Silicon-based negative electrode non-aqueous electrolyte and lithium ion battery

Abstract

The invention discloses a silicon-based negative electrode non-aqueous electrolyte and a lithium ion battery, the silicon-based negative electrode non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive, the additive comprises a compound A and a compound B shown as a formula 2, the compound A comprises at least one of a compound A1 and a compound A2 shown as a formula 1, # imgabs 0 #, one of m and n is 0, the other of m and n is 1, and the lithium salt is a non-aqueous organic solvent. R1 is selected from C1-C6 alkyl groups or C2-C6 alkenyl groups, R2 and R3 are respectively and independently selected from hydrogen or C1-C6 alkyl groups, R4 is selected from C1-C4 alkyl groups or C2-C4 alkenyl groups, R5-R9 are respectively and independently selected from halogen or hydrogen, and at least one of R5-R9 is halogen. Through the synergistic effect of the compound A and the compound B, the volume expansion stress of silicon is relieved, the quality of positive and negative electrode solid electrolyte membranes is improved, the interface side reaction of the electrolyte and an electrode at high temperature is reduced, the high-temperature storage performance and the high-temperature cycle performance of the lithium ion battery are finally improved, and the risk of lithium precipitation is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a non-aqueous electrolyte for a silicon-based negative electrode and a lithium-ion battery. Background Art

[0002] With the wide application of lithium-ion batteries in fields such as electric vehicles, energy storage systems, and consumer electronics, improving energy density and cycle stability has become a key research direction. Silicon (Si) negative electrodes are regarded as ideal materials to break through traditional graphite negative electrodes due to their extremely high theoretical specific capacity. However, during the lithium intercalation process, silicon undergoes a volume expansion of approximately 400%, resulting in pulverization of the electrode structure and repeated rupture and regeneration of the solid electrolyte interface (SEI) film, thereby causing continuous consumption of the electrolyte, an increase in internal resistance, and swelling of the battery thickness. These problems severely limit the long-cycle performance of silicon-based negative electrodes. Especially in high-temperature environments, the above challenges are more prominent, further restricting the application scope and development potential of silicon-based negative electrodes.

[0003] Currently, the academic and industrial communities have partially alleviated the volume effect of silicon-based negative electrodes through strategies such as nanosizing silicon particles, prelithiation, porous carbon matrix composites, and metal doping, and promoted the preliminary application of silicon-doped carbon negative electrodes. However, these methods still face challenges under high-temperature working conditions: on the one hand, high temperature accelerates the decomposition of the electrolyte and side reactions, exacerbating the instability of the SEI film; on the other hand, the volume expansion of silicon is more significant at high temperatures, further leading to deterioration of the interface between the electrode and the electrolyte, rapid growth of the battery internal resistance, and a significant decrease in cycle life. As a core component of the battery, the optimization of the non-aqueous electrolyte is crucial for suppressing the high-temperature failure of silicon-based negative electrodes. Existing non-aqueous electrolyte systems usually improve the mechanical stability of the SEI through film-forming additives (such as vinylene carbonate VC, fluorinated carbonate FEC, etc.), but the decomposition products of these additives at high temperatures are difficult to effectively inhibit the severe expansion of silicon and interfacial side reactions.

[0004] Therefore, there is an urgent need for a non-aqueous electrolyte for a silicon-based negative electrode and a lithium-ion battery to solve the deficiencies of the existing technology. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a non-aqueous electrolyte for a silicon-based negative electrode and a lithium-ion battery, which has good high-temperature storage performance and high-temperature cycle performance, and has no risk of lithium plating.

[0006] To achieve the above purpose, the present invention provides a non-aqueous electrolyte for a silicon-based negative electrode, comprising a lithium salt, a non-aqueous organic solvent, and an additive. The additive includes compound A and compound B shown in formula 2. Compound A includes at least one of compound A1 and compound A2 shown in formula 1.

[0007] Among them, one of m and n is 0, and the other of m and n is 1. R1 is selected from C1-C6 alkyl or C2-C6 alkenyl. R2 and R3 are each independently selected from hydrogen or C1-C6 alkyl. R4 is selected from C1-C4 alkyl or C2-C4 alkenyl. R5-R9 are each independently selected from halogen or hydrogen, and at least one of R5-R9 is halogen.

[0008] Compared with the prior art, the additive of the silicon-based anode non-aqueous electrolyte of the present invention includes compound A and compound B shown in Formula 2. Among them, compound A can polymerize on the surface of the anode to form a tough polymer layer, which can adapt to the repeated expansion and contraction of silicon particles during charge and discharge, thus effectively alleviating the mechanical stress caused by the volume change of the silicon-based anode and reducing the risk of lithium deposition. At the same time, the relatively electronegative O and N in compound A can scavenge acidic substances such as HF generated by LiPF6, reducing the chemical corrosion of the SEI film. Moreover, compound A does not contain carbonyl oxygen, thereby reducing its solvation with lithium ions, promoting the rapid desolvation and intercalation process of lithium ions, and further improving the lithium ion transport efficiency. In addition, compound B contains halogen atoms with strong electronegativity, which can preferentially be reduced at the anode to form a SEI film rich in lithium halide. The formed lithium halide layer not only has high mechanical strength and low electronic conductivity, can further effectively inhibit the continuous decomposition of the electrolyte, relieve the volume expansion stress of silicon, but also reduces the side reactions caused by trace moisture in the electrolyte due to the hydrophobicity of lithium halide, enhancing the interface stability. In addition, compound B has a fluorophenyl ether structure, which can polymerize at the cathode to form a CEI film, reducing the dissolution of transition metal elements in the cathode, while reducing the electrolyte viscosity and increasing the conductivity. Therefore, through the synergistic effect of compound A and compound B of the present invention, the volume expansion stress of silicon is alleviated, the quality of the solid electrolyte films on the positive and negative electrodes is improved, the interfacial side reactions between the electrolyte and the electrode at high temperature are reduced, and finally the high-temperature storage performance and high-temperature cycling performance of the lithium ion battery are improved and the risk of lithium deposition is reduced.

[0009] Further, R1 is selected from C1-C3 alkyl or C2-C3 alkenyl, R2 and R3 are both selected from hydrogen, R5-R9 are each independently selected from F or hydrogen, and one or both of R5-R9 are F.

[0010] Further, the compound A2 of the present invention includes at least one of compound 1 and compound 2: 。

[0011] Among them, the cas number of compound A1 is 251-69-4; the cas number of compound 1 is 76098-06-1; the cas number of compound 2 is 103460-78-2.

[0012] Further, the compound B of the present invention includes at least one of compound 3, compound 4, and compound 5: .

[0013] Among them, the cas number of compound 3 is 459-60-9; the cas number of compound 4 is: 351-93-9; the cas number of compound 5 is 75626-17-4.

[0014] Further, the mass percentage of the compound A of the present invention in the non-aqueous electrolyte of the silicon-based negative electrode is 0.05-5%; specifically, the mass percentage of the compound A in the non-aqueous electrolyte of the silicon-based negative electrode can be, but is not limited to, 0.05%, 0.1%, 0.5%, 0.8%, 1.2%, 1.6%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0015] Further, the mass percentage of the compound B of the present invention in the non-aqueous electrolyte of the silicon-based negative electrode is 0.05-5%. Specifically, the mass percentage of the compound B in the non-aqueous electrolyte of the silicon-based negative electrode can be, but is not limited to, 0.05%, 0.1%, 0.5%, 0.8%, 1.2%, 1.6%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%. By adjusting the ratio of the compound A and the compound B in the non-aqueous electrolyte of the silicon-based negative electrode, the quality of the solid electrolyte film of the positive and negative electrodes can be significantly improved, and the volume expansion stress of the silicon-based negative electrode material can be effectively relieved, thereby enhancing the stability of the electrode structure.

[0016] Further, the lithium salt of the present invention is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium lower aliphatic carboxylate, lithium difluorodioxalate phosphate (LiDFBP), lithium bis(fluorosulfonyl)imide (LiFSI), lithium chloroborane, and lithium tetraphenylborate.

[0017] Further, the mass percentage of the lithium salt of the present invention in the non-aqueous electrolyte of the silicon-based negative electrode is 5-25%; specifically, the mass percentage of the lithium salt in the non-aqueous electrolyte of the silicon-based negative electrode can be, but is not limited to, 5%, 8%, 12%, 16%, 19%, 22%, 25%.

[0018] Further, the non-aqueous organic solvent of the present invention is selected from at least one of γ-butyrolactone (GBL), γ-valerolactone (GVL), δ-valerolactone (DVL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), butyl acetate (BAC), propyl propionate (PP), propyl butyrate (PRB), ethylene carbonate (EC), propylene carbonate (PCA), butylene carbonate (BC), methyl pentyl carbonate (MPC), vinylene carbonate (VEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), propylene carbonate (PC), 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), dimethoxymethane (DMM), diethoxymethane (DEM), ethoxymethoxymethane (DCE), ethylene glycol di-n-propyl ether (EDP), ethylene glycol di-n-butyl ether (EDB), and diethylene glycol dimethyl ether (DEGME).

[0019] Further, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte for the silicon-based negative electrode of the present invention is 65% to 90%. Specifically, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte for the silicon-based negative electrode can be, but is not limited to, 65%, 70%, 75%, 80%, 85%, 90%.

[0020] Further, the non-aqueous electrolyte for the silicon-based negative electrode of the present invention further includes an auxiliary agent, and the auxiliary agent is selected from at least one of fluoroethylene carbonate (FEC), ethylene sulfite (ES), 1,3-propane sultone (PS), 1,3-propylene sulfonate (PES), 1,4-butane sultone (BS), disulfate ethylene ester (DTD), and succinic anhydride (SA).

[0021] Further, the mass percentage of the auxiliary agent in the non-aqueous electrolyte for the silicon-based negative electrode of the present invention is 0.05% to 5%. Specifically, the mass percentage of the auxiliary agent in the non-aqueous electrolyte for the silicon-based negative electrode can be, but is not limited to, 0.05%, 0.1%, 0.15%, 0.2%, 0.6%, 0.8%, 1.5%, 2%, 2.6%, 3.1%, 3.8%, 4.2%, 4.8%, 5%. Preferably, the mass percentage of the auxiliary agent in the non-aqueous electrolyte for the silicon-based negative electrode is 0.5% to 3%.

[0022] Correspondingly, the present invention also provides a lithium-ion battery, including a positive electrode and a negative electrode. The negative electrode is a silicon-based negative electrode, and the non-aqueous electrolyte for the silicon-based negative electrode mentioned above is further included. This lithium-ion battery has good high-temperature storage performance and high-temperature cycling performance, and has a low risk of lithium plating.

[0023] Further, the silicon-based negative electrode is any one of a silicon negative electrode, a silicon-carbon negative electrode, and a silicon-oxygen negative electrode. Specifically, the negative electrode sheet is obtained by coating a negative electrode paste on a current collector. The negative electrode paste includes a carbon-based material, CVD vapor-deposited pure silicon, a conductive agent, a binder, and a thickener. The mass ratio of the carbon-based material, silicon oxide compound, conductive agent, binder, and thickener is 72-78:18-22:1-3:0.5-1.5:0.5-1.5. Specifically, the carbon-based material can be, but is not limited to, at least one of artificial graphite and natural graphite. The binder can be, but is not limited to, styrene-butadiene rubber. The thickener can be, but is not limited to, sodium carboxymethyl cellulose (CMC).

[0024] Further, the positive electrode of the present invention includes a positive electrode material, and the positive electrode material is selected from at least one of nickel cobalt manganese oxide, nickel cobalt aluminum oxide, and lithium cobalt oxide. Specifically, the positive electrode material can be nickel cobalt manganese oxide, and its chemical formula can be LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2、 LiNi 0.9 Co 0.05 Mn 0.05 O2 or LiNi x Co y Mn z M (1-x-y-z) O2; for another example, the positive electrode material can be nickel cobalt aluminum oxide, and its chemical formula can be LiNi x Co y Al z N (1-x-y-z) O2, where M and N are each independently selected from at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1; further, for example, the positive electrode material is lithium cobalt oxide, and its chemical formula is LiCoO2. As an example, the positive electrode material of the present invention is LiNi 0.9 Co 0.05 Mn 0.05 O2. Specific Embodiments

[0025] To better illustrate the purpose, technical solution, and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following described methods are further explanatory descriptions of the present invention and should not be construed as limitations on the present invention.

[0026] Example 1 (1) Preparation of non-aqueous electrolyte for silicon-based anode In a glove box filled with argon (O2 < 1 ppm, H2O < 1 ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl acetate (MA), and diethyl carbonate (DEC) were mixed according to a weight ratio of EC:EMC:MA:DEC = 2:16:7:1 to obtain 86.5 g of non-aqueous organic solvent. Then, 0.5 g of Compound 1 and 0.5 g of Compound 5 were added, dissolved, and stirred well. After that, 12.5 g of lithium hexafluorophosphate was added, and the mixture was stirred evenly to obtain the non-aqueous electrolyte for silicon-based anode.

[0027] (2) Preparation of positive electrode sheet NCM9055 (LiNi 0.9 Co 0.05 Mn 0.05 O2), binder PVDF, and conductive agent SuperP were mixed evenly according to a mass ratio of 95:1:4 to prepare a lithium-ion battery positive electrode slurry with a certain viscosity. The prepared slurry was coated on both sides of the aluminum foil, dried, and rolled to obtain the positive electrode sheet.

[0028] (3) Preparation of negative electrode sheet Artificial graphite, CVD pure silicon, conductive agent Ketjenblack, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose (CMC) were fully stirred and mixed evenly in a deionized water solvent system according to a mass ratio of 76:20:2:1:1, and then coated on the copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0029] (4) Preparation of lithium-ion battery The positive electrode sheet, separator, and negative electrode sheet were wound to form a soft-pack battery cell, which was packaged with a polymer aluminum-plastic film and filled with the above-prepared non-aqueous electrolyte for silicon-based anode. After processes such as formation and grading, a lithium-ion battery with a capacity of 1000 mAh was prepared.

[0030] The formulations of the non-aqueous electrolytes for silicon-based anodes in Examples 1 - 10 and Comparative Examples 1 - 5 are shown in Table 1. The steps for preparing the silicon-based electrolyte and the battery in Examples 2 - 10 and Comparative Examples 1 - 5 are the same as those in Example 1.

[0031] Table 1 Formulations of non-aqueous electrolytes for silicon-based anodes in each example and comparative example

[0032] The structures of Compound 6 and Compound 7 are shown as follows:

[0033] The lithium-ion batteries prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were respectively subjected to high-temperature cycle tests, internal resistance growth rate tests, thickness growth rate tests, and lithium plating tests. The specific test conditions are as follows, and the performance test results are shown in Table 2.

[0034] High-temperature cycle capacity retention performance test: At a constant temperature of 25°C, the lithium-ion battery was charged at a constant current of 1C until the voltage reached 4.2V, then charged at a constant voltage of 4.2V until the current reached 0.05C, and then discharged at a constant current of 1C until the voltage reached 3.0V. The initial discharge capacity of the battery was recorded as C0. Then, the lithium-ion battery was placed in a constant temperature oven at 45°C and left to stand for 30 minutes to reach a constant temperature. Then, after 300 charge-discharge cycles at 1C / 1C at 45°C, it was discharged at a constant current and constant voltage of 1C / 1C at 25°C until 3V. The discharge capacity was recorded as C1. The capacity retention rate of the lithium-ion battery for 300 cycles at 45°C was calculated using the following formula.

[0035] Capacity retention rate = C1 / C0 × 100%.

[0036] Internal resistance growth rate test: At a constant temperature of 25°C, the lithium-ion battery was charged at a constant current of 0.5C until the cut-off voltage of 4.2V, and the initial internal resistance of the battery was recorded. Then, the lithium-ion battery was placed in a constant temperature oven at 60°C and left to stand for 30 minutes to reach a constant temperature, and then stored for 30 days. After that, at 25°C, the battery after 30 days of storage was charged at a constant current and constant voltage of 0.5C until the cut-off voltage of 4.2V at room temperature, and then discharged at a constant current and constant voltage until the capacity dropped to 50% SOC to test the internal resistance of the battery after 30 days of storage.

[0037] Internal resistance growth rate = (Internal resistance of the battery after 30 days of storage - Initial internal resistance) / Initial internal resistance × 100%.

[0038] Thickness growth rate test: After the battery was charged at a constant current and constant voltage of 0.5C to 4.2V at 25°C, the mass of the fully charged battery was measured using the drainage method and recorded as m1. After being stored at 60°C for 30D, it was taken out and the mass of the battery was measured using the drainage method after discharging at a constant current of 0.5C to 3V at room temperature of 25°C and recorded as m2.

[0039] Thickness growth rate of the battery after 30 days of high-temperature storage = (Thickness of the battery after 30 days of storage m2 - Thickness of the battery when fully charged for the first time m1) / Thickness of the battery when fully charged for the first time m1 × 100%.

[0040] Lithium plating situation test: At a high temperature of 45 °C, ① charge at a constant current of 1C at constant voltage to 4.2V, with a cut-off rate of 0.05C, and let it stand for 5 minutes; ② discharge at a constant current of 1C to 3V, and let it stand for 5 minutes; ③ repeat steps ① to ② for a total of 100 times; ④ charge at a constant current of 1C at constant voltage to 4.2V, with a cut-off rate of 0.05C, and let it stand for 5 minutes; ⑤ disassemble the interface and observe the lithium deposition situation.

[0041] Table 2 Performance test results of lithium-ion batteries

[0042] As can be seen from Table 2, compared with Comparative Examples 1 to 5, the lithium-ion batteries of Examples 1 to 10 have better high-temperature storage performance and high-temperature cycling performance. This is because the additives in the non-aqueous electrolyte of the silicon-based anode of the present invention include Compound A and Compound B shown in Formula 2. Among them, Compound A can polymerize on the surface of the anode to form a tough polymer layer. This polymer layer can adapt to the repeated expansion and contraction of silicon particles during charge and discharge, thereby effectively alleviating the mechanical stress caused by the volume change of the silicon-based anode and reducing the risk of lithium deposition; at the same time, the highly electronegative O and N in Compound A can scavenge acidic substances such as HF generated by LiPF6, reducing the chemical corrosion of the SEI film; moreover, Compound A does not contain carbonyl oxygen, thereby reducing its solvation effect with lithium ions, promoting the rapid desolvation and intercalation process of lithium ions, and further improving the lithium-ion transport efficiency. In addition, Compound B contains halogen atoms with strong electronegativity, which can preferentially reduce at the anode to form an SEI film rich in lithium halide. The formed lithium halide layer not only has high mechanical strength and low electronic conductivity, can further effectively inhibit the continuous decomposition of the electrolyte, alleviate the volume expansion stress of silicon, but also reduces the side reactions caused by trace moisture in the electrolyte due to the hydrophobicity of lithium halide, enhancing the interface stability. In addition, Compound B has a fluorophenyl ether structure, which can polymerize at the cathode to form a CEI film, reducing the dissolution of transition metal elements in the cathode, while reducing the electrolyte viscosity and increasing the conductivity. Therefore, through the synergistic effect of Compound A and Compound B of the present invention, the volume expansion stress of silicon is alleviated, the quality of the solid electrolyte films on the positive and negative electrodes is improved, the interfacial side reactions between the electrolyte and the electrode at high temperature are reduced, and finally the high-temperature storage performance and high-temperature cycling performance of the lithium-ion battery are improved and the risk of lithium deposition is reduced.

[0043] Comparing Example 4 with Comparative Examples 2 to 3 shows that removing any one of Compound A and Compound B will significantly deteriorate the electrical performance of the lithium-ion battery, indicating that both Compound A and Compound B are key components for improving the performance of the lithium-ion battery, and there is a synergistic effect between them.

[0044] Comparing Example 4 with Comparative Example 4, it can be seen that the electrical performance of the lithium-ion battery in Example 4 is superior to that in Comparative Example 4. This is because there is a carbonyl oxygen in Compound 6, which increases its solvation ability with lithium ions. Therefore, when lithium ions are transported to the negative electrode, they will not be desolvated and embedded in the negative electrode relatively quickly, resulting in slight lithium precipitation on the negative electrode.

[0045] Comparing Example 4 with Comparative Example 5, it can be seen that the electrical performance of the lithium-ion battery in Example 4 is superior to that in Comparative Example 5. This is because Compound 7 does not belong to the fluorophenyl ether structure, and it cannot reduce the viscosity of the electrolyte and improve the conductivity of the electrolyte, resulting in slight lithium precipitation on the negative electrode.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it is not limited to only the embodiments listed. Those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A non-aqueous electrolyte for a silicon-based negative electrode, comprising a lithium salt, a non-aqueous organic solvent, and an additive, characterized in that, The additive includes compound A and compound B shown in Formula 2, and compound A includes at least one of compound A1 and compound A2 shown in Formula 1. Wherein, one of m and n is 0 and the other is 1, R1 is selected from C1-C6 alkyl or C2-C6 alkenyl, R2 and R3 are each independently selected from hydrogen or C1-C6 alkyl, R4 is selected from C1-C4 alkyl or C2-C4 alkenyl, and R5-R9 are each independently selected from halogen or hydrogen and at least one of R5-R9 is halogen.

2. The non-aqueous electrolyte for a silicon-based anode according to claim 1, characterized in that, R1 is selected from C1-C3 alkyl or C2-C3 alkenyl, R2 and R3 are both selected from hydrogen, R5-R9 are each independently selected from F or hydrogen, and one or both of R5-R9 are F.

3. The non-aqueous electrolyte for a silicon-based anode according to claim 1, characterized in that, Compound A2 includes at least one of compound 1 and compound 2: 。 4. The non-aqueous electrolyte for the silicon-based negative electrode according to claim 1, characterized in that, Compound B includes at least one of compound 3, compound 4, and compound 5: 。 5. The non-aqueous electrolyte for a silicon-based anode according to claim 1, characterized in that, The mass percentage of compound A in the non-aqueous electrolyte of the silicon-based negative electrode is 0.05-5%; the mass percentage of compound B in the non-aqueous electrolyte of the silicon-based negative electrode is 0.05-5%.

6. The non-aqueous electrolyte for a silicon-based anode according to claim 1, characterized in that, The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium lower aliphatic carboxylate, lithium difluoro(bis(oxalato)phosphate), lithium bis(fluorosulfonyl)imide, lithium chloroborane, and lithium tetraphenylborate.

7. The non-aqueous electrolyte for silicon-based negative electrode according to claim 1, wherein The non-aqueous organic solvent is selected from at least one of γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, methyl pentyl carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, propylene carbonate, 1,3-dioxolane, 1,4-dioxane, crown ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2-trifluoromethyltetrahydrofuran, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

8. The non-aqueous electrolyte for a silicon-based negative electrode according to claim 1, characterized in that, It also includes an auxiliary agent, and the auxiliary agent is selected from at least one of fluoroethylene carbonate, ethylene sulfite, 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, ethylene sulfate, and succinic anhydride.

9. A lithium-ion battery, comprising a positive electrode and a negative electrode, wherein the negative electrode is a silicon-based negative electrode, characterized in that, It also includes the non-aqueous electrolyte of the silicon-based negative electrode according to any one of claims 1-8.

10. The lithium ion battery according to claim 9, characterized in that, The silicon-based negative electrode is any one of a silicon negative electrode, a silicon-carbon negative electrode, and a silicon-oxygen negative electrode.

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