Non-flammable safe electrolyte for high-voltage positive electrode / silicon-carbon negative electrode lithium ion battery and lithium ion battery

Abstract

This invention relates to a non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries and the lithium-ion battery itself. The electrolyte comprises a main solvent, a lithium salt, a flame retardant, and additives; the main solvent comprises fluoroethylene carbonate and linear carbonates or linear carboxylic acids. The lithium salt is lithium hexafluorophosphate. The flame retardant is (ethoxy)pentafluorocyclotriphosphazene. The concentration of the lithium salt in the electrolyte is 0.8–1.6 mol·L⁻¹. ‑1 The flame retardant has a mass percentage content of 1-10%, and each additive has a mass percentage content of 1-5%. The lithium-ion battery includes a positive electrode, a negative electrode, and a high-voltage positive electrode / silicon-carbon negative electrode. The lithium-ion battery uses a non-flammable and safe electrolyte. Compared with existing technologies, this invention has advantages such as being non-flammable, having good safety, high conductivity, good oxidation stability, compatibility with silicon-carbon negative electrodes, and promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries and the lithium-ion battery itself. Background Technology

[0002] Lithium-ion batteries are widely used in portable smart devices, new energy vehicles, and other fields due to their high energy density, excellent cycle performance, and lack of memory effect. However, with the ever-increasing demand for lithium battery energy, there is a need for lithium batteries to have higher energy density, shorter charging times, and higher safety. These are issues that urgently need to be addressed in the current development of lithium-ion batteries.

[0003] Using high-voltage, high-energy-density cathode materials and high-energy-density anode materials, such as silicon-carbon anodes, is an effective way to improve the energy density of lithium-ion batteries. Traditional carbonate electrolytes are insufficient for high-voltage cathodes, leading to continuous oxidation and decomposition of the electrolyte and rapid capacity decay. For silicon-carbon anodes, the SEI layer formed by traditional carbonate electrolytes cannot accommodate the larger lattice volume changes in silicon-carbon materials during lithium insertion / extraction, resulting in pulverization of the silicon-carbon anode material and further rapid degradation of battery performance. Furthermore, the flammability of traditional carbonate electrolytes poses a threat to current lithium-ion battery applications. To address these development needs, researching safe (non-flammable) electrolytes with high conductivity that are suitable for both high-voltage cathodes and silicon-carbon anodes is urgently needed.

[0004] Currently, there are few literature reports on non-flammable and safe electrolytes applicable to high-voltage positive / silicon-carbon negative lithium-ion batteries. The inventors learned that in ACS Appl Mater Interfaces, 12(20), 23035-23045(2020), an electrolyte constructed from piperidine bis(fluorosulfonyl)imide (PMpipFSI) ionic liquid was applied to a high-voltage NMC532 / silicon-carbon negative lithium-ion battery. Although ionic liquid electrolytes are non-volatile and non-flammable, the strong Coulomb forces between ions in ionic liquid electrolytes result in poor fluidity, high viscosity, and thus low conductivity. For example, the room temperature conductivity of a 5M LiFSI PMpipFSI electrolyte is only 0.353 mS / cm. -1 The viscosity at room temperature is as high as 936.6 cP. In the literature InfoMat, 2(5), 984-992 (2020), 0.8 M lithium salt LiPF6 was added to tris(2,2,2-trifluoroethyl) phosphate (TFEP) solvent, and then fluoroethylene carbonate (FEC) and vinylene carbonate (VC) were added to form an electrolyte. However, the lithium salt dissociation ability of TFEP solvent is poor, and the room temperature conductivity of its electrolyte is only 1.1 mS cm⁻¹. -1The room temperature conductivity of the safe electrolytes reported above is significantly lower than that of traditional carbonate electrolytes (~10 mS / cm). -1 This makes it difficult to meet the needs of actual applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a non-flammable, safe electrolyte and lithium-ion battery for high-voltage positive / silicon-carbon negative lithium-ion batteries that is non-flammable, safe, has high conductivity, good oxidation stability, is compatible with silicon-carbon negative electrodes, and has good application prospects.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] In this invention, fluoroethylene carbonate (FEC) and linear carbonate or linear carboxylic acid ester are used as a mixed solvent, and a highly efficient flame retardant (ethoxy) pentafluorocyclotriphosphazene (PFPN) and additives are added to construct a novel electrolyte with high conductivity and high safety (non-flammable) that can support the excellent performance of high-voltage positive / silicon-carbon negative lithium-ion batteries. The specific scheme is as follows:

[0008] A non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries, the electrolyte comprising a main solvent, lithium salt, flame retardant and additives; the main solvent comprising fluoroethylene carbonate (FEC) and linear carbonate or linear carboxylic acid ester.

[0009] Furthermore, the lithium salt is lithium hexafluorophosphate.

[0010] Furthermore, the flame retardant is (ethoxy)pentafluorocyclotriphosphazene (PFPN).

[0011] Further, the additives include one or more of 1,3-propenesulfonate lactone (PES), vinyl sulfate (DTD), methylene disulfonate (MMDS), 1,3-propanesulfonate lactone (PS), 3-cyclobutene sulfone (BSF), lithium difluorooxalate borate (LiODFB), lithium dioxalate borate (LiBOB), vinylene carbonate (VC), ethylene ethylene carbonate (VES), maleic anhydride (MA), or succinic anhydride (SA).

[0012] Furthermore, the linear carbonate includes dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate.

[0013] Furthermore, the linear carboxylic acid ester includes ethyl acetate, propyl acetate, or ethyl propionate.

[0014] Furthermore, the mass percentage of fluoroethylene carbonate in the main solvent is 30-90%, preferably 30-70%, and more preferably 40-70%.

[0015] Furthermore, the concentration of lithium salt in the electrolyte is 0.8-1.6 mol·L⁻¹. -1 .

[0016] Furthermore, in the electrolyte, the flame retardant has a mass percentage content of 1-10%, preferably 3-10%, and the mass percentage content of each additive is 1-5%.

[0017] A lithium-ion battery comprising a positive electrode, a negative electrode, and a non-flammable safe electrolyte for a high-voltage positive / silicon-carbon negative electrode lithium-ion battery as described above.

[0018] This invention uses FEC mixed with linear carbonates or linear carboxylic esters as the main solvent for LiPF6. The mixed solvent of FEC and linear carbonates or linear carboxylic esters has strong lithium salt dissociation ability, giving the electrolyte a high conductivity close to that of traditional carbonate electrolytes. Simultaneously, the FEC mixed solvent can form a stable and elastic SEI on the silicon-carbon anode; it meets the requirements of high-voltage cathode materials, preventing continuous oxidative decomposition reactions that could damage battery cycle performance. The flame retardant PFPN has high flame retardant ability, and its addition in small amounts makes the electrolyte completely non-flammable. Additives PES, DTD, MMDS, PS, BSF, LiODFB, LiBOB, VC, VES, MA, and SA can participate in the film formation process, making the formed SEI more stable and dense, thus meeting the cycle requirements of the electrolyte in high-voltage cathode / silicon-carbon anode lithium-ion batteries.

[0019] Compared to existing LiPF6-carbonate electrolyte systems, this electrolyte is suitable for high-voltage environments, compatible with silicon-carbon anodes, possesses high conductivity, and is completely non-flammable, ensuring lithium-ion battery safety. Experiments with this electrolyte in high-voltage lithium cobalt oxide cathode / silicon-carbon anode pouch cells showed that the cells exhibited good cycle performance and excellent rate performance. Attached Figure Description

[0020] Figure 1 The results are for safety tests of the electrolytes prepared in Comparative Examples 1-3, Examples 1, 14, and 25.

[0021] Figure 2 Cyclic performance curves at room temperature and 1C rate for the electrolytes prepared in Comparative Example 1 and Example 1 when applied to a silicon-carbon / cobalt oxide lithium pouch full battery system.

[0022] Figure 3 The electrolyte prepared in Example 1 was applied to a silicon-carbon / lithium cobalt oxide soft-pack full battery system, and the charge-discharge curves were obtained for the 50th, 100th, 150th and 200th cycles at room temperature and 1C rate.

[0023] Figure 4 Rate performance curves at 1C, 2C, 4C, 6C and 8C rates at room temperature were obtained for the application of the electrolytes prepared in Comparative Example 1 and Example 1 in a silicon-carbon / cobalt oxide lithium pouch full battery system.

[0024] Figure 5 The electrolyte prepared in Example 1 is used in a silicon-carbon / lithium cobalt oxide soft-pack full battery system, and the corresponding charge-discharge curves at room temperature and 1C, 2C, 4C, 6C and 8C rates are shown. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] A non-flammable and safe electrolyte for lithium-ion batteries is prepared by mixing one or more of the following as additives: fluoroethylene carbonate (FEC), linear carbonate or linear carboxylic acid ester as the main solvent, lithium hexafluorophosphate as the lithium salt, (ethoxy)pentafluorocyclotriphosphazene (PFPN) as the flame retardant, and 1,3-propenesulfonate lactone (PES), vinyl sulfate (DTD), methanedisulfonate methane (MMDS), 1,3-propanesulfonate lactone (PS), 3-cyclobutene sulfone (BSF), lithium difluorooxalate borate (LiODFB), lithium dioxalate borate (LiBOB), vinylene carbonate (VC), ethylene ethylene carbonate (VES), maleic anhydride (MA), and succinic anhydride (SA).

[0027] The main solvent contains 30-70% FEC by mass, with the remainder being one or more linear carbonates or linear carboxylic acid esters. The linear carbonates include dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate; the linear carboxylic acid esters include ethyl acetate, propyl acetate, and ethyl propionate. The flame retardant contains 1-10% (ethoxy)pentafluorocyclotriphosphazene by mass. The additives contain 1-5% (by mass) one or more of PES, DTD, MMDS, PS, BSF, LiODFB, LiBOB, VC, VES, MA, and SA. The electrolyte contains 0.8-1.6 mol / L of lithium hexafluorophosphate.

[0028] A lithium-ion battery includes: an electrolyte, a positive electrode, and a negative electrode. The positive and negative electrodes are commonly used in the art. The electrolyte is a non-flammable, high-voltage safe electrolyte for lithium-ion batteries. In actual preparation, an appropriate amount of FEC and an appropriate amount of linear carbonate or linear carboxylic acid ester are mixed evenly and added to a clean, dry reagent bottle as the solvent for the electrolyte. The mass percentage of FEC is 30-70%, and the mass percentage of linear carbonate or linear carboxylic acid ester is 30-70%. The above solvent mixture is added to an appropriate amount of lithium salt LiPF6 and stirred until fully dissolved. The concentration of the lithium salt is 0.8-1.6M. An appropriate amount of flame retardant PFPN is then added to the electrolyte. The mass percentage of PFPN is 1-10%, and one or more of the following additives are added at a mass percentage of 1-5%: PES, DTD, MMDS, PS, BSF, LiODFB, LiBOB, VC, VES, MA, and SA. The electrolyte is then stirred until fully mixed.

[0029] The safety and conductivity of the electrolyte of this invention, its fabrication properties in pouch cells, cycle performance, and rate performance were evaluated using the following methods:

[0030] 1. Electrolyte ignition experiment and conductivity test

[0031] The safety of the electrolyte was tested using an alcohol lamp ignition method. A 0.2g non-flammable cotton ball was placed on a clean petri dish, and then 1g of the mixed electrolyte was dropped onto the cotton ball. The fully soaked cotton ball was then placed over the outer flame of a lit alcohol lamp. If the cotton ball immediately ignited and continued to burn after the flame was removed, the electrolyte was defined as flammable and had poor safety. If the cotton ball did not ignite immediately upon approaching the flame, and did not continue to burn after 15 seconds, the electrolyte was defined as non-flammable and had good safety. The room temperature conductivity of the electrolyte was measured using a conductivity meter.

[0032] 2. Manufacturing of soft-pack batteries

[0033] The specific capacity of the graphite-silicon composite anode material is 420 mAh g. -1 The active material loading of the negative electrode is 6.7 mg / cm³. -2 The high-voltage cathode material is lithium cobalt oxide (LiCoO2), and the active material loading of the cathode electrode is 14.2 mg / cm³. -2 The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets, and wound to obtain a bare battery cell. The bare battery cell is placed in an aluminum-plastic film package, and the electrolyte is injected into the dried battery (the composition of the electrolyte is described in the specific implementation section). The battery is then allowed to stand at room temperature to complete the preparation of the lithium-ion soft-pack battery.

[0034] 3. Battery formation

[0035] High-voltage lithium cobalt oxide cathode / silicon-carbon anode pouch cells were formed at room temperature using battery testing equipment. After resting at room temperature, the pouch cells were charged to 4.45V under constant current and constant voltage at 0.1C, with a cutoff current of 0.05C for constant voltage charging. After resting for 10 minutes, they were discharged to 3.0V under constant current at 0.1C. This process was repeated twice under these conditions, and then the cells were degassed to complete the formation step.

[0036] 4. Battery cycle performance test

[0037] The high-voltage lithium cobalt oxide cathode / silicon-carbon anode pouch cells were subjected to cycle performance testing at room temperature using battery testing equipment. After formation, the cells were charged to 4.45V under constant current and constant voltage conditions at 1C, with a cutoff current of 0.05C for constant voltage charging. After resting for 10 minutes, the cells were discharged to 3.0V under constant current conditions at 1C, and this cycle was repeated until the set number of cycles was reached.

[0038] 5. Battery rate performance test

[0039] The rate performance of high-voltage lithium cobalt oxide cathode / silicon-carbon anode pouch cells was tested at room temperature using battery testing equipment. After formation, the battery is charged at a constant current and constant voltage (DCV) of 1C to 4.45V, with a DCV cutoff current of 0.05C. It is then left to rest for 10 minutes, followed by a constant current discharge at 1C to 3.0V, repeated 5 times. After another 10 minutes of rest, it is charged and discharged at a constant current and constant voltage (DCV) of 2C for 5 cycles, with a DCV cutoff current of 0.05C. After another 10 minutes of rest, it is charged and discharged at a constant current and constant voltage (DCV) of 4C for 5 cycles, with a DCV cutoff current of 0.05C. After another 10 minutes of rest, it is charged and discharged at a constant current and constant voltage (DCV) of 6C for 5 cycles, with a DCV cutoff current of 0.05C. After another 10 minutes of rest, it is charged and discharged at a constant current and constant voltage (DCV) of 8C for 5 cycles, with a DCV cutoff current of 0.05C. Finally, it is charged and discharged at a constant current and constant voltage (DCV) of 1C for 5 cycles, with a DCV cutoff current of 0.05C.

[0040] Comparative Example 1:

[0041] It is a traditional carbonate electrolyte with a composition of 1M LiPF6-EC / DMC (1:1, vol). The safety performance test, room temperature cycling test and room temperature rate test methods are as described above.

[0042] Comparative Example 2:

[0043] It is a traditional carbonate electrolyte with a composition of 1M LiPF6-EC / DEC (1:1, vol). The safety performance test, room temperature cycling test and room temperature rate test methods are as described above.

[0044] Comparative Example 3:

[0045] It is a traditional carbonate electrolyte with a composition of 1M LiPF6-EC / DMC / DEC (1:1:1, vol). The safety performance test, room temperature cycling test and room temperature rate test methods are as described above.

[0046] Comparative Example 4:

[0047] In an argon-filled glove box, 3% PFPN and 2% PES by weight were added to a conventional carbonate electrolyte [1M LiPF6-EC / DMC (1:1, vol)] and stirred until fully mixed to obtain the electrolyte for this comparative example. The ratio was 1M LiPF6-LiPF6-EC / DEC (1:1, vol) + 3wt% PFPN + 2wt% PES. The safety performance testing, room temperature cycling test, and room temperature rate test methods are as described above.

[0048] Comparative Example 5:

[0049] In an argon-filled glove box, weigh the required amount of LiPF6 to prepare an electrolyte with a lithium salt concentration of 1M. Weigh 60% FEC and 40% DMC by weight, mix them thoroughly, and then slowly add them to the LiPF6 while stirring until completely dissolved. Next, add 3% trimethyl phosphate (TMP) and 2% PES by weight to the electrolyte and stir until fully mixed. This yields the electrolyte for this comparative example, with a ratio of 1M LiPF6-FEC / DMC (60:40, wt) + 3wt% TMP + 2wt% PES. The safety performance tests, room temperature cycling tests, and room temperature rate testing methods are as described above.

[0050] Comparative Example 6:

[0051] In an argon-filled glove box, weigh the required amount of LiPF6 to prepare an electrolyte with a lithium salt concentration of 1M. Weigh 60% FEC and 40% DMC by weight, mix them thoroughly, and then slowly add them to the LiPF6 while stirring until completely dissolved. Next, add 40% trimethyl phosphate (TMP) and 2% PES by weight to the electrolyte and stir until fully mixed. This yields the electrolyte for this comparative example, with a ratio of 1M LiPF6-FEC / DMC (60:40, wt) + 40wt% TMP + 2wt% PES. The safety performance tests, room temperature cycling tests, and room temperature rate testing methods are as described above.

[0052] Comparative Example 7:

[0053] In an argon-filled glove box, weigh the required amount of LiPF6 to prepare a 1M lithium salt electrolyte. Weigh 60% FEC and 40% DMC by weight, mix them thoroughly, and then slowly add them to the LiPF6 while stirring until completely dissolved. Next, add 30% tris(2,2,2-trifluoroethyl phosphate) (TFEP) and 2% PES by weight to the electrolyte and stir until fully mixed. This yields the electrolyte for this comparative example, with a ratio of 1M LiPF6-FEC / DMC (60:40, wt) + 30wt% TFEP + 2wt% PES. The safety performance tests, room temperature cycling tests, and room temperature rate testing methods are as described above.

[0054] Comparative Example 8:

[0055] In an argon-filled glove box, weigh the required amount of LiPF6 to prepare a 1M lithium salt electrolyte. Weigh 60% FEC and 40% DMC by weight, mix them thoroughly, and then slowly add them to the LiPF6 while stirring until completely dissolved. Next, add 25% tri(2,2,2-trifluoroethyl phosphite) (TFEPi) and 2% PES by weight to the electrolyte and stir until fully mixed. This yields the electrolyte for this comparative example, with a ratio of 1M LiPF6-FEC / DMC (60:40, wt) + 25wt% TFEPi + 2wt% PES. The safety performance tests, room temperature cycling tests, and room temperature rate testing methods are as described above.

[0056] Example 1

[0057] In an argon-filled glove box, weigh the required amount of LiPF6 to prepare an electrolyte with a lithium salt concentration of 1M. Weigh 60% FEC and 40% DMC by weight, mix them thoroughly, and then slowly add them to the LiPF6 while stirring until completely dissolved. Next, add 3% PFPN and 2% PES by weight to the electrolyte and stir until fully mixed. This yields the safe electrolyte of this embodiment, with a ratio of 1M LiPF6-FEC / DMC (60:40, wt) + 3wt% PFPN + 2wt% PES. The safety performance testing, room temperature cycling test, and room temperature rate test methods are as described above.

[0058] In Examples 2 to 31, the electrolyte preparation method is the same as in Example 1. The electrolyte composition of the examples is shown in Table 1. The safety performance test, room temperature cycling test and room temperature rate test methods are as described above.

[0059] Table 1 shows the electrolyte composition of Comparative Examples 1-8 and Examples 1-31, as well as the safety test results of the corresponding electrolyte compositions.

[0060] Table 1

[0061]

[0062]

[0063] Table 2 shows the capacity retention rates of the electrolytes of Comparative Examples 1 to 8 after 100 or 200 cycles in lithium cobalt oxide / silicon-carbon anode pouch cells, and the capacity retention rates of the electrolytes of Examples 1 to 31 after 200 cycles in lithium cobalt oxide / silicon-carbon anode pouch cells.

[0064] Table 2

[0065]

[0066]

[0067]

[0068] As shown in Table 1, the three traditional carbonate electrolytes are highly flammable. Commonly used phosphate ester flame retardants (such as TMP, TFEP, and TFEPi) require a high dosage of at least 25 wt% to make the electrolyte non-flammable. However, in the examples, the dosage of PFPN, which has strong flame retardant capabilities, is no more than 10 wt% to make the electrolyte safe and non-flammable. Figure 1 The results showed that all three conventional carbonate electrolytes burned for a relatively long time, while the electrolytes of the three representative embodiments were non-flammable. Safety performance tests indicate that conventional carbonate electrolytes are highly flammable, posing a safety hazard to lithium-ion batteries; whereas the electrolytes of the embodiments of this invention are non-flammable, helping to improve battery safety.

[0069] As shown in Table 2, the discharge capacity of traditional carbonate electrolytes in lithium cobalt oxide / silicon-carbon anode lithium-ion batteries decreases rapidly. This is because traditional carbonate electrolytes cannot form a stable interface layer that meets the cycling conditions, leading to continuous electrolyte consumption and rapid capacity degradation. Batteries with non-flammable electrolytes containing high levels of phosphate ester flame retardants also exhibit poor cycle performance, indicating that high levels of phosphate ester flame retardants have a significant negative impact on battery performance. In contrast, the non-flammable electrolyte in the example exhibits good cycle performance in lithium cobalt oxide / silicon-carbon anode lithium-ion batteries. This is because the synergistic effect of FEC solvent and additives, along with the low amount of flame retardant in the example electrolyte, helps form a high-performance and stable interface layer at the electrode interface. This effectively prevents the continuous decomposition of the electrolyte during battery cycling and helps stabilize the silicon-carbon anode material structure, thus enabling the lithium cobalt oxide / silicon-carbon anode lithium-ion battery to possess good cycle performance. For example... Figure 2 , Figure 3In Comparative Example 1, the discharge capacity retention rate after 100 electrolyte cycles was only 35.65%, while in Example 1, the discharge capacity retention rate after 200 electrolyte cycles was 87.28%.

[0070] The electrolytes in the embodiments of this invention have strong solvent lithium salt dissociation ability, giving the electrolytes good room temperature conductivity, all within 8 mS / cm. -1 For example, the electrolyte in Example 1 [1M LiPF6-FEC / DMC (6:4, wt) + 3wt% PFPN + 2wt% PES] has a room temperature conductivity of 9.56 mS / cm. -1 These novel safe electrolytes exhibit room temperature conductivity close to that of conventional carbonates (~10 mS / cm). -1 This allows the battery to achieve ideal rate performance; such as Figure 4 , Figure 5 The results show that the high-voltage positive electrode / silicon-carbon negative electrode lithium-ion battery using the electrolyte of Example 1 has better capacity stability at a high rate of 8C than the battery using a conventional carbonate electrolyte.

[0071] In summary, this invention provides a novel safe (non-flammable) electrolyte suitable for high-voltage positive / silicon-carbon negative lithium-ion batteries. The battery exhibits both good cycle performance and ideal rate performance, thus showing great promise.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries, characterized in that, The electrolyte includes a main solvent, lithium salt, flame retardant, and additives; The lithium salt is lithium hexafluorophosphate; The flame retardant is (ethoxy)pentafluorocyclotriphosphazene; Fluorinated ethylene carbonate and linear carbonate or linear carboxylic acid ester are used as the main solvent, wherein the mass percentage of fluoroethylene carbonate in the main solvent is 30-70%; The concentration of lithium salt in the electrolyte is 0.8-1.6 mol·L⁻¹. -1 The electrolyte contains 1-10% flame retardant by mass. The main solvent can form a stable and elastic SEI in the silicon-carbon anode; it can meet the needs of high-voltage cathode materials and will not cause continuous oxidation decomposition reaction and damage the battery cycle performance.

2. The non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries according to claim 1, characterized in that, The additives include one or more of 1,3-propenesulfonate lactone, vinyl sulfate, methylene disulfonate, 1,3-propanesulfonate lactone, 3-cyclobutene sulfone, lithium difluorooxalate borate, lithium dioxalate borate, vinylene carbonate, ethylene ethylene carbonate, maleic anhydride, or succinic anhydride, with each additive accounting for 1-5% by mass.

3. The non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries according to claim 1, characterized in that, The linear carbonates mentioned include dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate.

4. The non-flammable and safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries according to claim 1, characterized in that, The linear carboxylic acid esters mentioned include ethyl acetate, propyl acetate, or ethyl propionate.

5. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, and a non-flammable safe electrolyte for high-voltage positive / silicon-carbon negative lithium-ion batteries as described in any one of claims 1-4.

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