An electrolyte and its application

Abstract

This application provides an electrolyte and its application. The electrolyte includes a lithium salt, an organic solvent, and a functional additive. The functional additive has the following structural formula: By introducing specific functional additives, the electrolyte can improve its oxidation resistance under high voltage, and can also form a uniform and dense CEI film at the positive electrode to inhibit the dissolution of transition metal ions. It can also further promote the stability of the SEI film at the negative electrode. Therefore, the electrolyte provided by this application can further promote the stability of the positive and negative electrode interfaces, thereby optimizing the electrochemical performance such as the cycle performance of the battery.

Description

Technical Field

[0001] This application belongs to the field of lithium-ion battery technology, specifically relating to an electrolyte and its application. Background Technology

[0002] With the booming development of the new energy vehicle industry, the demand for high-energy-density power batteries is becoming increasingly urgent. Developing high-voltage cathode materials and compatible electrolytes has become a major research direction for next-generation high-energy-density power batteries. Lithium nickel manganese oxide (LiNi) is one such material. 0.5 Mn 1.5 Lithium-manganese oxide (LNMO) materials have attracted widespread attention due to their high voltage (4.7V, vs. Li / Li+), high energy density (up to 650Wh / kg), high theoretical specific capacity (146.7mAh / g), abundant resources, and low price. However, LNMO currently has some shortcomings that limit its application. These shortcomings include: ① In the production of lithium nickel manganese oxide, the surface is exposed to strongly oxidizing Ni. 4+ The process involves: ① oxidative decomposition of the catalytic electrolyte; ② the reaction of PF5 generated from the decomposition of LiPF6 under high potential and high temperature conditions with trace amounts of water in the electrolyte system to generate HF, which accelerates the formation of Mn in the LNMO structure. 2+ Dissolution leads to structural instability, and the dissolved Mn 2+ The negative electrode is reduced, which leads to capacity decay during electrolyte circulation.

[0003] Ion doping, surface coating, and recombination methods are used to improve LiNi 0.5 Mn 1.5 An effective way to improve the electrochemical performance of O4 materials is through synthesis. However, the methods mentioned above all involve complex processes and cumbersome modification techniques. From the perspective of electrolytes, using electrolyte additives is one of the most economical and effective ways to solve the problems associated with LNMO. Therefore, developing a high-voltage electrolyte suitable for LNMO is crucial to improving the electrochemical performance of LiNi. 0.5 Mn 1.5 The interfacial stability between the O4 electrode and the electrolyte is beneficial for improving the LiNi... 0.5 Mn 1.5 The performance of O4 batteries is of great significance. Summary of the Invention

[0004] To address the problems and shortcomings of existing technologies, this application provides an electrolyte and its application. By introducing specific functional additives, this electrolyte can improve its oxidation resistance under high voltage, while simultaneously forming a uniform and dense CEI film at the positive electrode to inhibit the dissolution of transition metal ions. It can also further promote the stability of the SEI film at the negative electrode. Therefore, the electrolyte provided by this application can further promote the stability of the positive and negative electrode interfaces, thereby optimizing the electrochemical performance of the battery, such as cycle performance.

[0005] According to a first aspect of this application, an electrolyte is provided, comprising a lithium salt, an organic solvent, and a functional additive; the functional additive has the following structural formula:

[0006]

[0007] This application, by introducing a functional additive with the above-described structure, can effectively improve the overall high-voltage stability of the electrolyte, making it less prone to oxidation under high voltage and maintaining good stability. Simultaneously, the introduction of this functional additive promotes the uniformity and stability of the CEI film at the positive electrode interface and the SEI film at the negative electrode interface, thus reducing interfacial side reactions, decreasing transition metal dissolution, and minimizing the damage of transition metal ions to the negative electrode SEI film. This effectively improves the room-temperature and high-temperature cycle performance and storage performance of the high-voltage battery system.

[0008] Specifically, among the aforementioned functional additives, firstly, the carbon-nitrogen triple bond can, to some extent, eliminate or mitigate the adverse effects of water and hydrofluoric acid in the electrolyte, reducing their harmful effects. For example, the nitrogen atom in the carbon-nitrogen triple bond has a certain electronegativity and possesses lone pairs of electrons, which can form hydrogen bonds with water molecules, restricting the free movement and reactivity of water. Furthermore, the presence of the carbon-nitrogen triple bond causes a certain electron delocalization effect in the linked molecules. This change in electron distribution can affect the polarity and chemical properties of the molecules. When additives containing carbon-nitrogen triple bonds interact with water, they cause a certain change in the electron cloud distribution of water, thereby reducing the chemical reactivity of water and decreasing the possibility of side reactions between water and other components in the electrolyte. Similarly, the nitrogen atom in the carbon-nitrogen triple bond can act as an electron pair donor, forming a complex with hydrogen ions in hydrofluoric acid to form a relatively stable complex. This complexation can reduce the effective concentration of hydrofluoric acid, thereby reducing its corrosiveness to the electrodes and electrolyte.

[0009] Secondly, the tri-nitrogen pentacyclic ring, carbonyl group, benzene ring, and nitrogen-sulfur pentacyclic ring can collectively form a large conjugated structure, which is beneficial for improving the molecular's antioxidant capacity and thermal stability. This makes it less prone to decomposition or reaction under high temperature and high pressure, slowing down the oxidative decomposition of the electrolyte, extending the electrolyte's lifespan, and reducing impurities generated by thermal decomposition, thereby improving the electrolyte's thermal stability. Furthermore, the conjugated system can interact with the electrode surface, promoting the stability of the negative electrode SEI film. It can also bind with active sites on the electrode surface through π-π interactions and hydrogen bonds, reducing the interfacial tension between the electrode and the electrolyte, allowing the electrolyte to better wet the electrode, thus improving the battery's charge-discharge efficiency and power performance, and further optimizing the battery's room temperature, high temperature cycle performance, and storage performance. In addition, this large conjugated system can form a structure similar to a "molecular wire" in the electrolyte (ions can migrate along the π electron cloud of the conjugated system), providing channels for the transport of metal ions such as lithium ions and increasing the lithium ion transport rate.

[0010] Third, the nitrogen element in the functional additives can coordinate with transition metal ions, reducing the damage of transition metal ions in the electrolyte to the negative electrode SEI film, and further improving the stability of the negative electrode SEI film during charge-discharge cycles.

[0011] Fourth, the sulfur element in the functional additives can form CEI and SEI films containing sulfides, which have better lithium conductivity, thus further improving the rate performance of the battery.

[0012] Therefore, the introduction of functional additives with the above-mentioned specific structures can further promote the stability of the positive and negative electrode interfaces, while giving the electrolyte higher high-pressure and thermal stability, thus further optimizing the battery's room temperature, high-temperature cycle performance and storage performance.

[0013] Preferably, in the functional additive, R1 includes at least one of hydrogen, alkyl chain, substituted alkyl chain, branched alkyl chain, branched substituted alkyl chain, and halogen; R2 includes at least one of hydrogen, alkyl chain, substituted alkyl chain, branched alkyl chain, branched substituted alkyl chain, and halogen; and R3 includes at least one of alkyl chain, substituted alkyl chain, branched alkyl chain, and branched substituted alkyl chain.

[0014] Preferably, in the functional additive, R1 includes hydrogen; R2 includes hydrogen; and R3 includes an alkyl chain.

[0015] Preferably, in the functional additive, R1 includes hydrogen; R2 includes hydrogen; and R3 includes —CH2—.

[0016] Preferably, the functional additive has the following structural formula:

[0017] Its CAS number is 202416-78-2.

[0018] Preferably, the functional additive accounts for 0.3–1.0 wt% of the electrolyte by mass. Controlling the mass percentage of the functional additive in the electrolyte within this range ensures that there is sufficient functional additive to improve the overall performance of the electrolyte and the battery, while also preventing excessive functional additive from affecting the function of other components in the electrolyte or the solubility of the functional additive and other electrolyte components in the solvent, thus causing a decline in the overall performance of the electrolyte and preventing the battery performance from being adequately improved.

[0019] Preferably, the electrolyte further includes a sulfur-containing additive; the sulfur-containing additive includes at least one selected from vinyl sulfite (ES), methylene disulfonate (MMDS), and vinyl sulfate (DTD). Furthermore, the addition of the sulfur-containing additive, working in conjunction with the aforementioned functional additives, not only further improves the high-voltage and heat resistance of the electrolyte, but also does not affect the function of other components in the electrolyte, thereby further improving the overall performance of the electrolyte and further enhancing the battery's room-temperature, high-temperature cycle performance, and storage performance.

[0020] Preferably, the sulfur-containing additive accounts for 0.5 to 2 wt% of the mass of the electrolyte.

[0021] Preferably, the sulfur-containing additive includes vinyl sulfite and methylene disulfonate; the mass ratio of vinyl sulfite to methylene disulfonate is 2–5:1. When the sulfur-containing additive includes both of the above substances, and the mass ratio of these two substances is limited to a specific range, the electrolyte obtained by combining the sulfur-containing additive with the above-mentioned specific functional additive has better overall performance, further promoting the stability of the positive and negative electrodes of the battery, thereby further optimizing the battery's room temperature, high temperature cycle performance, and storage performance.

[0022] Preferably, the electrolyte further includes carbonate additives; the carbonate additives include at least one of vinylene carbonate (VEC) and fluoroethylene carbonate (FEC). Furthermore, the electrolyte in this application also contains carbonate additives. These carbonate additives can form a film on the negative electrode, optimizing the stability of the battery negative electrode interface. However, if the amount added is too small, a dense SEI film cannot be formed; if the amount added is too large, it will lead to high impedance and high-temperature gas generation.

[0023] Preferably, the carbonate additives account for 0.2 to 1 wt% of the electrolyte.

[0024] Preferably, the carbonate additives include vinylene carbonate (VEC).

[0025] Preferably, the electrolyte further includes lithium salt additives, including at least one of lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), and lithium di(oxalato)borate (LiODFB). Furthermore, this application, by adding lithium salt additives to the aforementioned specific functional additives, sulfur-containing additives, and carbonate additives, can further promote the overall conductivity and lithium-ion transport efficiency of the electrolyte, enabling it to exhibit greater high-voltage resistance and thermal stability under the combined action of the aforementioned additives, ultimately further optimizing the battery performance.

[0026] Preferably, the lithium salt additive accounts for 0.5 to 1.0 wt% of the electrolyte.

[0027] Preferably, the lithium salt additive includes lithium difluorophosphate.

[0028] Preferably, the lithium salt additive includes lithium difluorophosphate and lithium bis(oxalate-borate). Selecting these two lithium salt additives is more conducive to the overall performance of the electrolyte, and therefore more beneficial to further optimization of battery performance. Preferably, the mass ratio of lithium difluorophosphate to lithium bis(oxalate-borate) is 3–6:1.

[0029] Preferably, the lithium salt includes lithium hexafluorophosphate; the concentration of lithium hexafluorophosphate in the electrolyte is 1 to 1.5 mol / L.

[0030] Preferably, the organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0031] Preferably, the organic solvent includes at least two or at least three of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0032] Preferably, the volume ratio of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate is (20-40):(0-20):(0-20):(30-50).

[0033] According to a second aspect of this application, a battery is provided, characterized in that it includes the electrolyte described above.

[0034] Preferably, the battery includes a lithium nickel manganese oxide cathode material. In particular, the electrolyte provided in this application exhibits greater adaptability to batteries with high-voltage systems, such as lithium nickel manganese oxide cathode material systems, meaning that the battery has better cycle performance and storage performance under high voltage and high temperature. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments.

[0036] Example 1

[0037] 1. Electrolyte composition and preparation

[0038] The electrolyte in this embodiment includes lithium salt, organic solvent, functional additive, sulfur-containing additive, carbonate additive, and lithium salt additive.

[0039] The lithium salt is lithium hexafluorophosphate (LiPF6), and the concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L.

[0040] The organic solvent consists of ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate. Based on the total volume of the organic solvent being 100%, the volume fraction of ethylene carbonate is 30%, the volume fraction of diethyl carbonate is 20%, and the volume fraction of methyl ethyl carbonate is 50%.

[0041] Functional additives are It accounts for 0.3 wt% of the mass in the electrolyte.

[0042] The sulfur-containing additive is methylene methane disulfonate (MMDS), which accounts for 1 wt% of the electrolyte.

[0043] The carbonate additive is ethylene ethylene carbonate (VEC), which accounts for 0.3 wt% of the electrolyte.

[0044] The lithium salt additive is lithium difluorophosphate (LiPO2F2), which accounts for 0.5 wt% of the electrolyte.

[0045] The electrolyte is prepared according to the following steps: Under an argon atmosphere, the formulated amounts of carbonate additives, lithium salt additives, sulfur-containing additives, and functional additives are added to an organic solvent, followed by the addition of lithium salt. The mixture is stirred and mixed at 10°C to obtain the electrolyte.

[0046] 2. Battery manufacturing

[0047] Preparation of lithium-ion batteries

[0048] (1) Preparation of positive electrode

[0049] Ternary material LNMO (LiNi) 0.5 Mn 1.5O4) positive electrode active material, binder PVDF (polyvinylidene fluoride) and conductive agent SP (conductive carbon black Super-P) are mixed and stirred evenly in a mass ratio of 94:3:3 to obtain positive electrode slurry. Then, the positive electrode slurry is coated onto aluminum foil through a coating process, and after vacuum drying and cold pressing, a positive electrode sheet is obtained.

[0050] (2) Preparation of negative electrode

[0051] The negative electrode material graphite, conductive agent SP (super-P conductive carbon black), binder CMC (carboxymethyl cellulose) and SBR (styrene-butadiene rubber) are mixed and stirred evenly in a mass ratio of 94:1:2:3 to obtain a negative electrode slurry. The negative electrode slurry is then coated onto copper foil through a coating process, and the negative electrode sheet is obtained after vacuum drying and cold pressing.

[0052] (3) Selection of electrolyte

[0053] The electrolyte prepared using this embodiment.

[0054] (4) Selection of the separator

[0055] Celgard2400 was chosen as the separator for lithium-ion batteries.

[0056] (5) Preparation of lithium-ion batteries

[0057] The positive electrode, separator (Celgard2400), and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The bare cell is placed in the outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a soft-pack lithium-ion battery is obtained.

[0058] Example 2

[0059] The difference between this embodiment and Embodiment 1 is that the mass percentage of the functional additive in the prepared electrolyte is adjusted to 0.15%; the rest is the same as in Embodiment 1.

[0060] Example 3

[0061] The difference between this embodiment and Embodiment 1 is that the mass percentage of the functional additive in the prepared electrolyte is adjusted to 1.5%; the rest is the same as in Embodiment 1.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 is that the mass percentage of the functional additive in the prepared electrolyte is adjusted to 0.6%; the rest is the same as in Embodiment 1.

[0064] Example 5

[0065] The difference between this embodiment and Example 1 is that the sulfur-containing additives in the prepared electrolyte are adjusted to vinyl sulfite and methylene disulfonate, and the mass ratio of these two is 3.5:1, while the total amount of sulfur-containing additives remains unchanged; the rest is the same as in Example 1.

[0066] Example 6

[0067] The difference between this embodiment and Example 1 is that the sulfur-containing additives in the prepared electrolyte are adjusted to vinyl sulfite and methyl disulfonate in a mass ratio of 7:1, and the total amount of sulfur-containing additives remains unchanged; otherwise, it is the same as Example 1.

[0068] Example 7

[0069] The difference between this embodiment and Example 1 is that the sulfur-containing additive in the prepared electrolyte is changed to vinyl sulfate (DTD); otherwise, it is the same as Example 1.

[0070] Example 8

[0071] The difference between this embodiment and Example 1 is that the carbonate additive in the prepared electrolyte is changed to fluoroethylene carbonate (FEC); the rest is the same as in Example 1.

[0072] Example 9

[0073] The difference between this embodiment and Example 1 is that the carbonate additives in the prepared electrolyte are adjusted to vinylene carbonate (VEC) and fluoroethylene carbonate (FEC), and the mass ratio of these two is 1:1, while the total amount of carbonate additives remains unchanged; the rest is the same as in Example 1.

[0074] Example 10

[0075] The difference between this embodiment and Example 1 is that the lithium salt additive in the prepared electrolyte is adjusted to lithium difluorophosphate and lithium bis(oxalate-borate) in a mass ratio of 4.5:1, and the total amount of lithium salt additive remains unchanged; the rest is the same as in Example 1.

[0076] Example 11

[0077] The difference between this embodiment and Example 1 is that the lithium salt additive in the prepared electrolyte is adjusted to lithium bis(fluorosulfonyl)imide and lithium bis(oxalato)borate, and the mass ratio of these two is 4.5:1, while the total amount of lithium salt additive remains unchanged; the rest is the same as in Example 1.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 1 is that no functional additives are added to the prepared electrolyte; otherwise, it is the same as Example 1.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the functional additives in the prepared electrolyte are adjusted to... The CAS number is 202416-80-6; the rest is the same as in Example 1.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 1 is that the functional additives in the prepared electrolyte are adjusted to... The CAS number is 35272-37-8; the rest is the same as in Example 1.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 1 is that the functional additives in the prepared electrolyte are adjusted to... The CAS number is 175473-30-0; the rest is the same as in Example 1.

[0086] Comparative Example 5

[0087] The difference between this comparative example and Example 1 is that the functional additives in the prepared electrolyte are adjusted to... The CAS number is 139540-11-7; the rest is the same as in Example 1.

[0088] Test case

[0089] 1. Experimental Construction Method

[0090] The HF content of the electrolytes prepared in all the above embodiments and comparative examples was determined, and the cycle performance and high-temperature storage performance of the batteries prepared in all the above embodiments and comparative examples were tested. The specific test methods are as follows.

[0091] (1) HF content determination

[0092] The electrolyte was stored at 45°C, and the HF content at 0d and 15d was tested by ice-water titration, and recorded as HF-0d and HF-15d respectively.

[0093] (2) Cyclic performance test

[0094] Room temperature (25℃) cycle test: Place the battery at 25℃ and record the initial capacity as A1. The capacity after 1C / 1C cycling to 1000 cycles is A2. Calculate the capacity retention rate of the battery after 1000 cycles at high temperature using the following formula: Cyclic capacity retention rate (%) = A2 / A1 × 100%.

[0095] High temperature (45℃) cycle test: Place the battery at 45℃ and record the initial capacity as A1. The capacity after 1C / 1C cycle to 1000 cycles is A2. Calculate the capacity retention rate of the battery after 1000 high temperature cycles using the following formula: Cycle capacity retention rate (%) = A2 / A1 × 100%.

[0096] The above 1C / 1C cycle refers to charging at a constant current of 1.0C (nominal capacity) to a voltage of 4.4V, then charging at a constant voltage of 4.4V to a current ≤0.05C, resting for 10 minutes, and then discharging at a constant current of 1C to 2.8V. This constitutes one charge-discharge cycle.

[0097] (3) High-temperature storage performance test

[0098] The battery was subjected to 5 charge-discharge cycles at 1C at room temperature, followed by full charge at 1C. The 1C capacity Q0 and battery volume V0 were recorded. 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 1C at room temperature for 5 weeks, and the 1C discharge capacity Q2 was recorded. Experimental data such as high-temperature storage capacity retention rate, capacity recovery rate, and volume change rate were calculated, and the results are shown in the table below. 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%.

[0099] The above-mentioned charge-discharge cycle at a charge-discharge rate of 1C or charge-discharge at a rate of 1C refers to...

[0100] Charge at 1.0C (nominal capacity) constant current to a voltage of 4.4V, then charge at 4.4V constant voltage until the current is ≤0.05C. After resting for 10 minutes, discharge at 1C constant current to 2.8V. This constitutes one charge-discharge cycle or one charge-discharge cycle.

[0101] 2. Experimental Results

[0102] The performance test results of the electrolytes and batteries prepared in all the above embodiments and comparative examples are shown in Table 1.

[0103] Table 1. Performance test results of the electrolytes and batteries prepared in the examples and comparative examples.

[0104]

[0105] As shown in Table 1, the electrolyte provided by the present invention can effectively reduce the HF content, while improving the battery's cycle performance at both room temperature and high temperature, and also improving its storage performance at high temperature. For details, please refer to Examples 1 to 11.

[0106] Comparative Example 1's electrolyte contained no functional additives; Comparative Example 2's functional additives contained no cyano groups; Comparative Example 3's functional additives contained no cyano groups or trinitrogen pentacyclic rings; Comparative Example 4's functional additives contained no benzene rings or sulfur-nitrogen pentacyclic rings; and Comparative Example 5's functional additives contained no sulfur-nitrogen pentacyclic rings or cyano groups. All of these factors contributed to an increase in the HF content of the electrolyte and a decrease in the battery's capacity retention at room temperature and high temperature cycles, as well as its high-temperature storage performance. In particular, Comparative Example 1, which did not contain any functional additives, showed a more significant increase in HF content in its electrolyte, and its battery performance also declined most significantly. This demonstrates that the specific functional additives introduced in this invention significantly improve electrolyte performance, thus effectively enhancing various aspects of battery performance. Furthermore, it also indicates that the structure of the specific functional additives introduced in this invention changes, particularly some functional groups, which has a significant impact on the performance of both the functional additives and the electrolyte, ultimately leading to a more significant decline in various aspects of battery performance.

[0107] Further comparison of Examples 1 with Examples 2-4 revealed that the content of functional additives in the electrolyte in Examples 2 and 3 was too low and too high, respectively, resulting in a decrease in the battery's capacity retention rate at room temperature and high temperature during cycling, as well as its high temperature storage performance, compared to Examples 1 and 4. This indicates that controlling the content of functional additives in the electrolyte within a specific range is more conducive to maximizing the overall performance of the electrolyte, thereby further optimizing the battery's performance.

[0108] Comparing Examples 1 and 5-7, the sulfur-containing additives in Example 5 were vinyl sulfite and methylene disulfonate in a mass ratio of 2-5:1; the sulfur-containing additives in Example 6 were also vinyl sulfite and methylene disulfonate in a mass ratio of 2-5:1; and the sulfur-containing additive in Example 7 was vinyl sulfate. The battery performance in Example 5 was slightly better than that in Example 1, while the battery performance in Examples 6 and 7 was slightly worse than that in Example 1. This indicates that the selection and ratio of sulfur-containing additives have a certain impact on the performance of the electrolyte, and selecting appropriate combinations and ratios of sulfur-containing additives is more conducive to further optimizing the performance of the electrolyte and the battery.

[0109] Comparing Examples 1 and Examples 8-11, the carbonate additives in Example 8 were fluoroethylene carbonate (FEC), in Example 9 they were vinylene carbonate (VEC) and fluoroethylene carbonate (FEC), in Example 10 they were lithium difluorophosphate and lithium bis(oxalato)borate, and in Example 11 they were lithium bis(fluorosulfonyl)imide and lithium bis(oxalato)borate. These factors resulted in the batteries in Examples 8-11 having slightly worse or better performance than those in Example 1. This indicates that selecting appropriate carbonate and lithium salt additives is more conducive to the overall performance of the electrolyte, and thus more conducive to further optimizing the relevant performance of the battery.

[0110] 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: Including lithium salts, organic solvents, and functional additives; The structural formula of the functional additive is as follows: ； R1 includes at least one of hydrogen, alkyl chain, substituted alkyl chain, branched alkyl chain, branched substituted alkyl chain, and halogen. R2 includes at least one of hydrogen, alkyl chain, substituted alkyl chain, branched alkyl chain, branched substituted alkyl chain, and halogen. R3 includes at least one of alkyl chain, substituted alkyl chain, branched alkyl chain, and branched substituted alkyl chain; The functional additive has a mass ratio of 0.3~1.0 wt% in the electrolyte.

2. The electrolyte as described in claim 1, characterized in that: In the functional additive, R1 includes hydrogen; R2 includes hydrogen; and R3 includes an alkyl chain.

3. The electrolyte as described in claim 1, characterized in that, The structural formula of the functional additive is as follows: 。 4. The electrolyte as described in claim 1, characterized in that: It also includes sulfur-containing additives; the sulfur-containing additives include at least one of vinyl sulfite, methylene disulfonate and vinyl sulfate. The sulfur-containing additive has a mass ratio of 0.5~2wt% in the electrolyte.

5. The electrolyte as described in claim 4, characterized in that: The sulfur-containing additives include the vinyl sulfite and the methylene disulfonate; The mass ratio of the vinyl sulfite to the methylene disulfonate is 2-5:

1.

6. The electrolyte as described in claim 1, characterized in that: It also includes carbonate additives; the carbonate additives include at least one of vinylene carbonate and fluoroethylene carbonate; The carbonate additives account for 0.2 to 1 wt% of the electrolyte.

7. The electrolyte as described in claim 1, characterized in that: It also includes lithium salt additives, which include at least one of lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalate)borate, lithium difluorophosphate, and lithium di(oxalate)borate. The lithium salt additive has a mass percentage of 0.5~1.0 wt% in the electrolyte.

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

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