Surface salt segregation polymer electrolyte and its preparation method and application

Abstract

The present invention discloses a surface salt segregation polymer electrolyte and its preparation method and application, which belongs to the field of solid-state and semi-solid-state battery technology. The surface salt segregation polymer electrolyte of the present invention has the characteristic of surface salt enrichment. The preparation method of the salt segregation polymer electrolyte of the present invention comprises the following steps: first, a high molecular skeleton polymer, a solute salt or / and a filler powder are added to a mixed solvent composed of a low boiling point, high polymer solubility solvent and a high boiling point, high salt solubility, low polymer solubility solvent, and all the components are mixed by stirring, homogenizing, or ball milling. The obtained casting solution is cast into a film, or cast, coated or applied on a porous support membrane, and dried to obtain a polymer electrolyte. The polymer electrolyte prepared by the present invention has the characteristic of a salt-enriched surface, can realize efficient ion transport in the electrolyte, generate an interface layer with low impedance and high stability on the surface of the negative electrode, inhibit side reactions, and improve the comprehensive performance of the solid-state battery.

Description

Technical Field

[0001] The present application belongs to the field of solid-state and semi-solid-state battery technology, and specifically relates to surface salt segregation polymer electrolytes and preparation methods and applications thereof. Background Art

[0002] Currently developed high-energy-density electrochemical energy storage systems, such as lithium-ion batteries, mostly use organic liquid electrolytes, which have advantages such as good wettability and high ionic conductivity. However, in the pursuit of safer and higher-energy-density electrochemical energy storage systems, the solidification of electrolytes is a major trend in future battery development. Solid electrolytes, as a bridge for ion transfer between the positive and negative electrodes, are the core components of solid-state batteries. Their properties are key factors that significantly affect the reversible capacity, safety, and cycle life of all-solid-state batteries.

[0003] Among the numerous solid-state electrolytes reported, polymer electrolytes have attracted considerable attention due to their excellent ductility, close interfacial contact, and facile fabrication techniques, and are considered ideal solid electrolytes for the development of solid-state batteries. However, their low room-temperature ionic conductivity severely limits their practical application. To date, research on polymer electrolytes has primarily focused on optimizing the polymer backbone structure, component types, and ratios. By manipulating polymer crystallinity, glass transition temperature, and mesostructure, these efforts aim to enhance the complexation / dissociation rates of cations between segments or form fast ion transport networks, resulting in a high degree of compositional uniformity. Alternatively, research has focused on constructing interlayer or mixed-phase structures, achieving balanced electrochemical performance and mechanical strength through the simple stacking and mixing of multiple components with different polymer types or filler concentrations. This composite approach results in high ion migration barriers at the interfaces between the different components, making chemical degradation or stress changes during battery charge and discharge processes susceptible to delamination of the two phases.

[0004] In fact, the decomposition of small molecule salts is an important source of components in the positive and negative electrode interface layers (CEI, SEI). Increasing the concentration of salts participating in the interfacial reaction is conducive to the formation of CEI / SEI membranes with high mechanical strength, high ion flux, and high electrochemical stability, ensuring the efficient operation of the battery. Similar high-concentration salt systems such as "salt-in-polymer" have been reported. Excessive overall salt concentration will lead to reduced mechanical strength and increased viscosity of the electrolyte. While the electrolyte and electrode are in closer contact, it also increases the difficulty of battery processing. During battery operation, the growth of dendrites of the metal negative electrode (such as metallic lithium and sodium) is difficult to suppress, which in turn induces short-circuit failure of the battery. Therefore, it is particularly important to study the thermodynamic and kinetic behavior of the solute salt distribution during the casting process of polymer solid electrolyte films and to achieve a continuous concentration distribution of the solute salt at its surface interface and bulk. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a surface salt segregation polymer electrolyte and its preparation method and application in solid-state batteries and semi-solid-state batteries. The present invention utilizes the boiling point, volatility, and solubility differences of different solvents for polymers and solute salts. During the film formation process, due to the differences in the physical and chemical properties of different solvents, as the solvent volatilizes along the gradient, the solute salt is locally enriched in the high-boiling point solvent. The dried product has the characteristics of surface salt segregation. Combined with the traditional sol drying film forming method, the preparation method of the surface salt segregation polymer electrolyte of the present invention is obtained. The preparation method of the present invention has the characteristics of low energy consumption and easy processing. Assembling the solid electrolyte into a solid-state battery can achieve long-term and stable operation of the battery.

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

[0007] In a first aspect, the present invention provides a surface salt segregation polymer electrolyte, wherein the polymer electrolyte has the characteristics of surface salt segregation and has both excellent ionic conductivity and mechanical properties.

[0008] In a second aspect, the present invention provides a method for preparing a surface salt segregation polymer electrolyte, comprising the following steps:

[0009] S1: adding a mixed solvent consisting of a low-boiling-point, high-polymer-solubility solvent and a high-boiling-point, high-salt-solubility, low-polymer-solubility solvent to the high-molecular-weight skeleton polymer, solute salt, and / or filler powder, and uniformly mixing all the components by stirring, homogenizing, or ball milling to obtain a target casting solution;

[0010] S2: Casting the casting solution obtained in step S1 into a film, or casting, coating or applying it on a porous support membrane;

[0011] S3: Drying the film obtained in step S2 to obtain a polymer electrolyte.

[0012] Based on the above technical solution, further, in step S1, the mass ratio of the high molecular skeleton polymer, the solute salt and the filler powder is (0.2-20):1:(0-1), preferably (0.5-4):1:(0-0.5).

[0013] Based on the above technical solution, further, the high molecular skeleton polymer described in step S1 includes but is not limited to polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polysulfone, polyphenylene ether, polyether, polyester, rubber elastomer, fluoropolyester, fluororubber elastomer, fluoropolysulfone, fluoropolyphenylene ether, fluoropolyether, fluoropolyester, fluororubber elastomer, etc., or a combination of one or more of them.

[0014] Based on the above technical solution, further, the cations in the solute salt described in step S1 include but are not limited to lithium ions (Li + ), sodium ion (Na + ) or potassium ions (K + ), anions include but are not limited to bis(trifluoromethanesulfonyl)imide (TFSI - ), bis(fluorosulfonyl)imide (FSI - ), trifluoromethanesulfonyl (OTf-), perchlorate (ClO4 - ), tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroarsenate (AsF6 - ), nitrate (NO3 - ), bis(oxalatoborate) (BOB - ), difluorooxalate boric acid (ODFB - ) or a combination of two or more.

[0015] Based on the above technical solution, further, the filler powder described in step S1 includes but is not limited to one or a combination of two or more of inorganic solid electrolytes, metal organic framework compounds (MOFs) or other ion transport inert materials.

[0016] Based on the above technical solution, further, the filler powder described in step S1 is preferably Na3Zr2Si2PO 12 、Li 6.25 Al 0.25 La3Zr2O 12 .

[0017] Based on the above technical solution, further, the boiling point difference between the low boiling point solvent and the high boiling point solvent in step S1 is higher than 5°C, preferably ≥50°C; the volume ratio of the low boiling point solvent to the high boiling point solvent is (0.5~1000):1, preferably (1~100):1.

[0018] Based on the above technical solution, further, the low boiling point solvent in step S1 includes but is not limited to methanol, ethanol, propanol, N,N-dimethylformamide, butyronitrile, acetone, tetrahydrofuran, etc., and the high boiling point solvent includes but is not limited to propylene carbonate, triethyl fluorophosphate (FTEP), fluoroethylene carbonate (FEC) or trifluoromethylethylene carbonate (TFEC), etc.

[0019] Based on the above technical solution, further, the solid content of the casting solution in step S1 is 5 to 90 wt %.

[0020] Based on the above technical solution, further, the porosity of the porous support membrane in step S2 is 10-98%, and the body material is polyethylene (PE), polypropylene (PP), polyimide (PI) or a composite polymer material.

[0021] Based on the above technical solution, further, the drying time in step S3 is 10 minutes to 72 hours, and a step-by-step drying program can be set.

[0022] In a third aspect, the present invention provides the above-mentioned surface salt segregation polymer electrolyte and the surface salt segregation polymer electrolyte prepared by the above-mentioned preparation method for use in solid-state batteries and semi-solid-state battery systems.

[0023] Based on the above technical solution, it further includes primary batteries, secondary batteries, ion batteries, metal batteries, etc.

[0024] Based on the above technical solution, the solid-state battery and semi-solid-state battery are further applied to portable electronic products, or to transportation equipment such as electric vehicles and drones, or to large-scale energy storage power stations.

[0025] The preparation method of the present invention and the obtained product have the following advantages and beneficial effects:

[0026] (1) The present invention utilizes the differences in the physical and chemical properties of different solvents to achieve the enrichment of small molecule salts on the surface of the polymer electrolyte through a simple surface salt segregation process, thereby forming CEI and SEI layers rich in inorganic components on the electrode surface, thereby improving the interface stability of the solid electrolyte-electrode.

[0027] (2) The salt-enriched surface achieved by the surface polymer electrolyte salt segregation method proposed in the present invention is a dense membrane structure, and the composition changes continuously from the surface to the bulk phase, which is not easy to produce holes or phase separation. While forming a tight and stable interfacial contact, it retains the excellent mechanical properties of the low-solvent, low-salt content bulk electrolyte, and the prepared solid-state battery has excellent comprehensive performance.

[0028] (3) The method for surface salt segregation of polymer electrolytes proposed in the present invention is simple to operate, has low synthesis cost, low energy consumption, is environmentally friendly, is suitable for practical application in solid-state batteries, and is conducive to industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0030] Figure 1 Schematic diagram of the production of the surface salt segregation polymer electrolyte membrane of the present invention.

[0031] Figure 2 The time-of-flight secondary ion mass spectrometry test of the surface salt segregation polymer electrolyte membrane obtained in Example 1 is CF3SO2 - 3D rendering of .

[0032] Figure 3 Time-of-flight secondary ion mass spectrometry test of the surface salt segregation polymer electrolyte membrane obtained in Comparative Example 1 CF3SO2 - 3D rendering of .

[0033] Figure 4 This is a scanning probe microscope image of the surface salt segregation polymer electrolyte membrane obtained in Example 1. The particles in the image are inorganic fillers.

[0034] Figure 5 Graph showing the change in ionic conductivity of the surface salt segregation polymer electrolyte membrane obtained in Example 1 with temperature.

[0035] Figure 6 The sodium / sodium symmetric battery assembled using the surface salt segregation polymer membrane obtained in Example 1 was tested at 0.5 mA cm -2 Current density, 0.5 mAh cm -2 Sodium stripping / deposition cycle curve at the areal capacity.

[0036] Figure 7 The sodium / sodium symmetric battery assembled using the surface salt segregation polymer membrane obtained in Example 1 was -2 Current density, 1 mAh cm -2 Sodium stripping / deposition cycle curve at the areal capacity.

[0037] Figure 8 This is a rate performance diagram of a sodium iron pyrophosphate / sodium solid-state battery assembled using the surface salt segregation polymer membrane obtained in Example 1 of the present invention.

[0038] Figure 9 This is a cycling performance diagram of a Na / sodium iron pyrophosphate solid-state battery assembled using the surface salt segregation polymer membrane obtained in Example 1 at a current density of 1C. DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0040] Example 1

[0041] This embodiment provides a method for preparing a surface salt segregation polymer electrolyte membrane, comprising the following steps:

[0042] (1) Dissolve 0.5 g of polyvinylidene fluoride (PVDF) powder and 0.352 g of sodium bis(fluorosulfonyl)imide (NaFSI) in 6 mL of anhydrous N,N-dimethylformamide (DMF), stir at 60 °C for 1 h to dissolve, and add 0.1 g of Na3Zr2Si2PO 12 Nanopowder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd.) was stirred continuously at room temperature for 3 h until the nanoparticles were uniformly dispersed in the solution;

[0043] (2) Add 0.65 mL of trifluoromethyl ethylene carbonate (TFEC) solvent to the dispersion obtained in step (1) above, and continue stirring for 1 h until all components are evenly mixed;

[0044] (3) The casting mixture obtained in step (2) was cast into a film in an argon atmosphere glove box, transferred to a vacuum drying oven, and vacuum dried at 65°C for 24 hours. After drying, the resulting film thickness was 40 μm. The film was cut into circular polymer electrolyte membranes with a diameter of 19 mm in the glove box.

[0045] Time-of-flight secondary ion mass spectrometry test of the surface salt segregation polymer electrolyte membrane obtained in Example 1 CF3SO2 - The 3D rendering of Figure 2 As shown in the figure, CF3SO2 - For FSI - Mass spectrometry dissociation products, the color depth in the figure represents CF3SO2 - The darker the surface, the higher the concentration, which means that NaFSI is enriched on the surface of the material membrane. Figure 4 As shown, Figure 2 and Figure 4 The results show that the polymer electrolyte membrane obtained in Example 1 has surface segregation of NaFSI salt and a dense membrane structure.

[0046] Example 2

[0047] This embodiment provides a method for preparing a surface salt segregation polymer electrolyte membrane, comprising the following steps:

[0048] (1) Dissolve 0.5 g PVDF powder and 0.352 g NaFSI in 6 mL of anhydrous N,N-dimethylformamide (DMF), stir at 60 °C for 1 h to dissolve, and add 0.1 g Na3Zr2Si2PO 12 Nanopowder was stirred continuously at room temperature for 3 h until the nanoparticles were evenly dispersed in the solution;

[0049] (2) Add 0.65 mL of trifluoromethyl ethylene carbonate (TFEC) solvent to the dispersion obtained in step (1) above, and continue stirring for 1 h until all components are evenly mixed;

[0050] (3) In an argon atmosphere glove box, the casting mixture obtained in step (2) was coated onto a porous polypropylene (PP) membrane with a porosity of 70% (pore diameter approximately 1 μm, thickness approximately 10 μm). After drying, the membrane was coated on the other side (coating process was the same as above) and vacuum dried at 65°C for 24 h. After drying, the membrane had a thickness of 35 μm and was cut into circular polymer electrolyte membranes with a diameter of 19 mm.

[0051] Example 3

[0052] This embodiment provides a method for preparing a surface salt segregation polymer electrolyte membrane, comprising the following steps:

[0053] (1) 0.5 g of polyethylene oxide (PEO) powder and 0.352 g of NaFSI were dissolved in 6 mL of anhydrous butyronitrile and ball milled at 300 rpm for 2 h. 0.1 g of Na3Zr2Si2PO4 was added. 12 The nanopowder was ball-milled for 3 h until a uniformly dispersed solution was obtained;

[0054] (2) Add 0.65 mL of triethyl fluorophosphate (FTEP) solvent to the dispersion obtained in step (1) above, and continue ball milling for 1 h until all components are uniformly mixed;

[0055] (3) The casting mixture obtained in step (2) was cast into a film in an argon atmosphere glove box, transferred to a vacuum drying oven, and vacuum dried at 65°C for 30 hours. After drying, the film thickness was 45 μm. The film was cut into circular polymer electrolyte membranes with a diameter of 19 mm in the glove box.

[0056] Example 4

[0057] This embodiment provides a method for preparing a surface salt segregation polymer electrolyte membrane, comprising the following steps:

[0058] (1) 0.5 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and 0.4 g of lithium bis(fluorosulfonyl)imide (LiFSI) were dissolved in 6 mL of anhydrous DMF and stirred at 60 °C for 1 h to dissolve. 0.1 g of LLZTO (Li 6.25 Al 0.25 La3Zr2O 12 , purchased from Ronggu New Material Technology (Shaoxing) Co., Ltd.) nanopowder and 0.65 mL of trifluoromethyl ethylene carbonate (TFEC) solvent, and continued stirring for 3 h until the inorganic nanoparticles were uniformly dispersed in the solution.

[0059] (2) The casting mixture obtained in step (1) was cast into a film in an argon atmosphere glove box, transferred to a vacuum drying oven, and vacuum dried at 65°C for 30 hours. After drying, the film thickness was 43 μm. The film was cut into circular polymer electrolyte membranes with a diameter of 19 mm in the glove box.

[0060] Example 5

[0061] This embodiment provides a method for preparing a surface salt segregation polymer electrolyte membrane, comprising the following steps:

[0062] (1) 0.5 g PVDF-HFP powder and 0.4 g LiFSI were dissolved in 6 mL of anhydrous DMF and stirred at 60 °C for 1 h to dissolve. 0.1 g LLZTO nanopowder and 0.65 mL of triethyl fluorophosphate (FTEP) solvent were added and stirred for 3 h until the inorganic nanoparticles were uniformly dispersed in the solution.

[0063] (2) The cast membrane mixture obtained in step (1) was coated onto a porous polyimide (PI) separator with a porosity of 70% (pore size approximately 2 μm, thickness 10 μm). After drying, the membrane was coated on the other side (coating process was the same as above) and vacuum dried at 65°C for 30 h. After drying, the membrane had a thickness of 30 μm and was cut into circular polymer electrolyte membranes with a diameter of 19 mm in a glove box.

[0064] Comparative Example 1

[0065] This embodiment provides a method for preparing a polymer electrolyte membrane, comprising the following steps:

[0066] (1) Dissolve 0.5 g PVDF powder and 0.352 g NaFSI in 6 mL of anhydrous N,N-dimethylformamide (DMF), stir at 60 °C for 1 h to dissolve, and add 0.1 g Na3Zr2Si2PO 12 Nanopowder was stirred continuously at room temperature for 3 h until the nanoparticles were evenly dispersed in the solution;

[0067] (2) The casting mixture obtained in step (1) was cast into a film in an argon atmosphere glove box, transferred to a vacuum drying oven, and vacuum dried at 65°C for 24 hours. After drying, the film thickness was 40 μm, and the film was cut into circular polymer electrolyte membranes with a diameter of 19 mm in the glove box.

[0068] Time-of-flight secondary ion mass spectrometry test of the surface salt segregation polymer electrolyte membrane obtained in Comparative Example 1 CF3SO2 - The 3D rendering of Figure 3 As shown in the figure, no regular distribution of light and dark colors was observed, and the results showed that NaFSI was not enriched on the surface of the polymer electrolyte membrane obtained in Comparative Example 1.

[0069] Example 6

[0070] This embodiment provides a method for assembling and testing a solid-state battery containing a polymer electrolyte membrane. The specific process steps are as follows:

[0071] 1. The ionic conductivity of the polymer electrolyte was measured by AC impedance of the assembled half-cell. The room temperature ionic conductivity of the surface salt segregation polymer electrolyte prepared in Example 1 was 0.56 mS cm -1 ,like Figure 5 shown.

[0072] 2. Assemble sodium / sodium symmetric batteries, with sodium metal as the positive and negative electrodes and a polymer electrolyte as the separator, in a glove box. The assembled sodium / sodium symmetric battery was tested for current cycling performance at room temperature. The sodium / sodium symmetric battery assembled with the surface salt segregation polymer electrolyte membrane prepared in Example 1 had a high current cycling performance at 0.5 mA cm -2 or 1mA cm -2 The current cycling performance is as follows: Figure 6 and Figure 7 As shown in the figure, the cycling performance remains relatively stable after 700h and 350h, and the polarization voltage is about 0.2V.

[0073] 3. Assemble solid-state sodium battery (sodium iron phosphate pyrophosphate / sodium battery), with sodium iron phosphate pyrophosphate as the positive electrode and sodium metal as the negative electrode. The charge and discharge performance of the assembled solid-state sodium battery was tested at 25°C. The rate performance of the solid-state sodium battery assembled with the surface salt segregation polymer electrolyte prepared in Example 1 is as follows: Figure 8 As shown, at 0.2C, 0.5C, 1C, 2C, 4C, 6C, 8C (1C = 129mA g -1 ) and the specific capacity were 112 mAh g -1 , 105mAh g -1 , 100mAh g -1 , 95mAh g -1 , 90mAh g -1, 73mAh g -1 , 40mAh g -1 .

[0074] The cycle performance of the solid-state sodium battery assembled with the surface salt segregation polymer electrolyte prepared in Example 1 is as follows: Figure 9 As shown, 1C (1C = 129mAg -1 ) discharge capacity is about 103 mAh g -1 , the capacity retention rate after 750 cycles is 97.5%.

[0075] Table 1 Properties of polymer electrolytes prepared in Examples 1-5 and Comparative Example 1 and their electrochemical performance in all-solid-state sodium batteries

[0076] High boiling point solvents Porous support membrane Tensile modulus Room temperature ionic conductivity 1C*500 cycles capacity retention rate Example 1 TFEC none 6.3MPa <![CDATA[5.6×10 -4 S cm -1 ]]> 92.0％ Example 2 TFEC PP 60MPa <![CDATA[6.7×10 -4 S cm -1 ]]> 98.5％ Example 3 FTEP none 10.1MPa <![CDATA[4.2×10 -4 S cm -1 ]]> 88.1％ Example 4 TFEC none 7.6MPa <![CDATA[3.1×10 -4 S cm -1 ]]> 84.5％ Example 5 FTEP PI 100.2MPa <![CDATA[6.2×10 -4 S cm -1 ]]> 96.6％ Comparative Example 1 none none 0.5MPa <![CDATA[1.2×10 -4 S cm -1 ]]> 5.2％

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a surface salt segregation polymer electrolyte, characterized in that: The steps include: S1: adding a mixed solvent consisting of a low-boiling-point, high-polymer-solubility solvent and a high-boiling-point, high-salt-solubility, low-polymer-solubility solvent to a high-molecular-weight skeleton polymer and a solute salt or a high-molecular-weight skeleton polymer, a solute salt, and a filler powder, and uniformly mixing all the components by stirring, homogenizing, or ball milling to obtain a target casting solution; S2: Casting the casting solution obtained in step S1 into a film, or casting, coating or applying it on a porous support membrane; S3: drying the film obtained in step S2 to obtain a polymer electrolyte; In step S1, the difference in boiling point between the low boiling point solvent and the high boiling point solvent is greater than 5°C; the volume ratio of the low boiling point solvent to the high boiling point solvent is (1-100):1; The low boiling point solvent in step S1 includes methanol, ethanol, propanol, N,N-dimethylformamide, butyronitrile, acetone or tetrahydrofuran, and the high boiling point solvent includes propylene carbonate, triethyl fluorophosphate (FTEP), fluoroethylene carbonate (FEC) or trifluoromethylethylene carbonate (TFEC).

2. The preparation method according to claim 1, characterized in that The mass ratio of the high molecular weight skeleton polymer, the solute salt and the filler powder in step S1 is (0.2~20):1:(0~1).

3. The preparation method according to claim 1, characterized in that The high molecular weight backbone polymer in step S1 includes one or a combination of two or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), polyacrylonitrile (PAN) or polymethyl methacrylate (PMMA); The cations in the solute salt include lithium ions (Li + ), sodium ion (Na + ) or potassium ions (K + ), anions include bis(trifluoromethanesulfonyl)imide (TFSI - ), bis(fluorosulfonyl)imide (FSI - ), trifluoromethanesulfonyl (OTf-), perchlorate (ClO4 - ), tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroarsenate (AsF6 - ), nitrate (NO3 - ), bis(oxalatoborate) (BOB - ) or difluorooxalate boric acid (ODFB - ) or a combination of two or more; The filler powder includes one or a combination of inorganic solid electrolytes and metal organic framework compounds (MOFs).

4. The preparation method according to claim 1, characterized in that The difference in boiling point between the low boiling point solvent and the high boiling point solvent in step S1 is ≥ 50°C.

5. The preparation method according to claim 1, characterized in that The solid content of the casting solution in step S1 is 5-90 wt %.

6. The preparation method according to claim 1, characterized in that The porous support membrane has a porosity of 10-98% and is made of polyethylene (PE), polypropylene (PP) or polyimide (PI).

7. The surface salt segregation polymer electrolyte prepared by the preparation method according to any one of claims 1 to 6.

8. The surface salt segregation polymer electrolyte according to claim 7 is used in solid-state batteries and semi-solid-state battery systems.

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