WO2023236007A1 - Solution électrolytique, batterie secondaire au lithium la comprenant, module de batterie, bloc-batterie et appareil électrique - Google Patents

Solution électrolytique, batterie secondaire au lithium la comprenant, module de batterie, bloc-batterie et appareil électrique Download PDF

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WO2023236007A1
WO2023236007A1 PCT/CN2022/097115 CN2022097115W WO2023236007A1 WO 2023236007 A1 WO2023236007 A1 WO 2023236007A1 CN 2022097115 W CN2022097115 W CN 2022097115W WO 2023236007 A1 WO2023236007 A1 WO 2023236007A1
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electrolyte
lithium
battery
lithium secondary
diluent
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PCT/CN2022/097115
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English (en)
Chinese (zh)
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范玉磊
葛销明
陈宇杰
王慢慢
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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 CN202280069714.0A priority Critical patent/CN118104030A/zh
Priority to PCT/CN2022/097115 priority patent/WO2023236007A1/fr
Publication of WO2023236007A1 publication Critical patent/WO2023236007A1/fr

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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
    • 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
    • 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
    • H01M10/0569—Liquid materials characterised by the solvents

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to an electrolyte and a lithium secondary battery, a battery module, a battery pack, and an electrical device containing the electrolyte.
  • lithium secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric Automobiles, military equipment, aerospace and other fields.
  • energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric Automobiles, military equipment, aerospace and other fields.
  • lithium secondary batteries have achieved great development, higher requirements have been placed on their cycle performance and safety performance.
  • This application was made in view of the above problems, and its purpose is to provide an electrolyte that can effectively improve the cycle performance and capacity retention rate of lithium secondary batteries, and to provide lithium secondary batteries and battery modules including the electrolyte of the application. , battery packs and electrical devices.
  • a first aspect of the present application provides an electrolyte solution, which contains an electrolyte lithium salt, an organic solvent that dissolves the electrolyte lithium salt, and a diluent, the diluent and the organic solvent that dissolves the electrolyte lithium salt.
  • the solvents are different, and the diluent is selected from C 6 -C 17 alkanes, optionally C 8 -C 15 alkanes, and further optionally C 8 -C 13 alkanes.
  • the electrolyte containing diluent of the present application is beneficial to reducing the viscosity of the electrolyte, improving the conductivity of the electrolyte and the transmission capacity of lithium ions in the electrolyte, and obtaining a stable SEI film mainly composed of inorganic components, thereby Suppresses the precipitation of lithium and improves the cycle capability and capacity retention rate of lithium secondary batteries.
  • the diluent in the electrolyte of the present application is n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane or n-octane.
  • the diluent is at least one of n-octane, n-nonane, n-decane, n-undecane, n-dodecane, and n-tridecane.
  • the type of diluent is further limited, so that the electrolyte can form a good solvation structure and obtain an SEI film with better stability.
  • the ratio of the mass W1 of the organic solvent to the mass W2 of the diluent is (0.1 ⁇ 12):1, optionally (0.14 ⁇ 11.10):1, and optionally ( 0.14 ⁇ 1.23):1.
  • the solvation structure is changed, an SEI film mainly composed of inorganic components is formed, and the stability of the SEI film is improved.
  • the ratio of the mass W1 of the organic solvent: the mass W2 of the diluent: the mass W3 of the electrolyte lithium salt is (0.05 ⁇ 2.5): (0.15 ⁇ 5.55): 1, which can be Selected as (0.09 ⁇ 1.67): (0.30 ⁇ 5.41): 1.
  • the electrolyte lithium salt can be fully ionized and improve the conductivity of the battery; on the other hand, it is conducive to the formation of stable inorganic components (
  • the SEI film based on lithium salt anions (such as fluoride ions) improves the cycle performance of the battery.
  • the electrolyte lithium salt includes: at least one of lithium hexafluorophosphate, lithium bisfluorosulfonimide, lithium bistrifluoromethylsulfonimide, and lithium difluoroxalate borate. , optionally lithium bisfluorosulfonyl imide.
  • the molar concentration of lithium bisfluorosulfonimide in the electrolyte is 0.05-5mol/l, optionally 0.1-4mol/l, and optionally 0.5- 4 mol/l, further optionally 1-3 mol/l, based on the total volume of the electrolyte. This is beneficial to improving the viscosity and conductivity of the electrolyte and improving the cycle performance of the battery.
  • the organic solvent includes at least one of carbonates or ethers; optionally, the organic solvent includes: fluorinated ethylene carbonate, ethylene carbonate , propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran or 1,3-dioxolane At least one of; further optionally ethylene glycol dimethyl ether.
  • the electrolyte lithium salt is dissociated under the action of the organic solvent, and the fluidity of the electrolyte is improved at the same time.
  • the electrolyte of the present application also includes additives, the content of which is 0.1-5%, optionally 0.5-3%, based on the total mass of the electrolyte. This will help improve the stability of the SEI film and further improve the cycle performance of the battery.
  • the additives in the electrolyte of the present application include: lithium nitrate, lithium fluoride, lithium carbonate, lithium difluoroxalate, ethyl sulfate, 1,3-propanesultone, tris(trimethyl) At least one of tris(trimethylsilane)borate, trimethylsilane)phosphate, and trimethylmethoxysilane. This further improves the stability of the SEI film of the battery and improves the cycle performance of the battery.
  • a second aspect of the present application provides a lithium secondary battery, which includes the electrolyte of the first aspect of the present application.
  • a third aspect of the present application provides a battery module, which includes the lithium secondary battery of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery pack, which includes the battery module of the third aspect of the present application.
  • a fifth aspect of the present application provides an electrical device, which includes at least one of the lithium secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.
  • the electrolyte of the present application changes the solvation structure of the electrolyte by containing an alkane diluent, which is conducive to the formation of a more stable SEI film, improves the transmission capacity of lithium ions and the conductivity of the electrolyte, thereby making the electrolyte containing the present application Liquid lithium secondary batteries have significantly improved cycle performance.
  • the battery pack, battery module and electrical device provided by the present application also have significantly improved cycle performance.
  • Figure 1 is a scanning electron microscope image of the surface morphology of the negative electrode of the lithium secondary battery of Examples 1-8 of the present application after the 100th cycle.
  • Figure 2 is a scanning electron microscope image of the surface morphology of the negative electrode of the lithium secondary battery of Comparative Example 1 after the 100th cycle.
  • Figure 3 is a Coulombic efficiency test of the lithium secondary battery of Comparative Example 1.
  • Figure 4 is a Coulombic efficiency test of the lithium secondary batteries in Examples 1-8 of the present application.
  • FIG. 5 is a schematic diagram of a lithium secondary battery according to an embodiment of the present application.
  • FIG. 6 is an exploded view of the lithium secondary battery according to the embodiment of the present application shown in FIG. 5 .
  • FIG. 7 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 8 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 9 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 8 .
  • FIG. 10 is a schematic diagram of a power consumption device using a lithium secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-6.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • electrolytes used in lithium secondary batteries mainly contain lithium salts and organic solvents.
  • lithium salt and organic solvent will react on the surface of the negative electrode to form a deposit with organic matter as the main component, that is, the SEI film.
  • This film is crucial to the electrochemical performance of the lithium battery.
  • the SEI film formed is unstable and will dissolve in the electrolyte, causing damage to the SEI film structure and greatly increasing the direct contact area between the negative electrode and the electrolyte.
  • the occurrence of side reactions mainly the deposition of by-products of electrolyte decomposition on the surface of the negative electrode and the production of gas from the electrolyte ultimately deteriorates the cycle performance and safety performance of the battery.
  • the inventor developed an electrolyte system containing a diluent, which forms a solvation structure with a lower concentration of organic solvent components and a higher concentration of lithium salt anion components (such as fluoride ions), which can promote more lithium.
  • Salt anions participate in film formation, forming a stable SEI film mainly composed of inorganic components, thus improving the cycle performance and safety performance of lithium secondary batteries.
  • a first aspect of the application provides an electrolyte solution, which includes an electrolyte lithium salt, an organic solvent that dissolves the electrolyte lithium salt, and a diluent, the diluent is different from the organic solvent that dissolves the electrolyte lithium salt, and the The diluent is selected from C 6 -C 17 alkanes, optionally C 8 -C 15 alkanes, further optionally C 8 -C 13 alkanes.
  • organic solvent that dissolves the electrolyte lithium salt refers to dissociating the electrolyte lithium salt and meeting the conductivity requirements required by the battery.
  • C 6 -C 17 alkanes refers to straight-chain, branched-chain saturated alkanes having 6 to 17 carbon atoms. Examples include, but are not limited to, n-hexane and its isomers, n-heptane and its isomers, n-octane and its isomers, n-nonane and its isomers, n- Decane and its isomers, n-undecane and its isomers, n-dodecane and its isomers, n-tridecane and its isomers, n-tetradecane and its isomers, or n-pentadecane and its isomers.
  • n-hexane and its isomers refer to n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane alkyl.
  • C 8 -C 15 alkanes which refers to straight-chain, branched-chain saturated alkanes having 8 to 15 carbon atoms.
  • C 8 -C 13 alkanes which refers to straight-chain, branched-chain saturated alkanes having 8 to 13 carbon atoms.
  • the organic solvent in the electrolyte can be diluted, the solvation structure is changed, and the degree of participation of the anions of the lithium salt in solvation is relatively increased. Therefore, even if Under low-concentration lithium salt conditions, a stable SEI film composed mainly of inorganic components can be formed, thereby solving the problem of lithium precipitation and improving the cycle performance of lithium secondary batteries; on the other hand, it reduces the electrolyte concentration The viscosity, lithium ion transport capacity and electrolyte conductivity are significantly improved.
  • the diluent in the electrolyte, is n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane or n-decane.
  • pentane optionally, the diluent is at least one of n-octane, n-nonane, n-decane, n-undecane, n-dodecane, and n-tridecane.
  • the composition of the electrolyte can be further optimized so that the electrolyte forms a good solvation structure.
  • This structure promotes the electrolyte to form a more stable SEI film on the surface of the positive and negative electrodes, which not only can Avoiding or reducing electrolyte loss and inhibiting the growth of lithium dendrites can result in batteries with significantly improved cycle performance.
  • the ratio of the mass W1 of the organic solvent contained in the electrolyte to the mass W2 of the diluent is (0.1 ⁇ 12):1, optionally (0.14 ⁇ 11.10):1, and optionally (0.14 ⁇ 11.10):1. 1.23): 1.
  • the volume ratio of the organic solvent to the diluent is 9:1 to 1:9. Further optionally, the volume ratio of the organic solvent to the diluent is 1:1 to 9:1.
  • the solvation structure is changed, an SEI film mainly composed of inorganic components is formed, and the stability of the SEI film is improved.
  • the ratio of the mass W1 of the organic solvent contained in the electrolyte: the mass W2 of the diluent: the mass W3 of the electrolyte lithium salt is (0.05 ⁇ 2.5): (0.15 ⁇ 5.55): 1, optionally (0.09 ⁇ 1.67): (0.30 ⁇ 5.41): 1.
  • the electrolyte lithium salt includes: lithium hexafluorophosphate (LiPF 6 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethylsulfonyl imide (LiTFSI), At least one of lithium fluorosulfonyl borate (LiDFOB) can be selected from lithium bisfluorosulfonyl imide.
  • LiPF 6 lithium hexafluorophosphate
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethylsulfonyl imide
  • LiDFOB lithium fluorosulfonyl borate
  • the molar concentration of lithium bisfluorosulfonimide in the electrolyte is 0.05-5mol/l, optionally 0.1-4mol/l, optionally 0.5-4mol/l, further optionally: 1-3 mol/l, based on the total volume of the electrolyte.
  • the lithium ion content of the electrolyte lithium salt By further limiting the lithium ion content of the electrolyte lithium salt, it is beneficial to improve the viscosity and conductivity of the electrolyte and improve the cycle performance of the battery.
  • the organic solvent includes at least one of carbonates or ethers; optionally, the organic solvent includes: fluorinated ethylene carbonate, ethylene carbonate Ester, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene glycol dimethyl ether, diglyme, tetraglyme, tetrahydrofuran or 1,3-dioxolane At least one of them; further optionally, ethylene glycol dimethyl ether.
  • the function of these organic solvents is to dissociate lithium salts and meet the conductivity requirements of the battery.
  • carbonate refers to a compound in which the hydrogen atoms of the two hydroxyl groups (-OH) in the carbonic acid molecule are replaced by alkyl groups (R 1 , R 2 ), with the general formula R 1 O-CO-OR 2 , wherein R 1 and R 2 can be the same or different selected from C 1 -C 4 -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl group, which is an open-chain carbonate, examples of which include but are not limited to dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.; or R 1 and R 2 are connected to form an alkylene group such as C 1 -C 4 alkylene
  • the group (-CH 2 CH 2 - or -CH 2 CH 2 CH 2 ) is a cyclic carbonate, examples of which include but are not limited to ethylene carbon
  • ether refers to the product of an alcohol in which the hydrogen in the hydroxyl group is replaced by a hydrocarbyl or alkylene group.
  • examples include, but are not limited to, polyglycol diethers, ethylene oxide, propylene oxide, tetrahydrofuran, dioxolane, etc.
  • the electrolyte contains an organic solvent with a mass fraction of 6.5% to 64%, a diluent with a mass fraction of 5.5% to 67%, and an electrolyte lithium salt with a mass fraction of 12% to 60%, based on the total electrolyte. Mass meter.
  • the mass fraction of the organic solvent contained in the electrolyte is 6.5% to 37%
  • the mass fraction of the diluent is 20% to 55%
  • the mass fraction of the electrolyte lithium salt is 33% to 36%, based on Total mass of electrolyte.
  • the electrolyte further includes additives, the mass fraction of the additives is 0.1% to 5%, optionally 0.5% to 3%, further optionally, the mass fraction of the additives is 1%, based on the electrolyte Total mass meter. This further improves the stability of the SEI film, thereby avoiding or reducing electrolyte loss and inhibiting the growth of lithium dendrites, and the cycle performance and safety performance of the battery are significantly improved.
  • additives in the electrolyte of the present application include lithium nitrate, lithium fluoride, lithium carbonate, lithium difluoroxalate, ethyl sulfate, 1,3-propanesultone, tris(trimethylsilane) ) at least one of phosphate, tris(trimethylsilane)borate, and trimethylmethoxysilane.
  • each of the above substances is regarded as an additive when its mass fraction is no more than 5% (based on the total mass of the electrolyte). As a result, the stability of the SEI film is further improved and the cycle performance of the battery is improved.
  • electrolyte of the present application can be used not only for lithium secondary batteries, but also for any other battery, battery module, battery pack or electrical device that needs to improve cycle performance.
  • the lithium secondary battery, battery module, battery pack and power consumption device of the present application are described below.
  • a lithium secondary battery which includes the electrolyte of the present application.
  • lithium secondary batteries typically include positive electrode plates, negative electrode plates, electrolytes and separators.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer. At least one of a meta-copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components 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 piece can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners, such as sodium carboxymethyl cellulose (CMC-Na), and the like.
  • auxiliaries such as thickeners, such as sodium carboxymethyl cellulose (CMC-Na), and the like.
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the preparation process of the negative electrode sheet includes: punching a 5-13 ⁇ m thick copper foil to obtain the negative electrode sheet.
  • the lithium secondary battery further includes a separator film.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play an isolation role.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the lithium secondary battery may include an outer package for packaging the positive electrode tab, the negative electrode tab, and the electrolyte.
  • the positive electrode sheet, the negative electrode sheet and the separator film can be laminated or rolled to form a laminated structure cell or a wound structure cell, and the cell is packaged in an outer package; the electrolyte can be electrolyte, and the electrolyte is infiltrated in the battery core.
  • the number of cells in a lithium secondary battery can be one or several, which can be adjusted according to needs.
  • the present application provides an electrode assembly.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the outer packaging can be used to package the above-mentioned electrode components and electrolytes.
  • the outer packaging of the lithium secondary battery may be a soft bag, such as a pouch-type soft bag.
  • the soft bag may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • the outer packaging of the lithium secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the present application provides a method for preparing a lithium secondary battery, in which the electrolyte provided in the first aspect of the present application is used.
  • the preparation of the lithium secondary battery may also include the step of assembling the negative electrode sheet, the positive electrode sheet and the electrolyte of the present application to form a lithium secondary battery.
  • the positive electrode piece, the isolation film, and the negative electrode piece can be wound or laminated in order, so that the isolation film plays an isolation role between the positive electrode piece and the negative electrode piece, thereby obtaining a battery core.
  • the battery core is placed in the outer package, electrolyte is injected and sealed to obtain a lithium secondary battery.
  • the battery margin of lithium secondary batteries is 90-95%.
  • the preparation of the lithium secondary battery may further include the step of preparing a positive electrode sheet.
  • the positive electrode active material, conductive agent and binder can be dispersed in a solvent (such as N-methylpyrrolidone, NMP for short) 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 piece is obtained.
  • a solvent such as N-methylpyrrolidone, NMP for short
  • the preparation of a lithium secondary battery includes the step of preparing a negative electrode sheet according to the method described herein.
  • FIG. 5 shows a lithium secondary battery 5 with a square structure as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the lithium secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the present application provides an electrical device, a battery module or a battery pack, wherein the electrical device, battery module or battery includes a lithium secondary battery as described in the present application or a battery as described in the present application. Lithium secondary battery prepared by the method.
  • secondary batteries can be assembled into battery modules, and the number of lithium secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 7 shows the battery module 4 as an example.
  • a plurality of lithium secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of lithium secondary batteries 5 can be fixed with fasteners.
  • the battery module 4 may further include a housing having an accommodation space in which a plurality of lithium secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the lithium secondary battery, battery module, or battery pack provided by the present application.
  • the lithium secondary battery, battery module, or battery pack can be used as a power source for an electric device, or as an energy storage unit of the electric device.
  • Electric devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric Trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • lithium secondary batteries, battery modules or battery packs can be selected according to its usage requirements.
  • FIG 10 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • This device is usually required to be thin and light, and a lithium secondary battery can be used as a power source.
  • the electrolyte of Example 1-1 refers to the electrolyte used in the preparation process of the lithium secondary battery of Example 1-1;
  • the positive electrode sheet of Example 1-1 refers to the electrolyte of Example 1-1.
  • the negative electrode sheet of Example 1-1 refers to the positive electrode sheet used in the preparation process of the lithium secondary battery of Example 1-1 ;
  • Separation film of Example 1-1 refers to the separation film used in the preparation process of the lithium secondary battery of Example 1-1;
  • Lithium secondary battery of Example 1-1 refers to the separation film used in the preparation process of the lithium secondary battery of Example 1-1 Lithium secondary battery prepared from -1 positive electrode, separator, negative electrode and electrolyte.
  • the total volume of the prepared electrolyte solution is 100 ml, in which the molar concentration of the lithium salt is 1.5 mol/l, based on the total mass of the electrolyte solution.
  • Lithium iron phosphate is evenly coated on the positive electrode current collector aluminum foil with a thickness of 13 ⁇ m.
  • the surface capacity of the electrode piece is 2.85mAh/cm 2
  • the rolling and punching area is 49.5mm*42mm.
  • a copper foil with a thickness of 8 ⁇ m is used as the negative electrode piece, and the area is punched into a size of 51mm*43.5mm.
  • a polypropylene film with a thickness of 9 ⁇ m was used as the isolation film.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 56.09g (64.70ml) ethylene glycol dimethyl ether (DME), and 6.50g (9.24ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 53.04g (61.18ml) ethylene glycol dimethyl ether (DME), and 8.81g (12.53ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 51.02g (58.84ml) ethylene glycol dimethyl ether (DME), and 10.34g (14.71ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 47.66g (54.97ml) ethylene glycol dimethyl ether (DME), and 12.88g (18.32ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 31.17g (35.95ml) ethylene glycol dimethyl ether (DME), and 25.27g (35.95ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 15.25g (17.59ml) ethylene glycol dimethyl ether (DME), and 37.09g (52.76ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 12.14g (14.00ml) ethylene glycol dimethyl ether (DME), and 39.38g (56.01ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 10.29g (11.87ml) ethylene glycol dimethyl ether (DME), and 40.74g (57.95ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 7.53g (8.69ml) ethylene glycol dimethyl ether (DME), and 42.76g (60.82ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm In the atmosphere glove box, add 28.06g LiFSI, 6.01g (6.93ml) ethylene glycol dimethyl ether (DME), and 43.87g (62.40ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolytic solution used in this example. liquid.
  • the total volume of the electrolyte is 100 ml, and the molar concentration of the electrolyte lithium salt is 1.5 mol/l, but the volume ratio of DME to n-octane Different, they are 9:1, 7:1, 5:1, 4:1, 3:1, 1:1, 1:3, 1:4, 1:5, 1:7, 1:9, as shown in the table 1 shown.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the total volume of the prepared electrolyte is 100 ml, in which the molar concentration of the electrolyte lithium salt is 1.0 mol/l.
  • the organic solvents used are ethylene carbonate and ethyl methyl carbonate.
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the glove box add 18.71g LiFSI, 13.87g (16.00ml) ethylene glycol dimethyl ether (DME), and 45.00g (64.01ml) n-octane respectively into the beaker, stir thoroughly and dissolve to obtain the electrolyte for this example. .
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the glove box add 37.41g LiFSI, 11.09g (12.79ml) ethylene glycol dimethyl ether (DME), and 35.96g (51.16ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolyte for this example. .
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the glove box add 9.35g LiFSI, 15.61g (18.00ml) ethylene glycol dimethyl ether (DME), and 50.62g (72.00ml) n-octane respectively into the beaker, stir thoroughly and dissolve to obtain the electrolyte for this example. .
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the glove box add 74.83g LiFSI, 6.87g (7.93ml) ethylene glycol dimethyl ether (DME), and 22.30g (31.72ml) n-octane respectively into the beaker. Stir thoroughly and dissolve to obtain the electrolyte for this example. .
  • Examples 2-1 to 2-5 the total volume of the electrolyte is 100 ml, the volume ratio of DME to n-octane is 1:4, and the molar concentrations of the electrolyte lithium salts are different, respectively 1, 2, 3, 0.5, 4mol/l, as shown in Table 2.
  • the preparation process of the lithium-ion battery is generally referred to that of Example 1-1.
  • the difference is that the preparation steps of the electrolyte are in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 0.1 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the total volume of the electrolyte is 100 ml
  • the volume ratio of DME to n-octane is 1:4
  • the molar concentration of the electrolyte lithium salt is 1.5 mol/l, but the dilution types are different. as shown in Table 3.
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation steps of the electrolyte are: argon gas with water content (H 2 O) ⁇ 10 ppm and oxygen content (O 2 ) ⁇ 10 ppm.
  • O 2 oxygen content
  • This embodiment uses electrolyte.
  • the preparation process of the lithium secondary battery is generally based on Example 4-1. The difference is that in the preparation step of the electrolyte, the types of additives are changed, as shown in Table 4.
  • the total volume of the electrolyte is 100 ml
  • the volume ratio of DME to n-octane is 1:4
  • the molar concentration of the electrolyte lithium salt is 1.5 mol/l
  • the mass fraction of the additive 1% based on the total mass of the electrolyte.
  • the types of additives are different, as shown in Table 4.
  • the preparation process of the lithium secondary battery is generally based on Example 1-1. The difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the preparation process of the lithium secondary battery is generally referred to Examples 1-8.
  • the difference is that the preparation of the negative electrode sheet is as follows:
  • the preparation process of the lithium secondary battery is generally based on Example 5-1, with the following differences:
  • Example 5-2 The preparation steps of the electrolyte of Example 5-2 are the same as those of Example 1-1, wherein the volume ratio of DME to n-octane is 9:1;
  • Example 5-3 The preparation steps of the electrolyte of Example 5-3 are the same as those of Example 1-11, wherein the volume ratio of DME to n-octane is 1:9.
  • the preparation process of the lithium secondary battery is generally based on Example 5-1, with the following differences:
  • Embodiment 5-4 The preparation steps of the electrolyte of Embodiment 5-4 are the same as those of Embodiment 3-2, wherein the diluent is n-decane;
  • Embodiment 5-5 The preparation steps of the electrolyte of Embodiment 5-5 are the same as those of Embodiment 3-4, wherein the diluent is n-dodecane;
  • Example 5-6 The preparation steps of the electrolyte of Example 5-6 are the same as those of Example 3-7, wherein the diluent is n-pentadecane.
  • the preparation process of the lithium secondary battery is generally based on Example 5-1. The difference is that the preparation steps of the electrolyte are: in an argon atmosphere with a water content (H 2 O) ⁇ 10 ppm and an oxygen content (O 2 ) ⁇ 10 ppm.
  • H 2 O water content
  • O 2 oxygen content
  • the total volume of the prepared electrolyte is 100 ml, the molar concentration of the electrolyte lithium salt is 1.0 mol/l, and the organic solvents used are ethylene carbonate and ethyl methyl carbonate.
  • the lithium secondary batteries of the above examples and comparative examples were cycled for 100 cycles, the lithium secondary batteries were disassembled and the surface morphology of the metallic lithium negative electrode plate was observed with a metallographic optical microscope (Axio Observer Z1M) magnified 1000 times. Observe whether lithium dendrites are formed.
  • the lithium secondary batteries of the above embodiments and comparative examples were charged to 3.7V with a constant current and voltage of 0.285mA/ cm2 , left to stand for 10 minutes, and then discharged to 2.5V with a constant current of 1mA/ cm2 to obtain
  • the Coulomb efficiency of the first cycle is the first Coulomb efficiency. Charge and discharge are repeated in this way to obtain the Coulombic efficiency of the 100th cycle.
  • the capacity retention rate is the ratio of the discharge capacity at a specified number of cycles to the first discharge capacity.
  • V1 represents the volume of the organic solvent
  • W1 represents the mass of the organic solvent
  • V2 represents the volume of the diluent
  • W2 represents the mass of the diluent
  • W3 represents the mass of the electrolyte lithium salt
  • A represents the mass ratio of the organic solvent to the diluent in the electrolyte (W1:W2)
  • B represents the mass ratio of the organic solvent, diluent, and electrolyte lithium salt in the electrolyte (W1:W2 :W3).
  • the secondary lithium batteries corresponding to the Examples in Tables 1 to 4 and Comparative Examples 1-3 are lithium metal batteries, and the secondary batteries corresponding to the Examples and Comparative Example 4 in Table 5 are lithium ion batteries.
  • Embodiment 2-5 of the present invention in Table 2 has higher first Coulombic efficiency and capacity retention rate than Comparative Example 1 in Table 1.
  • Embodiment 2-1 of the present invention in Table 2 has higher first-time Coulomb efficiency and capacity retention rate than Comparative Example 2 in Table 2.
  • Higher first coulombic efficiency, and significantly increased capacity retention This shows that under the condition that the electrolyte solution contains the same molar concentration of electrolyte lithium salt, compared with the electrolyte solution that does not contain a diluent (Comparative Examples 1 and 2), when the electrolyte solution of the present invention contains a diluent, the performance of the lithium metal battery is improved. Both first-time Coulombic efficiency and capacity retention are significantly improved.
  • the first cycle efficiency of the lithium metal battery is Higher than 92%, the capacity retention rates are all above 50%. Furthermore, when the diluent is a C 8 -C 13 alkane, the first cycle efficiency and capacity retention rate of the lithium metal battery are further improved.
  • the surface morphology of the lithium metal negative electrode in the lithium secondary battery of Examples 1-8 of the present application is shown in Figure 1, and the surface morphology of the lithium metal negative electrode in the lithium secondary battery of Comparative Example 1 is shown in Figure 2. It can be seen that the lithium dendrite growth of the lithium secondary battery according to the embodiment of the present application is suppressed.

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Abstract

L'invention concerne une solution électrolytique, comprenant un sel de lithium d'électrolyte, un solvant organique pour dissoudre le sel de lithium d'électrolyte, et un diluant, le diluant étant différent du solvant organique pour dissoudre le sel de lithium d'électrolyte, et le diluant étant choisi parmi un alcane en C6-C17. En ajoutant le diluant dans la solution électrolytique, la viscosité de la solution électrolytique est réduite, la conductivité de la solution électrolytique et la capacité de transmission d'ions lithium dans la solution électrolytique sont améliorées, et un film SEI stable composé principalement de composants inorganiques est obtenu, ce qui permet d'inhiber la précipitation du lithium, et d'améliorer la capacité de cycle et le rapport de rétention de capacité d'une batterie secondaire au lithium. La présente invention concerne en outre une batterie secondaire au lithium comprenant la solution électrolytique, un module de batterie, un bloc-batterie et un appareil électrique.
PCT/CN2022/097115 2022-06-06 2022-06-06 Solution électrolytique, batterie secondaire au lithium la comprenant, module de batterie, bloc-batterie et appareil électrique WO2023236007A1 (fr)

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PCT/CN2022/097115 WO2023236007A1 (fr) 2022-06-06 2022-06-06 Solution électrolytique, batterie secondaire au lithium la comprenant, module de batterie, bloc-batterie et appareil électrique

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CN110890592A (zh) * 2019-11-28 2020-03-17 华中科技大学 一种含芳香类化合物作为稀释剂的锂金属电池电解液
CN110911756A (zh) * 2019-11-28 2020-03-24 华中科技大学 一种稀释的混合锂盐的锂硫电池电解液
CN114583280A (zh) * 2020-11-30 2022-06-03 中国科学院大连化学物理研究所 一种锂金属电池电解液及其制备方法
CN112909339A (zh) * 2021-03-23 2021-06-04 深圳赛骄阳能源科技股份有限公司 一种碳酸丙烯酯基电解液及包含该电解液的锂离子电池

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