Electrolyte, lithium ion battery and electric equipment

Abstract

The invention relates to an electrolyte, a lithium ion battery and electric equipment. The electrolyte comprises a lithium salt, a complexing agent and a solvent, the complexing agent has a structure as shown in the following formula (1). The electrolyte can effectively improve the high-temperature cycle performance of the battery. Formula (1).

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to an electrolyte, a lithium-ion battery, and an electrical device. Background Technology

[0002] Lithium iron phosphate batteries are favored for their excellent thermal stability and safety, but they often face capacity decay and increased internal resistance when operating in high-temperature environments (such as 60°C and above). Existing technologies mainly focus on adjusting the battery materials and electrolyte formulations. Although these technologies have improved battery performance to some extent, they still have the following drawbacks: (1) limited improvement in capacity retention and internal resistance changes; (2) complex electrolyte preparation processes that increase production costs; and (3) insufficient environmental stability that affects long-term use. Summary of the Invention

[0003] The purpose of this disclosure is to provide an electrolyte, a lithium-ion battery, and an electrical device to effectively improve the high-temperature cycle performance of the battery.

[0004] To address the aforementioned technical problems, the first aspect of this disclosure provides an electrolyte comprising a lithium salt, a complexing agent, and a solvent; the complexing agent having a structure as shown in formula (1): Equation (1); In equation (1), X1 and X2 may be the same or different, and each is independently selected from O, S or N (R7); R4 is selected from substituted or unsubstituted alkylene groups, O, S or N (R8) having 1 to 6 carbon atoms; R1, R2, R3, R5, R6, R7 and R8 may be the same or different, and each is independently selected from hydrogen, deuterium, cyano, halogen group, substituted or unsubstituted alkyl with 1 to 6 carbon atoms, substituted or unsubstituted aryl with 6 to 24 carbon atoms, or substituted or unsubstituted heteroaryl with 3 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; The substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 6 carbon atoms, aryl with 6 to 24 carbon atoms, heteroaryl with 3 to 8 carbon atoms, alkoxy with 1 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative.

[0005] This disclosure provides an electrolyte comprising a complexing agent (acetaminophen ketone derivative) having the structure shown in formula (1). This complexing agent can form a complex with lithium ions on the electrode surface, promoting lithium ion migration and forming a protective film. Using the electrolyte of this disclosure, the capacity retention rate of lithium-ion batteries under high-temperature (e.g., 60°C) cycling can be effectively improved; and the increase in internal resistance at high temperatures can be significantly reduced, ensuring better battery discharge performance. The complexation-adsorption type electrolyte provided by this disclosure has excellent chemical stability at high temperatures, with fewer side reactions occurring during high-temperature cycling, extending the battery's lifespan. Furthermore, the preparation process of the electrolyte provided by this disclosure is relatively simple, requiring no complex additive system, significantly reducing production costs and the difficulty of material preparation.

[0006] In one embodiment, X1 and X2 are 0 in equation (1); R1, R2, R3, R5, R6, R7, and R8 may be the same or different, and each is independently selected from hydrogen, deuterium, cyano, substituted or unsubstituted alkyl with 1 to 5 carbon atoms, substituted or unsubstituted aryl with 6 to 18 carbon atoms, or substituted or unsubstituted heteroaryl with 3 to 6 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; R4 is selected from substituted or unsubstituted alkylene groups or O with 1 to 5 carbon atoms; when the groups of the complexing agent are within the range of this embodiment, better high-temperature cycle performance of the battery can be achieved. In one embodiment, the substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 5 carbon atoms, aryl with 6 to 18 carbon atoms, heteroaryl with 3 to 6 carbon atoms, alkoxy with 1 to 5 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative.

[0007] In one embodiment, in formula (1), R1, R2, R3, R5, R6, R7 and R8 are the same or different, and each is independently selected from hydrogen, methyl, tolyl, pyrrole, furanyl, thiophene, pyrazolyl, imidazolyl, benzofuranyl, benzothiophene, carboxyl, carboxylic acid ester, formaldehyde or acetaldehyde; R4 is selected from methylene or O; when the groups of the complexing agent are within the scope of this embodiment, better high-temperature cycle performance of the battery can be achieved.

[0008] In one embodiment, the complexing agent has a structure as shown in formula (2): Formula (2). This complexing agent can exert a better complexing effect in the electrolyte, thereby further improving the battery capacity and cycle stability.

[0009] In one embodiment, the concentration of the lithium salt in the electrolyte is 0.5~2M, preferably 0.6~1.5M; In one embodiment, the weight ratio of lithium salt to complexing agent is 100:0.02~50, preferably 100:0.05~10. Having the electrolyte composition ratio of this embodiment, especially the preferred composition ratio, can further improve battery performance (e.g., high-temperature cycle performance).

[0010] In one embodiment, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalate borate.

[0011] In one embodiment, the solvent includes a carbonate solvent; In one embodiment, the carbonate solvent includes one or more of dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and fluoroethylene carbonate.

[0012] A second aspect of this disclosure provides a lithium-ion battery including the electrolyte described in the first aspect of this disclosure.

[0013] In one embodiment, the lithium-ion battery further includes a positive electrode and a negative electrode; In one specific embodiment, the positive electrode comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium-rich manganese-based oxide. The negative electrode includes one or more of graphite, oxides, silicon-carbon, silicon-oxygen, and lithium metal.

[0014] A third aspect of this disclosure provides an electrical device including the lithium-ion battery described in the second aspect of this disclosure.

[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0016] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0017] The first aspect of this disclosure provides an electrolyte comprising a lithium salt, a complexing agent, and a solvent; said complexing agent having a structure as shown in formula (1): Equation (1); In equation (1), X1 and X2 may be the same or different, and each is independently selected from O, S or N (R7); R4 is selected from substituted or unsubstituted alkylene groups, O, S or N (R8) having 1 to 6 carbon atoms; R1, R2, R3, R5, R6, R7 and R8 may be the same or different, and each is independently selected from hydrogen, deuterium, cyano, halogen group, substituted or unsubstituted alkyl with 1 to 6 carbon atoms, substituted or unsubstituted aryl with 6 to 24 carbon atoms, or substituted or unsubstituted heteroaryl with 3 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; The substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 6 carbon atoms, aryl with 6 to 24 carbon atoms, heteroaryl with 3 to 8 carbon atoms, alkoxy with 1 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative.

[0018] This disclosure provides an electrolyte comprising a complexing agent (acetaminophen ketone derivative) having the structure shown in formula (1). This complexing agent can form a complex with lithium ions on the electrode surface, promoting lithium ion migration and simultaneously forming a protective film. Using the electrolyte of this disclosure, the capacity retention rate of lithium-ion batteries under high-temperature (e.g., 60°C) cycling can be effectively improved; and the increase in internal resistance at high temperatures can be significantly reduced, ensuring better battery discharge performance. The complexation-adsorption type electrolyte provided by this disclosure exhibits excellent chemical stability at high temperatures, with fewer side reactions occurring during high-temperature cycling, thus extending the battery's lifespan.

[0019] Specifically, the mechanism of action of the complexing agent in the electrolyte provided in this disclosure includes: (1) Complexation effect: The complexing agent increases the stability of lithium ions through coordination with lithium ions, slows down the deposition and precipitation of lithium ions, reduces the rate of phase interface reaction, and thus reduces capacity decay at high temperature. (2) Adsorption effect: The complexing agent forms a protective film on the electrode surface, which effectively slows down the side reactions between the electrode and the electrolyte and extends the service life of the electrode; at the same time, the protective film also enhances the conductivity of the electrolyte. (3) Internal resistance control: After high-temperature aging, compared with traditional electrolytes, complex adsorption electrolytes can significantly reduce the rate of increase in internal resistance, ensuring good cycle performance of the battery at high temperatures.

[0020] In this disclosure, the number of carbon atoms of R1 to R8 and their substituents refers to the total number of carbon atoms of the group and the substituents attached to it.

[0021] In this disclosure, "subunit" refers to a group formed by losing two hydrogen atoms.

[0022] In a preferred embodiment, in formula (1), R1, R2, R3, R5, R6, R7 and R8 are the same or different, and each is independently selected from hydrogen, deuterium, cyano, substituted or unsubstituted alkyl with 1 to 5 carbon atoms, substituted or unsubstituted aryl with 6 to 18 carbon atoms or substituted or unsubstituted heteroaryl with 3 to 6 carbon atoms; R4 is selected from substituted or unsubstituted alkylene groups or O with 1 to 5 carbon atoms; In one specific embodiment, the substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 5 carbon atoms, aryl with 6 to 18 carbon atoms, heteroaryl with 3 to 6 carbon atoms, alkoxy with 1 to 5 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative.

[0023] In one specific embodiment, the substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from fluorine, chlorine, nitroso, methyl, methoxy, pyrrole, furanyl, carboxyl, carboxylic acid ester, formaldehyde, and acetaldehyde.

[0024] In one specific embodiment, in formula (1), R1, R2, R3, R4, R5, R6 and R7 are the same or different, and each is independently selected from hydrogen, methyl, toluene, pyrrole, furanyl, thiophene, pyrazolyl, imidazolyl, benzofuranyl, benzothiophene, carboxyl, carboxylic acid ester, formaldehyde, acetaldehyde; R4 is selected from methylene or O.

[0025] In a preferred embodiment, X1 and X2 are 0 in formula (1).

[0026] In a preferred embodiment, the complexing agent has a structure as shown in formula (2): Formula (2); wherein R4 includes, but is not limited to, methylene, O, etc.; this complexing agent can exert a better complexing effect in the electrolyte to further improve the battery capacity and cycle stability.

[0027] In one embodiment, the concentration of the lithium salt in the electrolyte is 0.5~2M, preferably 0.6~1.5M; Optionally, the weight ratio of lithium salt to complexing agent is 100:0.1~50, preferably 100:0.05~10. Having the electrolyte composition ratio of this embodiment, especially the preferred composition ratio, can further improve battery performance (e.g., high-temperature cycle performance).

[0028] In this disclosure, the complexing agent can be purchased through ordinary channels or prepared by known methods.

[0029] In one specific embodiment, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorosulfonylimide, and lithium difluorooxalate borate; preferably lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium difluorosulfonylimide.

[0030] In one embodiment, the solvent includes a carbonate solvent.

[0031] In one specific embodiment, the carbonate solvent includes one or more of dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and fluoroethylene carbonate; preferably, it includes one or more of dimethyl carbonate, ethylene carbonate, and propylene carbonate.

[0032] In one specific embodiment, the electrolyte is prepared by a method comprising the following steps: (a) Under a protective atmosphere, lithium salt is added to a solvent for a first mixing to obtain a first mixture; (b) The complexing agent is gradually added to the first mixture, and a second mixing is carried out until the complexing agent is completely dissolved to obtain a second mixture; (c) The second mixture is subjected to vacuum degassing to remove air bubbles from the solvent, thereby improving the stability of the electrolyte. The electrolyte preparation process provided in this disclosure is relatively simple, requiring no complex additive system, which significantly reduces production costs and the difficulty of material preparation. In one specific embodiment, the conditions for the first mixing include: a temperature of 25~45℃ and a time of 2~8h; preferably, a temperature of 25~40℃ and a time of 2~6h; the conditions for the second mixing include: a temperature of 25~60℃ and a time of 1~7h; preferably, a temperature of 25~50℃ and a time of 1~6h.

[0033] In one specific embodiment, the protective atmosphere includes one or more of nitrogen, argon, and a hydrogen-argon mixture, preferably a hydrogen-argon mixture; and the water content is less than 1 ppm (i.e., anhydrous conditions).

[0034] A second aspect of this disclosure provides a lithium-ion battery including the electrolyte described in the first aspect of this disclosure.

[0035] In one embodiment, the lithium-ion battery further includes a positive electrode and a negative electrode; Optionally, the positive electrode comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium-rich manganese-based oxide; The negative electrode includes one or more of graphite, oxides, silicon-carbon, silicon-oxygen, and lithium metal.

[0036] The lithium-ion battery disclosed herein exhibits higher high-temperature cycle capacity retention (e.g., after 200 cycles at 60°C, the capacity retention reaches over 90%, while existing lithium-ion batteries typically retain only 70-80%). The internal resistance of the battery disclosed herein increases from an initial value of 5 mΩ to 12 mΩ, with the growth rate decreasing to 40%, while the internal resistance growth rate in existing batteries is often higher than 50%. This disclosure significantly reduces the increase in internal resistance at high temperatures, ensuring better battery discharge performance. The battery disclosed herein also exhibits superior environmental stability and a longer service life.

[0037] The lithium-ion battery disclosed herein can be prepared and assembled using conventional methods. Specifically, the battery of this disclosure can be in the form of a battery cell, a battery module, or a battery pack. A battery cell includes a casing, an electrode core, and an electrolyte. The casing forms a receiving space, and the electrode core and electrolyte are disposed within the receiving space. The electrode core can include a positive electrode, a negative electrode, and a separator, which are arranged in a stacked or wound manner. In some embodiments, battery cells can be assembled into a battery module, and the number of battery cells contained in a battery module can be one or more, the specific number of which can be selected by those skilled in the art based on the application and capacity of the battery module. In some embodiments, battery modules can also be assembled into a battery pack, and the number of battery modules contained in a battery pack can be one or more, the specific number of which can be selected by those skilled in the art based on the application and capacity of the battery pack. The positive electrode, electrolyte, and separator of the battery of this disclosure can be of conventional types in the art.

[0038] A third aspect of this disclosure provides an electrical device including the lithium-ion battery described in the second aspect of this disclosure.

[0039] In this disclosure, the electrical equipment can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, and electric toy, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.

[0040] In a preferred embodiment, the electrical equipment includes, but is not limited to, vehicles, mobile phones, portable devices, laptops, and spacecraft.

[0041] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0042] Example 1 (1) Preparation of electrolyte Solvent: A mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1; Lithium salt: Lithium hexafluorophosphate (LiPF6) with a concentration of 1M is used.

[0043] Complexing agent: Selected as a complexing agent for acetaminophen derivatives (structural formula is...) The amount added is 5% by weight of the lithium salt, that is, the weight ratio of lithium salt to complexing agent is 100:5.

[0044] Electrolyte preparation methods include: (1-1) In an anhydrous nitrogen atmosphere, EC and DMC are mixed in a reaction vessel; Slowly add the lithium salt (LiPF6) to the mixed solvent and stir until homogeneous (first mixing, temperature 25℃, time 2h) to ensure that the lithium salt is fully dissolved.

[0045] (1-2) Gradually add the complexing agent and continue stirring for 30 minutes under stirring conditions (second mixing, temperature 30℃, time 2h) until the complexing agent is completely dissolved.

[0046] (1-3) The prepared electrolyte is degassed using a vacuum degassing device.

[0047] (2) Preparation of positive electrode sheet Lithium iron phosphate (LiFePO4) was used as the positive electrode active material, mixed with a positive electrode conductive agent (carbon black) and a positive electrode binder (polytetrafluoroethylene), and N-methylpyrrolidone was used as a solvent to prepare a positive electrode coating slurry. The positive electrode coating slurry contained 97% by weight of lithium iron phosphate, 1.5% by weight of carbon black, and 1.5% by weight of polytetrafluoroethylene. The mixed positive electrode slurry was coated onto aluminum foil using a scraping method, and then dried at 60°C to remove the solvent, thus obtaining a positive electrode sheet (80 μm thick).

[0048] (3) Preparation of negative electrode sheet Graphite was used as the negative electrode active material, mixed with a negative electrode conductive agent (Super P) and a negative electrode binder (sodium carboxymethyl cellulose), and deionized water was used as the solvent to prepare a negative electrode coating slurry. The negative electrode coating slurry contained 97% by weight of graphite, 1.5% by weight of the negative electrode conductive agent, and 1.5% by weight of the negative electrode binder. The mixed negative electrode slurry was coated onto copper foil using a scraping method, and then dried at 60°C to remove the solvent, thus obtaining a negative electrode sheet (60 μm thick).

[0049] (4) Battery assembly In a dust-free, water-free, and dry environment, the positive electrode, separator (made of polyethylene) and negative electrode are stacked to form a battery structure.

[0050] The electrode material is completely impregnated with the complex adsorption electrolyte prepared in step (1), wherein the weight ratio of the battery structure to the electrolyte is 1:0.02.

[0051] The assembled battery is encapsulated in a soft-pack casing, and excess air is expelled to form a sealed battery cell.

[0052] Comparative Example 1 This comparative example refers to the battery preparation method in Example 1, but differs from Example 1 in that: The complex adsorption electrolyte was replaced with a conventional electrolyte, which consisted of 1M LiPF6 and a solvent of DMC (dimethyl carbonate):EC (ethylene carbonate) = 1:1 (volume ratio); the rest of the process was the same as in Example 1.

[0053] Example 2 This embodiment refers to the battery preparation method in Embodiment 1, but differs from Embodiment 1 in that: Replace the complexing agent with The remaining process is the same as in Example 1.

[0054] Example 3 This embodiment refers to the battery preparation method in Embodiment 1, but differs from Embodiment 1 in that: The weight ratio of lithium salt to complexing agent in the electrolyte is 100:15. The remaining process is the same as in Example 1.

[0055] Test case This test example is used to perform performance testing on the batteries prepared in the above embodiments and comparative examples: (1) Performance test settings The assembled battery was subjected to charge-discharge cycle tests in a constant temperature chamber at 60℃, with charging and discharging currents of 1C and 1C (i.e., 1 times the capacity), respectively, to simulate actual working conditions.

[0056] (2) Performance monitoring Record the battery capacity (Ah) and internal resistance (Ω) after each charge and discharge cycle, and test the battery internal resistance using electrochemical impedance spectroscopy (EIS).

[0057] Internal resistance and capacity were tested every 10 cycles to monitor their changes with the number of cycles.

[0058] (3) Data Analysis The improvement effect was evaluated by comparing the cumulative cycle performance data, internal resistance change statistics, and capacity retention of the batteries obtained from the above embodiments and comparative examples. The test results are listed in Table 1 below.

[0059] Table 1

[0060] The data in Table 1 shows that: Comparative Example 1 uses a conventional electrolyte, while Examples 1-3 use the electrolyte containing a complexing agent provided in this disclosure. Compared with Comparative Example 1, the batteries of Examples 1-3 have higher initial efficiency, higher capacity retention after 200 cycles, lower internal resistance after 200 cycles, and require more cycles for the battery to have 80% SOH remaining. This shows that adding a complexing agent to the electrolyte provided in this disclosure can significantly improve battery performance. Comparing Example 1 and Example 3, it can be seen that in the electrolyte of Example 1, the weight ratio of lithium salt to complexing agent is within the preferred range of this disclosure. The battery in Example 1 has a higher initial efficiency and a capacity retention rate after 200 cycles, a lower internal resistance after 200 cycles, and requires more cycles for the battery to have 80% SOH remaining. This indicates that the electrolyte of Example 1 has better performance.

[0061] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0063] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An electrolyte, characterized in that, It includes a lithium salt, a complexing agent, and a solvent; the complexing agent has a structure as shown in formula (1): Equation (1); In equation (1), X1 and X2 may be the same or different, and each is independently selected from O, S or N (R7); R4 is selected from substituted or unsubstituted alkylene groups, O, S or N (R8) having 1 to 6 carbon atoms; R1, R2, R3, R5, R6, R7 and R8 may be the same or different, and each is independently selected from hydrogen, deuterium, cyano, halogen group, substituted or unsubstituted alkyl with 1 to 6 carbon atoms, substituted or unsubstituted aryl with 6 to 24 carbon atoms, or substituted or unsubstituted heteroaryl with 3 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; The substituents in R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 6 carbon atoms, aryl with 6 to 24 carbon atoms, heteroaryl with 3 to 8 carbon atoms, alkoxy with 1 to 8 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative.

2. The electrolyte according to claim 1, characterized in that, In the formula (1), R1, R2, R3, R5, R6, R7 and R8 are the same or different, and each is independently selected from hydrogen, deuterium, cyano, substituted or unsubstituted alkyl with 1 to 5 carbon atoms, substituted or unsubstituted aryl with 6 to 18 carbon atoms, or substituted or unsubstituted heteroaryl with 3 to 6 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; Optionally, R4 is selected from substituted or unsubstituted alkylene groups or O having 1 to 5 carbon atoms; Optionally, the substituents in R1, R2, R3, R4, R5, R6, R7 and R8 may be the same or different, and each may be independently selected from deuterium, cyano, halogen group, nitroso, alkyl with 1 to 5 carbon atoms, aryl with 6 to 18 carbon atoms, heteroaryl with 3 to 6 carbon atoms, alkoxy with 1 to 5 carbon atoms, carboxyl or its ester derivative or its amide derivative, hydroxyl or its ether derivative or its ester derivative, aldehyde or its acetal derivative; Optionally, X1 and X2 are 0.

3. The electrolyte according to claim 1, characterized in that, In the formula (1), R1, R2, R3, R5, R6, R7 and R8 are the same or different, and each is independently selected from hydrogen, methyl, tolyl, pyrrole, furanyl, thiophene, pyrazolyl, imidazolyl, benzofuranyl, benzothiophene, carboxyl, carboxylic acid ester, formaldehyde or acetaldehyde; R4 is selected from methylene or O.

4. The electrolyte according to claim 1, characterized in that, The complexing agent has a structure as shown in formula (2): Equation (2).

5. The electrolyte according to claim 1, characterized in that, In the electrolyte, the concentration of the lithium salt is 0.5~2M, preferably 0.6~1.5M; Optionally, the weight ratio of lithium salt to complexing agent is 100:0.02~50, preferably 100:0.05~10.

6. The electrolyte according to claim 1, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorosulfonylimide, and lithium difluorooxalate borate.

7. The electrolyte according to claim 1, characterized in that, The solvent includes carbonate solvents; Optionally, the carbonate solvent includes one or more of dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and fluoroethylene carbonate.

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

9. The lithium-ion battery according to claim 8, characterized in that, The lithium-ion battery also includes a positive electrode and a negative electrode; Optionally, the positive electrode comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium-rich manganese-based oxide; The negative electrode includes one or more of graphite, oxides, silicon-carbon, silicon-oxygen, and lithium metal.

10. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 8 or 9.

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