Energy storage lithium battery, sulfur-containing polymer solid electrolyte membrane and preparation method of sulfur-containing polymer solid electrolyte membrane

Abstract

The invention discloses an energy storage lithium battery, a sulfur-containing polymer solid-state electrolyte membrane and a preparation method, and belongs to the technical field of polymer electrolytes.A functional polymer is added into the solid-state electrolyte membrane, the functional polymer is formed by quickly crosslinking polyethylene glycol dimethacrylate (PEGDMA) and diphenyl disulfide (DPDS) through the thermal initiation polymerization effect, and the functional polymer is a sulfur-containing polymer solid-state electrolyte membrane and a preparation method of the sulfur-containing polymer solid-state electrolyte membrane. The sulfur-containing polymer solid electrolyte membrane can simultaneously improve the voltage resistance and the high ion conduction performance of the polymer electrolyte, so that the problems of low room-temperature ion conductivity, high interface impedance, poor mechanical property and high crystallinity of the sulfur-containing polymer solid electrolyte membrane in the prior art are solved; and great gain is provided for battery circulation and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer electrolytes, and in particular relates to an energy storage lithium battery and a sulfur-containing polymer solid electrolyte membrane and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in wireless communications, laptop computers, new energy vehicles and other fields due to their high voltage, sufficient energy density and long cycle life. However, lithium-ion batteries have always faced two major challenges: limited energy density and poor safety, and therefore cannot meet the growing demand for batteries with higher energy density and higher safety. Commercial lithium-ion batteries mainly use liquid electrolytes composed of flammable organic carbonates, which are extremely volatile and flammable. In addition, when liquid electrolytes are used in lithium-ion batteries, the growth of lithium dendrites is particularly prone to occur. As an important component of lithium-ion batteries, the electrolyte has a great influence on the electrochemical performance of lithium-ion batteries.

[0003] Solid-state lithium batteries have attracted considerable attention due to their high safety and excellent high-temperature performance. Solid electrolytes in lithium batteries are classified into two types: inorganic and polymer electrolytes. Compared to inorganic solid electrolytes, polymer electrolytes offer promising prospects for solid-state lithium batteries due to their excellent flexibility, safety, and processability. Therefore, they hold a greater potential for development. Previously, solid polymer electrolytes, represented by polyethylene oxide (PEO), were severely hampered by their low ionic conductivity at room temperature, weak interfacial contact between the electrolyte and the electrode, a narrow electrochemical window, and susceptibility to oxidation at high charge potentials, severely hindering their widespread application in solid-state lithium batteries. Researchers have also developed nitrile-based, siloxane-based, carbonate-based, and vinylidene fluoride-based polymer electrolytes. However, due to the homogeneous nature of the polymer backbone, sulfur-containing polymer solid electrolyte membranes still suffer from low room-temperature ionic conductivity, high interfacial impedance, poor mechanical properties, and high crystallinity. Summary of the Invention

[0004] The present invention provides an energy storage lithium battery and a sulfur-containing polymer solid electrolyte membrane and a preparation method. A functional polymer is added to the solid electrolyte membrane. The functional polymer is synthesized by rapid cross-linking of polyethylene glycol dimethacrylate (PEGDMA) and diphenyl disulfide (DPDS) through thermal polymerization. This can solve the problems of low room temperature ionic conductivity, high interfacial impedance, poor mechanical properties and high crystallinity of sulfur-containing polymer solid electrolyte membranes in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solution: a sulfur-containing polymer solid electrolyte membrane, comprising a functional polymer, the general structural formula of the functional polymer is as follows:

[0006] Wherein, n and m represent the degree of polymerization or the number of repeating units.

[0007] Furthermore, the functional polymer is obtained by thermally initiating polymerization of polyethylene glycol dimethacrylate and diphenyl disulfide.

[0008] Furthermore, the mass ratio of the polyethylene glycol dimethacrylate to diphenyl disulfide is 1:(1-10).

[0009] Furthermore, it also includes lithium salt, and the functional polymer solution and the lithium salt are mixed, spread out, and dried to obtain a sulfur-containing polymer solid electrolyte membrane.

[0010] Furthermore, the added amount of the lithium salt is 20% to 80% of the mass of the functional polymer.

[0011] The present invention provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising: Polyethylene glycol dimethacrylate PEGDMA and diphenyl disulfide DPDS are mixed uniformly according to a preset ratio, and cooled to room temperature after the reaction to obtain a polymer solid; dissolving the obtained polymer solid in a solvent, and adding a lithium salt to mix, to obtain a precursor solution; The precursor solution was spread and dried to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA. x -DPDS y , where x and y are the mass ratios of the two substances.

[0012] Furthermore, polyethylene glycol dimethacrylate and diphenyl disulfide are stirred and reacted at 60° C. to 130° C. for 10 min to 120 min, and then cooled to room temperature to obtain a polymer solid.

[0013] Furthermore, the obtained polymer solid is dissolved in N,N-dimethylamide, and lithium bis(trifluoromethanesulfonyl)imide is added and stirred at room temperature for 12 h to 24 h to obtain a precursor solution.

[0014] Furthermore, the precursor solution is cast on the surface of a PTFE mold to spread the precursor solution evenly, and dried at 60° C. to 130° C. under a vacuum environment to obtain a sulfur-containing polymer solid electrolyte membrane.

[0015] The present invention also provides an energy storage lithium battery, wherein the electrolyte membrane of the energy storage lithium battery adopts the above-mentioned sulfur-containing polymer solid electrolyte membrane.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention discloses a sulfur-containing polymer solid electrolyte membrane, which introduces a functional polymer synthesized by rapid cross-linking of PEGDMA and DPDS through thermal polymerization. This functional polymer cleverly combines the characteristics of the two raw materials. The ether oxygen bond (-O-) of PEGDMA has excellent lithium salt dissociation ability, which can be used for lithium ions (Li + ) constructs fast migration channels, greatly improving the transmission efficiency of lithium ions. The disulfide bonds (-SS-) of DPDS effectively reduce the crystallinity of the polymer, making the conduction of ions in the membrane smoother and significantly improving the ionic conductivity. At the same time, the sulfur-containing structure plays an important role at the electrode / electrolyte interface, effectively suppressing potential polarization and side reactions, and enhancing electrochemical stability. In addition, the benzene rings in DPDS give the electrolyte membrane high mechanical rigidity, which can effectively prevent lithium dendrites from penetrating and ensure the safe operation of the battery. The three-dimensional cross-linked network structure of the electrolyte membrane ensures the uniformity of film formation and provides strong support for the long-term cycling performance of the battery. In practical applications, the prepared sulfur-containing polymer solid electrolyte membrane has a moderate thickness (25μm~35μm), low impedance at room temperature (only 1200Ω), and an electrochemical window of 4.2V. The lithium deposition / stripping curve also demonstrates its good interfacial compatibility with the electrode, which can effectively suppress the growth of lithium dendrites and exhibit excellent cycling stability.

[0017] The preparation method of the present invention has the characteristics of easy preparation and simple molding process. Through thermally initiated polymerization, PEGDMA and DPDS are rapidly cross-linked to synthesize functional polymers, thereby preparing sulfur-containing polymer solid electrolyte membranes. This preparation method avoids complex and tedious process flows, reduces production costs, and improves production efficiency. During the preparation process, the reaction conditions can be precisely controlled to ensure that the structure and performance of the functional polymer meet the expected requirements. Through a simple molding process, an electrolyte membrane with uniform thickness and stable performance can be prepared to meet the needs of different lithium batteries. This preparation method not only provides new ideas for the research and development of solid electrolyte membranes, but also brings new opportunities for the development of the lithium battery industry.

[0018] The sulfur-containing polymer solid electrolyte membrane of the present invention is applied to lithium batteries. In terms of interface stability, the assembled lithium battery has an initial discharge capacity of 146 mAh·g at a 0.5C rate. -1, indicating that the electrolyte membrane and the electrode have good interfacial compatibility, which can effectively reduce the interfacial impedance and improve the performance of the battery. At the same time, the electrolyte membrane can effectively inhibit the growth of lithium dendrites, greatly improving the safety of the battery and reducing safety hazards such as short circuits and fires caused by lithium dendrites piercing the diaphragm. In addition, its excellent electrochemical stability and cycle stability give the battery a longer service life and reduce the cost of battery use. Moreover, the application of this solid electrolyte membrane provides a new path for high-safety, long-life semi-solid-state batteries, which is expected to promote the wider application of lithium battery technology in electric vehicles, energy storage and other fields, and bring new changes to energy storage and utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Impedance spectrum of a battery equipped with the sulfur-containing polymer solid electrolyte membrane prepared in Example 1 of the present invention; Figure 2 Impedance spectrum of a battery equipped with the sulfur-containing polymer solid electrolyte membrane prepared in Example 2 of the present invention; Figure 3 Impedance spectrum of a battery equipped with the sulfur-containing polymer solid electrolyte membrane prepared in Example 3 of the present invention; Figure 4 This is the electrochemical window diagram of the sulfur-containing polymer solid electrolyte membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The present invention provides a sulfur-containing polymer solid electrolyte membrane, wherein a functional polymer is added. The functional polymer is synthesized by rapid cross-linking of polyethylene glycol dimethacrylate (PEGDMA) and diphenyl disulfide (DPDS) through thermal polymerization. The general structural formula of the polymer is as follows:

[0023] Where n and m represent the degree of polymerization or the number of repeating units. It represents the average number of times the monomer units (or structural units) that make up the polymer chain are repeatedly connected.

[0024] The present invention uses thermally initiated polymerization to rapidly crosslink polyethylene glycol dimethacrylate PEGDMA and diphenyl disulfide DPDS to synthesize a PEGDMA-DPDS polymer. The PEGDMA-DPDS polymer is used to prepare a solid electrolyte that can achieve high ionic conductivity at room temperature, overcomes the disadvantage of low room temperature ionic conductivity in the prior art, and expands the application range of the electrolyte membrane in low temperature environments. - Dissociate lithium salts and reduce Li + Migration energy barrier; -SS- bond reduces crystallinity, and its sulfur atom lone pair electrons directly promote Li + The jumping structure design significantly improves the ion transmission efficiency and solves the problem of low ion transmission efficiency of polymer solid electrolytes in the existing technology; the sulfur-containing component design uses the lone pair electrons of sulfur atoms to directly promote the Li + The invention relates to a novel polymer electrolyte with a simple structure and a simple structure. The invention relates to a ... structure.

[0025] The present invention also provides a method for preparing the above-mentioned sulfur-containing polymer solid electrolyte membrane, comprising: Step 1: polyethylene glycol dimethacrylate PEGDMA and diphenyl disulfide DPDS are uniformly mixed in a mass ratio of 1:1 to 1:10, magnetically stirred in an oil bath at a temperature of 60°C to 130°C for 10 minutes to 120 minutes, and cooled to room temperature after the reaction to obtain a polymer solid; Step 2: dissolving the obtained polymer solid in N,N-dimethylformamide (DMF), adding lithium bis(trifluoromethanesulfonyl)imide (LITFSI), and magnetically stirring at room temperature for 12 h to 24 h to obtain a precursor solution; Among them, the addition amount of lithium bis(trifluoromethanesulfonyl)imide (LITFSI) is 20%~80% of the sum of the mass of polyethylene glycol dimethacrylate PEGDMA and diphenyl disulfide DPDS.

[0026] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, and dry it in a vacuum oven at 60°C~130°C to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA. x -DPDS y , where x and y are the mass ratios of the two substances.

[0027] Step 4: Prepared sulfur-containing polymer solid electrolyte membrane PEGDMA x -DPDS y Store in an argon environment with water <0.1ppm and oxygen <0.1ppm.

[0028] In the above preparation method, the mass ratio of PEGDMA and DPDS is 1:1~1:10, and the addition amount of LITFSI is 20%~80% of the sum of the mass of PEGDMA and DPDS. The selection of these parameter ranges can achieve the optimal ratio of each component and further optimize the performance of the electrolyte; in the above preparation method, the oil bath temperature is 60℃~130℃, the magnetic stirring time is 10min~120min, the precursor solution is magnetically stirred in DMF at room temperature for 12h~24h, and the vacuum oven drying temperature is 60℃~130℃. The precise control of these parameters helps to ensure the uniformity and stability of the sulfur-containing polymer solid electrolyte membrane.

[0029] The solid electrolyte membrane obtained by the present invention is extremely easy to prepare and has a simple molding process. The prepared sulfur-containing polymer solid electrolyte membrane has a thickness of 25μm~35μm, an impedance of only 1200Ω at room temperature, and an electrochemical window of 4.2V. The lithium deposition / stripping curve proves that the interface compatibility between the electrolyte membrane and the electrode is good, which can effectively inhibit the growth of lithium dendrites and show excellent cycle stability. It was applied to the LFP-Li solid-state battery. In terms of interface stability, the assembled lithium battery measured the battery's first discharge capacity at a rate of 0.5C to be 146 mAh·g -1 , providing a new path for high-safety, long-life semi-solid-state batteries.

[0030] In the following examples, unless otherwise specified, all materials used can be obtained through common channels; and the testing methods adopted are conventional methods in the art.

[0031] Example 1 This embodiment provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising the following steps: Step 1: PEGDMA and DPDS were mixed evenly in a mass ratio of 1:5, magnetically stirred in an oil bath at a temperature of 130°C for 120 minutes, and cooled to room temperature after the reaction to obtain a polymer solid.

[0032] Step 2: Dissolve the resulting polymer solid in DMF and add LITFSI, followed by magnetic stirring at room temperature for 24 hours to obtain a precursor solution. The amount of LITFSI added is 40% of the combined weight of PEGDMA and DPDS.

[0033] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, ensure a vacuum atmosphere in the oven, and dry it in a vacuum oven at 130° C. for 12 h to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS5.

[0034] Step 4: The prepared sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS5 is stored in an argon environment, wherein the water content in the argon environment is <0.1 ppm and the oxygen content is <0.1 ppm.

[0035] Example 2 In this example, sulfur-containing polymer solid electrolyte membrane (PEGDMA1-DPDS 2.5 ) are as follows: basically the same as Example 1, except that the mass ratio of PEGDMA to DPDS in step 1 is 1:2.5.

[0036] Example 3 The specific steps for preparing the sulfur-containing polymer solid electrolyte membrane (PEGDMA1-DPDS1) in this example are as follows: basically the same as in Example 1, except that the mass ratio of PEGDMA to DPDS in step 1 is 1:1.

[0037] Example 4: This embodiment provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising the following steps: Step 1: PEGDMA and DPDS were mixed in a mass ratio of 1:5, and magnetically stirred in an oil bath at 100°C for 30 minutes. PEGDMA and DPDS were then adjusted in a mass ratio and cooled to room temperature to obtain a polymer solid.

[0038] Step 2: Dissolve the resulting polymer solid in DMF, add LITFSI, and magnetically stir at room temperature for 18 hours to obtain a precursor solution. The amount of LITFSI added is 50% of the combined weight of PEGDMA and DPDS.

[0039] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, ensure a vacuum atmosphere in the oven, and dry it in a vacuum oven at 80° C. for 12 h to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS5.

[0040] Step 4: The prepared sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS5 is stored in an argon environment, wherein the water content in the argon environment is <0.1 ppm and the oxygen content is <0.1 ppm.

[0041] Example 5: This embodiment provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising the following steps: Step 1: PEGDMA and DPDS were mixed uniformly in a mass ratio of 1:7, magnetically stirred in an oil bath at 100°C for 45 minutes, and cooled to room temperature after the reaction to obtain a polymer solid.

[0042] Step 2: Dissolve the resulting polymer solid in DMF, add LITFSI, and magnetically stir at room temperature for 20 hours to obtain a precursor solution. The amount of LITFSI added is 30% of the combined weight of PEGDMA and DPDS.

[0043] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, ensure a vacuum atmosphere in the oven, and dry it in a vacuum oven at 100° C. for 12 h to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS7.

[0044] Step 4: The prepared sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS7 is stored in an argon environment, wherein the water content in the argon environment is <0.1 ppm and the oxygen content is <0.1 ppm.

[0045] Example 6: This embodiment provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising the following steps: Step 1: PEGDMA and DPDS were mixed uniformly in a mass ratio of 1:9, magnetically stirred in an oil bath at 120°C for 15 minutes, and cooled to room temperature after the reaction to obtain a polymer solid.

[0046] Step 2: Dissolve the resulting polymer solid in DMF, add LITFSI, and magnetically stir at room temperature for 12 hours to obtain a precursor solution. The amount of LITFSI added is 60% of the combined mass of PEGDMA and DPDS.

[0047] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, ensure a vacuum atmosphere in the oven, and dry it in a vacuum oven at 90° C. for 12 h to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS9.

[0048] Step 4: The prepared sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS9 is stored in an argon environment, wherein the water content in the argon environment is <0.1 ppm and the oxygen content is <0.1 ppm.

[0049] Example 7: This embodiment provides a method for preparing a sulfur-containing polymer solid electrolyte membrane, comprising the following steps: Step 1: PEGDMA and DPDS were mixed uniformly in a mass ratio of 1:10, magnetically stirred in an oil bath at 110° C. for 20 min, and cooled to room temperature after the reaction to obtain a polymer solid.

[0050] Step 2: Dissolve the resulting polymer solid in DMF and add LITFSI. Magnetic stirring is performed at room temperature for 16 hours to obtain a precursor solution. The amount of LITFSI added is 50% of the combined weight of PEGDMA and DPDS.

[0051] Step 3: Cast the precursor solution on the surface of the PTFE mold to spread the precursor solution evenly, ensure the vacuum atmosphere in the oven, and dry it in a vacuum oven at 70°C for 18 hours to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS. 10 .

[0052] Step 4: Prepared sulfur-containing polymer solid electrolyte membrane PEGDMA1-DPDS 10 Store in an argon environment with water <0.1ppm and oxygen <0.1ppm.

[0053] Comparative Example 1 The specific steps for preparing the polymer solid electrolyte membrane in this comparative example are as follows: 10.00 g of polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP and 4.00 g of lithium bistrifluoromethanesulfonyl imide LiTFSI were dissolved in 50 ml of N,N-dimethylformamide DMF solution, the resulting solution was poured on the surface of a glass plate, and vacuum dried at 60°C for 24 hours to obtain a polymer solid electrolyte membrane.

[0054] The mechanical properties of the solid electrolyte membranes prepared in Examples 1 to 7 and Comparative Example 1 were tested, and the data are shown in Table 1: Table 1 is the mechanical properties test data

[0055] As shown in Table 1, the ultra-high flexibility (elongation at break of 300% to 500%) of the electrolyte membrane of the present invention is due to the dynamic reversible properties of the -SS- bond in DPDS: during the stretching process, the -SS- bond breaks / recombines as a "sacrificial bond" to absorb energy, making Example 2 (PEGDMA1-DPDS 2.5) The elongation at break reaches 500%; at the same time, the benzene ring structure of DPDS provides moderate rigid support to avoid strength collapse caused by high flexibility (tensile strength of 1.5MPa in Example 1). Compared with the rigidity defects of the traditional material (Comparative Example 1) (elongation at break is only 15%, Young's modulus is 110.5MPa), the present invention achieves "rigidity and flexibility" by regulating the DPDS ratio: Example 3 (PEGDMA1-DPDS1) has an increased Young's modulus (8.5MPa) due to the excessive proportion of benzene rings, but it is still significantly lower than Comparative Example 1; Example 2 has the optimal cross-linking density, achieving the highest elongation at break (500%) while maintaining a tensile strength of 0.8MPa; Example 7 shows that as the DPDS content increases, the increase in the DPDS ratio significantly increases the disulfide bond cross-linking density, which dominates the enhancement of material rigidity, the increase in Young's modulus, the decrease in ductility corresponding to the decrease in elongation at break, and the increase in tensile strength corresponding to the increase in strength. At the same time, the π-π stacking effect of the benzene rings at high DPDS content, synergistically with crosslinking, further strengthens the network's rigidity and brittleness, making the material harder and more brittle in the highly crosslinked regions, providing a key mechanical barrier for suppressing lithium dendrites. Data confirm that the -SS- bond of DPDS is the core design element for balancing ultraflexibility and structural integrity.

[0056] Example 8 like Figure 4 As shown, Example 1 (PEGDMA1-DPDS5) exhibits an excellent electrochemical window of 4.2 V, which is due to its moderate cross-linking network: it provides sufficient disulfide bond stability and chain segment regularity to inhibit electrolyte decomposition, and avoids side reactions that may be caused by excessive aggregation of benzene rings or overly dense cross-linking under high DPDS, thereby maintaining good electrochemical stability.

[0057] The sulfur-containing polymer solid electrolyte membrane prepared in Example 1 was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) into a 2025 model button battery, and the performance test was carried out: the conductivity at room temperature was measured to be 3.3×10 -4 S / cm -1 To test the application of sulfur-containing polymer solid electrolyte membrane in all-solid-state lithium batteries, it was assembled into LiFePO4 / PEGDMA1-DPDS5 / Li battery and tested the charge and discharge cycle at 60°C. The first discharge capacity of the battery was measured to be 150 mAh·g at a rate of 0.1C. -1 .

[0058] The polymer solid electrolyte membrane prepared in Comparative Example 1 was assembled into a LiFePO4 / PVDF-HFP / Li battery and the charge-discharge cycle performance was tested at 60°C. The conductivity of the polymer solid electrolyte membrane at room temperature was 3.96×10 -5 S / cm -1The first discharge capacity of the battery was measured at a rate of 0.5C to be 102 mAh·g -1 , the impedance of the LiFePO4 / PVDF-HFP / Li battery is 12400Ω after 100 cycles.

[0059] Example 9 The sulfur-containing polymer solid electrolyte membranes prepared in Examples 2 and 3 were used to prepare an all-solid-state lithium battery using the method of Example 8. The impedance diagram of the battery after 100 cycles was as follows: Figures 1-3 As shown, it can be seen that the excellent performance of Example 1 (PEGDMA1-DPDS5, impedance 1200Ω) is due to the synergistic effect of the high DPDS ratio (1:5). The dynamic -SS- bond greatly increases the proportion of amorphous regions (>80%), constructing a continuous Li⁺ channel; at the same time, the ether oxygen bond (-O-) forms a double-site coordination with the lone pair of electrons of the sulfur atom, synergistically reducing the activation energy of Li⁺ migration and increasing the migration number (>0.45); the sulfur-containing component further forms a uniform SEI layer at the interface, significantly reducing the interface impedance. In contrast, Example 2 (PEGDMA1-DPDS 2.5 Example 3 (PEGDMA1-DPDS1, impedance 4200Ω) exhibits a structural defect: the low DPDS content (1:1) eliminates the conductive contribution of the -SS- bonds, while the stacking of benzene rings forms a barrier layer. Furthermore, the high crystallinity (40%) forces Li⁺ to migrate in a circumventive manner. In summary, the impedance gradient clearly reveals that the dynamic crosslinking and two-site coordination of the -SS- bonds are the key to overcoming the conductive bottleneck.

[0060] In summary, the reason why the conductivity of the polymer solid electrolyte membrane prepared in Comparative Example 1 is low is that PVDF-HFP has a high crystallinity, which inhibits the Li + Migration of electrolytes can lead to low ionic conductivity. However, this invention simultaneously addresses three bottlenecks in solid-state electrolytes by regulating the DPDS ratio. The high DPDS content (1:5) leverages -SS- bonds in synergistic ether oxygen bonds to reduce impedance to 1200Ω, rivaling the conductivity of liquid electrolytes. The sulfur-containing polymer forms a stable SEI layer in situ at the electrode interface, significantly suppressing potential polarization and side reactions (such as LiTFSI decomposition), thereby improving cycle life. The dynamic cross-linking network imparts a 300%-500% elongation at break to the membrane, minimizing the risk of lithium dendrite penetration. This synergistic combination of high ionic conductivity, interfacial stability, and mechanical flexibility provides a solution for the development of high-energy-density, high-safety solid-state lithium batteries.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A sulfur-containing polymer solid electrolyte membrane, characterized in that: It includes a functional polymer, the general structural formula of which is shown below: Wherein, n and m represent the degree of polymerization or the number of repeating units.

2. The sulfur-containing polymer solid electrolyte membrane according to claim 1, characterized in that: The functional polymer is obtained by thermally initiating polymerization of polyethylene glycol dimethacrylate and diphenyl disulfide.

3. The sulfur-containing polymer solid electrolyte membrane according to claim 2, characterized in that: The mass ratio of the polyethylene glycol dimethacrylate to diphenyl disulfide is 1:(1-10).

4. The sulfur-containing polymer solid electrolyte membrane according to claim 1, characterized in that: It also includes lithium salt. The functional polymer solution and the lithium salt are mixed, spread out, and dried to obtain a sulfur-containing polymer solid electrolyte membrane.

5. The sulfur-containing polymer solid electrolyte membrane according to claim 4, characterized in that: The added amount of the lithium salt is 20% to 80% of the mass of the functional polymer.

6. The method for preparing a sulfur-containing polymer solid electrolyte membrane according to any one of claims 1 to 5, characterized in that: include: Polyethylene glycol dimethacrylate PEGDMA and diphenyl disulfide DPDS are mixed uniformly according to a preset ratio, and cooled to room temperature after the reaction to obtain a polymer solid; dissolving the obtained polymer solid in a solvent, and adding a lithium salt to mix, to obtain a precursor solution; The precursor solution was spread and dried to obtain the sulfur-containing polymer solid electrolyte membrane PEGDMA. x -DPDS y , where x and y are the mass ratios of the two substances.

7. The method for preparing a sulfur-containing polymer solid electrolyte membrane according to claim 6, characterized in that: Polyethylene glycol dimethacrylate and diphenyl disulfide are stirred and reacted at 60° C. to 130° C. for 10 min to 120 min, and then cooled to room temperature to obtain a polymer solid.

8. The method for preparing a sulfur-containing polymer solid electrolyte membrane according to claim 6, characterized in that: The obtained polymer solid is dissolved in N,N-dimethylamide, and lithium bis(trifluoromethanesulfonyl)imide is added and stirred at room temperature for 12 h to 24 h to obtain a precursor solution.

9. The method for preparing a sulfur-containing polymer solid electrolyte membrane according to claim 6, characterized in that: The precursor solution is cast on the surface of a PTFE mold to spread the precursor solution evenly, and is dried at 60° C. to 130° C. in a vacuum environment to obtain a sulfur-containing polymer solid electrolyte membrane.

10. An energy storage lithium battery, characterized in that: The electrolyte membrane of the energy storage lithium battery adopts a sulfur-containing polymer solid electrolyte membrane according to any one of claims 1 to 5.

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