CN116722202B - A modified fluorinated polyolefin-based solid electrolyte and its preparation and application - Google Patents

Abstract

The present invention belongs to the field of solid electrolyte materials, and specifically relates to a method for preparing a modified fluoropolyolefin-based solid electrolyte, wherein a film to be treated is heated to a temperature T, and then placed in a cooling medium while hot for indirect quenching treatment to obtain the modified fluoropolyolefin-based solid electrolyte; the film to be treated comprises a fluoropolyolefin polymer substrate and components A, B and conductive lithium salt dispersed therein; the component A is a polymer modified with a hydroxyl group; the component B is a lithium ion conductor inorganic particle; the 0.5T0≤T<T0, and the T0 is the melting point temperature of the fluoropolyolefin polymer; the temperature of the cooling medium is ≤4°C. The method of the present invention can induce modification of the fluoropolyolefin active phase and improve its performance.

Description

A modified fluorinated polyolefin-based solid electrolyte and its preparation and application

Technical Field

The present invention relates to the field of battery materials, and in particular to the field of electrolyte technology for solid-state batteries.

Background Art

At present, lithium-ion batteries are widely used in people's lives. Traditional lithium-ion batteries use organic electrolytes, which are prone to leakage or even combustion and explosion during charging and discharging, posing great safety hazards. Solid-state batteries are considered to be the fundamental solution to this problem. Among them, fluorinated polyolefins such as typical PVDF, PVDF-HFP and other polymer-based solid electrolytes have become one of the widely studied solid electrolyte materials due to their excellent ionic conductivity, good flexibility and mechanical strength.

However, unlike other conventional polymer solid electrolyte matrices (such as PEO), fluorinated polyolefins contain multiple phase structures, but the content of active phases in existing fluorinated polyolefin solid electrolytes is generally not high, which hinders their performance. In addition, due to the advantages and disadvantages of the preparation methods, fluorinated polyolefin-based solid electrolytes may have large performance differences.

Summary of the invention

In order to solve the problem that fluorinated polyolefin-based solid electrolytes have less active phases, resulting in unsatisfactory electrochemical performance, the first purpose of the present invention is to provide a method for preparing a modified fluorinated polyolefin-based solid electrolyte, aiming to induce the formation of fluorinated polyolefin active phases and improve the electrochemical properties of the material.

The second object of the present invention is to provide a modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method and its application in solid-state batteries.

The third object of the present invention is to provide a solid-state battery comprising the modified fluorinated polyolefin-based solid electrolyte.

Different from conventional polymer substrates (such as PEO), fluorinated polyolefins have multiple phase structure types. The content of active phase structures suitable for the electrochemical performance of solid-state batteries in conventional fluorinated polyolefins is not ideal, which affects the electrochemical performance. To address this problem, the present invention provides the following improvement means, specifically:

A method for preparing a modified fluorinated polyolefin-based solid electrolyte, comprising heating a film to be treated to a temperature T, and then placing the film in a cooling medium while hot for indirect quenching treatment to obtain the modified fluorinated polyolefin-based solid electrolyte;

The film to be treated comprises a fluorinated polyolefin polymer substrate and component A, component B and a conductive lithium salt dispersed therein;

The component A is a polymer modified with hydroxyl groups;

The component B is lithium ion conductor inorganic particles (lithium-conducting inorganic particles);

The 0.5T0≤T<T0, wherein T0 is the melting point temperature of the fluorinated polyolefin polymer;

The temperature of the cooling medium is ≤4℃.

The present invention innovatively discovers that by innovatively heating the film to be treated to a non-melting state at temperature T and then conducting an indirect quenching treatment, and further coordinating the joint control of component A and component B and the cooling medium, synergy can be achieved, which can effectively induce and increase the content of the active phase structure of fluorinated polyolefins, thereby helping to improve the electrochemical properties of the prepared material.

In the present invention, the fluorinated polyolefin polymer is a polymer formed by polymerization of olefin monomers containing F. The F is directly modified on the polymer carbon chain, or modified on the polymer carbon chain by a fluorine-substituted alkyl. In a typical embodiment of the present invention, the fluorinated polyolefin polymer is at least one of PVDF and PVDF-HFP.

In the present invention, there is no particular requirement for the molecular weight of the fluorinated polyolefin polymer, as long as it meets the requirements for solid electrolyte film formation, and for example, it may be 100,000 to 1,000,000, and further may be 300,000 to 600,000.

The present invention has found that the film to be treated is innovatively heated to a temperature of T, so that it is indirectly quenched in a non-completely molten state. On this basis, the synergistic induction of components A and B and the joint control of the cooling medium can synergistically allow the formation of the active phase structure of the fluorinated polyolefin polymer and improve its content.

In the present invention, component A is a natural or polymerized polymer with hydroxyl groups modified on the polymer chain, preferably at least one of CMC and CMC-Li.

In the present invention, the component B is at least one of LLZTO, LLZO, LLTO, LGPS and LATP.

In the present invention, the conductive lithium salt may be a conventional lithium salt with conductivity in the industry, preferably at least one of LiTFSI, LiFSI, LiDFOB, and LiBOB.

In the present invention, the content of the components in the film to be treated can be adjusted as needed. For example, in the film to be treated, the weight ratio of the polymer substrate, the conductive lithium salt, the component A, the component B and is 1: 0.5-1: 0.01-0.1: 0.05-0.2; more preferably 1: 0.7-0.9: 0.02-0.08: 0.1-0.15; more preferably 1: 0.7-0.9: 0.04-0.06: 0.12-0.14; most preferably 1: 0.8-0.9: 0.04-0.05: 0.12-0.13. Studies have found that under the preferred ratio, a better synergistic effect can be obtained, which helps to further induce the formation of active phases and improve their performance.

In the present invention, the film to be treated can be prepared based on known coating methods, for example, fluoropolyolefin polymer, component A, component B and conductive lithium salt are slurried with a solvent, then coated on a mold and dried to form the film to be treated. The solvent is, for example, a solvent that can dissolve fluoropolyolefin polymer, for example, DMF, DMAC, NMP, etc. The mold has a flat surface and can further be a grinding tool with a smooth and flat surface. The material of the mold can be polymer, glass, steel, etc.

In the present invention, the film to be processed is sandwiched between the upper plane material and the lower plane material in advance, and then the subsequent indirect quenching treatment is performed. There is no special requirement for the material of the upper plane material and the lower plane material, as long as they can withstand high and low temperatures, for example, they can be glass or stainless steel. In the present invention, the film to be processed can be tightly sandwiched between the upper plane material and the lower plane material, and a gap of less than or equal to 1 mm is allowed between the upper plane material and the lower plane material and the film to be processed.

In the present invention, the indirect quenching treatment refers to the cooling medium and the film being separated by a barrier material and not in direct contact during the quenching stage.

The barrier material can be a conventional material that does not deform at the temperature, for example, a high temperature resistant film or stainless steel. The high temperature film refers to a film with a melting point temperature higher than 1.5 times T. The barrier material can be used to encapsulate the film to be treated before T treatment or after T insulation treatment, and then perform a subsequent indirect rapid cooling treatment. Considering the convenience of the treatment process, the film to be treated (including the overall material after the planar material clamping treatment) can be treated with a barrier material in advance, then heated to T, and placed in a cooling medium while hot for indirect quenching after insulation.

In the present invention, under the synergistic induction of the components A and B, and in combination with the control of the heating temperature T, the non-molten state to be treated can be quenched, which is beneficial to the synergistic effect of the components A and B to induce the formation of the active phase structure of the fluorinated polyolefin.

In the present invention, the T is 0.7 to 0.9T0. For example, when the fluorinated polyolefin is PVDF-HFP, the temperature of T can be 120 to 130°C.

Preferably, the holding time at temperature T is 5 to 10 minutes.

In the present invention, the cooling medium is any fluid or semi-fluid system with a temperature below 4°C. For example, the cooling medium is at least one of liquid nitrogen, liquid carbon dioxide, and liquid helium. In addition, it can also be water or a saline solution with a temperature below 0°C, and the salt can be, for example, conventional sodium chloride.

In the present invention, the amount of the cooling medium can be adjusted as required, for example, to be able to immerse the heat-conducting medium.

The present invention also provides a modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method.

In the present invention, based on the preparation method, the material can be endowed with a special phase structure and structural characteristics, and the material can exhibit better electrochemical properties.

The present invention also provides the application of the modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method, which is arranged between the positive electrode and the negative electrode to form a battery core of a solid-state battery.

In the present invention, the modified fluorinated polyolefin-based solid electrolyte of the present invention can be prepared into required solid-state battery components and materials based on the existing assembly method and principle of solid-state batteries.

For example, in the present invention, the positive electrode can be a conventional coated positive electrode, which includes a current collector and a positive electrode material composited on the surface of the current collector. The positive electrode material includes a positive electrode active material and selectively includes a binder and a conductive agent. The positive electrode active material is, for example, at least one of lithium iron phosphate, lithium cobalt oxide, and nickel cobalt manganese ternary. There is no special requirement for the element ratio between the nickel, cobalt and manganese, for example, it can be typical NCM523, NCM811, etc.

The negative electrode may be an active metal such as lithium metal, or may be a negative electrode containing at least one negative electrode active material selected from graphite and silicon;

The solid-state battery is a lithium-ion all-solid-state battery.

The present invention also provides a solid-state battery, which comprises the modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method of the present invention.

The solid-state battery of the present invention, except for using the modified fluorinated polyolefin-based solid electrolyte of the present invention as the electrolyte, other materials and component structures can be well-known.

Beneficial Effects

The present invention innovatively heats the film to be treated to a temperature of T, so that it is indirectly quenched in a non-completely molten state, and further cooperates with the synergistic induction of components A and B and the joint control of the cooling medium, which can synergistically induce the formation of active phase structure in the fluoropolyolefin polymer, which is beneficial to improving the electrochemical performance of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a SEM and image of the membrane to be treated (membrane prepared in step 1) and the membrane after modification in Example 1, wherein (a, c, e are the corresponding test images of the membrane to be treated; b, d, f are the corresponding test images of the membrane after modification);

FIG2 is an XRD diagram of the PVDF-HFP, the treated membrane and the modified membrane of Example 1;

FIG3 is an impedance diagram of the film to be treated and the modified film of Example 1;

FIG4 is an impedance diagram of the film to be treated and the modified film of Example 2;

FIG5 is a picture of the modified membrane of Comparative Example 5;

DETAILED DESCRIPTION

The specific steps of the present invention are described below by way of examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention in any way. Various processes and methods not described in detail in the present invention are conventional methods known in the art.

As an example of typical implementation, in the following cases, unless otherwise stated, the PVDF-HFP used has a MW of 455,000, is from Aladdin, and has a melting point (T0) of 140°C-145°C;

PVDF: from Aladdin, molecular weight ~400000; melting point (T0) 165 ~ 175 ° C.

In the following cases, the diaphragm to be treated is first fixed with a flat surface material before quenching (the interlayer gap is allowed to be less than or equal to 0.5 mm). In addition, the fixed diaphragm to be treated is pre-vacuum-packaged with a conventional vacuum packaging bag (such as a PA/PE composite vacuum bag to ensure that it does not melt or deform during the heat treatment stage), and then heated to T for insulation treatment and directly placed in a cooling medium while hot (maintained at a temperature of 0.9 to 1T) for indirect quenching.

In the present invention, each diaphragm can be assembled into an energy storage device based on known means, and an electrochemical performance test can be performed. For example, in the following case, the electrochemical test method is:

EIS impedance test: The impedance diagram of the electrolyte is measured by the electrochemical workstation, and the formula Calculate the ionic conductivity.

Lithium iron phosphate solid-state battery cycle performance test: Use lithium metal as the negative electrode, lithium iron phosphate as the positive electrode, and solid electrolyte as the separator and ion conductor to assemble button cells, and test the battery cycle performance through the battery test system. The temperature of the test process is 25℃.

Example 1

Step (1): Preparation of the membrane to be treated

0.45g polymer substrate (PVDF-HFP) and 0.4g LiTFSI were accurately weighed and added to a 20mL glass bottle, followed by 0.054g Li _6.4 La ₃ Zr _1.4 Ta _0.6 O ₁₂ ceramic powder (LLZTO; component B) and 0.02g CMC-Li (component A), and finally 6g dimethylacetamide solution. The glass bottle was then fully stirred at room temperature for 8h to obtain a uniform solid electrolyte slurry. The slurry was then evenly spread on a smooth flat mold of polytetrafluoroethylene, vacuum dried at 80℃ for 8h, and the solvent was evaporated and dried to form a film, thereby obtaining a PVDF-HFP-based solid electrolyte membrane (film to be treated), the microscopic morphology of which is shown in Figures 1a, 1c and 1e.

Step (2): Modification

The membrane to be treated was punched into a small disc with a diameter of 19 mm using a puncher, placed on a steel plate (the contact surface between the steel plate and the diaphragm was nearly flat) and pressed with a similar steel plate (the contact surface between the steel plate and the diaphragm was nearly flat), and finally sealed with a vacuum packaging bag. The oven temperature was raised to 128°C (marked as T), and the packaged steel plate was placed in the oven. After keeping the temperature for 8 minutes, it was immersed in liquid nitrogen while hot until the liquid nitrogen evaporated completely, and the modified electrolyte membrane (modified membrane, SEM and pictures are shown in Figures 1b, 1d and 1f) was obtained, and vacuum sealed.

X-ray diffraction analysis (XRD) is shown in Figure 2, which shows that the phase structure before and after treatment has undergone an ideal transformation.

EIS impedance test, through the formula The ionic conductivity was calculated to be 4.21×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 162mAh·g ^-1 , and the specific capacity retention rate reached 92% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 156mAh·g ^-1 , and the specific capacity retention rate reached 85% after 100 cycles.

Example 2

Compared with Example 1, the only difference is that the polymer substrate is PVDF, and other operations and parameters are the same as Example 1 (the ratio of the insulation time T and T0 is the same as Example 1).

The experimental results are as follows: X-ray diffraction analysis (XRD) shows an ideal phase transition similar to that of Example 1.

EIS impedance test, through the formula The ionic conductivity was calculated to be 2.16×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: Cycling at a rate of 0.2C, the first cycle is 154mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 84%; cycling at a rate of 0.5C, the first cycle is 142mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 80%.

Example 3

Compared with Example 1, the only difference is that the temperature of T is changed. The experimental groups are:

Group A: T is 0.7T0 (T0 is the average value of the melting point range of the polymer);

Group B: T is 0.8T0 (T0 is the average value of the melting point range of the polymer);

The results were as follows:

Group A: EIS impedance test, by formula The ionic conductivity was calculated to be 3.86×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 158mAh·g ^-1 , and the specific capacity retention rate reached 90% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 150mAh·g ^-1 , and the specific capacity retention rate reached 83% after 100 cycles.

Group B: EIS impedance test, by formula The ionic conductivity was calculated to be 3.9×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: Lithium iron phosphate solid-state battery cycle test: Cycling at a rate of 0.2C, the first cycle is 159mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 90.5%; cycling at a rate of 0.5C, the first cycle is 151mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 83.5%.

Example 4

Compared with Example 1, the only difference is that the contents of component A and component B are changed, and the experimental groups are:

Group A: only the amount of component B (LLZTO) was changed, which was 0.045 g (Group A1) and 0.063 g (Group A2).

Group B: only the amount of component A was changed, 0.01 g (Group B1) and 0.03 g (Group B2);

Group A: EIS impedance test, the ionic conductivity was 2.5×10 ^-4 S/cm and 2.6×10 ^-4 S/cm, respectively.

A1 group lithium iron phosphate solid-state battery cycle test: cycled at a rate of 0.2C, the first cycle was 150mAh·g ^-1 , and the specific capacity retention rate reached 86% after 100 cycles; cycled at a rate of 0.5C, the first cycle was 132mAh·g ^-1 , and the specific capacity retention rate reached 75% after 100 cycles.

Group B: EIS impedance test, the ionic conductivity was 3.1×10 ^-4 S/cm and 3.3×10 ^-4 S/cm, respectively.

B2 group lithium iron phosphate solid-state battery cycle test: cycled at a rate of 0.2C, the first cycle was 156mAh·g ^-1 , and the specific capacity retention rate reached 90% after 100 cycles; cycled at a rate of 0.5C, the first cycle was 149mAh·g ^-1 , and the specific capacity retention rate reached 82% after 100 cycles.

Example 5

Compared with Example 1, the only difference is that the cooling medium is a 15% sodium chloride aqueous solution at 0° C. Other operations and parameters are the same as those in Example 1.

EIS impedance test, ionic conductivity is 3.1×10 ^-4 S/cm

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 156mAh·g ^-1 , and the specific capacity retention rate reached 86% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 148mAh·g ^-1 , and the specific capacity retention rate reached 78% after 100 cycles.

Comparative Example 1

Compared with Example 1, the only difference is that LLZTO is missing, and other operations and parameters are the same as Example 1.

EIS impedance test shows that the ionic conductivity is 1.2×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 136mAh·g ^-1 , and the specific capacity retention rate reached 78% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 118mAh·g ^-1 , and the specific capacity retention rate reached 70% after 100 cycles.

Comparative Example 2

Compared with Example 1, the only difference is that an equal weight of lanthanum oxide is used to replace component B (LLZTO), and other operations and parameters are the same as Example 1.

The EIS impedance test was carried out according to the method of Example 1, and the ionic conductivity was 1.9×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 141mAh·g ^-1 , and the specific capacity retention rate reached 80% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 128mAh·g ^-1 , and the specific capacity retention rate reached 71% after 100 cycles.

Comparative Example 3

Compared with Example 1, the only difference is that CMC-Li is missing, and other operations and parameters are the same as Example 1.

EIS impedance test showed that the ionic conductivity was 2.3×10 ^-4 S/cm.

Lithium iron phosphate solid-state battery cycle test: When cycled at a rate of 0.2C, the first cycle was 139mAh·g ^-1 , and the specific capacity retention rate reached 82% after 100 cycles; when cycled at a rate of 0.5C, the first cycle was 127mAh·g ^-1 , and the specific capacity retention rate reached 74% after 100 cycles.

Comparative Example 4

Compared with Example 1, the only difference is that an equal weight of polyvinyl pyrrolidone is used to replace component A, and other operations and parameters are the same as Example 1.

The test result was as follows: the ionic conductivity was 4.6×10 ^-5 S/cm.

Lithium iron phosphate solid-state battery cycle test: Cycling at a rate of 0.2C, the first cycle is 88mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 50%; cycling at a rate of 0.5C, the first cycle is 64mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 30%.

Comparative Example 5

Compared with Example 1, the only difference is that T is 1.2 times T0 (T0 value is calculated based on the average melting point), and the PVDF-HFP is completely melted before subsequent quenching. The membrane image after other operations and parameters are the same as those in Example 1 is shown in FIG5 .

EIS impedance test, ionic conductivity is 1.1×10 ^-5 S/cm,

Lithium iron phosphate solid-state battery cycle test: Cycling at a rate of 0.2C, the first cycle is 61mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 46%; cycling at a rate of 0.5C, the first cycle is 40mAh·g ^-1 , and the specific capacity retention rate after 100 cycles is 28%.

Claims (25)

1. A method for preparing a modified fluorinated polyolefin-based solid electrolyte, characterized in that the film to be treated is heated to a temperature T, and then placed in a cooling medium while hot for indirect quenching treatment to obtain the modified fluorinated polyolefin-based solid electrolyte; The film to be treated comprises a fluorinated polyolefin polymer substrate and component A, component B and a conductive lithium salt dispersed therein; The component A is at least one of CMC and CMC-Li; The component B is inorganic particles of lithium ion conductor; The temperature T is greater than or equal to 0.5T0 and less than T0, and T0 is the melting point temperature of the fluorinated polyolefin polymer; The temperature of the cooling medium is ≤4℃. 2. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, wherein the fluorinated polyolefin polymer is a polymer formed by polymerization of F-containing olefin monomers. 3. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 2, wherein the fluorinated polyolefin polymer is at least one of PVDF and PVDF-HFP. 4. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 2, wherein the molecular weight of the fluorinated polyolefin polymer is 100,000 to 1,000,000. 5. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 4, wherein the molecular weight of the fluorinated polyolefin polymer is 300,000 to 600,000. 6. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, wherein the component B is at least one of LLZTO, LLZO, LLTO, LGPS, and LATP. 7. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, wherein the conductive lithium salt is at least one of LiTFSI, LiFSI, LiDFOB, and LiBOB. 8. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, characterized in that in the film to be treated, the weight ratio of the polymer substrate, the conductive lithium salt, the component A, and the component B is 1:0.5~1:0.01~0.1:0.05~0.2. 9. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 8, characterized in that in the film to be treated, the weight ratio of the polymer substrate, the conductive lithium salt, the component A, and the component B is 1:0.7~0.9:0.02~0.08:0.1~0.15. 10. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 8, characterized in that the fluorinated polyolefin polymer, component A, component B and conductive lithium salt are slurried with a solvent, then coated on a mold and dried to form the film to be treated. 11. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 10, characterized in that the mold is a mold with a flat surface. 12 . The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 11 , wherein the mold has a smooth and flat surface. 13. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, wherein the temperature T is 0.7 to 0.9T0; The holding time at temperature T is 5 to 10 minutes. 14. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, characterized in that the membrane to be treated is preliminarily sandwiched between an upper plane material and a lower plane material, and then a subsequent indirect quenching treatment is performed. 15 . The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 14 , wherein the upper plane material and the lower plane material are made of glass or stainless steel. 16. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 15, characterized in that a gap of less than or equal to 1 mm is allowed to exist between the upper plane material, the lower plane material and the diaphragm to be treated. 17. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, characterized in that the indirect quenching treatment means that the cooling medium and the membrane are separated by a barrier material and are not in direct contact during the quenching stage. 18. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 17, wherein the barrier material is a high temperature resistant film or stainless steel. 19. The method for preparing a modified fluorinated polyolefin-based solid electrolyte according to claim 1, wherein the cooling medium is at least one of liquid nitrogen, liquid carbon dioxide, liquid helium, and a saline solution below 0°C. 20. A modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to any one of claims 1 to 19. 21. An application of a modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to any one of claims 1 to 19, characterized in that it is arranged between a positive electrode and a negative electrode to form a battery core of a solid-state battery. 22. Use of the modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to claim 21, characterized in that the active material in the positive electrode is at least one of lithium iron phosphate, lithium cobalt oxide, and nickel-cobalt-manganese ternary. 23. Use of the modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to claim 21, characterized in that the negative electrode is lithium metal or a negative electrode containing at least one negative electrode active material selected from graphite and/or silicon. 24. Use of the modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to claim 21, characterized in that the solid-state battery is a lithium-ion all-solid-state battery. 25. A solid-state battery, characterized in that it comprises a modified fluorinated polyolefin-based solid electrolyte prepared by the preparation method according to any one of claims 1 to 19.