An electrolyte additive and an electrolyte containing the additive, and a lithium battery.

Abstract

This application specifically discloses an electrolyte additive, an electrolyte containing the additive, and a lithium battery. The electrolyte additive has the following structural formula: The electrolyte additive of this application can promote uniform film formation at the positive and negative electrodes; the B in the electrolyte additive can reduce the LiF content in the electrolyte, reduce the impedance between the electrode interfaces, thereby improving the high-temperature and high-voltage resistance of the lithium battery.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to an electrolyte additive and an electrolyte containing the additive, and a lithium battery. Background Technology

[0002] With continuous technological advancements and increasing demand for clean energy, lithium-ion batteries, as efficient and environmentally friendly energy storage devices, are gradually becoming an important component of the future energy sector. Driven by the expanding electric vehicle market and the development of renewable energy, lithium-ion battery technology is also evolving in response to human needs. Currently, the requirements for the energy density and safety performance of lithium-ion batteries are becoming increasingly stringent; therefore, improving the energy density of lithium batteries is a research hotspot in the field.

[0003] Currently, using high-voltage cathode materials is the primary method for improving the energy density of lithium-ion batteries. Therefore, high-voltage cathode materials such as LNMO, high-voltage ternary cathodes, high-voltage lithium cobalt oxide, and layered lithium-rich oxide (LLO) have become research hotspots. However, as the voltage of lithium-ion batteries continues to increase, the cathode material will have a higher electrode potential. At this point, the oxidation and decomposition of the electrolyte at the cathode and the reactions at the cathode interface will be more intense. With continuous charge-discharge cycles, the internal resistance of the lithium battery gradually increases, leading to a decline in battery performance or even failure.

[0004] To address this, existing technologies primarily employ two methods to improve the high-voltage resistance of electrolytes: one is to increase the lithium salt concentration in carbonate electrolytes; the other is to replace conventional carbonate solvents with sulfone solvents, nitrile solvents, ionic liquids, and fluorinated electrolytes. However, both methods have been found to have limitations in practice. Increasing the lithium salt concentration in the electrolyte increases production costs, hindering large-scale industrial applications. Sulfone solvents and ionic liquids have high melting points, which reduces the low-temperature performance of lithium batteries. Furthermore, the poor compatibility of nitrile solvents with graphite anodes limits the practical application of high-voltage electrolytes. Summary of the Invention

[0005] In order to address the problems and shortcomings of the prior art, this application provides an electrolyte additive and an electrolyte and lithium battery containing the additive.

[0006] In a first aspect, this application provides an electrolyte additive, which adopts the following technical solution:

[0007] An electrolyte additive, the structural formula of which is as follows:

[0008]

[0009] First, the electrolyte additive of this application promotes uniform film formation at the positive and negative electrode interfaces, helping to generate uniform and dense CEI and SEI films at the interfaces. This inhibits the dissolution of TMs (transition metal sulfides) ions and the release of oxygen, thereby suppressing the reduction of TMs ions at the negative electrode. This reduces the degree of interfacial reaction at the positive and negative electrodes, preventing an increase in internal resistance during lithium battery cycling and significantly improving the cycle performance of the lithium battery. Second, LiF in the electrolyte forms a LiF layer covering the electrode surface. As an insulating layer, the LiF layer hinders the effective transport of lithium ions and electrons between the electrodes. The B in the electrolyte additive of this application, acting as an anion acceptor, dissolves LiF in the electrolyte, reducing the LiF content and preventing the formation of a LiF layer on the electrode surface. This provides a better propagation path for lithium ion and electron conduction between the electrodes, thereby reducing the interfacial impedance. This not only helps improve the high-voltage cycle performance of lithium-ion batteries but also improves their thermal stability and high-temperature cycle performance.

[0010] Secondly, this application provides an electrolyte, which adopts the following technical solution:

[0011] An electrolyte comprising an organic solvent, a carbonate additive, a lithium salt, a lithium salt additive, and an electrolyte additive as described above.

[0012] Preferably, the electrolyte additive accounts for 0.3%-1% of the mass of the electrolyte.

[0013] When the mass percentage of electrolyte additives in the electrolyte is too low, it affects the density and thickness uniformity of the CEI and SEI films formed at the positive and negative electrode interfaces. Furthermore, due to the small amount of additives used, their synergistic effect with other components in the electrolyte is not significant, which is detrimental to their intended function. Conversely, when the mass percentage of electrolyte additives in the electrolyte is too high, it reduces the overall stability of the electrolyte. Additionally, it leads to more vigorous interfacial reactions at the positive and negative electrode interfaces, resulting in thicker CEI and SEI films. This can significantly increase the internal resistance of the lithium battery, thereby reducing its cycle performance.

[0014] Preferably, the electrolyte further includes a sulfur-containing additive, which includes at least one of propylene-1,3-propanesulfonate lactone (PST), 1,3-propanesulfonate lactone (PS), and vinyl sulfate (DTD); the sulfur-containing additive accounts for 0.5%-3% of the mass of the electrolyte.

[0015] Preferably, the sulfur-containing additive includes the propylene-1,3-propanesulfonate lactone PST and the 1,3-propanesulfonate lactone PS;

[0016] Alternatively, the sulfur-containing additive may include the propylene-1,3-propanesulfonate lactone (PST) and the vinyl sulfate (DTD).

[0017] Alternatively, the sulfur-containing additive may include the 1,3-propanesulfonate lactone (PS) and the vinyl sulfate (DTD).

[0018] Alternatively, the sulfur-containing additive may include propylene-1,3-propanesulfonate lactone PST, 1,3-propanesulfonate lactone PS, and vinyl sulfate DTD.

[0019] The electrolyte additive in this application can work in conjunction with sulfur-containing additives to improve the quality of film formation at the positive electrode and significantly enhance the stability of the electrolyte. Especially under high temperature and high pressure conditions, it can significantly suppress gas generation in lithium batteries and improve electrolyte wettability, thereby contributing to improved lithium battery cycle performance. When the mass percentage of sulfur-containing additives in the electrolyte is too low, it is not conducive to the formation of a uniform and stable CEI film at the positive electrode, and the electrolyte exhibits poor stability under high temperature and high pressure environments. Conversely, when the mass percentage of sulfur-containing additives in the electrolyte is too high, excessive film formation at the positive electrode reduces the wettability of the CEI film and increases the internal resistance of the lithium battery, both of which are detrimental to improving lithium battery cycle performance.

[0020] Preferably, the carbonate additive includes at least one of vinylene carbonate (VC) and fluoroethylene carbonate (FEC); the carbonate additive accounts for 0.01%-1% of the mass of the electrolyte.

[0021] The electrolyte additives in this application can work in conjunction with carbonate additives to help generate a uniform and stable SEI film at the negative electrode interface, thereby improving the stability of the lithium battery. Furthermore, the presence of carbonate additives can also improve the physicochemical properties of the electrolyte, enhance its ion conductivity and stability, all of which contribute to improving the high-temperature cycle performance of the lithium battery. When the mass percentage of carbonate additives in the electrolyte is too low, it will hinder uniform film formation at the negative electrode interface and reduce the electrochemical stability of the electrolyte to some extent, resulting in a decline in the cycle performance of the lithium-ion battery. When the mass percentage of carbonate additives in the electrolyte is too high, it will lead to excessive film thickness at the negative electrode, increasing the migration path of ions in the negative electrode film, resulting in low concentration polarization discharge capacity, which in turn affects the utilization rate of the battery's active materials. Furthermore, excessive film thickness at the negative electrode will lead to higher resistance in the lithium battery, making it prone to gas generation under high pressure and high temperature during cycling, damaging the structure of the lithium battery. In severe cases, it may even cause increased internal pressure, leakage, and battery expansion, seriously affecting the cycle performance and safety performance of the lithium battery.

[0022] Preferably, the organic solvent includes cyclic carbonates, chain carbonates, and chain carboxylic acid esters; the organic solvent accounts for 80%-90% of the mass of the electrolyte.

[0023] Preferably, in the organic solvent, the mass ratio of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester is 1-15:20-70:5-20.

[0024] By using the above three organic solvents, the stability of the electrolyte system can be improved, and the sulfur-containing additives and the electrolyte additives used in this application can exert a highly efficient synergistic effect. This also helps to improve the cycle performance of lithium-ion batteries in high temperature and high pressure environments.

[0025] Preferably, the lithium salt additive includes at least one of lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiBOB), and lithium difluorodi(oxalato)phosphate (LiDFOP); the lithium salt additive accounts for 0.5%-1% of the mass of the electrolyte.

[0026] Preferably, the lithium salt comprises lithium hexafluorophosphate (LiPF6); the lithium salt accounts for 10%-15% of the mass of the electrolyte.

[0027] By doping the electrolyte with appropriate types of lithium salt additives, the dissolution of metal ions at the positive and negative electrodes can be suppressed, reducing the destructive effect of metal ion dissolution on the CEI and SEI films and improving their stability. Furthermore, it can also compensate for the loss of active lithium during the cycling process of lithium-ion batteries, all of which contribute to improving the cycle performance of lithium-ion batteries.

[0028] Thirdly, this application provides a lithium battery, which adopts the following technical solution:

[0029] A lithium battery comprising the electrolyte as described above. Detailed Implementation

[0030] To better understand and implement this application, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only some of the embodiments of this application, and not all of them.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0032] Unless otherwise stated, all numerical values ​​for the amounts of expressed components, reaction conditions, etc., used in the specification and claims are to be understood as being modified by the term "about". Therefore, unless otherwise indicated, the numerical parameters set forth herein are approximate values ​​that can be varied to obtain the desired performance.

[0033] The word “and / or” as used in this article refers to one or all of the elements mentioned.

[0034] The terms "include" and "contain" as used in this article cover both cases where only the mentioned elements exist and cases where other unmentioned elements exist in addition to the mentioned elements.

[0035] All percentages in this application are weight percentages unless otherwise stated.

[0036] Unless otherwise stated, the terms “a,” “an,” “an,” and “the” as used in this specification are intended to include “at least one” or “one or more.” For example, “a component” refers to one or more components, and therefore more than one component may be considered and may be employed or used in the implementation of the described embodiments.

[0037] The electrolyte additives with the following structural formulas used in the following examples and comparative examples The CAS number is 865869-27-8.

[0038] Example 1

[0039] 1. Electrolyte and its preparation

[0040] The electrolyte in this embodiment includes an organic solvent, carbonate additives, lithium salt, lithium salt additives, electrolyte additives, and sulfur-containing additives in a mass ratio of 81.5%:0.5%:15%:0.5%:0.5%:2%.

[0041] The organic solvent consists of cyclic carbonates (fluoroethylene carbonate FEC and ethylene carbonate EC in a 1:1 mass ratio), chain carbonates (diethyl carbonate DEC), and chain carboxylic acid esters (ethyl difluoroacetate DFAE) in a mass ratio of 10:70:20.

[0042] The carbonate additive is vinylene carbonate (VC).

[0043] The lithium salt is lithium hexafluorophosphate (LiPF6).

[0044] The lithium salt additive is lithium difluorophosphate (LiPO2F2).

[0045] Electrolyte additive (structural formula is)

[0046] The sulfur-containing additive is 1,3-propanesulfonic acid lactone (PS).

[0047] The electrolyte preparation steps are as follows: In an argon atmosphere, add the prescribed amounts of carbonate additives, sulfur-containing additives, lithium salt additives and electrolyte additives to an organic solvent, then add lithium salt, and stir and mix at 10°C to obtain the electrolyte.

[0048] 2. Preparation of lithium batteries

[0049] The lithium battery of this embodiment includes a positive electrode, a negative electrode, a separator, and the electrolyte described above.

[0050] Preparation of the positive electrode: The positive electrode active material (0.25Li2MnO3·0.75LiMn) is prepared. 0.375 Ni 0.375 Co 0.25 O2, conductive agent (acetylene black) and binder (PVDF) are prepared into a positive electrode slurry in a mass ratio of 94:3:3; the positive electrode slurry is coated onto an aluminum foil current collector and vacuum dried to obtain a positive electrode sheet.

[0051] Preparation of negative electrode sheet: negative electrode active material (graphite), conductive agent (acetylene black), binder (CMC), binder (SBR) are prepared into negative electrode slurry in a mass percentage ratio of 94:1:2:3; the negative electrode slurry is coated on copper foil current collector, vacuum dried, and negative electrode sheet is obtained.

[0052] After assembling the above-mentioned positive electrode, negative electrode and Celgard2400 separator to obtain the battery cell, the battery cell is transferred into the casing, and then the electrolyte prepared in this embodiment is injected, formed and volume-adjusted to obtain the battery of this embodiment.

[0053] Example 2

[0054] 1. Electrolyte and its preparation

[0055] The electrolyte in this embodiment includes an organic solvent, carbonate additives, lithium salt, lithium salt additives, electrolyte additives, and sulfur-containing additives in a mass ratio of 84%:1%:10%:1%:1%:3%.

[0056] The organic solvent consists of cyclic carbonates (fluoroethylene carbonate FEC and ethylene carbonate EC in a 1:1 mass ratio), chain carbonates (diethyl carbonate DEC), and chain carboxylic acid esters (ethyl difluoroacetate DFAE) in a mass ratio of 15:65:20.

[0057] The carbonate additive is fluoroethylene carbonate (FEC).

[0058] The lithium salt is lithium hexafluorophosphate (LiPF6).

[0059] The lithium salt additive is lithium difluorophosphate (LiFSI).

[0060] Electrolyte additive (structural formula is) ),

[0061] The sulfur-containing additive is propylene-1,3-propanesulfonate lactone (PST).

[0062] The electrolyte preparation steps are as follows: In an argon atmosphere, add the prescribed amounts of carbonate additives, sulfur-containing additives, lithium salt additives and electrolyte additives to an organic solvent, then add lithium salt, and stir and mix at 10°C to obtain the electrolyte.

[0063] 2. Preparation of lithium batteries

[0064] The lithium battery of this embodiment includes a positive electrode, a negative electrode, a separator, and the electrolyte described above.

[0065] Preparation of the positive electrode: The positive electrode active material (0.25Li2MnO3·0.75LiMn) is prepared. 0.375 Ni 0.375 Co 0.25 O2, conductive agent (acetylene black) and binder (PVDF) are prepared into a positive electrode slurry in a mass ratio of 94:3:3; the positive electrode slurry is coated onto an aluminum foil current collector and vacuum dried to obtain a positive electrode sheet.

[0066] Preparation of negative electrode sheet: negative electrode active material (graphite), conductive agent (acetylene black), binder (CMC), binder (SBR) are prepared into negative electrode slurry in a mass percentage ratio of 94:1:2:3; the negative electrode slurry is coated on copper foil current collector, vacuum dried, and negative electrode sheet is obtained.

[0067] After assembling the above-mentioned positive electrode, negative electrode and Celgard2400 separator to obtain the battery cell, the battery cell is transferred into the casing, and then the electrolyte prepared in this embodiment is injected, formed and volume-adjusted to obtain the battery of this embodiment.

[0068] Example 3

[0069] 1. Electrolyte and its preparation

[0070] The electrolyte in this embodiment includes an organic solvent, carbonate additives, lithium salt, lithium salt additives, electrolyte additives, and sulfur-containing additives in a mass ratio of 87.9%:0.1%:10%:0.5%:0.3%:1.2%.

[0071] The organic solvent consists of cyclic carbonates (fluoroethylene carbonate and ethylene carbonate in a mass ratio of 3:1), chain carbonates (diethyl carbonate), and chain carboxylic acid esters (ethyl difluoroacetate) in a mass ratio of 5:50:8.

[0072] The carbonate additive is vinylene carbonate (VC).

[0073] The lithium salt is lithium hexafluorophosphate (LiPF6).

[0074] The lithium salt additive is lithium bis(oxalato)borate (LiBOB).

[0075] Electrolyte additive (structural formula is) ),

[0076] The sulfur-containing additive is vinyl sulfate DTD.

[0077] The electrolyte preparation steps are as follows: In an argon atmosphere, add the prescribed amounts of carbonate additives, sulfur-containing additives, lithium salt additives and electrolyte additives to an organic solvent, then add lithium salt, and stir and mix at 10°C to obtain the electrolyte.

[0078] 2. Preparation of lithium batteries

[0079] The preparation of the lithium battery is consistent with that in Example 1.

[0080] Example 4

[0081] The difference between this embodiment and Embodiment 1 is that the mass percentage of the electrolyte additive in the electrolyte is adjusted to 0.1%. The portion less than 100% in the electrolyte can be obtained by adaptively adjusting the amount of organic solvent (one or more organic solvents can be adjusted). Other steps and parameter settings are consistent with Embodiment 1.

[0082] 2. Preparation of lithium batteries

[0083] The preparation of the lithium battery is consistent with that in Example 1.

[0084] Example 5

[0085] The electrolyte in this embodiment differs from that in Example 1 in that the mass fraction of the electrolyte additive in the electrolyte is adjusted to 5%, and the portion exceeding 100% in the electrolyte can be obtained by adaptively adjusting the amount of organic solvent (one or more organic solvents can be adjusted). All other steps and parameter settings remain consistent with Example 1.

[0086] 2. Preparation of lithium batteries

[0087] The preparation of the lithium battery is consistent with that in Example 1.

[0088] Example 6

[0089] The difference between this embodiment and Example 1 is that the sulfur-containing additive in the electrolyte is adjusted to consist of propylene-1,3-sulfonyl lactone (PST) and 1,3-propanesulfonyl lactone (PS), and the mass percentages of PST and PS in the electrolyte are 1.5% and 0.5%, respectively. All other steps and parameter settings remain the same as in Example 1.

[0090] 2. Preparation of lithium batteries

[0091] The battery preparation in this embodiment is consistent with that in Example 1.

[0092] Example 7

[0093] The difference between this embodiment and Embodiment 1 is that the sulfur-containing additive in the electrolyte is adjusted to consist of 1,3-propanesulfonic acid lactone (PS) and vinyl sulfate (DTD), and the mass percentages of PS and DTD in the electrolyte are 1.5% and 1%, respectively. All other steps and parameter settings remain the same as in Embodiment 1.

[0094] 2. Preparation of lithium batteries

[0095] The battery preparation in this embodiment is consistent with that in Example 1.

[0096] Example 8

[0097] The difference between this embodiment and Example 1 is that the sulfur-containing additive in the electrolyte is adjusted to consist of propylene-1,3-sulfonyl lactone (PST) and vinyl sulfate (DTD), with PST and DTD accounting for 0.5% and 1.5% of the electrolyte by mass, respectively. All other steps and parameter settings remain the same as in Example 1.

[0098] 2. Preparation of lithium batteries

[0099] The battery preparation in this embodiment is consistent with that in Example 1.

[0100] Example 9

[0101] The difference between this embodiment and Example 1 is that the sulfur-containing additive in the electrolyte is adjusted to consist of propylene-1,3-sulfonyl lactone (PST), 1,3-propanesulfonyl lactone (PS), and vinyl sulfate (DTD), with the mass percentages of PST, PS, and DTD in the electrolyte being 0.5%, 0.5%, and 1%, respectively. All other steps and parameter settings remain the same as in Example 1.

[0102] 2. Preparation of lithium batteries

[0103] The battery preparation in this embodiment is consistent with that in Example 1.

[0104] Example 10

[0105] The difference between this embodiment and Example 1 is that the organic solvent in the electrolyte is adjusted to a mass ratio of cyclic carbonate (fluoroethylene carbonate) and chain carbonate (diethyl carbonate) of 15:85. All other steps and parameter settings remain the same as in Example 1.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that the electrolyte does not contain electrolyte additives, and the portion of the electrolyte that is less than 100% can be obtained by adaptively adjusting the amount of organic solvent (one or more organic solvents can be adjusted). All other steps and parameter settings are consistent with Example 1.

[0108] 2. Preparation of lithium batteries

[0109] The preparation of the lithium battery is consistent with that in Example 1.

[0110] Test methods

[0111] I. Room Temperature Cycling Performance Test of Lithium Batteries

[0112] At 25°C, the lithium-ion battery was charged at a constant current of 0.5C (nominal capacity) to a voltage of 4.6V, then charged at a constant voltage of 4.6V until the current ≤0.05C. After resting for 10 minutes, it was discharged at a constant current of 1C to a cutoff voltage of 2.5V. This constitutes one charge-discharge cycle. The lithium-ion battery was subjected to 1000 charge-discharge cycles at 25°C under the above conditions.

[0113] The capacity retention rate (%) of a lithium-ion battery after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of cycles of the lithium-ion battery.

[0114] The average voltage (V) of a lithium-ion battery after N cycles = discharge energy of the Nth cycle / discharge capacity of the Nth cycle, where N is the number of cycles of the lithium-ion battery.

[0115] II. High-Temperature Cycling Performance Testing of Lithium Batteries

[0116] At 45°C, the lithium-ion battery was charged at a constant current of 1.0C (nominal capacity) to a voltage of 4.6V, then charged at a constant voltage of 4.6V until the current ≤0.05C. After resting for 10 minutes, it was discharged at a constant current of 1C to a cutoff voltage of 2.5V. This constitutes one charge-discharge cycle. The lithium-ion battery was subjected to 800 charge-discharge cycles at 45°C under the above conditions.

[0117] The capacity retention rate (%) of a lithium-ion battery after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of cycles of the lithium-ion battery.

[0118] The average voltage (V) of a lithium-ion battery after N cycles = discharge energy of the Nth cycle / discharge capacity of the Nth cycle, where N is the number of cycles of the lithium-ion battery.

[0119] Table 1

[0120]

[0121]

[0122] Based on Examples 1-3, Comparative Example 1, and Table 1, it can be seen that adding the electrolyte additive of this application to the electrolyte can significantly improve the room temperature cycle performance and high temperature cycle performance of lithium-ion batteries. This is because, on the one hand, the electrolyte additive can promote the formation of dense CEI and SEI films at the positive and negative electrodes, which can prevent the lithium battery from experiencing an increase in internal resistance during cycling. On the other hand, the boron in the electrolyte additive can dissolve LiF in the electrolyte, thereby preventing the formation of an insulating LiF layer on the electrode surface and further reducing the interface impedance. All of these factors contribute to improving the cycle performance and high temperature resistance of lithium batteries.

[0123] In Comparative Example 1, without the use of electrolyte additives, the lithium battery exhibited poor cycle performance at both room temperature and high temperature, and its voltage decay was significant.

[0124] Based on Examples 1, 4-5, and Table 1, it can be seen that if the mass ratio of electrolyte additives in the electrolyte is too low (Example 4), it will affect the density and thickness uniformity of the CEI and SEI films generated at the positive and negative electrode interfaces, and will not effectively reduce side reactions. If the mass ratio of electrolyte additives in the electrolyte is too high (Example 5), it will not only reduce the stability of the electrolyte, but also cause violent interfacial reactions at the positive and negative electrodes, resulting in a decrease in the cycle capacity retention rate of the lithium-ion battery and rapid voltage decay.

[0125] Based on Examples 1, 6-9 and Table 1, it can be seen that by adjusting the combination of sulfur-containing additives, the sulfur-containing additives can work together with electrolyte additives to improve the film quality at the positive electrode and improve the stability of the electrolyte, which is beneficial to improving the high-temperature cycle capacity retention rate of lithium batteries and reducing the high-temperature voltage decay of lithium batteries.

[0126] Based on Examples 1 and 10 and Table 1, it can be seen that by selecting the organic solvent in this application, the stability of sulfur-containing additives, electrolyte additives, and carbonate additives in the electrolyte and the effect of their synergy are improved, significantly improving the film quality at the positive and negative electrodes, significantly improving the high-temperature cycle performance of lithium batteries, and alleviating the voltage decay of lithium batteries.

[0127] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application, but such modifications or substitutions are all within the scope of protection of this application.

Claims

1. An electrolyte, characterized in that: It includes organic solvents, carbonate additives, lithium salts, lithium salt additives, and electrolyte additives; the structural formula of the electrolyte additive is as follows: ； The electrolyte additive accounts for 0.3%-1% of the mass of the electrolyte.

2. The electrolyte according to claim 1, characterized in that: The electrolyte also includes sulfur-containing additives, which include at least one of propylene-1,3-propanesulfonate lactone, 1,3-propanesulfonate lactone, and vinyl sulfate. The sulfur-containing additive accounts for 0.5%-3% of the mass of the electrolyte.

3. The electrolyte according to claim 2, characterized in that: The sulfur-containing additive includes the propenyl-1,3-propanesulfonate lactone and the 1,3-propanesulfonate lactone. Alternatively, the sulfur-containing additive may include the propylene-1,3-propanesulfonic acid lactone and the vinyl sulfate; Alternatively, the sulfur-containing additive may include the 1,3-propanesulfonate lactone and the vinyl sulfate; Alternatively, the sulfur-containing additive may include the propylene-1,3-propanesulfonate lactone, the 1,3-propanesulfonate lactone, and the vinyl sulfate.

4. The electrolyte according to claim 1, characterized in that: The carbonate additives include at least one of vinylene carbonate and fluoroethylene carbonate; The carbonate additives constitute 0.01%-1% of the electrolyte by mass.

5. The electrolyte according to claim 1, characterized in that: The organic solvents include cyclic carbonates, linear carbonates, and linear carboxylic acid esters; The organic solvent accounts for 80%-90% of the mass of the electrolyte.

6. The electrolyte according to claim 5, characterized in that: In the organic solvent, the mass ratio of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester is 1-15:20-70:5-20.

7. The electrolyte according to claim 1, characterized in that: The lithium salt additive includes at least one of lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium bis(oxalate)borate, and lithium difluoro(oxalate)phosphate. The lithium salt additive accounts for 0.5%-1% of the mass of the electrolyte.

8. A lithium battery, characterized in that: Includes the electrolyte as described in any one of claims 1-7.

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