An electrolyte and a lithium battery

Abstract

This invention discloses an electrolyte and a lithium battery, addressing the technical problem of existing lithium batteries' inability to simultaneously achieve high-rate discharge at low temperatures and long-term cycling at high temperatures. The electrolyte of this invention is used in a lithium battery, wherein the positive electrode of the lithium battery contains a solid electrolyte. The electrolyte includes lithium salt, solvent, and additives, wherein the additives include a first type of additive A and a second type of additive B. The first type of additive A is a sulfonate ester derivative additive, and the second type of additive B is a sulfate ester derivative additive. In the above design, the first type of additive A and the second type of additive B in the electrolyte can synergistically regulate the levels of elements such as aluminum, phosphorus, titanium, zirconium, lanthanum, and sulfur in the positive electrode of the lithium battery, thereby stabilizing the positive electrode material, reducing positive electrode impedance, and effectively improving the lithium-ion transport efficiency of the positive electrode material, thus achieving a balance between high-rate discharge at low temperatures and long-term cycling at high temperatures in the lithium battery.

Description

Technical Field

[0001] This invention relates to the field of lithium battery design technology, and more particularly to an electrolyte and a lithium battery. Background Technology

[0002] Currently, to achieve high-rate discharge of lithium batteries in low-temperature environments, the main approach is to improve the transport efficiency of lithium ions in materials, electrolytes, and at the transport interface between the electrolyte and materials.

[0003] To improve the lithium-ion transport speed of materials, the common method is to dope elements such as phosphorus and sulfur into the positive electrode. However, these elements may degrade the material capacity and reduce the energy density. Adding solid electrolytes and materials through sintering and coating is difficult to process, has a low yield, and results in extremely high costs for large-scale production.

[0004] To improve the lithium-ion transport rate of electrolytes, commonly used electrolyte solvents such as carbonates suffer from drawbacks at low temperatures, including high viscosity and low conductivity. Meanwhile, carboxylic acid esters, with their lower viscosity, have a narrower electrochemical window and are prone to oxidation and reduction, which can degrade the performance of lithium batteries during high-temperature, long-cycle operation.

[0005] To reduce the impedance at the electrolyte-material interface and thus improve lithium-ion transport speed, commonly used electrolyte additives such as lithium difluorophosphate and lithium tetrafluoroborate have low solubility in common carbonates, resulting in limited improvement effects.

[0006] In summary, none of the existing common methods can effectively balance the high-rate discharge performance of lithium batteries in low-temperature environments and the long-cycle performance in high-temperature environments.

[0007] Therefore, finding a technical solution that can solve the above-mentioned technical problems has become an important research topic for those skilled in the art. Summary of the Invention

[0008] This invention discloses an electrolyte and a lithium battery, which solves the technical problem that existing lithium batteries are unable to simultaneously achieve high-rate discharge at low temperatures and long-term cycling at high temperatures.

[0009] The present invention provides an electrolyte for use in lithium batteries, wherein the positive electrode of the lithium battery contains a solid electrolyte, and the electrolyte includes a lithium salt, a solvent, and additives, wherein the additives include a first type of additive A and a second type of additive B, wherein the first type of additive A is a sulfonate derivative additive, and the second type of additive B is a sulfate derivative additive.

[0010] Optionally, the structural formula of the first type of additive A is as follows:

[0011]

[0012] Wherein, R1 is a fluorine atom or contains a trifluoromethyl group, and R2 is a methyl or ethyl group.

[0013] Optionally, the first type of additive A accounts for 0.5% to 2% of the electrolyte, and the first type of additive A includes at least one of methyl fluorosulfonate, ethyl fluorosulfonate, methyl trifluoromethanesulfonate, and ethyl trifluoromethanesulfonate.

[0014] The structural formula of the methyl fluorosulfonate is:

[0015]

[0016] The structural formula of the ethyl fluorosulfonate is:

[0017]

[0018] The structural formula of the methyl trifluoromethyl sulfonate is:

[0019]

[0020] The structural formula of the ethyl trifluoromethylsulfonate is:

[0021]

[0022] Optionally, the proportion of the second type of additive B in the electrolyte is 1% to 4%, and the second type of additive B is selected from at least one of the following sulfate ester derivatives:

[0023]

[0024] Optionally, the additive further includes a third type of additive C, wherein the third type of additive C is a nitrile compound, and the third type of additive C accounts for 2% to 4% of the electrolyte;

[0025] The third type of additive C includes one or more of adiponitrile, butadionitrile, 1,3,6-hexanetricarbonyl, trans-hexenedionitrile, trans-butenedionitrile, 1,2-di(cyanoethoxy)ethane and 1,2,3-tri(cyanoethoxy)propane.

[0026] Optionally, the additive further includes a fourth type of additive D, wherein the fourth type of additive D is fluoroethylene carbonate, which accounts for 4% to 8% of the electrolyte.

[0027] Optionally, the total mass of the lithium salt accounts for 12% to 18% of the electrolyte, and the lithium salt includes one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorosulfonyl imide, lithium difluoromethyl imide, lithium difluorooxalate phosphate, and lithium perchlorate.

[0028] The solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and ethyl difluoroacetate, wherein the proportion of ethyl propionate in the solvent is not less than 20%.

[0029] The present invention provides a lithium battery comprising a positive electrode, a negative electrode, a separator, and the electrolyte described above.

[0030] The positive electrode includes a positive current collector and a positive electrode film disposed on the positive current collector; the negative electrode includes a negative current collector and a negative electrode film disposed on the negative current collector.

[0031] The positive electrode membrane includes a positive electrode active material, a solid electrolyte, a positive electrode conductive agent, and a positive electrode binder; the negative electrode membrane includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder.

[0032] The positive electrode active material includes one of lithium cobalt oxide, ternary materials, and lithium iron phosphate.

[0033] The negative electrode active material includes one or more of graphite and silicon.

[0034] Optionally, the solid electrolyte comprises one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum titanium oxide (LLTO), and lithium lanthanum zirconium oxide (LLZO), wherein the solid electrolyte accounts for 0.5% to 2% of the mass of the positive electrode membrane, and wherein the Dv50 of the solid electrolyte is 0.4 to 0.7 μm.

[0035] Optionally, the electrolyte and the positive electrode membrane conform to the following relationship: 0.12 < (A*S) / B ≤ 4;

[0036] Wherein, A is the proportion of the first type of additive A in the electrolyte, and A is 0.5% to 2%;

[0037] Wherein, B is the proportion of the second type of additive B in the electrolyte, and B is 1% to 4%;

[0038] Wherein, S is the proportion of solid electrolyte to the mass of the positive electrode membrane, and S is 0.5% to 2%.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The first type of additive A and the second type of additive B in the electrolyte can synergistically regulate the levels of elements such as aluminum, phosphorus, titanium, zirconium, lanthanum, and sulfur in the solid electrolyte of the positive electrode sheet of the lithium battery, thereby stabilizing the positive electrode material, reducing the positive electrode impedance, and thus effectively improving the lithium-ion transport efficiency of the positive electrode material, thereby balancing the low-temperature high-rate discharge and high-temperature long-cycle operation of the lithium battery. Detailed Implementation

[0041] This invention discloses an electrolyte and a lithium battery, which solves the technical problem that existing lithium batteries are unable to simultaneously achieve high-rate discharge at low temperatures and long-term cycling at high temperatures.

[0042] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The present invention provides an electrolyte for use in lithium batteries, wherein the positive electrode of the lithium battery contains a solid electrolyte, and the electrolyte includes a lithium salt, a solvent, and additives, wherein the additives include a first type of additive A and a second type of additive B, wherein the first type of additive A is a sulfonate derivative additive, and the second type of additive B is a sulfate derivative additive.

[0044] The electrolyte in this embodiment includes a first type of additive A and a second type of additive B. The first type of additive A is a sulfonate derivative additive, and the second type of additive B is a sulfate derivative additive. The SO3 functional group of the first type of additive A is a good electron donor and can form stable complexes with transition metal elements, thereby stabilizing the cathode material, reducing cathode impedance, and effectively improving the lithium-ion transport efficiency of the cathode material. The second type of additive B can ensure good lithium-ion conductivity even at low temperatures in a low-viscosity solvent system. Simultaneously, the second type of additive B can also form a film on the cathode, creating a stable and low-resistance passivation layer on the lithium battery cathode, thus enabling high-temperature long-cycle operation of the lithium battery.

[0045] Therefore, through the above design, the first type of additive A and the second type of additive B in the electrolyte can synergistically regulate the levels of elements such as aluminum, phosphorus, titanium, zirconium, lanthanum, and sulfur in the positive electrode sheet of the lithium battery with the solid electrolyte of the positive electrode sheet, thereby stabilizing the positive electrode material, reducing the positive electrode impedance, and thus effectively improving the lithium-ion transport efficiency of the positive electrode material, thereby taking into account both the low-temperature high-rate discharge and high-temperature long-cycle of the lithium battery.

[0046] Furthermore, the structural formula of the first type of additive A in this invention is as follows:

[0047]

[0048] Wherein, R1 is a fluorine atom or contains a trifluoromethyl group, and R2 is a methyl or ethyl group.

[0049] Specifically, the proportion of the first type of additive A in the electrolyte is 0.5% to 2%. In some specific embodiments, the above proportion can be 0.5%, 1.5%, 1%, 8%, 2%, etc., and this embodiment does not limit it.

[0050] Furthermore, the first type of additive A in this invention specifically includes at least one of methyl fluorosulfonate, ethyl fluorosulfonate, methyl trifluoromethanesulfonate, and ethyl trifluoromethanesulfonate:

[0051] The structural formula of the methyl fluorosulfonate is:

[0052]

[0053] The structural formula of the ethyl fluorosulfonate is:

[0054]

[0055] The structural formula of the methyl trifluoromethyl sulfonate is:

[0056]

[0057] The structural formula of the ethyl trifluoromethylsulfonate is:

[0058]

[0059] It should be noted that designers can choose the appropriate Class I additive A based on the actual design situation.

[0060] Furthermore, the proportion of the second type of additive B in the electrolyte is 1% to 4%. In some specific embodiments, the above proportion can be 1%, 1.5%, 2%, 2.5%, 3%, 3.2%, 4%, etc., and this embodiment does not limit it.

[0061] Specifically, the second type of additive B of the present invention is selected from at least one of the following sulfate ester derivatives:

[0062]

[0063] It should be noted that designers can select the appropriate Class II additive B according to the actual design situation.

[0064] In addition, the second type of additive B in this invention can ensure good lithium-ion conductivity even at low temperatures in a low-viscosity solvent system. Both the second type of additive B and fluoroethylene carbonate can form a low-resistance passivation layer on the negative electrode, reducing the deterioration of the negative electrode impedance caused by nitrile compounds after reduction. At the same time, additive B can also form a film on the positive electrode, making up for the problem of insufficient protection of the positive electrode due to the low content of nitrile additives. Thus, a stable and low-resistance passivation layer is formed on the positive and negative electrodes of the lithium battery, thereby achieving high-temperature long-cycle operation of the lithium battery.

[0065] Furthermore, the additives in this embodiment also include a third type of additive C, wherein the third type of additive C is a nitrile compound, and the third type of additive C accounts for 2% to 4% of the electrolyte. In some specific embodiments, the above proportion can be 2%, 2.2%, 3%, 3.2%, 4%, etc., and this embodiment does not limit it.

[0066] Specifically, the third type of additive C of the present invention includes one or more of adiponitrile, butadionitrile, 1,3,6-hexanetricarbonyl, trans-hexenedionitrile, trans-butenedionitrile, 1,2-di(cyanoethoxy)ethane and 1,2,3-tri(cyanoethoxy)propane.

[0067] It should be noted that designers can choose the appropriate third-class additive C according to the actual situation.

[0068] Furthermore, the additives in this invention also include a fourth type of additive D, wherein the fourth type of additive D is fluoroethylene carbonate, which accounts for 4% to 8% of the electrolyte. In some specific embodiments, the above proportion can be 4%, 4.2%, 5%, 6%, 6.5%, 7%, 8%, etc., and this embodiment does not limit this.

[0069] Furthermore, the total mass of lithium salt in the present invention accounts for 12% to 18% of the electrolyte. In some specific embodiments, the above proportion can be 12%, 13%, 14%, 13.5%, 16%, 17%, 18%, etc., and this embodiment does not limit it.

[0070] Specifically, the lithium salt in this invention includes one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorosulfonyl imide, lithium ditrifluoromethyl imide, lithium difluorooxalate phosphate, and lithium perchlorate.

[0071] Furthermore, the solvent in this embodiment includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and ethyl difluoroacetate.

[0072] In this embodiment, the proportion of ethyl propionate in the solvent is not less than 20%. In some specific embodiments, the above proportion can be 21%, 25%, 30%, 28%, 33%, etc., and this embodiment does not limit it.

[0073] The present invention provides a lithium battery, comprising a positive electrode, a negative electrode, a separator, and the electrolyte described above;

[0074] The positive electrode includes a positive current collector and a positive electrode film disposed on the positive current collector; the negative electrode includes a negative current collector and a negative electrode film disposed on the negative current collector.

[0075] The positive electrode membrane includes a positive electrode active material, a solid electrolyte, a positive electrode conductive agent, and a positive electrode binder; the negative electrode membrane includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder.

[0076] The positive electrode active material includes one of lithium cobalt oxide, ternary materials, and lithium iron phosphate.

[0077] The negative electrode active material includes one or more of graphite and silicon.

[0078] Specifically, the solid electrolyte includes one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum titanium oxide (LLTO), and lithium lanthanum zirconium oxide (LLZO). The solid electrolyte accounts for 0.5% to 2% of the mass of the positive electrode membrane. In some specific embodiments, the above proportion can be 0.5%, 1.5%, 1.8%, 2%, etc., and this embodiment does not limit it.

[0079] Furthermore, the Dv50 of the solid electrolyte is 0.4 to 0.7 μm. In some specific embodiments, the Dv50 can be 0.4 μm, 0.5 μm, 0.7 μm, etc., and this embodiment does not limit it.

[0080] Furthermore, in this embodiment, the electrolyte and the positive electrode membrane conform to the following relationship:

[0081] 0.12 < (A*S) / B ≤ 4. In some specific implementations, (A*S) / B can be 0.13, 0.5, 0.66, 0.8, 2, 2.67, 3, 4, etc.

[0082] Wherein, A is the proportion of the first type of additive A in the electrolyte, and A is 0.5% to 2%. In some specific embodiments, the above proportion can be 0.5%, 1.5%, 1%, 8%, 2%, etc., and this embodiment does not limit it.

[0083] Wherein, B is the proportion of the second type of additive B in the electrolyte, and B is 1% to 4%. In some specific embodiments, the above proportion can be 1%, 1.5%, 2%, etc., and this embodiment does not impose any limitations.

[0084] Wherein, S is the proportion of solid electrolyte to the mass of the positive electrode film, and S is 0.5% to 2%. In some specific embodiments, the above proportion can be 0.5%, 1.5%, 1.8%, 2%, etc., and this embodiment does not limit it.

[0085] It should be noted that by designing the first type of additive A, the second type of additive B, and the solid electrolyte in the above relationship, the lithium battery can simultaneously achieve both low-temperature rate discharge and high-temperature long-cycle performance.

[0086] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments. These embodiments are implemented on the premise of the technical solution of the invention, and provide detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0087] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0088] Example 1:

[0089] Lithium-ion battery manufacturing:

[0090] (1) Preparation of electrolyte

[0091] In a glove box with an argon atmosphere containing <1 ppm of water, propylene carbonate (PC) and ethyl propionate (EP) were mixed at a mass ratio of 25:75. Based on the total mass of the electrolyte, the following components, as shown in Table 1, were added and mixed thoroughly to obtain the electrolyte.

[0092] Lithium salt: 13% lithium hexafluorophosphate (LiPF6) + 2% lithium bis(fluorosulfonyl)imide (LiFSI)

[0093] Category 1 additives: 0.5% methyl fluorosulfonate;

[0094] Second-class additive: 1% of structural formula 2;

[0095] Category III additives: 3% succinic anionyl nitrile (SN);

[0096] Category IV additives: 6% fluoroethylene carbonate (FEC);

[0097] Solvent: equal to 100% minus the mass fraction of lithium salt and all additives, added at a ratio of propylene carbonate: ethyl propionate = 1:3.

[0098] (2) Preparation of positive electrode sheet

[0099] The positive electrode active material lithium cobalt oxide (LiCoO2), lithium aluminum titanium phosphate solid electrolyte (particle size D50 of 0.5μm), conductive agent carbon black, binder polyvinylidene fluoride PVDF, and carbon nanotubes CNT were thoroughly mixed in N-methylpyrrolidone solvent at a mass ratio of 97.7:0.5:0.5:0.9:0.4 to form a uniform positive electrode slurry.

[0100] The positive electrode slurry is uniformly coated onto the positive electrode current collector aluminum foil, and then dried, rolled, and compacted (compacted density is 4.25 g / cm³). 3 The positive electrode sheet is obtained through processes such as ( ).

[0101] (3) Preparation of negative electrode sheet

[0102] The negative electrode active material graphite, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were mixed in an appropriate amount of deionized water solvent at a mass ratio of 98.2:1:0.8 to form a uniform negative electrode slurry.

[0103] The negative electrode slurry was uniformly coated onto the negative electrode current collector copper foil, and then dried, rolled, and compacted (compacted density was 1.73 g / cm³). 3 The negative electrode sheet is obtained through processes such as […].

[0104] (4) Preparation of lithium batteries

[0105] PE porous polymer film is used as the separator.

[0106] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The stacked electrodes and separator are then wound together to form a core. The bare core is placed in a pre-formed aluminum-plastic film, and the electrolyte prepared above is injected into the baked and dried core at an injection rate of 1.5 g / Ah. After vacuum sealing, settling, and formation processes, the lithium-ion battery is successfully manufactured.

[0107] Other embodiments and comparative examples use the same method as Example 1, the difference being the type and content of additives A and B in the electrolyte, and the type and amount of solid electrolyte in the positive electrode sheet, as detailed in Table 1.

[0108] Lithium battery performance testing:

[0109] (1) Discharge performance test at -29℃:

[0110] At room temperature, charge to 4.48V using a constant current and constant voltage of 0.5C, with a cutoff current of 0.05C, and let stand for 10 minutes; then discharge to 3V using a constant current of 0.2C, recording the discharge capacity as C1, and let stand for 10 minutes. Charge to 80% of C1 capacity using a constant current and constant voltage of 0.5C, with a cutoff current of 0.05C. After standing at -29℃ for 3 hours, discharge at 10.67W for 5 seconds, 14.35W for 1 second, 20.49W for 5 seconds, 11.23W for 3 seconds, 13.20W for 2 seconds, 7.3W for 10 seconds, and 4.21W for 60 seconds. If the voltage during the discharge process is not less than 3V, the test is recorded as "passed"; otherwise, it is recorded as "failed". The test results are recorded in Table 1.

[0111] (2) Cyclic performance test at 45℃:

[0112] After capacity testing, the battery was left to stand at 45℃ for 2 hours, then discharged at a constant current of 0.5C to 3V; left to stand for 10 minutes, then charged at a constant current of 1.85 to 4.3V, and then charged at a constant current and voltage of 1.5C to 4.48V, with a cutoff current of 0.05C. After standing for 10 minutes, the battery was discharged at 0.5C to 3V, and this cycle was repeated. The discharge capacity of this cycle was recorded as the initial capacity. After 500 cycles using the same charge-discharge method, the capacity retention rate after 500 cycles was calculated using the following formula. A capacity retention rate higher than 80% indicates that the test is passed.

[0113] Cycle capacity retention rate (%) at week 500 = (Cycle discharge capacity at week 500 / Initial cycle discharge capacity) × 100%.

[0114] Table 1

[0115]

[0116]

[0117]

[0118]

[0119]

[0120] Based on Implementations 1-11 and all comparative examples in Table 1, it can be found that:

[0121] Type I additive A and solid electrolyte are necessary conditions for achieving low-temperature discharge of lithium batteries. However, when the content of Type I additive A exceeds 1%, it deteriorates the 45°C cycle to a certain extent. This may be because unused Type I additive A is prone to transesterification with the solvent to generate easily oxidized solvent.

[0122] The reason why increasing the solid electrolyte content by more than 1% may cause the high-temperature long-cycle performance to deteriorate may be that the increased solid electrolyte content leads to more lithium being extracted and inserted during lithium battery charging, which reduces the stability of the positive electrode structure and thus deteriorates the high-temperature long-cycle performance.

[0123] The second type of additive B has a significant effect on improving the 45°C cycle, but increasing its content will lead to an increase in electrolyte viscosity and a deterioration of low-temperature discharge.

[0124] Based on Examples 12-21 and all comparative examples in Table 1, it can be found that:

[0125] When the first additive is replaced with other sulfonates, and the solid electrolyte is replaced with other types, the same effect is achieved. Moreover, when the relationship 0.12 < (A*S) / B ≤ 4 is satisfied, the lithium battery can achieve both low-temperature high-rate discharge and good high-temperature long-cycle performance.

[0126] Based on all the embodiments and comparative examples, it can be found that when the content of the first type of additive A is between 0.5% and 2%, the content of the second type of additive B is between 1% and 4%, the content of the solid electrolyte is between 0.5% and 2%, and the relationship 0.12 < (A*S) / B ≤ 4 is satisfied, the lithium battery can simultaneously achieve low-temperature high-rate discharge and high-temperature long-cycle.

[0127] The electrolyte and lithium battery provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An electrolyte for use in a lithium battery, wherein the positive electrode of the lithium battery contains a solid electrolyte, the positive electrode comprising a positive current collector and a positive electrode film disposed on the positive current collector, characterized in that, The electrolyte comprises lithium salt, solvent, and additives, wherein the additives include a first type of additive A and a second type of additive B, the first type of additive A being a sulfonate ester derivative additive and the second type of additive B being a sulfate ester derivative additive, wherein the first type of additive A accounts for 0.5% to 2% of the mass of the electrolyte; the solid electrolyte accounts for 0.5% to 2% of the mass of the positive electrode membrane. The structural formula of the first type of additive A is as follows: ； Wherein, R1 is a fluorine atom or contains a trifluoromethyl group, and R2 is a methyl or ethyl group; The second type of additive B accounts for 1% to 4% of the mass of the electrolyte, and the second type of additive B is selected from at least one of the following sulfate derivatives: ； The electrolyte and the positive electrode membrane conform to the following relationship: 0.12 < (A*S) / B ≤ 4; Wherein, A is the proportion of the first type of additive A in the electrolyte, and A is 0.5% to 2%; Wherein, B is the proportion of the second type of additive B in the electrolyte, and B is 1% to 4%; Wherein, S is the proportion of solid electrolyte to the mass of the positive electrode membrane, and S is 0.5% to 2%.

2. The electrolyte according to claim 1, characterized in that, The first type of additive A includes at least one of methyl fluorosulfonate, ethyl fluorosulfonate, methyl trifluoromethanesulfonate, and ethyl trifluoromethanesulfonate: The structural formula of the methyl fluorosulfonate is: ； The structural formula of the ethyl fluorosulfonate is: ； The structural formula of the methyl trifluoromethyl sulfonate is: ； The structural formula of the ethyl trifluoromethylsulfonate is: 。 3. The electrolyte according to claim 1, characterized in that, The additive also includes a third type of additive C, wherein the third type of additive C is a nitrile compound, and the third type of additive C accounts for 2% to 4% of the electrolyte; The third type of additive C includes one or more of adiponitrile, butadionitrile, 1,3,6-hexanetricarbonyl, trans-hexenedionitrile, trans-butenedionitrile, 1,2-di(cyanoethoxy)ethane and 1,2,3-tri(cyanoethoxy)propane.

4. The electrolyte according to claim 1, characterized in that, The additives also include a fourth type of additive D, wherein the fourth type of additive D is fluoroethylene carbonate, which accounts for 4% to 8% of the electrolyte.

5. The electrolyte according to claim 1, characterized in that, The total mass of the lithium salt accounts for 12% to 18% of the electrolyte, and the lithium salt includes one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorosulfonyl imide, lithium difluoromethyl imide, lithium difluorooxalate phosphate, and lithium perchlorate. The solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and ethyl difluoroacetate, wherein the proportion of ethyl propionate in the solvent is not less than 20%.

6. A lithium battery, characterized in that, Includes a positive electrode, a negative electrode, a separator, and an electrolyte as described in any one of claims 1 to 5; The negative electrode sheet includes a negative electrode current collector and a negative electrode film disposed on the negative electrode current collector; The positive electrode membrane includes a positive electrode active material, a solid electrolyte, a positive electrode conductive agent, and a positive electrode binder; the negative electrode membrane includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The positive electrode active material includes one of lithium cobalt oxide, ternary materials, and lithium iron phosphate; the negative electrode active material includes one or more of graphite and silicon.

7. The lithium battery according to claim 6, characterized in that, The solid electrolyte comprises one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum titanium oxide (LLTO), and lithium lanthanum zirconium oxide (LLZO), and wherein the Dv50 of the solid electrolyte is 0.4 to 0.7 μm.

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