A method for preparing a polymer solid-state electrolyte with a positive charge group, a solid-state electrolyte, and applications thereof

Abstract

This invention discloses a method for preparing a polymer solid electrolyte with positively charged groups, comprising: S1. mixing polymer monomers, initiators, polymerizable ionic liquids, and lithium salts, and stirring to obtain a uniform solution; the lithium salt concentration in the solution is in the range of 0.1–10 M, and the mass percentage of the polymerizable ionic liquid is 0.01%–20%; S2. casting the solution onto a foil and solidifying it to form a solid electrolyte, or directly assembling it in situ into a battery in the solution state, and finally heating it at high temperature to solidify it to form a solid electrolyte. This invention utilizes the excellent wettability of the polymer monomers and the precursor liquid of the cationic polymerizable ionic liquid, combined with in-situ polymerization technology, to deeply penetrate into the pores of the high-load positive electrode, thereby constructing a continuous and efficient ion transport network, significantly reducing interfacial impedance, and improving the coulombic efficiency and cycle life of the solid-state battery. The overall process is simple, easy to operate, and highly compatible with existing processes.

Description

Technical Field

[0001] This invention belongs to the field of solid-state lithium-ion battery technology, specifically relating to a method for preparing a polymer solid electrolyte with positively charged groups, the solid electrolyte and its applications. Background Technology

[0002] As electric vehicles and portable electronic devices increasingly demand higher energy density and safety, traditional liquid lithium-ion batteries pose serious safety hazards such as fire and explosion due to their use of flammable organic electrolytes. Solid-state lithium-ion batteries (SSBs) use non-flammable solid electrolytes to replace liquid electrolytes and separators, which not only fundamentally improves safety but also allows for compatibility with high-voltage positive electrodes and metallic lithium negative electrodes. Therefore, they are widely regarded as the ideal choice for next-generation high-energy-density energy storage systems.

[0003] Among various solid electrolytes, polymer solid electrolytes exhibit the most promising industrialization prospects due to their advantages such as light weight, low cost, good viscoelasticity, and ease of processing and molding. However, their insufficient ionic conductivity has become a key bottleneck restricting performance release. Low ionic conductivity under high load conditions can trigger a series of cascading failure phenomena: First, the slow ion transport is difficult to match the high-rate Li+ insertion / extraction kinetics at the electrode interface, leading to severe concentration polarization and voltage hysteresis, especially causing rapid capacity decay at high rates; second, Li... + Insufficient supply exacerbates interfacial side reactions, leading to continuous thickening and uneven distribution of the solid electrolyte interphase (SEI) film, creating a vicious cycle of "low conductivity → high polarization → SEI proliferation → increased impedance." Furthermore, impaired longitudinal ion transport causes uneven Li+ deposition within high-load electrodes, resulting in stress mismatch and contact failure in localized areas of the active particles. These problems severely restrict the effective utilization of active materials, making it difficult for high-energy-density solid-state batteries to achieve long-cycle stability.

[0004] In conclusion, overcoming the bottleneck of polymer electrolyte ionic conductivity has become a key step in promoting the practical application of high-energy-density solid-state batteries. Summary of the Invention

[0005] The purpose of this application is to overcome the above-mentioned shortcomings of the prior art and provide a method for preparing a polymer solid electrolyte with positively charged groups. By adding a polymerizable ionic liquid to the polymer electrolyte and using in-situ polymerization, a continuous and efficient ion transport network is constructed, which significantly reduces interfacial impedance and improves the coulombic efficiency and cycle life of solid-state batteries.

[0006] To achieve the above-mentioned objectives, this application provides a method for preparing a polymer solid electrolyte with positively charged groups, comprising the following steps: S1. The polymer monomer, initiator, polymerizable ionic liquid, and lithium salt are mixed and stirred until homogeneous to obtain a solution; the cation in the selected polymerizable ionic liquid is one or more of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide, methacryloyloxyethyltrimethylammonium, [2-(vinyloxy)ethyl]trimethylammonium, and diallyl dimethylammonium; in the solution, the lithium salt concentration ranges from 0.1 to 10 M, and the mass percentage of the polymerizable ionic liquid is from 0.01% to 0.65%; S2. The above solution is poured onto the foil and solidified to form a solid electrolyte, or it is directly assembled into the battery in situ using the solution state, and finally solidified by high temperature heating to form a solid electrolyte.

[0007] This invention incorporates cations (i.e., the cationic portion of the polymeric ionic liquid) into a polymer solid electrolyte and employs an in-situ polymerization method. The ionic liquid tends to accumulate at the interface between the electrolyte and the electrode, effectively reducing interfacial tension and ensuring that the precursor solution completely wets the cathode particles before polymerization, while simultaneously forming a stable interfacial layer after polymerization. Furthermore, a small amount of ionic liquid is embedded in the polymer chains, essentially introducing "ionic nodes" into the polymer network. These nodes disrupt the regular arrangement of the polymer chains, increasing chain flexibility and thus improving ionic conductivity. Therefore, this invention essentially introduces "built-in ion transport promoters" and "interfacial stabilizers" into the polymer matrix, providing more free ions and inhibiting anion migration, thus solving the "low conductivity" problem. Simultaneously, it improves wettability and constructs a stable high-voltage interfacial film, resolving the problems of "interfacial side reactions" and "SEI proliferation."

[0008] Preferably, in S1, the selected polymer monomer is vinylene carbonate, and the selected lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorophosphate, and lithium hexafluoroarsenate. After polymerization, vinylene carbonate (VC) forms a stable, dense, and flexible polymer matrix, which helps to construct a good electrode / electrolyte interface.

[0009] Preferably, in S1, the selected initiator is one or more of the following: dimethyl azobisisobutyrate, 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), benzoyl peroxide, lithium phenyl-2,4,6-trimethylbenzoylphosphonate, lauroyl peroxide, and azobisisobutyronitrile.

[0010] Preferably, in the solution, the lithium salt concentration ranges from 1 to 5 M, and the mass percentage of the polymerizable ionic liquid is 0.01% to 0.35%. More preferably, in the solution, the lithium salt concentration ranges from 1 to 4 M, and the mass percentage of the polymerizable ionic liquid is 0.01% to 0.15%. This invention adjusts the lithium salt concentration and the mass percentage of the polymerizable ionic liquid to achieve a high polymerization conversion rate, near-complete polymerization and fixation of the ionic liquid, while not damaging the mechanical strength and processing fluidity of the main polymer, and enabling the formation of a stable interface layer after polymerization.

[0011] Preferably, in step S2, the material is cast onto a foil and cured at a temperature range of 25-110°C. The curing temperature can be flexibly adjusted according to different polymer systems and solvent evaporation requirements without significant modifications to the production line.

[0012] Preferably, in S2, the amount of solution used in the in-situ assembly of the battery is 0.5–4 g / Ah. The specific operation of the in-situ polymerization is as follows: under vacuum conditions of ≤2000 Pa, the polymerization reaction is carried out at 60–120°C for 8–48 h. This invention precisely controls the matching of electrolyte and active material, taking into account both wettability and energy density; setting vacuum conditions (≤2000 Pa) can remove bubbles and residual gases, and assist in solvent removal; setting a wide temperature range allows for flexible selection of polymerization temperature according to different monomer systems and initiator activities, and can also adopt stepwise heating (first low-temperature prepolymerization and shaping, then high-temperature full polymerization) to optimize the polymer network structure.

[0013] Preferably, in S2, the positive electrode active material is one of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, or lithium nickel cobalt aluminum oxide, which is assembled in situ into the battery. Solid electrolytes with positively charged groups have the advantage of a wide voltage window, which can fully release the high voltage potential of lithium cobalt oxide and lithium nickel manganese oxide; while their high safety and ability to suppress side reactions can significantly compensate for the balance requirements of high-nickel ternary (NCM / NCA) and lithium iron phosphate in terms of interface stability or energy density.

[0014] This invention also provides a solid electrolyte obtained by the method for preparing the polymer solid electrolyte with positively charged groups. It is particularly suitable for applications requiring high safety and rate performance, such as high-energy-density lithium metal batteries, high-voltage solid-state batteries, and flexible / wearable energy storage devices.

[0015] The present invention also provides the application of the preparation method of the polymer solid electrolyte with positively charged groups in lithium-ion batteries.

[0016] Compared with the prior art, the present invention has the following technical effects: 1. This invention utilizes the excellent wettability of vinylene carbonate (VC) and the precursor liquid of cationic polymerizable ionic liquid, combined with in-situ polymerization technology, to deeply penetrate into the pores of the high-load cathode, thereby constructing a continuous and efficient ion transport network, significantly reducing interfacial impedance, and improving the coulombic efficiency and cycle life of solid-state batteries.

[0017] 2. This invention optimizes the dosage of each component in the solid electrolyte, adjusts the concentration of lithium salt and the mass percentage of polymerizable ionic liquid, so that the polymerizable ionic liquid has a high polymerization conversion rate, the ionic liquid is basically completely polymerized and fixed, and at the same time, it does not damage the mechanical strength and processing fluidity of the main polymer, and a stable interface layer is formed after polymerization.

[0018] 3. The overall process of this invention is simple and easy to operate, requiring no special or complex dedicated equipment, and is highly compatible with existing mature lithium battery manufacturing systems. This design significantly reduces the technical barriers and equipment investment costs for the transformation of solid-state batteries from laboratory research and development to large-scale production, effectively promoting the industrialization of solid-state batteries. Attached Figure Description

[0019] Figure 1 These are comparative photographs showing the polymerization states of different electrolytes in this invention. Figure 2 The cycling performance curves of lithium metal symmetric batteries in Example 15 and Comparative Example 3 are shown. Figure 3 These are scanning electron microscope images of the lithium metal surface after cycling in Example 15 and Comparative Example 3; Figure 4 The images show the long-cycle performance curves of lithium iron phosphate batteries in Example 15 and Comparative Example 3. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0021] In the following description, the embodiments of this application are for illustrative purposes and not for limiting purposes, so as to provide a thorough understanding of the embodiments. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known preparation methods have been omitted so as not to obscure the description of the embodiments of this application with unnecessary details. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available.

[0022] It should also be understood that the terms “including,” “comprising,” “having,” and their variations all mean “including but not limited to,” unless otherwise specifically emphasized. “Multiple” means two or more.

[0023] This section only introduces content related to the inventive points; other details can be obtained from relevant technologies and will not be described in detail here. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0024] The specific implementation method is as follows: Example 1: The preparation of a polymer solid electrolyte with positively charged groups includes the following steps: (1) In a glove box filled with argon (water and oxygen content are both below 0.1 ppm), take an appropriate amount of vinylene carbonate (VC) as a polymer monomer; (2) Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to the VC monomer and stir until completely dissolved to prepare a lithium salt solution with a concentration of 2 M; (3) Add 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt to the above solution at a concentration of 2 mg / ml (based on the volume of the lithium salt solution), corresponding to a mass fraction of approximately 0.14 wt%. (4) Finally, add the initiator azobisisobutyronitrile (AIBN). The amount of initiator added is 0.1 wt% of the total mass of the monomer and ionic liquid. Stir and mix thoroughly to obtain a transparent polymer electrolyte precursor solution with positively charged groups. (5) Add a polymer electrolyte precursor solution with positively charged groups to a depth of 0.03 cm and an area of ​​1.13 cm². 2 The precursor solution was cured by heating the polytetrafluoroethylene mold in a 60℃ oven for 24 h to obtain a polymer solid electrolyte. (6) Using Swagelok batteries, the EIS test was performed, and the ionic conductivity at 30°C was measured to be 1.57 mS / cm.

[0025] Example 2: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 0.1 mg / ml (based on the volume of lithium salt solution); the rest of the settings were the same as in Example 1. An EIS test was performed using a Swagelok battery, and the ionic conductivity at 30°C was measured to be 0.71 mS / cm.

[0026] Example 3: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 0.5 mg / ml (based on the volume of lithium salt solution); the rest of the settings were the same as in Example 1. An EIS test was performed using a Swagelok battery, and the ionic conductivity at 30°C was measured to be 0.84 mS / cm.

[0027] Example 4: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 1 mg / ml (based on the volume of the lithium salt solution); the rest of the settings were the same as in Example 1. An EIS test was performed using a Swagelok battery, and the ionic conductivity at 30°C was measured to be 1.26 mS / cm.

[0028] Example 5: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 5 mg / ml (based on the volume of the lithium salt solution); the rest of the settings were the same as in Example 1. The system failed to complete polymerization.

[0029] Example 6: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 10 mg / ml (based on the volume of the lithium salt solution); the rest of the settings were the same as in Example 1. The system failed to complete polymerization.

[0030] Example 7: Compared with Example 1, in step (3) of this example, the amount of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt added was 20 mg / ml (based on the volume of the lithium salt solution); the rest of the settings were the same as in Example 1. The system failed to complete polymerization.

[0031] Example 8: Compared with Example 5, in step (4) of this example, the initiator azobisisobutyronitrile (AIBN) was added to the mixture at 0.5 wt%; the rest of the settings were the same as in Example 1. An EIS test was performed using a Swagelok battery, and the ionic conductivity at 30°C was measured to be 1.35 mS / cm.

[0032] Example 9: Compared with Example 6, in this example, the initiator azobisisobutyronitrile (AIBN) was added to the mixture at 0.5 wt% in step (4); the remaining settings were the same as in Example 1. The system failed to complete polymerization.

[0033] Example 10: Compared with Example 1, in this example, step (3) involves adding 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt at a rate of 15 mg / ml (based on the lithium salt solution volume); step (4) involves adding the initiator azobisisobutyronitrile (AIBN) at a rate of 1 wt% to the mixture; the remaining settings are the same as in Example 1. This system failed to complete polymerization.

[0034] Example 11: Compared with Example 7, in step (4) of this example, the initiator azobisisobutyronitrile (AIBN) was added to the mixture at 1 wt%; the remaining settings were the same as in Example 1. The system failed to complete polymerization.

[0035] Example 12: Compared with Example 1, the lithium salt added in step (2) of this example is lithium bisfluorosulfonylimide (LiFSI); the rest of the settings are the same as in Example 1. Using a Swagelok battery, an EIS test was performed, and the ionic conductivity at 30 °C was measured to be 1.22 mS / cm.

[0036] Example 13: Compared with Example 1, the lithium salt added in step (2) of this example is lithium hexafluorophosphate (LiPF6); the rest of the settings are the same as in Example 1. Using a Swagelok battery, an EIS test was performed, and the ionic conductivity at 30 °C was measured to be 1.13 mS / cm.

[0037] Example 14: Compared with Example 1, the lithium salt concentration added in step (2) of this example is 1 M; the rest of the settings are the same as in Example 1. Using a Swagelok battery, an EIS test was performed, and the ionic conductivity at 30 °C was measured to be 1.28 mS / cm.

[0038] Example 15: Compared with Example 1, the lithium salt concentration added in step (2) of this example is 4 M; the rest of the settings are the same as in Example 1. Using a Swagelok battery, an EIS test was performed, and the ionic conductivity at 30 °C was measured to be 2.43 mS / cm.

[0039] Example 16: Compared with Example 1, the lithium salt concentration added in step (2) of this example is 10 M; the rest of the settings are the same as in Example 1. The lithium salt in this system did not completely dissolve.

[0040] Comparative Example 1: (1) In a glove box filled with argon (water and oxygen content are both below 0.1 ppm), take an appropriate amount of vinylene carbonate (VC) as a polymer monomer; (2) Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to the VC monomer and stir until completely dissolved to prepare a lithium salt solution with a concentration of 2 M; (3) Finally, add the initiator azobisisobutyronitrile (AIBN). The amount of initiator added is 0.1 wt% of the total mass of the monomer and ionic liquid. Stir and mix thoroughly to obtain a transparent polymer electrolyte precursor solution. (4) The polymer electrolyte precursor solution was added to a polytetrafluoroethylene mold with a depth of 0.03 cm and an area of ​​1.13 cm2, and the precursor solution was cured by heating in an oven at 60 ℃ for 8 h to obtain a polymer solid electrolyte. (5) Using Swagelok batteries, the EIS test was performed, and the ionic conductivity at 30 °C was measured to be 0.67 mS / cm.

[0041] Comparative Example 2: Compared with Comparative Example 1, the lithium salt concentration added in step (2) of this comparative example is 1 M; the other settings are the same as those in Comparative Example 1. Using Swagelok batteries, EIS testing was performed, and the ionic conductivity at 30 °C was measured to be 0.32 mS / cm.

[0042] Comparative Example 3: Compared with Comparative Example 1, the lithium salt concentration added in step (2) of this comparative example is 4 M; the other settings are the same as those in Comparative Example 1. Using Swagelok batteries, EIS testing was performed, and the ionic conductivity at 30 °C was measured to be 0.84 mS / cm.

[0043] Performance testing: The ionic conductivity described in this invention is obtained by the following test methods: The ionic conductivity of solid polymer electrolytes was tested using electrochemical impedance spectroscopy (EIS). A solid polymer electrolyte membrane was sandwiched between two symmetrical stainless steel electrodes, and the impedance of the corresponding solid electrolyte was measured using a Swagelok cell. The formula for calculating conductivity is as follows: Where L is the thickness of the polymer electrolyte, S is the area of ​​the polymer electrolyte, and R is the impedance obtained from the EIS test. The test results are shown in Table 1.

[0044] The long-cycle performance of the lithium metal battery of this invention was obtained by the following test methods: The battery assembly and testing are carried out according to the following steps: (1) The positive electrode material uses lithium iron phosphate active material. The active material, conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 9:0.5:0.5, coated on carbon-coated aluminum foil with a 50μm doctor blade, and cut into electrode sheets after drying.

[0045] (2) The negative electrode material is lithium metal. The battery is assembled using CR2025 coin cells. The corresponding coin cells are obtained by combining and packaging the positive electrode, electrolyte film, and negative electrode in that order.

[0046] The performance and assembly methods of lithium metal symmetric batteries are the same, and the electrodes are all lithium metal.

[0047] Table 1. Statistics on the polymerization state and ionic conductivity of electrolytes The optical images of the characteristic groups in Table 1 above are as follows: Figure 1 As shown.

[0048] Comparative examples and comparative examples show that introducing ionic liquids can improve the ionic conductivity of polyvinyl carbonate-based solid electrolytes (Examples 1-4), but excessively high ionic liquid concentrations prevent polyvinyl carbonate from polymerizing (Examples 5-7). Increasing the initiator concentration allows polymerization at higher ionic liquid concentrations, but polymerization still fails at concentrations exceeding 10 mg / ml (Examples 8-11). After replacing the lithium salt with other examples, the ionic conductivity of all examples was lower than that of Example 1 (Examples 12-13). Salt concentration control shows that the ionic conductivity of the polymer electrolyte increases with increasing concentration (Examples 14-15), but excessively high salt concentrations prevent complete dissolution of the VC solvent (Example 16).

[0049] Example 15 and Comparative Example 3 achieved the best ionic conductivity, and subsequent performance tests were conducted using these two groups.

[0050] like Figure 2 The figure shows the cycle performance of lithium metal symmetric batteries in Example 15 and Comparative Example 3, tested under the condition of 0.5 mA cm⁻¹. -2 A 1-hour charge / discharge cycle was performed at a current density. Example 15 achieved stable cycling for over 2500 hours in this test, while Comparative Example 3 exhibited a short circuit after 510 hours of cycling. This result fully demonstrates the stability of the polymer electrolyte with positively charged groups on the lithium metal electrode. The cycled battery was disassembled, and the lithium metal electrode was subjected to scanning electron microscopy (SEM) testing; the results are as follows... Figure 3 As shown, in Comparative Example 3, cracks appeared on the lithium metal surface, and obvious needle-like morphology was observed. In Example 15, which exhibited better long-cycle performance, the surface morphology was smooth, the deposited lithium was more uniform, and no needle-like morphology was observed.

[0051] like Figure 4As shown, in a lithium iron phosphate battery, Example 15 achieved 2000 long cycles at a 10 C rate while maintaining over 80% capacity. In contrast, Comparative Example 3 exhibited rapid capacity decay within 100 cycles. This result fully demonstrates the superior performance of polymer electrolytes with positively charged groups at high current densities.

[0052] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for producing a polymer solid-state electrolyte with a positive charge group, characterized by, Includes the following steps: S1. The polymer monomer, initiator, polymerizable ionic liquid, and lithium salt are mixed and stirred until homogeneous to obtain a solution; the cation in the selected polymerizable ionic liquid is one or more of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide, methacryloyloxyethyltrimethylammonium, [2-(vinyloxy)ethyl]trimethylammonium, and diallyl dimethylammonium; in the solution, the lithium salt concentration ranges from 0.1 to 10 M, and the mass percentage of the polymerizable ionic liquid is from 0.01% to 0.65%; S2. The above solution is poured onto the foil and solidified to form a solid electrolyte, or it is directly assembled into the battery in situ using the solution state, and finally solidified by high temperature heating to form a solid electrolyte.

2. The method for producing a polymer solid-state electrolyte with a positive charge group according to claim 1, characterized by, In S1, the selected polymer monomer is vinylene carbonate, and the selected lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorophosphate, and lithium hexafluoroarsenate.

3. The method for preparing the polymer solid electrolyte with positively charged groups as described in claim 1, characterized in that, In S1, the selected initiator is one or more of the following: dimethyl azobisisobutyrate, 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), benzoyl peroxide, lithium phenyl-2,4,6-trimethylbenzoylphosphonate, lauroyl peroxide, and azobisisobutyronitrile.

4. The method of claim 1, wherein the polymer solid-state electrolyte having a positive charge group is prepared by the steps of: (a) preparing a solution by dissolving a polymer having a positive charge group in a solvent; (b) adding a salt to the solution; (c) removing the solvent from the solution; and (d) drying the solution. The solution contains lithium salts in the range of 1–5 M and polymerizable ionic liquids in the range of 0.01%–0.35% by mass.

5. The method for preparing a polymer solid electrolyte with positively charged groups as described in claim 1, characterized in that, In S2, the foil is cast and cured, and the curing temperature range is 25-110℃.

6. The method for preparing the polymer solid electrolyte with positively charged groups as described in claim 1, characterized in that, In S2, the amount of solution used for in-situ assembly in the battery is 0.5–4 g / Ah. The specific operation of in-situ polymerization is as follows: under vacuum conditions of ≤2000 Pa, the polymerization reaction is carried out by heating at 60–120 °C for 8–48 h.

7. The method for preparing a polymer solid electrolyte with positively charged groups as described in claim 6, characterized in that, In S2, the positive electrode active material is assembled in situ into the battery and is one of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, or lithium nickel cobalt aluminum oxide.

8. The method for preparing a polymer solid electrolyte with positively charged groups as described in claim 4, characterized in that, In the solution, the lithium salt concentration ranges from 1 to 4 M, and the mass percentage of the polymerizable ionic liquid is from 0.01% to 0.15%.

9. The solid electrolyte obtained by the method for preparing the polymer solid electrolyte with positively charged groups as described in any one of claims 1 to 8.

10. The application of the method for preparing the polymer solid electrolyte with positively charged groups as described in any one of claims 1 to 8 in lithium-ion batteries.

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