Polymer electrolyte having three-dimensional network filler and method for preparing the same

Abstract

The application discloses a polymer electrolyte with three-dimensional network fillers and a preparation method thereof, and belongs to the technical field of lithium ion batteries. The application is based on a synergistic design concept of premixed filler guiding in-situ network growth, and hydrolysis of tetraethyl orthosilicate (TEOS) is regulated by formic acid. The premixed nano-SiO2 particles are used as nucleation sites to induce directional growth of SiO2 generated in-situ on the surface of the nano-SiO2 particles and mutual crosslinking, and the fillers form a three-dimensional crosslinked network structure in the polymer matrix. The application overcomes problems of easy agglomeration of fillers, incomplete crystallization inhibition and incomplete crosslinking of a single in-situ growth network due to lack of nucleation sites in a traditional physical blending method, and realizes synergistic enhancement of mechanical strength and ion transmission efficiency.

Description

Technical Field

[0001] This invention relates to a polymer electrolyte with a three-dimensional network filler and its preparation method, belonging to the field of lithium-ion battery technology. Background Technology

[0002] With the rapid development of the new energy vehicle industry and the continuous expansion of energy storage system application scenarios, the market has placed higher demands on the energy density, cycle life, and intrinsic safety of energy storage devices. Compared with the flammable organic electrolytes used in traditional liquid lithium-ion batteries, solid-state electrolyte lithium batteries have advantages such as high safety, strong ability to suppress lithium dendrites, and a wide electrochemical window, and are recognized as the core development direction of next-generation energy storage technology.

[0003] Among numerous solid-state electrolyte systems, polyvinylidene fluoride (PVDF) polymer electrolytes have become a research hotspot due to their advantages of high dielectric constant, good thermal stability, flexible interface, and low processing cost. However, the semi-crystalline nature of PVDF severely limits the migration ability of lithium ions (Li⁺), has poor compatibility with the lithium metal anode interface, and easily induces lithium dendrite growth and interfacial side reactions, leading to rapid degradation of battery cycle performance. To address these issues, the strategy of introducing inorganic fillers (such as SiO₂, Al₂O₃, TiO₂, etc.) into PVDF is commonly adopted. Currently, there are two main modification strategies to utilize filler-matrix interfacial interactions to suppress polymer crystallization, enhance mechanical strength, and construct additional ion transport channels. On the one hand, traditional simple physical blending methods easily lead to uneven filler dispersion and severe agglomeration, resulting in limited crystallization suppression effects, and the agglomerated interface can also form an ion transport bottleneck. On the other hand, in-situ polymerization methods are used to construct inorganic ceramic networks in PVDF, providing a new approach to improve filler dispersion and interfacial adhesion. For example, SiO2 generated in situ from the hydrolysis of tetraethyl orthosilicate (TEOS) can be used to construct a continuous three-dimensional ion transport framework. However, single in-situ networks still suffer from structural collapse or incomplete cross-linking due to a lack of sufficient nucleation sites to guide uniform growth, making it difficult to simultaneously optimize mechanical properties and ion transport efficiency. Therefore, achieving highly uniform dispersion of inorganic fillers and controllable construction of three-dimensional ion transport networks through reasonable structural control strategies is a key scientific approach to overcome the limitations of single modification methods and synergistically improve the electrochemical performance and mechanical stability of PVDF-based solid electrolytes. Summary of the Invention

[0004] Traditional modification strategies, such as introducing inorganic fillers (e.g., SiO2, Al2O3, TiO2) into the polymer matrix to suppress polymer crystallization or constructing an inorganic ceramic network in PVDF through in-situ polymerization, fail to balance mechanical stability and ion transport efficiency. Therefore, this invention proposes a filler with a three-dimensional cross-linked network structure within the polymer matrix. Specifically, nano-SiO2 particles are introduced into the PVDF polymer matrix as nucleation sites to guide the in-situ hydrolysis of TEOS to generate a SiO2 network that grows outwards. Ultimately, cross-linking occurs between these nucleation sites, resulting in a polymer solid electrolyte with a three-dimensional cross-linked network structure formed by the filler within the polymer matrix. This structure effectively disrupts the regular arrangement of PVDF segments through filler mixing, reducing the crystallinity of the polymer matrix. Furthermore, the continuous three-dimensional inorganic framework provides efficient lithium-ion transport channels, significantly improving the electrolyte's ion conductivity and structural stability.

[0005] This invention is achieved through the following technical solution: Nano-SiO2 particles and PVDF polymer matrix were weighed according to a preset ratio and added to a mixed solvent composed of acetone and N-methylpyrrolidone. The mixture was stirred on a magnetic stirrer at a specific temperature until the PVDF polymer matrix was completely dissolved. Then, a homogenizer was used for high-speed dispersion to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, measured amounts of formic acid and TEOS were added sequentially to the mixture, and stirring continued on a magnetic stirrer at a specific temperature to form a precursor solution. A measured amount of lithium bis(fluorosulfonyl)imide was then added to the precursor solution, and stirring continued to fully dissociate and uniformly disperse the lithium salt, yielding an electrolyte slurry with suitable flowability. After vacuum settling to remove bubbles, the slurry was uniformly coated onto the surface of aluminum foil using a doctor blade coating method. Vacuum drying was then performed to completely evaporate the solvent, resulting in a dense PVDF-based solid electrolyte membrane. Finally, the obtained electrolyte membrane was screened and cut into sheets to obtain a solid electrolyte that can be directly used for battery assembly. All processes were carried out in a glove box filled with Ar (O2 < 0.1 ppm, H2O < 0.1 ppm).

[0006] The specific preparation steps are as follows: (1) Weigh out a certain amount of nano-SiO2 particles and PVDF polymer matrix, and add them to a mixed solvent system composed of acetone and N-methylpyrrolidone (NMP). At 25°C... o C~ 60 o The mixture is stirred on a magnetic stirrer at C temperature for 6-12 hours until the PVDF polymer matrix is ​​completely dissolved. Then, it is dispersed at high speed using a homogenizer for 10-60 minutes to ensure the PVDF polymer matrix is ​​fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, measured amounts of formic acid and TEOS are added sequentially to the mixture, and the mixture is stirred at 25°C.o C~ 60 o Continue stirring on a magnetic stirrer for 6 to 12 hours at temperature C to form a precursor solution; (2) Add a quantitative amount of lithium bis(fluorosulfonyl)imide (LiFSI) to the precursor solution obtained in step (1), and heat at 25°C. o C~ 60 o Under C conditions, continue stirring on a magnetic stirrer for 12h to 36h to allow the lithium salt to fully dissociate and be uniformly dispersed in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) The electrolyte slurry obtained in step (2) is placed in a vacuum environment to stand and degas, so as to remove the air bubbles introduced during the stirring process. Then, the degassed slurry is evenly coated on the clean and dry aluminum foil surface using a scraper coating method, and then transferred to a vacuum oven and dried at 20°C. o C ~ 60 o Dry at C temperature for 24h ~ 48h to allow the solvent to fully evaporate and form a polymer solid electrolyte membrane with a smooth surface and dense structure; (4) The polymer solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a polymer solid electrolyte membrane that can be directly used for battery assembly is obtained.

[0007] The beneficial effects of this invention are as follows: By employing a coupled strategy of physical blending and in-situ growth, a filler with a three-dimensional cross-linked network structure is introduced into a PVDF polymer matrix, resulting in a structurally uniform and stable polymer solid electrolyte. First, nano-SiO2 particles are introduced into the polymer matrix using a physical blending method and dispersed using a high-speed disperser, ensuring the premixed nano-SiO2 particles are uniformly dispersed within the PVDF polymer matrix. Second, formic acid is used to rationally regulate the in-situ generation of SiO2 from TEOS hydrolysis. By controlling the ratio of formic acid to TEOS, the hydrolysis process is directionally regulated. The premixed nano-SiO2 particles serve as nucleation sites, inducing the SiO2 generated in-situ from TEOS hydrolysis to grow outwards from these nucleation sites. Ultimately, cross-linking occurs between these nucleation sites, forming a three-dimensional cross-linked network structure within the polymer matrix. Strict control of the hydrolysis rate and temperature enables precise regulation of the growth process of in-situ generated SiO2 at the nucleation sites. Premixed nano-SiO2 particles not only serve as nucleation sites for in-situ SiO2 network growth but also effectively disrupt the regular arrangement of polymer chains, reduce crystallinity, and provide some support to the polymer matrix. Formic acid is used to regulate the spread of the SiO2 network generated in-situ through TEOS hydrolysis, constructing a cross-linked network and continuous Li⁺ migration channels within the polymer matrix. The construction of this three-dimensional cross-linked network filler achieves a synergistic improvement in the mechanical strength and ion transport efficiency of the polymer solid electrolyte. Therefore, the synergistic design concept of premixed fillers guiding in-situ network growth provides a new approach for developing high-performance polymer-based solid electrolytes. Attached Figure Description

[0008] Figure 1 This is a scanning electron microscope image of the filler with a three-dimensional cross-linked network structure prepared in Example 1 of the present invention; Figure 2 The Li||Li symmetric battery assembled with the polymer solid electrolyte prepared in Example 2 of this invention operates at 0.2 mA cm⁻¹. -2 Constant current charge / discharge curves at current density; Figure 3 This is a graph showing the long-cycle capacity of a Li||solid electrolyte membrane||LFP full cell assembled with the polymer solid electrolyte prepared in Example 3 of this invention after 200 charge / discharge cycles at 1 C rate; Figure 4 The graph (a) and the corresponding long-cycle charge / discharge curve (b) are of the Li|| solid electrolyte membrane|| NCM811 full cell assembled with the polymer solid electrolyte prepared in Example 4 of this invention under long-cycle conditions of 30°C and 0.1C rate. Detailed Implementation

[0009] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0010] Example 1: A polymer electrolyte with a three-dimensional network filler and its preparation method: (1) Weigh 1.2 g of nano-silica (SiO2) particles and polyvinylidene fluoride (PVDF) polymer matrix, wherein the mass ratio of PVDF polymer matrix to SiO2 is 3:1, and add them to a mixed solvent system consisting of 4 mL of acetone and 4 mL of N-methylpyrrolidone (NMP). o The mixture was stirred on a magnetic stirrer at temperature C for 6 hours until the PVDF polymer matrix was completely dissolved. Then, it was dispersed at high speed for 10 minutes using a homogenizer to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, formic acid and tetraethyl orthosilicate (TEOS) were added sequentially to the mixture in the appropriate proportions, with a volume ratio of formic acid (0.2 mL) to TEOS of 1:1. The mixture was then stirred at 25°C. o Continue stirring on a magnetic stirrer for 6 hours at temperature C to form a precursor solution; (2) Add lithium bis(fluorosulfonyl)imide (LiFSI) to the precursor solution obtained in step (1), wherein the mass ratio of PVDF to LiFSI is 1:1, and heat at 25°C. o Under C conditions, the mixture was stirred on a magnetic stirrer for 24 h to allow the lithium salt to fully dissociate and be uniformly dispersed in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) The electrolyte slurry obtained in step (2) is placed in a vacuum environment and allowed to stand for 2 minutes to remove bubbles introduced during stirring. Then, the degassed slurry is evenly coated onto a clean and dry aluminum foil surface using a scraper coating method, and transferred to a vacuum oven. The oven is then set to 40°C. o Drying at C temperature for 48 h allows the solvent to fully evaporate, forming a PVDF-based solid electrolyte membrane with a smooth surface and dense structure; (4) The solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a PVDF-based solid electrolyte membrane that can be directly used for battery assembly is obtained.

[0011] The scanning electron microscope image of the PVDF-based solid electrolyte membrane prepared in this embodiment is shown below. Figure 1As shown in (a) and (b), a distinct three-dimensional cross-linked porous network structure is clearly observed. The premixed nano-SiO2 particles act as nucleation sites, guiding the uniform growth of the in-situ SiO2 network generated by hydrolysis to form a continuous three-dimensional network framework, rather than an isolated particle dispersion. The premixed nano-SiO2 particles, acting as nucleation sites, guide the in-situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS), forming a secondary SiO2 network. This dual-SiO2 system effectively disrupts the regular arrangement of polymer matrix (such as PVDF) chains, reducing its crystallinity and improving chain mobility. Simultaneously, the continuous three-dimensional cross-linked network structure provides a stable scaffold and improved transport efficiency for Li⁺. Furthermore, the cross-linked network imparts higher mechanical strength to the PVDF matrix, playing a crucial role in suppressing lithium dendrite growth and maintaining structural integrity during cycling.

[0012] Example 2: A polymer electrolyte with a three-dimensional network filler and its preparation method: (1) Weigh 1.2 g of nano-silica (SiO2) particles and polyvinylidene fluoride (PVDF) polymer matrix, wherein the mass ratio of PVDF polymer matrix to SiO2 is 6:1, and add them to a mixed solvent system consisting of 4 mL acetone and 4 mL N-methylpyrrolidone (NMP). o The mixture was stirred on a magnetic stirrer at temperature C for 6 hours until the PVDF polymer matrix was completely dissolved. Then, it was dispersed at high speed for 20 minutes using a homogenizer to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, formic acid and tetraethyl silicate (TEOS) were added sequentially to the mixture in the appropriate proportions, with a volume ratio of formic acid (0.2 mL) to TEOS of 2:1. The mixture was then stirred at 35°C. o Continue stirring on a magnetic stirrer for 6 hours at temperature C to form a precursor solution; (2) Lithium bis(fluorosulfonyl)imide (LiFSI) is added to the precursor solution obtained in step (1), wherein the mass ratio of PVDF to LiFSI is 5:1, and the solution is heated at 35°C. o Continue stirring on a magnetic stirrer for 24 hours at temperature C to allow the lithium salt to fully dissociate and disperse evenly in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) The electrolyte slurry obtained in step (2) was placed in a vacuum environment and allowed to stand for 5 minutes to remove air bubbles introduced during stirring. Then, the degassed slurry was evenly coated onto the clean and dry aluminum foil surface using a scraper coating method, and transferred to a vacuum oven. The oven was then set to 40°C. o Drying at C temperature for 48 h allows the solvent to fully evaporate, forming a PVDF-based solid electrolyte membrane with a smooth surface and dense structure; (4) The solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a PVDF-based solid electrolyte membrane that can be directly used for battery assembly is obtained.

[0013] In an argon-filled glove box (O2 content < 0.1 ppm, H2O content < 0.1 ppm), lithium sheets, solid electrolyte membranes, lithium sheets, spring contacts, and spacers were assembled into coin-type symmetrical cells using conventional methods. The cells were then tested at 0.2 mA cm⁻¹. -2 Constant current charge / discharge cycle tests were conducted at a current density, and the cycle performance is shown in the figure below. Figure 2 As shown in the figure, the solid electrolyte using a three-dimensional cross-linked network SiO2 filler exhibits stable electrochemical performance. This solid electrolyte membrane achieves a stability at 0.2 mA cm⁻¹. -2 It can be stably cycled for more than 1200 hours at a current density.

[0014] Example 3: A polymer electrolyte with a three-dimensional network filler and its preparation method: (1) Weigh 1.2 g of nano-silica (SiO2) particles and polyvinylidene fluoride (PVDF) polymer matrix, wherein the mass ratio of PVDF polymer matrix to SiO2 is 9:1, and add them to a mixed solvent system consisting of 4 mL acetone and 4 mL N-methylpyrrolidone (NMP). o The mixture was stirred on a magnetic stirrer at temperature C for 6 hours until the PVDF polymer matrix was completely dissolved. Then, it was dispersed at high speed for 30 minutes using a homogenizer to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, formic acid and tetraethyl silicate (TEOS) were added sequentially to the mixture in the appropriate proportions, with a volume ratio of formic acid (0.2 mL) to TEOS of 3:1. The mixture was then stirred at 60 °C. o Continue stirring on a magnetic stirrer for 6 hours at temperature C to form a precursor solution; (2) Add lithium bis(fluorosulfonyl)imide (LiFSI) to the precursor solution obtained in step (1), wherein the mass ratio of PVDF to LiFSI is 2:1, and heat at 60 °C. o Continue stirring on a magnetic stirrer for 24 hours at temperature C to allow the lithium salt to fully dissociate and disperse evenly in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) The electrolyte slurry obtained in step (2) was placed in a vacuum environment and allowed to stand for 15 minutes to remove bubbles introduced during stirring. Then, the degassed slurry was evenly coated onto a clean and dry aluminum foil surface using a scraper coating method and transferred to a vacuum oven. The oven was then set to 40°C. oDrying at C temperature for 48 h allows the solvent to fully evaporate, forming a PVDF-based solid electrolyte membrane with a smooth surface and dense structure; (4) The solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a PVDF-based solid electrolyte membrane that can be directly used for battery assembly is obtained.

[0015] In an argon-filled glove box (O2 content < 0.1 ppm, H2O content < 0.1 ppm), lithium iron phosphate (LFP), solid electrolyte membrane, lithium sheet, spring sheet, and gasket were assembled into a Li||solid electrolyte membrane||LFP full cell using conventional methods. The cell was subjected to long charge / discharge cycles at 30°C and 1C rate. The cycle performance is shown in the figure below. Figure 3 As shown in the figure, the initial discharge specific capacity of the Li||solid electrolyte membrane||LFP full cell is 160.6 mA hg. -1 After 200 cycles, the discharge specific capacity is 153.5 mA hg. -1 The capacity retention rate reached 95.6%.

[0016] Example 4: A polymer electrolyte with a three-dimensional network filler and its preparation method: (1) Weigh 1.2 g of nano-silica (SiO2) particles and polyvinylidene fluoride (PVDF) polymer matrix, wherein the mass ratio of PVDF polymer matrix to SiO2 is 6:1, and add them to a mixed solvent system consisting of 4 mL acetone and 4 mL N-methylpyrrolidone (NMP). o The mixture was stirred on a magnetic stirrer at temperature C for 6 hours until the PVDF polymer matrix was completely dissolved. Then, it was dispersed at high speed for 60 minutes using a homogenizer to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, formic acid and tetraethyl silicate (TEOS) were added sequentially to the mixture in the appropriate proportions, with a volume ratio of formic acid (0.2 mL) to TEOS of 5:1. The mixture was then stirred at 35°C. o Continue stirring on a magnetic stirrer for 6 hours at temperature C to form a precursor solution; (2) Add lithium bis(fluorosulfonyl)imide (LiFSI) to the precursor solution obtained in step (1), wherein the mass ratio of PVDF to LiFSI is 3:1, and heat at 35°C. o Continue stirring on a magnetic stirrer for 24 hours at temperature C to allow the lithium salt to fully dissociate and disperse evenly in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) The electrolyte slurry obtained in step (2) was placed in a vacuum environment and allowed to stand for 30 minutes to remove bubbles introduced during stirring. Then, the degassed slurry was uniformly coated onto a clean and dry aluminum foil surface using a scraper coating method, and transferred to a vacuum oven. The oven was then set to 40°C. o Drying at C temperature for 48 h allows the solvent to fully evaporate, forming a PVDF-based solid electrolyte membrane with a smooth surface and dense structure; (4) The solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a PVDF-based solid electrolyte membrane that can be directly used for battery assembly is obtained.

[0017] In an argon-filled glove box (O2 content < 0.1 ppm, H2O content < 0.1 ppm), lithium nickel cobalt manganese oxide (NCM811), solid electrolyte membrane, lithium sheet, spring sheet, and gasket were assembled into a Li||CPE||NCM811 full cell using conventional methods. Long-term cycling tests were conducted at 30°C and 0.1C rate. Figure 4 As shown in figure a, the initial discharge specific capacity reaches 179.6 mA hg. -1 After 100 cycles, the discharge specific capacity is 139.8 mA hg. -1 The capacity retention rate was ultimately 77.8%. Figure 4 b represents the long-cycle charge / discharge curve of the Li|| solid electrolyte|| NCM811 full cell. The charge / discharge curves show that the polarization of the full cell is relatively small. With the loss of electrolyte and positive electrode active material, the polarization gradually increases, but the increase is small, indicating that the entire battery system remains stable. The prepared solid electrolyte is well-suited to the lithium nickel cobalt manganese oxide positive electrode system.

[0018] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, modifications, substitutions, and variations can be made without departing from the spirit and principle of the present invention.

Claims

1. A polymer electrolyte with a three-dimensional network filler, characterized in that... By using premixed nano-silica particles as nucleation sites, the SiO2 network generated in situ by the hydrolysis of tetraethyl orthosilicate was guided to grow uniformly, thus constructing a polymer solid electrolyte with a three-dimensional cross-linked network structure.

2. The method for preparing the polymer electrolyte with a three-dimensional network filler as described in claim 1, characterized in that... The specific steps are as follows: (1) Weigh out a certain amount of nano-SiO2 particles and polyvinylidene fluoride (PVDF) polymer matrix, and add them to a mixed solvent system composed of acetone and N-methylpyrrolidone (NMP). At 25°C... o C ~ 60 o The mixture was stirred on a magnetic stirrer at C temperature for 6-12 hours until the PVDF polymer matrix was completely dissolved. Then, it was dispersed at high speed using a homogenizer to ensure the PVDF polymer matrix was fully dissolved and uniformly mixed with the nano-SiO2 particles. Subsequently, measured amounts of formic acid and TEOS were added sequentially to the mixture, and the mixture was stirred at 25°C. o C~60 o Continue stirring on a magnetic stirrer for 6 to 12 hours at temperature C to form a precursor solution; (2) Add a quantitative amount of lithium bis(fluorosulfonyl)imide LiFSI to the precursor solution obtained in step (1), and heat at 25°C. o C~ 60 o Continue stirring on a magnetic stirrer for 12 to 36 hours at temperature C to allow the lithium salt to fully dissociate and disperse evenly in the precursor solution, resulting in a homogeneous electrolyte slurry. (3) Place the electrolyte slurry obtained in step (2) in a vacuum environment and let it stand for 2-30 minutes to remove bubbles introduced during stirring. Then, use a scraper coating method to evenly coat the degassed slurry onto a clean and dry aluminum foil surface, and transfer it to a vacuum oven, set at 20°C. o C~ 60 o Dry at C temperature for 24h ~ 48h to allow the solvent to fully evaporate and form a polymer solid electrolyte membrane with a smooth surface and dense structure; (4) The polymer solid electrolyte membrane obtained in step (3) is subjected to appearance screening, and the defective parts are removed. It is then cut into circular membranes of the appropriate size according to the battery assembly requirements, and finally a polymer solid electrolyte membrane that can be directly used for battery assembly is obtained.

3. The method for preparing a polymer electrolyte with a three-dimensional network filler according to claim 2, characterized in that: In step (1), the mass ratio of PVDF polymer matrix to nano-SiO2 particles is 3:1 to 9:1, the volume ratio of formic acid to TEOS is 1:1 to 5:1, and the high-speed dispersion time is 10-60 min.

4. The method for preparing a polymer electrolyte with a three-dimensional network filler according to claim 2, characterized in that: In step (2), the mass ratio of PVDF to LiFSI is 1:1 to 5:1.

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