Sulfide solid electrolyte, method for preparing the same, and supercapacitor

Abstract

The application discloses a sulfide solid electrolyte, a preparation method thereof and a super capacitor. The sulfide solid electrolyte comprises an organic-inorganic composite film generated by a curing reaction of a raw material system. The raw material system comprises a first monomer, a second monomer, a lithium salt, a siloxane prepolymer and an initiator. The first monomer is N,N'-1,3-propanediyl bis(oxazolidine 2-ketone), and the second monomer is 4,4'-thiobisphenol diglycidyl ether. The application is based on the composite system sulfide solid electrolyte of N,N'-1,3-propanediyl bis(oxazolidine 2-ketone) and 4,4'-thiobisphenol diglycidyl ether, and the modification of the siloxane prepolymer and the optimized process parameters, so that the defects of the prior art can be effectively solved.

Description

Technical Field

[0001] This application relates to the technical field of supercapacitors, and more particularly to sulfide solid electrolytes, their preparation methods, and supercapacitors. Background Technology

[0002] Supercapacitors, as a novel energy storage device, possess advantages such as high power density, fast charging and discharging speed, long cycle life, and wide operating temperature range, and have broad application prospects in fields such as new energy vehicles, portable electronic devices, and smart grid energy storage. The electrolyte, as the core component of a supercapacitor, directly determines the device's ion transport efficiency, electrochemical stability, cycle life, and safety performance, and is a key factor restricting the development of supercapacitors towards higher power and higher stability.

[0003] Currently, electrolytes commonly used in supercapacitors are mainly divided into two categories: liquid electrolytes and solid electrolytes. While liquid electrolytes have the advantage of high ionic conductivity, they also suffer from drawbacks such as leakage risk, a narrow electrochemical stability window, and easy decomposition at high temperatures, severely impacting the safety and lifespan of supercapacitors. Solid electrolytes, on the other hand, have become a research hotspot in the electrolyte field due to their advantages such as no leakage, high safety, and adaptability to a wide voltage window. Among these, sulfide solid electrolytes have attracted widespread attention because the introduction of sulfur can optimize ion transport channels and improve interfacial compatibility; however, existing sulfide solid electrolytes still face many technical bottlenecks.

[0004] Existing sulfide solid electrolytes mostly use polyethylene glycol (PEG) monomers as the matrix, combined with simple sulfide crosslinking agents. These systems suffer from poor crosslinking network stability, insufficient ionic conductivity, and a narrow electrochemical stability window. Furthermore, some systems introduce inorganic fillers to improve mechanical strength, but this can easily lead to impeded ion transport, or poor compatibility between the filler and the organic matrix, causing the electrolyte membrane to crack easily and shorten cycle life. In addition, the unreasonable lithium salt ratio and curing process parameters in existing formulations further exacerbate the imbalance in the overall performance of the electrolyte, making it difficult to meet the comprehensive requirements of high-power supercapacitors for electrolytes with "high ionic conductivity, wide stability window, excellent mechanical properties, and long cycle life."

[0005] To address the aforementioned technical shortcomings, there is an urgent need to develop a novel sulfide solid electrolyte system. By optimizing the combination of core monomers, introducing functional components, and controlling the preparation process, the system can achieve a synergistic improvement in ionic conductivity, electrochemical stability, mechanical strength, and cycle life, thereby promoting the large-scale application of supercapacitors in the field of high-end energy storage. Summary of the Invention

[0006] This application proposes a sulfide solid electrolyte, its preparation method, and a supercapacitor to address the deficiencies of the prior art.

[0007] According to a first aspect of the embodiments of this application, a sulfide solid electrolyte is provided, comprising an organic-inorganic composite membrane generated from a raw material system through a curing reaction.

[0008] The raw material system includes a first monomer, a second monomer, a lithium salt, a siloxane prepolymer, and an initiator, wherein the first monomer is N,N′-1,3 Propylenediol (oxazolidine) 2 (ketone), the second monomer is 4,4'-thiobisphenol diglycidyl ether.

[0009] In some embodiments, the mass ratio of the first monomer to the second monomer ranges from 100:30 to 100:50.

[0010] In some embodiments, the siloxane prepolymer is prepared by partial hydrolysis and condensation of tetraethyl orthosilicate, wherein the amount of tetraethyl orthosilicate is 10% to 20% of the mass of the first monomer.

[0011] In some embodiments, the lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, wherein the mass of the lithium bis(trifluoromethanesulfonyl)imide is 20 to 25 parts and the mass of the lithium bis(fluorosulfonyl)imide is 5 to 10 parts.

[0012] In some embodiments, the initiator includes a photoinitiator and a thermal initiator; the photoinitiator is dimethyl benzoate, and the amount of dimethyl benzoate is 1% to 1.5% of the mass of the first monomer; the thermal initiator is benzoyl peroxide.

[0013] According to a second aspect of this application, a preparation method is provided for preparing a sulfide solid electrolyte as described above, comprising:

[0014] The first monomer, the second monomer, the lithium salt, and the initiator were dried separately.

[0015] In an inert atmosphere, tetraethyl orthosilicate, an organic solvent, and an acid catalyst are mixed and partially hydrolyzed and condensed to obtain a siloxane prepolymer.

[0016] The first monomer, the second monomer, and the lithium salt, after being dried, are mixed with the siloxane prepolymer and then subjected to high-speed dispersion and ultrasonic treatment to generate a homogeneous composite premix.

[0017] An initiator is added to the composite premixed liquid, and after stirring and adjusting to a preset viscosity, a film is formed on the substrate and pre-cured by ultraviolet light irradiation to obtain a semi-cured film.

[0018] The semi-cured film is subjected to segmented heat treatment under vacuum and inert atmosphere to deeply crosslink the organic phase and completely cure the inorganic phase, forming a cured film with an organic-inorganic composite network.

[0019] The cured film is vacuum dried to obtain the sulfide solid electrolyte.

[0020] In some embodiments, the segmented heat treatment includes a first stage and a second stage, wherein the first stage includes holding at 80-90°C for 2-3 hours and the second stage includes holding at 120-140°C for 1-2 hours.

[0021] In some embodiments, the UV irradiation pre-curing time is 100 to 200 seconds; and / or, the vacuum drying temperature is 60-80°C, and the vacuum drying time is 6-10 hours.

[0022] In some embodiments, the high-speed dispersion rotation speed is 5000-10000 rpm, the high-speed dispersion time is 30-60 minutes, and the ultrasonic treatment time is 30-60 minutes.

[0023] According to a third aspect of this application, a supercapacitor is provided, comprising a positive electrode, a negative electrode, and a sulfide solid electrolyte as described above disposed between the positive and negative electrodes; the positive electrode comprises lithium nickel cobalt manganese oxide and activated carbon, and the negative electrode comprises activated carbon.

[0024] The beneficial effects of the sulfide solid electrolyte and its preparation method in this application, and the supercapacitor, include at least the following:

[0025] The embodiments in this application are based on N,N′-1,3 Propylenediol (oxazolidine) 2 The multi-dimensional synergistic effect of the oxazolidinone ring (BOZP) and 4,4'-thiobisphenol diglycidyl ether (TDGE) composite monomers, siloxane prepolymers, LiTFSI / LiFSI composite lithium salts, and photo-thermal composite initiation system breaks through the technical bottleneck of existing sulfur-containing polymer electrolytes at the mechanistic level: Compared with the low ion dissociation efficiency of single ether-coordinated monomers and the easy aggregation of sulfur atoms in diphenyl disulfide in existing technologies, the oxazolidinone ring (O, N atoms) of BOZP and the thioether bond (S atom) of TDGE form an "ONS" multidentate coordination environment, which can significantly improve the efficiency of Li... +The degree of dissociation is improved, and the two components form a dense three-dimensional cross-linked network through epoxy-methylene ring-opening condensation, preventing ion channel breakage. Addressing the shortcomings of poor mechanical strength in pure organic electrolytes and easy phase separation in pure inorganic dopants, the siloxane prepolymer is bonded to the organic monomer via hydrogen bonds. Its Si-O-Si rigid segments enhance the tensile strength of the film and, with the assistance of Si-O atoms, coordinate Li. + By constructing a continuous organic-inorganic ion channel, the room-temperature ion conductivity was significantly improved. Compared to the limitations of single LiTFSI lithium salt, which exhibits slow migration and high interfacial impedance, a mixture of LiTFSI and LiFSI in a specific ratio was developed, which utilizes TFSI... - Weakening Li + Association with anions, aided by FSI - A thin and stable SEI film is formed on the negative electrode surface to reduce interfacial impedance. The photo-thermal composite initiation system first fixes the film structure rapidly with ultraviolet light, and then achieves deep cross-linking through segmented thermal polymerization. This avoids the problems of uneven film layer or insufficient internal cross-linking caused by single initiation. At the same time, the high bond energy of siloxane and the heterocyclic structure of BOZP synergistically improve thermal stability. In the end, it comprehensively surpasses the existing technology in four core dimensions: ion conduction, interfacial compatibility, mechanical properties and thermal stability, and achieves a performance breakthrough of sulfide solid electrolyte. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of a preparation method according to an embodiment of this application;

[0027] Figure 2 This is a diagram illustrating the electronic conductivity results of an embodiment of this application;

[0028] Figure 3 This is a diagram illustrating the impedance results of an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the sulfur-containing polymer electrolyte and its preparation method will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of this application. Obviously, the described embodiments are only some embodiments of the embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed embodiments of the present application, but merely to illustrate selected embodiments of the present application. Other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are all within the scope of protection of the embodiments of the present application.

[0031] This application discloses a sulfide solid electrolyte, its preparation method, and a supercapacitor. The preparation method is used to prepare the sulfide solid electrolyte and is implemented based on the supercapacitor. The purpose is to add sulfur-containing functional additives to the solid electrolyte membrane and perform crosslinking polymerization using a crosslinking agent, based on N,N′-1,3 Propylenediol (oxazolidine) 2 The composite system of sulfide solid electrolytes of ketone (BOZP) and 4,4'-thiobisphenol diglycidyl ether (TDGE), combined with the modification effect of siloxane prepolymer and optimized process parameters, effectively solves the shortcomings of existing technologies.

[0032] This is a sulfide solid electrolyte, comprising an organic-inorganic composite membrane generated from a raw material system through a curing reaction.

[0033] The raw material system includes a first monomer, a second monomer, a lithium salt, a siloxane prepolymer, and an initiator.

[0034] For example, the first monomer is N,N′-1,3 Propylenediol (oxazolidine) 2 (ketone), the second monomer is 4,4'-thiobisphenol diglycidyl ether.

[0035] In some embodiments, the mass ratio of the first monomer to the second monomer ranges from 100:30 to 100:50.

[0036] In some embodiments, the siloxane prepolymer is prepared by partial hydrolysis and condensation of tetraethyl orthosilicate, wherein the amount of tetraethyl orthosilicate is 10% to 20% of the mass of the first monomer.

[0037] In some embodiments, the lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, wherein the lithium bis(trifluoromethanesulfonyl)imide is present in a mass of 20 to 25 parts and the lithium bis(fluorosulfonyl)imide is present in a mass of 5 to 10 parts.

[0038] In some embodiments, the initiator includes a photoinitiator and a thermal initiator; the photoinitiator is benzoin dimethyl ether, and the amount of benzoin dimethyl ether is 1% to 1.5% of the mass of the first monomer; the thermal initiator is benzoyl peroxide.

[0039] This application discloses a sulfide solid electrolyte, which is an organic-inorganic composite membrane formed through a curing reaction. The core feature of this composite membrane is that it is generated from a specific raw material system containing the following key components: a first monomer, a second monomer, a lithium salt, a siloxane prepolymer, and an initiator. For example, the first monomer is N,N′-1,3 Propylenediol (oxazolidine) 2 The first monomer, serving as one of the reaction backbones, possesses an oxazolidinone group with high reactivity, facilitating the formation of a cross-linked network structure. The second monomer is 4,4'-thiobisphenol diglycidyl ether. The epoxy group in the second monomer can undergo ring-opening polymerization with the first monomer, while the thioether bond may contribute to improving the electrolyte's flexibility and lithium-ion transport capacity. The lithium salt serves as a lithium-ion source in the system, ensuring the electrolyte's ionic conductivity. The introduction of the siloxane prepolymer aims to utilize the flexibility and thermal stability of the siloxane segments to optimize the mechanical properties (such as flexibility) of the composite membrane and achieve good compatibility with the inorganic components. The initiator is used to initiate the curing and cross-linking reaction between the first and second monomers, which is crucial for forming a stable three-dimensional network structure. Under specific conditions, the above raw materials undergo a curing reaction, ultimately forming an organic-inorganic composite membrane with the cross-linked polymer as the continuous phase and uniformly dispersed lithium salt and siloxane-derived structures as functional phases. This unique composite structure is expected to synergistically improve the overall performance of the electrolyte, especially its ionic conductivity, which can reach or exceed the level of existing high-performance sulfide electrolytes, while also possessing good mechanical properties and interfacial compatibility.

[0040] See attached document Figure 1 As shown in the embodiments of this application, a preparation method is also disclosed for preparing the above-mentioned sulfide solid electrolyte, including the following steps 110-160.

[0041] Step 110: Dry the first monomer, the second monomer, the lithium salt and the initiator respectively.

[0042] This step can also be understood as the raw material pretreatment stage.

[0043] For example, the drying process of the first monomer, the second monomer, the lithium salt, and the initiator includes: drying the first monomer (N,N′-1,3) separately. Propylenediol (oxazolidine) 2 The first monomer (ketone) and the second monomer (4,4'-thiobisphenol diglycidyl ether) were dried in a vacuum drying oven at 60°C for 16 h; the lithium salt (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI and lithium bis(fluorosulfonyl)imide, LiFSI) were dried in a vacuum drying oven at 80°C for 24 h; the initiator (benzoyl peroxide, DMPA) and the thermal initiator (benzoyl peroxide, BPO, purity ≥98%) were recrystallized from anhydrous tetrahydrofuran (THF) and dried in a vacuum drying oven at 40°C for 10 h; tetraethyl orthosilicate (TEOS) and 0.1 mol / L hydrochloric acid were mixed at a volume ratio of 10:0.05, anhydrous THF was added, and the mixture was stirred at 45°C for 1.5 h to obtain the siloxane prepolymer.

[0044] In some implementations, the N,N′-1,3 Propylenediol (oxazolidine) 2 The mass ratio of ketone (BOZP) to 4,4'-thiobisphenol diglycidyl ether (TDGE) is 100:(30-50).

[0045] Step 110 in this embodiment aims to completely remove the moisture adsorbed by the raw material, so as to avoid water from having an adverse effect on the sulfide material in subsequent processes.

[0046] Step 120: Under an inert atmosphere, tetraethyl orthosilicate, organic solvent and acid catalyst are mixed and partially hydrolyzed and condensed to obtain siloxane prepolymer.

[0047] Step 120 can be understood as the synthesis process of siloxane prepolymer.

[0048] For example, the partial hydrolysis and condensation of tetraethyl orthosilicate, organic solvent and acid catalyst under an inert atmosphere to obtain a siloxane prepolymer includes: measuring tetraethyl orthosilicate (TEOS), anhydrous THF and 0.1 mol / L hydrochloric acid in a certain volume ratio in an argon-protected glove box, placing them in a three-necked flask, stirring magnetically for a certain time, raising to a certain temperature and holding for partial hydrolysis and condensation to obtain a transparent siloxane prepolymer, and cooling to room temperature for later use.

[0049] Step 130: The first monomer, the second monomer, the lithium salt, and the siloxane prepolymer after drying are mixed and then dispersed at high speed and subjected to ultrasonic treatment to generate a homogeneous composite premix.

[0050] Step 130 can be understood as the preparation process of the composite premixed liquid.

[0051] In some embodiments, the high-speed dispersion rotation speed is 5000-10000 rpm, the high-speed dispersion time is 30-60 minutes, and the ultrasonic treatment time is 30-60 minutes.

[0052] For example, the first monomer, the second monomer, the lithium salt, and the siloxane prepolymer, after drying, are mixed and then dispersed at high speed and ultrasonically treated to generate a homogeneous composite premix. This process includes: weighing pretreated BOZP, TDGE, LiTFSI, and LiFSI at a specific mass ratio in an argon-protected glove box, adding the siloxane prepolymer, pouring it into a disperser, dispersing it at a specific speed for a specific time, and then transferring it to an ultrasonic cleaner. After ultrasonic treatment, a homogeneous and stable composite premix is ​​obtained. For instance, in an argon-protected glove box, BOZP, TDGE, LiTFSI, and LiFSI are weighed at a mass ratio of 100:40:25:5, and 10% of the total mass of BOZP and TDGE siloxane prepolymer is added. The mixture is sheared at 8000 r / min for 60 min and ultrasonically treated at 35°C for 50 min.

[0053] Step 140: Add an initiator to the composite premixed liquid, stir and adjust to the preset viscosity, form a film on the substrate and pre-cur it by ultraviolet light irradiation to obtain a semi-cured film.

[0054] Step 140 can be understood as the film formation and UV pre-curing process.

[0055] In some embodiments, the UV irradiation pre-curing time is 100 to 200 seconds; and / or, the vacuum drying temperature is 60-80°C, and the vacuum drying time is 6-10 hours.

[0056] For example, the process of adding an initiator to the composite premix, stirring to adjust to a preset viscosity, forming a film on a substrate, and pre-curing with ultraviolet light to obtain a semi-cured film includes: adding DMPA and BPO to the composite premix, magnetically stirring at 30°C for a certain time to completely dissolve the initiator, and simultaneously fine-tuning the viscosity of the system with anhydrous THF to form a polymerization precursor system. The precursor system is transferred to a quartz substrate in a spin coater and spin-coated for 30 seconds at a certain speed in a glove box to form a uniform liquid film. The substrate is then transferred to an ultraviolet curing apparatus and irradiated for a period of time under argon protection to complete photo-initiated prepolymerization and obtain a semi-cured film. For example, 1.2% (by weight) of DMPA and 0.5% (by weight) of BPO are added, stirred at 30°C for 40 minutes, and the viscosity is adjusted to 2500±50 mPa with anhydrous THF. Spin coating at 3000 r / min for 30 s, followed by pre-curing under 30 mW / cm² UV light (365 nm) for 200 s.

[0057] Step 150: The semi-cured film is subjected to segmented heat treatment under vacuum and inert atmosphere to deeply crosslink the organic phase and completely cure the inorganic phase, forming a cured film with an organic-inorganic composite network.

[0058] Step 150 can be understood as a segmented heat treatment process.

[0059] In some embodiments, the segmented heat treatment includes a first stage and a second stage, wherein the first stage includes holding at 80-90°C for 2-3 hours and the second stage includes holding at 120-140°C for 1-2 hours.

[0060] For example, the semi-cured film is subjected to segmented heat treatment under vacuum and an inert atmosphere to achieve deep crosslinking of the organic phase and complete curing of the inorganic phase, forming a cured film with an organic-inorganic composite network. This includes: placing the semi-cured film along with a substrate into a programmed temperature-controlled vacuum reactor, and performing segmented treatment under an argon atmosphere and a vacuum of 0.08 MPa: In the first stage, the temperature is raised to a certain level and held for a certain time to induce BPO decomposition and promote deep crosslinking of the organic phase; in the second stage, the temperature is raised to a certain level and held for a certain time to drive the complete condensation and curing of the siloxane prepolymer, forming the organic-inorganic composite network. For example: under an argon atmosphere of 0.08 MPa, thermal crosslinking is performed at 85°C for 3 hours, followed by curing at 120°C for 2 hours.

[0061] Step 160: The cured film is vacuum dried to obtain a sulfide solid electrolyte.

[0062] Step 160 can be understood as the final drying process.

[0063] For example, the process of vacuum drying the cured film to obtain the sulfide solid electrolyte includes: after the reaction is completed, cooling the furnace to room temperature, peeling the composite film off the substrate, transferring it to a vacuum drying oven, and vacuum drying at a certain temperature for a certain time to remove residual solvents and oligomers, ultimately obtaining a sulfur-containing polymer electrolyte film of uniform thickness. For example, vacuum drying at 70°C for 8 hours yields a sulfide solid electrolyte film.

[0064] The embodiments in this application are based on N,N′-1,3 Propylenediol (oxazolidine) 2 The multi-dimensional synergistic effect of the oxazolidinone ring (BOZP) and 4,4'-thiobisphenol diglycidyl ether (TDGE) composite monomers, siloxane prepolymers, LiTFSI / LiFSI composite lithium salts, and photo-thermal composite initiation system breaks through the technical bottleneck of existing sulfur-containing polymer electrolytes at the mechanistic level: Compared with the low ion dissociation efficiency of single ether-coordinated monomers and the easy aggregation of sulfur atoms in diphenyl disulfide in existing technologies, the oxazolidinone ring (O, N atoms) of BOZP and the thioether bond (S atom) of TDGE form an "ONS" multidentate coordination environment, which can significantly improve the efficiency of Li... +The degree of dissociation is improved, and the two components form a dense three-dimensional cross-linked network through epoxy-methylene ring-opening condensation, preventing ion channel breakage. Addressing the shortcomings of poor mechanical strength in pure organic electrolytes and easy phase separation in pure inorganic dopants, the siloxane prepolymer is bonded to the organic monomer via hydrogen bonds. Its Si-O-Si rigid segments enhance the tensile strength of the film and, with the assistance of Si-O atoms, coordinate Li. + By constructing a continuous organic-inorganic ion channel, the room-temperature ion conductivity was significantly improved. Compared to the limitations of single LiTFSI lithium salt, which exhibits slow migration and high interfacial impedance, a mixture of LiTFSI and LiFSI in a specific ratio was developed, which utilizes TFSI... - Weakening Li + Association with anions, aided by FSI - A thin and stable SEI film is formed on the negative electrode surface to reduce interfacial impedance. The photo-thermal composite initiation system first fixes the film structure rapidly with ultraviolet light, and then achieves deep cross-linking through segmented thermal polymerization. This avoids the problems of uneven film layer or insufficient internal cross-linking caused by single initiation. At the same time, the high bond energy of siloxane and the heterocyclic structure of BOZP synergistically improve thermal stability. In the end, it comprehensively surpasses the existing technology in four core dimensions: ion conduction, interfacial compatibility, mechanical properties and thermal stability, and achieves a performance breakthrough of sulfide solid electrolyte.

[0065] This application also discloses a supercapacitor, including a positive electrode, a negative electrode, and a sulfide solid electrolyte disposed between the positive and negative electrodes; the positive electrode comprises lithium nickel cobalt manganese oxide and activated carbon, and the negative electrode comprises activated carbon.

[0066] In some embodiments, the supercapacitors of this application are prepared in the following order: positive electrode shell, positive electrode sheet, polymer electrolyte, negative electrode sheet, stainless steel sheet, spring sheet, and negative electrode shell. The positive electrode sheet is made of NCM811 and activated carbon, and the negative electrode is made of activated carbon.

[0067] For a better illustration of this application, please refer to the appendix. Figure 2-3 The present application is further illustrated by the following embodiments 1 to 7 and comparative examples 1 and 2.

[0068] Example 1 includes the following steps S1-S5.

[0069] Step S1: Raw material pretreatment stage, N,N′-1,3 Propylenediol (oxazolidine) 2 BOZP (a ketone) and 4,4'-thiobisphenol diglycidyl ether (TDGE) were dried in a vacuum oven at 60°C for 16 h; lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) were dried in a vacuum oven at 80°C for 24 h; dimethyl benzoate (DMPA) and benzoyl peroxide (BPO, purity ≥98%) were recrystallized from anhydrous tetrahydrofuran (THF) and dried in a vacuum oven at 40°C for 10 h; tetraethyl orthosilicate (TEOS) and 0.1 mol / L hydrochloric acid were mixed at a volume ratio of 10:0.05, anhydrous THF was added, and the mixture was stirred at 45°C for 1.5 h to obtain a siloxane prepolymer.

[0070] Step S2: In the preparation stage of the composite premixed liquid, BOZP, TDGE, LiTFSI and LiFSI are weighed in an argon glove box at a mass ratio of 100:40:25:5. 10% of the total mass of BOZP and TDGE is added to the siloxane prepolymer. The mixture is sheared and dispersed at 8000 r / min for 60 min and then sonicated at 35℃ for 50 min.

[0071] Step S3: Thermally initiated film formation stage, add 1.2% DMPA and 0.5% BPO by weight of BOZP, stir at 30℃ for 40 min, and adjust the viscosity to 2500±50 mPa with anhydrous THF. Spin coating at 3000 r / min for 30 s, followed by pre-curing under 30 mW / cm² UV light (365 nm) for 200 s.

[0072] Step S4: Thermal crosslinking and post-treatment stage, under 0.08MPa argon atmosphere, thermal crosslinking at 85℃ for 3h, curing at 120℃ for 2h; vacuum drying at 70℃ for 8h to obtain sulfide solid electrolyte membrane.

[0073] Step S5: Supercapacitor fabrication stage. The supercapacitor is fabricated in the following order: positive electrode shell, positive electrode sheet, polymer electrolyte, negative electrode sheet, stainless steel sheet, spring sheet, and negative electrode shell. The positive electrode sheet is a mixture of NCM811 and activated carbon, and the negative electrode is made of activated carbon.

[0074] Example 2 differs from Example 1 only in the amount of TDGE used. The mass ratio of BOZP to TDGE is adjusted from 100:40 to 100:30. Everything else is the same as in Example 1.

[0075] Example 3 differs from Example 1 only in the amount of siloxane prepolymer used, which is adjusted from 10% of the total mass of BOZP and TDGE to 15% of the total mass of BOZP and TDGE. Everything else is the same as in Example 1.

[0076] Example 4 differs from Example 1 only in the lithium salt ratio. The mass ratio of LiTFSI to LiFSI is adjusted from 25:5 to 20:10. Everything else is the same as in Example 1.

[0077] Example 5 differs from Example 1 only in the UV curing time; the UV irradiation time of 30mW / cm² for 200s is adjusted to 150s, while the rest is the same as Example 1.

[0078] Example 6 differs from Example 1 only in the thermal crosslinking temperature. Instead of thermal crosslinking at 85°C for 3 hours and curing at 120°C for 2 hours, the thermal crosslinking temperature was adjusted to 90°C for 2.5 hours and curing at 125°C for 1.5 hours. All other conditions are the same as in Example 1.

[0079] Example 7 differs from Example 1 only in the amount of DMPA used. Instead of adding 1.2% BOZP by mass, the DMPA is changed to adding 1.0% BOZP by mass. Everything else is the same as in Example 1.

[0080] Comparative Example 1 differs from Example 1 only in that the core monomers are replaced. BOZP+TDGE is replaced with polyethylene glycol dimethacrylate (PEGDMA, number average molecular weight 500) + diphenyl disulfide (DPDS), while maintaining the PEGDMA to DPDS mass ratio of 100:40. Everything else is the same as in Example 1.

[0081] Comparative Example 2 differs from Example 1 only in that the siloxane prepolymer is removed and no siloxane prepolymer is added during the preparation of the composite premix; otherwise, it is the same as Example 1.

[0082] In addition, this specific embodiment also discloses a method for preparing a button-type supercapacitor, including: preparation of a positive electrode, preparation of a negative electrode, device assembly, ionic conductivity testing, electrochemical stability window testing, and tensile strength testing.

[0083] For example, the preparation of the positive electrode sheet includes: mixing NCM811 (positive electrode active material), activated carbon (conductive agent and active material), and polyvinylidene fluoride (PVDF, binder) in a mass ratio of 80:15:5, adding an appropriate amount of N-methylpyrrolidone (NMP), and grinding in an agate mortar for 30 min to prepare a uniform positive electrode slurry; uniformly coating the positive electrode slurry onto an aluminum foil current collector with a coating thickness controlled at 100±5μm, and then drying it in a vacuum drying oven at 60℃ for 12 h to remove the solvent; rolling the dried electrode sheet on a roller press with a pressure of 5MPa, and cutting it into a circular positive electrode sheet with a diameter of 12mm for later use.

[0084] For example, the preparation of the negative electrode sheet includes: mixing activated carbon (negative electrode active material) and PVDF (binder) at a mass ratio of 95:5, adding an appropriate amount of NMP, and grinding for 25 min to prepare a uniform negative electrode slurry; coating the negative electrode slurry onto a copper foil current collector with a coating thickness of 90±5μm, vacuum drying at 60℃ for 12 h, and then rolling it with a pressure of 4MPa to cut it into a circular negative electrode sheet with a diameter of 13mm (slightly larger than the positive electrode sheet to avoid electrode misalignment), for later use.

[0085] For example, the device assembly includes: assembling a button-type supercapacitor (CR2032 type) in an argon glove box (water and oxygen content both <1ppm), with the assembly sequence as follows: positive electrode shell → positive electrode sheet → sulfide solid electrolyte membrane → negative electrode sheet → stainless steel gasket → spring sheet → negative electrode shell; wherein, the electrolyte membrane is cut into a circle with a diameter of 14mm to cover the entire positive and negative electrode sheets; during the assembly process, ensure that all components are aligned and without misalignment, and then seal with a button battery sealing machine at a pressure of 10MPa, and perform performance testing after standing for 24 hours.

[0086] For example, the ionic conductivity test includes: testing the ionic conductivity of the electrolyte membrane using AC impedance spectroscopy; cutting the electrolyte membrane into a 12mm diameter, uniformly thick circular sheet, clamping it between two stainless steel electrodes, and assembling it into a symmetrical cell; and testing using an electrochemical workstation (CHI660E) at 25°C with a frequency range of 10 Hz. - ²~10 6 Hz, amplitude of 5mV; read the body resistance (R) based on the semicircle diameter in the impedance spectrum. a ), combined with the formula σ=L / (R a The ionic conductivity (σ) is calculated using the formula (×S), where L is the electrolyte membrane thickness and S is the contact area between the electrode and the electrolyte membrane (see appendix for results). Figure 2-3 (As shown).

[0087] For example, the electrochemical stability window test includes: assembling a Li / electrolyte / Li symmetric battery using a lithium sheet as the reference electrode and counter electrode, and an electrolyte membrane as the electrolyte; employing linear sweep voltammetry (LSV) with a scan range of 0–5 V and a scan rate of 1 mV / s; the voltage at which the current density suddenly increases is the upper limit of the electrochemical stability window. Constant current charge-discharge tests are performed using a Blue Battery Testing System (CT2001A) at a test temperature of 25°C, a voltage range of 0–1.8 V, and a current density of 1 A / g; the initial charge-discharge capacity is recorded, followed by cycle testing.

[0088] For example, the tensile strength test includes: cutting the electrolyte membrane into a rectangular specimen of 10mm × 50mm, performing a tensile test using an electronic universal testing machine (WDW-1) at a tensile rate of 5mm / min and a test temperature of 25℃, recording the maximum tensile force when the specimen breaks, and calculating the tensile strength (σ) using the formula σ=F / S, where F is the maximum tensile force and S is the cross-sectional area of ​​the specimen (width × thickness).

[0089] Table 1 below shows the implementation data for Examples 1 to 7, as well as Comparative Examples 1 and 2:

[0090] Table 1: Parameter Table of Examples 1 to 7 and Comparative Examples 1 and 2

[0091]

[0092] Based on the appendix Figure 2-3 As shown in Table 1 above, Example 1, as the baseline formulation, achieves an ionic conductivity of 1.85 mS / cm (25℃), 89.2% capacity retention after 1000 cycles, and a tensile strength of 1.2 MPa through a reasonable ratio of BOZP and TDGE (100:40), the introduction of 10% siloxane prepolymer, optimization of the lithium salt ratio (LiTFSI:LiFSI=25:5), and a curing process. It exhibits good ion transport, electrochemical stability, cycle life, and mechanical strength, meeting the basic application requirements of button-type supercapacitors. Adjustments to each variable significantly affect performance; increasing the siloxane prepolymer content to 15% increases the mechanical strength to 1.5 MPa, and optimizing the thermal crosslinking process (90℃ / 2.5h + 125℃ / 1.5h) increases the ionic conductivity to 1.85 mS / cm (25℃). The crosslinking density was 89.8%, while the ionic conductivity, mechanical strength, and cycle performance were slightly reduced due to insufficient TDGE dosage, shortened UV curing time, and reduced DMPA dosage. Although increasing the LiFSI ratio improved the ionic conductivity to 1.92 mS / cm, the ionic conductivity dropped to 1.05 mS / cm and the cycle retention rate was only 75.3% after replacing the core monomer with PEGDMA+DPDS in Comparative Example 1. The mechanical strength dropped to 0.6 MPa and the ionic conductivity dropped to 1.23 mS / cm after removing the siloxane prepolymer in Comparative Example 2. The overall performance of both examples was far inferior to that of Example 1, highlighting the key role of the core monomer combination (BOZP+TDGE) and siloxane prepolymer in constructing a stable crosslinking network and optimizing the overall performance of the electrolyte.

[0093] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this application, and this application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this application, and these modifications and improvements are also considered to represent the scope of protection of this application.

Claims

1. A sulfide solid electrolyte, characterized in that, This includes organic-inorganic composite membranes generated from raw material systems through a curing reaction. The raw material system includes a first monomer, a second monomer, a lithium salt, a siloxane prepolymer, and an initiator, wherein the first monomer is N,N′-1,3 Propylenediol (oxazolidine) 2 (ketone), wherein the second monomer is 4,4'-thiobisphenol diglycidyl ether; The siloxane prepolymer is prepared by partial hydrolysis and condensation reaction of tetraethyl orthosilicate; the initiator includes a photoinitiator and a thermal initiator; the curing reaction is completed based on ultraviolet light irradiation pre-curing and segmented heat treatment.

2. The sulfide solid electrolyte according to claim 1, characterized in that, The mass ratio of the first monomer to the second monomer ranges from 100:30 to 100:

50.

3. The sulfide solid electrolyte according to claim 1, characterized in that, The amount of the tetraethyl orthosilicate used is 10% to 20% of the mass of the first monomer.

4. A sulfide solid electrolyte according to claim 1, characterized in that, The lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, wherein the mass of the lithium bis(trifluoromethanesulfonyl)imide is 20 to 25 parts and the mass of the lithium bis(fluorosulfonyl)imide is 5 to 10 parts.

5. A sulfide solid electrolyte according to claim 1, characterized in that, The photoinitiator is dimethyl benzoate, and the amount of dimethyl benzoate used is 1% to 1.5% of the mass of the first monomer; the thermal initiator is benzoyl peroxide.

6. A preparation method for preparing a sulfide solid electrolyte as described in any one of claims 1 to 5, characterized in that, include: The first monomer, the second monomer, the lithium salt, and the initiator were dried separately. In an inert atmosphere, tetraethyl orthosilicate, an organic solvent, and an acid catalyst are mixed and partially hydrolyzed and condensed to obtain a siloxane prepolymer. The first monomer, the second monomer, and the lithium salt, after being dried, are mixed with the siloxane prepolymer and then subjected to high-speed dispersion and ultrasonic treatment to generate a homogeneous composite premix. An initiator is added to the composite premixed liquid, and after stirring and adjusting to a preset viscosity, a film is formed on the substrate and pre-cured by ultraviolet light irradiation to obtain a semi-cured film. The semi-cured film is subjected to segmented heat treatment under vacuum and inert atmosphere to deeply crosslink the organic phase and completely cure the inorganic phase, forming a cured film with an organic-inorganic composite network. The cured film is vacuum dried to obtain the sulfide solid electrolyte.

7. The preparation method according to claim 6, characterized in that, The segmented heat treatment includes a first stage and a second stage. The first stage includes holding at 80-90℃ for 2-3 hours, and the second stage includes holding at 120-140℃ for 1-2 hours.

8. The preparation method according to claim 6, characterized in that, The UV irradiation pre-curing time is 100 to 200 seconds; and / or, the vacuum drying temperature is 60-80°C, and the vacuum drying time is 6-10 hours.

9. The preparation method according to claim 6, characterized in that, The high-speed dispersion speed is 5000-10000 rpm, the high-speed dispersion time is 30-60 minutes, and the ultrasonic treatment time is 30-60 minutes.

10. A supercapacitor, characterized in that, The invention comprises a positive electrode, a negative electrode, and a sulfide solid electrolyte as described in any one of claims 1 to 5 disposed between the positive and negative electrodes; the positive electrode comprises lithium nickel cobalt manganese oxide and activated carbon, and the negative electrode comprises activated carbon.

Images