Composite gel polymer electrolyte, preparation method and battery containing composite gel polymer electrolyte

Abstract

The invention discloses a composite gel polymer electrolyte, a preparation method and a battery containing the composite gel polymer electrolyte. According to the invention, a novel gel polymer electrolyte (GPE) based on PVDF-HFP and LLZTO is prepared and researched. The novel composite gel polymer electrolyte shows high ionic conductivity of 1.1 * 10 <-3 > S / cm and a wide electrochemical stability window of 0-4V at room temperature. The first-circle discharge specific capacities of a solid-state battery using the novel GPE at 0.1 C, 0.2 C and 1C are respectively 156.2 mAh / g, 113.7 mAh / g and 90.1 mAh / g. The work of the invention can provide evidence for the first time to confirm that the inorganic particle LLZTO really contributes to and dominates the transmission of Li < + > in the PVDF-HFP / LLZTO mixed electrolyte composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a composite gel polymer electrolyte, a preparation method and a battery comprising the same. Background Art

[0002] Lithium metal is considered the best anode because of its high capacity and low potential, attracting more and more researchers' attention. However, the dendrite problem that occurs during the charge and discharge process of lithium metal batteries limits its widespread application. Solid electrolytes can inhibit the formation of lithium dendrites, making them an attractive alternative to liquid electrolytes.

[0003] Recently, GPEs (gel polymer electrolytes), as one of the solid electrolytes, have attracted more and more researchers' attention due to their good flexibility and excellent electrochemical performance. Most importantly, GPEs can effectively improve the safety of batteries by inhibiting the growth of dendrites. GPEs contain polymers, lithium salts, pastes, and liquid electrolytes. Generally, due to the presence of liquid electrolytes, GPEs exhibit high ionic conductivity at room temperature. Various polymer gels have been studied, such as polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), and polyethylene (PEO). Among polymer gels, PVDF-HFP is an important host for GPE because it has high ionic conductivity and a wide electrochemical stability window at room temperature. The low crystallinity of PVDF-HFP is the key to its high ionic conductivity, F - The strong electron-withdrawing effect of GPE gives it a high dielectric constant and a wide electrochemical stability window. However, the disadvantage of GPE is its low mechanical strength.

[0004] Adding ceramic particles to the gel polymer matrix is ​​a common method to improve the mechanical strength, such as Al2O3, SiO2, LLZO, LATP, etc. Many researchers have studied the effect of inorganic particles on GPE. The results show that the plasticization of ceramic particles can affect the recrystallization kinetics of polymer chains, inhibit the crystallization of polymers, and promote the movement of local amorphous regions of composite GPEs, which is beneficial to ion conduction. Among the additives that have been studied, garnet-type lithium ion conductors and glass-ceramics LLZTO show significant enhancements in ionic conductivity and electrochemical stability, as well as negligible electrical conductivity. In addition, LLZTO has a very high ionic conductivity (10 -3 Up to 10 -4 S / cm). By adding garnet ceramics, the ionic conductivity of the polymer electrolyte can be enhanced to 1.17×10 -4S / cm. In the composite electrolyte, lithium ions can be transported through the polymer matrix, inorganic fillers, organic-inorganic interface, or a combination of the three. The highest lithium ion transfer number of PEO / LLZO composite is 0.39. Therefore, the addition of garnet ceramics to GPE is a promising strategy to prepare composite electrolytes with high ionic conductivity, good electrochemical properties, and good thermal and mechanical stability. Summary of the invention

[0005] The object of the present invention is to provide a composite gel polymer electrolyte, a preparation method and a battery containing the same. The present invention prepares a composite gel polymer electrolyte with high ionic conductivity and good electrochemical performance by adding ceramic particles into a gel polymer matrix.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a method for preparing a composite gel polymer electrolyte, wherein the preparation method comprises the following steps:

[0008] PVDF-HFP and LLZTO(Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 ) adding the nanoparticle powder to an organic solvent, stirring at 20 to 35° C. for 10 to 24 hours, preferably at room temperature for 12 hours, to obtain a uniform solution;

[0009] The obtained uniform solution is then used to prepare a film on a substrate, and the obtained film is immersed in a liquid electrolyte for 12 to 48 hours to obtain a PVDF-HFP / LLZTO composite gel polymer electrolyte.

[0010] According to the preparation method of the present invention, preferably, the LLZTO (Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 )Nano-particle powders were synthesized by solid phase reaction method:

[0011] Dissolve LiOH·H2O, La2O3, ZrO2, Al2O3, and Ta2O5 in isopropanol and stir to form a uniform slurry; preferably stir for 5 to 10 hours to form a uniform slurry;

[0012] Then, the solvent in the obtained slurry is removed, and the slurry is heated at 800-1000° C. for 4-10 hours (preferably at 900° C. for 6 hours); then, the slurry is ground in isopropanol for 10-15 hours (preferably 13 hours), and dried to obtain the LLZTO nanoparticle powder.

[0013] Among them, LiOH·H2O, La2O3, ZrO2, Al2O3, Ta2O5 are prepared according to LLZTO (Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 ) is added according to the ratio of each metal element.

[0014] In the preparation process of the LLZTO nanoparticle powder, preferably, the step of removing the solvent from the obtained slurry specifically includes:

[0015] The solvent in the obtained slurry is evaporated at 80-90°C, for example, the solvent in the obtained slurry is evaporated at 85°C.

[0016] In the preparation process of the LLZTO nanoparticle powder, preferably, the drying is performed by heating in an oven.

[0017] According to the preparation method of the present invention, preferably, the mass ratio of the PVDF-HFP and LLZTO nanoparticle powders is 10:1.

[0018] According to the preparation method of the present invention, preferably, the organic solvent is acetone or N,N-dimethylformamide; more preferably, it is acetone.

[0019] According to the preparation method of the present invention, preferably, the step of using the obtained uniform solution to form a film on a substrate specifically comprises:

[0020] The obtained uniform solution is applied on a glass plate with a doctor blade and dried at 40 to 60°C for 20 to 30 hours to obtain a film, for example, at 50°C for 24 hours.

[0021] According to the preparation method of the present invention, preferably, the solute of the liquid electrolyte is LiPF6 (lithium hexafluorophosphate); the solvent of the liquid electrolyte is a mixed solvent of EC (ethylene carbonate) and DMC (dimethyl carbonate).

[0022] More preferably, the concentration of lithium hexafluorophosphate is 1.0 mol / L.

[0023] More preferably, the volume ratio of ethylene carbonate to dimethyl carbonate is 1:1.

[0024] In a preferred embodiment, the liquid electrolyte is 1.0 mol / L LiPF6 / EC-DMC 1:1 v / v. That is, the solute of the liquid electrolyte is 1.0 mol / L LiPF6 (lithium hexafluorophosphate); the solvent of the liquid electrolyte is a mixed solvent of EC (ethylene carbonate) and DMC (dimethyl carbonate), with a volume ratio of 1:1.

[0025] Another aspect of the present invention provides a composite gel polymer electrolyte obtained by the above preparation method.

[0026] Another aspect of the present invention provides a battery comprising the composite gel polymer electrolyte.

[0027] The present invention prepares and studies a novel gel polymer electrolyte (GPE) based on PVDF-HFP and LLZTO. The novel composite gel polymer electrolyte exhibits a conductivity of 1.1×10 -3 S / cm high ionic conductivity and a wide electrochemical stability window of 0-4V at room temperature. The solid-state battery using this new GPE has a first-cycle discharge capacity of 156.2mAh / g, 113.7mAh / g, and 90.1mAh / g at 0.1C, 0.2C, and 1C, respectively. The work of this invention can be said to be the first to provide evidence that the inorganic particle LLZTO does contribute and dominate the Li+ in the PVDF-HFP / LLZTO mixed electrolyte composite material. + transmission.

[0028] Figure 1 The molecular structure of PVDF-HFP and the relationship between PVDF-HFP and LLZTO in the composite gel polymer electrolyte are shown. LLZTO as a nanofiller is evenly dispersed in the PVDF-HFP membrane, which reduces the crystallinity of the polymer, which is beneficial to ion conduction. Moreover, the evenly distributed LLZTO nanoparticles enable the PVDF-HFP / LLZTO composite gel polymer electrolyte to transport lithium ions at any angle.

[0029] The good electrochemical performance of the battery using PVDF-HFP / LLZTO GPE is attributed to the good electrochemical and chemical properties of PVDF-HFP / LLZTO GPE. The excellent thermal stability, superb mechanical strength and outstanding electrochemical performance indicate that PVDF-HFP / LLZTO GPE has great advantages in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0031] Figure 2a and Figure 2b This is the SEM of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0032] Figure 2c This is an image of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0033] Figure 2d This is the XRD of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0034] Figure 3a The AC impedance of PVDF-HFP / LLZTO GPE at different temperatures

[0035] Figure 3b It is the Arrhenius plot of the PVDF-HFP / LLZTO GPE of the present invention in the range of room temperature to 90°C.

[0036] Figure 3c This is the DC polarization curve of Li / PVDF-HFP / LLZTO GPE / Li of the present invention at a polarization voltage of 0.1 V. The inset shows the EIS before and after polarization.

[0037] Figure 3d This is the LSV curve of the PVDF-HFP / LLZTO GPE of the present invention.

[0038] Figure 4a , Figure 4b and Figure 4c Battery performance of NCM811 / PVDF-HFP / LLZTO GPE / Li battery at room temperature: Figure 4a is the discharge capacity at different rates, Figure 4b The charge and discharge curves at different rates. Figure 4c This is the long cycle performance at 1C.

[0039] Figure 5a EIS graphs of NCM811 / PVDF-HFP / LLZTO GPE / Li battery before and after 30 cycles.

[0040] Figure 5b CV spectra of NCM811 / PVDF-HFP / LLZTO GPE / Li battery before and after 30 cycles.

[0041] Figure 6 This is the EDS test diagram of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0042] Figure 7a It is the DSC curve diagram of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0043] Figure 7b It is a TGA curve diagram of the PVDF-HFP / LLZTO composite gel polymer electrolyte of the present invention.

[0044] Figure 8This is the lithium stability test curve of Li|PVDF-HFP / LLZTO GPE|Li battery at room temperature.

[0045] Figure 9a and Figure 9b This is the SEM image of PVDF-HFP / LLZTO GPE in NCM811 / PVDF-HFP / LLZTO GPE / Li battery after 30 cycles. DETAILED DESCRIPTION

[0046] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0047] All numerical specifications herein (e.g., temperature, time, concentration, and weight, etc., including ranges for each thereof) are generally approximate values ​​that may be appropriately varied (+) or (-) in increments of 0.1 or 1.0. All numerical specifications may be understood as being preceded by the term "about."

[0048] Example 1

[0049] This embodiment prepares a PVDF-HFP / LLZTO composite gel polymer electrolyte, comprising the following steps:

[0050] (1)LLZTO(Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 ) Preparation:

[0051] LiOH·H2O, La2O3, ZrO2, Al2O3, and Ta2O5 were dissolved in isopropanol in proportion and stirred for 8 hours to obtain a uniform slurry, and then the solvent in the slurry was evaporated at 85°C; then heated at 900°C for 6 hours; after the heating, it was ground in isopropanol for 13 hours and heated and dried in an oven to obtain LLZTO nanoparticle powder.

[0052] (2) Preparation of PVDF-HFP / LLZTO composite gel polymer electrolyte:

[0053] 1g PVDF-HFP and 0.1g LLZTO nanoparticle powder were added to acetone and stirred at room temperature for 12 hours to obtain a uniform solution. The uniform solution was then applied to a glass plate with a scraper and dried at 50°C for 24 hours to obtain a membrane; the membrane was immersed in a liquid electrolyte (1.0mol / L LiPF6 / EC-DMC 1:1v / v) for 24 hours to obtain a composite GPE, namely PVDF-HFP / LLZTO composite gel polymer electrolyte (PVDF-HFP / LLZTO GPE).

[0054] Characterization and performance testing:

[0055] (1) Figure 2a and Figure 2b The SEM image of the obtained PVDF-HFP / LLZTO GPE is shown in Figure 2. The surface of the PVDF-HFP / LLZTO composite gel polymer electrolyte has many protrusions, and the small protrusions are the aggregation of LLZTO particles, which are evenly dispersed in the PVDF-HFP polymer. There are no obvious pores on the surface of the composite electrolyte membrane, which is different from the existing reported PVDF-HFP / LLZTO composite gel polymer electrolyte.

[0056] Figure 6 The EDS images show the uniform distribution of F, Zr, La, and Ta, confirming that LLZTO is well mixed and uniformly distributed in PVDF-HFP.

[0057] Figure 2c This is an image of PVDF-HFP / LLZTO GPE. After the PVDF-HFP / LLZTO composite membrane was immersed in liquid electrolyte for 12 hours, the PVDF-HFP / LLZTO GPE was transparent and soft. The liquid absorption rate of the composite electrolyte was 81%, and the high liquid absorption rate can ensure that it has high ionic conductivity.

[0058] The PVDF-HFP / LLZTO composite gel polymer electrolyte was tested by XRD to analyze its crystal structure. The results are shown in Figure 2d .from Figure 2d It can be seen that the diffraction peak of the ceramic particles is similar to that of garnet-type Li5LaNbO 3212 (LLNO), which means that the LLZTO nanoparticle powder prepared by the present invention is still in the garnet phase and has high ionic conductivity (10 -3 The two broad peaks at 2θ=18.1° and 20.1° indicate that PVDF-HFP has a crystalline phase. After the introduction of LLZTO as a nanofiller, the crystallinity of PVDF-HFP polymer decreases significantly. The decrease in the crystallinity of the polymer matrix and the increase in the amorphous region are beneficial to the transport of lithium ions.

[0059] (2) The thermal behavior of the PVDF-HFP / LLZTO composite gel polymer electrolyte was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

[0060] Figure 7a The DSC curve of the PVDF-HFP / LLZTO composite gel polymer electrolyte is shown. It can be seen from the DSC curve that there is an internal thermal peak at 141°C, which represents the glass transition of PVDF-HFP. Due to the addition of nanofiller LLZTO, the glass transition temperature is lower than that of pure PVDF-HFP. The lower glass transition temperature of the PVDF-HFP / LLZTO composite electrolyte means that its crystallinity is lower, the disorder of the polymer is increased, and the organic chain segments are more disordered and free, which is beneficial to Li + transmission.

[0061] like Figure 7b As shown in Figure 2, the PVDF-HFP / LLZTO composite gel polymer electrolyte has good thermal stability. However, due to the presence of water and solvent in the PVDF-HFP / LLZTO composite gel polymer electrolyte, 30% of the mass loss occurs before 350°C. Figure 7b As shown in the figure, the PVDF-HFP / LLZTO composite gel polymer electrolyte begins to decompose at 450°C, which is higher than the decomposition temperature of pure PVDF-HFP. The PVDF-HFP / LLZTO composite gel polymer electrolyte is almost completely decomposed at 500°C, with a total weight loss of 73%. The higher starting decomposition temperature means that the PVDF-HFP / LLZTO composite gel polymer electrolyte has better thermal stability.

[0062] (3) The ionic conductivity of the electrolyte is an important factor in judging the quality of lithium battery electrolyte. Figure 3a and Figure 3b The ionic conductivity of PVDF-HFP / LLZTO GPE in the temperature range of 25°C to 90°C is shown. The ionic conductivity of PVDF-HFP / LLZTO GPE at 25.9°C is 10 -3 S / cm, which is higher than the ionic conductivity of porous PVDF-HFP gel electrolyte. First, LLZTO nanoparticles can weaken the association effect of polymer cations and form an "ion-ceramic composite" system, thereby promoting the dissociation of lithium salts, increasing the number of free carriers, and weakening the O and Li +More importantly, the high absorption and low crystallinity of GPE with LLZTO also make lithium ions easier to transport. The ionic conductivity of PVDF-HFP / LLZTO GPE increases with increasing temperature. At 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃, the ionic conductivity of PVDF-HFP / LLZTO GPE is 1.1×10 -3 S / cm, 1.4×10 -3 S / cm, 1.8×10 -3 S / cm, 2.2×10 -3 S / cm, 2.3×10 -3 S / cm, 2.5×10 -3 S / cm, 2.7×10 -3 S / cm.

[0063] like Figure 3b As shown, the Arrhenius model is used to process the data, and the Ea of PVDF-HFP / LLZTO GPE is 19.15 kJ / mol, which is lower than that of PVDF-HFP. This means that Li + The energy barrier of the transfer is very low. This is attributed to the fact that LLZTO nanoparticles reduce the crystallinity of the system and create new Li + Transmission channel.

[0064] The lithium ion transfer number is used to describe the transfer ability of lithium ions in the electrolyte, which is an important parameter of solid electrolytes. The lithium ion transfer number is measured by combining AC impedance and DC polarization methods. The results are shown in Figure 3c , DC polarization curve of Li / PVDF-HFP / LLZTO GPE at a polarization voltage of 0.1V, and the inset shows the EIS before and after polarization. The calculated Li ion migration number of PVDF-HFP / LLZTO GPE is 0.736. The high Li ion migration number is due to the fact that the HFP group in PVDF-HFP / LLZTO has a strong electronegativity, which attracts and fixes the free anions in the electrolyte, increases the content of free lithium ions in the electrolyte, and the low crystallinity of the electrolyte is conducive to the movement of free lithium ions.

[0065] When GPE is used in batteries, its electrochemical stability is very important. When the battery is in use, the electrolyte must be chemically and electrochemically stable. Figure 3d The LSV of PVDF-HFP / LLZTO GPE is shown. Figure 3d As shown, the onset oxidation voltage of PVDF-HFP / LLZTO GPE is 4.0 V, and PVDF-HFP / LLZTO GPE is stable when cycled in the voltage range of 3-4.2 V.

[0066] (4) The present invention further evaluates the dynamic stability of the lithium / electrolyte interface by electrostatic cycling experiments. The results are shown in Figure 8 In this experiment, the constant current density is 0.1 mA / cm 2 , the Li|PVDF-HFP / LLZTO GPE|Li lithium symmetric battery is charged for 0.5 hours and discharged for 0.5 hours. Figure 8 As shown, the initial polarization voltage of the lithium symmetric battery is less than 30mV, and no short circuit occurs after 240 cycles. This shows that PVDF-HFP / LLZTO GPE has good stability to lithium. And PVDF-HFP / LLZTO GPE can also prevent the growth of lithium dendrites. In general, the above electrochemical data show that GPE has the potential to be used in solid-state lithium-ion batteries, giving it good rate and cycle performance.

[0067] (5) The present invention also applies PVDF-HFP / LLZTO GPE to lithium metal batteries, with NCM811 used as the cathode and metal lithium used as the anode. The battery is tested for rate and cycle performance at room temperature.

[0068] like Figure 4a and Figure 4b As shown in the figure, the initial discharge specific capacities of the battery using PVDF-HFP / LLZTO GPE at 0.1C, 0.2C and 1C are 156.2mAh / g, 113.7mAh / g and 90.1mAh / g respectively. The polarization voltage of the battery increases with the increase of charging and discharging rate, resulting in a decrease in the specific capacity of the battery, because Li + The diffusion rate at the interface is limited. Figure 4c As shown, after 100 cycles, the discharge capacity of the battery at 1C rate dropped to 32.3 mAh / g. This shows that the addition of LLZTO particles to GPE is very effective in inhibiting side reactions that lead to capacity decay. The good electrochemical performance of the battery using PVDF-HFP / LLZTO GPE is attributed to the good electrochemical and chemical properties of PVDF-HFP / LLZTO GPE. The excellent thermal stability, superb mechanical strength and outstanding electrochemical performance show that PVDF-HFP / LLZTO GPE has great advantages in practical applications.

[0069] (6) Electrochemical impedance spectroscopy and cyclic voltammetry were used to evaluate the stability of NCM811 / PVDF-HFP / LLZTO GPE / Li battery. Figure 5aThe EIS spectra of the NCM811 / PVDF-HFP / LLZTO GPE / Li battery before and after 30 cycles. The interfacial resistance and charge transfer resistance of the battery increase less with the cycle, indicating that the electrolyte / electrode interface and the passivation layer on the electrode are stable. The cyclic voltammograms of the battery before and after 30 cycles are shown in Figure 2. Figure 5b As shown, after 30 cycles, the current increased and the redox peak was no longer as obvious as before. Figure 9a and Figure 9b The SEM image of PVDF-HFP / LLZTO GPE in NCM811 / PVDF-HFP / LLZTO GPE / Li battery after 30 cycles shows that the morphology of GPE is flat without any pores. This indicates that PVDF-HFP / LLZTO GPE is stable and can prevent the formation of lithium dendrites.

[0070] In summary, the present invention prepares and studies a novel nanostructured carbon nanotube based on PVDF-HFP and Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 A new high-performance composite GPE with stable polarization of (LLZTO). LLZTO nanoparticles are embedded in GPE as active fillers to form a uniform PVDF-HFP / LLZTO composite gel polymer electrolyte. The mixed composite GPE exhibits a very stable polarization voltage, indicating that the electrolyte has high reversibility for metallic lithium and no obvious lithium dendrite formation. The solid-state lithium metal battery assembled using the new composite GPE has a high initial discharge specific capacity of 156.2mAh / g, 113.7mAh / g, and 90.1mAh / g at 0.1C, 0.2C, and 1C.

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a composite gel polymer electrolyte, wherein: The preparation method comprises the following steps: Add PVDF-HFP and LLZTO nanoparticle powders into an organic solvent and stir at 20 to 35° C. for 10 to 24 hours to obtain a uniform solution; The obtained uniform solution is then used to prepare a film on a substrate, and the obtained film is immersed in a liquid electrolyte for 12 to 48 hours to obtain a PVDF-HFP / LLZTO composite gel polymer electrolyte.

2. The preparation method according to claim 1, wherein The LLZTO nanoparticle powder was synthesized by solid phase reaction method: Dissolve LiOH·H2O, La2O3, ZrO2, Al2O3, and Ta2O5 in isopropanol and stir to form a uniform slurry; Then, the solvent in the obtained slurry is removed, and the slurry is heated at 800-1000° C. for 4-10 hours; then, the slurry is ground in isopropanol for 10-15 hours, and dried to obtain the LLZTO nanoparticle powder.

3. The preparation method according to claim 2, wherein The step of removing the solvent from the obtained slurry specifically comprises: evaporating the solvent from the obtained slurry at 80-90°C.

4. The preparation method according to claim 2, wherein The drying is performed by heating in an oven.

5. The preparation method according to claim 1, wherein The mass ratio of the PVDF-HFP and LLZTO nanoparticle powders is 10:

1.

6. The preparation method according to claim 1, wherein The organic solvent is acetone or N,N-dimethylformamide.

7. The preparation method according to claim 1, wherein The step of using the obtained uniform solution to form a film on a substrate specifically comprises: The obtained uniform solution was applied on a glass plate with a doctor blade, and dried at 40 to 60° C. for 20 to 30 hours to obtain a film.

8. The preparation method according to claim 1, wherein The solute of the liquid electrolyte is lithium hexafluorophosphate; the solvent of the liquid electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate.

9. The preparation method according to claim 8, wherein: In the liquid electrolyte, the concentration of lithium hexafluorophosphate is 1.0 mol / L.

10. The preparation method according to claim 8, wherein: The volume ratio of the ethylene carbonate to dimethyl carbonate is 1:

1.

11. A composite gel polymer electrolyte obtained by the preparation method according to any one of claims 1 to 10.

12. A battery comprising the composite gel polymer electrolyte according to claim 11.

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