Composite electrolyte precursor and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium batteries, and discloses a composite electrolyte precursor and a preparation method and application thereof.The composite electrolyte precursor comprises a three-dimensional skeleton and a pre-polymerization solution loaded on the three-dimensional skeleton, the pre-polymerization solution is obtained by mixing solvated ionic liquid, a polymer matrix and an initiator, the three-dimensional skeleton is an alumina fiber membrane, and the polymer matrix is polyethylene glycol diacrylate or vinylene carbonate; the preparation method of the composite electrolyte precursor comprises the following steps: (1) mixing a solvated ionic liquid, a polymer matrix and an initiator to obtain a pre-polymerized liquid; and (2) infiltrating the three-dimensional skeleton in the prepolymerization liquid to obtain the composite electrolyte precursor. The composite electrolyte precursor disclosed by the invention takes the solvated ionic liquid as a lithium ion conductor, so that the interface impedance of the composite electrolyte precursor can be effectively reduced, the ionic conductivity of the composite electrolyte precursor is improved, and the electrochemical performance of a battery is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to a composite electrolyte precursor, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of new energy technologies, there is an increasing market demand for energy storage devices with high energy density. Lithium-ion batteries have attracted extensive attention in the new energy field due to their high energy density and long cycle life. However, traditional lithium-ion batteries all use liquid electrolytes, which have safety problems such as leakage or fire. To improve the safety performance of the battery, using solid electrolytes to replace traditional electrolytes is an effective method.

[0003] Solid electrolytes can be mainly divided into inorganic solid electrolytes and polymer solid electrolytes. Compared with polymer solid electrolytes, inorganic solid electrolytes often have a higher ionic conductivity at room temperature, generally ranging from 10 -2 -10 -4 S / cm. For example, sulfide-based Li 10 GeP 2 S 12 and oxide garnet-type Li 7 La 3 Zr 2 O 12 . Among them, the sulfide solid electrolyte has a high ionic conductivity comparable to that of liquid electrolytes at room temperature, and can reach a maximum of 10 -2 S / cm. However, the preparation process of inorganic solid electrolytes is relatively cumbersome, and the contact with electrodes is poor, with a large interfacial impedance, which seriously hinders the application of inorganic solid electrolytes in lithium batteries. Compared with inorganic solid electrolytes, polymer solid electrolytes have better interfacial compatibility and good flexibility. In recent years, polymer solid electrolytes with organic matrices such as polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF) have received extensive attention and research. This is due to the fact that the polar groups of polymers can complex with alkali metal salts. However, polymers have a certain degree of crystallinity, which limits the segmental motion at room temperature. Even adding fillers can reduce the crystallinity and promote ion conduction, but the ionic conductivity is still at a relatively low level. Therefore, there is an urgent need to provide an electrolyte with a simple preparation process, high ionic conductivity, and low interfacial impedance. Summary of the Invention

[0004] In view of this, the present invention provides a composite electrolyte precursor, a preparation method thereof, and an application thereof to solve the problems of the complex preparation process of existing inorganic solid electrolytes, large interfacial impedance, and low ionic conductivity of polymer solid electrolytes.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: On the one hand, the present invention provides a composite electrolyte precursor, comprising a three-dimensional skeleton and a prepolymer solution loaded on the three-dimensional skeleton, wherein the prepolymer solution is obtained by mixing a solvated ionic liquid, a polymer matrix, and an initiator; The three-dimensional skeleton is an alumina fiber membrane, and the polymer matrix is polyethylene glycol diacrylate or vinylene carbonate.

[0006] Preferably, the mass ratio of the solvated ionic liquid, the polymer matrix, and the initiator is 2:(0.1747 - 0.8):(0.0124 - 0.0168).

[0007] Preferably, the thickness of the three-dimensional skeleton is 100 - 200 μm, and the loading amount of the prepolymer solution on the three-dimensional skeleton is ≥0.174 mL / cm 2 .

[0008] Preferably, the initiator includes one or more of azobisisobutyronitrile and benzoyl peroxide.

[0009] Preferably, the raw materials of the prepolymer solution further include an additive, and the mass ratio of the solvated ionic liquid to the additive is 2:(0.3331 - 0.4225).

[0010] Preferably, the additive includes one or more of fluoroethylene carbonate and hydrofluoroether.

[0011] On the other hand, the present invention further provides a preparation method of the composite electrolyte precursor according to any one of the above, comprising the following steps: (1) Mix the solvated ionic liquid, the polymer matrix, and the initiator to obtain a prepolymer solution; (2) Immerse the three-dimensional skeleton in the prepolymer solution to obtain a composite electrolyte precursor.

[0012] Preferably, the mixing is carried out by stirring at room temperature for 12 - 24 h.

[0013] On yet another aspect, the present invention further provides an application of the composite electrolyte precursor according to any one of the above or the composite electrolyte precursor prepared by the method according to any one of the above in a battery.

[0014] Preferably, the application includes assembling the composite electrolyte precursor into a battery and performing an in-situ thermal polymerization reaction to obtain a battery.

[0015] Preferably, the temperature of the in-situ thermal polymerization reaction is 70 - 100 °C, and the time is 1 - 3 h.

[0016] The present invention provides a composite electrolyte precursor, a preparation method and an application thereof. Compared with the prior art, the beneficial effects are as follows: The composite electrolyte generated by in-situ polymerization of the composite electrolyte precursor provided by the present invention in a battery has excellent electrochemical performance. It uses an alumina fiber membrane with flame retardancy and can promote the dissociation of lithium salts as the three-dimensional framework for in-situ polymerization, uses a solvated ionic liquid as the active part for lithium ion conduction, and adds a polymer matrix and an initiator to obtain through in-situ polymerization. The preparation method is simple and efficient; moreover, the composite electrolyte precursor of the present invention uses a solvated ionic liquid as a lithium ion conductor, which can ensure that the composite electrolyte has high ionic conductivity and electrochemical stability; in addition, through the in-situ thermal polymerization process, the prepolymer solution can fully wet the electrode and maintain good contact after curing, thereby effectively reducing the interfacial impedance. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0018] Figure 1 Scanning electron microscope image of the composite electrolyte of Example 1 of the present invention; Figure 2 Scanning electron microscope image of the composite electrolyte of Comparative Example 1 of the present invention; Figure 3 Schematic diagram of the bulk impedance and ionic conductivity of the composite electrolyte of Example 1 of the present invention at room temperature; Figure 4 Schematic diagram of the bulk impedance and ionic conductivity of the composite electrolyte of Comparative Example 1 of the present invention at room temperature; Figure 5 Polarization current curve graph of the composite electrolyte of Example 1 of the present invention; Figure 6 Polarization current curve graph of the composite electrolyte of Comparative Example 1 of the present invention; Figure 7 Activation energy curve graph of the composite electrolyte of Example 1 of the present invention; Figure 8 Activation energy curve graph of the composite electrolyte of Comparative Example 1 of the present invention; Figure 9 Schematic diagram of the rate performance of the solid-state battery using the composite electrolyte precursor of Example 1 of the present invention at room temperature; Figure 10 Schematic diagram of the rate performance of the solid-state battery using the composite electrolyte precursor of Comparative Example 1 of the present invention at room temperature. Detailed implementation manners

[0019] The present invention will be described below through specific embodiments. Those skilled in the art can understand that the following specific embodiments are only for the purpose of illustration and do not limit the scope of the present invention in any way. Additionally, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If the specific processing conditions and methods are not clearly described in the following embodiments, the conditions and methods known in the art can be used for processing.

[0020] In one aspect of the present invention, a composite electrolyte precursor is proposed, which includes a three-dimensional skeleton and a prepolymer solution loaded on the three-dimensional skeleton. The prepolymer solution is obtained by mixing a solvated ionic liquid, a polymer matrix, and an initiator. The three-dimensional skeleton is an alumina fiber membrane, and the polymer matrix is polyethylene glycol diacrylate or vinylene carbonate.

[0021] In some embodiments of the present invention, the molecular weight of polyethylene glycol diacrylate is 600 - 1000, and it can be, for example, 600, 700, 800, 900, 1000, etc., without special limitation in this regard.

[0022] In some embodiments of the present invention, the initiator is azobisisobutyronitrile.

[0023] In some embodiments of the present invention, the mass ratio of the solvated ionic liquid, the polymer matrix, and the initiator is 2:(0.1747 - 0.8):(0.0124 - 0.0168), and it can be, for example, 2:0.1747:0.0124, 2:0.5:0.015, 2:0.1747:0.0168, 2:0.8:0.0124, 2:0.35:0.0156, etc. The change in the ratio among the solvated ionic liquid, the polymer matrix, and the initiator will cause a change in the ionic conductivity of the composite electrolyte precursor. Within the above range defined in the present invention, the composite electrolyte precursor can have high ionic conductivity.

[0024] In some embodiments of the present invention, the solvated ionic liquid is prepared from tetraethylene glycol dimethyl ether / triethylene glycol dimethyl ether and lithium bis(trifluoromethanesulfonyl)imide, and the molar ratio of tetraethylene glycol dimethyl ether / triethylene glycol dimethyl ether to lithium bis(trifluoromethanesulfonyl)imide is 1:1. It should be noted that this is only one of the methods for preparing the solvated ionic liquid, and other methods disclosed in the prior art can also be used to prepare the solvated ionic liquid.

[0025] Specifically, in a specific embodiment of the present invention, the solvated ionic liquid is prepared by the following method: under a protective atmosphere, tetraethylene glycol dimethyl ether and lithium bis(trifluoromethanesulfonyl)imide with a molar ratio of 1:1 are stirred at a temperature of 60 - 80 °C for 24 - 48 h until fully mixed to obtain the solvated ionic liquid.

[0026] In some embodiments of the present invention, the thickness of the three-dimensional framework is 100 - 200 μm, for example, it can be 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, etc. The loading amount of the prepolymer solution on the three-dimensional framework ≥ 0.174 mL / cm 2 , if the loading amount of the prepolymer solution is too small, it will cause the battery finally prepared to malfunction.

[0027] In some embodiments of the present invention, the raw materials of the prepolymer solution of the composite electrolyte precursor further include an additive, and the additive is vinylene carbonate fluoride. The mass ratio of the solvated ionic liquid to the additive is 2:(0.3331 - 0.4225), for example, it can be 2:0.3331, 2:0.4, 2:0.4225, etc. Changes in the ratio among the solvated ionic liquid, the polymer matrix, the initiator, and the additive will cause changes in the ionic conductivity of the composite electrolyte precursor. Within the above range defined in the present invention, the composite electrolyte precursor can have high ionic conductivity.

[0028] On the other hand, the present invention provides a method for preparing the composite electrolyte precursor according to any one of the above, comprising the following steps: (1) Mix the solvated ionic liquid, the polymer matrix, and the initiator to obtain a prepolymer solution; (2) Immerse the three-dimensional framework in the prepolymer solution to obtain the composite electrolyte precursor.

[0029] In the present invention, first, the solvated ionic liquid, the polymer matrix, and the initiator are mixed to obtain a prepolymer solution.

[0030] In some embodiments of the present invention, the mixing process of the solvated ionic liquid, the polymer matrix, and the initiator is carried out under a protective atmosphere, and the protective atmosphere can be argon, nitrogen, etc. Specifically, the prepolymer solution can be prepared in an argon glove box; the mixing is carried out by stirring at room temperature for 12 - 24 h, for example, it can be 12 h, 16 h, 20 h, 24 h, etc.

[0031] In some embodiments of the present invention, when the raw materials of the prepolymer solution further include an additive, the solvated ionic liquid, the polymer matrix, the initiator, and the additive are mixed to obtain a prepolymer solution. The specific mixing process is the same as that without the additive and will not be elaborated here.

[0032] In the present invention, after obtaining the prepolymer solution, the three-dimensional skeleton is infiltrated in the prepolymer solution to obtain a composite electrolyte precursor.

[0033] In some embodiments of the present invention, the infiltration can be achieved by immersing the three-dimensional skeleton in the prepolymer solution or by dropping a sufficient amount of the prepolymer solution onto the three-dimensional skeleton, and there is no special limitation on how to achieve infiltration.

[0034] In some embodiments of the present invention, the three-dimensional skeleton is an alumina fiber membrane. The alumina fiber membrane is prepared by electrospinning technology, and the specific steps are as follows: Aluminum isopropoxide is catalytically hydrolyzed in an ethanol solution using concentrated hydrochloric acid and acetic acid, polyvinylpyrrolidone is added as a spinning aid, and after uniform stirring, electrospinning is carried out to obtain an AlOOH intermediate fiber membrane, which is then calcined at a high temperature to obtain an alumina fiber membrane. The mass ratio of concentrated hydrochloric acid, acetic acid, ethanol, aluminum isopropoxide, and polyvinylpyrrolidone can be 1:1:8:2:0.3; the spinning voltage is 20 - 30 kV, for example, it can be 20 kV, 25 kV, 23 kV, etc.; the temperature of high-temperature calcination is 600 - 800 °C, for example, it can be 600 °C, 700 °C, 800 °C, and the high-temperature calcination time is 4 - 6 h, for example, it can be 4 h, 5 h, 6 h, etc. It should be noted that the above is only one method for preparing the alumina fiber membrane, and other methods disclosed in the prior art can also be used to prepare the alumina fiber membrane.

[0035] In another aspect of the present invention, the present invention also provides an application of the composite electrolyte precursor described in any one of the above or the composite electrolyte precursor prepared by the method described in any one of the above in a battery.

[0036] In some embodiments of the present invention, it includes assembling the composite electrolyte precursor into a battery and performing an in-situ thermal polymerization reaction to obtain a battery. Specifically, the composite electrolyte precursor and electrode materials (for example, lithium iron phosphate can be used as the positive electrode and a lithium sheet can be used as the negative electrode) are assembled together, and then placed in a muffle furnace for an in-situ thermal polymerization reaction to obtain a battery, and a composite electrolyte is formed in-situ on the solid-state battery.

[0037] In some embodiments of the present invention, the temperature of the in-situ thermal polymerization reaction is 70 - 100 °C, for example, it can be 70 °C, 80 °C, 90 °C, 100 °C, etc.; the time of the in-situ thermal polymerization reaction is 1 - 3 h, for example, it can be 1 h, 2 h, 3 h, etc.

[0038] It can be understood that the longer the in-situ thermal polymerization time and the higher the temperature, the lower the ionic conductivity of the composite electrolyte in the solid-state battery, and vice versa, but at the same time, the mechanical strength of the composite electrolyte will also decrease. Under the in-situ thermal polymerization reaction conditions defined in the present invention, the composite electrolyte can have high ionic conductivity and good mechanical strength.

[0039] The technical solutions in the present invention will be clearly and completely described below in conjunction with specific embodiments. The embodiments of this application are only for illustration. All other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0040] Example 1

[0041] This example provides a preparation method for a composite electrolyte precursor, and the specific steps are as follows: (1) In an argon glove box, stir diglyme and lithium bis(trifluoromethanesulfonyl)imide with a molar ratio of 1:1 at a temperature of 60 °C for 24 h to obtain a solvated ionic liquid; (2) Catalyze the hydrolysis of aluminum isopropoxide with concentrated hydrochloric acid and acetic acid in an ethanol solution, add polyvinylpyrrolidone as a spinning aid, stir evenly for 12 h and then electrospin at a spinning voltage of 25 kV to obtain an AlOOH intermediate fiber membrane, and then calcine at a high temperature of 800 °C for 4 h to obtain an alumina fiber membrane; among them, the mass ratio of concentrated hydrochloric acid, acetic acid, ethanol, aluminum isopropoxide and polyvinylpyrrolidone can be 1:1:8:2:0.3; (3) Mix the solvated ionic liquid, vinylene carbonate, azobisisobutyronitrile and fluoroethylene carbonate according to a mass ratio of 2:0.8:0.0168:0.4225, and stir at 25 °C for 12 h to obtain a prepolymer solution; (4) Take the prepolymer solution and drop it on an alumina fiber membrane with a thickness of 100 μm, so that the loading amount of the prepolymer solution on the alumina fiber membrane is 0.174 mL / cm 2 , to obtain a composite electrolyte precursor.

[0042] Example 2

[0043] This example provides a preparation method for a composite electrolyte precursor, and the specific steps are as follows: (1) In an argon glove box, stir diglyme and lithium bis(trifluoromethanesulfonyl)imide with a molar ratio of 1:1 at a temperature of 60 °C for 24 h to obtain a solvated ionic liquid; (2) Catalyze the hydrolysis of aluminum isopropoxide with concentrated hydrochloric acid and acetic acid in an ethanol solution, add polyvinylpyrrolidone as a spinning aid, stir evenly for 12 h and then electrospin at a spinning voltage of 25 kV to obtain an AlOOH intermediate fiber membrane, and then calcine at a high temperature of 600 °C for 4 h to obtain an alumina fiber membrane; among them, the mass ratio of concentrated hydrochloric acid, acetic acid, ethanol, aluminum isopropoxide and polyvinylpyrrolidone can be 1:1:8:2:0.3; (3) Mix the solvated ionic liquid, polyethylene glycol diacrylate, azobisisobutyronitrile, and vinyl fluorocarbonate in a mass ratio of 2:0.8:0.0168:0.4225, and stir for 12 h at 25 °C to obtain a prepolymer solution; (4) Take the prepolymer solution and drop it onto an alumina fiber membrane with a thickness of 100 μm, such that the loading of the prepolymer solution on the alumina fiber membrane is 0.174 mL / cm 2 to obtain a composite electrolyte precursor.

[0044] Comparative Example 1 This comparative example is basically the same as Example 1, except that the solvated ionic liquid is replaced with a deep eutectic solvent, and the deep eutectic solvent, polyethylene glycol diacrylate, azobisisobutyronitrile, and vinyl fluorocarbonate are mixed in a mass ratio of 2:0.1747:0.0124:0.3331.

[0045] Among them, the preparation method of the deep eutectic solvent is as follows: In an argon glove box, stir N-methylacetamide and lithium bis(trifluoromethanesulfonyl)imide with a molar ratio of 3:1 at a temperature of 60 °C for 12 h to obtain the deep eutectic solvent.

[0046] Combine the composite electrolyte precursors of Examples 1-2 and Comparative Example 1 with lithium metal sheets and lithium iron phosphate respectively and assemble them into batteries. The battery assembly process is completed in a glove box with the oxygen and moisture content less than 0.1 ppm; Heat the assembled batteries in a muffle furnace at 100 °C for 60 min for in-situ thermal polymerization to obtain batteries with composite electrolytes.

[0047] As Figure 1 and Figure 2 shown, the scanning electron microscope images of the composite electrolytes of Example 1 and Comparative Example 1 of the present invention are respectively. It can be seen from the figure that the three-dimensional framework alumina fiber membranes are filled in the composite electrolytes of Example 1 and Comparative Example 1 and are well coupled as a whole.

[0048] As Figure 3 and Figure 4 shown, the schematic diagrams of the bulk impedance and ionic conductivity of the composite electrolytes of Example 1 and Comparative Example 1 of the present invention at room temperature are respectively. It can be seen from the figure that compared with Comparative Example 1, the bulk impedance of the composite electrolyte of Example 1 is smaller; and it can be seen from the figure that the ionic conductivity of the composite electrolyte of Comparative Example 1 is 8.93×10 -4 S / cm, and the ionic conductivity of the composite electrolyte of Example 1 is 4.32×10 -3S / cm. That is, compared with the composite electrolyte with deep eutectic solvent as the lithium-ion conductor, the composite electrolyte with solvated ionic liquid as the lithium-ion conductor has a smaller bulk impedance and a higher ionic conductivity, which is more conducive to reducing polarization and enabling the battery to have more excellent electrochemical performance.

[0049] As Figure 5 and Figure 6 shown, they are respectively the polarization current curve graphs of the composite electrolytes of Example 1 and Comparative Example 1 of the present invention. It can be seen from the figures that the lithium-ion transference number of the composite electrolyte of Example 1 is 0.465, and the lithium-ion transference number of the composite electrolyte of Comparative Example 1 is 0.405. That is, compared with the composite electrolyte with deep eutectic solvent as the lithium-ion conductor, the composite electrolyte with solvated ionic liquid as the lithium-ion conductor has a higher lithium-ion transference number and can better reduce the influence of concentration polarization.

[0050] As Figure 7 and Figure 8 shown, they are respectively the activation energy curve graphs of the composite electrolytes of Example 1 and Comparative Example 1 of the present invention. It can be seen from the figures that the activation energy of the composite electrolyte of Example 1 is 3.86 kJ / mol, and the activation energy of the composite electrolyte of Comparative Example 1 is 17.92 kJ / mol. That is, compared with the composite electrolyte with deep eutectic solvent as the lithium-ion conductor, the composite electrolyte with solvated ionic liquid as the lithium-ion conductor has a lower activation energy level, a lower potential barrier for lithium-ion transport in its electrolyte, and lithium ions are more easily transported.

[0051] As Figure 9 and Figure 10 shown, they are respectively the schematic diagrams of the rate performance of solid-state batteries using the composite electrolyte precursors of Example 1 and Comparative Example 1 at room temperature. Correspondingly, the rate performance data of the solid-state batteries using the composite electrolyte precursors of Example 1 and Comparative Example 1 at room temperature are shown in Table 1.

[0052] Table 1

[0053] From Figures 9-10 and Table 1, it can be seen that the rate performance of the solid-state batteries of Example 1 and Comparative Example 1 is similar at room temperature. However, compared with the battery using the composite electrolyte precursor of Comparative Example 1, the battery using the composite electrolyte precursor of Example 1 has a higher discharge specific capacity at low rates, indicating that the battery using the electrolyte of the present invention has a stronger energy output ability during discharge.

[0054] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A composite electrolyte precursor, characterized in that: It comprises a three-dimensional framework and a prepolymer solution loaded on the three-dimensional framework, wherein the prepolymer solution is obtained by mixing a solvated ionic liquid, a polymer matrix and an initiator; The three-dimensional skeleton is an aluminum oxide fiber membrane, and the polymer matrix is ​​polyethylene glycol diacrylate or vinylene carbonate.

2. The composite electrolyte precursor according to claim 1, characterized in that: The mass ratio of the solvated ionic liquid, the polymer matrix and the initiator is 2:(0.1747-0.8):(0.0124-0.0168).

3. The composite electrolyte precursor according to claim 1, characterized in that: The thickness of the three-dimensional skeleton is 100-200 μm, and the loading amount of the prepolymer on the three-dimensional skeleton is ≥ 0.174 mL / cm 2 .

4. The composite electrolyte precursor according to claim 1, characterized in that: The initiator includes one or more of azobisisobutyronitrile and ditoluoyl peroxide.

5. The composite electrolyte precursor according to any one of claims 1 to 4, characterized in that: The raw materials of the prepolymer solution also include additives, and the mass ratio of the solvated ionic liquid to the additive is 2:(0.3331-0.4225).

6. The composite electrolyte precursor according to claim 5, characterized in that: The additive includes one or more of fluoroethylene carbonate and hydrofluoroether.

7. A method for preparing a composite electrolyte precursor according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing a solvated ionic liquid, a polymer matrix and an initiator to obtain a prepolymer solution; (2) Infiltrating the three-dimensional skeleton into the prepolymer solution to obtain a composite electrolyte precursor.

8. The method for preparing a composite electrolyte precursor according to claim 7, characterized in that: The mixing is stirred at room temperature for 12-24 hours.

9. Use of the composite electrolyte precursor according to any one of claims 1 to 6 or the composite electrolyte precursor prepared by the method according to any one of claims 7 to 8 in a battery.

10. Use of the composite electrolyte precursor in a battery according to claim 9, characterized in that: The method comprises assembling the composite electrolyte precursor into a battery and performing an in-situ thermal polymerization reaction to obtain a battery; The in-situ thermal polymerization reaction is carried out at a temperature of 70-100° C. and for a time of 1-3 hours.

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