WO2023010927A1 - 二次电池、电池模块、电池包及用电装置 - Google Patents

二次电池、电池模块、电池包及用电装置 Download PDF

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WO2023010927A1
WO2023010927A1 PCT/CN2022/091749 CN2022091749W WO2023010927A1 WO 2023010927 A1 WO2023010927 A1 WO 2023010927A1 CN 2022091749 W CN2022091749 W CN 2022091749W WO 2023010927 A1 WO2023010927 A1 WO 2023010927A1
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secondary battery
negative electrode
battery
formation
general formula
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PCT/CN2022/091749
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English (en)
French (fr)
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李丽叶
陈培培
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宁德时代新能源科技股份有限公司
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Publication of WO2023010927A1 publication Critical patent/WO2023010927A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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 a secondary battery, in particular to a secondary battery with high energy density, a battery module using the secondary battery, a battery pack and an electrical device.
  • the present application is made in view of the above technical problems, and its purpose is to provide a secondary battery capable of taking into account high energy density, safety performance and excellent internal resistance of the battery cell.
  • the first aspect of the present application provides a secondary battery, comprising: an electrode assembly, which includes a negative electrode sheet; and an electrolyte, which contains a compound represented by the following general formula (I),
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector,
  • A is a single bond or an alkyl group with 1 to 5 carbon atoms
  • R is R2 is Wherein R3 is an alkyl or alkoxy group with 1 to 3 carbon atoms,
  • the mass percentage w (%) of the compound represented by the general formula (I) in the electrolyte, the value of the formation and gas generation area coefficient ⁇ of the negative electrode sheet and the formation and gas generation and exhaust rate factor ⁇ of the electrode assembly satisfy the following formula (1),
  • M is the load per unit area (mg/cm 2 ) of the negative electrode active material on at least one surface of the negative electrode current collector, and the range of M is 5 to 100 (mg/cm 2 );
  • S is the negative electrode electrode The specific surface area of the sheet (m 2 /g), S ranges from 0.1 to 10 (m 2 /g),
  • Q is the rated capacity (Ah) of the secondary battery
  • V is the volume (L) of the electrode assembly
  • ⁇ satisfies: 0.05 ⁇ 0.15.
  • the present application contains specific compounds in the electrolyte, and the content w of the compound in the electrolyte, the formation and gas generation area coefficient ⁇ of the negative electrode sheet, and the formation and gas emission rate factor ⁇ of the electrode assembly
  • the numerical value is controlled within a certain relationship range, so as to reduce the amount of formed gas and accelerate its discharge, maintain an excellent formed interface, ensure the safety performance of the battery, and increase the volumetric energy density of the battery and reduce the internal resistance of the battery cell.
  • the compound represented by the general formula (I) is selected from at least one of the following compounds 1-16.
  • the mass ratio w (%) of the compound represented by the general formula (I) in the electrolyte is controlled, and the area coefficient ⁇ of the chemical conversion gas production and the exhaust rate factor ⁇ satisfy the relationship: 5 ⁇ 0.1 ⁇ w ⁇ / ⁇ 128, which can better reduce the amount of gas produced by formation to make the formation interface excellent, while taking into account the high energy density and low inner core resistance of the battery.
  • the range of the mass percentage w (%) of the compound represented by the general formula (I) in the electrolyte is 0.05 to 10, optionally 0.2 to 5, so as to reduce the weight of the electrolyte. Restore and decompose gas production, and take into account the reduction of internal resistance of the battery cell.
  • the loading per unit area M (unit: mg/cm 2 ) of the negative active material on at least one surface of the negative current collector is adjusted to be 10- 50, so that the amount of gas produced by chemical conversion can be controlled, and the volumetric energy density of the battery cell can be improved at the same time.
  • the volume energy density of the cell can be increased while further controlling the amount of the converted gas.
  • the range of the exhaust rate factor ⁇ (L/Ah) of the electrode assembly is controlled to 0.06 ⁇ ⁇ ⁇ 0.1, so that the discharge of the converted gas and the volumetric energy density of the battery can be taken into account, and the Without reducing the volumetric energy density of the battery, increase the reserved space for gas production as much as possible, so as to accelerate the discharge of gas production and maintain the interface after formation.
  • the porosity of the negative electrode active material is 10% to 40%, which can quickly diffuse the gas generated inside the negative electrode active material layer, and at the same time, the electrode assembly can also have a higher volumetric energy density and a higher Low cell internal resistance.
  • the electrolytic solution further contains fluoroethylene carbonate and/or 1,3-propane sultone.
  • fluoroethylene carbonate and/or 1,3-propane sultone Under the premise of ensuring the high energy density and low gas production of the secondary battery, the high and low temperature cycle performance of the secondary battery can be significantly improved.
  • the second aspect of the present application further provides a battery module including the secondary battery according to the first aspect of the present application.
  • the third aspect of the present application further provides a battery pack, which includes the secondary battery of the first aspect of the present application or the battery module of the second aspect.
  • a fourth aspect of the present application further provides an electrical device, which includes the secondary battery of the first aspect of the present application, the battery module of the second aspect, or the battery pack of the third aspect.
  • the battery module, battery pack and electric device of the present application include the secondary battery according to the first aspect of the present application, and thus have at least the same or similar technical effects as the above secondary battery.
  • FIG. 1 is a schematic diagram of a secondary battery according to one embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG. 1 .
  • Fig. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Fig. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Fig. 5 is an exploded view of the battery pack according to one embodiment of the present application shown in Fig. 4 .
  • Fig. 6 is a schematic diagram of an electrical device 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 contemplated. Additionally, 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
  • a secondary battery is provided.
  • the secondary battery of the present application includes: an electrode assembly; and an electrolyte for wetting the electrode assembly, wherein the electrode assembly contains a negative electrode sheet, and the negative electrode sheet includes a negative electrode collector and a negative electrode arranged on at least one surface of the negative electrode collector active material layer.
  • the secondary battery also includes a positive pole piece, and a separator arranged between the positive pole piece and the negative pole piece.
  • An electrolytic solution containing a compound represented by the following general formula (I) is used in the secondary battery of the present application.
  • A is a single bond or an alkyl group with 1 to 5 carbon atoms
  • R is R2 is
  • R 3 is an alkyl or alkoxy group having 1 to 3 carbon atoms.
  • the mass percentage w (%) of the compound represented by the general formula (I) in the electrolyte, the value of the formation and gas generation area coefficient ⁇ of the negative electrode sheet and the formation and gas generation and exhaust rate factor ⁇ of the electrode assembly satisfy the following formula (1),
  • M is the load per unit area of the negative electrode active material on at least one surface of the negative electrode current collector, and the range of M is 5 to 100 (mg/cm 2 ); S is the specific surface area of the negative electrode sheet (m 2 /g), S ranges from 0.1 to 10 (m 2 /g),
  • Q is the rated capacity (Ah) of the secondary battery
  • V is the volume (L) of the electrode assembly
  • the present application includes the compound represented by the above-mentioned general formula (I) in the secondary battery, and the content w of the compound in the electrolyte, the formation of the gas production area coefficient ⁇ of the negative electrode sheet and the electrode assembly
  • the numerical value of the rate factor ⁇ of gas formation and exhaust is controlled within a certain relationship range, so that the amount of gas produced by formation can be reduced, the discharge of gas produced by formation can be accelerated, the excellent formation interface can be maintained, the safety performance of the battery can be guaranteed, and the volume of the battery can be increased
  • the energy density is increased, and the internal resistance of the cell is reduced, so that the electrical performance of the secondary battery is excellent.
  • the gas will be enriched at the interface between the negative electrode and the separator, forming bubbles, blocking the transmission of lithium ions, and eventually forming black spots and local lithium precipitation on the surface of the negative electrode, resulting in poor interface of the negative electrode and capacity loss. Abnormal, and battery safety issues.
  • the volume V of the electrode assembly is mainly composed of three parts: the volume of the structural parts, the volume of the active material and the reserved volume for gas production.
  • the volume of the active material generally directly determines the rated capacity Q of the secondary battery.
  • V/Q the ratio of the volume of the electrode assembly to the rated capacity of the battery
  • another method to reduce the enrichment of the formation gas at the interface between the negative electrode and the separator is to reduce the gas production of the formation gas.
  • the compound represented by the above general formula (I) has a higher reduction potential than conventional solvents, and can be preferentially reduced on the surface of the negative electrode during formation, thereby inhibiting the reduction and decomposition of the electrolyte solvent on the surface of the negative electrode. Thereby reducing the amount of gas produced by the reductive decomposition of the electrolyte solvent.
  • the compound represented by the general formula (I) is reduced on the surface of the negative electrode to form a sulfur-containing organic coating layer without generating gas products, so there is no reduction and decomposition of additives to generate gas.
  • the compound represented by the general formula (I) is an efficient electrolyte additive for inhibiting the formation of gas in the battery cell, and the compound represented by the general formula (I) can be significantly controlled by adding the compound represented by the general formula (I) as an additive in the electrolyte of the secondary battery.
  • the amount of gas produced by chemical conversion is maintained to maintain a good state of the contact interface between the electrolyte and the negative electrode active material. Therefore, applying the electrolyte solution containing the compound represented by the general formula (I) to a high energy density cell can achieve both high energy density and excellent formation interface to a certain extent.
  • M is the loading amount per unit area of the negative active material on at least one surface of the negative current collector (unit: mg/cm 2 );
  • S is the specific surface area of the negative electrode sheet (unit: m 2 /g).
  • V is the volume of the electrode assembly (unit: L)
  • Q is the capacity of the electrode assembly (unit: Ah).
  • the mass ratio w of the compound represented by the general formula (I) in the electrolyte, the formation gas production area coefficient ⁇ , and the exhaust path coefficient ⁇ satisfy the relationship: 5 ⁇ 0.1 ⁇ w ⁇ / ⁇ 128.
  • the range of 0.1 ⁇ w ⁇ / ⁇ is within the above range, the formation gas production can be reduced so that the formation interface is excellent, and the high energy density and low inner core resistance of the battery can be better taken into account.
  • the range of the rate factor ⁇ of formation gas generation and exhaust is controlled to be 0.05 ⁇ 0.15.
  • the smaller ⁇ the smaller the reserved space for gas production, and the higher the volumetric energy density of the electrode assembly; however, too small ⁇ will lead to too small reserved space, which is not conducive to the discharge of the formed gas from the interface during the storage process. Deteriorating the interface and accelerating capacity fading.
  • ⁇ ranges from 0.06 ⁇ 0.1.
  • ⁇ ranges from 0.06 ⁇ 0.1.
  • the theoretical relational formula proposed in this application is not limited to be applicable to one battery structure.
  • the outer package of the battery, the shape of the battery, or the assembly method of the electrical components (such as lamination, winding, etc.) are changed due to other requirements, the Theoretical relations still apply.
  • 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 secondary battery may include an outer package.
  • the outer package 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. 1 shows a square-shaped secondary battery 5 as an example.
  • the outer package may include a housing 51 and a top cover assembly 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 casing 51 has an opening communicating with the accommodating cavity, and the top cover assembly 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 cavity. 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 electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece, and contains electrolyte salt, organic solvent and organic additives.
  • electrolyte salt organic solvent and organic additives.
  • electrolytes can be liquid, gel or all solid.
  • the electrolyte is an electrolytic solution.
  • the electrolyte contains a compound represented by the following general formula (I),
  • A is a single bond or an alkyl group with 1 to 5 carbon atoms
  • R is R2 is Wherein R 3 is an alkyl or alkoxy group with 1 to 3 carbon atoms.
  • the compound represented by the above general formula (I) not only can be preferentially reduced on the surface of the negative electrode than the electrolyte solvent, reducing the reduction and decomposition of the solvent to generate gas, but also there will be no gas products in its own reduction.
  • the compound represented by the general formula (I) is selected from at least one of the following compounds 1-16.
  • the weight ratio w (unit: %) of the compound represented by the general formula (I) in the electrolyte ranges from 0.05 to 10, and may be 0.2 to 5.
  • the content range of the compound represented by the general formula (I) within the above range, it can play a certain role in inhibiting the formation of gas, thereby obtaining a good chemical conversion interface.
  • the amount of the compounds shown is used to maintain the low internal resistance of the secondary battery at room temperature.
  • the organic solvent contained in the electrolyte solution of the present application can be selected according to actual needs, specifically, it can include one or more of chain carbonates, cyclic carbonates, and carboxylates.
  • chain carbonates, cyclic carbonates, and carboxylates are not specifically limited, and can be selected according to actual needs.
  • the organic solvent in the electrolyte may include diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethylene propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, One or more of ⁇ -butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl propionate, tetrahydrofuran.
  • the electrolytic solution of the present application may further contain as other additives selected from cyclic carbonate compounds containing unsaturated bonds, halogen-substituted cyclic carbonate compounds, sulfite compounds, sulfonic acid internal At least one of ester compound, disulfonic acid compound, nitrile compound, aromatic compound, isocyanate compound, phosphazene compound, cyclic acid anhydride compound, phosphite compound, phosphate compound, borate compound, carboxylate compound.
  • the performance of the battery cell can be optimized and the high and low temperature cycle performance of the secondary battery can be improved.
  • fluoroethylene carbonate (FEC), 1,3-propane sultone (PS) etc. are included in the electrolyte, when additional fluoroethylene carbonate (FEC) and / or 1,3-propane sultone (PS), under the premise of ensuring the secondary battery has high energy density and low gas production, it can further reduce the internal resistance of the battery cell, and significantly improve the high performance of the secondary battery Low temperature cycle performance.
  • the type of the electrolyte salt of the present application is not particularly limited, and can be selected according to actual needs.
  • the electrolyte salt can be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate , lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector and including the negative electrode active material, and the negative electrode film layer includes the 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 negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material can be selected from at least one of simple tin, tin oxide and tin alloy. But the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the range of the load per unit area M (unit: mg/cm 2 ) of the negative electrode active material is controlled to be 5-100, and the specific surface area S (unit: m 2 /g) ranges from 0.1 to 10. If the loading M per unit area of the negative electrode active material is too low, the energy density of the battery will be reduced; if it is too high, the lithium ion transmission rate inside the material will be reduced, affecting the kinetic performance. In addition, if the specific surface area S of the negative electrode sheet is too small, the electrochemical reaction area will be reduced, and the loading capacity needs to be further reduced to maintain the charging capacity, and if it is too large, the amount of formed gas will be large and the interface will deteriorate.
  • M can be selected to be 10-50 (mg/cm 2 ), which can control the amount of gas produced by chemical formation, ensure a good full-charge interface after chemical formation, and then increase the volumetric energy density of the battery cell and reduce the energy density of the battery cell. internal resistance.
  • optional S is 0.5-5 (m 2 /g). It is possible to further control the amount of gas produced by chemical formation to ensure a good full-charge interface after chemical formation, thereby improving the volumetric energy density of the battery cell while reducing the internal resistance of the battery cell.
  • the porosity of the negative electrode active material layer is 10% to 40%, and the larger the porosity of the negative electrode active material layer is, the easier it is for the formed gas to diffuse from the inside of the negative electrode active material layer to the interface between the negative electrode and the separator. The more the smoother, the less prone to black spots at the interface, but on the other hand, it will lead to a decrease in the volumetric energy density of the electrode assembly; the smaller the porosity of the negative electrode active material layer, the formed gas diffuses from the inside of the negative electrode active material layer to the negative electrode and the separator The less the path of the interface, the slower the gas discharge rate, and the more prone to interface black spots.
  • the gas generated inside the negative electrode active material layer can be quickly diffused out, ensuring a good filling interface after formation, and the electrode assembly can also have a higher volume Energy density and lower cell internal resistance.
  • the negative electrode active material layer in the present application can also include a conductive agent, a binder and other optional additives, wherein the type and content of the conductive agent and the binder are not specifically limited, and can be determined according to Choose according to actual needs.
  • the negative electrode active material layer is usually formed by coating and drying the negative electrode slurry.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material and optional conductive agent and binder in a solvent and stirring evenly.
  • the solvent can be N-methylpyrrolidone (NMP) or deionized water.
  • 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
  • Other optional additives are, for example, thickeners (such as sodium carboxymethylcellulose (CMC-Na) and the like.
  • the type of the negative electrode collector is not specifically limited, and can be selected according to actual needs.
  • the negative electrode current collector can be metal foil or composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate.
  • 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, polyethylene terephthalate ester, polybutylene terephthalate, polystyrene, polyethylene, etc.)
  • the positive pole piece includes a positive current collector and a positive active material arranged on at least one surface of the positive current collector.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode material is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • a metal foil or a composite current collector can be used as the positive electrode current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector 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 Ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and other substrates), but the present application is not limited to these Material.
  • PP polypropylene
  • PET polyethylene terephthalic acid Ethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may further optionally include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of meta-copolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer may also optionally include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • 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. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 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 above 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 electric device, which includes more than one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack provided in the present application can be used as a power source of a device, and can also be used as an energy storage unit of a device.
  • the electrical device of the present application can be, but not limited to, mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, Electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • secondary batteries, battery modules, or battery packs can be selected according to their usage requirements.
  • Figure 6 is an example device.
  • the device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • battery packs or battery modules can be employed.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • the secondary batteries of Examples 1-24 and Comparative Examples 1-9 were prepared according to the following methods.
  • the positive electrode active material LiNi 0.8 Mn 0.1 Co 0.1 O 2 , the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were added to the solvent N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3, After mixing evenly, the positive electrode slurry is obtained, and the positive electrode slurry is coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained through drying, cold pressing, slitting and other processes.
  • Negative active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickener carboxymethylcellulose sodium (CMC-Na) are added to the solvent according to the weight ratio of 95:2:2:1.
  • Negative electrode slurry was obtained after mixing evenly in ionized water, and the negative electrode slurry was coated on the copper foil of the negative electrode collector, and the negative electrode sheet was obtained through drying, cold pressing, slitting and other processes, wherein the parameters of the negative electrode sheet are shown in the table 1.
  • a polypropylene film was used as the separator.
  • the negative electrode active material on the negative electrode sheet of all examples and comparative examples was scraped off with a blade, and then tested with reference to standard GB/T 21650.2-2008. Refer to Table 1 for specific values.
  • the above-mentioned negative pole piece is a pole piece with a negative electrode current collector provided with a negative electrode active material, and the porosity of the negative pole piece is also the porosity of the negative electrode active material layer. Refer to Table 3 for the specific value of the porosity of the negative electrode sheet.
  • Comparative Examples 7 to 9 that did not add the compound represented by the general formula (I)
  • Comparative Example 7 because the loading capacity of the negative electrode active material was small, although the compound represented by the general formula (I) was not added to the solvent,
  • the compound represented by the general formula (I) was not added to the solvent
  • the specific surface area of the negative electrode sheet, the loading capacity, the shell volume of the electrode assembly and the rated capacity of the battery cell are all the same, but because no additives are added to the solvent, it is similar to that of Example 4.
  • VC vinyl carbonate
  • Comparative Example 9 VC (vinylene carbonate) used in the related art was used as an additive, which can suppress the reduction of the electrolyte solvent to reduce chemical conversion gas generation.
  • VC itself will be reduced and decomposed to generate gas products, resulting in insignificant improvement and seriously deteriorating the internal resistance of the cell.
  • Table 3 shows Examples 20 to 24 that have the same specific surface area S of the negative electrode sheet, load M, and case volume of the electrode assembly as in Example 3 but changed the porosity of the negative electrode material layer used.
  • Table 3 shows Examples 20 to 24 that have the same specific surface area S of the negative electrode sheet, load M, and case volume of the electrode assembly as in Example 3 but changed the porosity of the negative electrode material layer used.
  • the increase of the porosity of the negative electrode active material layer the smoother the path of the formation gas diffusing from the inside of the negative electrode active material layer to the interface between the negative electrode and the separator is, the less likely it is to have interface black.
  • the increase in the porosity of the negative electrode active material layer will lead to a decrease in the volumetric energy density of the electrode assembly.
  • Table 4 Relevant parameters and performance test table of secondary batteries of some embodiments and comparative examples
  • the electrolyte solution of the compound represented by the general formula (I) is added with a suitable content and 0.1 ⁇ w ⁇ / ⁇ is adjusted within the range of 1.2 ⁇ 255, Not only can it take into account the high volume energy density and low internal resistance of the cell, reduce the formation gas and improve the formation interface, but also improve the cycle performance of the cell at room temperature and high temperature, mainly because the formation interface has been significantly improved, making the negative electrode interface more stable.
  • FEC and PS are further added to form a film on the negative electrode, which can further improve the stability of the negative electrode interface, thereby further improving the normal temperature and high temperature cycle performance.

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Abstract

一种二次电池、电池模块、电池包及用电装置，其中，二次电池包括：包含负极极片的电极组件，以及含有通式(Ⅰ)所示的化合物的电解液。二次电池中，通过控制负极极片的化成产气面积系数α、化成产气排气速率因子β、以及通式(Ⅰ)所示的化合物在电解液中的质量百分含量w的数值满足下式(1)的关系：1.2≤0.1×w×α/β≤255 式(1) 。

Description

二次电池、电池模块、电池包及用电装置
相关申请的交叉引用
本申请要求享有于2021年07月31日提交的名称为“二次电池、电池模块、电池包及用电装置”的中国专利申请202110877250.3的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及一种二次电池，尤其涉及一种高能量密度的二次电池、使用了该二次电池的电池模块、电池包和用电装置。
背景技术
随着新能源领域的快速发展，二次电池凭借其优良的电化学性能、无记忆效应、环境污染小等优势广泛应用于各类大型动力装置、储能系统以及各类消费类产品中，尤其广泛应用于纯电动汽车、混合电动汽车等新能源汽车领域。
在新能源汽车领域，消费者对二次电池的续航能力提出了更高的要求。目前的二次电池难以满足人们对续航能力的更高需求，因此更高能量密度的二次电池的开发成为二次电池研发的主要方向之一。另外，由于二次电池在使用过程中会产生化成气体，二次电池的能量密度越高，化成产气量越多，会影响到电池的电性能和安全性能。因此，亟待开发出能够兼顾高能量密度且安全性能优良的二次电池。
发明内容
本申请是鉴于上述技术问题而进行的，其目的在于，提供一种二次电池，能够兼顾二次电池的高能量密度、安全性能以及优异的电芯内阻。
为了达到上述目的，本申请第一方面提供了一种二次电池，包括：电极组件，其包含负极极片；以及电解液，其含有下述通式(Ⅰ)所示的化合物，
负极极片包含负极集流体和设置于负极集流体的至少一个表面的负极活性材料，
Figure PCTCN2022091749-appb-000001
通式(Ⅰ)中，A为单键或碳原子数为1～5的烷基，R 1为
Figure PCTCN2022091749-appb-000002
Figure PCTCN2022091749-appb-000003
R 2为
Figure PCTCN2022091749-appb-000004
其中R 3为碳原子数1～3的烷基或烷氧基，
通式(Ⅰ)所示的化合物在电解液中的质量百分含量w(％)、负极极片的化成产气面积系数α和电极组件的化成产气排气速率因子β的数值满足下式(1)，
1.2≤0.1×w×α/β≤255     式(1)
其中，α＝M×S         式(2)
式(2)中，M为负极活性材料在负极集流体的至少一个表面上的单位面积负载量(mg/cm 2)，M的范围为5～100(mg/cm 2)；S为负极极片的比表面积(m 2/g)，S的范围为0.1～10(m 2/g)，
β＝10×V/Q          式(3)
式(3)中，Q为二次电池的额定容量(Ah)，V为电极组件的体积(L)，β的数值满足：0.05≤β≤0.15。
由此，本申请通过在电解液中包含特定的化合物，并将该化合物在电解液中的含量w、负极极片的化成产气面积系数α以及电极组件的化成产气排气速率因子β的数值控制在一定的关系范围内，从而能够减少化成产气量且加速其排出，保持优良的化成界面，保证电池的安全性能，而且能够增大电池的体积能量密度，降低电芯内阻。
另外，在任意实施方式中，该通式(Ⅰ)所示的化合物选自如下化合物1-16中的至少一种。
Figure PCTCN2022091749-appb-000005
Figure PCTCN2022091749-appb-000006
能够进一步减少化成产气量以使化成界面优良和兼顾电芯的高能量密度及内阻性能。
另外，在任意实施方式中，控制通式(Ⅰ)所示的化合物在电解液中的质量占比w(％)与化成产气面积系数α以及排气速率因子β满足关系式：5≤0.1×w×α/β≤128，从而能够更好地减少化成产气量以使化成界面优良，同时兼顾电芯的高能量密度及低的内芯电阻。
另外，在任意实施方式中，通式(Ⅰ)所示的化合物在电解液中的质量百分含量w(％)的范围为0.05～10，可选为0.2～5，从而能够降低电解液的还原分解产气量，并兼顾降低电芯内阻。
在任意实施方式中，通过控制负极极片中的负极活性材料的负载量，调节负极活性材料在负极集流体的至少一个表面上的单位面积负载量M(单位：mg/cm 2)为10～50，从而能够控制化成产气的量，兼顾提高电芯的体积能量密度。
另外，在任意实施方式中，调节负极极片的比表面积S(单位：m 2/g)为0.5～5，能够进一步控制化成气体的量的同时，提高电芯的体积能量密度。
另外，在任意实施方式中，控制电极组件的化成产气排气速率因子β(L/Ah)的范围至0.06≤β≤0.1，从而能够兼顾化成气体的排出和电池的体积能量密度，能够在不降低电池的体积能量密度的情况下尽量增大产气预留空间，从而加速产气排出，保持化成后的界面。
另外，在任意实施方式中，负极活性材料的孔隙率为10％～40％， 既可以使负极活性材料层内部产生的气体快速扩散出来，同时电极组件也可以具有较高的体积能量密度和较低的电芯内阻。
另外，在任意实施方式中，电解液中还含有氟代碳酸乙烯酯和/或1,3-丙磺酸内酯。在保证二次电池具有高能量密度和低化成产气量的前提下，能够显著提高二次电池的高低温循环性能。
本申请的第二方面还提供一种电池模块，其包括本申请第一方面的二次电池。
本申请的第三方面还提供一种电池包，其包括本申请第一方面的二次电池或者第二方面的电池模块。
本申请的第四方面还提供一种用电装置，其包括本申请第一方面的二次电池、第二方面的电池模块或者第三方面的电池包。
本申请的电池模块、电池包和用电装置包括本申请第一方面的二次电池，因而至少具有与上述二次电池相同或类似的技术效果。
附图说明
图1是本申请一个实施方式的二次电池的示意图。
图2是图1所示的本申请一个实施方式的二次电池的分解图。
图3是本申请一个实施方式的电池模块的示意图。
图4是本申请一个实施方式的电池包的示意图。
图5是图4所示的本申请一个实施方式的电池包的分解图。
图6是本申请一个实施方式的用电装置的示意图。
附图标记说明：1电池包、2上箱体、3下箱体、4电池模块、5二次电池、51壳体、52电极组件、53顶盖组件。
具体实施方式
以下，适当地参照附图详细说明了本申请的二次电池、电池模块、电池包和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
本申请的一个实施方式中，提供一种二次电池。
[二次电池]
本申请的二次电池包括：电极组件；以及用于浸润该电极组件的电解液，其中，电极组件含有负极极片，该负极极片包括负极集流体和设置于负极集流体至少一个表面的负极活性材料层。通常情况下，二次电池还包括正极极片、以及设置在正极极片和负极极片之间的隔离膜。本申请的二次电池中使用含有下述通式(Ⅰ)所表示的化合物的电解液。
Figure PCTCN2022091749-appb-000007
通式(Ⅰ)中，A为单键或碳原子数1～5的烷基，R 1为
Figure PCTCN2022091749-appb-000008
Figure PCTCN2022091749-appb-000009
R 2为
Figure PCTCN2022091749-appb-000010
R 3为碳原子数1～3的烷基或烷氧基。
通式(Ⅰ)所示的化合物在电解液中的质量百分含量w(％)、负极极片的化成产气面积系数α和电极组件的化成产气排气速率因子β的数值满足下式(1)，
1.2≤0.1×w×α/β≤255      式(1)。
其中，α＝M×S           式(2)
式(2)中，M为负极活性材料在负极集流体的至少一个表面上的单位面积负载量，M的范围为5～100(mg/cm 2)；S为负极极片的比表面积(m 2/g)，S的范围为0.1～10(m 2/g)，
β＝10×V/Q      式(3)
式(3)中，Q为二次电池的额定容量(Ah)，V为电极组件的体积(L)，0.05≤β≤0.15。
申请人发现，本申请通过在二次电池中包含上述通式(I)所示的化合物，并将该化合物在电解液中的含量w、负极极片的化成产气面积系数α以及电极组件的化成产气排气速率因子β的数值控制在一定的关系范围内，从而能够减少化成产气量，加速化成产气排出，保持优良的化成界面，保证电池的安全性能，而且能够增大电池的体积能量密度，并且降低电芯内阻，使二次电池的电性能优良。
其机理尚不确定，但申请人认为如下。
通常如果想要显著提高电芯的体积能量密度，通过增加负极集流体中的负极活性材料的单位面积负载量M可以实现，但这样另一方面通常会使负极极片的比表面积S增加。而由于电解液在负极活性物质表面还原分解时会产生化成气体，并且该化成气体只能沿着负极和隔离膜的界面从电极组件的两端排出。因此负极极片的比表面积S越大，化成产气越多。如果不及时排出这些气体，气体会在负极与隔离膜的界面富集，形成气泡，阻断锂离子的传输，并最终会在负极表面形成黑斑和局部析锂，造成负极界面不良，容量发挥异常，并产生电池安全问题。
上述的化成气体从电极组件的两端排出后，会首先填充二次电池的产气预留空间，然后再从注液口排出，但气体排出速度有限，当化成气体充满产气预留空间时，新产生的化成气体难以从负极和隔膜界面排出，从而导致界面恶化。通常电极组件的体积V主要由结构件体积、活性材料体积和产气预留体积三部分组成，其中活性材料的体积一般直接决定二次电池的额定容量Q。在结构件体积固定的情况下，增大电极组件的体积与电 池额定容量的比值(V/Q)可增加产气预留空间，加速化成气体快速排出从而有利于保持化成后的界面。因此，作为减少化成气体在负极与隔离膜的界面富集的方法之一就是增大电极组件的体积与电池额定容量的比值(V/Q)，但是V/Q的增大又会导致电池的体积能量密度降低，从而降低电池包的成组效率，进而降低整个电池包的能量密度。
另外，作为减少化成气体在负极与隔离膜的界面富集的另一个方法是减少化成气体的产气量。申请人发现，上述通式(Ⅰ)所示的化合物作为一种电解液添加剂，还原电位比常规溶剂高，化成时可优先于溶剂在负极表面还原，抑制电解液溶剂在负极表面的还原分解，从而减少了电解液溶剂的还原分解的产气量。而且通式(Ⅰ)所示的化合物在负极表面还原形成含硫的有机物包覆层，不产生气体产物，因而不存在添加剂的还原分解产气。因此通式(Ⅰ)所示的化合物是一种高效的抑制电芯化成产气的电解液添加剂，通过在二次电池的电解液中添加通式(Ⅰ)所示的化合物作为添加剂可以显著控制化成产气量，维持电解液与负极活性物质的接触界面状态良好。因此，将含有通式(Ⅰ)所示的化合物的电解液应用于高能量密度电芯，可以在一定程度上兼顾高能量密度与化成界面优良。但是，在研究中发现，过多的通式(Ⅰ)所示的化合物会在负极表面形成较厚的保护膜，从而恶化锂离子在负极界面的传输速度，导致电芯内阻增加，影响二次电池的电性能。
综合以上，如果想要兼顾二次电池的高能量密度、优良的负极化成界面质量以及较低的电芯内阻以得到综合性能优异的二次电池，需要平衡控制通式(Ⅰ)所示的化合物的用量、负极集流体中的负极活性材料的单位面积负载量M、负极极片的比表面积S、以及电极组件的体积V与二次电池额定容量Q的比值。
在本申请中定义化成产气面积系数α＝M×S。其中，M为负极活性材料在负极集流体的至少一个表面上的单位面积负载量(单位：mg/cm 2)；S为负极极片的比表面积(单位：m 2/g)。定义电极组件的排气速率因子β＝10×V/Q。其中，V为电极组件的体积(单位：L)，Q为电极组件的容量(单位：Ah)。
申请人通过研究发现，电解液中通式(Ⅰ)所示的化合物的质量百分比w与化成产气面积系数α和排气速率因子β共同作用，对电芯的负极化成界面质量、体积能量密度和电芯内阻产生影响。进一步研究发现，当通式(Ⅰ)所示的化合物在电解液中的质量占比w、化成产气面积系数α和排气路径系数β满足关系式1.2≤0.1×w×α/β≤255时，既可以保证有足够的通式(Ⅰ)所示的化合物抑制化成产气，获得良好的化成界面，也能保证电芯具有高的能量密度。
在一些实施方式中，可选通式(Ⅰ)所示的化合物在电解液中的质量占比w、化成产气面积系数α和排气路径系数β满足关系式：5≤0.1×w×α/β≤128。当0.1×w×α/β的范围在上述范围内，能够减少化成产气量以使化成界面优良，更好地兼顾电芯的高能量密度及低内芯电阻。
在一些实施方式中，本申请的二次电池中，控制化成产气排气速率因子β范围为0.05≤β≤0.15。一般来说，β越小，产气预留空间越小，电极组件的体积能量密度越高；但β过小会导致预留空间过小，不利于存储过程中化成产气从界面排出，进而恶化界面，加速容量衰减。
在一些实施方式中，可选地，β范围为0.06≤β≤0.1。当β的范围在上述范围内，能够维持负极活性材料界面良好，进一步兼顾体积能量密度。
本申请提出的理论关系式并不仅限于适用于一种电池结构，当因为 其它需求改变电池外包装、电池的形状、改变电剂组件的组装方式(如叠片、卷绕等)等时，该理论关系式仍适用。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解液。
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1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和顶盖组件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，顶盖组件53能够盖设于开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔内。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。
[电解液]
电解液在正极极片和负极极片之间起到传导离子的作用，包含电解质盐、有机溶剂和有机添加剂。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，电解质采用电解液。电解液中包含下述通式(Ⅰ)所示的化合物，
Figure PCTCN2022091749-appb-000011
通式(Ⅰ)中，A为单键或碳原子数1～5的烷基，R 1为
Figure PCTCN2022091749-appb-000012
Figure PCTCN2022091749-appb-000013
R 2为
Figure PCTCN2022091749-appb-000014
其中R 3为碳原子数1～3的烷基或烷氧基。
上述通式(Ⅰ)所示的化合物不仅能优先于电解液溶剂在负极表面还原，降低溶剂还原分解产气，而且其本身还原不会有气体产物。
在一些实施方式中，该通式(Ⅰ)所示的化合物选自如下化合物1-16中的至少一种。
Figure PCTCN2022091749-appb-000015
Figure PCTCN2022091749-appb-000016
在一些实施方式中，通式(Ⅰ)所示的化合物在电解液中的质量占比w(单位：％)的数值范围为0.05～10，可选为0.2～5。通过将通式(Ⅰ)所示的化合物的含量范围控制在上述范围内，能够起到一定的抑制化成产气的作用，从而获得良好的化成界面，另一方面控制了通式(Ⅰ)所示的化合物的用量，从而保持二次电池的较低的常温内阻。
在一些实施方式中，本申请的电解液中包含的有机溶剂可根据实际需求进行选择，具体地，可包括链状碳酸酯、环状碳酸酯、羧酸酯中的一种或几种。其中，链状碳酸酯、环状碳酸酯、羧酸酯的种类没有具体的限制，可根据实际需求进行选择。可选地，电解液中的有机溶剂可包括碳酸二乙酯、碳酸二丙酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、γ-丁内酯、甲酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸甲酯、四氢呋喃中的一种或几种。
在一些实施方式中，本申请的电解液中还可进一步包含作为其它添加剂的选自含有不饱和键的环状碳酸酯化合物、卤素取代的环状碳酸酯化合物、亚硫酸酯化合物、磺酸内酯化合物、二磺酸化合物、腈化合物、芳香化合物、异氰酸酯化合物、磷腈化合物、环状酸酐化合物、亚磷酸酯化 合物、磷酸酯化合物、硼酸酯化合物、羧酸酯化合物中的至少一种。在保证二次电池具有高能量密度和低化成产气量的前提下，能够优化电芯性能，提高二次电池的高低温循环性能。
在一些实施方式中，电解液中包含氟代碳酸乙烯酯(FEC)、1，3-丙磺酸内酯(PS)等，当在电解液中添加额外的氟代碳酸乙烯酯(FEC)和/或1，3-丙磺酸内酯(PS)时，在保证二次电池具有高能量密度和低化成产气量的前提下，能够进一步降低电芯内阻，并显著提高二次电池的高低温循环性能。
在一些实施方式中，本申请的电解质盐的种类没有特别的限制，可根据实际需求进行选择。具体地，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
[负极极片]
本申请中，负极极片包括负极集流体以及设置于负极集流体上且包括负极活性材料的上的负极膜层，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。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极 活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，本申请的二次电池中，控制负极活性材料的单位面积负载量M(单位：mg/cm 2)的范围为5～100，负极极片的比表面积S(单位：m 2/g)的范围为0.1～10。如果负极活性材料的单位面积负载量M过低，会降低电池的能量密度；而过高会降低材料内部的锂离子传输速率，影响动力学性能。另外，如果负极极片的比表面积S过小会降低电化学反应面积，需要进一步降低负载量才能维持充电能力，而过大则化成产气量大导致界面恶化。
在一些实施方式中，可选M为10～50(mg/cm 2)，能够控制化成产气的量，保证化成后满充界面良好，进而能够兼顾提高电芯的体积能量密度和降低电芯内阻。
在一些实施方式中，可选S为0.5～5(m 2/g)。能够进一步控制化成产气的量，保证化成后满充界面良好，进而能够兼顾提高电芯的体积能量密度的同时降低电芯内阻。
在一些实施方式中，负极活性材料层的孔隙率为10％～40％，负极活性材料层的孔隙率越大，化成气体从负极活性材料层内部扩散到负极与隔离膜的界面的路径就越多越通畅，越不容易出现界面黑斑，但另一方面会导致电极组件的体积能量密度降低；负极活性材料层的孔隙率越小，化成气体从负极活性材料层内部扩散到负极与隔离膜的界面的路径就越少，气体排出速度越慢，更容易出现界面黑斑。通过将负极活性材料层的孔隙率限定为10％～40％，既可以使负极活性材料层内部产生的气体快速扩散出来，保证化成后满充界面良好，同时电极组件也可以具有较高的体积能量密度和较低的电芯内阻。
在一些实施方式中，本申请中的负极活性材料层还可包括导电剂、粘结剂以及其它可选助剂，其中，导电剂以及粘结剂的种类和含量不受具体的限制，可根据实际需求进行选择。负极活性材料层通常是由负极浆料涂布干燥而成的。负极浆料通常是将负极活性材料以及可选的导电剂和粘结剂等分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水。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以上。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)中的一种以上。其它可选助剂例如是增稠剂(如羧甲基纤维素钠(CMC-Na)等。
在一些实施方式中，负极集流体的种类也不受具体的限制，可根据实际需求进行选择。负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基材和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚苯乙烯、聚乙烯等的基材)上而形成。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极材料设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。例 如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基材和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(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，但本申请并不限定于这些材料。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四 氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
另外，以下适当参照附图对本申请的电池模块、电池包和装置进行说明。
[电池模块]
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
[电池包]
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量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4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
[用电装置]
另外，本申请还提供一种用电装置，该用电装置包括本申请提供的二次电池、电池模块、或电池包中的一种以上。本申请提供的二次电池、电池模块、或电池包可以用作装置的电源，也可以用作装置的能量存储单元。本申请的用电装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
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6是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
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。本申请实施例中各成分的含量，如果没有特别说明，均以质量计。
实施例1～24和对比例1～9的二次电池均按照下述方法制备。
(1)正极极片的制备
将正极活性材料LiNi 0.8Mn 0.1Co 0.1O 2、导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按重量比94:3:3加入到溶剂N-甲基吡咯烷酮(NMP)中，混合均匀后得到正极浆料，将正极浆料涂覆在正极集流体铝箔上，经过烘干、冷压、分切等工序得到正极极片。
(2)负极极片的制备
将负极活性物质人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC-Na)按照重量比95:2:2:1加入到 溶剂去离子水中，混合均匀后得到负极浆料，将负极浆料涂覆在负极集流体铜箔上，经过烘干、冷压、分切等工序得到负极极片，其中，负极极片参数分别如表1所示。
(3)电解液的制备
在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入1mol/L LiPF 6溶解于有机溶剂中，加入表1中所示种类和用量的通式(Ⅰ)所示的化合物添加剂或其它添加剂，搅拌均匀，得到电解液。
(4)隔离膜的制备
使用聚丙烯膜作为隔离膜。
(5)二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜位于正极极片和负极极片之间，然后卷绕得到电极组件；将电极组件置于电池壳体中，干燥后注入电解液，再经过化成、静置等工艺制得二次电池。
对各二次电池按照下述方法进行评价和测试。
1、负极极片相关参数测试
1-1)负极极片比表面积S的测试
将所有实施例和对比例的负极极片上的负极活性材料用刀片刮去下来，然后参照标准GB/T 21650.2-2008进行测试。具体数值参照表1。
1-2)负极极片孔隙率的测试
将负极极片冲切成直径为10cm的小圆片，利用千分尺测量厚度，计算表观体积V1，然后参照标准GB/T 24586-2009，采用气体置换法测量 真实体积V2，则孔隙率＝(V1-V2)/V1×100％。上述的负极极片为负极集流体设有负极活性材料的极片，该负极极片的孔隙率也就是负极活性材料层的孔隙率。该负极极片的孔隙率具体数值参照表3。
2、二次电池性能测试
2-1)化成后满充界面评价
将组装好的电池在45℃下静置120min，然后抽真空至-80kPa，接着0.02C恒流充电至3.4V；静置5min后，再0.1C恒流充电至3.75V，卸负压恢复常压。最后0.5C充电至4.2V，直至满充。随后将满充电芯拆解，观察评价负极界面是否有黑斑和析锂情况，并将结果分别示于表2。
2-2)体积、体积能量密度测试
在25℃下，将二次电池以1C恒流充电至4.3V，然后以4.3V恒压充电至电流小于0.05C，然后再以0.33C放电到2.8V，得到放电能量E。利用游标卡尺测量电池的长宽高，计算得到体积V，则体积能量密度＝E/V，将结果分别示于下表2。
2-3)电芯内阻测试
将电芯的电量调整到50％SOC，然后用交流内阻测试仪测试内阻，并将结果分别示于下表2。
2-4)二次电池的25℃循环性能测试
在25℃下，将二次电池以1C恒流充电至4.3V，然后以4.3V恒压充电至电流小于0.05C，然后将二次电池以1C恒流放电至2.8V，此为一个充放电过程。如此反复进行充电和放电，按照下述式(5)计算二次电池循环1000次后的容量保持率，并将结果示于表2。
二次电池25℃循环1000次后的容量保持率(％)＝(第1000次循 环的放电容量/首次循环的放电容量)×100％式(5)
2-5)二次电池的45℃循环性能测试
在45℃下，将二次电池以1C恒流充电至4.3V，然后以4.3V恒压充电至电流小于0.05C，然后将二次电池以1C恒流放电至2.8V，此为一个充放电过程。如此反复进行充电和放电，按照下述式(6)计算二次电池循环800次后的容量保持率，并将结果示于表2。
二次电池45℃循环800次后的容量保持率(％)＝(第800次循环的放电容量/首次循环的放电容量)×100％式(6)
表1：二次电池相关参数
Figure PCTCN2022091749-appb-000017
表2：二次电池性能测试表
Figure PCTCN2022091749-appb-000018
由表1和表2可知，在添加有含通式(Ⅰ)所示的化合物的电解液的实施例1-19中，通过控制负极极片的比表面积和负极活性材料的负载量在规定的范围内，从而优化化成界面，同时可兼顾提高体积能量密度和降低电芯内阻。另外，由表1和表2可知，在壳体体积固定的情况下，负极活性材料的负载量同时还影响电芯的额定容量和电极组件的排气速率因子 β，因此，通过控制负极极片的比表面积S、负载量M以及通式(Ⅰ)所示的化合物的添加量w，从而调节0.1×w×α/β的数值在1.2～255的范围内，从而可获得高的体积能量密度，并能保证有足够的通式(Ⅰ)所示的化合物抑制化成产气，获得良好的化成界面，同时通式(Ⅰ)所示的化合物的用量适中，保证二次电池的常温内阻良好。
相比之下，未添加通式(Ⅰ)所示的化合物的比较例7～9中，比较例7中由于负极活性物质的负载量小，因此虽然没有向溶剂中添加通式(Ⅰ)所示的化合物添加剂，其化成界面没有产生黑斑和析锂，但是其电芯的体积能量密度极低，电芯内阻较高，电池性能不好。比较例8中，与实施例4相比其负极极片的比表面积、负载量以及电极组件的壳体体积和电芯额定容量都一致，但是由于没有向溶剂中添加添加剂，因此与实施例相比化成时产生大量气体，严重地破坏了界面，在化成后满充截面上产生大量黑斑和局部析锂。另外，在比较例9中，使用了相关技术中使用的VC(碳酸亚乙烯酯)作为添加剂，其能抑制电解液溶剂还原来降低化成产气。但是VC本身会还原分解生成气体产物，导致改善效果不显著，并且严重恶化电芯内阻。在负极活性材料层的负载量大，电极组件体积与二次电池额定容量的比值小的高能量密度电芯设计中，若不及时排出化成产气将会显著影响化成界面，会导致黑斑和析锂，并影响电芯容量发挥。
表3：负极活性材料层的孔隙率对电池性能的影响
Figure PCTCN2022091749-appb-000019
表3中示出与实施例3具有相同的负极极片的比表面积S、负载量M以及电极组件的壳体体积但是改变了所使用的负极材料层的孔隙率的实施例20～24。由表3的结果可知，随着负极活性材料层的孔隙率的增大，由于化成气体从负极活性材料层内部扩散到负极与隔离膜的界面的路径增多因此越通畅，越不容易出现界面黑斑，但负极活性材料层的孔隙率的增大另一方面会导致电极组件的体积能量密度降低。负极活性材料层的孔隙率越小，化成气体从负极活性材料层内部扩散到负极与隔离膜的界面的路径就越少，气体排出速度越慢，更容易出现界面黑斑。因此，通过控制负极活性材料层的孔隙率为10％～40％，从而既可以使负极活性材料层内部产生的气体快速扩散出来，同时电极组件也可以具有较高的体积能量密度和较低的电芯内阻。
表4：部分实施例和对比例二次电池相关参数和性能测试表
Figure PCTCN2022091749-appb-000020
Figure PCTCN2022091749-appb-000021
由表4可以看出，在实施例3、10-14中，加入合适含量的通式(Ⅰ)所示的化合物的电解液并调节0.1×w×α/β在1.2～255的范围内，不仅能够兼顾高的体积能量密度和低电芯内阻并减少化成气体改善化成界面，而且还能够改善电芯常温和高温循环性能，这主要是由于化成界面得到显著改善，使得负极界面更加稳定。另外，实施例15、16中，在添加通式(Ⅰ)所示的化合物的基础上进一步添加剂FEC和PS，使其在负极成膜，能够进一步提高负极界面的稳定性，从而更进一步改善常温和高温循环性能。

Claims (12)

  1. 一种二次电池，包括：
    电极组件，其包含负极极片，所述负极极片包含负极集流体和设置于所述负极集流体的至少一个表面的负极活性材料；
    电解液，其含有下述通式(Ⅰ)所示的化合物，
    Figure PCTCN2022091749-appb-100001
    通式(Ⅰ)中，A为单键或碳原子数1～5的烷基，R 1为
    Figure PCTCN2022091749-appb-100002
    Figure PCTCN2022091749-appb-100003
    R 2为
    Figure PCTCN2022091749-appb-100004
    其中，R3为碳原子数1～3的烷基或烷氧基，
    所述通式(Ⅰ)所示的化合物在所述电解液中的质量百分含量w、所述负极极片的化成产气面积系数α和所述电极组件的化成产气排气速率因子β的数值满足下式(1)，其中w的单位为％，
    1.2≤0.1×w×α/β≤255  式(1)
    其中，α＝M×S  式(2)，
    式(2)中，M为所述负极活性材料在所述负极集流体的至少一个表面上的单位面积负载量，单位为mg/cm 2，所述M的数值范围为5～100；S为所述负极极片的比表面积，单位为m 2/g，所述S的数值范围为0.1～10，
    β＝10×V/Q  式(3)，
    式(3)中，Q为所述二次电池的额定容量，单位为Ah；V为所述电极组件的体积，单位为L，所述β的数值满足：0.05≤β≤0.15。
  2. 根据权利要求1所述的二次电池，其中，
    所述通式(Ⅰ)所示的化合物为选自以下化合物1～16中的至少一种，
    Figure PCTCN2022091749-appb-100005
  3. 根据权利要求1或2所述的二次电池，其中，
    所述通式(Ⅰ)所示的化合物在所述电解液中的质量百分含量w、所述化成产气面积系数α和所述化成产气排气速率因子β的数值满足下式，
    5≤0.1×w×α/β≤128。
  4. 根据权利要求1～3中任一项所述的二次电池，其中，
    所述w的数值范围为0.05～10，可选为0.2～5，所述w的单位为％。
  5. 根据权利要求1～4中任一项所述的二次电池，其中，
    所述M的数值范围为10～50，所述M的单位为mg/cm 2。
  6. 根据权利要求1～5中任一项所述的二次电池，其中，
    所述S的范围为0.5～5，所述S的单位为m 2/g。
  7. 根据权利要求1～6中任一项所述的二次电池，其中，
    所述β的数值满足：0.06≤β≤0.1。
  8. 根据权利要求1～7中任一项所述的二次电池，其中，
    所述负极极片的孔隙率为10％～40％。
  9. 根据权利要求1～8中任一项所述的二次电池，其中，
    所述电解液中还含有氟代碳酸乙烯酯和/或1，3-丙磺酸内酯。
  10. 一种电池模块，
    包括权利要求1～9中任一项所述的二次电池。
  11. 一种电池包，包括权利要求1～9中任一项所述的二次电池或权利要求10所述的电池模块。
  12. 一种用电装置，
    包括权利要求1～9中任一项所述的二次电池、权利要求10所述的电池模块或权利要求11所述的电池包中的至少一种。
PCT/CN2022/091749 2021-07-31 2022-05-09 二次电池、电池模块、电池包及用电装置 WO2023010927A1 (zh)

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