A lithium battery electrolyte and lithium ion battery

Abstract

The present application relates to a lithium battery electrolyte and a lithium ion battery. The lithium battery electrolyte comprises a phosphine-containing additive having the following general formula I, R1, R2, R3, R4 are independently selected from any one of substituted or unsubstituted alkyl, alkyl acyl, alkynyl, alkenyl, cycloalkyl, aromatic group. The phosphine-containing additive will undergo oxidation polymerization or reduction polymerization on the positive or negative electrode when in the electrolyte, forming a dense surface film with high ionic conductivity on the surface of the positive or negative electrode, which has a certain ion permeability and can isolate the electrolyte from the positive electrode with strong oxidation (or the negative electrode with strong reduction), without deteriorating the interface impedance and reducing the solvent in the electrolyte and the side reaction of the electrode at high temperature. Formula I

Description

Technical Field

[0001] This article relates to lithium-ion battery technology, and more particularly to a lithium battery electrolyte and a lithium-ion battery. Background Technology

[0002] With the advancement of lithium battery technology, the requirements for energy density are becoming increasingly stringent. The positive electrode often adopts a high-nickel system of Ni8 series or above. However, the high-nickel system will generate singlet oxygen with high oxidation activity during the lithium insertion and extraction process, which will oxidize the electrolyte and cause a large amount of gas production. The negative electrode often adopts Si / Gr composite. The silicon particles break down during the cycling process, which leads to the reconstruction of the SEI film and the accelerated consumption of electrolyte and gas production.

[0003] Currently, there are many types of additives that can suppress gas production, such as sulfur-based additives like PS and PST, borate ester additives like TMSB and TEB, as well as nitrile and phosphite additives; however, the disadvantages of the above additives are that they will significantly worsen the interfacial impedance, such as PS and nitrile additives, and will also worsen the cycle performance. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0005] The first aspect of this application provides a lithium battery electrolyte, including a phosphine-containing additive, said phosphine-containing additive being a compound having the general formula (I). I.

[0006] In one exemplary embodiment, in the phosphine-containing additive, R1, R2, R3, and R4 are each independently selected from any one of substituted or unsubstituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups.

[0007] In one exemplary embodiment, when R1, R2, R3, and R4 are each independently selected from any one of substituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups, the substituent is at least one of halogen (e.g., fluoroalkyl), cyano, and isocyanate groups.

[0008] In one exemplary embodiment, the alkyl group is a C1-C6 straight-chain or branched alkyl group; the alkyl acyl group is a C1-C6 alkyl acyl group (e.g., formyl, acetyl, etc.); the alkynyl group is a C2-C4 alkynyl group; the alkenyl group is a C2-C4 alkenyl group; the cycloalkyl group is a C3-C6 cycloalkyl group; and the aromatic group is a C6-C6 cycloalkyl group. 18 aryl or C5-C 18 Mixed aromatic compounds.

[0009] In one exemplary embodiment, the phosphine-containing additive is selected from at least one of the following compounds: 1,2-Bis(diphenylphosphine)ethane, 1,2-Bis(dicyclohexylphosphino)-ethane, 1,2-bis(dimethylphosphine)ethane, 1,2-Bis(diethylphosphine)ethane, 1,2-Bis(di-tert-butylphosphine)ethane, 1,2-bis(di-2-pyridylphosphine)ethane, 1,2-Bis(diisopropylphosphino)ethane.

[0010] In one exemplary embodiment, the phosphine-containing additive has a mass fraction of 0.05%-1.5% in the lithium battery electrolyte; Preferably, it is 0.1% to 1%; More preferably, it is 0.1% to 0.5%.

[0011] In one exemplary embodiment, the lithium battery electrolyte further includes other additives, solvents, and lithium salts.

[0012] In one exemplary embodiment, the other additives have a mass fraction of 0.5%-15% in the lithium battery electrolyte; preferably, it is 2%-10%.

[0013] In one exemplary embodiment, the other additives are selected from one or more of the following: fluoroethylene carbonate (FEC), lithium tetrafluoroborate (LiBF4), tris(trimethylsilane)borate (TMSB), isocyanate (HDI), hexanetrionitrile (HTCN), vinylene carbonate (VC), vinyl sulfate (DTD), tris(trimethylsilane) phosphate (TMSP), triargyl phosphate (TPP), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), lithium difluorodioxalate phosphate (ODFP), methane disulfonate methane (MMDS), and 1,3-propane sulfonate lactone (PS). Optionally, the other additives are vinylene carbonate, fluoroethylene carbonate, 1,3-propanesulfonate lactone, and lithium difluorodioxazophosphate.

[0014] In one exemplary embodiment, among the other additives, the mass fraction of vinylene carbonate in the lithium battery electrolyte is 0.1%-0.8%, the mass fraction of fluoroethylene carbonate in the lithium battery electrolyte is 2%-10%, the mass fraction of 1,3-propanesulfonate lactone in the lithium battery electrolyte is 0.3%-1.5%, and the mass fraction of lithium difluorodioxalate phosphate in the lithium battery electrolyte is 0.3%-1%. Preferably, the mass fraction of vinylene carbonate in the lithium battery electrolyte is 0.5%, the mass fraction of fluoroethylene carbonate in the lithium battery electrolyte is 5%, the mass fraction of 1,3-propanesulfonyl lactone in the lithium battery electrolyte is 0.5%, and the mass fraction of lithium difluorodioxarate phosphate in the lithium battery electrolyte is 0.8%.

[0015] In one exemplary embodiment, the solvent is selected from one or both of carbonates and carboxylic esters; Optionally, the solvent is selected from at least three of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, propyl acetate, and ethyl propionate.

[0016] In one exemplary embodiment, the solvent is ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate in a mass ratio of (15-25):(5-15):(65-75); Preferably, the mass ratio of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 20:10:70.

[0017] In one exemplary embodiment, the lithium salt is selected from at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; Optionally, the lithium salt is lithium hexafluorophosphate and lithium difluorosulfonylimide in a mass ratio of (4-10):(0-6); Preferably, the mass ratio of lithium hexafluorophosphate to lithium difluorosulfonylimide is 7:3.

[0018] In one exemplary embodiment, the molar concentration of the lithium salt in the lithium battery electrolyte is from 0.5 mol / L to 2 mol / L, preferably 1-1.5 mol / L.

[0019] A second aspect of this application provides a lithium-ion battery, including the aforementioned lithium battery electrolyte, separator, negative electrode, and positive electrode, wherein the separator is located between the positive electrode and the negative electrode.

[0020] In one exemplary embodiment, the negative electrode is a silicon negative electrode, and the active material in the silicon negative electrode includes silicon material.

[0021] In one exemplary embodiment, the silicon material in the silicon anode is selected from at least one of nano-elemental silicon, silicon suboxide, silicon carbide, and silicon-based alloys.

[0022] In one exemplary embodiment, the silicon material accounts for 5%-15% of the mass fraction of the active material in the silicon anode; Preferably, it is 10%.

[0023] Compared with existing related technologies, this application has the following technical effects: This application provides an electrolyte solution containing a phosphine-containing additive of Formula I, which can suppress cell gas generation, improve high-temperature cycling and storage capabilities, and does not deteriorate interfacial impedance. The phosphine-containing additive undergoes oxidative polymerization or reduction polymerization reactions on the positive and negative electrodes in the electrolyte, forming a dense surface film with high ionic conductivity on the surface of the positive and negative electrodes. This surface film has a certain ion permeability while isolating the electrolyte from the positive electrode with strong oxidizing properties (or the negative electrode with strong reducing properties), thus reducing the side reactions of the solvent in the electrolyte with the electrode at high temperatures without deteriorating the interfacial impedance.

[0024] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application may be realized and obtained by means of the methods described in the description. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0026] This application provides a lithium battery electrolyte, including a phosphine-containing additive, wherein the phosphine-containing additive is a compound having the general formula (I). I.

[0027] In the embodiments of this application, in the phosphine-containing additive, R1, R2, R3, and R4 are each independently selected from any one of substituted or unsubstituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups.

[0028] In the embodiments of this application, when R1, R2, R3, and R4 are each independently selected from any one of substituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups, the substituent is at least one of halogen (e.g., fluoroalkyl), cyano, and isocyanate groups.

[0029] In the embodiments of this application, the alkyl group is a C1-C6 straight-chain or branched alkyl group; the alkyl acyl group is a C1-C6 alkyl acyl group (e.g., formyl, acetyl, etc.); the alkynyl group is a C2-C4 alkynyl group; the alkenyl group is a C2-C4 alkenyl group; the cycloalkyl group is a C3-C6 cycloalkyl group; and the aromatic group is a C6-C4 cycloalkyl group. 18 aryl or C5-C 18 Mixed aromatic compounds.

[0030] In the embodiments of this application, the phosphine-containing additive is selected from at least one of the following compounds: 1,2-Bis(diphenylphosphine)ethane, 1,2-Bis(dicyclohexylphosphino)-ethane, 1,2-bis(dimethylphosphine)ethane, 1,2-Bis(diethylphosphine)ethane, 1,2-Bis(di-tert-butylphosphine)ethane, 1,2-bis(di-2-pyridylphosphine)ethane, 1,2-Bis(diisopropylphosphino)ethane.

[0031] In the embodiments of this application, the mass fraction of the phosphine-containing additive in the lithium battery electrolyte is 0.05%-1.5%, for example: 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable. Preferably, it is 0.1% to 1%; More preferably, it is 0.1% to 0.5%.

[0032] In the embodiments of this application, the lithium battery electrolyte also includes other additives, solvents, and lithium salts.

[0033] In the embodiments of this application, the other additives in the lithium battery electrolyte have a mass fraction of 0.5%-15%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, but are not limited to the listed values. Other unlisted values ​​within the above range are also applicable. Preferably, it is 2%-10%.

[0034] In the embodiments of this application, the other additives are selected from one or more of the following: fluoroethylene carbonate (FEC), lithium tetrafluoroborate (LiBF4), tris(trimethylsilane)borate (TMSB), isocyanate (HDI), hexanetrionitrile (HTCN), vinylene carbonate (VC), vinyl sulfate (DTD), tris(trimethylsilane) phosphate (TMSP), triargyl phosphate (TPP), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), lithium difluorodioxalate phosphate (ODFP), methylene disulfonate (MMDS), and 1,3-propanesulfonate lactone (PS). Optionally, the other additives are vinylene carbonate, fluoroethylene carbonate, 1,3-propanesulfonate lactone, and lithium difluorodioxazophosphate.

[0035] In the embodiments of this application, among the other additives, the mass fraction of vinylene carbonate in the lithium battery electrolyte is 0.1%-0.8%, the mass fraction of fluoroethylene carbonate in the lithium battery electrolyte is 2%-10%, the mass fraction of 1,3-propanesulfonate lactone in the lithium battery electrolyte is 0.3%-1.5%, and the mass fraction of lithium difluorodioxalate phosphate in the lithium battery electrolyte is 0.3%-1%; for example, the mass fraction of vinylene carbonate in the lithium battery electrolyte is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%. The mass fractions of fluoroethylene carbonate in the lithium battery electrolyte are 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%; the mass fractions of 1,3-propanesulfonyl lactone in the lithium battery electrolyte are 0.3%, 0.6%, 0.9%, 1.2%, and 1.5%; the mass fractions of lithium difluorodioxalate phosphate in the lithium battery electrolyte are 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%, but are not limited to the listed values. Other unlisted values ​​within the above range also apply. Preferably, the mass fraction of vinylene carbonate in the lithium battery electrolyte is 0.5%, the mass fraction of fluoroethylene carbonate in the lithium battery electrolyte is 5%, the mass fraction of 1,3-propanesulfonyl lactone in the lithium battery electrolyte is 0.5%, and the mass fraction of lithium difluorodioxarate phosphate in the lithium battery electrolyte is 0.8%.

[0036] In the embodiments of this application, the solvent is selected from one or two of carbonates and carboxylic acid esters; Optionally, the solvent is selected from at least three of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, propyl acetate, and ethyl propionate.

[0037] In the embodiments of this application, the solvent is ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate in a mass ratio of (15-25):(5-15):(65-75); Preferably, the mass ratio of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 20:10:70.

[0038] In the embodiments of this application, the lithium salt is selected from at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; Optionally, the lithium salt is lithium hexafluorophosphate and lithium difluorosulfonylimide in a mass ratio of (4-10):(0-6); Preferably, the mass ratio of lithium hexafluorophosphate to lithium difluorosulfonylimide is 7:3.

[0039] In the embodiments of this application, the molar concentration of the lithium salt in the lithium battery electrolyte is from 0.5 mol / L to 2 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable. Preferably, the concentration is 1-1.5 mol / L.

[0040] This application also provides a lithium-ion battery, including the above-mentioned lithium battery electrolyte, separator, negative electrode, and positive electrode, wherein the separator is located between the positive electrode and the negative electrode.

[0041] In this embodiment of the application, the negative electrode is a silicon negative electrode, and the active material in the silicon negative electrode includes silicon material.

[0042] In this embodiment, the silicon material in the silicon anode is selected from at least one of nano-elemental silicon, silicon suboxide, silicon carbide, and silicon-based alloys; Optionally, the silicon material accounts for 5%-15% of the mass fraction of the active material in the silicon anode; for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable. Preferably, it is 10%.

[0043] The present application will be further described in detail below with reference to specific embodiments, but these embodiments should not be construed as limiting the present application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this invention.

[0044] The raw materials used in this application are all conventional products on the market.

[0045] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0046] Experimental methods not specified in the examples are generally performed under standard conditions or as recommended by the manufacturer.

[0047] Example 1 This embodiment provides a lithium-ion secondary battery, comprising: Positive electrode: The positive electrode active material NCM811 (i.e., LiNi) 0.8 Co 0.1 Mn 0.1 O2), conductive agent SP and binder PVDF are mixed in a mass ratio of 97:2:1, NMP is added and stirred under vacuum to obtain positive electrode slurry. The positive electrode slurry is coated on positive electrode current collector aluminum foil, and then dried and cold pressed to obtain positive electrode sheet. Negative electrode sheet: Silicon material, artificial graphite, conductive agent SP, thickener CMC and binder SBR are mixed in a mass ratio of 9.6:86.6:1.2:1.2:1.4 (the mass of silicon material accounts for 10.0% of the total active material mass), deionized water is added, and the mixture is stirred under vacuum to obtain a negative electrode slurry. The negative electrode slurry is coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained after drying and cold pressing. Electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 20:10:70 to obtain an organic solvent. LiPF6 and LiFSI were then added to this organic solvent and dispersed, with a mass ratio of LiPF6:LiFSI = 70:30. Subsequently, vinylene carbonate, fluoroethylene carbonate, 1,3-propanesulfonate lactone, lithium difluorodioxanol phosphate, and 1,2-bis(diphenylphosphine)ethane were added and dispersed to obtain the electrolyte. The electrolyte contained 0.2% vinylene carbonate, 5% fluoroethylene carbonate, 1,3-propanesulfonate lactone, 0.5% lithium difluorodioxanol phosphate, and 0.2% 1,2-bis(diphenylphosphine)ethane. The total concentration of LiPF6 and LiFSI was 1.2 mol / L. The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes. After winding, a battery cell is obtained and encapsulated with an aluminum-plastic film. After drying, electrolyte is injected, and the battery undergoes standing, formation, aging, sealing and welding, and capacity testing to obtain a secondary battery.

[0048] Example 2: The difference from Example 1 is that 1,2-bis(dicyclohexylphosphino)-ethane is used instead of 1,2-bis(diphenylphosphino)-ethane, wherein the content of 1,2-bis(dicyclohexylphosphino)-ethane is 0.2%.

[0049] Example 3: The difference from Example 1 is that 1,2-bis(diisopropylphosphino)ethane is used instead of 1,2-bis(diphenylphosphino)ethane, wherein the content of 1,2-bis(diisopropylphosphino)ethane is 0.2%.

[0050] Comparative Example 1: The difference from Example 1 is that the electrolyte does not contain 1,2-bis(diphenylphosphine)ethane.

[0051] Comparative Example 2: The difference from Example 1 is that 0.2% TPP is used instead of 0.2% 1,2-bis(diphenylphosphine)ethane.

[0052] Comparative Example 3: The difference from Example 1 is that the content of 1,2-bis(diphenylphosphine)ethane is 2%.

[0053] Performance testing: 1. 45℃ Cycling Performance Test: At 45℃, the battery is subjected to charge-discharge cycle tests at a 1C / 1C charge-discharge rate within the range of 2.75-4.25V. The discharge specific capacity of the battery in the first cycle and the discharge specific capacity after 500 cycles are recorded. The capacity retention rate after 500 cycles is calculated as follows: Capacity retention rate after 500 cycles = Discharge specific capacity after 500 cycles / Discharge specific capacity in the first cycle. 100%.

[0054] 2. Initial DCR Test: At 25℃, allow the device to stand for 10 minutes, charge at 1C to 4.25V, allow it to stand for 10 minutes, discharge at 0.33C for 90 minutes, adjust to 50% SOC, allow it to stand for 30 minutes, and then perform a 2C constant current pulse discharge for 10 seconds. Calculate the DCR: DCR (mΩ) = (Voltage before pulse discharge - Voltage after pulse discharge) / Discharge current 1000.

[0055] 3. High-Temperature Storage Capacity Test: Place the battery at 60℃ for 120 minutes, then perform a charge-discharge test at a 1C / 1C charge-discharge rate within the range of 2.75-4.25V, and record the discharge specific capacity of the battery in the first week. Afterward, store the battery at 60℃ for 150 days, and repeat the charge-discharge test using the same method, recording the discharge specific capacity again. Calculate the high-temperature storage capacity retention rate: High-temperature storage capacity retention rate = Discharge specific capacity after 150 days of high-temperature storage / Discharge specific capacity in the first week. 100%.

[0056] The lithium-ion secondary batteries obtained in each embodiment and comparative example were tested for DCR at 25°C, cycle performance at 45°C, and storage performance at 60°C. The test voltage range was 2.75V-4.25V. The test results are shown in Table 1.

[0057] Table 1 Electrochemical performance evaluation: According to Example 1 and Comparative Example 1, the addition of 1,2-bis(diphenylphosphine)ethane significantly suppressed gas production and significantly improved high-temperature cycling and storage capabilities. According to Comparative Example 1 and Comparative Example 3, the content of phosphine-containing additives should not be too high, otherwise it will cause a sharp increase in impedance and deteriorate cycling and storage. However, its ability to suppress gas production is still improved. Based on the overall judgment, it is necessary to control its dosage at an appropriate level.

[0058] As can be seen from Examples 1, 2, 3 and Comparative Example 1, different types of phosphine-containing additives have similar abilities to suppress gas production and improve circulation and storage. This is mainly because these phosphine-containing additives can participate in the formation of the positive electrode film, forming a dense surface film with high electronic conductivity. This surface film has a certain ion permeability while isolating the electrolyte from the positive electrode with strong oxidizing properties (or the negative electrode with strong reducing properties). It does not deteriorate the interfacial impedance while reducing the side reactions between the solvent in the electrolyte and the electrode at high temperatures. It can also complex transition metal ions, reducing the catalytic decomposition of the electrolyte.

[0059] As can be seen from Example 1 and Comparative Example 2, compared with TPP, the phosphine-containing additive of this application can take into account film resistance and has better overall performance.

[0060] In summary, this application provides an electrolyte solution containing a phosphine-containing additive of Formula I, which can suppress cell gas generation, improve high-temperature cycling and storage capabilities, and does not deteriorate interfacial impedance. The phosphine-containing additive undergoes oxidative polymerization or reduction polymerization reactions on the positive or negative electrode in the electrolyte, forming a dense surface film with high ionic conductivity on the surface of the positive or negative electrode. This surface film has a certain ion permeability while isolating the electrolyte from the strongly oxidizing positive electrode (or the strongly reducing negative electrode), thus reducing the side reactions of the solvent in the electrolyte with the electrode at high temperatures without deteriorating the interfacial impedance.

[0061] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A lithium battery electrolyte comprising a phosphine-containing additive, said phosphine-containing additive being a compound having the general formula (I). （I）， R1, R2, R3, and R4 are each independently selected from any one of substituted or unsubstituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups; The phosphine-containing additive has a mass fraction of 0.05%-1.5% in the lithium battery electrolyte.

2. The lithium battery electrolyte according to claim 1, wherein, The alkyl group is a C1-C6 straight-chain or branched alkyl group; the alkyl acyl group is a C1-C6 alkyl acyl group; the alkynyl group is a C2-C4 alkynyl group; the alkenyl group is a C2-C4 alkenyl group; the cycloalkyl group is a C3-C6 cycloalkyl group; the aromatic group is a C6-C6 cycloalkyl group. 18 aryl or C5-C 18 Mixed aromatic compounds.

3. The lithium battery electrolyte according to claim 1 or 2, wherein, When R1, R2, R3, and R4 are each independently selected from any one of substituted alkyl, alkylacyl, alkynyl, alkenyl, cycloalkyl, and aromatic groups, the substituent is at least one of halogen, cyano, and isocyanate groups.

4. The lithium battery electrolyte according to claim 1 or 2, wherein, The phosphine-containing additive is selected from at least one of the following compounds: ， ， ， ， ， ， 。 5. The lithium battery electrolyte according to claim 1 or 2, wherein, The lithium battery electrolyte also includes other additives, solvents, and lithium salts.

6. The lithium battery electrolyte according to claim 5, wherein, The other additives are selected from one or more of the following: fluoroethylene carbonate, lithium tetrafluoroborate, tris(trimethylsilane)borate, isocyanate, hexanetrionitrile, vinylene carbonate, vinyl sulfate, tris(trimethylsilane) phosphate, triargyl phosphate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium difluorodioxalate phosphate, methanedisulfonate, and 1,3-propanesulfonate lactone; and / or The solvent is selected from one or two of carbonates and carboxylic acid esters; and / or The lithium salt is selected from at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

7. The lithium battery electrolyte according to claim 6, wherein, The other additives are vinylene carbonate, fluoroethylene carbonate, 1,3-propanesulfonate lactone, and lithium difluorodioxanol phosphate; and / or The solvent is selected from at least three of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, propyl acetate, and ethyl propionate; and / or The lithium salt is selected from at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

8. A lithium-ion battery, comprising a lithium battery electrolyte, a separator, a negative electrode, and a positive electrode as described in any one of claims 1 to 7, wherein the separator is located between the positive electrode and the negative electrode.

9. The lithium-ion battery according to claim 8, wherein, The negative electrode is a silicon negative electrode.

10. The lithium-ion battery according to claim 9, wherein, The silicon material in the silicon anode is selected from at least one of nano-elemental silicon, silicon suboxide, silicon carbide, and silicon-based alloys.

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