High ionic conductivity composite electrolyte for semi-solid lithium batteries and applications thereof

Abstract

This invention relates to a high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries and its application. The composite electrolyte comprises the following components by mass percentage: 2-6% polymeric monomers, 0.1-2% initiator, lithium salt, and 0.5-3% additives, with the balance being solvent. The additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropamide, and mannitol carbonate sulfate is (1-3):(0.8-1.5):(0.5-1.5). The semi-solid-state composite electrolyte of this invention exhibits good stability and few side reactions during in-situ thermosetting, and combines high ionic conductivity with excellent interfacial film-forming properties.

Description

Technical Field

[0001] This invention relates to the field of semi-solid lithium battery technology, specifically to a high ionic conductivity composite electrolyte for semi-solid lithium batteries and its application. Background Technology

[0002] Lithium-ion batteries, as core energy storage devices in the new energy field, are rapidly developing towards higher energy density and higher safety. Semi-solid electrolytes, combining the good wettability of liquid electrolytes with the safety of solid electrolytes, have become a current research hotspot. Among them, in-situ thermal curing technology transforms a liquid precursor containing polymer monomers and initiators into a gel / semi-solid polymer electrolyte inside the battery. This effectively reduces the electrode / electrolyte interface impedance, improves the battery's resistance to leakage and dendrite penetration, and exhibits good compatibility with existing lithium battery production lines.

[0003] Currently, to improve the stability of the negative electrode interface, compounds containing sulfate / sulfonate functional groups are often introduced into the electrolyte as film-forming additives. The SEI film formed by its reduction on the negative electrode surface can inhibit solvent decomposition and improve high-temperature cycling performance. However, existing technologies have the following significant drawbacks: The side reactions during in-situ thermosetting are severe: In-situ thermosetting usually requires maintaining a high temperature of 50~80℃ for several hours to tens of hours. However, traditional sulfate ester compounds have poor kinetic stability in this temperature range and are prone to decomposition and the generation of acidic byproducts. These acidic substances will further catalyze the hydrolysis of fluorinated lithium salts, generating corrosive substances such as hydrofluoric acid (HF), which will aggravate the hydrolysis of lithium salts and the deterioration of the electrolyte system, resulting in a significant increase in the battery's DC internal resistance (DCR) and a decrease in the cycle capacity retention rate at room temperature and high temperature at which the Ii and solvent molecules bind.

[0004] The contradiction between ionic conductivity and interfacial transport kinetics: While in-situ curing with polymer monomers improves mechanical strength, excessively cross-linked polymer networks increase Li... + The tortuosity of transport and the increase of its migration activation energy are affected, and conventional additives are difficult to effectively regulate Li. + The solvation structure results in insufficient bulk ionic conductivity of the semi-solid electrolyte, limiting its rate performance.

[0005] Component compatibility and interfacial film quality issues: SEI films formed by single sulfate ester additives have a high proportion of organic components and insufficient inorganic components, resulting in poor film density and mechanical strength; moreover, in fluorinated lithium salt systems or under high-temperature curing conditions, sulfate esters are prone to excessive decomposition or phase separation with other components, further deteriorating interfacial stability.

[0006] Therefore, there is an urgent need to develop a semi-solid composite electrolyte that exhibits good stability, few side reactions, high ionic conductivity, and excellent interfacial film-forming properties during in-situ thermosetting. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high ionic conductivity composite electrolyte for semi-solid lithium batteries and its application.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a high ionic conductivity composite electrolyte for semi-solid lithium batteries, comprising the following components by mass percentage: 2-6% polymeric monomer, 0.1-2% initiator, lithium salt, and 0.5-3% additives, with the balance being solvent; wherein the additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate is (1-3):(0.8-1.5):(0.5-1.5); and the concentration of the lithium salt is 1-1.5 mol / L.

[0009] This invention employs a ternary additive compound of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate, which has multiple outstanding advantages compared to existing technologies: the three components synergistically regulate the lithium-ion solvation structure to improve the electrolyte's ionic conductivity; the fluoroacrylate participates in polymerization to construct a flexible cross-linked network, weakening the lithium... +The binding forces between the fluoroamide and solvent molecules promote the dissociation of lithium salts, thereby increasing the free lithium ion content in the system. Mannitol carbonate sulfate assists in the full dissociation of lithium salts. Together, these three components form a solvation system with low desolvation energy, effectively accelerating the lithium ion migration rate. Simultaneously, they synergistically suppress side reactions during the in-situ high-temperature curing stage. Mannitol carbonate sulfate can capture acidic HF impurities in the system, blocking the hydrolysis chain reaction induced by PF5. Both fluorinated components are heat-resistant and do not easily decompose to produce acid under high-temperature conditions. The combined use of these three components inhibits lithium salt hydrolysis and degradation from the source, achieving high-temperature aging at 60°C. After 24 hours, the increase in platinum-cobalt color intensity of the electrolyte was extremely low, with no obvious yellowing or discoloration issues, significantly reducing cell solidification and gas generation during cycling. The ternary additives also synergistically construct a low-impedance, highly stable positive and negative electrode composite passivation film. Fluorinated components decompose to generate a highly conductive LiF-based SEI framework, mannitol carbonate sulfate decomposes to produce sulfates that fill the pores of the film layer and improve the toughness of the passivation film. Fluoroamides form a fluorine- and nitrogen-containing composite protective layer on the positive electrode surface, effectively inhibiting the dissolution of transition metals from the positive electrode. The resulting composite SEI / CEI film has low impedance and is less prone to cracking and reconstruction during cycling. Furthermore, the ternary additives synergistically improve the compatibility of the electrolyte system and the wettability of the electrode sheets. Fluoroacrylates and their polymer products have low surface energy, enhancing the electrolyte's wettability on the positive and negative electrodes and the pores of the separator. The combination of the three components balances the overall polarity of the system, eliminates microphase separation defects during the cross-linking process, and ensures continuous and unobstructed ion transport channels within the system.

[0010] Preferably, the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is (1.5-2.5):(0.8-1):(1-1.5).

[0011] Most preferably, the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is 2:0.9:1.3.

[0012] Preferably, the polymerizing monomer is at least one of pentaerythritol tetraacrylate, pentaerythritol triacrylate, and polydipentaerythritol pentaacrylate.

[0013] Preferably, the initiator is at least one selected from azobisisobutyronitrile, dimethyl azobisisobutyrate, and di-tert-butyl azodicarbonate.

[0014] Preferably, the lithium salt is at least one of LiPF6, lithium bis(fluorosulfonyl)imide, LiBF4, and lithium bis(trifluoromethanesulfonyl)imide.

[0015] Preferably, the solvent is diethyl carbonate, ethylene carbonate and methyl ethyl carbonate in a volume ratio of 1:(1-2):(2-3).

[0016] In a second aspect, the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte is a high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries as described in the first aspect.

[0017] Thirdly, the present invention provides a method for preparing the lithium-ion battery of the second aspect, comprising the following steps: The initiator, solvent, lithium salt, and additives in the high ionic conductivity composite electrolyte of the semi-solid lithium battery in the first aspect are mixed evenly and injected into a battery containing a positive electrode, a negative electrode, and a separator. The battery is then encapsulated, placed at 30-40°C for 12-48 hours, and then cured in situ at 50-80°C to obtain the lithium-ion battery.

[0018] Preferably, the in-situ curing time is 12-24 hours, and during the in-situ curing process, 0.5-3 kg / cm² is applied to the battery. 2 The pressure.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a ternary additive compound of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate. This compound synergistically regulates the lithium-ion solvation structure, constructs a low desolvation energy system, and improves ion conductivity and migration rate. It also synergistically suppresses high-temperature curing side reactions, captures HF, blocks the PF5 hydrolysis chain reaction, exhibits extremely low color increase after 24 hours of aging at 60°C, reduces gas production, and synergistically constructs a low-resistance composite SEI / CEI film, inhibiting transition metal dissolution. The electrolyte components of this invention are completely miscible at room temperature without stratification or precipitation. It exhibits good compatibility with the 35°C immersion and resting and 60°C pressurized in-situ curing process. The crosslinking reaction is mild and controllable, requiring no modification to existing semi-solid-state battery production lines, and thus has high industrial application value. Detailed Implementation

[0020] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0021] The raw material information used in the examples and comparative examples is as follows: 1H,1H-perfluoropropyl methacrylate: CAS No. 45115-53-5; N,N-Diethyl-2,3,3,3-Tetrafluoropropionamide: CAS No. 392-63-2; Mannitol sulfate carbonate: CAS number 2520352-94-5; Unless otherwise specified, other materials and reagents used in the examples are commercially available alternatives.

[0022] Example 1 A high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries comprises the following components by mass percentage: 3% polymeric monomer, 0.8% initiator, lithium salt, and 2.1% additives, with the balance being solvent; wherein the additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate is 2:0.9:1.3; the concentration of the lithium salt is 1.3 mol / L; wherein the polymeric monomer is pentaerythritol tetraacrylate, the initiator is dimethyl azobisisobutyrate, the lithium salt is lithium bisfluorosulfonylimide, and the solvent is diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate in a volume ratio of 1:1.5:2.2.

[0023] Example 2 A high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries comprises the following components by mass percentage: 2% polymeric monomer, 0.1% initiator, lithium salt, and 0.5% additives, with the balance being solvent; wherein the additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate is 1:0.8:0.5; the concentration of the lithium salt is 1 mol / L; wherein the polymeric monomer is pentaerythritol tetraacrylate, the initiator is dimethyl azobisisobutyrate, the lithium salt is LiPF6, and the solvent is diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate in a volume ratio of 1:1:2.

[0024] Example 3 A high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries comprises the following components by mass percentage: 6% polymeric monomer, 2% initiator, lithium salt, and 3% additives, with the balance being solvent; wherein the additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate is 3:1.5:1.5; the concentration of the lithium salt is 1.5 mol / L; wherein the polymeric monomer is pentaerythritol tetraacrylate, the initiator is azobisisobutyrate, the lithium salt is lithium difluorosulfonylimide, and the solvent is diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate in a volume ratio of 1:2:3.

[0025] Example 4 The only difference between Example 4 and Example 1 is that the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate in Example 4 is 1.5:0.8:1.

[0026] Example 5 The only difference between Example 5 and Example 1 is that the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate in Example 5 is 2.5:1:1.5.

[0027] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that 1H,1H-perfluoropropyl methacrylate is not added to the additives, and N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate in a molar ratio of 0.9:1.3 are used to make up the missing amount.

[0028] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that N,N-diethyl-2,3,3,3-tetrafluoropropionamide is not added to the additives, and 1H,1H-perfluoropropyl methacrylate and mannitol sulfate in a molar ratio of 2:1.3 are used to make up for the missing amount.

[0029] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that mannitol sulfate carbonate is not added to the additives, and 1H,1H-perfluoropropyl methacrylate and N,N-diethyl-2,3,3,3-tetrafluoropropionamide in a molar ratio of 2:0.9 are used to make up the missing amount.

[0030] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is 0.9:2:1.3.

[0031] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is 1.3:0.9:2.

[0032] Performance testing Test Example 1: Color Changes of Each Electrolyte The initiator, solvent, lithium salt, and additives in the high ionic conductivity composite electrolytes of the semi-solid-state lithium batteries in Examples 1-5 and Comparative Examples 1-5 were mixed evenly and placed in 60°C for 24 hours. The color change of the electrolyte was measured using the national standard GB / T3143-1982, the method for determining the color of liquid chemicals (Hazen units, platinum-cobalt color number). The higher the platinum-cobalt color number, the more severe the yellowing of the electrolyte and the more thermal side reactions; the lower the color number, the less decomposition and color change of the electrolyte and the more stable the system. Specific results are shown in Table 1.

[0033] Table 1 Colorimetric data for each electrolyte Example 1 5 Example 2 25 Example 3 25 Example 4 15 Example 5 15 Comparative Example 1 90 Comparative Example 2 105 Comparative Example 3 125 Comparative Example 4 45 Comparative Example 5 55 Application Example 1-5 and Comparative Application Example 1-5 The lithium-ion batteries in Application Examples 1-5 and Comparative Application Examples 1-5 contain a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte is a high-ionic-conductivity composite electrolyte of the semi-solid-state lithium batteries in Examples 1-5 and Comparative Examples 1-5, respectively. The separator is a commercially available PP / PE separator. The preparation method of the positive electrode sheet is as follows: lithium iron phosphate positive electrode active material, carbon black and PVDF are thoroughly mixed in an appropriate amount of N-methylpyrrolidone at a mass ratio of 96:3:1 to obtain a positive electrode active material slurry; the positive electrode active material slurry is coated on the surface of the positive electrode current collector aluminum foil, and after drying, cold pressing and die cutting, a positive electrode sheet is obtained. The preparation method of the negative electrode sheet is as follows: artificial graphite, acetylene black, and sodium carboxymethyl cellulose are thoroughly stirred in an appropriate amount of deionized water at a mass ratio of 94:3:3 to form a uniform negative electrode active material slurry; the negative electrode active material slurry is coated on the surface of the negative electrode current collector copper foil, and after drying, cold pressing, and die cutting, a negative electrode active material layer is formed on the surface of the copper foil to obtain the negative electrode sheet; The method for preparing the lithium-ion battery includes the following steps: The initiator, solvent, lithium salt, and additives from the high ionic conductivity composite electrolytes of each group of semi-solid lithium batteries were mixed evenly and then injected into batteries containing positive electrodes, negative electrodes, and separators. The mixtures were then encapsulated and left to stand at 35°C for 36 hours. Finally, the mixtures were subjected to a 2 kg / cm² pressure at 60°C. 2 The lithium-ion batteries were obtained by in-situ curing under the specified conditions for 30 hours.

[0034] Test Example 2: Efficiency Test of Each Battery Battery charge-discharge tests were conducted at 25℃ and 45℃, with a voltage range of 2.75-4.25V. The battery was cycled at 1C rate, and the capacity retention after 1000 cycles was tested. The DC internal resistance (DCR) was obtained every 50 cycles by discharging to 50% charge for 30 seconds at 1C. The 1000-cycle DCR growth rate (%) = (DCR of the first cycle after 1000 cycles) / DCR of the first cycle × 100%; the capacity retention rate (%) = (Discharge capacity of the first cycle after 1000 cycles / Discharge capacity of the first cycle) × 100%. The cycle performance results for the battery at 25℃ and 45℃ are shown in Table 2.

[0035] Table 2. Efficiency test results for each battery

[0036] As shown in Table 1-2, combined with the battery test data and electrolyte platinum-cobalt colorimetric results of Application Examples 1-4, it can be seen that when the three additives 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate are compounded simultaneously, and the molar ratio of the three is controlled within the preferred range of 1.5-2.5:0.8-1:1-1.5, the platinum-cobalt colorimetric result of the electrolyte after aging at 60℃ for 24 hours is low, and there are fewer side reactions during the high-temperature curing process. This results in higher capacity retention and lower DCR growth rate of the lithium-ion battery after 1000 cycles at 25℃ and 45℃. This indicates that within this preferred range, the technical effect of stably suppressing high-temperature degradation of the electrolyte and improving the long-cycle performance of the battery can be achieved, and the overall battery performance is better.

[0037] Combining the data from Application Example 1 and Comparative Application Examples 1-3, it can be seen that Comparative Application Example 1 lacks 1H,1H-perfluoropropyl methacrylate, Comparative Application Example 2 lacks N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and Comparative Application Example 3 lacks mannitol carbonate sulfate. After aging at 60℃, the platinum-cobalt color of all three groups of comparative electrolytes increased significantly, indicating that during the 60℃ curing stage, the lithium salt and sulfate components underwent violent hydrolysis side reactions, generating a large amount of corrosive impurities such as HF and PF5. Correspondingly, the capacity retention rate of the lithium-ion battery under 25℃ and 45℃ conditions decreased significantly over 1000 cycles, and the DCR growth rate increased sharply. The performance degradation was further aggravated under the high temperature environment of 45℃. It is evident that 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate ester work synergistically to achieve a comprehensive effect of stabilizing the electrolyte, constructing a low-impedance composite passivation film, and improving ionic conductivity. The simultaneous combination of these three additives is a necessary condition to ensure the excellent cycle performance of the battery.

[0038] Combining the data from Application Example 1 and Comparative Application Examples 4-5, it can be seen that Comparative Application Examples 4 and 5 fully retain the three additives, but the molar ratio of the additives deviates from the range defined in claim 1: 1H,1H-perfluoropropyl methacrylate: N,N-diethyl-2,3,3,3-tetrafluoropropionamide: mannitol carbonate sulfate = (1-3): (0.8-1.5): (0.5-1.5). Compared with the optimal ratio in Application Example 1, it can be seen that the electrolyte in Examples 4-5 shows a significant increase in platinum-cobalt color after standing, indicating a substantial increase in high-temperature curing side reactions. Correspondingly, the capacity retention rate of the lithium-ion battery at 25°C and 45°C per thousand cycles is significantly reduced, and the DCR growth rate is significantly increased. The cycle performance at both room temperature and high temperature is far worse than that of all application examples within the molar ratio range of this invention. The above results indicate that even if all three additives are added, if the molar ratio exceeds the scope of protection of the claims, the components cannot exert a balanced synergistic effect of stabilizing lithium salts, regulating solvation structure, and constructing composite interface films, resulting in a significant deterioration in the thermal stability of the electrolyte and the long-term cycle performance of the battery.

[0039] In summary, the semi-solid composite electrolyte of the present invention has the advantages of good stability and few side reactions during in-situ thermosetting process, and also has high ionic conductivity and excellent interfacial film-forming properties.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-ionic-conductivity composite electrolyte for semi-solid-state lithium batteries, characterized in that, The product comprises the following components by mass percentage: 2-6% monomer, 0.1-2% initiator, lithium salt, and 0.5-3% additives, with the balance being solvent; wherein the additives are 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate; the molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide, and mannitol carbonate sulfate is (1-3):(0.8-1.5):(0.5-1.5); and the concentration of the lithium salt is 1-1.5 mol / L.

2. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is (1.5-2.5):(0.8-1):(1-1.5).

3. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The molar ratio of 1H,1H-perfluoropropyl methacrylate, N,N-diethyl-2,3,3,3-tetrafluoropropionamide and mannitol carbonate sulfate is 2:0.9:1.

3.

4. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The polymer monomer is at least one of pentaerythritol tetraacrylate, pentaerythritol triacrylate, and polydipentaerythritol pentaacrylate.

5. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The initiator is at least one of azobisisobutyronitrile, dimethyl azobisisobutyrate, and di-tert-butyl azodicarbonate.

6. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The lithium salt is at least one of LiPF6, lithium bis(fluorosulfonyl)imide, LiBF4, and lithium bis(trifluoromethanesulfonyl)imide.

7. The high ionic conductivity composite electrolyte for semi-solid-state lithium batteries as described in claim 1, characterized in that, The solvent is diethyl carbonate, ethylene carbonate and methyl ethyl carbonate in a volume ratio of 1:(1-2):(2-3).

8. A lithium-ion battery, characterized in that, It comprises a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte is a high ionic conductivity composite electrolyte for a semi-solid lithium battery as described in any one of claims 1-7.

9. The method for preparing the lithium-ion battery according to claim 8, characterized in that, Includes the following steps: The initiator, solvent, lithium salt, and additives in the high ionic conductivity composite electrolyte of the semi-solid lithium battery as described in any one of claims 1-7 are mixed evenly and injected into a battery containing a positive electrode, a negative electrode, and a separator. The battery is then encapsulated, placed at 30-40°C for 12-48 hours, and then cured in situ at 50-80°C to obtain the lithium-ion battery.

10. The method for preparing a lithium-ion battery as described in claim 9, characterized in that, The in-situ curing time is 12-24 hours. During the in-situ curing process, 0.5-3 kg / cm² is applied to the battery. 2 The pressure.

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