Sulfur-containing solid-state polymer electrolyte membrane for energy storage battery and preparation method and application thereof

Abstract

This invention discloses a sulfur-containing solid polymer electrolyte membrane for energy storage batteries, its preparation method, and its application, belonging to the field of polymer electrolyte technology. The preparation method of the sulfur-containing solid polymer electrolyte membrane includes uniformly mixing dimethyl tetrasulfide and dithiobenzoic acid, and obtaining a solid polymer through a polycondensation reaction; dissolving the solid polymer in N,N-dimethylamide to obtain a mixed solution; adding lithium bis(trifluoromethanesulfonyl)imide to the mixed solution and mixing uniformly to obtain a precursor solution; electrospinning the precursor solution to form a fiber membrane, and then vacuum drying to obtain the sulfur-containing solid polymer electrolyte membrane. The sulfur-containing solid polymer electrolyte membrane provided by this invention achieves a unified synergistic effect of improved ionic conductivity, enhanced interface stability, and optimized mechanical properties through a four-dimensional synergistic conduction mechanism. Lithium metal batteries equipped with this electrolyte membrane have comprehensive advantages such as high safety, long cycle life, and excellent electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of polymer electrolyte technology, specifically relating to a sulfur-containing solid polymer electrolyte membrane for energy storage batteries, its preparation method, and its application. Background Technology

[0002] Lithium metal batteries have shown great potential as a next-generation high-energy-density energy storage system. However, the commonly used organic liquid electrolytes present significant safety issues, such as high flammability and explosiveness. More critically, organic liquid electrolytes are prone to initiating severe corrosion reactions at the lithium metal anode interface and are difficult to effectively suppress the random growth of lithium dendrites. These problems constitute the main obstacles to the commercial application of lithium metal batteries.

[0003] Solid-state electrolytes, as core components of high-energy-density lithium-ion batteries, have recently developed into two main systems: inorganic and polymeric. Compared to inorganic systems, polymeric solid-state electrolytes are considered a more promising choice for practical applications due to their superior mechanical flexibility, safety, and processability. However, traditional polymeric electrolytes, represented by polyethylene oxide (PEO), face severe challenges: low lithium-ion mobility at room temperature, high solid-solid interface contact impedance, narrow electrochemical stability window, and easy oxidation and decomposition under high-voltage charging conditions. These problems severely limit their performance in solid-state batteries. Although subsequent developments of novel polymer systems such as nitrile-based, siloxane-based, and polyvinylidene fluoride have made breakthroughs in single performance dimensions, they still struggle to simultaneously meet the multiple requirements of high ionic conductivity, excellent mechanical strength, and a wide electrochemical window.

[0004] Against this backdrop, the discovery of sulfur-containing polymer electrolytes (Poly(organopolysulfide)) has provided new insights for technological breakthroughs. The densely distributed lone pairs of sulfur atoms in their molecular chains can form high-density lithium-ion coordination sites, constructing a unique "solvation" transport network; sulfur ions (S... 2- The lower electronegativity further weakens the binding effect on lithium ions, reducing the activation energy for ion migration and thus achieving a significant improvement in ionic conductivity and cycle stability. Furthermore, -(SS) n The introduction of flexible segments not only improves the electrode-electrolyte interface contact and compatibility, but also effectively suppresses lithium dendrite growth and extends battery life.

[0005] Despite the significant advantages of sulfur-containing polymers in terms of ion conduction and interfacial compatibility, existing solid-state polymer electrolyte systems still face fundamental challenges: First, the ionic conductivity at room temperature is generally low, making it difficult to meet the requirements of fast charging; second, insufficient solid-solid interface contact leads to persistently high interfacial impedance; and third, the problem of interface stability degradation caused by volume deformation during long-term cycling has not yet been solved. These technical bottlenecks severely restrict the practical application of solid-state batteries. Summary of the Invention

[0006] To overcome the problems of low ionic conductivity, high interfacial impedance, and poor interfacial stability in existing solid polymer electrolytes, this invention provides a sulfur-containing solid polymer electrolyte membrane for energy storage batteries, its preparation method, and its application, thereby achieving high safety, long lifespan, and high energy density solid-state battery integration.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] In a first aspect, the present invention provides a sulfur-containing solid polymer electrolyte membrane, which is prepared by hot melting, spinning and evaporation of a sulfur-containing solid polymer, wherein the general structural formula of the sulfur-containing solid polymer is:

[0009]

[0010] In the formula, n is the degree of aggregation, and 5000 < n < 50000.

[0011] A further improvement of the present invention is that the thickness of the sulfur-containing solid polymer electrolyte membrane is 70µm±5µm.

[0012] Secondly, the present invention also provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, comprising the following steps:

[0013] Dimethyl tetrasulfide and dithiodibenzoic acid are mixed and polycondensed to obtain a solid polymer.

[0014] The solid polymer was dissolved in N,N-dimethylamide to obtain a mixed solution. Lithium bis(trifluoromethanesulfonyl)imide was added to the mixed solution and mixed evenly to obtain a precursor solution.

[0015] The precursor solution was electrospun into a fiber membrane, which was then vacuum dried to obtain a sulfur-containing solid polymer electrolyte membrane.

[0016] A further improvement of the present invention is that the mass ratio of the dimethyltetrasulfide to dithiodibenzoic acid is 1:(1~10).

[0017] A further improvement of the present invention is that the polycondensation reaction is carried out in an oil bath environment at a temperature of 100~180℃ for a reaction time of 30~120min, and after the reaction is completed, it is cooled to room temperature to obtain a solid polymer.

[0018] A further improvement of the present invention is that the amount of lithium bis(trifluoromethanesulfonyl)imide added is 20% to 80% of the total mass of dimethyl tetrasulfide and dithiodibenzoic acid.

[0019] A further improvement of the present invention is that lithium bis(trifluoromethanesulfonyl)imide is added to the mixed solution and magnetically stirred at a temperature of 25~60℃ for 12~48h until the mixture is homogeneous and a precursor solution is obtained.

[0020] A further improvement of the present invention is that, during the electrospinning process:

[0021] The needle has an inner diameter of 0.3~0.8mm, a voltage of 5~20kV, a solution flow rate of 0.5~2ml / h, a distance of 12~18cm between the needle and the receiving plate, and a spinning time of 1~3h.

[0022] A further improvement of the present invention is that the vacuum drying temperature is 25~130℃ and the time is 12~24h.

[0023] Thirdly, the present invention also provides an application of a sulfur-containing solid polymer electrolyte membrane used in lithium-ion batteries.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention provides a sulfur-containing solid polymer electrolyte membrane that achieves a unified synergistic effect of improved ionic conductivity, enhanced interfacial stability, and optimized mechanical properties through a four-dimensional synergistic conduction mechanism of "sulfur chain conduction-carboxyl chelation-hydrogen bond anchoring-dynamic repair". Specifically, the lone pair electrons of the sulfur atom act as Lewis base sites and interact with Li... + The formation of weakly coordinated bonds, combined with a flexible sulfur chain with a low rotational barrier of SS bonds, enables Li to achieve Li through local conformational changes. + The "relay-style" transport significantly reduces the activation energy for ion migration; simultaneously, the C=O group on the benzene ring reacts with Li... + Strong electrostatic interactions are generated, forming stable Li + The O=C coordination site, together with the lithium salt anion, forms a highly efficient ion conduction network, significantly improving the ionic conductivity and electrochemical performance of the electrolyte membrane. The OH group in the carboxylic acid (-COOH) reacts with lithium salt anions (such as TFSI...) - The formation of a hydrogen bond network effectively anchors anions and inhibits their migration, significantly improving the efficiency of Li. +The migration number also hinders the oxidative decomposition of anions, thereby optimizing ion transport efficiency and endowing the material with excellent cycle stability. The dynamic reversible nature of the flexible SS bonds enables the material to have self-healing capabilities, which can repair solid electrolyte interphase (SEI) cracks generated during cycling in real time, avoiding the risk of short circuits caused by lithium dendrites piercing the separator; at the same time, the hydrogen bonds of the -COOH groups form a dynamic physical cross-linking network at the interface, synergistically inhibiting crack propagation and significantly improving the compatibility and long-term structural integrity of the negative electrode interface. In addition, the rigid polymer skeleton formed by the stacked benzene rings endows the electrolyte membrane with high mechanical strength and tensile properties, which not only ensures the process feasibility of battery assembly, but also provides mechanical support for the electrode interface, ultimately achieving a balance of high safety, long cycle life and high energy density, providing key technical support for the practical breakthrough of solid-state lithium batteries.

[0026] This invention also provides a method for preparing a sulfur-containing solid polymer electrolyte membrane. First, dimethyl tetrasulfide and dithiobenzoic acid are directly mixed, and through a condensation reaction, they form a polymer skeleton with both sulfur chain conduction network and hydrogen bond anchoring capabilities. This directly constructs a "sulfur chain-carboxyl group" synergistic conduction structure at the molecular design level, laying the foundation for subsequent ion transport and interface stability. Second, N,N-dimethylamide is selected as a solvent. Its high polarity can fully dissolve the polymer and uniformly disperse the lithium salt, ensuring molecular-level mixing of the lithium salt and polymer matrix in the precursor solution, forming homogeneous ion transport channels. Simultaneously, the low boiling point of N,N-dimethylamide facilitates rapid solvent removal during vacuum drying, avoiding the impact of residues on electrochemical performance. Finally, the precursor solution is processed through electrospinning and vacuum drying to obtain a sulfur-containing solid polymer electrolyte membrane. This allows for precise control of the electrolyte membrane thickness and the formation of a dense, non-porous structure. This ensures high mechanical strength of the electrolyte membrane and, through the dynamic repair capability of the sulfur chains and the physical cross-linking effect of carboxylic acid hydrogen bonds, achieves real-time repair of interfacial cracks, significantly improving the cycle stability of lithium metal batteries. This preparation method achieves precise control of chemical structure, optimization of interfacial ion channels, preservation of dynamic functional groups, and enhancement of mechanical properties through three core operations, which significantly reduces manufacturing costs and is suitable for large-scale production, providing core process support for the industrialization of solid-state batteries. Attached Figure Description

[0027] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components of the invention.

[0028] Figure 1 The XRD pattern of the sulfur-containing solid polymer electrolyte membrane prepared in Example 2 of this invention;

[0029] Figure 2Impedance test diagrams of the polymer electrolyte membranes prepared in Examples 1-3 and Comparative Example 1 of this invention;

[0030] Figure 3(a) is a SEM image of the sulfur-containing solid polymer electrolyte membrane prepared in Example 2 of the present invention;

[0031] Figure 3(b) is a SEM image of the polymer electrolyte membrane prepared in Comparative Example 1 of the present invention;

[0032] Figure 4 The rate performance of the polymer electrolyte membranes prepared in Example 1 and Comparative Example 1 of this invention at 25°C is shown. Detailed Implementation

[0033] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0035] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0037] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0038] This invention provides a sulfur-containing solid polymer electrolyte membrane, prepared by hot melting, spinning, and evaporation of a sulfur-containing solid polymer, wherein the general structural formula of the sulfur-containing solid polymer is:

[0039]

[0040] In the formula, n is the degree of aggregation, and 5000 < n < 50000.

[0041] The thickness of the sulfur-containing solid polymer electrolyte membrane is 70µm±5µm.

[0042] The sulfur-containing solid polymer electrolyte membrane of this invention integrates the dual functions of traditional liquid electrolytes and separator components through its unique solid-state ion conduction properties and physical structure design. Specifically, its solid polymer matrix not only undertakes the core function of ion transport, but its dense and robust physical structure also simultaneously replaces the physical isolation function of the separator. This innovative structure-function integrated design breaks through the inherent limitations of traditional batteries, bringing about a leap in inherent safety, huge potential for energy density improvement, long-life cycle assurance, and adaptability to extreme operating conditions, laying the technological foundation for a new generation of high-safety, high-energy-density, and long-life solid-state batteries.

[0043] This invention also provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, comprising the following steps:

[0044] Dimethyl tetrasulfide (DMTS) and 4,4'-Dithiobisbenzoic acid (DTBA) were mixed evenly and then subjected to a polycondensation reaction to obtain a solid polymer.

[0045] The solid polymer was dissolved in N,N-dimethylformamide (DMF) to obtain a mixed solution. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to the mixed solution and mixed evenly to obtain a precursor solution.

[0046] The precursor solution was electrospun into a fiber membrane, which was then vacuum dried to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS). x -DTBA y ), where x and y represent the mass ratio of dimethyl tetrasulfide and dithiodibenzoic acid, i.e., x=1, 1≤y≤10.

[0047] In some embodiments, the mass ratio of dimethyltetrasulfide to dithiobenzoic acid is 1:(1~10).

[0048] In some embodiments, the polycondensation reaction is carried out in an oil bath at a temperature of 100-180°C for 30-120 minutes, and after the reaction is completed, the mixture is cooled to room temperature to obtain a solid polymer.

[0049] In some embodiments, the amount of lithium bis(trifluoromethanesulfonyl)imide added is 20% to 80% of the total mass of dimethyl tetrasulfide and dithiodibenzoic acid.

[0050] In some embodiments, lithium bis(trifluoromethanesulfonyl)imide is added to the mixed solution and magnetically stirred at a temperature of 25-60°C for 12-48 hours until the mixture is homogeneous and a precursor solution is obtained.

[0051] In some embodiments, the specific method for electrospinning the precursor solution to form a fiber membrane is as follows:

[0052] The precursor solution is loaded into a syringe, and after the air bubbles are expelled, the needle is installed. The high-voltage power supply is turned on, and the voltage is gradually increased until a stable fiber jet is formed at the needle. The injection pump is started to push the precursor solution, and a continuous polymer jet is formed under the action of the electric field. The polymer jet is directionally sprayed onto the receiving plate, and the spinning time is controlled to obtain a fiber membrane.

[0053] The needle has an inner diameter of 0.3~0.8mm, the high voltage power supply is 5~20kV, the flow rate of the injection pump is 0.5~2ml / h, the distance between the polymer jet and the plate is 12~18cm, and the spinning time is 1~3h.

[0054] Electrospinning induces the formation of submicron fiber interwoven structures with controllable diameters using an electric field. Combined with precise control of flow rate, distance, and time, this allows for the construction of high-porosity, self-supporting, three-dimensional interconnected networks. This structure simultaneously achieves high ionic conductivity and enhanced mechanical strength, with a wide process parameter window, making it particularly suitable for the high viscosity characteristics of solid electrolyte precursors while avoiding the risk of interfacial side reactions.

[0055] In some embodiments, the vacuum drying is carried out in a vacuum oven at a temperature of 25~130℃ for 12~24 hours.

[0056] The present invention also provides an application of the above-mentioned sulfur-containing solid polymer electrolyte membrane, which is used in lithium-ion batteries. The lithium metal battery assembled with the electrolyte membrane has comprehensive advantages such as high safety, long cycle life, high energy density potential and excellent electrochemical performance.

[0057] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0058] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0059] Example 1

[0060] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0061] Step 1: Mix DMTS and DTBA at a mass ratio of 1:1 until homogeneous, and magnetically stir in an oil bath at 150°C for 120 min. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0062] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 40% by mass of LiTFSI and mix well. Stir magnetically at room temperature for 24 hours to obtain the precursor solution.

[0063] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.5 mm. Turn on the high-voltage power supply, control the high-voltage power supply to 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 1 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 15 cm, and control the spinning time to 2 h to obtain a fiber membrane. Then place the fiber membrane on the plate in an oven for 16 h, ensuring a vacuum atmosphere in the oven at a temperature of 120 °C. The dried polymer electrolyte membrane is cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA1)@LiTFSI.

[0064] P(DMTS1-DTBA1)@LiTFSI was stored in a glove box under an argon atmosphere (water <0.1ppm, oxygen <0.1ppm).

[0065] The P(DMTS1-DTBA1)@LiTFSI prepared in Example 1 was assembled with a positive electrode (lithium iron phosphate, LEP) and a negative electrode (lithium metal) to form a CR2025 button cell, and its performance was tested.

[0066] The positive electrode active material LEP, conductive agent (acetylene black), and binder (polyvinylidene fluoride, PVDF) were dissolved in N-methyl-2-pyrrolidone (NMP) at a mass ratio of 96.8:2.0:1.2 to prepare a positive electrode slurry, and 1% ethylene carbonate (EC) was added to wet the electrode. The positive electrode slurry was then coated onto an aluminum foil current collector and dried under vacuum to obtain the positive electrode sheet.

[0067] Before assembling CR2025 coin cells for cycle testing, ≤5μL of commercially available electrolyte (LiPF6 in EC / DMC) was dropped onto the surface of the P(DMTS1-DTBA2)@LiTFSI electrolyte membrane as an interface wetting agent, allowing it to penetrate to the electrolyte membrane and electrode interface via capillary action. This treatment was only used to improve initial interfacial compatibility during the testing phase. After addition, the membrane was allowed to stand for 5 minutes to allow the solvent to evaporate and form a thin wetting interface.

[0068] Example 2

[0069] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0070] Step 1: Mix DMTS and DTBA at a mass ratio of 1:3 until homogeneous, and magnetically stir in an oil bath at 150°C for 120 min. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0071] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 40% by mass of LiTFSI and mix well. Stir magnetically at room temperature for 24 hours to obtain the precursor solution.

[0072] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.5 mm. Turn on the high-voltage power supply, control the high-voltage power supply to 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 1 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 15 cm, and control the spinning time to 2 h to obtain a fiber membrane. Then place the plate in an oven for 16 h, ensuring a vacuum atmosphere in the oven at a temperature of 120 °C. The dried polymer electrolyte membrane is cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA3)@LiTFSI.

[0073] P(DMTS1-DTBA3)@LiTFSI was stored in a glove box under an argon atmosphere (water <0.1ppm, oxygen <0.1ppm).

[0074] The P(DMTS1-DTBA3)@LiTFSI prepared in Example 2 was assembled with positive and negative electrode sheets to form a CR2025 button cell, and its performance was tested.

[0075] like Figure 1 As shown, Figure 1 The XRD pattern of the sulfur-containing solid polymer electrolyte membrane prepared in Example 2 is shown below. Figure 1 The XRD pattern shows broad peaks in the polymer, indicating successful polymer synthesis.

[0076] Example 3

[0077] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0078] Step 1: Mix DMTS and DTBA at a mass ratio of 1:5 until homogeneous, and magnetically stir in an oil bath at 150°C for 120 min. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0079] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 40% by mass of LiTFSI and mix well. Stir magnetically at room temperature for 24 hours to obtain the precursor solution.

[0080] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.5 mm. Turn on the high-voltage power supply, control the high-voltage power supply at 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 1 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 15 cm, and control the spinning time to 2 h to obtain a fiber membrane. Then place the plate in an oven for 16 h, ensuring a vacuum atmosphere in the oven at a temperature of 120 °C. The dried polymer electrolyte membrane is cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA5)@LiTFSI.

[0081] P(DMTS1-DTBA5)@LiTFSI was stored in a glove box under an argon atmosphere (water <0.1ppm, oxygen <0.1ppm).

[0082] The P(DMTS1-DTBA5)@LiTFSI prepared in Example 3 was assembled with positive and negative electrode sheets to form a CR2025 button cell, and its performance was tested.

[0083] Example 4

[0084] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0085] Step 1: Mix DMTS and DTBA at a mass ratio of 1:6 until homogeneous, and magnetically stir in an oil bath at 180°C for 30 minutes. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0086] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 20% by mass of LiTFSI and mix well. Stir magnetically at room temperature for 12 hours to obtain the precursor solution.

[0087] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.3 mm. Turn on the high-voltage power supply, control the high-voltage power supply at 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 0.5 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 12 cm, and control the spinning time to 1 h to obtain a fiber membrane. Then place the plate in an oven for 12 h, ensuring a vacuum atmosphere in the oven at a temperature of 130 °C. The dried polymer electrolyte membrane is cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA6)@LiTFSI.

[0088] P(DMTS1-DTBA6)@LiTFSI was stored in a glove box under an argon atmosphere (water <0.1ppm, oxygen <0.1ppm).

[0089] The P(DMTS1-DTBA6)@LiTFSI prepared in Example 4 was assembled with positive and negative electrode sheets to form a CR2025 button cell, and its performance was tested.

[0090] Example 5

[0091] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0092] Step 1: Mix DMTS and DTBA at a mass ratio of 1:8 until homogeneous, and magnetically stir in an oil bath at 100°C for 60 min. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0093] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 60% by mass of LiTFSI and mix well. Stir magnetically at room temperature for 24 hours to obtain the precursor solution.

[0094] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.8 mm. Turn on the high-voltage power supply, control the high-voltage power supply at 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 2 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 18 cm, and control the spinning time to 3 h to obtain a fiber membrane. Then place the plate in an oven for 24 h, ensuring a vacuum atmosphere in the oven at a temperature of 25 °C. The dried polymer electrolyte membrane is cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA8)@LiTFSI.

[0095] P(DMTS1-DTBA8)@LiTFSI was stored in a glove box under an argon atmosphere (water <0.1ppm, oxygen <0.1ppm).

[0096] The P(DMTS1-DTBA8)@LiTFSI prepared in Example 5 was assembled with positive and negative electrode sheets to form a CR2025 button cell, and its performance was tested.

[0097] Example 6

[0098] This embodiment provides a method for preparing a sulfur-containing solid polymer electrolyte membrane, including the following steps:

[0099] Step 1: Mix DMTS and DTBA at a mass ratio of 1:10 until homogeneous, and magnetically stir in an oil bath at 160°C for 90 min. After reacting at high temperature, cool to room temperature to obtain a solid polymer.

[0100] Step 2: Dissolve the solid polymer obtained in Step 1 in DMF, add 80% by mass of LiTFSI and mix well. Stir magnetically at 60°C for 48 hours to obtain the precursor solution.

[0101] Step 3: Load the precursor solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.5 mm. Turn on the high-voltage power supply, controlling it at 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle tip. Start the injection pump to push the precursor solution at a flow rate of 1 ml / h, forming a continuous polymer jet under the action of the electric field. Directly spray the polymer jet onto the receiving plate, keeping the distance between the receiving plate and the polymer jet at 15 cm, and control the spinning time to 2 hours to obtain a fiber membrane. Then place the plate in an oven for 20 hours, ensuring a vacuum atmosphere in the oven at a temperature of 60°C. The dried polymer electrolyte membrane is then cut into 16 mm diameter discs using a punching machine to obtain a sulfur-containing solid polymer electrolyte membrane, denoted as P(DMTS1-DTBA). 10 @LiTFSI.

[0102] P(DMTS1-DTBA) 10 @LiTFSI is stored in a glove box under an argon atmosphere, with water <0.1ppm and oxygen <0.1ppm.

[0103] The P(DMTS1-DTBA) prepared in Example 6 10 The LiTFSI electrode was assembled with positive and negative electrodes to form a CR2025 button cell for performance testing.

[0104] Comparative Example 1

[0105] Comparative Example 1 provides a method for preparing a PEO@LiTFSI electrolyte membrane, comprising the following steps:

[0106] Step 1: Mix PEO and LiTFSI in a typical mixing ratio of EO:Li + =16:1 (mass ratio 10:4) dissolved in acetonitrile (ACN) solvent to obtain a mixed solution;

[0107] Step 2: Load the mixed solution into a syringe, allow it to stand to expel air bubbles, then install a needle with an inner diameter of 0.5 mm. Turn on the high-voltage power supply, control the high-voltage power supply at 5 kV, and gradually increase the voltage to 20 kV until a stable fiber jet is formed at the needle. Start the injection pump to push the precursor solution at a flow rate of 1 ml / h, forming a continuous polymer jet under the action of the electric field. Directively spray the polymer jet onto the receiving plate, making the distance between the receiving plate and the polymer jet 15 cm, and control the spinning time to 2 h to obtain a fiber membrane. Then, vacuum dry the membrane at 60°C for 24 h to dry the solvent. Then peel the membrane off the mold and cut it into 16 mm diameter discs using a punching machine to obtain the PEO@LiTFSI electrolyte membrane.

[0108] The PEO@LiTFSI electrolyte membrane prepared in Comparative Example 1 was assembled with positive and negative electrode sheets to form a battery, and its performance was tested.

[0109] Table 1. Basic performance parameters of the polymer electrolyte membranes prepared in Examples 1-6 and Comparative Example 1

[0110]

[0111] The polymer electrolyte membranes prepared in Examples 1-6 and Comparative Example 1 were subjected to basic performance tests, and the test results are shown in Table 1.

[0112] First, a single-factor comparative analysis was performed on Examples 1-3, and the electrochemical window order of Examples 1-3 was: Example 3 > Example 2 > Example 1. This is because the rigid benzene ring skeleton and disulfide bonds (-SS-) in DTBA endow it with excellent high-voltage oxidation resistance, effectively inhibiting the decomposition of DTBA at potentials >4.0V; while the flexible -S4- chain in DMT is prone to oxidative breakage at high voltages >4.1V, leading to decreased stability. In Example 3 (the mass ratio of DMTS to DTBA is 1:5), DTBA is the main component, thus exhibiting the widest electrochemical stability window.

[0113] Regarding ionic conductivity, the order is: Example 1 > Example 2 > Example 3 > Comparative Example 1. The flexible -S4-chains of DMT can form a structure favorable for Li... + The rapidly migrating "sulfur chain tunnels" significantly enhance ionic conductivity; however, the rigid benzene ring structure of DTBA hinders chain segment movement and inhibits ion migration. In Example 1 (DTBA:DMT=1:1), due to the highest proportion of DMT, the conductivity is close to that of a liquid electrolyte. This conclusion is consistent with impedance data (…). Figure 2 The results corroborate each other: Example 1 has the lowest impedance (185Ω), while Comparative Example 1 has the highest impedance (613Ω), showing a clear inverse relationship between conductivity and impedance.

[0114] In terms of mechanical strength, the tensile strength order was Example 3 > Example 2 > Example 1. The benzene ring structure of DTBA forms a physical cross-linking network through intermolecular π-π stacking, which greatly enhances the rigidity of the material; while the flexible long chain of DMT weakens the mechanical properties. The tensile strength of Example 3 (high DTBA content) reached 4.2 MPa, which is close to the requirements of commercial membranes, fully demonstrating the reinforcing effect of the rigid component.

[0115] A comprehensive analysis of the data in Table 1 shows that the sulfur-containing solid polymer electrolyte membranes prepared in Examples 1-6 significantly outperform Comparative Example 1 in key indicators. Specifically, the electrochemical window range of Examples 1-6 is 4.1V-4.65V, while that of Comparative Example 1 is only 3.9V, indicating that the sulfur-containing solid polymer electrolyte membranes prepared in the examples have stronger antioxidant capacity and can be matched with higher voltage electrode materials. In terms of ionic conductivity, Examples 1-6 are generally more than one order of magnitude higher than Comparative Example 1, and the tensile strength is significantly improved, proving that the technical solution of the present invention has a breakthrough advantage in balancing high ion transport efficiency and structural stability.

[0116] Table 2. Stability and cycling performance parameters of the polymer electrolyte membranes prepared in Examples 1-6 and Comparative Example 1

[0117]

[0118] As shown in Table 2, in Li + Regarding ion transference numbers, Example 1 > Example 2 > Example 3, mainly due to the sulfur atom of the -S4- chain in DMT and Li + Affinity (soft acid sulfur atom affinity for Li) + This forms a selective transport channel; while the carboxyl group (-COOH) of DTBA may capture Li + The lack of ion conductivity due to the benzene ring structure leads to a decrease in the migration number of samples with a high DTBA content (such as Example 3). In Example 1, when the ratio was 1:1, the migration number was significantly lower. + =0.45 is the optimal value.

[0119] Li-Li symmetric cell tests showed that the polarization degree was: Example 3 > Example 2 > Example 1. The flexible chain of DMT improved the uniformity of electrode / electrolyte interface contact and significantly reduced the interface impedance; conversely, the rigid benzene ring of DTBA caused point contact defects at the electrode / electrolyte interface, increased the resistance to ion migration, and caused the polarization voltage of Example 3 to continue to rise.

[0120] To further verify the effect of P(DMTS1-DTBA3)@LiTFSI on the stability of the lithium metal anode, SEM analysis was performed at 0.2 mA cm⁻¹. -1 The surface morphology of the lithium sheet in a Li-Li symmetric battery after 100 cycles at a current density is shown in Figure 3(a). After 100 cycles using the P(DMTS1-DTBA3)@LiTFSI electrolyte membrane, the lithium anode surface is smooth and dendrites are suppressed; while in Figure 3(b), PEO@LiTFSI shows lithium corrosion and uneven deposition, verifying the strong correlation between interface stability and polarization data.

[0121] The cycle retention rates were in the order of Example 3 > Example 2 > Example 1. This is because the mechanical strength (enhanced by physical cross-linking) and antioxidant properties (disulfide bonds and benzene rings) of DTBA jointly inhibit dendrite growth and decomposition side reactions, but at the cost of sacrificing ion transport rate; while DMT improves the conduction rate, it weakens the interfacial stability in long-term cycling.

[0122] like Figure 4 The figure shows the rate performance of LFP|P(DMTS1-DTBA2)@LiTFSI@LiTFSI|Li and LFP|PEO@LiTFSI|Li batteries prepared by the electrolyte membranes of Example 1 and Comparative Example 1 at 25°C. Figure 4 It can be observed that the discharge capacity of the lithium battery assembled using P(DMTS1-DTBA2)@LiTFSI is 153 mAh g at 0.1C, 0.2C, and 0.5C. -1 148mAh g -1 and 138mAh g -1 The discharge capacity of the lithium metal battery manufactured using PEO@LiTFSI is 111 mAh g at 0.1C, 0.2C, and 0.5C. -1 104mAh g -1 and 97mAh g -1 When the discharge rate is reduced to 0.1C, the discharge capacity of the lithium battery using P(DMTS1-DTBA2)@LiTFSI increases to 152 mAh g. -1 The discharge capacity of the lithium battery using LFP|PEO@LiTFSI|Li only increased to 108 mAh g. -1 This indicates that P(DMTS1-DTBA2)@LiTFSI exhibits excellent rate performance and capacity recovery. This is mainly due to the dynamic flexibility of the sulfur chain promoting ion migration, while the dual coordination of the amino groups stabilizes ion binding. The synergistic effect of these two factors significantly enhances the ion transport rate, resulting in less capacity loss during fast charging and discharging.

[0123] A comprehensive analysis of the data in Table 2 shows that the Li-Li symmetric polarization voltages (32-177mV) in all embodiments are significantly lower than those in Comparative Example 1 (330mV), with a maximum reduction of 90.3%, demonstrating a substantial decrease in electrode / electrolyte interface impedance obtained in the embodiments of this invention. The cycle retention rates of Examples 1-6 are all superior to those of Comparative Example 1, and the Li... + The migration number increased by 16%-18%, indicating that the battery assembled with the sulfur-containing solid polymer electrolyte membrane prepared by the method of the present invention can effectively improve cycle life and ion transport efficiency.

[0124] The data above shows that different embodiments have their own performance advantages due to differences in component ratios, and the formulation should be selected according to the specific needs of the application scenario. For high-power battery scenarios, Embodiment 1 is selected, which achieves optimal ionic conductivity and low polarization characteristics based on the "sulfur chain tunnel" effect formed by the highly flexible chain dominated by DMT, meeting the requirements of fast charging and high-rate discharge. For long cycle life scenarios, Embodiment 2 is selected, which maintains high ion mobility while also possessing the enhanced mechanical strength of DTBA, ensuring structural stability during cycling, controllable polarization, and excellent capacity retention. For high-voltage systems, Embodiment 3 is adopted, relying on the rigid benzene ring and disulfide bond antioxidant properties of DTBA to broaden the electrochemical window, making it suitable for high-voltage battery environments such as lithium cobalt oxide and high-nickel cathodes.

[0125] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A sulfur-containing solid polymer electrolyte membrane, characterized in that, The sulfur-containing solid polymer electrolyte membrane is obtained by uniformly mixing dimethyl tetrasulfide and dithiodibenzoic acid, followed by polycondensation reaction to obtain a solid polymer, then dissolving the solid polymer in N,N-dimethylamide to obtain a mixed solution, adding lithium bis(trifluoromethanesulfonyl)imide to the mixed solution and mixing uniformly to obtain a precursor solution, then electrospinning the precursor solution to form a fiber membrane, and finally drying it under vacuum. The general structural formula of the sulfur-containing solid polymer is: In the formula, n is the degree of aggregation, and 5000 < n < 50000.

2. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, The thickness of the sulfur-containing solid polymer electrolyte membrane is 70µm±5µm.

3. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, The mass ratio of dimethyltetrasulfide to dithiodibenzoic acid is 1:(1~10).

4. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, The polycondensation reaction is carried out in an oil bath at a temperature of 100~180℃ for 30~120 min. After the reaction is completed, the polymer is cooled to room temperature to obtain a solid polymer.

5. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, The amount of lithium bis(trifluoromethanesulfonyl)imide added is 20% to 80% of the total mass of dimethyl tetrasulfide and dithiodibenzoic acid.

6. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, Lithium bis(trifluoromethanesulfonyl)imide was added to the mixed solution and magnetically stirred at a temperature of 25-60°C for 12-48 hours until the mixture was homogeneous to obtain the precursor solution.

7. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, During the electrospinning process: The needle has an inner diameter of 0.3~0.8mm, a voltage of 5~20kV, a solution flow rate of 0.5~2ml / h, a distance of 12~18cm between the needle and the receiving plate, and a spinning time of 1~3h.

8. The sulfur-containing solid polymer electrolyte membrane according to claim 1, characterized in that, The vacuum drying temperature is 25~130℃, and the time is 12~24h.

9. The application of a sulfur-containing solid polymer electrolyte membrane according to any one of claims 1 to 8, characterized in that, The sulfur-containing solid polymer electrolyte membrane is used in lithium-ion batteries.

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