A lithium-ion battery

Abstract

In order to overcome the problems of rate, cycle and capacity reduction of the lithium ion battery electrolyte in the prior art, the application provides a lithium ion battery, which comprises a positive electrode, a negative electrode and an electrolyte, the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material and a lithium supplement additive, the electrolyte comprises a solvent, a lithium salt and a lithium sulfonate compound, the solvent comprises a fluorinated solvent, the structure of the fluorinated solvent is as shown in the following formula: wherein Z1 and Z2 are selected from fluorinated hydrocarbon groups with 1-5 carbon atoms; the structure general formula of the lithium sulfonate compound is as shown in the following formula: wherein R is selected from hydrocarbon groups with 1-4 carbon atoms. In the lithium ion battery provided by the application, the lithium sulfonate compound, the lithium supplement additive and the fluorinated solvent are used simultaneously, which can have a synergistic effect, and can effectively improve the initial efficiency of the battery, the high-temperature cycle performance of the battery, the high-temperature storage performance of the battery and the initial efficiency of the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and specifically relates to a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are widely used in consumer electronics and power batteries due to their advantages such as high specific energy, fast charging and discharging capabilities, and low self-discharge. As the operating conditions of electronic products and power batteries become increasingly complex, the requirements for lithium-ion batteries are also increasing, especially regarding battery capacity and lifespan.

[0003] The performance of lithium-ion batteries is influenced by a combination of factors, among which energy density and cycle performance are two particularly critical indicators. The electrolyte, as one of the core materials of a lithium battery, acts as a combustion medium, transporting ions and conducting current between the positive and negative electrodes. Choosing a suitable electrolyte is crucial for obtaining lithium batteries with high energy density, long cycle life, and good safety performance. Lithium-replenishing additives are typically added to the electrolyte; however, these additives become structurally unstable after delithiation, affecting electrolyte quality and easily undergoing side reactions with the electrolyte at high potentials, leading to increased electrode interface impedance and reduced battery rate capability, cycle performance, and capacity. Summary of the Invention

[0004] To address the issues of reduced battery rate, cycle life, and capacity caused by electrolytes in existing lithium-ion batteries, a lithium-ion battery is provided.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] This invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode active material layer, which comprises a positive electrode active material and a lithium-replenishing additive. The electrolyte comprises a solvent, a lithium salt, and a lithium sulfonate compound. The solvent includes a fluorinated solvent, the structure of which is shown below:

[0007]

[0008] Z1 and Z2 are selected from fluoroalkyl groups with 1 to 5 carbon atoms;

[0009] The general structural formula of the lithium sulfonate compounds is shown below:

[0010]

[0011] Where R is selected from hydrocarbon groups with 1-4 carbon atoms;

[0012] The lithium supplement additive is selected from Li x M y O z, where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M is one or more of Ni, Co, Fe, Cu, Al, Mn, Ti, P, Si, and C.

[0013] Optionally, the fluorinated solvent includes one or more of the following compounds:

[0014]

[0015] The content of fluorinated solvents accounts for 3 to 15 wt% of the total solvent mass.

[0016] Optionally, the lithium sulfonate compound includes one or more of the following compounds:

[0017] Lithium methyl isocyanate sulfonate, lithium ethyl isocyanate sulfonate, lithium isopropyl cyanate sulfonate.

[0018] Optionally, the lithium supplementation additive includes one or more of the following compounds:

[0019] Li2NiO2, Li5FeO4, Li2O, Li2MnO3, Li6CoO4, Li6MnO4, Li5ReO6.

[0020] Optionally, based on the total mass of the electrolyte (100%), the lithium sulfonate compound has a mass percentage content of 0.01–10%, and the fluorinated solvent has a mass percentage content of 3–15%.

[0021] Optionally, the mass percentage of the lithium supplementation additive is 0.01 to 10% based on the total mass of the positive electrode (100%).

[0022] Optionally, the electrolyte may also include a film-forming additive, wherein the film-forming additive comprises 3 to 15% by mass, based on the total mass of the electrolyte (100%).

[0023] Optionally, the film-forming additive is one or more of vinylene carbonate and its derivatives, halogen-substituted cyclic carbonates, chelated orthoborates, and chelated orthophosphates.

[0024] Optionally, the lithium salt is selected from one or more organic electrolyte salts and inorganic electrolyte salts, including LiPF6, LiBF4, LiSbF6, LiAsF6, LiTaF6, LiAlCl4, and Li2B. 10 Cl 10 Li2B 10 F 10One or more of the following: LiClO4, LiCF3SO3, LiB(C2O4)2, LiB(O2CCH2CO2)2, LiB(O2CCF2CO2)2, LiB(C2O4)(O2CCH2CO2), LiB(C2O4)(O2CCF2CO2), LiP(C2O4)3, and LiP(O2CCF2CO2)3.

[0025] Optionally, the positive electrode active material accounts for 80-99% of the mass of the positive electrode active material layer, and the positive electrode active material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and LiNi. x Co y Mn z One or more of O2(x+y+z=1,x≥y).

[0026] The lithium-ion battery provided by this invention provides a lithium source during the first charge after adding a lithium replenishment additive, compensating for the lithium consumed by the SEI film. As the amount of lithium replenishment additive increases, the battery's initial efficiency increases. However, the lithium replenishment additive becomes structurally unstable after delithiation and is prone to side reactions with the electrolyte at high potentials, leading to increased electrode interface impedance and deteriorating the battery's rate performance. Since the lithium sulfonate compounds have excellent film-forming properties, promoting the formation of a highly conductive and mechanically strong SEI film on the negative electrode, this effectively mitigates the side reactions such as increased electrode interface impedance caused by the lithium replenishment additive. This invention improves both the rate performance and cycle performance of the battery. The fluorine atoms in the fluorinated organic solvent have strong electronegativity and weak polarity, giving the fluorinated solvent high oxidation resistance. Therefore, when used in conjunction with lithium supplementation additives, it can effectively improve the high voltage and oxidation resistance, playing a synergistic role. On the one hand, it improves the battery's initial efficiency and cycle performance; on the other hand, it improves the thermal stability and oxidation resistance of the electrolyte solvent. The combined use of the lithium sulfonate compound, lithium supplementation additive, and fluorinated solvent synergistically improves the battery's high-temperature cycle performance, high-temperature storage performance, and initial efficiency. Detailed Implementation

[0027] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] An embodiment of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode active material layer, which comprises a positive electrode active material and a lithium-replenishing additive. The electrolyte comprises a solvent, a lithium salt, and a lithium sulfonate compound. The solvent includes a fluorinated solvent, the structure of which is shown below:

[0029]

[0030] Z1 and Z2 are selected from fluoroalkyl groups with 1 to 5 carbon atoms;

[0031] The general structural formula of the lithium sulfonate compounds is shown below:

[0032]

[0033] Where R is selected from hydrocarbon groups with 1-4 carbon atoms;

[0034] The lithium supplement additive is selected from Li x M y O z , where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M is one or more of Ni, Co, Fe, Cu, Al, Mn, Ti, P, Si, and C.

[0035] The lithium sulfonate compound is lithium methyl isocyanate sulfonate. The isocyanate group in the lithium methyl isocyanate sulfonate can react with trace amounts of water in the electrolyte and hydrogen on the surface of the positive and negative electrodes of the battery, reducing the decomposition of lithium hexafluorophosphate (LiPF6) caused by active hydrogen. This avoids the decomposition and breakage of the SEI film caused by hydrogen fluoride from the decomposition of LiPF6. In addition, the lithium sulfonate group and the isocyanate group work together to form a more flexible and conductive SEI film on the surface of the negative electrode, while avoiding the erosion of the SEI film by acidic byproducts of the electrolyte. This effectively ensures the continuity and stability of the negative electrode SEI film, and jointly improves the cycle performance and rate performance of the battery.

[0036] In some embodiments, the solvent further includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate, and tetrahydrofuran.

[0037] In some embodiments, the fluorinated solvent comprises one or more of the following compounds:

[0038]

[0039] The content of fluorinated solvents accounts for 3 to 15 wt% of the total solvent mass.

[0040] The fluorinated solvent is 2,2-difluoroethyl acetate. The fluorine atoms in the fluorinated organic solvent have strong electronegativity and weak polarity, which gives the fluorinated solvent high antioxidant capacity.

[0041] In some embodiments, the lithium sulfonate compound includes one or more of the following compounds:

[0042] Lithium methyl isocyanate sulfonate, lithium ethyl isocyanate sulfonate, lithium isopropyl cyanate sulfonate.

[0043] In some embodiments, the lithium supplementation additive includes one or more of the following compounds:

[0044] Li2NiO2, Li5FeO4, Li2O, Li2MnO3, Li6CoO4, Li6MnO4, Li5ReO6.

[0045] In some embodiments, based on the total mass of the electrolyte, the lithium sulfonate compound has a mass percentage content of 0.01 to 10%, and the fluorinated solvent has a mass percentage content of 3 to 15%.

[0046] Specifically, the lithium sulfonate compound preferably has a mass percentage content of 0.05% to 5% in the electrolyte, and the mass percentage content of the lithium sulfonate compound can be 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%; the mass percentage content of the fluorinated solvent can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0047] In some embodiments, the lithium supplementation additive has a mass percentage content of 0.01 to 10%.

[0048] The mass percentage of the lithium supplement additive can be 0.01%, 0.05%, 0.08%, 0.1%, 0.13%, 0.17%, 2%, 2.6%, 3%, 3.4%, 4%, 4.7%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0049] In some embodiments, a film-forming additive is further included, wherein the mass percentage of the film-forming additive is 3 to 15% based on the total mass of the electrolyte (100%).

[0050] In some embodiments, the film-forming additive is one or more of vinylene carbonate and its derivatives, halogen-substituted cyclic carbonates, chelated orthoborates, and chelated orthophosphates.

[0051] Specifically, the film-forming additive includes one or more of vinylene carbonate, ethylene ethylene carbonate, methylene carbonate, fluoroethylene carbonate, trifluoromethyl ethylene carbonate, and difluoroethylene carbonate.

[0052] In some embodiments, the lithium salt is selected from one or more organic electrolyte salts and inorganic electrolyte salts, including LiPF6, LiBF4, LiSbF6, LiAsF6, LiTaF6, LiAlCl4, and Li2B. 10 Cl 10 Li2B 10 F 10 One or more of the following: LiClO4, LiCF3SO3, LiB(C2O4)2, LiB(O2CCH2CO2)2, LiB(O2CCF2CO2)2, LiB(C2O4)(O2CCH2CO2), LiB(C2O4)(O2CCF2CO2), LiP(C2O4)3, and LiP(O2CCF2CO2)3.

[0053] Specifically, in some other embodiments, the lithium salt also includes one or more of hexafluorophosphate, hexafluoroarsenate, perchlorate, lithium trifluorosulfonyl, lithium difluoro(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium tri(trifluoromethylsulfonyl)methyl.

[0054] When the lithium salt concentration is too low, the electrolyte conductivity is low, which will affect the rate and cycle performance of the entire battery system; when the lithium salt concentration is too high, the electrolyte viscosity is too high, which is also not conducive to improving the rate of the entire battery system. In a more preferred embodiment, the lithium salt concentration is 0.9M to 1.3M.

[0055] In some embodiments, the positive electrode active material accounts for 80-99% of the mass ratio of the positive electrode active material layer, and the positive electrode active material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and LiNi. x Co y Mn z One or more of O2(x+y+z=1,x≥y).

[0056] In some embodiments, the negative electrode includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes one or more of natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn, Li-Sn-O, Sn, SnO, SnO2, TiO2-Li4Ti5O12 and Li-Al.

[0057] The present invention will be further illustrated by the following examples.

[0058] Example 1

[0059] This embodiment illustrates a lithium-ion battery disclosed in this invention, including the following operating steps:

[0060] Preparation of electrolyte: Ethyl carbonate (EC), diethyl carbonate (DEC), and propylene carbonate (PC) were mixed in a mass ratio of EC:DEC:PC = 1:1:1. Then, 1% lithium sulfonate compound and 5% fluorinated solvent were added and mixed evenly. Finally, LiPF6 was added to obtain an electrolyte with a LiPF6 concentration of 1.1 mol / L.

[0061] Preparation of positive electrode sheet: Lithium cobalt oxide (LiCoO2), carbon nanotubes (CNT), polyvinylidene fluoride (PVDF) binder, and lithium supplementation additive are mixed in a mass ratio of LiCoO2:CNT:PVDF:Li2NiO2 = 95:1.5:1.5:2, with the lithium supplementation additive added at 1%. The mixture is stirred thoroughly in N-methylpyrrolidone solvent to form a positive electrode slurry. This slurry is coated onto the aluminum foil of the positive electrode current collector, dried, and cold-pressed to obtain the positive electrode sheet.

[0062] Preparation of negative electrode sheet: The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber and thickener sodium carboxymethyl cellulose are mixed in an appropriate amount of deionized water solvent at a mass ratio of 96:1.2:1.5:1.3 to form a uniform negative electrode slurry. This slurry is coated on the negative electrode current collector copper foil, dried and cold pressed to obtain the negative electrode sheet.

[0063] Preparation of lithium-ion batteries: The positive electrode, separator (PE porous polymer film) and negative electrode are stacked in sequence, with the separator in the middle of the positive and negative electrodes. The stacked electrode and separator are then wound to obtain a core. The core is placed in a punched aluminum-plastic film bag. The electrolyte prepared above is injected into the baked and dried core. Vacuum sealing, standing, and formation processes are performed to obtain a lithium-ion battery.

[0064] Examples 2-4

[0065] Examples 2-4 illustrate a lithium-ion battery disclosed in this invention, including most of the operating steps in Example 1, with the following differences:

[0066] Examples 2-4 used the amounts of lithium-supplementing additives, lithium sulfonate compounds, and fluorinated solvents shown in Table 1 for Examples 2-4.

[0067] Comparative Examples 1-7

[0068] Comparative Examples 1-7 are used to illustrate a lithium-ion battery disclosed in this invention, including most of the operating steps in Example 1, with the following differences:

[0069] Comparative Examples 1 to 7 used the amounts of lithium-supplementing additives, lithium sulfonate compounds, and fluorinated solvents shown in Table 1 for Comparative Examples 1 to 7.

[0070] Performance testing

[0071] The following performance tests were performed on Examples 1-4 and Comparative Examples 1-7 prepared above:

[0072] Battery initial efficiency test:

[0073] After the battery is filled with electrolyte and allowed to stand for a period of time, it is charged at 25±2℃. First, a charging current of 0.02C is used for 2 hours; then, a 0.1C current is used for 5 hours; finally, a constant current and constant voltage charge of 0.5C is used to reach 4.45V, with a cutoff current of 0.02C. Discharge is then performed at 0.2C until the discharge cutoff voltage reaches 3.0V. The final initial efficiency EF = DC / (CC+CV), where DC is the discharge capacity, and CC+CV is the sum of the constant current and constant voltage capacity during charging.

[0074] 45℃ Cyclic Test:

[0075] The test method is as follows: Lithium-ion batteries are charged to 4.45V at a constant current and voltage of 1C in a constant temperature chamber at 45±2℃, with a cutoff current of 0.05C, and then discharged to 3V at 1C. Multiple charge-discharge cycles are performed under these conditions. The capacity retention rate is calculated after 300 and 500 cycles, with 5 batteries in each group.

[0076] Capacity retention rate (%) = Discharge capacity at corresponding cycle number (mAh) / Discharge capacity at the third cycle (mAh) * 100%

[0077] The average capacity retention rate of each group of 5 batteries after different cycles is recorded in Table 2.

[0078] Low-temperature discharge performance test: Under 25℃ conditions, the capacity-graded battery was discharged at 0.2C to 3.0V and left to stand for 5 minutes; then charged at 0.2C to 4.45V. When the cell voltage reached 4.45V, it was switched to constant voltage charging at 4.45V until the charging current was less than or equal to the given cutoff current of 0.05C, and left to stand for 5 minutes; the fully charged cell was transferred to a high-low temperature chamber, set to -20℃, and left to stand for 120 minutes after the chamber temperature was reached; then discharged at 0.2C to the cutoff voltage of 3.0V and left to stand for 5 minutes; the high-low temperature chamber temperature was then adjusted to 25℃±3℃, and left to stand for 60 minutes after the chamber temperature was reached; then charged at 0.2C to 4.45V. When the cell voltage reached 4.45V, it was switched to constant voltage charging at 4.45V until the charging current was less than or equal to the given cutoff current of 0.05C; left to stand for 5 minutes; the capacity retention rate at -20℃ low-temperature discharge of 3.0V was calculated. The calculation formula is as follows:

[0079] -20℃ discharge to 3.0V capacity retention rate (%) = (-20℃ discharge capacity to 3.0V / 25℃ discharge capacity to 3.0V) × 100%.

[0080] Battery high-temperature storage test:

[0081] The fully charged cell (charged to 4.45V at 0.7C constant current and constant voltage, with a cutoff current of 0.05C) was placed in an environment of 85℃ for 18 hours. After 12 hours, it was taken out and the hot thickness, voltage, and internal resistance were tested. It was then discharged to 3.0V at 0.2C constant current and cycled for 3 weeks to record the recovered capacity (the capacity of the third week was taken).

[0082] The test results are entered into Table 2.

[0083] Table 1

[0084] Test number Lithium supplement additive Lithium sulfonate compounds Fluorinated solvents Example 1 1％ 1％ 5％ Example 2 2％ 1％ 5％ Example 3 1％ 2％ 5％ Example 4 1％ 1％ 8％ Comparative Example 1 / / / Comparative Example 2 1％ / / Comparative Example 3 / 1％ / Comparative Example 4 / / 5％ Comparative Example 5 1％ 1％ / Comparative Example 6 / 1％ 5％ Comparative Example 7 1％ / 5％

[0085] Table 2

[0086]

[0087] As can be seen from the test results in Table 2, in Example 1, the combined use of lithium replenishing additive, lithium sulfonate compound, and fluorinated solvent comprehensively improved the battery performance; in Examples 2 and 3, the contents of lithium replenishing additive Li2NiO2, lithium sulfonate compound, and fluorinated solvent were adjusted. The increase in lithium replenishing additive improved the initial efficiency, the increase in lithium sulfonate compound improved the cycle performance, storage performance, and low-temperature discharge performance, and the increase in fluorinated solvent in Example 4 improved the high-temperature cycle performance.

[0088] Compared to Comparative Example 1, Comparative Example 2, with the addition of 1% lithium supplementation additive Li2NiO2, showed improved initial efficiency and slightly improved cycle performance, but its low-temperature discharge performance was affected. This is because the positive electrode lithium supplementation additive is unstable at high potentials and easily reacts with the electrolyte, increasing electrode interface impedance and deteriorating low-temperature discharge. There was no significant change in low-temperature discharge and high-temperature storage. In Comparative Example 3, the addition of lithium sulfonate compounds did not significantly change the initial efficiency, but improved cycle performance and low-temperature discharge, and somewhat improved high-temperature storage. This is based on the low impedance of the electrode interface film formed by the lithium sulfonate groups in the lithium sulfonate compounds, which improves low-temperature discharge, and the isocyanate groups, which remove water and acid, protecting the electrode interface and improving high-temperature storage. In Comparative Example 4, the addition of a fluorinated solvent did not significantly improve the initial coulombic efficiency and low-temperature discharge, but effectively improved… The high-temperature cycle performance and high-temperature storage performance of the battery are improved. This is because the fluorine atoms in the fluorinated solvent have strong electronegativity and weak polarity, which makes the fluorinated solvent have high oxidation resistance and thermal stability. Comparative Example 5 shows that the addition of lithium-replenishing additive Li2NiO2 and lithium sulfonate compounds significantly improves the cycle performance. Comparative Example 6 shows that the addition of lithium sulfonate compounds and fluorinated solvents improves the cycle performance and high-temperature storage performance to a certain extent. Comparative Example 7 shows that the addition of lithium-replenishing additives and fluorinated solvents improves the initial efficiency, cycle performance, and storage performance, while there is no significant change at low-temperature discharge. That is, in this invention, the combined use of lithium sulfonate compounds, lithium-replenishing additives, and fluorinated solvents can play a synergistic role, effectively improving the battery's initial efficiency, high-temperature cycle performance, high-temperature storage performance, and battery initial efficiency.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium-ion battery, characterized in that, The electrolyte comprises a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode active material layer, which includes a positive electrode active material and a lithium supplementation additive. The electrolyte includes a solvent, a lithium salt, and a lithium sulfonate compound. The solvent includes a fluorinated solvent, the structure of which is shown below: Z1 and Z2 are selected from fluoroalkyl groups with 1 to 5 carbon atoms; The general structural formula of the lithium sulfonate compounds is shown below: Where R is selected from hydrocarbon groups with 1-4 carbon atoms; The lithium supplement additive is selected from Li x M y O z , where 1≤x≤6, 1≤y≤6, 2≤z≤12, and M is one or more of Ni, Co, Fe, Cu, Al, Mn, Ti, P, Si, and C.

2. A lithium-ion battery according to claim 1, characterized in that, The fluorinated solvent includes one or more of the following compounds: The content of fluorinated solvents accounts for 3 to 15 wt% of the total solvent mass.

3. A lithium-ion battery according to claim 1, characterized in that, The lithium sulfonate compounds include one or more of the following compounds: Lithium methyl isocyanate sulfonate, lithium ethyl isocyanate sulfonate, lithium isopropyl cyanate sulfonate.

4. A lithium-ion battery according to claim 1, characterized in that, The lithium supplementation additive includes one or more of the following compounds: Li2NiO2, Li5FeO4, Li2MnO3, Li6CoO4, Li6MnO4.

5. A lithium-ion battery according to claim 1, characterized in that, Based on the total mass of the electrolyte (100%), the mass percentage of the lithium sulfonate compound is 0.01–10%.

6. A lithium-ion battery according to claim 1, characterized in that, Based on the total mass of the positive electrode as 100%, the mass percentage of the lithium supplementation additive is 0.01-10%.

7. A lithium-ion battery according to claim 1, characterized in that, It also includes film-forming additives, with the film-forming additives comprising 3 to 15% by mass, based on the total mass of the electrolyte as 100%.

8. A lithium-ion battery according to claim 7, characterized in that, The film-forming additive is one or more of vinylene carbonate and its derivatives, halogen-substituted cyclic carbonates, chelated orthoborates, and chelated orthophosphates.

9. A lithium-ion battery according to claim 1, characterized in that, The lithium salt is selected from one or more organic electrolyte salts and inorganic electrolyte salts, including LiPF6, LiBF4, LiSbF6, LiAsF6, LiTaF6, LiAlCl4, and Li2B. 10 Cl 10 Li2B 10 F 10 One or more of the following: LiClO4, LiCF3SO3, LiB(C2O4)2, LiB(O2CCH2CO2)2, LiB(O2CCF2CO2)2, LiB(C2O4)(O2CCH2CO2), LiB(C2O4)(O2CCF2CO2), LiP(C2O4)3, and LiP(O2CCF2CO2)3.

10. A lithium-ion battery according to claim 1, characterized in that, The positive electrode active material accounts for 80-99% of the mass of the positive electrode active material layer, and the positive electrode active material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and LiNi. x Co y Mn z One or more of O2; Where x + y + z = 1, x ≥ y.

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