Preparation method of semi-solid battery and screening method of polymerization temperature
By first injecting polymer monomers and initiators into a solid electrolyte layer during the preparation of lithium-ion batteries, then injecting lithium salts and melting them into it, the problems of flammability and polymer uniformity of liquid electrolytes are solved, and higher battery safety and cycling performance are achieved.
Patent Information
- Application Number
- CN202510798208.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-04-08
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-05
AI Technical Summary
In the prior art, the flammability of liquid electrolytes in lithium-ion batteries leads to safety problems, and the position, thickness and uniformity of the polymer inside the battery have a significant impact on impedance. How to form a high-quality semi-solid polymer layer in situ inside the battery to improve the structural stability and cycling performance of the material remains to be studied.
During the battery preparation process, polymer monomer and initiator are first injected into a solid electrolyte layer, then lithium salt is injected and melted into. The polymerization process does not affect the electrolyte, and the melting process does not affect polymerization. After the polymerization is completed, lithium salt is injected, the polymerization temperature is 60~80℃, and the reaction time is 3~10h.
The polymerization state is more uniform and the polymerization completion degree is higher, which avoids the influence of polymerization temperature on lithium salts, broadens the selection range of monomers, and improves the safety and circulation performance of the battery.
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Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese patent application number 2025104293673 filed with the China Patent Office on April 8, 2025, entitled “Method for preparing semi-solid state batteries and method for screening polymerization temperature”, the entire contents of which are incorporated by reference into this application. Technical Field
[0002] The present invention relates to the technical field of battery preparation, and in particular to a method for preparing a semi-solid battery and a method for screening a polymerization temperature. Background Art
[0003] Lithium-ion batteries, as commercially available secondary batteries, offer advantages such as high operating voltage, long cycle life, and high specific energy density. With the continuous advancement of advanced technologies and the increasing demand for high-energy-density energy storage systems, the development of high-energy-density lithium-ion batteries has become a research hotspot. The use of solid-state electrolytes can reduce the amount of electrolyte injected, making them an effective means of increasing energy density.
[0004] On the other hand, current liquid electrolytes in lithium-ion batteries are mostly organic carbonates, primarily composed of ethyl methyl carbonate, dimethyl carbonate, and ethylene carbonate. However, carbonate electrolyte systems are flammable, potentially leading to safety issues during battery charging and discharging. Solid polymers offer advantages such as high ionic conductivity, excellent mechanical properties (effectively preventing lithium dendrite growth), and excellent flame retardancy, making them an effective strategy for improving battery safety. Polymers are typically introduced into batteries through three methods: as additives in the slurry, in the electrolyte, or as coatings on the electrode or separator surfaces. In-situ polymerization after addition to the electrolyte by heating is a simple and easy method that theoretically can significantly improve safety. However, the location, thickness, and uniformity of polymer curing can significantly affect impedance. Therefore, research is underway to develop a high-quality semi-solid polymer layer in situ within the battery to enhance structural stability and cycle performance.
[0005] In view of this, the present invention is proposed. Summary of the Invention
[0006] The purpose of the present invention is to provide a method for preparing a semi-solid-state battery and a method for screening a polymerization temperature.
[0007] The present invention is achieved in that: In a first aspect, the present invention provides a method for preparing a semi-solid-state battery, comprising: Performing a first injection on the battery cell to be injected, injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the battery cell after the primary injection to allow the first solution to infiltrate the surface of the electrode, and subjecting it to a polymerization reaction temperature to polymerize the polymer monomers in the battery cell to form a solid electrolyte layer on the surface of the electrode; Opening the air bag to inject a second solution into the battery cell, and then evacuating the air bag and sealing it again; the second solution includes lithium salt; to form; Vacuum seal the battery cell.
[0008] The polymer monomer is selected from at least one of acrylate monomers, carbonate monomers and acrylamide monomers.
[0009] In an optional embodiment, at least one of the following features (1) to (3) is also included: (1) The acrylic acid ester monomer is at least one selected from methyl methacrylate, methyl acrylate, ethylene glycol dimethacrylate and ethylene glycol methacrylate; (2) The carbonate monomer is selected from at least one of vinyl ethylene carbonate and divinyl ethylene carbonate; (3) The acrylamide monomer is selected from at least one of N,N-dimethylacrylamide and N-tert-butylacrylamide.
[0010] In an optional embodiment, the polymerization reaction temperature is 60-80° C., and the reaction time is 3-10 hours.
[0011] In an optional embodiment, at least one of the following features (1) to (6) is also included: (1) The formation temperature is 40~50℃; (2) The concentration of the polymer monomer in the first solution is 2-10% wt; (3) The first solution accounts for 80-90% by volume of the total injection volume, and the second solution accounts for 10-20% by volume of the total injection volume; (4) The battery cell is a soft-pack battery cell, which is placed horizontally after being filled and sealed once, and the battery cell is also pressurized horizontally; (5) The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bis(oxalatoborate); (6) The concentration of the lithium salt in the second solution is 0.8-1.4 mol / L.
[0012] In an optional embodiment, the solvent in the first solution is selected from at least one of cyclic esters and linear esters.
[0013] In an optional embodiment, the solvent in the second solution is selected from at least one of cyclic esters and linear esters.
[0014] In an optional embodiment, at least one of features (1) and (2) is also included: (1) The cyclic ester includes at least one of ethylene carbonate, propylene carbonate and vinylene carbonate; (2) The linear esters include at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate and vinylene carbonate.
[0015] In a second aspect, the present invention provides a method for screening a suitable polymerization temperature for in-situ curing, comprising: Step (A): Filling the battery cell to be filled with liquid by injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the injected cell to allow the first solution to soak the electrode surface, and subjecting the cell to a predetermined polymerization temperature to polymerize the polymer monomers in the cell to form a solid electrolyte layer on the electrode surface; Disassemble the battery cell after injection to obtain the electrode to be evaluated; Step (B) Repeating the step (A) at different polymerization temperatures to be determined to obtain multiple electrodes to be evaluated; By testing the ionic conductivity, interface / charge transfer impedance of the electrode and observing the distribution and density of the solid electrolyte layer on the surface of the electrode under an electron microscope, the electrode with uniform density, low conductivity and low impedance corresponds to the optimal polymerization temperature.
[0016] The present invention has the following beneficial effects: The preparation method provided by the present invention injects polymer monomers and initiators into the battery cell before the lithium salt, and performs a polymerization reaction before the lithium salt is injected, so that the polymerization process does not affect the electrolyte; after the polymerization is completed, the electrolyte containing the lithium salt is injected and then formed, and the formation process does not affect the polymerization reaction, so that the polymerization state of the polymer is more uniform and the polymerization completion degree is higher; because the lithium salt is injected after the polymerization is completed, there is no need to consider the influence of the polymerization temperature on the lithium salt, so the range of monomer selection is wider than that of the prior art. DETAILED DESCRIPTION
[0017] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.
[0018] The features and performance of the present invention are further described in detail below with reference to the embodiments.
[0019] The method for preparing a semi-solid-state battery provided by an embodiment of the present invention includes: Performing a first injection on the battery cell to be injected, injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the battery cell after the primary injection to allow the first solution to infiltrate the surface of the electrode, and subjecting it to a polymerization reaction temperature to polymerize the polymer monomers in the battery cell to form a solid electrolyte layer on the surface of the electrode; Opening the air bag to inject a second solution into the battery cell, and then evacuating the air bag and sealing it again; the second solution includes lithium salt; to form; Vacuum seal the battery cell.
[0020] The preparation method provided by the present invention injects polymer monomers and initiators into the battery cell before the lithium salt, and performs a polymerization reaction before the lithium salt is injected, so that the polymerization process does not affect the electrolyte; after the polymerization is completed, the electrolyte containing the lithium salt is injected and then formed, and the formation process does not affect the polymerization reaction, so that the polymerization state of the polymer is more uniform and the polymerization completion degree is higher; because the lithium salt is injected after the polymerization is completed, there is no need to consider the influence of the polymerization temperature on the lithium salt, so the range of monomer selection is wider than that of the prior art.
[0021] Optionally, the polymer monomer is selected from at least one of acrylate monomers, carbonate monomers and acrylamide monomers. The solid electrolytes generated after polymerization of these monomers all have good electrical conductivity.
[0022] Specifically, the acrylate monomer is selected from at least one of methyl methacrylate, methyl acrylate, ethylene glycol dimethacrylate and ethylene glycol methacrylate; the carbonate monomer is selected from at least one of vinyl ethylene carbonate and divinyl ethylene carbonate; and the acrylamide monomer is selected from at least one of N,N-dimethylacrylamide and N-tert-butylacrylamide.
[0023] Optionally, the solvent in the first solution is selected from at least one of cyclic esters and linear esters.
[0024] Optionally, the cyclic esters include at least one of ethylene carbonate, propylene carbonate and vinylene carbonate.
[0025] Optionally, the linear esters include at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate and vinylene carbonate.
[0026] Optionally, the concentration of the polymer monomer in the first solution is 2-10% wt.
[0027] Optionally, the concentration of the initiator in the first solution is 1-2% wt.
[0028] Optionally, the first solution accounts for 80-90%vt of the total injection volume.
[0029] Optionally, the polymerization reaction temperature is 60-80° C., and the reaction time is 3-10 h.
[0030] Optionally, the solvent in the second solution is also selected from at least one of cyclic esters and linear esters.
[0031] Optionally, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bis(oxalatoborate); Optionally, the concentration of the lithium salt in the second solution is 0.8-1.4 mol / L.
[0032] Optionally, the second solution accounts for 10-20% by volume of the total injection volume.
[0033] Optionally, the battery cell is a soft-pack battery cell, which is placed horizontally after being filled with liquid and sealed once, and the battery cell is also pressurized horizontally.
[0034] The soft-pack battery cells are pressurized and placed flat, instead of the vertical placement method used in most forming machines, which can avoid the influence of gravity on the distribution of polymers.
[0035] Optionally, the formation temperature is 40-50° C. Optionally, the formation process is pressurized to press out gas generated after the formation.
[0036] The present invention provides a method for screening a suitable polymerization temperature for in-situ curing, comprising: Step (A): Filling the battery cell to be filled with liquid by injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the injected cell to allow the first solution to soak the electrode surface, and subjecting the cell to a predetermined polymerization temperature to polymerize the polymer monomers in the cell to form a solid electrolyte layer on the electrode surface; Disassemble the battery cell after injection to obtain the electrode to be evaluated; Step (B) Repeating the step (A) at different polymerization temperatures to be determined to obtain multiple electrodes to be evaluated; The ionic conductivity, interface / charge transfer impedance of the electrode are tested by single-cell / button cell methods, and the distribution and density of the solid electrolyte layer on the surface of the electrode are observed by electron microscopy. The electrode with uniform density, low conductivity and low impedance corresponds to the optimal polymerization temperature.
[0037] The screening method provided by the present invention is simple to operate and can screen the polymerization temperature of polymers in a semi-solid battery, thereby obtaining the optimal polymerization temperature, thereby facilitating the preparation of a semi-solid battery with good performance.
[0038] Example 1 Lithium iron phosphate, conductive agent (conductive carbon black), and adhesive (PVDF) are mixed in a mass ratio of 97:1:2 to prepare a slurry, which is then coated on aluminum foil to prepare a positive electrode sheet. Graphite, conductive agent (conductive carbon black), and adhesive (CMC) were mixed in a mass ratio of 97.5:1:1.5 to prepare a slurry, which was then coated on aluminum foil to prepare a negative electrode sheet.
[0039] The positive electrode sheet, the negative electrode sheet and the separator are made into a soft-pack battery cell ready for liquid injection.
[0040] The cell to be injected is injected with a first solution, and then the cell is sealed with a vacuum air bag. The first solution contains a polymer monomer (polyethylene glycol diacrylate) at a concentration of 8% by weight, an initiator (azobisisobutyronitrile) at a concentration of 1% by weight, a solvent of EC:DMC:EMC = 1:1:1 (volume ratio), and additives of VC 2 wt% and FEC 1 wt%. The injection volume is 80% by volume of the total injection volume. Lay the cell flat after the primary injection, apply pressure to the cell so that the first solution soaks the electrode surface, and place it at 45° C. for 4 hours to polymerize the polymer monomers in the cell and form a solid electrolyte layer on the electrode surface; The air bag was opened and the battery cell was injected with the second solution. After injection, the air bag was evacuated and sealed again. The solvent in the second solution was EC:DMC:EMC = 1:1:1 (volume ratio), the LiPF6 concentration was 1 M (molar concentration), and the additives were VC 2 wt%, FEC 1 wt%; Pressurized at 45℃; Vacuum seal the battery cell.
[0041] Example 2 Lithium iron phosphate, conductive agent (conductive carbon black), and adhesive (PVDF) are mixed in a mass ratio of 97:1:2 to prepare a slurry, which is then coated on aluminum foil to prepare a positive electrode sheet. Graphite, conductive agent (conductive carbon black), and adhesive (CMC) were mixed in a mass ratio of 97.5:1:1.5 to prepare a slurry, which was then coated on aluminum foil to prepare a negative electrode sheet.
[0042] The positive electrode sheet, the negative electrode sheet and the separator are made into a soft-pack battery cell ready for liquid injection.
[0043] The battery cell to be injected is injected with a first solution, and then the battery cell is sealed with a vacuum air bag. The first solution contains ethylene glycol methacrylate at a concentration of 8% by weight, an initiator azobisisobutyronitrile at a concentration of 1% by weight, a solvent of EC:DMC:EMC = 1:1:1 (volume ratio), and additives of VC 2 wt% and FEC 1 wt%. The injection volume is 80% by volume of the total injection volume. Lay the cell flat after the primary injection, pressurize the cell so that the first solution soaks the electrode surface, and place it at 70° C. for 4 hours to polymerize the polymer monomers in the cell and form a solid electrolyte layer on the electrode surface; The air bag was opened and the battery cell was injected with the second solution. After the injection, the air bag was evacuated and sealed again. The solvent in the second solution was EC:DMC:EMC = 1:1:1 (volume ratio), LiPF6 concentration was 1.4M (molar concentration), VC was 2 wt%, and FEC was 1 wt%. Pressurized at 45℃; Vacuum seal the battery cell.
[0044] Example 3 Lithium iron phosphate, conductive agent (conductive carbon black), and adhesive (PVDF) are mixed in a mass ratio of 97:1:2 to prepare a slurry, which is then coated on aluminum foil to prepare a positive electrode sheet. Graphite, conductive agent (conductive carbon black), and adhesive (CMC) were mixed in a mass ratio of 97.5:1:1.5 to prepare a slurry, which was then coated on aluminum foil to prepare a negative electrode sheet.
[0045] The positive electrode sheet, the negative electrode sheet and the separator are made into a soft-pack battery cell ready for liquid injection.
[0046] The battery cell to be injected is injected with a first solution, and then the battery cell is sealed with a vacuum air bag. The first solution contains 8% wt of ethylene carbonate, 1% wt of azobisisobutyronitrile as an initiator, a solvent of EC:DMC:EMC = 1:1:1 (volume ratio), and additives of 2 wt% VC and 1 wt% FEC. The injection volume is 80% of the total injection volume. Lay the cell flat after the primary injection, pressurize the cell so that the first solution soaks the electrode surface, and place it at 70° C. for 4 hours to polymerize the polymer monomers in the cell and form a solid electrolyte layer on the electrode surface; The air bag was opened and the battery cell was injected with the second solution. After the injection, the air bag was evacuated and sealed again. The solvent in the second solution was EC:DMC:EMC = 1:1:1 (volume ratio), LiPF6 concentration was 0.8 M (molar concentration), VC 2 wt%, FEC 1 wt%; Pressurized at 45℃; Vacuum seal the battery cell.
[0047] Comparative Example 1 This comparative example is basically the same as Example 1, except that the existing injection method is used for injection: dissolving the polymer monomer, initiator and lithium salt in a solvent to obtain a mixed electrolyte; Inject the mixed electrolyte into the battery cell to be filled, and then vacuum seal it after injection; Place the battery cell at 45°C for formation; Then the temperature was raised to 45 °C for polymerization for 4 h; Finally, vacuum seal the battery cell.
[0048] Comparative Example 2 This comparative example is basically the same as Example 2, except that the existing injection method is used for injection: dissolving the polymer monomer, initiator and lithium salt in a solvent to obtain a mixed electrolyte; Inject the mixed electrolyte into the battery cell to be filled, and then vacuum seal it after injection; Place the battery cell at 45°C for formation; Then the temperature was raised to 70°C for polymerization for 4 h; Finally, vacuum seal the battery cell.
[0049] Comparative Example 3 This comparative example is basically the same as Example 3, except that the existing injection method is used for injection: dissolving the polymer monomer, initiator and lithium salt in a solvent to obtain a mixed electrolyte; Inject the mixed electrolyte into the battery cell to be filled, and then vacuum seal it after injection; Place the battery cell at 45°C for formation; Then the temperature was raised to 45 °C for polymerization for 4 h; Finally, vacuum seal the battery cell.
[0050] Experimental example The electrochemical performance of the battery cells prepared in each embodiment and comparative example was measured. Specifically, the testing method involved taking the electrode pieces to make symmetrical cells and testing the ion diffusion impedance at 25°C, a potential amplitude of 5mV, and a frequency of 0.05-10000Hz. The charge transfer impedance of the prepared single-cell cells was also tested at 25°C. Surface and cross-sectional electron microscopy were also performed on the electrode pieces to observe the polymer morphology and density.
[0051] Record the test results in Table 1.
[0052] Table 1 Electrochemical properties of the cells prepared in the examples and comparative examples
[0053] From the experimental results in Table 1, it can be seen that the battery cells prepared in various embodiments of the present invention all have better electrochemical performance.
[0054] Comparing Example 1 with Comparative Example 1, both use monomers that can be fully polymerized at higher temperatures. Their ion diffusion impedance has no obvious advantage, and their charge transfer impedance is slightly lower than that of Comparative Example 1. This shows that the order of formation and polymerization has little effect on the performance of the battery cell. Comparing Example 2 with Comparative Example 2, the charge transfer impedance of Comparative Example 2 is significantly worse than that of Example 2. This result may be due to the fact that the polymerization of Comparative Example 2 was carried out at a high polymerization temperature after formation, which caused the decomposition and failure of the lithium salt during the polymerization process, thereby deteriorating the subsequent SEI film formation of the battery cell. Comparing Example 3 with Comparative Example 3, the ion diffusion impedance and charge transfer impedance of Comparative Example 3 are significantly worse than those of Example 3. This result may be because after the formation of Comparative Example 3, a relatively high temperature polymerization is adopted in an environment to avoid high-temperature deterioration of the lithium salt, resulting in insufficient polymerization and low polymerization completion, thereby making the ion diffusion impedance and charge transfer impedance of the battery cell worse. In summary, the preparation method of the present invention has the following advantages: 1. The polymerization step is set before the formation. Since the polymerization process will not affect the electrolyte, and the formation process will not affect the polymerization process of the polymer, the polymerization state of the polymer is more uniform and the polymerization completion degree is higher.
[0055] 2. Since the improved battery cells can be placed horizontally for pressurization, instead of the vertical placement method used in most forming machines, the influence of gravity on the distribution of polymers can be avoided.
[0056] 3. The polymerization step is advanced, and the state of the polymer can be evaluated separately after polymerization, which can be used as a method for rapid screening of the appropriate polymerization temperature for in situ curing.
[0057] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.
Claims
1. A method for preparing a semi-solid-state battery, characterized in that: include: Performing a first injection on the battery cell to be injected, injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the battery cell after the primary injection to allow the first solution to infiltrate the surface of the electrode while removing gases that may be generated by the polymerization reaction, and subjecting it to the polymerization reaction temperature to polymerize the polymer monomers in the battery cell to form a solid electrolyte layer on the surface of the electrode; Open the air bag and inject the second solution into the battery cell for the second time. After the injection, evacuate the air bag and seal it again. The second solution includes a lithium salt; to form; Vacuum seal the battery cell.
2. The preparation method according to claim 1, characterized in that The polymer monomer is selected from at least one of acrylate monomers, carbonate monomers and acrylamide monomers.
3. The preparation method according to claim 2, characterized in that Also includes at least one of the following features (1) to (3): (1) The acrylic acid ester monomer is at least one selected from methyl methacrylate, methyl acrylate, ethylene glycol dimethacrylate and ethylene glycol methacrylate; (2) The carbonate monomer is selected from at least one of vinyl ethylene carbonate and divinyl ethylene carbonate; (3) The acrylamide monomer is selected from at least one of N,N-dimethylacrylamide and N-tert-butylacrylamide.
4. The preparation method according to claim 2, characterized in that The polymerization reaction temperature is 60~80℃, and the reaction time is 3~10h.
5. The preparation method according to claim 1, characterized in that Also includes at least one of the following features (1) to (6): (1) The formation temperature is 40~50℃; (2) The concentration of the polymer monomer in the first solution is 2-10% wt; (3) The first solution accounts for 80-90% by volume of the total injection volume, and the second solution accounts for 10-20% by volume of the total injection volume; (4) The battery cell is a soft-pack battery cell, which is placed horizontally after being filled and sealed once, and the battery cell is also pressurized horizontally; (5) The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bis(oxalatoborate); (6) The concentration of the lithium salt in the second solution is 0.8-1.4 mol / L.
6. The preparation method according to claim 1, characterized in that The solvent in the first solution is selected from at least one of cyclic esters and linear esters.
7. The preparation method according to claim 6, characterized in that Also includes at least one of features (1) and (2): (1) The cyclic ester includes at least one of ethylene carbonate, propylene carbonate and vinylene carbonate; (2) The linear esters include at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate and vinylene carbonate.
8. The preparation method according to claim 1, characterized in that The solvent in the second solution is selected from at least one of cyclic esters and linear esters.
9. The preparation method according to claim 8, characterized in that Also includes at least one of features (1) and (2): (1) The cyclic ester includes at least one of ethylene carbonate, propylene carbonate and vinylene carbonate; (2) The linear esters include at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate and vinylene carbonate.
10. A method for screening a suitable polymerization temperature for in-situ curing, characterized in that: include: Step (A): Filling the battery cell to be filled with liquid by injecting a first solution, and then sealing the cell by evacuating a vacuum air bag; the first solution includes a polymer monomer and an initiator, but does not include a lithium salt; Pressurizing the injected cell to allow the first solution to soak the electrode surface, and subjecting the cell to a predetermined polymerization temperature to polymerize the polymer monomers in the cell to form a solid electrolyte layer on the electrode surface; Disassemble the battery cell after injection to obtain the electrode to be evaluated; Step (B) Repeating the step (A) at different polymerization temperatures to be determined to obtain multiple electrodes to be evaluated; By testing the ionic conductivity, interface / charge transfer impedance of the electrode and observing the distribution and density of the solid electrolyte layer on the surface of the electrode under an electron microscope, the electrode with uniform density, low conductivity and low impedance corresponds to the optimal polymerization temperature.