Silicon-based negative electrode electrolyte, preparation method and application thereof

Abstract

The application discloses a silicon-based negative electrode electrolyte, a preparation method and application thereof, and is a novel electrolyte which can form a special solvation structure and stabilize an electrode interface. The electrolyte replaces ester solvents with ether solvents to prevent the reaction between lithiated silicon and carbonates, and selects a single-oxygen ether as a main solvent in the electrolyte. The single-oxygen ether has an ether bond at only one end, so that the solvent molecules have weak coordination with lithium ions, while the anion groups in lithium salts have strong coordination with lithium ions. A contact ion pair (CIP) and an aggregate ion pair (AGG) solvation structure are formed in the electrolyte, more anion groups participate in the SEI process, an interface layer rich in inorganic components is formed on the electrode surface, and the cycle of the electrode is stabilized.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion secondary batteries and electrochemistry, and relates to a silicon-based negative electrode electrolyte, its preparation method and application. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density and environmental friendliness, have been widely used in new energy vehicles, 3C electronics, and other fields. As their applications deepen, the demand for high energy density becomes increasingly urgent. However, the theoretical specific capacity of currently widely used graphite anodes is only 372 mAh / g, making the search for next-generation anode materials with high specific capacity a common consensus.

[0003] Silicon is abundant in resources, has a low operating voltage (0.4V vs Li / Li+), and a high theoretical specific capacity (4200mAh g). -1 Silicon-carbon anodes, with their advantages such as high specific capacity and low conductivity, are promising anode materials for developing high-energy-density lithium-ion batteries. However, pure silicon is a semiconductor with poor conductivity, and after lithiation, it undergoes extreme volume expansion (>300%), preventing the formation of a stable solid-state electrolyte interface on the electrode surface and hindering the continuous reaction between the electrolyte and the electrode, leading to rapid capacity decay. Silicon-carbon anodes maintain the high specific capacity of silicon while the introduction of carbon materials improves conductivity and alleviates the volume expansion of silicon, making them the closest silicon-based anode material to practical application. However, the carbonate electrolytes currently used in commercial silicon-carbon anode applications cannot form a stable SEI interface to achieve high cycle performance. The main reason is that lithiated silicon has nucleophilic properties, tending to attack the nucleophilic carbon groups in the carbonyl groups of the carbonate solvent, leading to continuous SEI thickening and lithium consumption, resulting in rapid battery failure. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a silicon-based negative electrode electrolyte, its preparation method and application, so as to solve the problem that carbonate electrolytes in the prior art cannot form a stable SEI interface to achieve high cycle performance.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] An electrolyte that can be used in silicon-based anodes includes a lithium salt, an organic solvent, and an additive, wherein the organic solvent is a monooxyether compound and the monooxyether compound accounts for 80-95% of the volume in the electrolyte.

[0007] The chemical structural formula of the monooxyether compound is as follows:

[0008]

[0009] M is one of ethyl group, propyl group, butyl group, pentyl group, hexyl group or heptyl group.

[0010] Further improvement of the present application is:

[0011] Preferably, the volume ratio of the additive in the electrolyte is 5-20%.

[0012] Preferably, the concentration of the lithium salt in the electrolyte is 0.25-1 mol / L.

[0013] Preferably, the single oxygen ether compound is methyl ethyl ether, methyl n-propyl ether, methyl n-butyl ether, methyl n-pentyl ether, methyl n-hexyl ether or methyl n-heptyl ether.

[0014] Preferably, the additive is one or more of vinylene carbonate, fluoroethylene carbonate and vinyl sulfate carbonate.

[0015] Preferably, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate and lithium bis(fluorosulfonyl)imide.

[0016] Preferably, the organic solvent is methyl tert-butyl ether.

[0017] Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide or lithium difluoro(oxalato)borate.

[0018] A preparation method of the above-mentioned any one for silicon-based negative electrode electrolyte, under the protection of inert gas Ar, dissolving lithium salt in single oxygen ether compound, stirring to obtain ether electrolyte, dissolving additive in ether electrolyte, stirring to obtain colorless transparent liquid as silicon-based negative electrode electrolyte.

[0019] The above-mentioned application for silicon-based negative electrode electrolyte is used in lithium ion battery.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application discloses a silicon-based negative electrode electrolyte, which is a new type of electrolyte capable of forming a special solvation structure and stabilizing the electrode interface. The electrolyte uses ether solvent instead of ester solvent to prevent the reaction of lithiated silicon and carbonate. Single oxygen ether is selected as the main solvent in the electrolyte. Single oxygen ether has an ether bond at one end, resulting in weak coordination between the solvent molecule and lithium ion, while the anion group in the lithium salt has strong coordination with lithium ion. The electrolyte forms contact ion pair (CIP) and aggregate ion pair (AGG) solvation structure inside, more anion groups participate in the SEI process, and an interface layer rich in inorganic components is formed on the electrode surface, thereby stabilizing the electrode cycle.

[0022] Further, the single-oxygen ether compound M has asymmetry, one end has a lithiumophilic ether bond, and the other end has a lithiumophobie alkyl group. The coordination strength of the single-oxygen ether solvent molecule with lithium ions is weakened, and the anion group in the lithium salt competes with it more easily to coordinate with lithium ions, thereby forming a contact ion pair (CIP), an aggregate ion pair (AGG) solvation structure, prompting the SEI film formed by the reaction of the electrode and the electrolyte to be converted from the organic components decomposed by the solvent to the inorganic components decomposed by the anion group in the lithium salt, while effectively reducing the interface impedance of the battery, inhibiting the occurrence of battery side reactions, thereby reducing the consumption of active lithium ions in the lithium ion battery and reducing the initial capacity loss of the lithium ion battery.

[0023] Further, when the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, the TFSI anion will form a CIP, AGG solvation structure with lithium ions, participate in the SEI formation process to produce more inorganic components (such as LiF and Li2O, etc.), and the interface layer formed by the inorganic components has higher compactness and high mechanical strength, preventing electron tunneling to cause further electrolyte decomposition, while relieving the volume change of the silicon material and improving the cycle performance of the lithium ion battery. By introducing a small amount of additive, the cycle life of the battery can be improved, and the positive electrode film former can be introduced to adapt to the full battery.

[0024] The application also discloses a preparation method of the interface-stable electrolyte, which only needs to uniformly mix and stir lithium salt, an organic solvent and an additive to obtain the electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Raman spectra of the single-oxygen ether M1 of Example 1 and the dioxygen ether ethylene glycol dimethyl ether salt of Comparative Example 1 before and after salt dissolution.

[0026] Figure 2 Impedance spectra of the silicon-carbon negative electrode of the silicon-based negative electrode half-cell of the single-oxygen ether M1 electrolyte of Example 1 and the dioxygen ether ethylene glycol dimethyl ether of Comparative Example 1 after cycles 1, 20, 50 and 100.

[0027] Wherein, (a) is the impedance graph after cycle of Comparative Example 1; (b) is the impedance graph after cycle of Example 1.

[0028] Figure 3 SEM graphs of the silicon-carbon negative electrode of the silicon-based negative electrode half-cell of the single-oxygen ether M1 electrolyte of Example 1 and the dioxygen ether ethylene glycol dimethyl ether of Comparative Example 1 after cycle 100.

[0029] Wherein, (a) is Comparative Example 1 and the enlarged view; (b) is Example 1 and the enlarged view.

[0030] Figure 4 Figure 1 is a graph of the cycle performance of the silicon-based negative electrode half-cell 100 of Comparative Example 1 dioxy ether ethylene glycol dimethyl ether.

[0031] Figure 5 Figure 1 is a graph of the cycle performance of the silicon-based negative electrode half-cell 100 of Comparative Example 1 dioxy ether ethylene glycol dimethyl ether.

[0032] Figure 6 Figure 1 is a graph of the cycle performance of the silicon-based negative electrode half-cell 100 of Comparative Example 1 dioxy ether ethylene glycol dimethyl ether.

[0033] Figure 7 Figure 1 is a graph of the cycle performance of the silicon-based negative electrode half-cell 100 of Comparative Example 1 dioxy ether ethylene glycol dimethyl ether.

[0034] Figure 8 Figure 1 is a graph of the cycle performance of the silicon-based negative electrode half-cell 100 of Comparative Example 1 dioxy ether ethylene glycol dimethyl ether. DETAILED DESCRIPTION

[0035] The application will be further described in detail below in conjunction with the accompanying drawings and specific examples:

[0036] The application discloses a silicon-based negative electrode electrolyte, which comprises a lithium salt, an organic solvent and an additive. The organic solvent is a monooxy ether solvent containing an oxygen atom at one end, and has a structural formula as shown in the following formula (I):

[0037] The functional group M of the monooxy ether solvent is one of an ethyl group, a propyl group (including a normal propyl group and an isopropyl group), a butyl group (including a normal butyl group, an isobutyl group, a sec-butyl group and a tert-butyl group), a pentyl group (including eight kinds of normal pentyl groups), a hexyl group (including seventeen kinds of normal hexyl groups) or a heptyl group (including thirty-nine kinds of normal heptyl groups). More preferably, the content of the monooxy ether solvent accounts for 80-95% of the total volume of the electrolyte.

[0038] Preferably, the monooxy ether compound is selected from the following compounds and isomers thereof:

[0039]

[0040]

[0041] Preferably, in order to further improve the electrochemical performance of the electrolyte, a liquid additive is introduced, and the liquid additive can comprise one or more of vinylene carbonate, fluoroethylene carbonate, vinyl sulfate and vinylene carbonate, and the content of the liquid additive accounts for 5-20% of the total volume of the electrolyte.

[0042] Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, lithium bis(fluorosulfonyl)imide, or one or more of the above, and more preferably, the concentration of the lithium salt is 0.25 mol / L-1 mol / L.

[0043] Preferably, the organic solvent is selected from methyl ethyl ether (MA), methyl n-propyl ether (MB), methyl t-butyl ether (M1), methyl n-amyl ether (MC), methyl n-hexyl ether, methyl n-heptyl ether, or one or more of the above, and the reason for the selection is that the main chain length is suitable for use as a solvent.

[0044] One of the embodiments of the present application discloses a preparation method of a silicon-based negative electrode electrolyte, which comprises mixing, under anhydrous and oxygen-free conditions, a lithium salt after water removal, an organic solvent, and an additive, and uniformly stirring to obtain an interfacially stable electrolyte.

[0045] The specific preparation method is as follows: under the protection of inert gas Ar, a lithium salt is dissolved in an ether solvent at a certain concentration, stirred and dissolved to obtain an ether electrolyte, then a certain amount of additive is dissolved in the above ether electrolyte, stirred for a period of time, and a colorless transparent liquid is obtained to assemble a battery.

[0046] The application of the above-mentioned interfacially stable electrolyte in a lithium ion battery, which comprises a positive electrode sheet, a negative electrode sheet, a separator, and the lithium ion battery electrolyte of the present application.

[0047] The negative electrode material of the lithium ion battery is a silicon-based negative electrode and a lithium metal negative electrode, and the matching positive electrode material can be a metal oxide type (such as lithium cobaltate, lithium nickelate, lithium manganate, etc.), a polyanion salt type (such as lithium iron phosphate, lithium manganese phosphate, etc.), a compound type (such as nickel trifluoride, titanium disulfide, etc.).

[0048] Furthermore, the electrolyte embodiment is respectively used in a silicon-based negative electrode half-cell and a silicon-based full cell, the silicon-based negative electrode half-cell mainly comprises a lithium metal electrode sheet, a silicon-based electrode sheet, a separator, and an electrolyte. Among them, the silicon-based electrode sheet comprises a negative electrode current collector and a silicon-based active material coated on the surface of the negative electrode current collector, and the counter electrode material is a lithium metal material, and the experimental electrode is a silicon-based material; the silicon-based negative electrode full cell mainly comprises a silicon-based electrode sheet, a positive electrode sheet, a separator, and an electrolyte, wherein the ternary positive electrode material is selected in the present embodiment and the comparative example.

[0049] The principle of realizing interface stability and significantly improving cycle performance of the electrolyte is as follows: for the silicon-based negative electrode half-cell and the silicon-based negative electrode full-cell of the electrolyte, when the methyl tert-butyl ether compound is used as the solvent, the coordination of lithium ions and the solvent molecules is weakened, and more anion groups in the lithium salt are coordinated to form contact ion pairs (CIP) and aggregate ion (AGG) solvation structures. The electrolyte with the two solvation structures is decomposed at the electrode interface to generate more inorganic components, the SEI interface stability is improved, the continuous decomposition of the electrolyte is prevented, and the stability is significantly improved.

[0050] The application will be further described below in combination with the comparative examples and the examples.

[0051] Comparative Example 1

[0052] Electrolyte configuration: in an argon-filled glove box, an organic solvent ethylene glycol dimethyl ether (DME) was used as a solvent, and then lithium bis-trifluoromethanesulfonimide was added, the concentration was 1 mol / L, and after stirring uniformly, the lithium ion battery electrolyte of Comparative Example 1 was obtained. The solvation structure of Comparative Example 1 was characterized by in-situ Raman spectroscopy Figure 1 ), and the results showed that lithium ions almost only coordinated with solvent molecules, and a large number of TFSI anion groups in the lithium salt did not participate in coordination.

[0053] Comparative Example 2

[0054] Electrolyte configuration: in an argon-filled glove box, an organic solvent ethylene carbonate / diethyl carbonate (EC / DEC) with a volume ratio of 1:1 was used as a solvent, and then lithium hexafluorophosphate was added, the concentration was 1 mol / L, and after stirring uniformly, the lithium ion battery electrolyte of Comparative Example 2 was obtained.

[0055] Comparative Example 3

[0056] Electrolyte configuration: in an argon-filled glove box, an organic solvent EC / DEC (volume ratio 1:1) was used as a solvent, and then 10% of the total volume of the electrolyte was added to fluoroethylene carbonate (FEC), and then lithium bis-trifluoromethanesulfonimide was added, the concentration was 1 mol / L, and after stirring uniformly, the lithium ion battery electrolyte of Comparative Example 3 was obtained.

[0057] Example 1

[0058] Electrolyte configuration: in an argon-filled glove box, an organic solvent methyl tert-butyl ether (MI) was used as a solvent, and then lithium bis-trifluoromethanesulfonimide was added, the concentration was 1 mol / L, and after stirring uniformly, the lithium ion battery electrolyte of Example 1 was obtained. The solvation structure of Example 1 was characterized by in-situ Raman spectroscopy Figure 1 ), and the results showed that a large number of lithium ions were coordinated with anion groups in the lithium salt to form contact ion pairs (CIP) and aggregate ion pairs (AGG) solvation structures.

[0059] Example 2

[0060] The electrolyte is configured as follows: in an argon-filled glove box, methyl tert-butyl ether (MTBE) is used as a solvent, FEC accounts for 5% of the total volume of the electrolyte, MTBE and FEC make up 100% of the electrolyte, lithium bis (trifluoromethanesulfonyl) imide is added, the concentration is 1 mol / L, and after stirring evenly, the lithium ion battery electrolyte of Example 2 is obtained.

[0061] Example 3

[0062] The electrolyte is configured as follows: in an argon-filled glove box, methyl tert-butyl ether (MTBE) is used as a solvent, FEC accounts for 10% of the total volume of the electrolyte, MTBE and FEC make up 100% of the electrolyte, lithium bis (trifluoromethanesulfonyl) imide is added, the concentration is 1 mol / L, and after stirring evenly, the lithium ion battery electrolyte of Example 3 is obtained.

[0063] Example 4

[0064] The electrolyte is configured as follows: in an argon-filled glove box, methyl tert-butyl ether (MTBE) is used as a solvent, FEC accounts for 20% of the total volume of the electrolyte, MTBE and FEC make up 100% of the electrolyte, lithium bis (trifluoromethanesulfonyl) imide is added, the concentration is 1 mol / L, and after stirring evenly, the lithium ion battery electrolyte of Example 4 is obtained.

[0065] Example 5

[0066] The electrolyte is configured as follows: in an argon-filled glove box, methyl tert-butyl ether (MTBE) is used as a solvent, FEC accounts for 10% of the total volume of the electrolyte, MTBE and FEC make up 100% of the electrolyte, lithium bis (trifluoromethanesulfonyl) imide is added, the concentration is 1 mol / L, and after stirring evenly, the lithium ion battery electrolyte of Example 5 is obtained.

[0067] Example 6

[0068] The electrolyte is configured as follows: in an argon-filled glove box, methyl tert-butyl ether (MTBE) is used as a solvent, FEC accounts for 10% of the total volume of the electrolyte, MTBE and FEC make up 100% of the electrolyte, lithium bis (trifluoromethanesulfonyl) imide is added, the concentration is 1 mol / L, and after stirring evenly, the lithium ion battery electrolyte of Example 6 is obtained.

[0069] Example 7

[0070] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 10% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 1mol / L, then add lithium difluoro (oxalato) borate, the concentration is 0.25mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained

[0071] Example 8

[0072] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 92% in the total volume of electrolyte, then add 8% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 0.35mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained.

[0073] Example 9

[0074] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 88% in the total volume of electrolyte, then add 12% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 0.65mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained.

[0075] Example 10

[0076] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 82% in the total volume of electrolyte, then add 18% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 0.8mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained.

[0077] Example 11

[0078] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 88% in the total volume of electrolyte, then add 12% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 0.65mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained.

[0079] Example 12

[0080] Electrolyte configuration: in the glove box filled with argon, methyl tert-butyl ether (MI) as the solvent, 88% in the total volume of electrolyte, then add 12% FEC in the total volume of electrolyte, methyl tert-butyl ether and FEC make up 100% of the electrolyte, then add lithium bis (trifluoromethanesulfonyl) imide, the concentration is 0.65mol / L, after stirring evenly, the lithium ion battery electrolyte is obtained.

[0081] Example 13

[0082] The electrolyte was prepared in an argon-filled glove box by dissolving LiTFSI in methyl n-hexyl ether (MD) to give a 0.25 mol / L solution, and then stirring to obtain the electrolyte of Example 14.

[0083] Example 14

[0084] The electrolyte was prepared in an argon-filled glove box by dissolving LiTFSI in methyl n-hexyl ether (MD) to give a 0.25 mol / L solution, and then stirring to obtain the electrolyte of Example 14.

[0085] Example 15

[0086] The electrolyte was prepared in an argon-filled glove box by dissolving LiTFSI in methyl n-hexyl ether (MD) to give a 0.25 mol / L solution, and then stirring to obtain the electrolyte of Example 14.

[0087] Table 1: Test results of electrochemical performance of lithium-silicon carbon half-batteries of some examples

[0088]

[0089]

[0090] Comparative Example 1 Figure 4 ) and Experimental Example 1 Figure 5 ), it can be concluded that the mono-oxygen ether methyl tert-butyl ether (MI) as an electrolyte solvent compared with the di-oxygen ether dimethyl ether (DME) as an electrolyte solvent for lithium metal-silicon carbon half-batteries, the 100th cycle capacity retention rate is increased by 10 times; further comparing the impedance Figure 2 ) of the two after 1, 20, 50 and 100 cycles, the interface impedance of Comparative Example 1 increases rapidly with the increase of cycle number. While the interface impedance of Experimental Example 1 remains almost unchanged with the increase of cycle number; SEM analysis of the electrode sheets after 100 cycles of the two Figure 3), it can be seen that the comparative example 1 produces a network of cracks, while the electrode surface of example 1 is smooth and complete; these prove the role of the single oxygen ether in stabilizing the battery interface and improving the cycle stability. Further comparison of comparative example 2 and example 1 can be made to obtain more excellent cycle stability of the single oxygen ether compared with the ester solvent. Comparison of experimental example 1 with experimental examples 2, 3 and 4 shows that the introduction of FEC significantly improves the cycle stability of the single oxygen ether. Comparative example 3 and experimental examples 2, 3 and 4 show that the cycle performance of the single oxygen ether is also superior to the ester solvent after the introduction of FEC, and the cycle performance is optimal when the volume ratio of FEC is 10%. In order to use the electrolyte for full cells, lithium difluoro(oxalato)borate (LiDFOB) is introduced as a positive electrode film-forming lithium salt. By comparing examples 3 and 5, 6 and 7, it is found that the introduction of a small amount of LiDFOB helps to further improve the cycle performance, and the optimal concentration is 0.25 mol / L.

[0091] The electrolyte of examples 6 and 7 with better electrochemical performance is selected to adapt to the full cell ( Figure 7 、 Figure 8 ), it can be found that the discharge capacity and stability of examples 6 and 7 are better than those of comparative example 3.

[0092] In summary, the present application develops a new type of asymmetric single oxygen ether, which can promote the coordination of anion groups in lithium salt and lithium ions by weakening the coordination of solvent molecules and lithium ions, regulate the formation of SEI, improve the cycle stability of silicon-based negative electrode, and introduce corresponding lithium salt and additives to achieve a high capacity retention rate of 90.3% of the silicon-based negative electrode half-cell at 0.5C rate after 300 cycles ( Figure 6 ), and also shows more excellent electrochemical performance than commercial electrolyte in full cells.

[0093] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A silicon-based negative electrode electrolyte, characterized in that, It includes lithium salt, organic solvent, and additives, wherein the organic solvent is a monooxyether compound, and the monooxyether compound accounts for 80-95% of the volume in the electrolyte; The chemical structural formula of the monooxyether compound is as follows: Wherein, M is one of an ethyl group, propyl group, butyl group, pentyl group, hexyl group or heptyl group; The monooxy ether compounds are methyl ethyl ether, methyl n-propyl ether, methyl n-butyl ether, methyl n-pentyl ether, methyl n-hexyl ether, or methyl n-heptyl ether.

2. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The additive accounts for 5-20% of the volume of the electrolyte.

3. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The concentration of the lithium salt in the electrolyte is 0.25 mol / L to 1 mol / L.

4. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The additive is one or more of ethylene carbonate, fluoroethylene carbonate, and ethylene sulfate.

5. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium dioxalate borate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium bis(trifluoromethanesulfonyl)imide.

6. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The organic solvent is methyl tert-butyl ether.

7. The silicon-based negative electrode electrolyte according to claim 1, characterized in that, The lithium salt is lithium bis(trifluoromethanesulfonylimide) or lithium difluorooxalateborate.

8. A method for preparing a silicon-based negative electrode electrolyte as described in any one of claims 1-7, characterized in that, Under the protection of inert gas Ar, lithium salt is dissolved in monooxy ether compounds. After stirring and dissolving, an ether electrolyte is obtained. Additives are dissolved in the ether electrolyte and stirred to obtain a colorless and transparent liquid, which is a silicon-based negative electrode electrolyte.

9. An application of the method described in any one of claims 1-7 in a silicon-based negative electrode electrolyte, characterized in that, Used in lithium-ion batteries.

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