WO2023083148A1 - 一种锂离子电池 - Google Patents

一种锂离子电池 Download PDF

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Publication number
WO2023083148A1
WO2023083148A1 PCT/CN2022/130417 CN2022130417W WO2023083148A1 WO 2023083148 A1 WO2023083148 A1 WO 2023083148A1 CN 2022130417 W CN2022130417 W CN 2022130417W WO 2023083148 A1 WO2023083148 A1 WO 2023083148A1
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lithium
ion battery
battery according
electrolyte
negative electrode
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PCT/CN2022/130417
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English (en)
French (fr)
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郭盼龙
储霖
李素丽
陈伟平
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珠海冠宇电池股份有限公司
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Publication of WO2023083148A1 publication Critical patent/WO2023083148A1/zh
Priority to US18/398,833 priority Critical patent/US20240145762A1/en

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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
    • H01M10/05—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
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/0042—Four or more solvents
    • 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 disclosure belongs to the technical field of lithium-ion batteries, and in particular relates to a lithium-ion battery.
  • lithium-ion batteries have been a hot topic in the fields of scientific research and industry; increasing the energy density of lithium-ion batteries can significantly improve the performance of end products, such as higher endurance of smart electronic products. Improving the gram capacity of materials is the main means to increase the energy density of lithium-ion batteries.
  • the theoretical specific capacity of silicon (Si)-based negative electrode materials is as high as 4200mAh/g, and its lithium intercalation and desorption platform is more suitable, so it is an ideal high-capacity negative electrode material for lithium-ion batteries.
  • Si silicon
  • the volume expansion of Si reaches more than 300%, and the internal stress generated by the drastic volume change can easily lead to powdering and peeling of the electrode, thereby affecting the performance and cycle stability of the battery.
  • binders In order to improve the volume expansion of silicon-based anode materials, in addition to material modification from the silicon-based anode itself, the use of new binders with good flexibility and high bonding strength is also an effective means. Most of the currently commercialized binders have high bonding rigidity and low flexibility, so they are not effective in inhibiting the volume expansion of silicon negative electrodes, and the compatibility between the binder and the electrolyte is poor, and the bonding strength drops sharply in the electrolyte. .
  • the present disclosure provides a lithium-ion battery.
  • the lithium-ion battery has high energy density while having excellent cycle life and low cycle life. Expansion rate.
  • a kind of lithium ion battery, described lithium ion battery comprises positive pole, negative pole, diaphragm and non-aqueous electrolytic solution;
  • FEC fluoroethylene carbonate
  • PP propyl propionate
  • the negative electrode includes a binder, which is a polymer with a hydroxyl group in the side chain, and is a graft-copolymerized acrylic acid, acrylonitrile, acrylamide, acrylate, styrene, vinylimidazole, vinylpyridine , Sodium p-styrene sulfonate, etc., one or more graft copolymers.
  • a binder which is a polymer with a hydroxyl group in the side chain, and is a graft-copolymerized acrylic acid, acrylonitrile, acrylamide, acrylate, styrene, vinylimidazole, vinylpyridine , Sodium p-styrene sulfonate, etc., one or more graft copolymers.
  • the binder has a structure as shown in formula 1 or formula 2:
  • R 1 , R 3 , R 4 , R 5 , R 7 , R 8 are the same or different, and are independently selected from H, C 1-6 alkyl, preferably H, C 1-4 alkyl, such as H, methyl , ethyl, propyl;
  • R 2 and R 6 are the same or different, independently selected from carboxylic acid group, amide group, ester group, sulfonic acid group, phenyl group, imidazolyl group, nitrile group and other groups and related group derivative groups or multiple combinations;
  • x ranges from 1 to 1 million
  • y ranges from 100,000 to 1 million
  • z ranges from 1 to 1 million
  • a is 1 to 1 million
  • b is 100 to 1 million
  • c is 1 to 2000
  • d is 100 to 1 million
  • e is 0 to 2000.
  • the negative electrode includes a negative electrode active layer
  • the negative electrode active layer includes the binder
  • the weight of the binder in the negative electrode active layer accounts for A, and the range of A is 1wt%. ⁇ 30wt%, such as 1wt%, 2wt%, 3wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, preferably 3wt% ⁇ 30wt%.
  • the main function of the binder in the negative electrode of the present disclosure is through intermolecular forces such as hydrogen bonds and Van der Waals force, and it has a high elastic modulus, so that the thickness of the silicon-based negative electrode expands like a spring when lithium ions are intercalated and extracted. Grow and shrink, but the battery ultimately exhibits little variation in thickness expansion.
  • the mass percentage of the ethylene carbonate (FEC) to the total mass of the non-aqueous electrolytic solution is B, and the propyl propionate (PP) accounts for the non-aqueous electrolytic solution.
  • the mass percentage of the total mass of the electrolyte is C, then A, B, and C need to satisfy the following relationship: 0.01 ⁇ A/B ⁇ 10, 0.01 ⁇ A/(B+C) ⁇ 0.15.
  • the mass percentage of the ethylene carbonate (FEC) in the total mass of the non-aqueous electrolyte is B, and the range of B is 1-20wt%, for example, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt%, preferably 10wt% ⁇ 20wt%.
  • the mass percentage of the propyl propionate (PP) to the total mass of the non-aqueous electrolyte is C, and the range of C is 0-40wt% and not 0,
  • ethylene carbonate (FEC) can form a stable SEI film on the silicon-based negative electrode, thereby ensuring the cycle performance of the battery; and the amount of propyl propionate (PP) and the binding agent is within the ratio defined in the present disclosure.
  • FEC ethylene carbonate
  • PP propyl propionate
  • the bonding effect of the binder can be better, and the swelling rate of the binder is also lower, thereby greatly reducing the cyclic expansion rate of the silicon-based negative electrode, and then making the present disclosure adopt the silicon-based negative electrode material
  • the lithium-ion battery achieves excellent cycle performance and low cycle expansion while having high energy density.
  • the positive electrode active material in the positive electrode is selected from one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganate, ternary nickel-cobalt-manganese, and ternary nickel-cobalt-aluminum.
  • the positive electrode active material in the positive electrode is selected from lithium cobaltate or lithium cobaltate that has been doped and/or coated with one or more elements of Al, Mg, Ti, Zr.
  • the chemical formula of the positive electrode active material is Li b Co 1-a MaO 2 ; wherein 0.95 ⁇ b ⁇ 1.05, 0 ⁇ a ⁇ 0.1, and M is selected from one of Al, Mg, Ti, Zr elements or Various.
  • the non-aqueous electrolyte further includes electrolyte functional additives.
  • the electrolyte functional additive is selected from one or more of the following compounds: 1,3-propane sultone, 1,3-propene sultone, vinylene carbonate, fluoroethylene carbonate ester, vinyl sulfate, lithium difluorophosphate, lithium bistrifluoromethanesulfonyl imide, lithium bisfluorosulfonyl imide.
  • the non-aqueous electrolyte further includes a non-aqueous organic solvent.
  • the non-aqueous organic solvent is selected from a mixture of at least one of cyclic carbonates mixed with at least one of linear carbonates and linear carboxylates in any proportion.
  • the cyclic carbonate is selected from at least one of ethylene carbonate and propylene carbonate.
  • the linear carbonate is at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
  • the linear carboxylic acid ester is at least one selected from ethyl propionate, propyl propionate and propyl acetate.
  • the non-aqueous electrolytic solution further includes an electrolyte lithium salt.
  • the electrolyte lithium salt is at least one selected from lithium hexafluorophosphate and lithium perchlorate.
  • the concentration of electrolyte lithium salt in the non-aqueous electrolyte is 0.5mol/L-2.0mol/L, exemplarily 0.5mol/L, 1.0mol/L, 1.5mol/L, 2.0mol/L .
  • the anode is an electrode based on a silicon-based anode material and/or a carbon-based anode material, for example, the anode material is selected from artificial graphite, natural graphite, mesocarbon microspheres, hard carbon, soft carbon, One or more of nano-silicon, silicon-oxygen material, and silicon-carbon material.
  • the charging cut-off voltage of the lithium-ion battery is 4.45V or above.
  • binder refers to the binder in lithium-ion batteries, which is a polymer compound, an inactive component in lithium-ion battery electrode sheets, and must be used to prepare lithium-ion battery electrode sheets.
  • the main function of "binder” is to connect the electrode active material, conductive agent and electrode collector, so that there is an overall connection between them, thereby reducing the impedance of the electrode, and at the same time making the electrode sheet have good mechanical properties and machinability performance to meet the needs of actual production.
  • the present disclosure provides a lithium-ion battery with high energy density and excellent cycle life and low cycle expansion rate.
  • the lithium-ion battery includes a positive pole, a negative pole, a diaphragm and a non-aqueous electrolyte; wherein: Include at least fluoroethylene carbonate (FEC) and propyl propionate (PP) in the described non-aqueous electrolytic solution;
  • Described negative electrode comprises binder, and described binder is the polymer that side chain contains hydroxyl, and is Graft copolymerization of one or more of acrylic acid, acrylonitrile, acrylamide, acrylate, styrene, vinylimidazole, vinylpyridine, sodium p-styrenesulfonate, etc.
  • the binder is used on the negative electrode, which improves the compatibility between the binder and the electrolyte, thereby making the surface energy of the negative electrode Form a stable SEI interface, thereby improving the cycle performance of the battery.
  • FEC ethylene carbonate
  • PP propyl propionate
  • the present disclosure further adjusts the content A of the binder in the negative electrode slurry, the content B of ethylene carbonate (FEC) in the electrolyte, and the content C of propyl propionate (PP) in the electrolyte, so that A, B and C meet: 0.01 ⁇ A/B ⁇ 10, 0.01 ⁇ A/(B+C) ⁇ 0.15, so that a more stable SEI interface can be formed on the surface of the silicon-based negative electrode, thereby improving the cycle performance of the battery; at the same time, when the electrolyte When the content of propyl propionate (PP) and the binder satisfy a certain relationship, the cycle expansion rate of the lithium-ion battery using silicon-based negative electrode materials can also be reduced.
  • FEC ethylene carbonate
  • PP propyl propionate
  • the hydroxyl-containing polymer (such as polyvinyl alcohol, polymethylvinyl alcohol, polyhydroxyethyl acrylate, polyhydroxyethyl acrylate, etc.) used in the present disclosure has good flexibility and high tensile strength. tensile strength.
  • the adhesive disclosed in the present disclosure can be prepared by further grafting and copolymerization by using the hydroxyl group as the initiation site.
  • the binder of the present disclosure has good flexibility and cohesiveness at the same time, and the graft copolymerization of other groups such as carboxylic acid groups can further endow the binder with excellent properties such as good dispersibility.
  • Fig. 1 is the infrared spectrogram of the PVA-g-P (AA-co-AN) binding agent that makes in embodiment 1.
  • 45°C high-temperature cycle test After measuring the battery with 50% SOC after OCV, test the voltage, internal resistance, and thickness T1 of the battery first, and then place the battery in a constant temperature environment of 45°C at a rate of 0.7C/0.5C. Charge and discharge test, the cut-off voltage range is 3.0V ⁇ 4.48V, charge and discharge cycle 500 times, record the cycle discharge capacity and divide it by the discharge capacity of the first cycle to obtain the normal temperature cycle capacity retention rate; after 500 cycles, the full charge The battery was taken out of the incubator at 45°C, and the thickness T2 of the fully charged hot state after 500 cycles was measured immediately, and the capacity retention rate of the 500th cycle and the cycle thickness expansion rate of the battery cycle were recorded respectively, as shown in Table 3. Show. in:
  • Thickness expansion ratio (%) (T2-T1)/T1 ⁇ 100%.
  • the corresponding lithium-ion batteries are prepared by controlling the content of PVA-g-P(AA-co-AN) binder in the negative electrode sheet and the content of FEC and PP in the non-aqueous electrolyte.
  • the positive electrode active material lithium cobalt oxide (LCO), the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are mixed according to the weight ratio of 97:1.5:1.5, N-methylpyrrolidone (NMP) is added, and the mixture is mixed in a vacuum mixer Stir under action until the mixed system becomes a positive electrode slurry with uniform fluidity; evenly coat the positive electrode slurry on a 10 ⁇ m current collector aluminum foil, and the coating surface density is 10 mg/cm 2 ; After baking in an oven with a temperature gradient, it was dried in an oven at 120° C. for 8 hours, and then rolled and cut to obtain the desired positive electrode sheet.
  • NMP N-methylpyrrolidone
  • Binder PVA-gP (AA-co-AN) preparation Weigh 1 g of polyvinyl alcohol (PVA, molecular weight Mw: 3000, commercially available), dissolve it in 100 g of deionized water to form a solution. Then add 0.1g Na 2 S 2 O 8 /0.03g NaHSO 3 initiator into the solution and stir for 10 min to generate alkoxy radicals. Add acrylic acid monomer (AA, 4.7g) and acrylonitrile monomer (AN, 2.3g) under the protection of argon, and react at 60°C for 3h under the protection of argon. The reaction product was treated with ethanol and acetone respectively to obtain the final product PVA-gP(AA-co-AN), whose structural formula is shown in the figure below:
  • PVA-g-P (AA-co-AN) is characterized by infrared spectroscopy, and the results are shown in Figure 1. From the figure, the characteristic peaks of hydroxyl, carboxylic acid groups and nitrile groups can be seen, thus indicating that the PVA-g-P (AA-co-AN) It is disclosed that PVA-g-P(AA-co-AN) adhesive was successfully prepared.
  • Negative sheet preparation silicon-based negative electrode active material, thickener sodium carboxymethylcellulose (CMC-Na), binder PVA-gP (AA-co-AN), conductive agent acetylene black according to weight ratio 97:( 2-A): Mix A: 1, add deionized water, and obtain negative electrode slurry under the action of a vacuum mixer; evenly coat the negative electrode slurry on 6 ⁇ m high-strength carbon-coated copper foil, with an area density of 5.1 mg/cm 2 , to obtain a negative electrode sheet; the obtained electrode sheet was dried at room temperature and then transferred to an oven at 80° C. for 10 h, and then rolled and cut to obtain a negative electrode sheet.
  • CMC-Na thickener sodium carboxymethylcellulose
  • binder PVA-gP AA-co-AN
  • conductive agent acetylene black according to weight ratio 97:( 2-A): Mix A: 1, add deionized water, and obtain negative electrode slurry under the action of a vacuum
  • the average peel strength of the negative electrode sheet made of PVA-g-P (AA-co-AN) binder can reach 19.3N/m, while the average peel strength of the negative electrode sheet made of commercial SBR
  • the peel strength is only 8.4N/m
  • the average peel strength of the negative electrode sheet made of PVA is only 6.2N/m
  • the average peel strength of the negative electrode sheet made of PAA is only 5.3N/m
  • the average peel strength of the negative electrode sheet made of PAN is only 5.3N/m.
  • the average peel strength of the negative electrode sheet is only 7.1N/m.
  • the PVA-g-P(AA-co-AN) binder has good flexibility and adhesion due to the PVA component, and the acrylic acid (AA) component in the graft-copolymerized P(AA-co-AN) has good dispersion and high mechanical strength, while the acrylonitrile (AN) component has good wettability to the negative electrode active material and can form a strong ion-dipole interaction, which is conducive to improving the bonding strength of the binder.
  • the rigid and flexible structure of the adhesive prepared in the present disclosure can effectively improve the peel strength of the pole piece, thus helping to reduce the expansion rate of the silicon-based negative electrode.
  • the 8 ⁇ m thick mixed coating (5 ⁇ m+3 ⁇ m) polyethylene separator was selected.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above in order to ensure that the separator film is between the positive and negative electrode sheets to play the role of isolation, and then obtain the bare cell without liquid injection by winding; the bare cell
  • the core is placed in the outer packaging foil, and the corresponding electrolyte prepared above is injected into the dried bare cell, and the corresponding lithium-ion battery is obtained through vacuum packaging, standing, formation, shaping, and sorting.
  • Examples 1-3 and Comparative Examples 1-4 in Table 2 are benchmark battery packs, in which the content of ethylene carbonate (FEC) is fixed at 10%, the content of propyl propionate (PP) is fixed at 30%, and only PVA-g-P (AA-co-AN) binder content, with the gradual increase of PVA-g-P(AA-co-AN) binder content, A/B and A/(B+C) also showed an increase Large trend, wherein the ratio ranges of A/B and A/(B+C) in Comparative Examples 1-4 are not within the 0.01 ⁇ A/B ⁇ 10, 0.01 ⁇ A/(B+C) ⁇ 0.15 defined in this disclosure within range.
  • FEC ethylene carbonate
  • PP propyl propionate
  • Examples 4-6 and Comparative Examples 5-9 in Table 2 are benchmark battery packs, wherein the PVA-g-P (AA-co-AN) binder content is fixed at 3%, and the propyl propionate (PP) content is fixed at 30%. %, only changing the ethylene carbonate (FEC) content, with the gradual increase of ethylene carbonate (FEC) content, A/B and A/(B+C) also showed a decreasing trend.
  • the results of cycle capacity retention and thickness expansion in Table 3 show that with the gradual increase of ethylene carbonate (FEC) content, the cycle capacity retention of the battery first increases and then decreases, while the cycle thickness expansion appears first. Decrease followed by an increase trend.
  • ethylene carbonate (FEC) can establish a relatively complete and stable SEI interface on the surface of the silicon-based negative electrode, and a stable SEI interface helps to optimize the cycle performance of the battery.
  • FEC ethylene carbonate
  • the amount of ethylene carbonate (FEC) reaches an optimum
  • the cycle performance of the battery cell is optimal, and the thickness expansion growth is also within a stable and normal range.
  • Examples 7-10 and Comparative Examples 10-15 in Table 2 are benchmark battery packs, wherein the content of PVA-g-P(AA-co-AN) binder is fixed at 3%, and the content of ethylene carbonate (FEC) is fixed at 10%.
  • FEC ethylene carbonate
  • A/B is a constant value
  • A/(B+C) also shows a decreasing trend, where The ratio range of A/(B+C) in Comparative Examples 10-11 is not within the range of 0.01 ⁇ A/(B+C) ⁇ 0.15 defined in the present disclosure, and the cycle capacity retention rate of the lithium-ion batteries thus prepared is uniform.
  • the swelling of the binder in the electrolyte can reach an appropriate level, and at this time the toughness of the binder is the largest, and the silicon-based negative electrode is The thickness expansion during charging and discharging is large, and the binder at this time can act as a spring, so that the electrode sheets in the battery can be bonded well; at the same time, the appropriate content of ethylene carbonate (FEC) can also make the battery able to A stable SEI interface is formed, so that the cycle performance of the battery is better, and the cycle thickness expansion is also within the normal range.
  • FEC ethylene carbonate
  • the swelling of the adhesive is too large, which will affect the function of the adhesive. The stability is poor, which will affect the cycle capacity retention rate and cycle thickness expansion rate of the battery.
  • the lithium-ion battery of the present disclosure has high energy density while achieving excellent cycle life and low cycle thickness expansion rate, showing extremely high application value.

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Abstract

本公开公开一种锂离子电池，所述锂离子电池包括正极、负极、隔膜和非水电解液；其中：所述非水电解液中至少包括FEC和PP；所述负极包括粘结剂，所述粘结剂为侧链含有羟基的聚合物，且为羟基上接枝共聚丙烯酸、丙烯腈、丙烯酰胺、丙烯酸酯、苯乙烯、乙烯基咪唑、乙烯基吡啶、对苯乙烯磺酸钠等中的一种或几种的接枝共聚物。本公开的锂离子电池在硅基负极表面能形成稳定的SEI界面，由此制得的锂离子电池在具有高能量密度的同时兼具优异循环寿命和低循环膨胀率。

Description

一种锂离子电池 技术领域
本公开属于锂离子电池技术领域，具体涉及一种锂离子电池。
发明背景
近年来，高能量密度锂离子电池一直是科研与产业领域内的热门主题；提升锂离子电池的能量密度可以使终端产品在性能上有显著提升，如智能电子产品更高的续航能力。提高材料的克容量是提升锂离子电池能量密度的主要手段。硅(Si)基负极材料的理论比容量高达4200mAh/g，同时其嵌脱锂平台较适宜，因而是一种理想的锂离子电池用高克容量负极材料。然而在充放电过程中，Si的体积膨胀达到300％以上，剧烈的体积变化所产生的内应力，容易导致电极粉化、剥落，从而影响电池的性能和循环稳定性。
为了改善硅基负极材料的体积膨胀，除了从硅基负极本身进行材料改性外，采用柔韧性好、粘接强度大的新型粘结剂也是一种有效的手段。目前商品化的粘结剂大部分粘结刚性大、柔韧性小，因而对于硅负极的体积膨胀抑制效果不好，并且粘结剂与电解液匹配性差，且在电解液中粘接强度急剧下降。
因此，亟需开发一种粘结剂与电解液匹配性好，硅基负极的循环膨胀率低且循环保持率高的锂离子电池。
发明内容
为了改善现有技术的不足，本公开提供一种锂离子电池，所述锂离子电池通过提升粘结剂与电解液的匹配性，使电池具有高能量密度的同时兼具优异循环寿命和低循环膨胀率。
本公开是通过如下技术方案实现的：
一种锂离子电池，所述锂离子电池包括正极、负极、隔膜和非水电解液；其中：
所述非水电解液中至少包括氟代碳酸乙烯酯(FEC)和丙酸丙酯(PP)；
所述负极包括粘结剂，所述粘结剂为侧链含有羟基的聚合物，且为羟基上接枝共聚丙烯酸、丙烯腈、丙烯酰胺、丙烯酸酯、苯乙烯、乙烯基咪唑、乙烯基吡啶、对苯乙烯磺酸钠等中的一种或多种的接枝共聚物。
根据一种具体的实施方案，所述粘结剂具有如式1或式2所示的结构：
Figure PCTCN2022130417-appb-000001
其中：
R 1、R 3、R 4、R 5、R 7、R 8相同或不同，彼此独立地选自H、C 1-6烷基，优选H、C 1-4烷基，例如H、甲基、乙基、丙基；
R 2、R 6相同或不同，彼此独立地选自羧酸基、酰胺基、酯基、磺酸基、苯基、咪唑基、腈基等基团及相关基团衍生基团中的一种或多种组合；
x为1～100万、y为10～100万、z为1～100万；
a为1～100万、b为10～100万、c为1～2000、d为10～100万、e为0～2000。
在一实例中，所述负极包括负极活性层，所述负极活性层中包括所述粘结剂，所述粘结剂的重量在负极活性层中的占比为A，A的范围是1wt％～30wt％，例如为1wt％、2wt％、3wt％、5wt％、8wt％、10wt％、15wt％、20wt％、25wt％、30wt％，优选为3wt％～30wt％。
本公开负极中的粘接剂主要作用是通过氢键、范德华力等分子间作用力，且其具有高的弹性模量，使得硅基负极在锂离子嵌入和脱出时的厚度膨胀如弹簧式的增大和缩小，但电池最终表现出来的厚度膨胀变化不大。
在一实例中，所述非水电解液中，所述碳酸乙烯酯(FEC)占所述非水电解液总质量的质量百分比为B，所述丙酸丙酯(PP)占所述非水电解液总质量的质量百分比为C，则A、B、C需满足以下关系：0.01≤A/B≤10，0.01≤A/(B+C)≤0.15。
在一实例中，所述非水电解液中，所述碳酸乙烯酯(FEC)占所述非水电 解液总质量的质量百分比为B，B的范围是1～20wt％，例如为1wt％、2wt％、5wt％、8wt％、10wt％、15wt％、20wt％，优选为10wt％～20wt％。
在一实例中，所述非水电解液中，所述丙酸丙酯(PP)占所述非水电解液总质量的质量百分比为C，C的范围是0～40wt％且不为0，例如为0.1wt％、2wt％、5wt％、8wt％、10wt％、15wt％、20wt％、25wt％、30wt％、35wt％、40wt％，优选为10wt％～40wt％。
本公开中，碳酸乙烯酯(FEC)能在硅基负极上形成稳定的SEI膜，从而能够保证电池的循环性能；而丙酸丙酯(PP)与粘结剂的用量在本公开限定的比例范围内时，能够使粘结剂的粘结效果更佳，且使粘接剂的溶胀率也较低，从而能够大大的降低硅基负极的循环膨胀率，进而使本公开采用硅基负极材料的锂离子电池在具备高能量密度的同时实现优异的循环性能及低的循环膨胀率。
在一实例中，所述正极中的正极活性材料选自过渡金属锂氧化物、磷酸铁锂、锰酸锂、三元镍钴锰、三元镍钴铝中的一种或多种。
在一实例中，所述正极中的正极活性材料选自钴酸锂或经过Al、Mg、Ti、Zr中一种或多种元素掺杂和/或包覆处理的钴酸锂。示例性地，所述正极活性材料的化学式为Li bCo 1-aMaO 2；其中0.95≤b≤1.05，0≤a≤0.1，M选自Al、Mg、Ti、Zr元素中的一种或多种。
在一实例中，所述非水电解液中还包含电解液功能添加剂。优选地，所述电解液功能添加剂选自如下化合物中的一种或多种：1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、碳酸亚乙烯酯、氟代碳酸乙烯酯、硫酸乙烯酯、二氟磷酸锂、双三氟甲烷磺酰亚胺锂、双氟磺酰亚胺锂。
在一实例中，所述非水电解液中还包含非水有机溶剂。优选地，所述非水有机溶剂选自环状碳酸酯中的至少一种与线性碳酸酯和线性羧酸酯两者中的至少一种按任意比例混合的混合物。
示例性地，所述环状碳酸酯选自碳酸乙烯酯和碳酸丙烯酯中的至少一种。
示例性地，所述线性碳酸酯选自碳酸二甲酯、碳酸二乙酯和碳酸甲乙酯中的至少一种。
示例性地，所述线性羧酸酯选自丙酸乙酯、丙酸丙酯和乙酸丙酯中的至少一种。
在一实例中，所述非水电解液中还包含电解质锂盐。优选地，所述电解质锂盐选自六氟磷酸锂和高氯酸锂中的至少一种。
在一实例中，所述非水电解液中电解质锂盐的浓度为0.5mol/L～2.0mol/L，示例性为0.5mol/L、1.0mol/L、1.5mol/L、2.0mol/L。
在一实例中，所述负极为基于硅基负极材料和/或碳基负极材料的电极，例如，所述负极材料选自人造石墨、天然石墨、中间相碳微球、硬碳、软碳、纳米硅、硅氧材料、硅碳材料中的一种或多种。
在一实例中，所述锂离子电池的充电截止电压为4.45V及以上。
术语与解释：
本公开中，术语“粘结剂”是指锂离子电池中的粘结剂，是一种高分子化合物，是锂离子电池电极片中的非活性成分，是制备锂离子电池电极片必须使用的重要材料之一。“粘结剂”的主要作用是连接电极活性物质、导电剂和电极集流体，使它们之间具有整体的连接性，从而减小电极的阻抗，同时使电极片具有良好的机械性能和可加工性能，满足实际生产的需要。
本公开的有益效果：
(1)本公开提供一种具有高能量密度的同时兼具优异循环寿命及较低循环膨胀率的的锂离子电池，所述锂离子电池包括正极、负极、隔膜和非水电解液；其中：所述非水电解液中至少包括氟代碳酸乙烯酯(FEC)和丙酸丙酯(PP)；所述负极包括粘结剂，所述粘结剂为侧链含有羟基的聚合物，且为羟基上接枝共聚丙烯酸、丙烯腈、丙烯酰胺、丙烯酸酯、苯乙烯、乙烯基咪唑、乙烯基吡啶、对苯乙烯磺酸钠等中的一种或几种的接枝共聚物。通过在非水电解液中引入碳酸乙烯酯(FEC)和丙酸丙酯(PP)，在负极上使用所述粘结剂，提高了粘结剂与电解液的匹配性，从而使负极表面能形成稳定的SEI界面，从而提升电池的循环性能。
(2)本公开进一步通过调整粘结剂在负极浆料中的含量A、电解液中碳酸乙烯酯(FEC)的含量B和电解液中丙酸丙酯(PP)的含量C，使A、B、C满足：0.01≤A/B≤10，0.01≤A/(B+C)≤0.15，从而使硅基负极表面能形成更稳定的SEI界面，从而提升电池的循环性能；同时当电解液中丙酸丙酯(PP)与粘结剂含量满足一定的关系时，还能使采用硅基负极材料的锂离子电池的循环膨胀率较小。
(3)本公开使用的含有羟基的聚合物(如聚乙烯醇、聚甲基乙烯醇，聚羟乙基丙烯酸酯，聚羟乙基丙烯酸甲酯等)柔韧性好，并具有较高的拉伸强度。本公开的粘接剂可利用羟基作为引发位点，进一步接枝共聚制备得到。本公开的粘结剂同时具有良好的柔韧性和粘结性，同时接枝共聚其他基团如羧酸基团等，还可进一步赋予粘结剂良好地分散性等优异性能。
附图简要说明
图1为实施例1中制得的PVA-g-P(AA-co-AN)粘结剂的红外谱图。
实施本发明的方式
下文将结合具体实施例对本公开做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本公开，而不应被解释为对本公开保护范围的限制。凡是对本公开技术方案进行修正或等同替换，而不脱离本公开技术方案的精神范围，均应涵盖在本公开的保护范围之中。
下述制备得到的锂离子电池循环寿命测试：
45℃高温循环测试：将测完OCV后50％SOC的电池，来料时先测试电池的电压、内阻、厚度T1，然后将电池置于45℃恒温环境下以0.7C/0.5C倍率进行充放电测试，截止电压范围为3.0V～4.48V，充放循环500次，记录循环放电容量并除以第一次循环的放电容量，得到常温循环容量保持率；循环500周结束后将满电电池从45℃恒温箱中取出，立即测试其循环500周后热态满电的厚度T2，分别记录第500次循环容量保持率和电池循环500周次时的循环厚度膨胀率，如表3所示。其中：
厚度膨胀率(％)＝(T2-T1)/T1×100％。
对比例1～15以及实施例1～10
在锂离子电池的制造过程中，通过控制负极片中PVA-g-P(AA-co-AN)粘结剂的含量、非水电解液中FEC及PP含量，制备得到相应的锂离子电池。
所有对比例1～15和实施例1～10的锂离子电池在制备过程中除了以上提及的不同因素外，其余所有制备过程均一致，并如下所述：
(1)正极片制备
将正极活性材料钴酸锂(LCO)、粘结剂聚偏氟乙烯(PVDF)、导电剂乙炔黑按照重量比97:1.5:1.5进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌，直至混合体系成均一流动性的正极浆料；将正极浆料均匀涂覆在10μm集流体铝箔上，涂覆面密度为10mg/cm 2；将上述涂覆好的铝箔在5段不同温度梯度的烘箱烘烤后，再将其在120℃的烘箱干燥8h，然后经过辊压、分切得到所需的正极片。
(2)负极片制备
粘结剂PVA-g-P(AA-co-AN)制备：称取1g聚乙烯醇(PVA，分子量Mw:3000，商品化)，溶于100g去离子水中配置成溶液。然后将0.1g Na 2S 2O 8/0.03g NaHSO 3引发剂加入到溶液中搅拌10min，产生烷氧基自由基。在氩气保护下加入丙烯酸单体(AA，4.7g)和丙烯腈单体(AN，2.3g)，并在氩气保护下60℃反应3h。反应产物分别用乙醇和丙酮处理，得到最终产物PVA-g-P(AA-co-AN)，其结构式如下图所示：
Figure PCTCN2022130417-appb-000002
通过红外谱图对PVA-g-P(AA-co-AN)的结构进行表征，结果如图1所示，从图中可以看到羟基、羧酸基团和腈基的特征峰，由此表明本公开成功制备了PVA-g-P(AA-co-AN)粘接剂。
负极片制备：将硅基负极活性材料、增稠剂羧甲基纤维素钠(CMC-Na)、粘结剂PVA-g-P(AA-co-AN)、导电剂乙炔黑按照重量比97:(2-A):A:1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料；将负极浆料均匀涂覆在6μm高强度涂炭铜箔上，面密度为5.1mg/cm 2，得到负极片；将所得极片在室温晾干后转移至80℃烘箱干燥10h，然后经过辊压、分切得到负极片。
作为对比：分别采用均聚的聚乙烯醇(PVA，Mw:45万)、聚丙烯酸(PAA，Mw:45万)和聚丙烯腈(PAN，Mw:40万)以及丁苯橡胶乳液(SBR，型号451B)作为粘结剂，利用相同的配比和工艺制备负极极片，并对辊压后极片做剥离强度的测试，结果如表1所示。
表1 使用不同粘结剂制得的负极片的剥离强度
粘结剂类型 平均剥离强度(N/m)
PVA 6.2
PAA 5.3
PAN 7.1
SBR 8.4
PVA-g-P(AA-co-AN) 19.3
从表1中可以看出：使用PVA-g-P(AA-co-AN)粘结剂制得的负极片的平均剥离强度可以达到19.3N/m，而由商品化SBR制得的负极片的平均剥离强度仅为8.4N/m，由PVA制得的负极片的平均剥离强度仅为6.2N/m，由PAA制得的负极片的平均剥离强度仅为5.3N/m，由PAN制得的负极片的平均剥离强度仅为7.1N/m。PVA-g-P(AA-co-AN)粘结剂由于PVA组分柔韧性好，粘结性好，而接枝共聚的P(AA-co-AN)中丙烯酸(AA)组分具有良好的分散性和高的机械 强度，而丙烯腈(AN)组分对负极活性物质浸润性好且可形成较强的离子-偶极相互作用，因而有利于改善粘接剂的粘接强度。本公开制得的粘接剂刚柔并济的结构有效提高了极片的剥离强度，因而有利于降低硅基负极膨胀率。
(3)电解液制备
在充满惰性气体(氩气)的手套箱中(H 2O＜0.1ppm，O 2＜0.1ppm)，将碳酸乙烯酯(EC)、碳酸丙烯酯、碳酸二乙酯、丙酸丙酯(PP)，按照3:3:2:2的质量比，混合均匀，然后往其中快速加入1.25mol/L的充分干燥的六氟磷酸锂(LiPF 6)，溶解于非水有机溶剂中，搅拌均匀，经过水分和游离酸检测合格后，得到基础电解液。
(4)隔离膜的制备
选用8μm厚的混合涂层(5μm+3μm)聚乙烯隔膜。
(5)锂离子电池的制备
将上述准备的正极片、隔离膜、负极片按顺序叠放好，保证隔离膜处于正、负极片之间起到隔离的作用，然后通过卷绕得到未注液的裸电芯；将裸电芯置于外包装箔中，将上述制备好的相应的电解液注入到干燥后的裸电芯中，经过真空封装、静置、化成、整形、分选等工序，获得相应的锂离子电池。
表2 实施例1-10及对比例1-15中PVA-g-P(AA-co-AN)粘结剂的含量、电解液中FEC及PP含量
Figure PCTCN2022130417-appb-000003
Figure PCTCN2022130417-appb-000004
表3 实施例1-10及对比例1-15的锂离子电池的循环寿命测试结果
Figure PCTCN2022130417-appb-000005
/表示在对其进行电池循环保持率和厚度膨胀率测试时，电池无法完成300周和/或500周测试。
表2中实施例1-3及对比例1-4为基准组电池，其中碳酸乙烯酯(FEC)含量固定为10％，丙酸丙酯(PP)含量固定为30％，仅改变PVA-g-P(AA-co-AN)粘结剂的含量时，随着PVA-g-P(AA-co-AN)粘结剂含量的逐步增大，A/B及A/(B+C)也呈现了增大的趋势，其中对比例1-4中A/B和A/(B+C)的比值范围均不在本公开限定的0.01≤A/B≤10，0.01≤A/(B+C)≤0.15范围内。表3循环容量保持率及厚度膨胀结果显示：随着PVA-g-P(AA-co-AN)粘结剂含量的逐步增加，电池的循环容量保持率及循环厚度膨胀均呈现先增大后减小的趋势，这是由于粘结剂的用量在合适的使用范围内，能够使负极片具有良好的粘结性能，进而使制得的锂离子电池的性能较优，同时使锂离子电池的循环厚度膨胀也在正常范围内；而一旦粘结剂的用量超出本公开限定的用量范围，则由于电 池阻抗的增大，会使负极片表面的副反应也相应增加，从而使锂离子电池的性能劣化，循环厚度膨胀也会有增大。
表2中实施例4-6及对比例5-9为基准组电池，其中PVA-g-P(AA-co-AN)粘结剂含量固定为3％，丙酸丙酯(PP)含量固定为30％，仅改变碳酸乙烯酯(FEC)含量，随着碳酸乙烯酯(FEC)含量的逐步增大，A/B及A/(B+C)也呈现了减小的趋势。表3中循环容量保持率及厚度膨胀结果显示，随着碳酸乙烯酯(FEC)含量的逐步增加，电池的循环容量保持率呈现先增大后减小的趋势，而循环厚度膨胀则出现了先减小后增大的趋势。这是由于碳酸乙烯酯(FEC)能在硅基负极表面建立起较完整及稳定的SEI界面，稳定的SEI界面有助于优化电池的循环性能，当碳酸乙烯酯(FEC)的用量达到一个最优值时，电芯的循环性能最优，厚度膨胀增长也在一个稳定正常的范围内。而当碳酸乙烯酯(FEC)的加入量小于最优值时，SEI界面构造不完整，界面的副反应增多，因而会消耗大量的电解液，并使溶剂容易在极片表面被还原，电池可能出现胀气问题，进而使电池的循环容量保持率低，循环厚度膨胀大。而当碳酸乙烯酯(FEC)的加入量大于最优值时，极片表面的SEI膜成膜过厚，会致使电池阻抗增大，进而使锂离子的传输速率受阻，因而可能导致电池循环后期出现析锂现象，从而影响电池的循环性能，增大电池的循环厚度膨胀。
表2中实施例7-10及对比例10-15为基准组电池，其中PVA-g-P(AA-co-AN)粘结剂含量固定为3％，碳酸乙烯酯(FEC)含量固定为10％，仅改变丙酸丙酯(PP)含量，随着丙酸丙酯(PP)含量的逐步增大，A/B是定值，A/(B+C)也呈现了减小的趋势，其中对比例10-11中A/(B+C)的比值范围均不在本公开限定的0.01≤A/(B+C)≤0.15范围内，由此制得的锂离子电池的循环容量保持率均较其他锂离子电池的要低，其循环厚度膨胀也比其他锂离子电池的要大。从表3循环容量保持率及厚度膨胀结果显示，随着PP含量的逐步增加，电池的循环容量保持率及循环厚度膨胀呈现先增大后减小的趋势，这是由于丙酸丙酯(PP)在极片中会起到一个加强极片浸润的效果，同时粘结剂跟丙酸丙酯(PP)也会产生相互作用。当丙酸丙酯(PP)用量过少时，粘结剂在电解液中的溶胀率、韧性均较小无法发挥其效果，因而会使硅基负极在充放电过程中的厚度膨胀较大。而当丙酸丙酯(PP)含量在本公开限定的用量范围内时，可使粘结剂在电解液中的溶胀达到合适的程度，且此时粘结剂的韧性最大，硅基负极在充放电过程中的厚度膨胀大，此时的粘结剂能够起到一个弹簧的作用，进而使电池中极片的粘结良好；同时，合适的碳酸乙烯酯(FEC)含量还可以使电池能够形成稳定的SEI界面，进而使电池的循环性能较优，循环厚度膨胀也在正常范围内。但当丙酸丙酯(PP)含量过大时，粘 结剂的溶胀过大，反而会影响粘接剂的作用，同时，高含量的丙酸丙酯(PP)在高温、高电压下的稳定性较差，因而会影响电池的循环容量保持率及循环厚度膨胀率。
综上可以看出，本公开的锂离子电池具备高能量密度的同时实现优异的循环寿命及较低的循环厚度膨胀率，表现出了极高的应用价值。
以上，对本公开的实施方式进行了说明。但是，本公开不限定于上述实施方式。凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (14)

  1. 一种锂离子电池，所述锂离子电池包括正极、负极、隔膜和非水电解液；其中：
    所述非水电解液中至少包括氟代碳酸乙烯酯和丙酸丙酯；
    所述负极包括粘结剂，所述粘结剂为侧链含有羟基的聚合物，且为羟基上接枝共聚丙烯酸、丙烯腈、丙烯酰胺、丙烯酸酯、苯乙烯、乙烯基咪唑、乙烯基吡啶、对苯乙烯磺酸钠中的一种或多种的接枝共聚物。
  2. 根据权利要求1所述的锂离子电池，其特征在于，所述粘结剂具有如式1或式2所示的结构：
    Figure PCTCN2022130417-appb-100001
    其中：
    R 1、R 3、R 4、R 5、R 7、R 8相同或不同，彼此独立地选自H、C 1-6烷基；
    R 2、R 6相同或不同，彼此独立地选自羧酸基、酰胺基、酯基、磺酸基、苯基、咪唑基、腈基基团及相关基团衍生基团中的一种或多种组合；
    x为1～100万、y为10～100万、z为1～100万；
    a为1～100万、b为10～100万、c为1～2000、d为10～100万、e为0～2000。
  3. 根据权利要求1或2所述的锂离子电池，其特征在于，所述负极包括负极活性层，所述负极活性层中包括所述粘结剂，所述粘结剂的重量在负极活性层中的占比为A，A的范围是1wt％～30wt％。
  4. 根据权利要求1-3任一项所述的锂离子电池，其特征在于，所述非水电解液中，所述碳酸乙烯酯占所述非水电解液总质量的质量百分比为B，所述丙酸丙酯占所述非水电解液总质量的质量百分比为C，则A、B、C需满足以下关系：0.01≤A/B≤10，0.01≤A/(B+C)≤0.15。
  5. 根据权利要求1-4任一项所述的锂离子电池，其特征在于，所述非水电解液中，所述碳酸乙烯酯占所述非水电解液总质量的质量百分比为B，B的范围是1～20wt％。
  6. 根据权利要求1-5任一项所述的锂离子电池，其特征在于，所述非水电解液中，所述丙酸丙酯占所述非水电解液总质量的质量百分比为C，C的范围是0～40wt％且不为0。
  7. 根据权利要求1-6任一项所述的锂离子电池，其特征在于，所述正极中的正极活性材料选自过渡金属锂氧化物、磷酸铁锂、锰酸锂、三元镍钴锰、三元镍钴铝中的一种或多种；
    优选地，所述正极中的正极活性材料选自钴酸锂或经过Al、Mg、Ti、Zr中一种或多种元素掺杂和/或包覆处理的钴酸锂。
  8. 根据权利要求1-7任一项所述的锂离子电池，其特征在于，所述非水电解液中还包含电解液功能添加剂；
    优选地，所述电解液功能添加剂选自如下化合物中的一种或多种：1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、碳酸亚乙烯酯、氟代碳酸乙烯酯、硫酸乙烯酯、二氟磷酸锂、双三氟甲烷磺酰亚胺锂、双氟磺酰亚胺锂。
  9. 根据权利要求1-8任一项所述的锂离子电池，其特征在于，所述非水电解液中还包含非水有机溶剂；
    优选地，所述非水有机溶剂选自环状碳酸酯中的至少一种与线性碳酸酯和线性羧酸酯两者中的至少一种按任意比例混合的混合物。
  10. 根据权利要求9所述的锂离子电池，其特征在于，所述环状碳酸酯选自碳酸乙烯酯和碳酸丙烯酯中的至少一种；
    优选地，所述线性碳酸酯选自碳酸二甲酯、碳酸二乙酯和碳酸甲乙酯中的至少一种；
    优选地，所述线性羧酸酯选自丙酸乙酯、丙酸丙酯和乙酸丙酯中的至少一种。
  11. 根据权利要求1-10任一项所述的锂离子电池，其特征在于，所述非水电解液中还包含电解质锂盐；
    优选地，所述电解质锂盐选自六氟磷酸锂和高氯酸锂中的至少一种。
  12. 根据权利要求1-11任一项所述的锂离子电池，其特征在于，所述非水电解液中电解质锂盐的浓度为0.5mol/L～2.0mol/L。
  13. 根据权利要求1-12任一项所述的锂离子电池，其特征在于，所述负极为 基于硅基负极材料和/或碳基负极材料的电极；
    优选地，所述负极材料选自人造石墨、天然石墨、中间相碳微球、硬碳、软碳、纳米硅、硅氧材料、硅碳材料中的一种或多种。
  14. 根据权利要求1-13任一项所述的锂离子电池，其特征在于，所述锂离子电池的充电截止电压为4.45V及以上。
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