Electrolytes, batteries and electrical devices

Abstract

This application relates to the field of battery technology, specifically to electrolytes, batteries, and electrical devices. The electrolyte comprises a solvent, an electrolyte salt, and additives, wherein the additives include fluoroethylene carbonate, lithium bis(fluorosulfonyl)imide, and a compound shown in Formula 1; Formula 1; the electrolyte salt includes LiPF6. Applying this electrolyte to a battery results in excellent safety performance, cycle performance, and high-temperature storage performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to electrolytes, batteries, and electrical devices. Background Technology

[0002] Currently, lithium-ion batteries based on graphite anodes have achieved energy densities of up to 300 Wh / kg. The most common technological approach in the industry is to further improve energy density by incorporating silicon-based anodes. However, silicon-based anodes have a significant drawback—drastic volume expansion. In a fully lithium-intercalated state, this drastic volume change causes repeated rupture of the solid electrolyte interphase (SEI) film on the electrode surface. This accelerates electrolyte consumption and causes silicon-based material particles to pulverize and detach, ultimately severely degrading the battery's electrical performance. To mitigate this problem, a large amount of fluoroethylene carbonate (FEC) is typically added to the electrolyte, and the higher the silicon content in the silicon-based anode, the stronger the dependence on FEC. However, FEC itself has poor thermal stability and easily reacts with components such as LiPF6 and EC in the electrolyte at high temperatures. This not only increases the acidity of the electrolyte but also causes a surge in gas production, directly reducing the battery's long-term high-temperature storage reliability and increasing thermal safety risks. Therefore, the electrolyte requires further improvement. Summary of the Invention

[0003] This application aims to at least partially solve one of the technical problems in the related art. To this end, this application proposes an electrolyte, a battery, and an electrical device, wherein the electrolyte is applied to the battery to enable the battery to have excellent safety performance, cycle performance, or high-temperature storage performance.

[0004] In a first aspect, this application provides an electrolyte comprising a solvent, an electrolyte salt, and an additive, said additive comprising fluoroethylene carbonate, lithium difluorosulfonylimide, and a compound shown in Formula 1. Formula 1 R1, R2, R3, and R4 each independently include at least one of H, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkenyl, acetyl, R'-substituted acetyl, and methyl isocyanate group; R' is selected from at least one of H and F; The electrolyte salt includes LiPF6.

[0005] This application simultaneously adds FEC, LiFSI and the compound of Formula 1 to the electrolyte. Through the synergistic effect of the three, the high-temperature stability of the electrolyte is effectively improved and the effective service life of the electrolyte is extended, thereby improving the safety performance, cycle performance and high-temperature storage performance of the battery.

[0006] According to embodiments of this application, R1, R2, R3, and R4 each independently include at least one of H, methyl, methoxy, and vinyl.

[0007] According to embodiments of this application, the compound of formula 1 includes at least one of the following compounds: Formula 1-1 Formula 1-2 Formula 1-3 Equations 1-4.

[0008] According to an embodiment of this application, based on the total mass of the electrolyte, the mass percentage of the fluoroethylene carbonate and the compound shown in Formula 1 is 8%-12%.

[0009] According to embodiments of this application, the total concentration of the lithium difluorosulfonylimide and the electrolyte salt is 1 mol / L to 1.3 mol / L.

[0010] According to embodiments of this application, the additive further includes: vinylene carbonate.

[0011] According to an embodiment of this application, the mass percentage of vinylene carbonate is 0.2%-1.0% based on the total mass of the electrolyte.

[0012] According to embodiments of this application, the additive further includes: a lithium salt additive, wherein the lithium salt additive includes one of LiPO2F2, LiBOB, LiODFP, and LiODFB.

[0013] According to an embodiment of this application, the mass percentage of the lithium salt additive is 0.5%-1% based on the total mass of the electrolyte.

[0014] According to embodiments of this application, the solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0015] According to the embodiments of this application, the volume ratio of the ethylene carbonate, the propylene carbonate, the dimethyl carbonate, the diethyl carbonate, and the methyl ethyl carbonate is (20~40):(0~10):(0~20):(5~20):(30~50).

[0016] A second aspect of this application provides a battery comprising the electrolyte described in the first aspect. This battery exhibits high energy density, excellent cycle performance, safety performance, and high-temperature storage performance.

[0017] According to embodiments of this application, it further includes a negative electrode sheet, the negative electrode sheet comprising a negative electrode active material, the negative electrode active material comprising a silicon-based material.

[0018] A third aspect of this application provides an electrical device comprising the battery described in the second aspect. This electrical device includes all the features and advantages of the battery described in the second aspect, which will not be elaborated upon here. Detailed Implementation

[0019] The embodiments of this application are described in detail below and are intended to explain this application, but should not be construed as limiting this application.

[0020] In the development of high-energy-density lithium-ion batteries, graphite-based lithium-ion batteries have reached an energy density of 300 Wh / kg. To further improve this, the most common approach is to incorporate silicon-based anodes. However, silicon-based anodes suffer from significant volume expansion: in a fully lithium-intercalated state, their expansion and contraction rates exceed 300%. This drastic volume change causes repeated rupture-regeneration-rupture of the solid electrolyte interphase (SEI) membrane, accelerating electrolyte consumption and causing silicon-based material particles to pulverize and detach, ultimately leading to continuous deterioration of battery performance. To mitigate these problems, a large amount of fluoroethylene carbonate (FEC) is typically added to the electrolyte to stabilize the SEI membrane; and as the silicon content in the silicon-based anode increases, the battery's dependence on FEC further increases. However, FEC itself is thermally unstable, reacting with components such as LiPF6 and ethylene carbonate (EC) at high temperatures, leading to increased electrolyte acidity and gas production, thus deteriorating the battery's long-term high-temperature storage reliability. Meanwhile, high-energy-density batteries inherently pose higher thermal safety risks. This necessitates addressing both the performance issues arising from silicon-based anodes through flux-assisted electrolysis (FEC) and the high-temperature reliability risks and inherent thermal safety challenges of the battery itself. Therefore, how to ensure the electrolyte's long-term high-temperature reliability while simultaneously resolving thermal safety issues in high-energy-density scenarios has become a critical technological bottleneck that urgently needs to be overcome in the development of high-energy-density lithium-ion batteries.

[0021] Based on the above, this application mainly optimizes the problem of poor high-temperature performance of high-silicon battery system in two aspects: (1) Using compound of formula 1 to partially replace FEC, reducing the amount of FEC used, thereby mitigating the negative impact of FEC thermal instability, and improving the high-temperature stability of battery while ensuring cycle performance; (2) Using compound of formula 1 in combination with electrolyte additive lithium bisfluorosulfonylimide (LiFSI), which can compensate for the impedance deterioration problem that compound of formula 1 may cause. At the same time, LiFSI can also replace part of the electrolyte salt, reduce the side reaction between electrolyte salt and additives and solvents, improve electrolyte stability, and improve the thermal safety and high-temperature storage performance of the system.

[0022] In view of this, a first aspect of this application provides an electrolyte comprising a solvent, an electrolyte salt, and an additive, said additive comprising fluoroethylene carbonate (FEC), lithium bis(fluorosulfonyl)imide (LiFSI), and a compound shown in Formula 1. Formula 1 R1, R2, R3, and R4 each independently include at least one of H, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkenyl, acetyl, R'-substituted acetyl, and methyl isocyanate group; R' is selected from at least one of H and F; The electrolyte salt includes LiPF6.

[0023] This application is based on the LiPF6 electrolyte salt system, and simultaneously adds FEC, LiFSI, and a compound of formula 1 to the electrolyte. Through the synergistic effect of these four components, they compensate for each other's shortcomings, significantly improving the overall performance of the electrolyte and the battery. Specifically, the effects are as follows: Firstly, the -F group at the end of the compound of formula 1 can break during the reaction and participate in the negative electrode film formation process, forming a thin SEI film rich in LiF on the negative electrode surface. This SEI film has excellent flexibility and can well adapt to large volume expansion, fundamentally reducing the repeated occurrence of SEI film rupture and regeneration, thereby improving battery cycle performance. Secondly, the compound of formula 1 can partially replace the thermally unstable FEC, reducing the total amount of FEC used in the electrolyte, thereby reducing the HF content. Simultaneously, it can also slow down the consumption rate of the remaining FEC, preventing FEC from undergoing side reactions with other components due to thermal instability, directly improving the high-temperature stability of the electrolyte. Furthermore, the nitrogen atom in the molecular structure of compound 1 contains a lone pair of electrons, exhibiting weak basicity. This effectively neutralizes HF (hydrofluoric acid) that may be generated in the electrolyte, reducing HF corrosion at the electrode interface and further improving the battery's high-temperature performance. Finally, LiFSI can compensate for the potential increase in system impedance caused by compound 1. Simultaneously, LiFSI can act as an electrolyte salt, reducing the amount of LiPF6 used and minimizing side reactions between LiPF6, additives, and solvents, thereby reducing HF content. This significantly improves the battery system's thermal safety performance while enhancing electrolyte stability. In summary, this application simultaneously adds FEC, LiFSI, and compound 1 to a LiPF6-based electrolyte salt system, fully leveraging the advantages of all four. Their synergistic effect effectively improves the high-temperature stability of the electrolyte, extends its effective lifespan, and thus enhances the battery's safety, cycle performance, and high-temperature storage performance.

[0024] The term "C1-C3 alkyl" includes, but is not limited to, methyl, ethyl, n-propyl, isopropyl, etc.

[0025] The term "C1-C3 alkoxy" includes, but is not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, etc.

[0026] The term "C2-C3 alkenyl" includes, but is not limited to, vinyl, propenyl, etc.

[0027] The term "R'-substituted acetyl" includes, but is not limited to, fluorinated substituted acetyl groups.

[0028] The technical solution of this application is particularly suitable for silicon-based anodes and can improve problems such as rapid electrolyte consumption and battery performance degradation caused by the large volume expansion of silicon-based anodes.

[0029] The description in this article, "R1 to R4 are independent of each other...", means that R1, R2, R3, and R4 are independent of each other and do not affect each other. They can be the same or different.

[0030] According to embodiments of this application, R1 to R4 each independently include at least one of H, methyl, methoxy, and vinyl.

[0031] According to embodiments of this application, the compound of formula 1 includes at least one of the following compounds: Formula 1-1 Formula 1-2 Formula 1-3 Equations 1-4.

[0032] The compound of Formula 1 above helps to reduce SEI film rupture, reduce the total amount of FEC in the electrolyte and slow down its consumption rate, and reduce the corrosion of the electrode interface by the generated HF, thereby improving the battery's safety performance, cycle performance and high-temperature storage performance.

[0033] According to embodiments of this application, based on the total mass of the electrolyte, the total mass percentage of the fluoroethylene carbonate and the compound shown in Formula 1 is 8%-12%, specifically 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, or any two of these ranges. Within the above range, this helps to reduce SEI film rupture, reduce the total amount of FEC in the electrolyte and slow down its consumption rate, and reduce the corrosion of the electrode interface by the generated HF, thereby improving the battery's safety performance, cycle performance, and high-temperature reliability.

[0034] According to embodiments of this application, the total concentration of the lithium bis(fluorosulfonyl)imide and the electrolyte salt is 1 mol / L to 1.3 mol / L, specifically within the ranges of 1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.25 mol / L, 1.3 mol / L, or any two thereof. Within this range, sufficient lithium ions can be provided to ensure ion conduction during battery charging and discharging, reducing the impedance of the electrolyte system, decreasing the amount of electrolyte salt used, thereby improving electrolyte stability and battery thermal safety performance.

[0035] According to embodiments of this application, the additive further includes vinylene carbonate (VC), wherein the mass percentage of vinylene carbonate is 0.2%-1.0% based on the total mass of the electrolyte, specifically such as 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or any range between two of these. Within the above range, it helps to induce the formation of a dense and stable SEI film on the negative electrode surface, ensuring the cycle performance and interface stability of the battery.

[0036] According to embodiments of this application, the additive further includes a lithium salt additive, wherein the lithium salt additive includes one of LiPO2F2, LiBOB, LiODFP, and LiODFB. The aforementioned lithium salt additive helps to form a denser SEI film, inhibits the dissolution of positive electrode metal ions, reduces the damage of metal ions to the negative electrode SEI film, and improves the thermal stability of the film formation.

[0037] According to embodiments of this application, based on the total mass of the electrolyte, the mass percentage of the lithium salt additive is 0.3%-1%, specifically 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or any two of these ranges. Within this range, it helps to form a denser SEI film, which can suppress the dissolution of positive electrode metal ions, reduce the damage of metal ions to the negative electrode SEI film, and improve the thermal stability of the film formation.

[0038] According to embodiments of this application, electrolyte salt and solvent are both important components of electrolyte. Together, they construct a stable ion transport system. Electrolyte salt provides sufficient lithium ions to ensure high ionic conductivity, and together improve the stability of electrolyte and the cycle life of battery, etc. Solvent can efficiently dissolve electrolyte salt and optimize lithium ion solvation environment.

[0039] According to embodiments of this application, the solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0040] According to embodiments of this application, the volume ratio of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate is (20~40):(0~10):(0~20):(5~20):(30~50). Within this range, it helps to dissolve the electrolyte salt while reducing the viscosity of the system, and after dissolving the electrolyte salt, the electrolyte can have a high ionic conductivity.

[0041] A second aspect of this application provides a battery comprising the electrolyte described in the first aspect. When this electrolyte is applied to a battery, the battery exhibits high energy density, excellent cycle performance, safety performance, and high-temperature storage performance.

[0042] According to an embodiment of the present application, the battery further includes a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0043] According to an embodiment of the present application, the negative electrode active material includes a silicon-based material. The technical solution of the present application is applicable to silicon-based materials with relatively large volume expansion (the specific capacity of silicon negative electrode > 650 mAh / g).

[0044] According to an embodiment of the present application, the negative electrode sheet further includes at least one of a negative electrode binder, a negative electrode conductive agent, and a thickening agent.

[0045] According to an embodiment of the present application, the negative electrode binder includes at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), and polyacrylamide (PAM).

[0046] According to an embodiment of the present application, the negative electrode conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, and graphene.

[0047] According to an embodiment of the present application, the thickening agent includes sodium carboxymethyl cellulose (CMC-Na).

[0048] According to an embodiment of the present application, the battery further includes a positive electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder.

[0049] According to an embodiment of the present application, the positive electrode active material includes Li(Ni x Co y Mn z )O2, where 0.8 ≤ x ≤ 1, 0 < y ≤ 0.2, 0 < z ≤ 0.2 and x + y + z = 1. The technical solution of the present application is applicable to high-nickel positive electrode materials.

[0050] According to an embodiment of the present application, the positive electrode current collector includes a metal foil. As a specific example, aluminum foil is used in the present application.

[0051] According to an embodiment of the present application, the positive electrode conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes (CNT), and graphene.

[0052] According to an embodiment of the present application, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and vinylidene fluoride-tetrafluoroethylene-propylene terpolymer.

[0053] According to embodiments of this application, the diaphragm can be made of various porous structures with good stability, such as polyethylene diaphragms, polypropylene diaphragms, PE ceramic-coated diaphragms, etc.

[0054] A third aspect of this application provides an electrical device comprising the battery described in the second aspect. This electrical device includes all the features and advantages of the battery described in the second aspect, which will not be elaborated upon here.

[0055] It is understood that there are no particular restrictions on the specific type of electrical device; it can be any device that uses a battery or battery pack as a power source or energy storage unit. For example, electrical devices include, but are not limited to, electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (such as mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, and so on.

[0056] It is understood that, in addition to the battery or battery pack mentioned above, the electrical device also includes necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0057] The embodiments of this application are described in detail below.

[0058] The compounds of Formula 1 used in the following examples can be purchased directly or prepared at home. Specifically: Example 1 1. Electrolyte preparation: In an argon-filled glove box (moisture <10ppm, oxygen <1ppm), 20% ethylene carbonate, 20% diethyl carbonate, and 60% methyl ethyl carbonate were mixed to obtain an organic solvent, based on 100% of the total volume of the organic solvent. Lithium salts LiPF6 and LiFSI were added to the organic solvent and stirred until homogeneous. Subsequently, 0.5% vinylene carbonate (VC), 6% fluoroethylene carbonate (FEC), lithium salt additives (0.5% LiPO2F2 and 0.5% LiBOB), and 6% of the compound shown in Formula 1-1 were added and stirred until homogeneous to obtain the electrolyte. The concentration of LiPF6 was 0.6 mol / L, and the concentration of LiFSI was 0.6 mol / L. 2. Preparation of the positive electrode: NCM811 (LiNi) 0.8 Co 0.1 Mn 0.1O2), positive electrode conductive agent acetylene black and positive electrode binder PVDF are dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 93:4:3 and thoroughly stirred to form a uniform positive electrode slurry with a solid content of 76%. The positive electrode slurry is uniformly coated on the positive electrode current collector Al foil, and after drying, rolling and cutting, the positive electrode sheet is obtained. 3. Preparation of negative electrode sheet: The negative electrode active material graphite, silicon material, negative electrode conductive agent acetylene black, negative electrode binder sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) are dispersed in deionized water at a mass ratio of 95:2:2:1 and thoroughly stirred to form a uniform negative electrode slurry with a solid content of 43%; the negative electrode slurry is uniformly coated on the negative electrode current collector Cu foil, and after drying, rolling and slitting, the negative electrode sheet is obtained; 4. Preparation of the diaphragm: A 12μm thick polypropylene membrane was selected as the diaphragm; 5. Battery fabrication: The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes for isolation. The stacked electrodes then form a bare cell, which is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, the lithium-ion battery is fabricated.

[0059] The specific parameters of Examples 2-22 and Comparative Examples 1-4 are listed in Table 1. All other parameters are the same as those of Example 1.

[0060] Performance testing: (1) HF content (ppm): Store the battery at 60℃ for 30 days, disassemble the battery, weigh 5g of electrolyte and dissolve it in 50ml of acetonitrile, add 3 drops of bromothymol blue indicator. Titrate with 0.01 mol / L triethylamine-EMC (triethylamine-methyl ethyl carbonate) standard solution until the yellow color changes to blue, and record the volume V of triethylamine-EMC standard solution consumed.

[0061] (2) Capacity retention rate during room temperature cycling: The battery is placed at 25°C and the initial capacity is recorded as A1. The capacity after 400 cycles at 0.5C / 1C is recorded as A2. The capacity retention rate of the battery after 400 cycles at room temperature is calculated by the following formula: Cyclic capacity retention rate (%) = A2 / A1 × 100%.

[0062] (3) High-temperature storage performance: The batteries obtained in the examples and comparative examples were subjected to 5 charge-discharge cycles at a charge-discharge rate of 1C at room temperature, and then fully charged at 1C (4.2V, 0.05A cutoff). The 1C capacity Q0 and battery volume V0 were recorded respectively. The fully charged battery was stored at 60℃ for 90 days, and the battery volume V1 and 1C discharge capacity Q1 were recorded. Then the battery was charged and discharged at a rate of 1C at room temperature for 5 weeks, and the 1C discharge capacity Q2 was recorded. The experimental data such as the battery high-temperature storage capacity retention rate, capacity recovery rate and volume change rate were calculated and recorded as shown in Table 2. The calculation formulas used are as follows: Capacity retention rate (%) = Q1 / Q0 × 100%; Capacity recovery rate (%) = Q2 / Q0 × 100%; Volume change rate (%) = (V1 - V0) / V0 × 100%.

[0063] (4) Safety performance: 1. Charge the battery at 6A to 4.2V, stop at 0.05A, and let it stand for 30 minutes (pretreatment). 2. Record the voltage, internal resistance, and weight of the battery cell; 3. Place the battery cell in a constant temperature chamber. The temperature chamber is heated to (137±2)℃ at a rate of (5±2)℃ / min and maintained for 30 minutes before stopping heating (the test chamber door can be opened to allow the sample to cool naturally). After the sample temperature drops to room temperature (70±5)℃, the test is performed (the time interval is 1 second). The highest temperature reached by the battery during the test is recorded as Tmax. The lower the value, the better the battery performance.

[0064] Table 1

[0065] Table 2

[0066] In Table 2, "OK" means that no fire or explosion occurred during the test; "NG" means that a fire or explosion occurred during the test.

[0067] As can be seen from the comparative examples in Table 2, Comparative Example 1, without the addition of LiPF6, has a lower HF content and Tmax. This is because LiFSI has better thermal stability than LiPF6, thus LiFSI plays a role in improving the stability of the high-temperature electrolyte and enhancing thermal safety performance. However, Comparative Example 1 has poor cycle performance and high-temperature storage performance because pure LiFSI corrodes the aluminum foil, thus affecting cycle and storage performance. Since FEC has poor high-temperature stability and easily decomposes to produce HF, and Comparative Example 3 did not add FEC, its HF content is lower, but it cannot simultaneously achieve good cycle performance, high-temperature storage performance, and safety performance.

[0068] This application utilizes a LiPF6-based electrolyte salt system, employing a compound of Formula 1 in conjunction with LiFSI and FEC to achieve synergistic effects, compensating for each other's shortcomings and constructing a functionally complementary electrolyte system. This electrolyte system not only reduces the amount of LiPF6 used and effectively lowers the HF content, but also achieves a comprehensive improvement in battery cycle performance, high-temperature storage performance, and safety performance.

[0069] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] 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. An electrolyte, characterized in that, It includes solvents, electrolyte salts, and additives, wherein the additives include fluoroethylene carbonate, lithium difluorosulfonylimide, and compounds shown in Formula 1; Formula 1 R1, R2, R3, and R4 each independently include at least one of H, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkenyl, acetyl, R'-substituted acetyl, and methyl isocyanate group; R' is selected from at least one of H and F; The electrolyte salt includes LiPF6.

2. The electrolyte according to claim 1, characterized in that, R1, R2, R3, and R4 each independently include at least one of H, methyl, methoxy, and vinyl.

3. The electrolyte according to claim 1, wherein the compound of formula 1 comprises at least one of the following compounds: Formula 1-1 Formula 1-2 Formula 1-3 Equations 1-4.

4. The electrolyte according to claim 1, characterized in that, At least one of the following conditions must be met: Based on the total mass of the electrolyte, the total mass percentage of the fluoroethylene carbonate and the compound shown in Formula 1 is 8%-12%; The total concentration of the lithium difluorosulfonylimide and the electrolyte salt is 1 mol / L to 1.3 mol / L.

5. The electrolyte according to claim 1, characterized in that, The additives also include: vinylene carbonate.

6. The electrolyte according to claim 5, characterized in that, Based on the total mass of the electrolyte, the mass percentage of vinylene carbonate is 0.2%-1.0%.

7. The electrolyte according to claim 5 or 6, characterized in that, The additives also include: lithium salt additives, wherein the lithium salt additives include one of LiPO2F2, LiBOB, LiODFP, and LiODFB.

8. The electrolyte according to claim 7, characterized in that, Based on the total mass of the electrolyte, the mass percentage of the lithium salt additive is 0.5%-1%.

9. The electrolyte according to claim 1, characterized in that, The solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

10. The electrolyte according to claim 9, characterized in that, The volume ratio of the ethylene carbonate, the propylene carbonate, the dimethyl carbonate, the diethyl carbonate, and the methyl ethyl carbonate is (20~40):(0~10):(0~20):(5~20):(30~50).

11. A battery, characterized in that, Includes the electrolyte according to any one of claims 1-10.

12. The battery according to claim 11, characterized in that, It also includes a negative electrode sheet, which includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

13. An electrical appliance, characterized in that, The battery includes any one of claims 11-12.

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