electrode film-forming additives, additives for improving battery overcharge performance, additives for improving battery high-temperature performance, additives for improving battery low-temperature performance, and the like.
  • the separator separates the positive and negative pole pieces, preventing short circuits inside the battery while allowing active ions to move across the membrane between the positive and negative electrodes.
  • the separator for a secondary battery of the present application as described above is used, which is provided on one surface of the base layer with a lithium-supplementing agent, a polymer and An optional nanofibrous layer of conductive material acts as a lithium supplementary layer.
  • any known substrate layer with good chemical stability and mechanical stability can be used.
  • any known porous structure film for secondary batteries may be used as the base material layer of the secondary battery separator used in the present application.
  • the substrate layer can be selected from glass fiber film, non-woven fabric film, polyethylene (PE) film, polypropylene (PP) film, polyvinylidene fluoride film, and one or more of them One or more of the multilayer composite substrate layers.
  • a polyolefin microporous membrane commonly used in the art can be used as the substrate layer of the secondary battery separator used in the present application.
  • a nanofiber layer with high porosity can be formed on one surface of the substrate layer as a lithium supplementing layer by using an electrospinning process.
  • the diameter of the nanofiber can be controlled to be 100-500 nm, optionally 200-250 nm; by adjusting the spinning time, the thickness of the nanofiber layer can be controlled to be 1.0-5.0 ⁇ m, optionally 1.5-2.5 ⁇ m.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the nanofiber layer serving as the lithium-supplementing layer faces the surface of the positive electrode
  • the substrate layer faces the surface of the negative electrode.
  • the secondary battery may include an outer package.
  • 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 case, such as a hard plastic case, aluminum case, steel case, and the like.
  • 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 plastic include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • FIG. 3 shows a square-shaped secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing chamber. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 5 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • a secondary battery, a battery module, or a battery pack can be used as a power source of a power consumption device, and can also be used as an energy storage unit of the power consumption device.
  • Electric devices may include, 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, electric golf golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • secondary batteries, battery modules, or battery packs can be selected according to their usage requirements.
  • FIG. 8 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • the electric device may be a mobile phone, a tablet computer, a notebook computer, and the like.
  • the electrical device is usually required to be light and thin, and a secondary battery can be used as a power source.
  • a polyethylene microporous film having a thickness of about 7 ⁇ m was used as the base material layer of the secondary battery separator of the present application.
  • a nanofibrous layer including lithium supplementation agent, polymer and optional conductive material is formed on one surface of the substrate layer.
  • Dispersions for electrospinning were prepared as follows.
  • a polymer e.g., one or more of polyvinylidene chloride, polyimide, polyacrylonitrile, and polystyrene
  • a solvent e.g., N-methylpyrrolidone (NMP), dimethylethyl One or more of amide (DMAC) and dimethylformamide (DMF)
  • NMP N-methylpyrrolidone
  • DMAC dimethylethyl One or more of amide
  • DMF dimethylformamide
  • Use lithium supplements as component B Alternatively, the lithium supplementing agent and the conductive material are stirred and mixed under an inert gas range to form a uniformly mixed blend as component B. Add component A to component B, and stir at a high speed of about 1000-1500 rpm/min for about 1-1.5 hours until a uniform dispersion for electrospinning is formed.
  • the dispersion liquid obtained in the above steps is sprayed on the substrate layer through a spinning head with an inner diameter of 1-2mm.
  • the spraying thickness is 1.0-5.0 ⁇ m, and a nanofiber layer directly attached thereon is formed on one surface of the substrate layer.
  • the content of the lithium supplementing agent is about 30.0-50.0% by weight
  • the content of the polymer is about 50.0-70.0% by weight
  • the content of the conductive material is about 0-50.0% by weight. 5% by weight.
  • the positive electrode active material Ni 5 Co 2 Mn 3 (NCM523, Beijing Dangsheng Material Technology Co., Ltd.), conductive carbon (Super-P-Li, TIMCAL company), binder polyvinylidene fluoride (PVDF) (5130, the United States Solvay) was added into N-methylpyrrolidone (NMP) at a weight ratio of 97:1.5:1.5 and fully stirred to uniformly mix to obtain a positive electrode slurry with a solid content of 72%.
  • NMP N-methylpyrrolidone
  • NMP N-methylpyrrolidone
  • the positive electrode slurry is uniformly coated on the aluminum foil with a coating amount of 0.156mg/ mm2 through an extrusion coater or a transfer coater, and dried at 100-130°C to obtain a positive electrode pole piece.
  • Negative electrode active material silicon oxide (Xinjiang Jingshuo New Material Co., Ltd.), conductive carbon (Super-P-Li, TIMCAL company), binder PVDF (5130, Solvay, USA) in a weight ratio of 95:2:3 Add it into NMP and stir well to mix evenly to obtain negative electrode slurry with a solid content of 52%.
  • the negative electrode slurry is uniformly coated on the copper foil with a coating amount of 0.106mg/ mm2 through an extrusion coater or a transfer coater, and dried at 100-130°C to obtain Negative pole piece.
  • the electrolyte used was a solution of LiPF 6 in a mixed solvent of (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC) with a volume ratio of 1:1:1 (molar concentration 1 mol/L). After formation and volume separation, a lithium-ion battery is obtained.
  • the separator with the nanofiber layer was punched into a small disc with an area S 0 , the small disc was weighed, and the weight was recorded as m 2 , and the thickness h 1 of the small disc was measured. Then, after immersing the small disc of the diaphragm in isobutanol (density ⁇ 1 ) for 0.5 hour, it was taken out and weighed, and the weight was recorded as m 3 .
  • the substrate layer without the nanofiber layer was punched into a small disc with the same area S 1 , the small disc was weighed, and the weight was recorded as m 0 , and the thickness h 0 of the small disc was measured.
  • Porosity ⁇ [(m 3 -m 2 )-(m 1 -m 0 )]/[ ⁇ 1 (h 1 -h 0 ) ⁇ S 0 ] ⁇ 100%
  • the initial charging capacity of the battery is designed to release the capacity of 75Ah.
  • To measure the discharge capacity for the first time first fully charge the battery to 4.2V with a constant current of 0.33C and constant voltage to 0.05C; after standing for 1 hour, discharge the battery with a constant current of 0.33C to 2.8V, and record the discharge capacity as the first Secondary discharge capacity C.
  • the fresh battery is charged and discharged at a rate of 0.33C at a normal temperature of 25°C, and the discharge capacity at this time is recorded as the initial capacity C 0 . Then, the battery was cycled at 1C rate charge and 1C rate discharge at room temperature 25°C, and the discharge capacity after 1800 cycles was counted as C 1 . Calculate the capacity retention rate according to the following formula:
  • the polymer polyvinylidene chloride (PVDF) was added to the NMP solvent at a mass ratio of 20:80, and stirred to form a transparent and uniform polymer solution as component A.
  • Lithium-supplementing agent Li 2 NiO 2 with a particle size of 100 nm was used as component B. Under an inert atmosphere, component A was added to component B at a mass ratio of 15:2, and stirred at a high speed of about 1000 for about 1.2 hours until a uniform dispersion was formed for electrospinning.
  • Electrospinning was carried out under the conditions of a temperature of 25° C., a humidity of 15% RH, and an applied voltage of 15 kV.
  • the above-mentioned dispersion liquid is sprayed onto one surface of a substrate layer polyethylene microporous film with a thickness of about 7 ⁇ m through a spinning head with an inner diameter of 1 mm to obtain nanofibers with a diameter of 200 nm.
  • a nanofiber layer with a thickness of about 1.5 ⁇ m was finally obtained as the lithium supplement layer.
  • the content of the lithium supplementing agent is about 30.0% by weight
  • the content of the polymer is about 70.0% by weight.
  • the porosity of the nanofibrous layer of the separator of Example 1 was measured by the test method described above.
  • a lithium ion battery was prepared using the separator of Example 1 by the method described above. Then, the first-time Coulombic efficiency and capacity retention rate of the battery prepared with the separator of Example 1 were measured by the test method described above.
  • the polymer PVDF was added to the NMP solvent at a mass ratio of 20:80 to obtain a polymer solution.
  • the content of the lithium-supplementing agent is about 40.0% by weight
  • the weight of the polymer is about 60.0% by weight.
  • the separator of Comparative Example 1 After drying the obtained composite layer including the substrate layer and the coating layer at a temperature of about 80-95° C., the separator of Comparative Example 1 was obtained.
  • the lithium-supplementing layer is a conventional coating without a porous structure.
  • the separator of Comparative Example 1 was used to prepare a lithium-ion battery, wherein when the negative electrode sheet, separator and positive electrode sheet were wound into a core, the coating of the separator was faced to the surface of the positive electrode. Then, the first-time Coulombic efficiency and capacity retention rate of the battery prepared with the separator of Comparative Example 1 were measured by the test method described above.
  • a separator and a secondary battery were prepared by substantially the same method as in Example 1, the only difference being that, in the prepared nanofibers, the content of the lithium-supplementing agent and the content of the polymer were relative to the total weight of the nanofiber layer As shown in Table 1.
  • the porosity of the nanofibrous layer of the diaphragm of Examples 2-3 and Comparative Examples 2-3, and the batteries prepared by the diaphragms of Examples 2-3 and Comparative Examples 2-3 were measured respectively The first Coulombic efficiency and capacity retention.
  • Table 1 shows the content of lithium supplementing agent and polymer content in the lithium supplementing agent layer in Examples 1-3 and Comparative Examples 1-3, as well as the measured porosity, first-time Coulombic efficiency and capacity retention.
  • the lithium-supplementing agent layer includes the same content of lithium-supplementing agent and the same content of polymer, and the only difference is that the two have a nanofiber layer structure and a coating structure respectively.
  • the polymer forming nanofibers effectively avoids the failure of the lithium-supplementing agent, and slowly releases the lithium-supplementing agent during the slow swelling process, thereby improving the initial discharge capacity of the battery and making the battery For the first time, the Coulombic efficiency was increased to more than 90%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles reached more than 83%.
  • Comparative Example 2 and Comparative Example 3 the initial discharge capacity and cycle performance of the battery did not improve.
  • the reason may be that, in Comparative Example 2 and Comparative Example 3, the content of the lithium-supplementing agent and the polymer content exceeded the ranges of 30.0-50.0% by weight and 50.0-70.0% by weight, respectively.
  • the content of the lithium-supplementing agent was too low and the content of the polymer was too high, resulting in too thick a polymer coated on the surface of the lithium-supplementing agent, which was not conducive to the extraction of lithium ions. Therefore, in Example 2, the initial discharge capacity and cycle performance of the battery deteriorated.
  • Adjust the addition amount of zero-dimensional conductive material and the amount of component A and component B, so that in the prepared nanofibers, relative to the total weight of the nanofiber layer, the content of lithium-supplementing agent, polymer and zero-dimensional conductive material is as follows: Table 2 shows.
  • Examples 4-8 because the nanofiber layer is also added with a zero-dimensional conductive material that can provide point-to-point paths, it is beneficial for electrons to flow through the nanofibers.
  • the migration within the layer increases the electronic path of the lithium supplement, thereby improving the utilization efficiency of the lithium supplement.
  • the initial discharge capacity of the battery was further improved, the initial coulombic efficiency of the battery was increased to over 91%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles reached over 85%.
  • Example 4-6 Compared with Example 7 and Example 8, in Example 4-6, the initial discharge capacity of the battery is further improved, the first Coulombic efficiency of the battery is increased to more than 92%, and the cycle performance of the battery is improved, and the cycle is 1800 cycles The final capacity retention rate reached over 87%.
  • a diaphragm and a secondary battery were prepared by substantially the same method as in Example 4, except that a one-dimensional conductive material single-armed carbon nanotube with an aspect ratio of about 800 was also added to component B, and in the prepared In the nanofibers, relative to the total weight of the nanofiber layer, the contents of the lithium-supplementing agent, the polymer, the zero-dimensional conductive material and the one-dimensional conductive material are shown in Table 3.
  • Examples 9-21 since a one-dimensional conductive material that can be partially exposed to the outside of the nanofibers is also added in the nanofibers, it can not only further promote The migration of electrons in the nanofiber layer, and its partially exposed part can additionally promote the electron migration between the nanofiber layer and the positive electrode active material, thereby further improving the utilization efficiency of the lithium supplementation agent.
  • the initial discharge capacity of the battery was improved, the initial Coulombic efficiency of the battery was maintained above 90%, and the cycle performance of the battery was greatly improved, and the capacity retention rate after 1800 cycles reached above 89%.
  • Example 13 and 14 relative to 100 parts by weight of the polymer, the content of the lithium-supplementing agent is 77 parts by weight and 62.5 parts by weight, respectively, within the preferred range of 60-80 parts by weight. As a result, compared with Example 12 in which the lithium supplementing agent content was 50 parts by weight, the capacity retention rate of the battery after 1800 cycles was improved.
  • a separator and a secondary battery were prepared by substantially the same method as in Example 4, except that the particle size of the zero-dimensional conductive material carbon black added to component B was shown in Table 4.
  • the porosity of the nanofibrous layer of the diaphragm of Examples 22 to 25, and the first Coulombic efficiency and capacity retention of the battery prepared by the diaphragm of Examples 22 to 25 were measured respectively, and the results are shown in Table 4.
  • the porosity of the nanofibrous layer of the separator of Example 4 and the first-time Coulombic efficiency and capacity retention of the battery prepared with the separator of Example 4 are also listed in Table 4.
  • Example 4 23 and 24 the particle size of the zero-dimensional conductive material is in the preferred range of 30-50nm, therefore, in the same addition More point-to-point electronic pathways can be achieved under the same amount, and at the same time, it will not have an adverse effect on the electrospinning process, thereby ensuring that the utilization efficiency of the lithium supplement is further improved.
  • the initial discharge capacity of the battery was improved, the first Coulombic efficiency of the battery was as high as 92%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles reached more than 86%.
  • a separator and a secondary battery were prepared by basically the same method as in Example 4, except that the one-dimensional conductive material single-armed carbon nanotubes whose long-diameter ratio was shown in Table 5 was added to component B.
  • the contents of lithium supplements, polymers, zero-dimensional conductive materials and one-dimensional conductive materials were 39.8%, 59%, 1% and 0.2%, respectively.
  • the aspect ratio of the one-dimensional conductive material is in the preferred range of 500-1000nm, therefore, the one-dimensional conductive material can Give full play to its additional role of promoting electron migration between the nanofiber layer and the positive electrode active material, thereby ensuring that the utilization efficiency of the lithium supplement agent is further improved.
  • the initial discharge capacity of the battery was improved, the first Coulombic efficiency of the battery was maintained above 92%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles reached above 91%.
  • a diaphragm and a secondary battery were prepared by substantially the same method as in Example 4, except that the particle size of the lithium supplementing agent was shown in Table 6.
  • the porosity of the nanofibrous layer of the diaphragm of Examples 31 to 34, and the first Coulombic efficiency and capacity retention of the battery prepared with the diaphragm of Examples 31 to 34 were measured respectively, and the results are shown in Table 6.
  • the porosity of the nanofibrous layer of the separator of Example 4 and the first-time Coulombic efficiency and capacity retention of the battery prepared with the separator of Example 4 are also listed in Table 6.
  • the particle size of the lithium-supplementing agent is in the preferred range of 50-200 nm, which plays a role in optimizing the diameter of the nanofibers, so that the nanofiber layer has a better performance. structure, so as to effectively avoid the clogging of the gaps in the substrate layer, improve the wettability and liquid retention of the separator to the electrolyte, and better promote the continuous lithium ion migration of the lithium replenishing agent in the nanofiber layer.
  • the initial discharge capacity of the battery was improved, the first coulombic efficiency of the battery was as high as 89%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles reached 82%.
  • the particle size of the lithium-supplementing agent is in a further preferred range of 80-150nm
  • the initial discharge capacity of the battery is further improved
  • the first Coulombic efficiency of the battery is as high as 90%
  • the cycle performance of the battery Further improvement, the capacity retention rate after 1800 cycles is as high as 85%.
  • a separator and a secondary battery were prepared by substantially the same method as in Example 9, except that in the electrospinning process, the inner diameter of the spinning head was adjusted so that the diameter of the nanofibers was as shown in Table 7.
  • the contents of lithium supplements, polymers, zero-dimensional conductive materials and one-dimensional conductive materials are 39.8%, 59.0%, 1.0% and 0.2%, respectively.
  • Example 35 100 81% 92% 91%
  • Example 36 200 82% 92% 92%
  • Example 37 250 82% 95% 92%
  • Example 38 300 80% 92% 91%
  • the diameter of the nanofiber layer is in the preferred range of 100 to 500 nm, so that the nanofiber layer has a better structure, thereby more effectively avoiding the void of the substrate layer. Blockage, improve the wettability and liquid retention of the separator to the electrolyte, and better promote the continuous lithium ion migration of the lithium supplement in the nanofiber layer.
  • the initial discharge capacity of the battery was greatly improved, and the initial Coulombic efficiency of the battery was as high as 91%, and the cycle performance of the battery was improved, and the capacity retention rate after 1800 cycles remained above 89%.
  • the diameter of the nanofiber is in the further preferred range of 200-250nm
  • the initial discharge capacity of the battery is further improved
  • the first Coulombic efficiency of the battery is as high as 94%
  • the cycle performance of the battery is further improved. After 1800 cycles, the capacity retention rate remains above 92%.
  • a separator and a secondary battery were prepared by substantially the same method as in Example 14, except that, in the electrospinning process, the electrospinning time was adjusted so that the thickness of the formed nanofiber layer was as shown in Table 8.
  • the porosity of the nanofibrous layer of the separator of Examples 40-43, and the first Coulombic efficiency and capacity retention of the battery prepared by the separator of Examples 40-43 were measured respectively, and the results are shown in Table 8.
  • the porosity of the nanofibrous layer of the separator of Example 14 and the first-time Coulombic efficiency and capacity retention of the battery prepared with the separator of Example 14 are also listed in Table 8.
  • the thickness of the nanofiber layer is in the preferred range of 1.0-5.0 ⁇ m, which is conducive to the inclusion of a sufficient amount of lithium supplementing agent in the nanofiber layer to play a sufficient role. Lithium supplementation without occupying too much space and adversely affecting the performance of the separator.
  • the initial discharge capacity of the battery was greatly improved, and the initial Coulombic efficiency of the battery was as high as 94%, and the cycle performance of the battery was greatly improved, and the capacity retention rate after 1800 cycles remained at 89%. %above.
  • the thickness of the nanofiber layer is in a further preferred range of 1.5-2.5 ⁇ m
  • the initial discharge capacity of the battery is further improved
  • the first Coulombic efficiency of the battery is as high as 96%
  • the cycle of the battery The performance is further improved, and the capacity retention rate after 1800 cycles is as high as 92%.
  • a separator and a secondary battery were prepared by substantially the same method as in Example 9, except that in the preparation of Component A, the formed polymer solution had a solid content as shown in Table 9.
  • the porosity of the nanofibrous layer of the diaphragm of Examples 44 to 46, and the first Coulombic efficiency and capacity retention of the battery prepared by the diaphragm of Examples 44 to 46 were measured respectively, and the results are shown in Table 9.
  • the porosity of the nanofibrous layer of the separator of Example 9 and the first-time Coulombic efficiency and capacity retention of the battery prepared with the separator of Example 9 are also listed in Table 9.
  • the solid content of the polymer solution is in the preferred range of 20-40%. Therefore, after it is added to a lithium-supplementing agent or a blend of a lithium-supplementing agent and a conductive material and dispersed at a high speed, the resulting dispersion is very suitable for the electrospinning process, thereby ensuring the diameter of the nanofibers produced by electrospinning More uniform, the distribution of the lithium supplement agent and/or the conductive material and the pore distribution of the nanofiber layer are more uniform, ensuring that the lithium supplement effect of the lithium supplement agent and the performance of the diaphragm are stabilized.
  • the initial discharge capacity of the battery is excellent, the first Coulombic efficiency of the battery is as high as 91%, and the cycle performance of the battery is further improved, and the capacity retention rate after 1800 cycles is as high as 90% or more .
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .
  • the diaphragm of the present application has a nanofiber layer comprising a lithium supplementing agent, a polymer, and an optional conductive material as a lithium supplementing agent layer, which greatly improves the utilization efficiency of the lithium supplementing agent, and greatly improves the battery life when applied to a secondary battery.
  • the initial discharge capacity improves the cycle performance of the battery and prolongs the battery life.
  • the present application is suitable for industrial applications.

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Abstract

一种二次电池（5）用隔膜（6）及其制备方法，以及包括该隔膜（6）的二次电池（5）、电池模块（4）、电池包（1）和用电装置。本申请的二次电池（5）用隔膜（6）包括基材层（61）和设置在所述基材层（61）的一个表面上的纳米纤维层（62），所述纳米纤维层（62）包括补锂剂（63）、聚合物（64）、和任选的导电材料，其中，相对于所述纳米纤维层（62）的总重量，所述补锂剂（63）的含量为30.0～50.0重量％，所述聚合物（64）的含量为50.0～70.0重量％，所述导电材料的含量为0～5.0重量％。

Description

二次电池用隔膜及其制备方法、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及二次电池技术领域，尤其是涉及一种二次电池用隔膜，该隔膜的制备方法，以及包括该隔膜的二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。
现有技术中已经将补锂剂应用于二次电池用隔膜，以形成包括补锂剂层的复合隔膜，意图提高二次电池的初始放电容量，并减少电池容量的衰减，延长电池寿命。目前，补锂剂可以包括内核和有机-无机壳层，所述内核包括富锂化合物，所述有机-无机壳层可以包括聚合物和含硅氧键的无机化合物。在补锂剂的内核表面包覆有机-无机壳层，既可以起到包覆效果，使内核与空气/氧气隔离，又可以在注液后释放内核，内核中的富锂化合物可以参与负极成膜反应，在负极表面形成SEI膜，从而减小正极的不可逆锂消耗，因此初始放电容量得以提高。同时，来自内核的富锂化合物也可以充当活性锂，当循环过程中活性锂不足时，这些储存到负极中的活性锂能够及时参与到电化学反应中，从而减少电池容量的衰减，延长电池寿命。
但是，在现有技术的核壳结构中，外层的无机-有机壳层会阻碍内核富锂化合物的电子导通路径，导致化成过程中富锂氧化物难以参与氧化反应，补锂剂的利用效率不高。此外，在复合隔膜中，补锂剂层涂覆在隔膜基材层的表面，必然导致隔膜基材的空隙被堵塞，阻碍隔膜中的锂离子迁移。而且，补锂剂表面的有机-无机壳层在电解液的作用下溶胀/溶解，内核中的锂离子逐步释放以便控制补锂速率的同时，正硅酸甲酯、正硅酸乙酯、正硅酸丙酯等物质也会溶出，使电解液的粘度增大，从而阻碍电解液中的锂离子迁移。
因此，现有技术的复合隔膜在提高补锂剂的利用效率、同时充分保证电池内部的锂离子迁移方面仍然有待改进。
发明内容
鉴于现有技术中存在的上述问题，本申请的目的在于提供一种补锂剂的利用效率显著 提高、并且锂离子的迁移速率也显著提高的二次电池用隔膜，从而提高使用该隔膜的二次电池的首次库伦效率，并且减少电池容量的衰减。
为了实现上述目的，在一方面，本申请提供一种二次电池用隔膜，其包括：
基材层；和
设置在所述基材层的一个表面上的纳米纤维层，
所述纳米纤维层包括补锂剂、聚合物、和任选的导电材料，其中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5.0重量％。
由此，通过在隔膜基材层的一个表面上设置包括补锂剂、聚合物和任选的导电材料的纳米纤维层作为补锂剂层，本申请的隔膜在应用于二次电池时，在注液化成时，补锂剂从纳米纤维层缓慢地释放，并参与负极成膜反应，起到补锂作用。更重要的是，在本申请的二次电池用隔膜中，作为补锂剂层的纳米纤维层具有独特的纳米纤维结构，能够充分保证纳米纤维层中补锂剂持续的锂离子迁移。纳米纤维层中的聚合物与补锂剂协同作用，能够提高补锂剂的利用效率，从而提高电池的初始放电容量，并且减少电池容量的衰减。纳米纤维层中任选的导电材料能够增加纳米纤维层内补锂剂的电子通路，进一步提高补锂剂的利用效率，从而进一步提高电池的初始放电容量，并且进一步减少电池容量的衰减。
在任意实施方式中，所述导电材料包括零维导电材料和任选的一维导电材料，并且相对于所述纳米纤维层的总重量，所述零维导电材料的含量为1.0～5.0重量％，所述一维导电材料的含量为0～0.3重量％。
在任意实施方式中，零维导电材料具有30～50nm的粒径。可选地，所述零维导电材料是选自炭黑、乙炔黑和科琴黑中的一种或多种。
在任意实施方式中，所述一维导电材料具有500～1000的长径比。可选地，所述一维导电材料是碳纳米管，可选为单臂纳米管、多臂纳米管或者二者的组合。
在任意实施方式中，所述补锂剂是选自Li 2C 2O 4、C 4BLiO 8、Li 15Si 4、Li 4Sn、Li 2NiO 2、LiF、Li 2TiO 3、Li 2CrO 4、Li 2Cr 2O 7、Li 4SiO 4、Li 2SiO 3、Li 3AsO 4、Li 2SeO 4、Li 2SeO 3、LiVO 3、LiAlO 2、Li 3PO 4、Li 2B 8O 13、Li 2B 4O 7、LiBO 2、Li 3AlF 6、Li 2SnF 6和LiAsF 6中的一种或多种，可选为Li 2NiO 2、Li 4Sn和LiAsF 6中的一种或多种。
在任意实施方式中，所述补锂剂的粒径为50～200nm，可选为80～150nm。
在任意实施方式中，相对于100重量份所述聚合物，所述补锂剂的量为40～100重量份，可选为60～80重量份。
在任意实施方式中，相对于100重量份所述补锂剂，所述零维导电材料的量为1～12.5重量份；并且所述一维导电材料的量为0.15～0.75重量份。
在任意实施方式中，所述聚合物是选自聚偏氯乙烯、聚酰亚胺、聚丙烯腈和聚苯乙烯中的一种或多种。
在任意实施方式中，所述纳米纤维层中的纳米纤维的直径为100～500nm，可选为200～250nm。
在任意实施方式中，所述纳米纤维层的厚度为1.0～5.0μm，可选为1.5～2.5μm。
在任意实施方式中，所述纳米纤维层的孔隙率为80％以上。
在第二方面，本申请提供一种二次电池用隔膜的制备方法，包括：
将聚合物溶解在溶剂中，得到聚合物溶液；
将所述聚合物溶液加入到补锂剂或者补锂剂与导电材料的共混物中，并进行高速分散，得到分散液；
将所述分散液通过静电纺丝附着于基材层的一个表面上，形成纳米纤维层，
其中，在所述纳米纤维层中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5重量％。
在任意实施方式中，所述聚合物溶液的固含量为20～40重量％，可选为20～25重量％。
在任意实施方式中，所述纳米纤维层的厚度为1.0～5.0μm，可选为1.5～2.5μm。
在第三方面，本申请提供一种二次电池，其包括：
正极；
负极；
电解质；和
本申请第一方面的隔膜，其中
所述纳米纤维层设置在所述基材层的面向所述正极的表面上。
在第四方面，本申请提供一种电池模块，其包括本申请第三方面的二次电池。
在第五方面，本申请提供一种电池包，其包括本申请第四方面的电池模块。
在第六方面，本申请提供一种用电装置，其包括本申请第三方面的二次电池、本申请第四方面的电池模块和本申请第五方面的电池包中的至少一种。
在本申请的二次电池用隔膜中，通过以具备高孔隙率的纳米纤维层的形式提供包括补锂剂、聚合物和任选的导电材料的纳米纤维层作为补锂剂层，显著提高了补锂剂的利用效 率，同时还提高了锂离子的迁移速率，从而显著提高了使用该隔膜的二次电池的首次库伦效率，并且减少了电池容量的衰减。
附图说明
图1是本申请一实施方式的隔膜的示意图。
图2是本申请一实施方式的隔膜的纳米纤维层中的纳米纤维的示意图。
图3是本申请一实施方式的二次电池的示意图。
图4是图3所示的本申请一实施方式的二次电池的分解图。
图5是本申请一实施方式的电池模块的示意图。
图6是本申请一实施方式的电池包的示意图。
图7是图6所示的本申请一实施方式的电池包的分解图。
图8是以本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包
2上箱体
3下箱体
4电池模块
5二次电池
51壳体
52电极组件
53顶盖组件
6隔膜
61基材层
62纳米纤维层
620纳米纤维
63补锂剂
64聚合物
651零维导电材料
652一维导电材料
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的二次电池用隔膜及其制备方法、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，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或 B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
本申请的一个实施方式中，本申请提出了一种二次电池用隔膜，其包括：
基材层；和
设置在所述基材层的一个表面上的纳米纤维层，
所述纳米纤维层包括补锂剂、聚合物、和任选的导电材料，其中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5.0重量％。
虽然机理尚不明确，但本申请人意外地发现：如图1所示，本申请通过在基材层(61)的一个表面上设置包括补锂剂、聚合物和任选的导电材料的纳米纤维层(62)作为补锂剂层，提供二次电池用隔膜(6)。当所述隔膜应用于二次电池时，在注液化成时，补锂剂从纳米纤维层中缓慢地释放，起到补锂作用。具体而言，释放的补锂剂可以参与负极成膜反应，在负极表面形成SEI膜，减小了正极的不可逆锂消耗，从而显著提高电池的初始放电容量。并且，当循环过程中活性锂不足时，储存到负极中的活性锂能够及时参与到电化学反应中，减少电池容量的衰减。
更重要的是，在本申请的二次电池用隔膜中，纳米纤维层具有由图2所示的纳米纤维(620)形成的纳米纤维结构，因此孔隙率相当地高。通过以这种纳米纤维层的形式来提供补锂剂层，能够有效避免对基材层孔隙的堵塞，不会阻碍锂离子的传递，进一步提高隔膜对电解液的浸润性和保液性，从而充分保证纳米纤维层内补锂剂持续的锂离子迁移。在纳米纤维层中，聚合物与补锂剂协同作用，能够提高补锂剂的利用效率，从而提高电池的初始放电容量，使电池的首次库伦效率提高，并且减少电池容量的衰减，提升电池的循环性能，延长电池寿命。具体而言，如图2所示，纳米纤维层中的聚合物(64)可以起到保护作用，避免纳米纤维层中的补锂剂(63)受环境影响而失效；聚合物(64)通过部分溶胀，可以保证补锂剂(63)的缓慢释放。当纳米纤维层中包括导电材料(例如，如图2所示的零维导电材料(651)、一维导电材料(652))时，补锂剂与导电材料的充分混合能够增加纳米纤维层内补锂剂的电子通路，进一步提高补锂剂的利用效率，从而进一步提高电池的初始放电容量，使电池的首次库伦效率大大提高，并且进一步减少电池容量的衰减，电池的循环性能大大提高，延长电池寿命。
此外，补锂剂(63)反应后的产物依旧包裹在聚合物纳米纤维(620)的内部，可以 提高纳米纤维(620)的强度，起到自支撑作用。并且，在本申请中，作为补锂剂层的纳米纤维层不含影响电解液的粘度等物理特性的物质，避免了此类物质的溶出对电解液中的离子迁移的不利影响，从而充分保证电池的动力学性能。
在本申请的二次电池用隔膜中，相对于纳米纤维层的总重量，补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5.0重量％。通过将补锂剂、聚合物和导电材料的含量分别保持在上述范围内，能够使纳米纤维层具有良好的加工性能。
在一些实施方式中，所述导电材料可以包括零维导电材料和任选的一维导电材料。如图2所示，零维导电材料(651)分散在纳米纤维(620)的内部，与补锂剂(63)充分混合，可以提供点对点电子通路。因此，零维导电材料(651)可以促进电子在纳米纤维层内的迁移，增加补锂剂的电子通路，从而实现补锂剂利用效率的提高。当导电材料包括一维导电材料时，如图2所示，一维导电材料(652)可以部分暴露于纳米纤维(620)的外部，一维导电材料(652)暴露于外部的部分不会被聚合物(64)包覆。因此，当隔膜以纳米纤维层设置在基材层的面向正极的表面上的方式应用于二次电池时，一维导电材料(652)不仅可以进一步促进电子在纳米纤维层内的迁移，而且其部分暴露的部分还可以额外地促进纳米纤维层和正极活性材料之间的电子迁移，从而进一步提高补锂剂的利用效率。
相对于所述纳米纤维层的总重量，所述零维导电材料的含量可以为1.0～5.0重量％，所述一维导电材料的含量可以为0～0.3重量％。通过将零维导电材料和任选的一维导电材料的含量分别保持在上述范围内，可以确保导电材料充分发挥上述作用，同时不会对纳米纤维层的加工性能带来不利影响。
在一些实施方式中，所述零维导电材料可以具有30～50nm的粒径。当零维导电材料具有上述范围内的粒径时，相同的添加量下可以实现更多的点对点电子通路，从而进一步提高补锂剂的利用效率。
在本申请中，只要零维导电材料能够起到上文所述的提供点对点电子通路的作用即可，对零维导电材料的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。可选地，所述零维导电材料可以是选自炭黑、乙炔黑和科琴黑中的一种或多种。
在一些实施方式中，所述一维导电材料可以具有500～1000的长径比。当一维导电材料具有上述范围内的长径比时，可以确保一维导电材料充分发挥上述的促进纳米纤维层和正极活性材料之间的电子迁移的额外作用，从而进一步提高补锂剂的利用效率。
在本申请中，只要一维导电材料能够起到上文所述的额外作用即可，对一维导电材料的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。可选地，所述一维导电材料可以是碳纳米管，可选为单臂纳米管、多臂纳米管或者二者的组合。由于碳纳米管具有良好的导电性，并且直径较小，能够避免占用过多体积。
在本申请中，只要补锂剂能够起到上文所述的补锂作用即可，对补锂剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。在一些实施方式中，所述补锂剂是选自Li 2C 2O 4、C 4BLiO 8、Li 15Si 4、Li 4Sn、Li 2NiO 2、LiF、Li 2TiO 3、Li 2CrO 4、Li 2Cr 2O 7、Li 4SiO 4、Li 2SiO 3、Li 3AsO 4、Li 2SeO 4、Li 2SeO 3、LiVO 3、LiAlO 2、Li 3PO 4、Li 2B 8O 13、Li 2B 4O 7、LiBO 2、Li 3AlF 6、Li 2SnF 6和LiAsF 6中的一种或多种，可选为Li 2NiO 2、Li 4Sn和LiAsF 6中的一种或多种。
在一些实施方式中，所述补锂剂的粒径为50～200nm，可选为80～150nm。当补锂剂具有上述范围内的粒径时，可以起到优化纳米纤维直径的作用，以使纳米纤维层具有优化的结构，不仅可以更有效地避免对基材层空隙的堵塞，还可以使隔膜对电解液的浸润性和保液性更佳，更好地促进纳米纤维层内补锂剂的锂离子迁移。
在一些实施方式中，相对于100重量份所述聚合物，所述补锂剂的量为40～100重量份，可选为60～80重量份。当补锂剂相对于聚合物的相对量处于上述范围内时，可以有利于聚合物与补锂剂之间的协同作用，保证聚合物可以将补锂剂完全包覆，起到充分的保护作用，同时可以保证补锂剂的缓慢释放，从而充分提高补锂剂的利用效率。
在一些实施方式中，相对于100重量份所述补锂剂，所述零维导电材料的量为1～12.5重量份；并且所述一维导电材料的量为0.15～0.75重量份。当零维导电材料和一维导电材料相对于补锂剂的相对量分别处于上述范围内时，可以在补锂剂用量优化的同时，保证良好的电子电导，充分提高补锂剂的利用效率。
在本申请中，只要聚合物能够加工成纳米纤维材料层并且适合用于二次电池用隔膜即可，对聚合物的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。在一些实施方式中，所述聚合物是选自聚偏氯乙烯、聚酰亚胺、聚丙烯腈和聚苯乙烯中的一种或多种。
在一些实施方式中，所述纳米纤维层中的纳米纤维的直径为100～500nm，可选为200～250nm。当纳米纤维的直径处于上述范围内时，形成的纳米纤维层可以具有更高的孔隙率，不仅可以更有效地避免对基材层空隙的堵塞，还可以使隔膜对电解液的浸润性和保液性更佳，更好地促进纳米纤维层内补锂剂持续的锂离子迁移。在本申请中，纳米纤维的 直径可以通过在制备纳米纤维层的静电纺丝工序中调整静电纺丝用分散液的挤出速度、纺丝头与接收端板间的距离、纺丝头与接收端板间的电压等工艺参数来控制，本领域技术人员可以根据实际需求进行选择。
在一些实施方式中，所述纳米纤维层的厚度为1.0～5.0μm，可选为1.5～2.5μm。当纳米纤维层的厚度处于上述范围内时，可以保证纳米纤维层中包括足够量的补锂剂，起到充分的补锂作用，同时不会占据过多的空间，对隔膜性能产生不利影响。在本申请中，纳米纤维层的厚度可以通过在制备纳米纤维层的静电纺丝工序中调整纺丝时间来控制，本领域技术人员可以根据实际需求进行选择。
在一些实施方式中，所述纳米纤维层的孔隙率为80％以上。当纳米纤维层的孔隙率达到80％以上时，不仅可以充分避免对基材层空隙的堵塞，还可以提升隔膜对电解液的浸润性和保液性，保证纳米纤维层内补锂剂持续的锂离子迁移。
本申请还提供一种二次电池用隔膜的制备方法，包括：
将聚合物溶解在溶剂中，得到聚合物溶液；
将所述聚合物溶液加入到补锂剂或者补锂剂与导电材料的共混物中，并进行高速分散，得到分散液；
将所述分散液通过静电纺丝附着于基材层的一个表面上，形成纳米纤维层，
其中，在所述纳米纤维层中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5重量％。
本申请的制备方法可以有效地制备本申请的第一方面的二次电池用隔膜。
在一些实施方式中，所述聚合物溶液的固含量可以为20～40重量％，可选为20～25重量％。当聚合物溶液的固含量处于上述范围内时，将聚合物溶液加入到补锂剂或者补锂剂与导电材料的共混物中并高速分散得到的分散液将适合于静电纺丝工序，并且可以保证静电纺丝产生的纳米纤维的直径更加均匀，补锂剂和/或导电材料的分布以及纳米纤维层的孔隙分布更加均匀，保证补锂剂的补锂作用以及隔膜的性能均得以稳定化。
在一些实施方式中，所述纳米纤维层的厚度可以为1.0～5.0μm，可选为1.5～2.5μm。在本申请中，纳米纤维层的厚度可以通过调整静电纺丝步骤的工艺参数来调整，本领域技术人员可以根据实际需求进行选择。
本申请还提供一种二次电池，其包括：
正极；
负极；
电解质；和
如上所述的本申请的二次电池用隔膜，其中
所述纳米纤维层设置在所述基材层的面向所述正极的表面上。
本申请还提供一种电池模块，其包括如上所述的本申请的的二次电池。
本申请还提供一种电池包，其包括如上所述的本申请的电池模块。
本申请还提供一种用电装置，其包括如上所述的本申请的二次电池、如上所述的本申请的电池模块和如上所述的本申请的电池包中的至少一种。
在本申请的二次电池用隔膜中，通过在基材层的一个表面上设置包括补锂剂、聚合物和任选的导电材料的纳米纤维层作为补锂剂层，本申请的隔膜在应用于二次电池时，在注液化成时，补锂剂可以从纳米纤维层缓慢地释放，并参与负极成膜反应，起到补锂作用。更重要的是，纳米纤维层具有高孔隙率，能够有效避免对基材层孔隙的堵塞，同时提高隔膜对电解液的浸润性和保液性，从而充分保证纳米纤维层中补锂剂持续的锂离子迁移。并且，纳米纤维层中的聚合物与补锂剂协同作用，能够提高补锂剂的利用效率，从而提高电池的初始放电容量，并且减少电池容量的衰减。纳米纤维层中任选的导电材料能够增加纳米纤维层内补锂剂的电子通路，进一步提高补锂剂的利用效率，从而进一步提高电池的初始放电容量，并且进一步减少电池容量的衰减。此外，补锂剂反应后的产物依旧包裹在聚合物纳米纤维的内部，可以提高纳米纤维的强度，起到自支撑作用。并且，作为补锂剂层的纳米纤维层不含影响电解液的粘度等物理特性的物质，避免了此类物质的溶出对电解液中的离子迁移的不利影响，从而充分保证电池的动力学性能。
以下适当参照附图对本申请的二次电池、电池模块、电池包和装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
正极极片可以包括正极集流体以及设置在正极集流体至少一个表面的正极膜层。作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
上述正极集流体可以采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铝箔。复合集流体可以包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可以通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
上述正极膜层包括正极活性材料，正极活性材料包括，但不限于钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂、钛酸锂等。正极活性材料可以使用这些中的一种或几种。
正极膜层还可选地包括粘结剂。但对粘结剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的一种或几种。
正极膜层还可选地包括导电剂。但对导电剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，用于正极膜层的导电剂可以选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或几种。
正极极片的制备可以根据本领域已知的方法来制备。作为示例，可以将正极活性材料、导电剂和粘结剂分散于溶剂(例如N-甲基吡咯烷酮(NMP))中，形成均匀的正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，得到正极极片。
[负极极片]
负极极片可以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，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。
上述负极集流体可以采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可以包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可以通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在本申请的二次电池中，负极膜层包括负极活性材料。所述负极活性材料可以使用本领域常用的用于制备二次电池负极的负极活性材料，作为负极活性材料，可列举出人造石 墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物(例如氧化亚硅)、硅碳复合物、硅氮复合物以及硅合金中的一种或几种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的一种或几种。
本申请的二次电池中，负极膜层还可包含可选的粘结剂、可选的导电剂和其他可选的助剂。
作为示例，导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或几种。
作为示例，粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或几种。
其他可选助剂例如是增稠剂(如羧甲基纤维素钠(CMC-Na))等。
负极极片的制备可以根据本领域已知的方法来制备。作为示例，可以将负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如N-甲基吡咯烷酮(NMP)或去离子水)中，形成均匀的负极浆料；将负极浆料涂覆在负极集流上，经烘干、冷压等工序后，得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
作为示例，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。
作为示例，溶剂可选自氟代碳酸乙烯酯(FEC)、碳酸亚乙酯(EC)、碳酸亚丙基酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
在一些实施方式中，电解质中还可选地包括添加剂。例如，电解质中可以包括负极成膜添加剂、正极成膜添加剂、改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
[隔膜]
隔膜将正极极片与负极极片隔开，防止电池内部发生短路，同时使得活性离子能够穿过隔膜在正负极之间移动。在本申请的二次电池中，作为发挥上述作用的隔膜，使用如上文所述的本申请的二次电池用隔膜，其在基材层的一个表面上设置有包括补锂剂、聚合物和任选的导电材料的纳米纤维层作为补锂层。
本申请对基材层的种类没有特别的限制，可以使用任意公知的具有良好的化学稳定性和机械稳定性的基材层。在一些实施方式中，可以使用任意公知的用于二次电池的多孔结构膜作为用于本申请的二次电池用隔膜的基材层。例如，基材层可以选自玻璃纤维薄膜、无纺布薄膜、聚乙烯(PE)薄膜、聚丙烯(PP)薄膜、聚偏二氟乙烯薄膜、以及包含它们中的一种或两种以上的多层复合基材层中的一种或几种。在一些实施方式中，可以使用本领域常用的聚烯烃微孔膜作为用于本申请的二次电池用隔膜的基材层。
可以通过本申请的制备方法，利用静电纺丝工序在基材层的一个表面上形成具有高孔隙率的纳米纤维层作为补锂层。在制备纳米纤维层的静电纺丝工序中，通过调整静电纺丝用分散液的挤出速度、纺丝头与接收端板间的距离、纺丝头与接收端板间的电压等工艺参数，可以将纳米纤维的直径控制为100～500nm，可选为200～250nm；通过调整纺丝时间，可以将纳米纤维层的厚度控制为1.0～5.0μm，可选为1.5～2.5μm。
在一些实施方式中，正极极片、负极极片和隔膜可以通过卷绕工艺或叠片工艺制成电极组件。在本申请中，组装电极组件时，将作为补锂层的纳米纤维层面向正极表面，将基材层面向负极表面。
在一些实施方式中，二次电池可以包括外包装。该外包装可以用于封装如上所述的电极组件及电解液。
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(PP)、聚对苯二甲酸丁二醇酯(PBT)以及聚丁二酸丁二醇酯(PBS)等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图3是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图4，外包装可包括壳体51和盖板53。其中，壳体51可包 括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于开口，以封闭容纳腔。正极极片、负极极片和隔膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图5是作为一个示例的电池模块4。参照图5，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，所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本领域技术人员可以根据电池包的应用和容量进行选择。
图6和图7是作为一个示例的电池包1。参照图6和图7，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。二次电池、电池模块、或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。用电装置可以包括，但不限于移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
作为用电装置，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8是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的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
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
隔膜的制备
使用厚度为约7μm的聚乙烯微孔薄膜作为本申请的二次电池用隔膜的基材层。通过静电纺丝工序，在基材层的一个表面上形成包括补锂剂、聚合物和任选的导电材料的纳米纤维层。用于静电纺丝的分散液制备如下。
将聚合物(例如，聚偏氯乙烯、聚酰亚胺、聚丙烯腈和聚苯乙烯中的一种或多种)溶解于溶剂(例如，N-甲基吡咯烷酮(NMP)、二甲基乙酰胺(DMAC)和二甲基甲酰胺(DMF)中的一种或多种)中，搅拌形成透明均匀的聚合物溶液作为组分A。组分A的固含量为约20～25重量％。使用补锂剂作为组分B。另外可选地，将补锂剂和导电材料在惰性气体范围下进行搅拌混合，形成均匀混合的共混物作为组分B。将组分A加入到组分B中，以约1000～1500rpm/min的转速高速搅拌约1～1.5小时，直至形成均匀的用于静电纺丝的分散液。
采用静电纺丝机(ELITE，北京永康乐业科技发展有限公司)，将纺丝头与接收端板间的施加电压设定为10～20KV，将纺丝头与接收端板间的距离设定为10～30cm，在温度为20～35℃、湿度为2～40％RH的条件下，通过内径为1～2mm的纺丝头，将上述步骤中得到的分散液喷附在基材层的一个表面上，喷附厚度为1.0～5.0μm，在基材层的一个表面上形成直接附着于其上的纳米纤维层。在得到的纳米纤维层中，相对于纳米纤维层的总重量，补锂剂的含量为约30.0～50.0重量％，聚合物的含量为约50.0～70.0重量％，导电材料的含量为约0～5重量％。将得到的包括基材层和纳米纤维层的复合层在约80-95℃的温度下烘干后，得到具有纳米纤维层作为补锂层的隔膜。
电芯的制备
在本申请的实施例中，电芯的制备采用以下方法。
(1)正极极片的制备
将正极活性材料Ni 5Co 2Mn 3(NCM523，北京当升材料科技股份有限公司)、导电碳(Super-P-Li，TIMCAL公司)、粘结剂聚偏氟乙烯(PVDF)(5130，美国苏威公司)按重量比97:1.5:1.5加入到N-甲基吡咯烷酮(NMP)中并充分搅拌，以均匀混合，得到固体含 量为72％的正极浆料。通过常规的工艺，将正极浆料通过挤压涂布机或者转移涂布机，以0.156mg/mm 2的涂覆量均匀涂覆在铝箔上，并在100～130℃下烘干，得到正极极片。
(2)负极极片的制备
将负极活性材料氧化亚硅(新疆晶硕新材料有限公司)、导电碳(Super-P-Li，TIMCAL公司)、粘结剂PVDF(5130，美国苏威公司)按重量比95:2:3加入到NMP中并充分搅拌，以均匀混合，得到固体含量为52％的负极浆料。通过常规的工艺，将负极浆料通过挤压涂布机或者转移涂布机，以0.106mg/mm 2的涂覆量均匀涂覆在铜箔上，并在100～130℃下烘干，得到负极极片。
(3)电池的制备
将以上步骤中得到的正极极片/负极极片按电芯设计所需制成对应规格的尺寸。然后，将负极极片、隔膜和正极极片以隔膜的纳米纤维层面向正极表面的方式进行卷绕，得到卷芯(Jelly Roll)，然后进行装配、注液。所用电解液为LiPF 6在体积比为1:1:1的(DMC)、碳酸二乙酯(DEC)和碳酸乙烯酯(EC)的混合溶剂中的溶液(摩尔浓度1mol/L)。经化成、分容后，得到锂离子电池。
性能测试
(1)孔隙率
将具有纳米纤维层的隔膜冲成面积为S 0的小圆片，将该小圆片称重，重量记为m 2，并且测量该小圆片的厚度h 1。然后，将隔膜的小圆片在异丁醇(密度ρ 1)中浸泡0.5小时后，取出称重，重量记为m 3。将不具有纳米纤维层的基材层冲成面积同样为S 1的小圆片，将该小圆片称重，重量记为m 0，并且测量该小圆片的厚度h 0。然后，将基材层的小圆片在异丁醇(密度ρ 1)中浸泡1小时后，取出称重，重量记为m 1。根据以下公式计算纳米纤维层的孔隙率：
孔隙率＝{[(m 3－m 2)－(m 1－m 0)]/[ρ 1(h 1－h 0)×S 0]}×100％
(2)首次库伦效率
电池的首次充电容量均按照设计可释放容量75Ah。为测量首次放电容量，首先将电池采用0.33C恒流满充至4.2V，恒压至0.05C；静置1小时后，将电池采用0.33C进行恒流放电至2.8V，将放电容量记为首次放电容量C。根据以下公式计算首次库伦效率计算：
首次库伦效率＝(C/75)×100％。
(3)容量保持率
将新鲜电池以0.33C倍率在常温25℃下进行充放电，此时放电容量记为初始容量C 0。然后，将电池在以1C倍率充电和1C倍率放电在常温25℃下进行循环，循环1800圈后的放电容量计为C 1。根据以下公式计算容量保持率：
容量保持率＝(C 1/C 0)×100％。
实施例1
将聚合物聚偏氯乙烯(PVDF)按质量比20:80加入到NMP溶剂中，搅拌形成透明均匀的聚合物溶液作为组分A。将粒径为100nm的补锂剂Li 2NiO 2作为组分B使用。在惰性氛围下按质量比15:2将组分A加入到组分B中，以约1000的转速高速搅拌约1.2小时，直至形成均匀的分散液用于静电纺丝。
静电纺丝在温度为25℃、湿度为15％RH、施加电压为15kV的条件下进行。通过内径为1mm的纺丝头将上述分散液喷附在厚度为约7μm的基材层聚乙烯微孔薄膜的一个表面上，可以得到直径为200nm的纳米纤维。控制静电纺丝时间，最终得到厚度约1.5μm的纳米纤维层作为补锂剂层。在该纳米纤维层中，相对于纳米纤维层的总重量，补锂剂的含量为约30.0重量％，聚合物的含量为约70.0重量％。将得到的包括基材层和纳米纤维层的复合层在约110-130℃的温度下烘干后，得到实施例1的隔膜。
通过上文所述的测试方法，测量实施例1的隔膜的纳米纤维层的孔隙率。
通过上文所述的方法，使用实施例1的隔膜制备锂离子电池。然后，通过上文所述的测试方法，测量用实施例1的隔膜制备的电池的首次库伦效率和容量保持率。
比较例1
将聚合物PVDF按质量比20:80加入到NMP溶剂中，得到聚合物溶液。在惰性氛围下按质量比2:15将补锂剂Li 2NiO 2加入到聚合物溶液中，搅拌均匀后，进行过滤，烘干，得到被聚合物包覆的复合颗粒。将该复合颗粒加入到NMP溶剂中，混合均匀后涂覆在与实施例1中相同的基材层的一个表面上，形成厚度为约1.5μm的涂层作为补锂剂层，未形成纳米纤维结构。在该涂层中，相对于涂层的总重量，补锂剂的含量为约40.0重量％，聚合物的重量为约60.0重量％。将得到的包括基材层和涂层的复合层在约80-95℃的温度下烘干后，得到比较例1的隔膜。在比较例1的隔膜中，补锂层是常规涂层，不具备多孔结构。
通过与上文所述类似的方法，使用比较例1的隔膜制备锂离子电池，其中在将负极极 片、隔膜和正极极片卷绕成卷芯时，将隔膜的涂层面向正极表面。然后，通过上文所述的测试方法，测量用比较例1的隔膜制备的电池的首次库伦效率和容量保持率。
实施例2～3和比较例2～3
通过与实施例1中基本上相同的方法制备隔膜和二次电池，不同之处仅在于，在制备的纳米纤维中，相对于纳米纤维层的总重量，补锂剂的含量和聚合物的含量如表1所示。
通过上文所述的测试方法，分别测量实施例2～3和比较例2～3的隔膜的纳米纤维层的孔隙率，以及用实施例2～3和比较例2～3的隔膜制备的电池的首次库伦效率和容量保持率。
实施例1～3和比较例1～3中的补锂剂层中的补锂剂含量和聚合物含量以及测量得到的孔隙率、首次库伦效率和容量保持率均示于表1中。
表1
Figure PCTCN2022075173-appb-000001
从以上结果可以看出，与其中补锂层为包括补锂剂和聚合物的无孔涂层的比较例1相比，在实施例1-3中，由于在基材层上形成的包括补锂剂和聚合物的纳米纤维层孔隙率高达82％以上，避免了基材层中空隙的堵塞，并且隔膜对电解液的浸润性和保液性提升，保证了补锂剂持续的锂离子迁移。尤其是，在实施例1和比较例1中，补锂剂层中包括相同含量的补锂剂和相同含量的聚合物，区别仅在于二者分别具有纳米纤维层结构和涂层结构。在实施例1-3中，形成纳米纤维的聚合物有效地避免了补锂剂的失效，并且在缓慢溶胀的过程中使补锂剂缓慢释放，从而提高了电池的初始放电容量，使电池的首次库伦效率提高至90％以上，并且电池的循环性能得到提升，循环1800圈后的容量保持率达到83％以上。
此外，在比较例2和比较例3中，电池的初始放电容量和循环性能并没有提升。原因可能在于，在比较例2和比较例3中，补锂剂含量和聚合物含量均分别超出了30.0～50.0 重量％和50.0～70.0重量％的范围。在比较例2中，补锂剂的含量过低，聚合物的含量过高，导致补锂剂表面包覆的聚合物过厚，不利于锂离子的脱出。因此，在实施例2中，电池的初始放电容量和循环性能劣化。在比较例3中，补锂剂的含量过高，聚合物的含量过低，导致在静电纺丝过程中，补锂剂表面难以被聚合物完全包覆，导致部分补锂剂因暴露于空气而失活，无法有效提供锂离子。而且，补锂剂的含量过高时，也会对防静电纺丝工艺产生不利影响，导致产生的纳米纤维层孔隙率不够高。因此，在实施例2中，电池的初始放电容量和循环性能劣化。
实施例4～8
通过与实施例1中基本上相同的方法制备隔膜和二次电池，不同之处仅在于，组分B中加入粒径为约40nm的零维导电材料炭黑，并且将补锂剂和导电材料在惰性氛围下搅拌混合，形成均匀混合的共混物。
调节零维导电材料的添加量以及组分A和组分B的用量，使得在制备的纳米纤维中，相对于纳米纤维层的总重量，补锂剂、聚合物和零维导电材料的含量如表2所示。
通过上文所述的测试方法，分别测量实施例4～8的隔膜的纳米纤维层的孔隙率，以及用实施例4～8的隔膜制备的电池的首次库伦效率和容量保持率，结果一并示于表2中。
表2
Figure PCTCN2022075173-appb-000002
从以上结果可以看出，与实施例1-3相比，在实施例4-8中，由于纳米纤维层中还添加了能够提供点对点通路的零维导电材料，因此，有利于电子在纳米纤维层内的迁移，补锂剂的电子通路增加，从而提高了补锂剂的利用效率。在实施例4-8中，电池的初始放电容量进一步提高，电池的首次库伦效率提高到91％以上，并且电池的循环性能提升，循环1800圈后的容量保持率达到85％以上。
此外，与实施例7和实施例8相比，在实施例4-6中，电池的初始放电容量进一步提高，电池的首次库伦效率提高到92％以上，并且电池的循环性能提升，循环1800圈后的容量保持率达到87％以上。
实施例9～21
通过与实施例4中基本上相同的方法制备隔膜和二次电池，不同之处在于，组分B中还加入长径比为约800的一维导电材料单臂碳纳米管，并且在制备的纳米纤维中，相对于纳米纤维层的总重量，补锂剂、聚合物、零维导电材料和一维导电材料的含量如表3所示。
通过上文所述的测试方法，分别测量实施例9～21的隔膜的纳米纤维层的孔隙率，以及用实施例9～21的隔膜制备的电池的首次库伦效率和容量保持率，结果一并示于表3中。
表3
Figure PCTCN2022075173-appb-000003
从以上结果可以看出，与实施例4-8相比，在实施例9-21中，由于纳米纤维中还添加了能够部分暴露于纳米纤维外部的一维导电材料，因此，不仅可以进一步促进电子在纳米 纤维层内的迁移，而且其部分暴露的部分还可以额外地促进纳米纤维层和正极活性材料之间的电子迁移，从而进一步提高补锂剂的利用效率。结果，在实施例9-21中，电池的初始放电容量提高，电池的首次库伦效率保持在90％以上，并且，电池的循环性能大大提升，循环1800圈后的容量保持率达到89％以上。
在实施例13和14中，相对于100重量份聚合物，补锂剂的含量分别为77重量份和62.5重量份，在优选的60-80重量份的优选范围内。结果，与其中补锂剂含量为50重量份的实施例12相比，电池在循环1800圈后的容量保持率有所提升。
实施例22～25
通过与实施例4中基本上相同的方法制备隔膜和二次电池，不同之处在于，组分B中加入的零维导电材料炭黑的粒径如表4所示。
通过上文所述的测试方法，分别测量实施例22～25的隔膜的纳米纤维层的孔隙率，以及用实施例22～25的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表4中。为方便比较，实施例4的隔膜的纳米纤维层的孔隙率以及用实施例4的隔膜制备的电池的首次库伦效率和容量保持率也一并列于表4中。
表4
  零维导电材料粒径(nm) 孔隙率 首次库伦效率 容量保持率
实施例22 25 82％ 91％ 84％
实施例23 30 82％ 92％ 88％
实施例4 40 82％ 92％ 87％
实施例24 50 82％ 92％ 86％
实施例25 55 79％ 91％ 85％
从以上结果可以看出，与实施例22和实施例25相比，在实施例4、23和24中，零维导电材料的粒径处于30～50nm的优选范围内，因此，在相同的添加量下可以实现更多的点对点电子通路，同时不会对静电纺丝工艺产生不利影响，从而保证补锂剂的利用效率得到进一步提升。结果，在实施例4、23和24中，电池的初始放电容量提升，电池的首次库伦效率高达92％，并且，电池的循环性能提升，循环1800圈后的容量保持率达到86％以上。
实施例26～30
通过与实施例4中基本上相同的方法制备隔膜和二次电池，不同之处在于，组分B中加入长径比如表5所示的一维导电材料单臂碳纳米管。另外，在制备的纳米纤维中，相对于纳米纤维层的总重量，补锂剂、聚合物、零维导电材料和一维导电材料的含量分别为39.8％、59％、1％和0.2％。
通过上文所述的测试方法，分别测量实施例26～30的隔膜的纳米纤维层的孔隙率，以及用实施例26～30的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表5中。
表5
  长径比 孔隙率 首次库伦效率 容量保持率
实施例26 450 82％ 93％ 90％
实施例27 500 81％ 94％ 91％
实施例28 750 81％ 92％ 91％
实施例29 1000 81％ 94％ 91％
实施例30 1050 79％ 93％ 90％
从以上结果可以看出，与实施例26和实施例30相比，在实施例27～29中，一维导电材料的长径比处于500～1000nm的优选范围内，因此，一维导电材料能够充分发挥其促进纳米纤维层和正极活性材料之间的电子迁移的额外作用，从而保证补锂剂的利用效率得到进一步提升。结果，在实施例27～29中，电池的初始放电容量提升，电池的首次库伦效率保持在92％以上，并且，电池的循环性能提升，循环1800圈后的容量保持率达到91％以上。
实施例31～34
通过与实施例4基本上相同的方法制备隔膜和二次电池，不同之处在于，补锂剂的粒径如表6所示。
通过上文所述的测试方法，分别测量实施例31～34的隔膜的纳米纤维层的孔隙率，以及用实施例31～34的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表6中。为方便比较，实施例4的隔膜的纳米纤维层的孔隙率以及用实施例4的隔膜制备的电池的首次库伦效率和容量保持率也一并列于表6中。
表6
  补锂剂粒径(nm) 孔隙率 首次库伦效率 容量保持率
实施例31 50 82％ 89％ 83％
实施例32 80 82％ 90％ 85％
实施例4 100 82％ 90％ 85％
实施例33 150 82％ 90％ 85％
实施例34 200 79％ 90％ 82％
从以上结果可以看出，在实施例4和31～34中，补锂剂的粒径处于50～200nm的优选范围内，起到了优化纳米纤维直径的作用，以使纳米纤维层具有更优的结构，从而有效避免对基材层空隙的堵塞，提升隔膜对电解液的浸润性和保液性，更好地促进纳米纤维层内补锂剂持续的锂离子迁移。结果，在实施例4和31～34中，电池的初始放电容量提升，电池的首次库伦效率高达89％以上，并且，电池的循环性能提升，循环1800圈后的容量保持率达到82％以上。
在实施例4、32和33中，补锂剂的粒径处于80～150nm的进一步优选的范围内，电池的初始放电容量进一步提升，电池的首次库伦效率高达90％，并且，电池的循环性能进一步提升，循环1800圈后的容量保持率高达85％。
实施例35～39
通过与实施例9基本上相同的方法制备隔膜和二次电池，不同之处在于，在静电纺丝工序中，调节纺丝头的内径，使得纳米纤维的直径如表7所示。另外，在制备的纳米纤维中，相对于纳米纤维层的总重量，补锂剂、聚合物、零维导电材料和一维导电材料的含量分别为39.8％、59.0％、1.0％和0.2％。
通过上文所述的测试方法，分别测量实施例35～39的隔膜的纳米纤维层的孔隙率，以及用实施例35～39的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表7中。
表7
  纳米纤维直径(nm) 孔隙率 首次库伦效率 容量保持率
实施例35 100 81％ 92％ 91％
实施例36 200 82％ 92％ 92％
实施例37 250 82％ 95％ 92％
实施例38 300 80％ 92％ 91％
实施例39 500 75％ 91％ 89％
从以上结果可以看出，在实施例35-39中，纳米纤维层的直径处于100～500nm的优选范围内，使纳米纤维层具有更优的结构，从而更有效地避免对基材层空隙的堵塞，提升隔膜对电解液的浸润性和保液性，更好地促进纳米纤维层内补锂剂持续的锂离子迁移。结果，在实施例35-39中，电池的初始放电容量大大提升，电池的首次库伦效率高达91％以上，并且，电池的循环性能提升，循环1800圈后的容量保持率保持在89％以上。
在实施例36和实施例37中，纳米纤维的直径处于200～250nm的进一步优选的范围内，电池的初始放电容量进一步提升，电池的首次库伦效率高达94％以上，并且，电池的循环性能进一步提升，循环1800圈后的容量保持率保持在92％以上。
实施例40～43
通过与实施例14中基本上相同的方法制备隔膜和二次电池，不同之处在于，在静电纺丝工序中，调节静电纺丝时间，使得形成的纳米纤维层的厚度如表8所示。
通过上文所述的测试方法，分别测量实施例40～43的隔膜的纳米纤维层的孔隙率，以及用实施例40～43的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表8中。为方便比较，实施例14的隔膜的纳米纤维层的孔隙率以及用实施例14的隔膜制备的电池的首次库伦效率和容量保持率也一并列于表8中。
表8
  纳米纤维层厚度(μm) 孔隙率 首次库伦效率 容量保持率
实施例40 1.0 82％ 94％ 91％
实施例14 1.5 82％ 96％ 92％
实施例41 2.5 82％ 97％ 93％
实施例42 3.0 82％ 98％ 89％
实施例43 5.0 82％ 98％ 89％
从以上结果可以看出，在实施例14和40～43中，纳米纤维层的厚度处于1.0～5.0μm的优选范围内，有利于纳米纤维层中包括足够量的补锂剂，起到充分的补锂作用，同时不会占据过多的空间，对隔膜性能产生不利影响。结果，在实施例14和40～43中，电池的初始放电容量大大提升，电池的首次库伦效率高达94％以上，并且，电池的循环性能大大 提升，循环1800圈后的容量保持率保持在89％以上。
在实施例14和实施例41中，纳米纤维层的厚度处于1.5～2.5μm的进一步优选的范围内，电池的初始放电容量进一步提升，电池的首次库伦效率高达96％以上，并且，电池的循环性能进一步提升，循环1800圈后的容量保持率高达92％以上。
实施例44～46
通过与实施例9中基本上相同的方法制备隔膜和二次电池，不同之处在于，在组分A的制备中，形成的聚合物溶液具有如表9所示的固含量。
通过上文所述的测试方法，分别测量实施例44～46的隔膜的纳米纤维层的孔隙率，以及用实施例44～46的隔膜制备的电池的首次库伦效率和容量保持率，结果示于表9中。为方便比较，实施例9的隔膜的纳米纤维层的孔隙率以及用实施例9的隔膜制备的电池的首次库伦效率和容量保持率也一并列于表9中。
表9
  固含量 孔隙率 首次库伦效率 容量保持率
实施例9 20％ 82％ 92％ 92％
实施例44 25％ 82％ 92％ 92％
实施例45 30％ 82％ 91％ 91％
实施例46 40％ 79％ 91％ 90％
从以上结果可以看出，在实施例9和44～46中，在静电纺丝用分散液的制备中，聚合物溶液的固含量处于20～40％的优选范围内。因此，在将其加入到补锂剂或者补锂剂与导电材料的共混物中并高速分散后，得到的分散液非常适合于静电纺丝工序，从而保证静电纺丝产生的纳米纤维的直径更均匀，补锂剂和/或导电材料的分布以及纳米纤维层的孔隙分布更均匀，保证补锂剂的补锂作用以及隔膜的性能均得以稳定化。结果，在实施例9和44～46中，电池的初始放电容量优异，电池的首次库伦效率高达91％以上，并且，电池的循环性能进一步提升，循环1800圈后的容量保持率高达90％以上。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也 包含在本申请的范围内。
工业应用性
本申请的隔膜具有包括补锂剂、聚合物和任选的导电材料的纳米纤维层作为补锂剂层，大大提高了补锂剂的利用效率，在应用于二次电池时大大提高了电池的初始放电容量，提升了电池的循环性能，延长了电池寿命。因而，本申请适于工业应用。

Claims (19)

  1. 一种二次电池用隔膜，其包括：
    基材层；和
    设置在所述基材层的一个表面上的纳米纤维层，
    所述纳米纤维层包括补锂剂、聚合物、和任选的导电材料，其中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5.0重量％。
  2. 根据权利要求1所述的隔膜，其中，所述导电材料包括零维导电材料和任选的一维导电材料，并且相对于所述纳米纤维层的总重量，所述零维导电材料的含量为1.0～5.0重量％，所述一维导电材料的含量为0～0.3重量％。
  3. 根据权利要求2所述的隔膜，其中，所述零维导电材料具有30～50 nm的粒径；可选地，所述零维导电材料是选自炭黑、乙炔黑和科琴黑中的一种或多种。
  4. 根据权利要求2或3所述的隔膜，其中，所述一维导电材料具有500～1000的长径比；可选地，所述一维导电材料是碳纳米管，可选为单臂纳米管、多臂纳米管或者二者的组合。
  5. 根据权利要求1～4中任一项所述的隔膜，其中所述补锂剂是选自Li 2C 2O 4、C 4BLiO 8、Li 15Si 4、Li 4Sn、Li 2NiO 2、LiF、Li 2TiO 3、Li 2CrO 4、Li 2Cr 2O 7、Li 4SiO 4、Li 2SiO 3、Li 3AsO 4、Li 2SeO 4、Li 2SeO 3、LiVO 3、LiAlO 2、Li 3PO 4、Li 2B 8O 13、Li 2B 4O 7、LiBO 2、Li 3AlF 6、Li 2SnF 6、和LiAsF 6中的一种或多种，可选为Li 2NiO 2、Li 4Sn和LiAsF 6中的一种或多种。
  6. 根据权利要求1～5中任一项所述的隔膜，其中所述补锂剂的粒径为50～200nm，可选为80～150nm。
  7. 根据权利要求1～6中任一项所述的隔膜，其中，相对于100重量份所述聚合物，所述补锂剂的量为40～100重量份，可选为60～80重量份。
  8. 根据权利要求2～7中任一项所述的隔膜，其中，相对于100重量份所述补锂剂，所述零维导电材料的量为1～12.5重量份；并且所述一维导电材料的量为0.15～0.75重量份。
  9. 根据权利要求1～8中任一项所述的隔膜，其中，所述聚合物是选自聚偏氯乙烯、聚酰亚胺、聚丙烯腈和聚苯乙烯中的一种或多种。
  10. 根据权利要求1～9中任一项所述的隔膜，其中，所述纳米纤维层中的纳米纤维的直径为100～500nm，可选为200～250nm。
  11. 根据权利要求1～10中任一项所述的隔膜，其中，所述纳米纤维层的厚度为1.0～5.0μm，可选为1.5～2.5μm。
  12. 根据权利要求1～11中任一项所述的隔膜，其中，所述纳米纤维层的孔隙率为80％以上。
  13. 一种二次电池用隔膜的制备方法，包括：
    将聚合物溶解在溶剂中，得到聚合物溶液；
    将所述聚合物溶液加入到补锂剂或者补锂剂与导电材料的共混物中，并进行高速分散，得到分散液；
    将所述分散液通过静电纺丝附着于基材层的一个表面上，形成纳米纤维层，
    其中，在所述纳米纤维层中，相对于所述纳米纤维层的总重量，所述补锂剂的含量为30.0～50.0重量％，所述聚合物的含量为50.0～70.0重量％，所述导电材料的含量为0～5重量％。
  14. 根据权利要求13所述的方法，其中所述聚合物溶液的固含量为20～40重量％，可选为20～25重量％。
  15. 根据权利要求13或14所述的方法，其中所述纳米纤维层的厚度为1.0～5.0μm，可选为1.5～2.5μm。
  16. 一种二次电池，其包括：
    正极；
    负极；
    电解质；和
    权利要求1～12中任一项所述的隔膜，其中
    所述纳米纤维层设置在所述基材层的面向所述正极的表面上。
  17. 一种电池模块，其包括权利要求16所述的二次电池。
  18. 一种电池包，其包括权利要求17所述的电池模块。
  19. 一种用电装置，其包括权利要求16所述的二次电池、权利要求17所述的电池模块和权利要求18所述的电池包中的至少一种。
PCT/CN2022/075173 2022-01-30 2022-01-30 二次电池用隔膜及其制备方法、二次电池、电池模块、电池包和用电装置 WO2023142106A1 (zh)

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