1. An all-solid polymer electrolyte is characterized by comprising a cross-linked polymer I, a cross-linked polymer II and lithium salt; the cross-linked networks formed by the cross-linked polymer I and the cross-linked polymer II are mutually penetrated; the cross-linked polymer I is obtained by polymerizing acrylic acid polyethylene glycol ester or methacrylic acid polyethylene glycol ester and diacrylic acid polyethylene glycol ester or dimethyl acrylic acid polyethylene glycol ester; the crosslinking polymer II is obtained by polymerizing diamino-terminated polyethylene glycol and an epoxy crosslinking agent.

2. The all-solid polymer electrolyte according to claim 1, characterized in that: the mass ratio of the cross-linked polymer I to the cross-linked polymer II is 1: 0.5-1: 2; the mol ratio of the ethylene oxide group to the lithium salt in the crosslinked polymer I and the crosslinked polymer II is 1: 1-24: 1.

3. The all-solid polymer electrolyte according to claim 1 or 2, characterized in that: the molar ratio of the acrylic acid polyethylene glycol ester or the methacrylic acid polyethylene glycol ester to the diacrylic acid polyethylene glycol ester or the dimethylacrylic acid polyethylene glycol ester is 50: 1-400: 1.

4. The all-solid polymer electrolyte according to claim 3, characterized in that: the number average molecular weight of the acrylic acid polyethylene glycol ester and the methacrylic acid polyethylene glycol ester is 130-1500; the number average molecular weight of the polyethylene glycol diacrylate and the polyethylene glycol dimethacrylate is 170-1500.

5. The all-solid polymer electrolyte according to claim 1 or 2, characterized in that: the molar ratio of amino in the diamino-terminated polyethylene glycol to epoxy in the epoxy group cross-linking agent is 1: 1-1: 2.

6. The all-solid polymer electrolyte according to claim 5, wherein: the number average molecular weight of the diamino-terminated polyethylene glycol is 500-10000; the epoxy crosslinking agent is an organic compound containing at least three epoxy groups.

7. The all-solid polymer electrolyte according to claim 1 or 2, characterized in that: the lithium salt is at least one of lithium bistrifluoromethanesulfonimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium perchlorate and lithium trifluoromethanesulfonate.

8. The method for producing an all-solid polymer electrolyte according to any one of claims 1 to 7, comprising the steps of:

1) dispersing diamino-terminated polyethylene glycol and an epoxy crosslinking agent in a solvent, and carrying out prepolymerization to obtain a prepolymer;

2) dispersing acrylic acid polyethylene glycol ester or methacrylic acid polyethylene glycol ester, diacrylic acid polyethylene glycol ester or dimethyl acrylic acid polyethylene glycol ester, an initiator and lithium salt in a solvent, adding the solvent into the prepolymer obtained in the step 1), and mixing to obtain a precursor solution;

3) and coating the precursor solution on a substrate, and polymerizing to obtain the all-solid-state polymer electrolyte.

9. The method for producing an all-solid polymer electrolyte according to claim 8, characterized in that: the prepolymerization in the step 1) is carried out at the temperature of 40-60 ℃, and the reaction time is 3-6 h; the polymerization in the step 3) is carried out in two steps, namely, the reaction is carried out for 2 to 4 hours at the temperature of between 70 and 90 ℃ and then for 12 to 30 hours at the temperature of between 110 and 130 ℃.

10. Use of the all-solid-state polymer electrolyte according to any one of claims 1 to 7 for the preparation of a lithium battery.

Background

With the development of society and the progress of science and technology, people have a sharp increase in the demand for energy, the transformation of energy and the upgrading of energy storage equipment are accelerated, and novel energy and high-power energy storage equipment become research hotspots. The lithium battery has the advantages of high charging and discharging efficiency, small self-discharge, environmental friendliness and the like, and occupies a huge market share. However, most of the currently commercially available lithium batteries are liquid electrolytes, which have great potential safety hazards, and generally adopt graphite cathodes, which have low energy density and are difficult to meet the application requirements of large-power vehicles and large-scale energy consumption equipment. Compared with a graphite cathode, the lithium metal cathode has the advantages of light weight, low reduction potential, high energy density, wide range of matched anodes and the like, and is favored by researchers, but the lithium dendrite problem (the lithium dendrite may pierce through a battery diaphragm to cause battery short circuit and have potential safety hazard) becomes a bottleneck limiting the practical application of the lithium metal cathode. Through intensive research on the cause and inhibition measures of lithium dendrites, researchers find that transformation of electrolyte systems is an important direction for the development of future battery systems, namely, replacement of conventional liquid electrolytes with solid electrolytes.

The polymer solid electrolyte has excellent comprehensive performance, good mechanical property, thermal stability and electrochemical property, and can promote the uniform deposition of lithium ions and effectively inhibit the growth of lithium dendrites by contacting with a stable interface of an electrode. The polyoxyethylene-based polymer solid electrolyte has the advantages of strong designability, excellent lithium salt dissolving performance, wide electrochemical window, hopeful matching with a high-voltage positive electrode and the like, and is widely researched, but the polyoxyethylene-based polymer solid electrolyte is easy to crystallize at room temperature and has lower ionic conductivity, and the actual application requirements are difficult to meet. In order to overcome the defects of the solid electrolyte of the polyethylene oxide polymer, various modification researches are widely carried out (such as filler addition, blending, copolymerization and the like), but the actually obtained effects are not satisfactory.

Therefore, there is a need for a crosslinked polymer solid electrolyte having good properties.

Disclosure of Invention

The invention aims to provide an all-solid-state polymer electrolyte and a preparation method and application thereof.

The technical scheme adopted by the invention is as follows:

the all-solid-state polymer electrolyte comprises a cross-linked polymer I, a cross-linked polymer II and lithium salt, wherein a cross-linked network formed by the cross-linked polymer I and the cross-linked polymer II penetrates through each other, the cross-linked polymer I is obtained by polymerizing polyethylene glycol acrylate or polyethylene glycol methacrylate and polyethylene glycol diacrylate or polyethylene glycol dimethacrylate, and the cross-linked polymer II is obtained by polymerizing diamino-terminated polyethylene glycol and an epoxy cross-linking agent.

Preferably, the mass ratio of the crosslinked polymer I to the crosslinked polymer II is 1: 0.5-1: 2.

Preferably, the molar ratio of the Ethylene Oxide (EO) group to the lithium salt in the crosslinked polymer I and the crosslinked polymer II is 1:1 to 24: 1.

Preferably, the molar ratio of the polyethylene glycol acrylate or methacrylate to the polyethylene glycol diacrylate or dimethacrylate is 50: 1-400: 1.

Preferably, the number average molecular weight of the polyethylene glycol acrylate and the polyethylene glycol methacrylate is 130-1500.

Preferably, the number average molecular weight of the polyethylene glycol diacrylate and the polyethylene glycol dimethacrylate is 170-1500.

Preferably, the molar ratio of the amino group in the diamino-terminated polyethylene glycol to the epoxy group in the epoxy group cross-linking agent is 1: 1-1: 2.

Preferably, the number average molecular weight of the diamino terminated polyethylene glycol is 500-10000.

Preferably, the epoxy-based crosslinking agent is an organic compound containing at least three epoxy groups.

More preferably, the epoxy crosslinking agent is trimethylolpropane triglycidyl ether2,4,6, 8-tetramethyl-2, 4,6, 8-tetrakis [3- (oxiranylmethoxy) propyl]CyclotetrasiloxaneAt least one epoxy-functionalized hexahedral silsesquioxane.

Preferably, the epoxy-functionalized hexahedral silsesquioxane has a structural formula:wherein R is

Preferably, the lithium salt is at least one of lithium bistrifluoromethanesulfonimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium perchlorate and lithium trifluoromethanesulfonate.

The preparation method of the all-solid-state polymer electrolyte comprises the following steps:

1) dispersing diamino-terminated polyethylene glycol and an epoxy crosslinking agent in a solvent, and carrying out prepolymerization to obtain a prepolymer;

2) dispersing acrylic acid polyethylene glycol ester or methacrylic acid polyethylene glycol ester, diacrylic acid polyethylene glycol ester or dimethyl acrylic acid polyethylene glycol ester, an initiator and lithium salt in a solvent, adding the solvent into the prepolymer obtained in the step 1), and mixing to obtain a precursor solution;

3) and coating the precursor solution on a substrate, and polymerizing to obtain the all-solid-state polymer electrolyte.

Preferably, the prepolymerization in the step 1) is carried out at the temperature of 40-60 ℃, and the reaction time is 3-6 h.

Preferably, the solvent in step 1) is at least one of tetrahydrofuran, dichloromethane, chloroform, toluene, benzene, dioxane and ethyl acetate.

Preferably, the initiator in step 2) is at least one of dicumyl peroxide (DCP), di-tert-butyl peroxide, tert-butyl hydroperoxide and cumene hydroperoxide.

Preferably, the solvent in step 2) is at least one of tetrahydrofuran, dichloromethane, chloroform, toluene, benzene, dioxane and ethyl acetate.

Preferably, the polymerization in the step 3) is carried out in two steps, namely, the reaction is carried out for 2 to 4 hours at the temperature of between 70 and 90 ℃ and then for 12 to 30 hours at the temperature of between 110 and 130 ℃.

The invention has the beneficial effects that: the all-solid-state polymer electrolyte has a double-crosslinking network formed by a soft crosslinking network and a hard crosslinking network which are mutually penetrated, has better capability of inhibiting the growth of lithium dendrites, has stable interface performance, wider electrochemical window, better mechanical property and thermal stability, can be matched with an active lithium metal cathode to prepare a lithium metal battery with high energy density, is favorable for promoting the development of high-power and high-energy storage equipment, and has wide application prospect.

Specifically, the method comprises the following steps:

1) the all-solid-state polymer electrolyte of the invention has a rigid-flexible combined double cross-linked network formed by a soft cross-linked network and a hard cross-linked network which are mutually penetrated, the two cross-linked networks are mutually penetrated to form a uniform amorphous system, the cross-linked density of the soft cross-linked network is lower, the main chain is softer, and Li is favorably used for Li⁺The ionic conductivity of the system can be further improved, the crosslinking density of the hard crosslinking network is higher, rigid support can be provided for a polymer system, and the system can be endowed with good mechanical properties;

2) the all-solid-state polymer electrolyte has good mechanical property and thermal stability, can form a stable contact interface with a positive electrode material and a lithium metal negative electrode, has good cycle performance and rate performance at medium and high temperature, does not contain organic liquid with poor thermal stability, has no liquid leakage phenomenon after being assembled into a battery, and has high safety;

3) the all-solid-state polymer electrolyte has good flexibility and stability to a lithium metal negative electrode, and can form a stable Solid Electrode Interface (SEI), so that the growth of lithium dendrites can be effectively inhibited, and a metal lithium battery with high stability is prepared;

4) the all-solid-state polymer electrolyte can be adjusted in performance by changing the molecular weight and the molar ratio of the polymerized monomer, and has higher designability and practical application value;

5) the all-solid-state polymer electrolyte has simple synthesis process, does not need special equipment, has low preparation cost and is suitable for industrial production.

Drawings

Fig. 1 is a schematic view of the microstructure of an all-solid polymer electrolyte according to the present invention.

Fig. 2 is a photograph of an all-solid polymer electrolyte in example 1.

Fig. 3 is an SEM image of an all-solid polymer electrolyte in example 1.

Fig. 4 is a graph showing the change of ionic conductivity with temperature of all-solid polymer electrolytes in example 1, comparative example 1 and comparative example 2.

Fig. 5 is an LSV curve of a lithium battery assembled with the all-solid polymer electrolyte of example 1.

Fig. 6 is an EIS curve of a lithium-lithium symmetric battery assembled with an all-solid polymer electrolyte in example 1.

FIG. 7 shows a lithium-lithium symmetric cell assembled with an all-solid polymer electrolyte in example 1 at 45 ℃ and 0.17mA/cm²The voltage versus time curve when a constant current cycling test is performed at a current density of (1).

Fig. 8 is a cycle performance curve of the all solid lithium metal battery assembled with the all solid polymer electrolyte of example 1 at different rates, which was measured at 45 c and a voltage range of 2.5V to 4.0V.

Fig. 9 is a photograph of an actual object of the all-solid polymer electrolyte in comparative example 2.

Detailed Description

The invention will be further explained and illustrated with reference to specific examples.

Example 1:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

1) mixing 84mg of diamino terminated polyethylene glycol with the number average molecular weight of 2000, 20mg of trimethylolpropane triglycidyl ether and 1mL of tetrahydrofuran (the molar ratio of amino in the diamino terminated polyethylene glycol to epoxy in the trimethylolpropane triglycidyl ether is 1:2), and reacting at 40 ℃ for 6 hours to obtain a prepolymer;

2) mixing 100mg of polyethylene glycol methacrylate with the number average molecular weight of 950, 0.2mg of polyethylene glycol dimethacrylate with the number average molecular weight of 550, 2mg of dicumyl peroxide, 70mg of lithium bistrifluoromethanesulfonimide and 2mL of tetrahydrofuran, adding the prepolymer obtained in the step 1), and uniformly mixing to obtain a precursor solution;

3) coating the precursor solution on a clean glass sheet, putting the glass sheet in a vacuum oven after the solvent is volatilized, firstly reacting for 3 hours at 80 ℃, and then reacting for 24 hours at 115 ℃ to obtain the all-solid-state polymer electrolyte (film-shaped, the thickness is about 300 mu m, and the extraction experiment result shows that the crosslinking efficiency is 82%; a schematic view of the microstructure of an all-solid polymer electrolyte is shown in fig. 1).

And (3) performance testing:

1) a photograph of a real object of the all-solid polymer electrolyte prepared in this example is shown in FIG. 2 (a and b in the drawing represent different photographing angles), and a Scanning Electron Microscope (SEM) image is shown in FIG. 3 (a and b in the drawing represent different magnifications).

As can be seen from fig. 2 and 3: the all-solid-state polymer electrolyte prepared by the embodiment has a flat and compact interior and no pores, and shows that a uniform and compact double-crosslinked network system is formed after two-step crosslinking polymerization reaction, and is beneficial to the conduction of lithium ions.

2) The all-solid-state polymer electrolyte prepared in this example was placed between two stainless steel electrodes, and the ionic conductivity thereof was measured with a Chenghua electrochemical workstation for the temperature-dependent change of ionic conductivity, and the obtained ionic conductivity-temperature-dependent change curve was shown in FIG. 4.

As can be seen from fig. 4: the ionic conductivity of the all-solid polymer electrolyte is continuously improved along with the temperature rise, and the ionic conductivity is 0.142mS/cm at 45 ℃.

3) The lithium metal sheet is used as a reference electrode, the stainless steel sheet is used as a working electrode, the all-solid-state polymer electrolyte prepared in the embodiment is used as an electrolyte, the electrolyte is packaged by a 2032 type button cell box, the electrochemical stability of the all-solid-state polymer electrolyte is tested by linear voltammetry scanning (LSV), the scanning range is 2V-6V, the scanning speed is 1mV/s, and the obtained LSV curve is shown in FIG. 5.

As can be seen from fig. 5: the all-solid-state polymer electrolyte has high electrochemical stability, the stable voltage of the all-solid-state polymer electrolyte can reach 4.2V, and the all-solid-state polymer electrolyte can meet the practical application under a wide electrochemical window.

4) The all-solid-state polymer electrolyte prepared in this example was placed between two lithium metal sheets, and packaged in a 2032-type coin cell case to obtain a lithium-lithium symmetric battery, and then the battery was stored at 45 ℃, and Electrochemical Impedance Spectroscopy (EIS) was performed at different times using chenhua electrochemical workstation, and the stability of the all-solid-state polymer electrolyte-metal lithium interface was tested, and the obtained EIS curve was shown in fig. 6.

As can be seen from fig. 6: all EIS curves have two semicircles, the first semicircle corresponds to the bulk resistance of the all-solid polymer electrolyte, and the second semicircle corresponds to the resistance of the all-solid polymer electrolyte-metal lithium interface; the bulk impedance of the all-solid-state polymer electrolyte does not change in the storage process, the interface impedance is reduced first and then is stable, the interface resistance is basically unchanged after 18 hours, and the interface resistance is still unchanged after the all-solid-state polymer electrolyte is stored for 9 days at 45 ℃, which indicates that the all-solid-state polymer electrolyte is stable to a metal lithium electrode.

5) The all-solid-state polymer electrolyte prepared in this example was placed between two lithium metal plates and fed into a 2032 button cell cartridgePackaging to obtain a lithium-lithium symmetric battery, and testing the symmetric battery at 45 deg.C and 0.17mA/cm with a blue battery testing system²The constant current cycle test was performed at a current density of (1), and 3h charging and 3h discharging were performed per cycle, and the obtained voltage change curve with time was as shown in fig. 7.

As can be seen from fig. 7: the voltage of the lithium-lithium symmetrical battery is relatively stable in each constant current cycle, which shows that lithium ions can be relatively uniformly reduced and deposited on the surface of a metal lithium electrode under the current density, and the voltage change between different cycles is not large, which shows that the all-solid-state polymer electrolyte is stable to the metal lithium, and the body resistance and the interface resistance of the all-solid-state polymer electrolyte are basically unchanged in the lithium ion deposition process. In addition, even if the lithium-lithium symmetric battery runs for 2600h in the constant-current cycle process, the situation (short circuit) that the voltage suddenly drops greatly does not occur, which indicates that the all-solid-state polymer electrolyte has excellent capability of inhibiting the growth of lithium dendrites, and the lithium-lithium symmetric battery does not have the phenomenon that the lithium dendrites penetrate through a diaphragm to cause battery short circuit in long-time running.

6) With LiFePO₄As a battery positive electrode (active material loading about 2 mg/cm)²The mass ratio of the components in the positive electrode LiFePO4 to the binder to the conductive carbon black is 60:32:8), the metal lithium is used as the negative electrode of the battery, the all-solid-state polymer electrolyte prepared in the embodiment is used as the diaphragm and the electrolyte to assemble the all-solid-state lithium metal battery, the cycle performance test is carried out at 45 ℃ in the voltage range of 2.5V-4.0V, and the obtained cycle performance curves under different multiplying powers are shown in figure 8.

As can be seen from fig. 8: the all-solid-state lithium metal battery has higher cycle capacity and retention rate, and the coulombic efficiency is higher than 99%.

Example 2:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

1) mixing 85mg of diamino terminated polyethylene glycol with the number average molecular weight of 6000, 6.5mg of trimethylolpropane triglycidyl ether and 1mL of tetrahydrofuran (the molar ratio of amino in the diamino terminated polyethylene glycol to epoxy in the trimethylolpropane triglycidyl ether is 1:2), and reacting at 50 ℃ for 3 hours to obtain a prepolymer;

2) mixing 100mg of polyethylene glycol methacrylate with the number average molecular weight of 950, 0.2mg of polyethylene glycol dimethacrylate with the number average molecular weight of 550, 2mg of dicumyl peroxide, 69mg of lithium bistrifluoromethanesulfonylimide and 2mL of tetrahydrofuran, adding the prepolymer obtained in the step 1), and uniformly mixing to obtain a precursor solution;

3) coating the precursor solution on a clean glass sheet, putting the glass sheet in a vacuum oven after the solvent is volatilized, firstly reacting for 3 hours at 80 ℃, and then reacting for 24 hours at 115 ℃ to obtain the all-solid-state polymer electrolyte (film-shaped, the thickness is about 150 mu m, and the extraction experiment result shows that the crosslinking efficiency is 75 percent; a schematic view of the microstructure of an all-solid polymer electrolyte is shown in fig. 1).

And (3) performance testing:

the all-solid-state polymer electrolyte prepared in the embodiment is placed between two stainless steel electrodes, and the ionic conductivity of the all-solid-state polymer electrolyte is tested by a Chenghua electrochemical workstation, so that the ionic conductivity of the all-solid-state polymer electrolyte at 35 ℃ is 0.030 mS/cm.

Example 3:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

1) 64mg of diamino-terminated polyethylene glycol having a number average molecular weight of 2000, 32mg of epoxy-functionalized hexahedral silsesquioxane (structural formula:r is) Mixing with 1mL of tetrahydrofuran (the molar ratio of amino in the diamino-terminated polyethylene glycol to epoxy in the epoxy-functionalized hexahedral silsesquioxane is 1:2), and reacting at 40 ℃ for 6 hours to obtain a prepolymer;

2) mixing 95mg of polyethylene glycol methacrylate with the number average molecular weight of 950, 0.2mg of polyethylene glycol dimethacrylate with the number average molecular weight of 550, 2mg of dicumyl peroxide, 60mg of lithium bistrifluoromethanesulfonimide and 2mL of tetrahydrofuran, adding the prepolymer obtained in the step 1), and uniformly mixing to obtain a precursor solution;

3) coating the precursor solution on a clean glass sheet, putting the glass sheet in a vacuum oven after the solvent is volatilized, firstly reacting for 3 hours at 80 ℃, and then reacting for 24 hours at 115 ℃ to obtain the all-solid-state polymer electrolyte (film-shaped, the thickness is about 150 mu m, and the extraction experiment result shows that the crosslinking efficiency is 82%; a schematic view of the microstructure of an all-solid polymer electrolyte is shown in fig. 1).

And (3) performance testing:

the all-solid-state polymer electrolyte prepared in the embodiment is placed between two stainless steel electrodes, the ionic conductivity of the all-solid-state polymer electrolyte is tested by a Chenghua electrochemical workstation, and the ionic conductivity of the all-solid-state polymer electrolyte at 45 ℃ is 0.127mS/cm, which can meet the requirement that the ionic conductivity of the all-solid-state polymer electrolyte reaches 10^-4Practical application requirements of S/cm.

Example 4:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

1) 76.4mg of diamino terminated polyethylene glycol with the number average molecular weight of 2000, 13.6mg of trimethylolpropane triglycidyl ether and 1mL of tetrahydrofuran are mixed (the molar ratio of amino in the diamino terminated polyethylene glycol to epoxy in the trimethylolpropane triglycidyl ether is 1:2), and the mixture is reacted for 6 hours at 40 ℃ to obtain a prepolymer;

2) mixing 89.4mg of polyethylene glycol acrylate with number average molecular weight of 480, 0.6mg of polyethylene glycol diacrylate with number average molecular weight of 550, 3mg of dicumyl peroxide, 59.5mg of lithium bistrifluoromethanesulfonylimide and 1mL of tetrahydrofuran, adding the prepolymer obtained in the step 1), and uniformly mixing to obtain a precursor solution;

3) coating the precursor solution on a clean glass sheet, putting the glass sheet in a vacuum oven after the solvent is volatilized, firstly reacting for 3 hours at 80 ℃, and then reacting for 24 hours at 115 ℃ to obtain the all-solid-state polymer electrolyte (film-shaped, the thickness is about 150 mu m, and the extraction experiment result shows that the crosslinking efficiency is 78%; a schematic view of the microstructure of an all-solid polymer electrolyte is shown in fig. 1).

And (3) performance testing:

the all-solid-state polymer electrolyte prepared in the embodiment is placed between two stainless steel electrodes, the ionic conductivity of the all-solid-state polymer electrolyte is tested by a Chenghua electrochemical workstation, and the ionic conductivity of the all-solid-state polymer electrolyte at 35 ℃ is 0.122mS/cm and the ionic conductivity of the all-solid-state polymer electrolyte at 100 ℃ is 1.65mS/cm, which shows that the all-solid-state polymer electrolyte has good thermal stability and higher ionic conductivity in a wide temperature range.

Comparative example 1:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

189mg of diamino terminated polyethylene glycol with the number average molecular weight of 2000, 40mg of trimethylolpropane triglycidyl ether, 73.3mg of lithium bistrifluoromethanesulfonimide and 3mL of tetrahydrofuran are mixed (the molar ratio of amino in the diamino terminated polyethylene glycol to epoxy groups in the trimethylolpropane triglycidyl ether is 1:2), then the mixture is coated on a clean glass sheet, after a solvent is volatilized, the mixture is placed in a vacuum oven, the reaction is carried out for 2h at 90 ℃, and then the reaction is carried out for 12h at 120 ℃, so that the all-solid polymer electrolyte is obtained.

And (3) performance testing:

the all-solid polymer electrolyte prepared in the comparative example was placed between two stainless steel electrodes, and the ionic conductivity thereof was measured according to the temperature change using Chenghua electrochemical workstation, and the obtained ionic conductivity curve according to the temperature change was shown in FIG. 4.

As can be seen from fig. 4: the ionic conductivity at 45 deg.C is 0.074mS/cm, less than 10^-4S/cm, the application requirement can not be met at the temperature, and although the all-solid-state polymer electrolyte prepared by the comparative example contains a hard cross-linked network and has higher mechanical modulus, the ionic conductivity of the all-solid-state polymer electrolyte is too low to meet the basic conditions of battery operation.

Comparative example 2:

an all-solid polymer electrolyte, the preparation method comprises the following steps:

200mg of polyethylene glycol methacrylate with the number average molecular weight of 950, 0.4mg of polyethylene glycol dimethacrylate with the number average molecular weight of 550, 3mg of dicumyl peroxide, 73mg of lithium bistrifluoromethanesulfonimide and 2mL of tetrahydrofuran are mixed, then the mixture is coated on a clean glass sheet, after a solvent is volatilized, the mixture is placed in a vacuum oven, and the mixture reacts for 24 hours at the temperature of 115 ℃, so that the all-solid-state polymer electrolyte is obtained.

And (3) performance testing:

1) the all-solid polymer electrolyte prepared in the comparative example was placed between two stainless steel electrodes, and the ionic conductivity thereof was measured according to the temperature change using Chenghua electrochemical workstation, and the obtained ionic conductivity curve according to the temperature change was shown in FIG. 4.

As can be seen from fig. 4: the all-solid polymer electrolyte prepared in this comparative example has higher ion conductivity over a wider temperature range than the all-solid polymer electrolyte in example 1, indicating that the soft cross-linked network is favorable for lithium ion conduction.

2) A photograph of a real object of the all-solid polymer electrolyte prepared in this comparative example is shown in FIG. 9 (a and b in the figure represent different photographing angles).

As can be seen from fig. 9: the all-solid polymer electrolyte prepared by the comparative example has high ionic conductivity, but has poor mechanical properties and cannot be in a self-supporting state.

Tests have found that a lithium-lithium symmetrical battery or a solid-state LiFePO in which the all-solid-state polymer electrolyte prepared in the comparative example is used as a separator and electrolyte assembly₄The Li battery can directly generate a short circuit phenomenon, and related tests cannot be carried out.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.