Electrolyte containing functional additive and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to an electrolyte containing a functional additive and a lithium ion battery. The electrolyte comprises an organic solvent, a lithium salt and an electrolyte additive, wherein the electrolyte additive comprises a functional additive A and a functional additive B; the functional additive A and the functional additive B construct an interface system with high stability, high conductivity and self-adaptive capacity through a triple mechanism of'component complementation-dynamic cooperation-dynamic repair '. Inorganic lithium fluoride and lithium sulfide generated by decomposition of the functional additive A can enhance interface rigidity and inhibit dissolution of transition metal, an organic network formed by crosslinking of the functional additive B has hydrophobic property to inhibit hydrolysis of lithium salt, and the inorganic lithium fluoride and the lithium sulfide jointly construct an inorganic-organic hybrid interface, so that the content of inorganic lithium salt in a CEI layer is increased to enhance stability, and the service life of the CEI layer is prolonged. And the interface conductivity is regulated and controlled through an organic phase, so that the balance between the stability and the ion transmission efficiency is realized.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an electrolyte containing functional additives and a lithium-ion battery. Background Technology

[0002] With the surge in demand for high-energy-density batteries from new energy vehicles, energy storage systems, and consumer electronics, ternary lithium-ion batteries have become the mainstream choice due to their superior energy density. However, their rapid performance degradation at high temperatures (>45°C) has become a core pain point and industry bottleneck restricting their widespread application. High temperatures not only accelerate electrolyte decomposition, trigger phase transitions in cathode materials and dissolution of transition metal ions, leading to irreversible capacity loss and a sharp drop in cycle life, but also exacerbate interfacial side reactions, significantly increasing the risk of thermal runaway and seriously threatening system safety. Especially in harsh conditions such as high-temperature regions, fast-charging / high-rate applications, and closed battery packs, the internal temperature rise of the battery is even more prominent, and high-temperature stability has become a key performance indicator determining battery reliability, safety, and market acceptance. Therefore, developing ternary lithium-ion battery technology with excellent high-temperature performance is of great strategic significance for breaking through current industry development bottlenecks, enhancing product competitiveness, and ensuring user safety. Summary of the Invention

[0003] The purpose of this invention is to provide an electrolyte containing a combination of functional additives and a lithium-ion battery, which solves the problem of poor high-temperature storage of ternary batteries in the prior art.

[0004] This invention is achieved through the following technical solution: This invention discloses an electrolyte containing functional additives, comprising an organic solvent, a lithium salt, and an electrolyte additive, wherein the electrolyte additives include functional additive A and functional additive B; Based on the total mass of the electrolyte being 100%, functional additive A accounts for 0.3% to 1%, functional additive B accounts for 0.5% to 1%, lithium salt accounts for 10% to 15%, and the remainder is organic solvent; The structural formula of functional additive A is as follows:

[0005] Wherein, R is selected from substituted or unsubstituted sulfonyl groups, and the substituents are halogens, C2-C3 alkenyl groups, methyl groups, and cyano groups; Functional additive B is selected from at least one of the following structural formulas: , , .

[0006] Furthermore, functional additive A is selected from at least one of the following structural formulas: , , , , , .

[0007] Furthermore, the lithium salt is lithium hexafluorophosphate or lithium bisfluorosulfonylimide.

[0008] Furthermore, electrolyte additives also include sulfur-containing additives, carbonate additives, and lithium salt additives.

[0009] Furthermore, by mass percentage, sulfur-containing additives account for 0.5% to 1.5%, carbonate additives account for 0.2% to 0.5%, and lithium salt additives account for 0.5% to 1%.

[0010] Furthermore, the sulfur-containing additives include at least one of vinyl sulfate, 1,3-propenesulfonate lactone, and methylene disulfonate; Carbonate additives include ethylene carbonate.

[0011] Furthermore, the lithium salt additive includes at least one of lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalate-borate), and lithium bis(fluorooxalate-borate).

[0012] Furthermore, the organic solvents include cyclic carbonates and chain carbonates, with cyclic carbonates including fluoroethylene carbonate, ethylene carbonate, and propylene carbonate, and chain carbonates including diethyl carbonate and methyl ethyl carbonate.

[0013] Furthermore, based on the total mass of organic solvents being 100%, the total mass of cyclic carbonates is 22%–26%, diethyl carbonate is 10%–20%, and methyl ethyl carbonate is 50%–70%.

[0014] The present invention also discloses a lithium-ion battery, comprising a positive electrode and a negative electrode, characterized in that it further comprises the electrolyte.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides an electrolyte containing a combination of functional additives. Functional additives A and B, through a triple mechanism of "component complementarity, kinetic synergy, and dynamic repair," construct an interface system possessing high stability, high conductivity, and self-adaptive capabilities. Essentially, it constructs a stable and adaptive electrode interface system through functional synergy: In terms of component complementarity, the inorganic lithium fluoride and lithium sulfide generated from the decomposition of functional additive A enhance interfacial rigidity and inhibit transition metal dissolution, while the organic network formed by the cross-linking of functional additive B possesses hydrophobic properties to inhibit lithium salt hydrolysis. Together, they construct an "inorganic-organic" hybrid interface, which both increases the content of inorganic lithium salts in the CEI layer to enhance stability and regulates interfacial conductivity through the organic phase, achieving a balance between stability and ion transport efficiency. In terms of kinetic synergy, the decomposition product SO3 of functional additive A... 2- It can form charge transfer complexes with the acrylate double bonds in functional additive B, reducing the curing initiation temperature and polymerization activation energy of functional additive B, thus facilitating low-temperature in-situ film formation. At the same time, the network structure of functional additive B can reduce the contact area between the electrolyte and the positive electrode, thereby reducing the decomposition amount of functional additive A. The inorganic lithium salt generated by functional additive A can neutralize the acidic substances that may be generated during the polymerization of functional additive B, maintain the stability of electrolyte pH, and optimize the overall reaction kinetics. In terms of dynamic repair, when the negative electrode SEI is damaged by lithium dendrite penetration, functional additive A can decompose again in the local high current area to generate inorganic lithium salts (such as lithium fluoride and lithium sulfide) to fill the defects. When microcracks appear in the positive electrode CEI, the network of functional additive B can achieve repair through the reversible chain segment movement of "de-crosslinking-re-crosslinking". Together, they ensure the continuous integrity of the interface during battery cycling, ultimately providing long-life and high-stability interface support for ternary batteries. Attached Figure Description

[0016] Figure 1 The DCR growth rate of the electrolyte prepared in some embodiments and comparative examples of the present invention during high-temperature storage is shown. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0018] The detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0020] The main objective of this invention is to provide an electrolyte additive, an electrolyte, and a lithium-ion battery to solve the problem of capacity decay during high-temperature storage in related technologies.

[0021] The present invention provides an electrolyte comprising an organic solvent, a lithium salt, and an electrolyte additive, wherein the electrolyte additive comprises a combination of functional additives.

[0022] To achieve the above objectives, the present invention provides a combination of functional additives, including functional additive A and functional additive B.

[0023] The general structural formula of functional additive A is shown in Formula I:

[0024] R is selected from substituted or unsubstituted sulfonyl groups (substituted by halogen, C2-C3 alkenyl, methyl and cyano groups).

[0025] Electrolyte functional additives are selected from at least one of the following structures.

[0026]

[0027] The synthesis method of functional additive A is as follows: Step 1, Cycloning: Under argon protection, 1-benzyloxy-2,3-propanediol (1.96 g, 10.0 mmol) was dissolved in 30 mL of anhydrous dichloromethane. With vigorous stirring, anhydrous pyridine (0.87 mL, 11.0 mmol) and freshly distilled thionyl chloride (0.77 mL, 10.5 mmol) were simultaneously and slowly added dropwise over 1.5 hours using two constant-pressure dropping funnels, with the temperature strictly controlled below -70°C. After titration, stirring was continued at -78°C for 1 hour, followed by a slow rise to 0°C. Pyridine hydrochloride was rapidly removed by filtration. The filtrate was then rotary evaporated under reduced pressure at 0°C to obtain approximately 2.2 g of a pale yellow oily intermediate ((R)-(benzyloxymethyl)-1,3,2-dioxothiacyclopentane-2-oxide), which could be used directly in the next step without further purification.

[0028] Step 2, Deprotection: The above intermediate was dissolved in 30 mL of anhydrous ethanol, and 10% Pd / C catalyst (100 mg) was added. The mixture was stirred at room temperature for 3 hours under a hydrogen atmosphere. After the reaction was completed by TLC monitoring, the reaction solution was filtered through a diatomaceous earth pad, and the filtrate was concentrated under reduced pressure below 30 °C to obtain approximately 1.2 g of the colorless oily target product 1-hydroxymethyl-vinyl sulfite.

[0029] The third step involves reacting the obtained 1-hydroxymethyl-vinyl sulfite under sulfonyl fluoride gas to generate 1-((fluorosulfonyl)oxy)methyl-vinyl sulfite, which is then further oxidized to obtain the functional additive used in this invention.

[0030] Functional additive B is selected from at least one of the following structural formulas:

[0031] Organic solvents include cyclic carbonates and chain carbonates, wherein cyclic carbonates include fluoroethylene carbonate, ethylene carbonate, and propylene carbonate, and chain carbonates include diethyl carbonate and methyl ethyl carbonate. Cyclic carbonates have high dielectric constants and are used for dissociating lithium salts, and have high viscosity; chain carbonates have lower viscosity and are used as cosolvents in combination with cyclic carbonates.

[0032] Preferably, based on the total mass of the organic solvent as 100%, the total mass of the cyclic carbonate accounts for 22% to 26%, the mass of diethyl carbonate is 10% to 20%, and the mass of methyl ethyl carbonate is 50% to 70%.

[0033] Preferably, the electrolyte additives also include sulfur-containing additives, carbonate additives, and lithium salt additives.

[0034] Sulfur-containing additives include at least one of vinyl sulfate (DTD), 1,3-propenesulfonate lactone (PST), and methylene disulfonate (MMDS).

[0035] Sulfur-containing additives enhance battery performance through dual interface regulation: a dense and stable solid electrolyte interface (SEI) film is formed on the negative electrode side to inhibit the continuous decomposition of the electrolyte, reduce interfacial impedance, and improve the lithium-ion migration rate; a protective cathode electrolyte interface (CEI) film is constructed on the positive electrode side to simultaneously block the corrosion of the cathode material and the excessive oxidation and decomposition of the electrolyte.

[0036] Carbonate additives include ethylene carbonate (VC); VC is an unsaturated compound that readily gains electrons and is reduced at the negative electrode. When added to the electrolyte, it preferentially decreases at the negative electrode compared to other solvents during formation, participating in the formation of the protective electrolyte interphase (SEI) film. The VC film formed at the negative electrode is a pectin-like polymer-rich film with good hydrophilicity, which facilitates electrolyte retention on the SEI film and reduces the negative impact of localized electrolyte drying.

[0037] The lithium salt additives include at least one of lithium difluorophosphate (LiPO2F2), lithium bis(oxalate-borate) (LiBOB), and lithium bis(oxalate-borate) (LiODFB).

[0038] The role of lithium salt additives: Boron / phosphorus lithium salts (LiDFOB / LiPO2F2) preferentially oxidize on the positive electrode surface to form a dense BO / POF-based CEI film, inhibiting the dissolution of transition metals and the oxidative decomposition of the electrolyte under high voltage; they also optimize the negative electrode interface, allowing anions (such as DFOB) to react with the lithium salts. - The reduction of LiF-LiBOB composite SEI enhances mechanical strength and accelerates the formation of Li. + Migration (40% reduction in interface impedance) effectively suppresses lithium dendrites; improved kinetics and lifetime, dual lithium salt systems (such as LiPF6-LiFSI) enhance ionic conductivity through anion synergistic effect, improving low-temperature / rate performance.

[0039] Preferably, based on the total mass of the electrolyte as 100%, functional additive A accounts for 0.3% to 1%, functional additive B accounts for 0.5% to 1%, sulfur-containing additives account for 0.5% to 1.5%, carbonate additives account for 0.2% to 0.5%, and lithium salt additives account for 0.5% to 1%.

[0040] Preferably, the lithium salt is lithium hexafluorophosphate (LiPF6) or lithium bisfluorosulfonyl imide (LiFSi), and the mass percentage of the lithium salt in the electrolyte is 10% to 15%.

[0041] Example 1 Based on the mass percentage of the components, the electrolyte formulation used in this embodiment is as follows: Functional additive A: 0.3% (Formula I-1), Functional additive B: 0.5% (Formula II-1), LiODFB: 0.5%, PST: 0.5%, VC: 0.5%, LiPF6: 12.5%, and the balance is organic solvent components.

[0042] The organic solvent component in the above electrolyte formulation consists of fluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate. Based on the total mass of the organic solvents being 100%, the mass percentages are: fluoroethylene carbonate 3%, ethylene carbonate 14%, propylene carbonate 6%, diethyl carbonate 15%, and methyl ethyl carbonate 62%. Different embodiments are set up using the functional additives in the above formulation as variables.

[0043]

[0044] Example 2 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the amount of functional additive B added to the electrolyte is 0.7%, while the rest is the same as in Embodiment 1.

[0045] Example 3 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the functional additive A, as shown in Formula I-2, is added to the electrolyte at a rate of 0.7%, while the rest is the same as in Embodiment 1.

[0046]

[0047] Example 4 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the functional additive B, such as Formula II-2, is added to the electrolyte at a concentration of 1%, while the rest is the same as in Embodiment 1.

[0048] Example 5 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the functional additive A, as shown in Formula I-5, is added to the electrolyte at a rate of 0.5%, while the rest is the same as in Embodiment 1.

[0049]

[0050] Example 6 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the functional additive A, as shown in Formulas 1-6, is added to the electrolyte at a rate of 0.5%, while the rest is the same as in Embodiment 1.

[0051]

[0052] Example 7 This embodiment provides an electrolyte that differs from Example 1 only in that the amount of sulfur-containing additive PST is adjusted to 1%, while the rest is the same as Example 1.

[0053] Example 8 This embodiment provides an electrolyte that differs from Example 1 only in that the sulfur-containing additive PST is replaced with DTD, and the addition amount is 1.5%. Otherwise, it is the same as Example 1.

[0054] Example 9 This embodiment provides an electrolyte that differs from Example 1 only in that the sulfur-containing additive PST is replaced with MMDS at a dosage of 0.5%, while the rest is the same as in Example 1.

[0055] Example 10 This embodiment uses the electrolyte formulation used in Example 1 as a reference, and the amount of vinylene carbonate added in the formulation as a variable. The amount of VC added in Example 1 is adjusted to 0.2%, and the rest is the same as in Example 1.

[0056] Example 11 This embodiment uses the electrolyte formulation used in Example 1 as a reference, and the lithium salt content included in the formulation as a variable. The mass fraction of lithium hexafluorophosphate in Example 1 is adjusted to 10%, and the amount of lithium bis(fluorosulfonyl)imide (LiFSi) added is increased to 2%. The rest is the same as in Example 1.

[0057] Example 12 This embodiment uses the electrolyte formulation used in Example 1 as a reference, and the lithium salt content included in the formulation as a variable. The lithium hexafluorophosphate in Example 1 is replaced with lithium difluorosulfonylimide, and the mass fraction is adjusted to 15%. Everything else is the same as in Example 1.

[0058] Example 13 This embodiment uses the electrolyte formulation used in Example 1 as a reference, and the lithium salt additives included in the formulation as variables. The LiODFB in Example 1 is replaced with LiBOB, and the addition amount is 0.5%. Everything else is the same as in Example 1.

[0059] Example 14 This embodiment uses the electrolyte formulation used in Example 1 as a reference, and the lithium salt additives included in the formulation as variables. The LiODFB in Example 1 is replaced with LiPO2F2, and the addition amount is 0.8%. Everything else is the same as in Example 1.

[0060] Example 15 This embodiment provides an electrolyte that differs from Embodiment 1 only in that: functional additive A, as shown in Formula I-3, is added to the electrolyte at a concentration of 1%; functional additive B, as shown in Formula II-3, is added to the electrolyte at a concentration of 0.8%, and the rest is the same as in Embodiment 1.

[0061] Example 16 This embodiment provides an electrolyte that differs from Embodiment 1 only in that the functional additive A, as shown in Formula I-4, is added to the electrolyte at a concentration of 0.3%, while the rest is the same as in Embodiment 1.

[0062] Comparative Example 1 This comparative example provides an electrolyte that differs from Example 1 only in that it does not contain functional additives; otherwise, it is the same as Example 1.

[0063] Comparative Example 2 This comparative example provides an electrolyte that differs from Example 1 only in that it contains only functional additive A, while everything else is the same as in Example 1.

[0064] Comparative Example 3 This comparative example provides an electrolyte that differs from Example 1 only in that it contains only functional additive B, while everything else is the same as Example 1.

[0065] This invention provides an electrochemical device that uses graphite as the negative electrode active material. A negative electrode slurry is prepared by mixing graphite, conductive agent acetylene black, binder CMC, and PAA in a mass percentage ratio of 96.4:0.5:1.0:2.1. The negative electrode slurry is coated onto a copper foil current collector and vacuum dried to obtain a negative electrode sheet. NCM523 is used as the positive electrode active material. A positive electrode slurry is prepared by mixing the positive electrode active material, conductive agent acetylene black, binder PVDF, and CNT in a mass ratio of 97.4:1.0:1.3:0.3. The positive electrode slurry is coated onto an aluminum foil current collector and vacuum dried to obtain a positive electrode sheet. The electrolytes prepared in the examples and comparative examples are then assembled with the above-mentioned positive electrode sheet, negative electrode sheet, and separator to form a pouch battery.

[0066] NCM523 is a typical type of cathode material for ternary lithium-ion batteries, belonging to the lithium nickel cobalt manganese oxide system.

[0067] The electrical performance of the pouch battery was tested, and the results are shown in Table 1.

[0068]

[0069] Comparing Examples 1-14 with Comparative Examples 1-3, it is evident that introducing a combination of functional additives significantly improves high-temperature storage and high-temperature cycling performance. This is primarily because the introduced functional additive molecules synergistically construct a stable and adaptive electrode interface system: the inorganic lithium fluoride and lithium sulfide generated from the decomposition of functional additive A enhance interfacial rigidity and inhibit transition metal dissolution, while the organic network formed by the crosslinking of functional additive B possesses hydrophobic properties to inhibit lithium salt hydrolysis. Together, they construct an "inorganic-organic" hybrid interface, which not only increases the content of inorganic lithium salts in the CEI layer to enhance stability but also balances stability and ion transport efficiency by regulating interfacial conductivity through the organic phase. Furthermore, the decomposition product SO3 of functional additive A... 2-It can form charge-transfer complexes with the acrylate double bonds in functional additive B, reducing the curing initiation temperature and polymerization activation energy of functional additive B, thus facilitating low-temperature in-situ film formation. Simultaneously, the network structure of functional additive B reduces the contact area between the electrolyte and the positive electrode, thereby reducing the decomposition amount of functional additive A. The inorganic lithium salts generated by functional additive A can neutralize acidic substances that may be produced during the polymerization of functional additive B, maintaining electrolyte pH stability and optimizing overall reaction kinetics. Furthermore, when the negative electrode SEI is damaged by lithium dendrite penetration, functional additive A can decompose again in local high-current regions to generate inorganic lithium salts (such as lithium fluoride and lithium sulfide) to fill the defects. When microcracks appear in the positive electrode CEI, the network of functional additive B can repair them through reversible chain segment movement of "de-crosslinking-re-crosslinking." Both of these factors jointly ensure the continuous integrity of the interface during battery cycling, ultimately providing long-life and high-stability interface support for ternary batteries.

[0070] from Figure 1 It can be seen that, compared with Comparative Examples 1, 2, and 3, the DCR growth rate of Examples 1, 3, 5, and 6, which used two functional additives in combination, was significantly lower during high-temperature storage. This is mainly attributed to the synergistic effect of the two functional additives. The functional additives in this application do not act independently of a single functional group, but rather the entire structure produces a multifaceted synergistic effect in the electrolyte. This synergistic effect is key to improving battery performance and stability.

[0071] The high-temperature cycling performance test mentioned above specifically refers to: At 45℃, the test object was charged at a constant current of 1.0C (nominal capacity) to a voltage of 4.25V, then charged at a constant voltage of 4.25V until the current ≤0.05C. After resting for 10 minutes, it was discharged at a constant current of 1C to a cutoff voltage of 2.8V. This constitutes one charge-discharge cycle. The test object was subjected to 500 charge-discharge cycles at 45℃ under the above conditions.

[0072] The capacity retention rate (%) of the test object after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of cycles of the lithium-ion battery.

[0073] The high-temperature storage performance test of lithium-ion batteries is specifically as follows: The lithium-ion battery was charged at a constant current of 1.0C (nominal capacity) to a voltage of 4.25V, then charged at a constant voltage of 4.25V until the current ≤0.05C. After resting for 10 minutes, it was discharged at a constant current of 1C to 2.8V. This constituted one charge-discharge cycle. The tested lithium-ion battery was subjected to three charge-discharge cycles at 25℃ with a charge-discharge rate of 1C, and then fully charged at a 1C rate. The capacity Q0 of the lithium-ion battery was recorded. The fully charged battery was stored at 60℃ for 28 days, and the 1C discharge capacity Q1 of the lithium-ion battery was recorded. Then, the lithium-ion battery was charged and discharged at 25℃ with a 1C rate for 2 weeks, and the 1C discharge capacity Q2 was recorded. The experimental data of high-temperature storage capacity retention rate and capacity recovery rate of the battery were calculated. The calculation formulas used are as follows: Capacity retention rate (%) = Q1 / Q0 × 100%; Capacity recovery rate (%) = Q2 / Q0 × 100%.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. An electrolyte containing functional additives, characterized in that, It includes organic solvents, lithium salts, and electrolyte additives, wherein the electrolyte additives include functional additive A and functional additive B; Based on the total mass of the electrolyte being 100%, functional additive A accounts for 0.3% to 1%, functional additive B accounts for 0.5% to 1%, lithium salt accounts for 10% to 15%, and the remainder is organic solvent; The structural formula of functional additive A is as follows: Wherein, R is selected from substituted or unsubstituted sulfonyl groups, and the substituents are halogens, C2-C3 alkenyl groups, methyl groups, and cyano groups; Functional additive B is selected from at least one of the following structural formulas: 、 、 。 2. The electrolyte containing functional additives according to claim 1, characterized in that, Functional additive A is selected from at least one of the following structural formulas: 、 、 、 、 、 。 3. The electrolyte containing functional additives according to claim 1, characterized in that, The lithium salt is lithium hexafluorophosphate or lithium difluorosulfonylimide.

4. The electrolyte containing functional additives according to claim 1, characterized in that, Electrolyte additives also include sulfur-containing additives, carbonate additives, and lithium salt additives.

5. The electrolyte containing functional additives according to claim 4, characterized in that, By mass percentage, sulfur-containing additives account for 0.5% to 1.5%, carbonate additives account for 0.2% to 0.5%, and lithium salt additives account for 0.5% to 1%.

6. The electrolyte containing functional additives according to claim 4, characterized in that, Sulfur-containing additives include at least one of vinyl sulfate, 1,3-propenesulfonate lactone, and methanedisulfonate. Carbonate additives include ethylene carbonate.

7. The electrolyte containing functional additives according to claim 4, characterized in that, The lithium salt additives include at least one of lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalate)borate, and lithium bis(fluorooxalate)borate.

8. The electrolyte containing functional additives according to claim 1, characterized in that, Organic solvents include cyclic carbonates and chain carbonates. Cyclic carbonates include fluoroethylene carbonate, ethylene carbonate, and propylene carbonate, while chain carbonates include diethyl carbonate and methyl ethyl carbonate.

9. An electrolyte containing functional additives according to claim 8, characterized in that, Based on the total mass of organic solvents being 100%, the total mass of cyclic carbonates is 22%–26%, diethyl carbonate is 10%–20%, and methyl ethyl carbonate is 50%–70%.

10. A lithium-ion battery, comprising a positive electrode and a negative electrode, characterized in that, It also includes the electrolyte as described in any one of claims 1 to 9.

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