Solid-state electrolyte membrane and method for producing the same

Abstract

The application provides a solid electrolyte membrane and a preparation method thereof. The solid electrolyte membrane comprises the following components in parts by mass: 100 parts of a polyether block polymer and 10-30 parts of a sheet inorganic filler. The polyether block polymer comprises a polyether chain segment and an ion-conducting segment containing a sulfonic acid alkali metal ion group. The polyether block polymer is obtained by graft polymerization of a functional monomer containing a sulfonic acid alkali metal ion group on an end hydroxyl polyether compound, wherein the mass ratio of the end hydroxyl polyether compound and the functional monomer containing a sulfonic acid alkali metal ion group is 1:3-6. The solid electrolyte membrane comprises an anchoring ion-conducting segment and a flexible polyether chain segment introduced in the polyether block polymer, which can construct a controllable ion migration channel, and the content of the polyether chain segment is controlled to make the solid electrolyte membrane have good film-forming property. Meanwhile, the sheet inorganic filler is added, which can induce the formation of an ordered ion migration channel. Therefore, the solid electrolyte membrane has high cation migration rate and ion conductivity.

Description

Technical Field

[0001] This application relates to the field of solid electrolyte technology, specifically to a solid electrolyte membrane and its preparation method. Background Technology

[0002] With the widespread application of lithium-ion and sodium-ion batteries in new energy vehicles, wearable devices, and energy storage systems, battery safety and energy density have gradually become core bottlenecks in research and industrialization. Solid-state electrolyte membranes, as a key material to replace traditional liquid electrolytes, are considered a crucial component for building next-generation high-safety, high-energy-density solid-state batteries due to their excellent interfacial stability, lack of leakage risk, and high electrochemical window.

[0003] Currently, common polymer-based solid electrolyte materials mainly employ physical blends of polyethylene oxide (PEO) with lithium salts (such as LiTFSI) or sodium salts (such as NaTFSI). These systems form ion migration channels through the coordination of ether oxygen with cations; however, their conductivity mechanism depends on the coordination diffusion of chain segments, leading to a decrease in cation mobility (t). + Li or t + Na The conductivity (PDO) is relatively low, typically less than 0.3%, with a high proportion of anion migration and significant polarization effects, which can easily lead to battery interface instability and limit the application of fast charge / discharge and high energy density systems. Furthermore, due to the tendency of PEO to crystallize, the ionic conductivity of solid electrolyte membranes is relatively low at room temperature, making it difficult to meet practical application requirements.

[0004] To improve lithium-ion transference number, existing technologies have attempted to construct anchored polymer electrolytes by introducing fixed anionic structures (such as sulfonic acid groups, carboxylic acid groups, etc.). In these systems, the cation is the only migrating ion, which theoretically can significantly improve the cation mobility (t). + Li or t + Na However, ion-conducting polymers such as sodium polystyrene sulfonate (PSSNa) or sodium polymethyl methacrylate sulfonate (PMASNa) are usually rigid and lack sufficient flexible chain segments for support, resulting in poor film-forming properties, low mechanical properties, and discontinuous conduction paths, making it difficult to improve the overall ionic conductivity.

[0005] Therefore, there is an urgent need to develop a solid electrolyte membrane with a reasonable structure, efficient migration mechanism, and the ability to balance film formation and ion conduction performance, in order to meet the practical application requirements of high-performance solid-state batteries. Summary of the Invention

[0006] This application provides a solid electrolyte membrane and its preparation method. The solid electrolyte membrane has high cation mobility and ionic conductivity, and can be used to prepare high energy density solid batteries.

[0007] In a first aspect, this application provides a solid electrolyte membrane comprising the following components in parts by weight: 100 parts of a polyether block polymer and 10-30 parts of a sheet-like inorganic filler, wherein the polyether block polymer comprises polyether segments and ion-conducting segments containing sulfonic acid alkali metal ion groups, and the polyether block polymer is obtained by grafting a hydroxyl-terminated polyether compound with a functional monomer containing sulfonic acid alkali metal ion groups, wherein the mass ratio of the hydroxyl-terminated polyether compound to the functional monomer containing sulfonic acid alkali metal ion groups is 1:3-6.

[0008] According to this application, the solid electrolyte membrane includes a polyether block polymer, in which anchored ion-conducting segments are introduced as the main migration channels for migrating ions. These segments are connected to flexible polyether segments through a block structure, creating a phase separation interface in the polymer system's microstructure and constructing a controllable ion migration pathway. Simultaneously, the content of the polyether segments is controlled to ensure good film-forming properties. Furthermore, sheet-like inorganic fillers are added, whose anisotropic morphology and surface polarity induce segment orientation and alignment, thereby inducing the formation of ordered ion migration pathways. Therefore, without relying on a high content of migratable anionic salts, this solid electrolyte membrane achieves high cation mobility and ionic conductivity by constructing ordered cation-selective migration channels and a flexible diffusion network.

[0009] Specifically, the polyether block polymer in the solid electrolyte membrane is composed of ion-conducting segments containing sulfonic acid alkali metal ion groups and flexible polyether segments. These two types of segments are connected through a block structure. Due to the high polarity and rigidity of the ion-conducting segments and their low compatibility with the polyether segments, this polyether block polymer exhibits microphase separation capabilities during drying or heat treatment. The ion-conducting segments provide anchored anion sites, constructing fixed cation migration pathways within the polymer backbone, effectively inhibiting anion migration behavior, thereby significantly improving cation mobility. The polyether segments, as flexible segments, participate in the construction of the phase separation structure and contribute to the overall microphase separation process. The polyether block polymer imparts segment slippage capability and film-forming properties to the system. It is obtained by grafting functional monomers containing sulfonic acid alkali metal ion groups onto a hydroxyl-terminated polyether compound. The mass ratio of the hydroxyl-terminated polyether compound to the functional monomers containing sulfonic acid alkali metal ion groups is controlled at 1:3 to 6. On the one hand, this ensures the continuity of the flexible network. On the other hand, it avoids the migration of ions and the recoordination of ether oxygen in the polyether due to excessive polyether segment content, thereby changing the cation migration mechanism of the overall system and causing the ion migration channel in the anchoring structure to shift (i.e., more cations migrate in the polyether segments), thus reducing the cation migration rate.

[0010] Building upon this, the solid electrolyte membrane also includes 10–30 parts by mass of sheet-like inorganic filler. This sheet-like inorganic filler, as is known in the art, is a two-dimensional inorganic filler. During membrane drying or heat treatment, this filler forms an oriented arrangement along the membrane surface, inducing the adsorption, extension, and directional stacking of polymer block segments on its surface. Through this interfacial induction mechanism, the ion-conducting segments rich in anchored sulfonate groups construct continuous and ordered ion migration channels perpendicular to the membrane surface. These ion migration channels are aligned with the cation migration direction, thus significantly improving the cation migration efficiency and ionic conductivity of the solid electrolyte membrane. Furthermore, the sheet-like inorganic filler can also effectively improve the mechanical strength and dimensional stability of the solid electrolyte membrane.

[0011] Therefore, by synergistically constructing an ion conduction path perpendicular to the membrane surface through the migration selectivity of the ion-conducting chain segment anchoring structure, the flexible synergistic effect of the polyether chain segment, and the orderly guiding effect of the sheet-like inorganic filler, the solid electrolyte membrane provided in this application has high cation mobility and ionic conductivity without relying on a large amount of migratory anion salt.

[0012] In some embodiments, the polyether segment comprises a polyethylene oxide segment and a polypropylene oxide segment, the polyether segment having a weight-average molecular weight of 4000 to 6000, and the polyethylene oxide segment comprising 75% to 85% by mass in the polyether segment.

[0013] In some of the above embodiments, the polyethylene oxide segments have good polar coordination ability and can form reversible coordination structures with cations to a certain extent, thereby reducing the local energy barrier during the migration of cations between the cation migration channels formed by the ion-conducting segments and helping to improve the ion migration rate. The polypropylene oxide (PPO) segments are more hydrophobic, have lower crystallinity, and higher segment flexibility, which can effectively suppress the problem of restricted segment movement caused by excessive crystallization of PEO segments in the membrane, thereby enhancing the diffusivity and structural continuity of the entire flexible network. At the same time, controlling the weight-average molecular weight of the polyether segments within the range of 4000 to 6000 helps to maintain the polymer chain in the membrane structure. The appropriate length and flexibility of the segments ensure that they have sufficient expansion capacity to participate in the construction of microphase separation interfaces, while avoiding segment entanglement, inhibition of segment migration, or reduction of overall material processability due to excessive molecular weight. By controlling the mass percentage of PEO segments in polyether segments within the range of 75% to 85%, the microscopic segment slip environment of the solid electrolyte membrane can be effectively improved while maintaining segment polarity synergy, thereby enhancing the dynamic response capability of ion channels. Therefore, the above design helps to achieve a performance balance between microscopic segment movement and macroscopic membrane structure while constructing ion conduction channels, thereby further improving the ionic conductivity and cation migration efficiency of the solid electrolyte membrane.

[0014] In some embodiments, the polyether block polymer has an ion-conducting segment-b-polyether segment-b-ion-conducting segment structure.

[0015] In some of the above embodiments, in the ion-conducting segment-b-polyether segment-b-ion-conducting segment structure, the ion-conducting segments are distributed at both ends of the polymer chain, and the polyether segment is located in the center, forming a triblock copolymer structure. This structure helps to enhance the interaction between the ion-conducting segments and form a more stable continuous conductive phase region. As rigid, highly polar structural segments, the ion-conducting segments interact more strongly in the membrane and tend to aggregate, forming continuous ion migration channels. The polyether segment distributed between the ion-conducting segments can achieve flexible connection between the conductive phases at both ends, and also participate in the construction of the phase separation interface, enhancing the integrity and flexibility of the microstructure.

[0016] Furthermore, during membrane drying or heat treatment, the ion-conducting segments in this triblock structure are more likely to align synchronously under the induction of the sheet-like inorganic filler, constructing a continuous conductive channel perpendicular to the membrane surface. This helps improve the spatial consistency of ion migration paths. Simultaneously, this structure also enhances the overall thermal and conformational stability of the block polymer, inhibiting entanglement or rearrangement of polyether segments near the interface and maintaining the continuity of the ion-conducting channels. Therefore, polyether block polymers using the aforementioned triblock structure can further optimize the conductive network configuration, improving cation migration efficiency and ionic conductivity.

[0017] In some embodiments, the ion-conducting segment includes a lithium polystyrene sulfonate segment or a sodium polystyrene sulfonate segment.

[0018] In some of the above embodiments, polystyrene sulfonate segments have a typical rigid aromatic backbone. Their main chain structure is stable and highly electronegative. In block polymer systems, they can form a significant difference in polarity and compliance with flexible polyether segments, which is beneficial for driving microphase separation behavior during film formation and constructing a clearer phase separation interface. As a result, these segments are more likely to aggregate into a continuous ion-conducting phase during phase separation, which is conducive to forming a more stable cation migration channel. At the same time, the polystyrene sulfonate structure is stably arranged in the membrane and has good chemical stability. It can provide a durable anchoring anion environment in the electrochemical system and avoid the problem of competitive migration between anions and cations during the segment migration process. Therefore, the use of polystyrene sulfonate segments can further improve the cation migration efficiency and ionic conductivity of solid electrolyte membranes.

[0019] It should also be noted that the lithium polystyrene sulfonate segment (PSSLi) uses lithium ions as the main migration component and is suitable for lithium-ion battery systems; while the sodium polystyrene sulfonate segment (PSSNa) uses sodium ions as the main migration component and is suitable for sodium-ion battery systems.

[0020] In some embodiments, the method for preparing the polyether block polymer includes the following steps:

[0021] S1: The esterification reaction of the hydroxyl-terminated polyether compound with 4-cyano-4-(phenylthiocarbamoylthio)valerate acid yields a polyether grafting chain transfer agent.

[0022] S2: A polyether grafting chain transfer agent is subjected to a free radical polymerization reaction with a functional monomer containing sulfonic acid alkali metal ion groups to obtain a polyether block polymer.

[0023] In the above embodiments, a method for preparing polyether block polymers is specifically described. In step S1, a hydroxyl-terminated polyether compound is used to undergo an esterification reaction with a RAFT-type chain transfer agent, 4-cyano-4-(phenylthiocarbamoylthio)valerate (CPADB). This can introduce the controllable polymerization active site into the polyether backbone structure, thereby enabling the polyether segment to serve as the polymerization initiation group of the RAFT initiation end, ensuring that the subsequent block polymerization reaction has good molecular weight control capability and block structure integrity.

[0024] In step S2, the functional monomer uses a monomer containing sulfonic acid alkali metal ion groups, which is polymerized with a polyether grafting chain transfer agent under RAFT control to synthesize a polyether block polymer with a well-defined structure and controllable molecular chain length.

[0025] The above preparation method can precisely construct a block polymer skeleton with flexible polyether segments and anchored ion-conducting segments at the molecular level. This can effectively ensure that the incompatibility between blocks drives the microphase separation behavior, which is conducive to the construction of a continuous cation migration channel network, thereby improving the cation migration efficiency and ionic conductivity of the solid electrolyte membrane.

[0026] In some embodiments, step S1 specifically includes: dispersing 100 parts of a hydroxyl-terminated polyether compound in 300-500 parts of dichloromethane, then adding 5-15 parts of CPADB, 4-10 parts of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide), and 2-6 parts of NHS (N-hydroxysuccinimide), and reacting at 20-30°C for 16-24 hours under a nitrogen atmosphere. After the reaction is completed, the reaction solution is washed with saturated NaHCO3 aqueous solution and distilled water, and the dichloromethane is removed by rotary evaporation to obtain the polyether grafting chain transfer agent.

[0027] In some embodiments, step S2 specifically includes: dispersing the polyether grafted chain transfer agent from step S1 in 400-600 parts of water, adding 300-600 parts of functional monomers containing sulfonic acid alkali metal ion groups, 1-3 parts of ammonium persulfate and 0.5-2 parts of sodium bisulfite, reacting at 60-70°C for 8-12 hours, and after the reaction is completed, dialysis of the reaction solution through a semi-permeable membrane to remove small molecules, and drying to obtain the polyether block polymer.

[0028] It is understandable that the choice of functional monomers does not necessarily include sulfonic acid alkali metal ion groups; it can also be sulfonic acid groups. At the end of the polymerization, the sulfonic acid groups are converted into the corresponding sulfonic acid alkali metal ion groups by neutralization using alkali metal salts or alkali metal hydroxides.

[0029] In some embodiments, the hydroxyl-terminated polyether compound comprises polyethylene oxide segments and polypropylene oxide segments, the weight-average molecular weight of the hydroxyl-terminated polyether compound is 4000-6000, and the mass percentage of the polyethylene oxide segments in the hydroxyl-terminated polyether compound is 75%-85%. Based on the above embodiments, the polyether block polymer obtained in this way helps to achieve synergistic control of segment polarity and flexibility, enhancing the coordination response to ions while maintaining the segment slippage ability, and improving the cation migration efficiency and ionic conductivity of the solid electrolyte membrane.

[0030] In some embodiments, the terminal hydroxyl polyether compound is a bi-hydroxyl polyether compound. Based on the above embodiments, it is convenient to introduce RAFT chain transfer groups at both ends, which is suitable for the construction of triblock structures, and is beneficial to improve phase separation ability and channel configuration stability, and improve the cation migration efficiency and ionic conductivity of solid electrolyte membranes. As an example, in one embodiment of this application, Pluronic F38 is used as the terminal hydroxyl polyether compound, which has a PEO-b-PPO-b-PEO block structure with a weight-average molecular weight of about 5000, wherein the mass percentage of PEO segments is about 80%.

[0031] In some embodiments, the functional monomer includes sodium styrene sulfonate. Based on the above embodiments, this monomer can form sodium styrene sulfonate segments with a rigid backbone and highly polar structure during RAFT polymerization, which is beneficial for constructing stable and highly selective cation migration channels and improving the cation migration efficiency and ionic conductivity of solid electrolyte membranes.

[0032] In some embodiments, the component also includes the following components in parts by weight: 1 to 10 parts of an organic anionic alkali metal salt, wherein the organic anionic alkali metal salt includes an organic anionic lithium salt or an organic anionic sodium salt.

[0033] In some of the above embodiments, the appropriate addition of organic anionic alkali metal salts can supplement the membrane system with a certain concentration of migratory cations without destroying the anchoring structure's dominant conduction mechanism, thereby improving the overall carrier concentration and ionic conductivity. At the same time, since the amount of organic anionic alkali metal salts added is limited to 1 to 10 parts by mass, only a small amount of cation source is provided on the basis of the selective migration channel dominant structure constructed by the ion-conducting block, without introducing an excessive amount of migratory anions. This helps to maintain a high cation mobility while improving ionic conductivity, thus enhancing ionic conductivity.

[0034] Furthermore, the inventors discovered that adding too much organic anionic alkali metal salt can lead to a simultaneous decrease in cation mobility and ionic conductivity. The possible reason is that introducing too much organic anionic alkali metal salt into the system may affect the cation channels constructed by the polyether block polymer, thus negatively impacting both cation mobility and ionic conductivity.

[0035] Understandably, organic anionic alkali metal salts preferably possess high electrolytic stability and dissociation properties, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), which can rapidly release Li into the polymer matrix. + Or Na + They migrate within the ion-conducting chain segments, thereby expanding the cation conduction pathway and improving migration efficiency.

[0036] In some embodiments, the sheet-like inorganic filler comprises an aminoated MXene material, wherein the MXene material has an average sheet diameter of 0.2–5 μm and an average thickness of 5–100 nm.

[0037] In some of the above embodiments, the aminated MXene material has a typical two-dimensional sheet structure and a high specific surface area. During the solid electrolyte membrane formation process, it is easy to spontaneously align in the membrane surface direction to construct a multilayer stacked structure. Its surface contains amino groups, which can form hydrogen bonds or electrostatic interactions with ion-conducting segments (such as sulfonate segments) in the polymer, thereby inducing the ion-conducting segments to extend and stack on the MXene surface in a directional manner, constructing an ordered ion migration channel along the direction perpendicular to the membrane surface. This junction helps to improve the directional consistency of the conduction path and significantly reduce the spatial resistance in the ion migration path.

[0038] In addition, the amino groups on the surface of the aminated MXene material can also adsorb free anions (such as TFSI-) in the added organic anionic salt, inhibit their migration behavior, and further enhance the selective migration efficiency of cations, thereby improving ionic conductivity while maintaining high cation mobility.

[0039] Compared to other sheet-like inorganic materials (such as bentonite, layered double hydroxides, and graphite oxides), MXene materials exhibit superior performance in terms of size control, interfacial compatibility, and functional modification capabilities. They can induce segment alignment, construct vertical conductive channels spanning the film thickness, and enhance the mechanical strength and dimensional stability of composite membranes through structural regulation. Therefore, aminated MXene is more suitable as a sheet-like filler for constructing solid electrolyte membranes with high ionic conductivity and cation mobility. In some embodiments, aminated MXene materials are prepared by modifying MXene materials with aminated silane coupling agents.

[0040] In some embodiments, the aminated MXene material is prepared by the following method: 10 parts of MXene material are ultrasonically dispersed in 100-200 parts of an aqueous ethanol solution, 3-10 parts of an aminosilane coupling agent are added, the pH is adjusted to 4.5-5.5, the mixture is stirred at 20-30°C for 24-48 hours, and the mixture is centrifuged, washed and dried to obtain the aminated MXene material.

[0041] As an example, in one embodiment of this application, a titanium carbide-type MXene material (Ti3C2T) with an average flake diameter of 2 μm and an average thickness of 80 nm is used. x ); 3-aminopropyltrimethoxysilane was used as the silane coupling agent.

[0042] Secondly, this application provides a method for preparing a solid electrolyte membrane, comprising:

[0043] The components of the solid electrolyte according to any embodiment of the first aspect are dispersed in a solvent to obtain a slurry; the slurry is cast and dried to obtain a solid electrolyte membrane.

[0044] According to this application, the preparation method involves dispersing the components of the solid electrolyte described in any embodiment of the first aspect in a solvent to obtain a slurry. In this slurry, the polyether block polymer is the dominant film-forming component, exhibiting good solubility and flexible segment flowability, which contributes to the spreadability and film continuity of the slurry during the casting process.

[0045] The slurry is cast into a wet film using methods such as blade coating or roller coating. During subsequent drying or heat treatment, the polymer undergoes microphase separation to construct ion-conducting channels. Sheet-like fillers align and align on the film surface, inducing segment stacking. Organic anionic salts release migratable cations to participate in the migration network, ultimately forming a solid electrolyte membrane with ordered ion migration channels. This method, without relying on high temperatures or complex crosslinking systems, allows for the directional assembly of material structures under conventional solvent treatment conditions. It features strong process controllability and high adaptability, making it suitable for preparing electrolyte membranes in high-performance lithium-ion or sodium-ion solid-state batteries.

[0046] In some embodiments, the solvent is N,N-dimethylformamide.

[0047] In some embodiments, the solid content of the slurry is 8% to 15%.

[0048] In some embodiments, the process of casting and drying the slurry to obtain a solid electrolyte membrane specifically includes: casting the slurry onto a glass substrate by means of a scraping method, controlling the wet film thickness to be 80-150 μm, and drying it at 60-80°C for 3-5 hours to obtain a solid electrolyte membrane.

[0049] In some embodiments, after drying, the solid electrolyte membrane is further hot-pressed at 100–120°C and 2–5 MPa for 15–30 min to obtain the solid electrolyte membrane. Based on the above embodiments, the further hot-pressing treatment after drying can not only further compact the membrane structure, improve its density and dimensional stability, but also promote the reconfiguration of polymer chain segments, enhance the continuity and directional consistency of ion migration paths, and improve the adhesion between the membrane and the electrode interface, thereby improving the overall electrical performance of the solid electrolyte membrane.

[0050] Thirdly, this application also provides a solid-state battery, comprising: a solid electrolyte membrane prepared according to any embodiment of the first aspect or a solid electrolyte membrane prepared according to any embodiment of the second aspect.

[0051] According to this application, the solid-state battery, by using the solid electrolyte membrane described in any embodiment of the first aspect or the solid electrolyte membrane prepared by the method described in any embodiment of the second aspect, can construct an electrolyte layer with high cation mobility and high ionic conductivity without relying on a high content of migratory anion salt, thereby obtaining a solid-state battery with good electrical performance.

[0052] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0053] 1. By constructing a block polymer structure of polyether segments and ion-conducting segments, the synergistic construction of cation migration channels and flexible networks driven by microphase separation is achieved, which effectively improves the cation mobility and ionic conductivity of solid electrolyte membranes without relying on high content of migratory anionic salts.

[0054] 2. By controlling the content and molecular structure of polyether segments, the membrane can have good segment slippage ability and film-forming properties, thereby improving the material's processing adaptability and dimensional stability.

[0055] 3. By introducing sheet-like inorganic fillers, the ion-conducting chain segments are induced to oriented vertically within the membrane, constructing an ordered ion migration channel that spans the membrane thickness, further reducing polarization resistance and improving ion migration efficiency and directional consistency.

[0056] 4. A small amount of highly stable organic anion lithium / sodium salt can be added to adjust the carrier concentration, further enhancing the ion conduction ability while maintaining high cation mobility, and achieving synergistic optimization of mobility and conductivity. Detailed Implementation

[0057] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0061] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0062] The following examples illustrate specific implementation methods of this application using a solid electrolyte membrane for sodium-ion batteries.

[0063] Pluronic F38 has a PEO-b-PPO-b-PEO block structure with a weight-average molecular weight of approximately 5000, of which the mass percentage of PEO segments is approximately 80%.

[0064] MXene material, a titanium carbide-type MXene material with an average flake diameter of 2μm and an average thickness of 80nm.

[0065] The silica particles have an average particle size of 500 nm.

[0066] Preparation Example 1

[0067] Preparation of polyether block polymers:

[0068] 100 parts of Pluronic F38 were dispersed in 400 parts of dichloromethane, and then 12.2 parts of CPADB, 8.4 parts of EDC, and 5.1 parts of NHS were added to the above system. The reaction was carried out under nitrogen atmosphere at 25°C for 18 hours. After the reaction was completed, the reaction solution was washed three times with saturated NaHCO3 aqueous solution and water, respectively. The washed reaction solution was dried by rotary evaporation to remove dichloromethane and obtain polyether grafted chain transfer agent.

[0069] Add 500 parts of water to the above-mentioned polyether grafting chain transfer agent, then add 450 parts of sodium styrene sulfonate, 2 parts of ammonium persulfate and 1.2 parts of sodium bisulfite. After deoxygenation treatment, stir and react at 65°C for 10 hours under a nitrogen atmosphere. After the reaction is completed, the reaction solution is dialyzed in water through a semi-permeable membrane with a cutoff of 5000 for 48 hours, with the water changed every 12 hours to remove small molecule impurities. After drying, polyether block polymer A is obtained.

[0070] Preparation Example 2

[0071] Preparation of polyether block polymers:

[0072] The preparation method was largely the same as in Example 1, except that a hydroxyl-terminated polyethylene glycol with a weight-average molecular weight of 5000 was used instead of Pluronic F38 to finally obtain polyether block polymer B.

[0073] Preparation Example 3

[0074] Preparation of polyether block polymers:

[0075] 100 parts of hydroxyl-terminated polyethylene glycol with a weight average molecular weight of 5000 were dispersed in 400 parts of dichloromethane. Then, 6.1 parts of CPADB, 4.2 parts of EDC, and 2.55 parts of NHS were added to the above system. The mixture was stirred at 25°C for 18 hours under a nitrogen atmosphere. After the reaction was completed, the reaction solution was washed three times with saturated NaHCO3 aqueous solution and water, respectively. The washed reaction solution was then dried by rotary evaporation to remove dichloromethane, thus obtaining a polyether grafted chain transfer agent.

[0076] Add 500 parts of water to the above-mentioned polyether grafted chain transfer agent, then add 450 parts of sodium styrene sulfonate, 2 parts of ammonium persulfate and 1.2 parts of sodium bisulfite. After deoxygenation treatment, stir and react at 65°C for 12 hours under a nitrogen atmosphere. After the reaction is completed, the reaction solution is dialyzed in water through a semi-permeable membrane with a cutoff of 5000 for 48 hours. The water is changed every 12 hours to remove small molecule impurities. After drying, polyether block polymer C is obtained.

[0077] Preparation Example 4

[0078] Preparation of polyether block polymers:

[0079] The preparation method is largely the same as in Example 1, except that sodium methacrylate is used instead of sodium styrene sulfonate to finally obtain polyether block polymer D.

[0080] Comparative Preparation Example 1

[0081] Preparation of polyether block polymers:

[0082] 100 parts of Pluronic F38 were dispersed in 400 parts of dichloromethane, and then 12.2 parts of CPADB, 8.4 parts of EDC, and 5.1 parts of NHS were added to the above system. The reaction was carried out under nitrogen atmosphere at 25°C for 18 hours. After the reaction was completed, the reaction solution was washed three times with saturated NaHCO3 aqueous solution and water, respectively. The washed reaction solution was dried by rotary evaporation to remove dichloromethane and obtain polyether grafted chain transfer agent.

[0083] Add 500 parts of water to the above-mentioned polyether grafted chain transfer agent, then add 200 parts of sodium styrene sulfonate, 2 parts of ammonium persulfate and 1.2 parts of sodium bisulfite. After deoxygenation treatment, stir and react at 65°C for 8 hours under a nitrogen atmosphere. After the reaction is completed, the reaction solution is dialyzed in water through a semi-permeable membrane with a cutoff of 5000 for 48 hours. The water is changed every 12 hours to remove small molecule impurities. After drying, polyether block polymer E is obtained.

[0084] Preparation Example 5

[0085] Preparation of amination-modified MXene materials:

[0086] Ten parts of MXene material were ultrasonically dispersed in 150 parts of ethanol aqueous solution (volume ratio 1:1), and 8 parts of 3-aminopropyltrimethoxysilane were added. The pH was adjusted to 5, and the mixture was stirred at 25°C for 24 hours. After centrifugation and washing, the mixture was vacuum dried at 60°C to obtain the aminated MXene material.

[0087] Comparative Preparation Example 2

[0088] Preparation of aminated silica particles:

[0089] Ten parts of silica particles were ultrasonically dispersed in 150 parts of ethanol aqueous solution (volume ratio 1:1), and eight parts of 3-aminopropyltrimethoxysilane were added. The pH was adjusted to 5, and the mixture was stirred at 25°C for 24 hours. After centrifugation and washing, the mixture was vacuum dried at 60°C to obtain aminated silica particles.

[0090] Example 1

[0091] Preparation of solid electrolyte membranes:

[0092] 100 parts of polyether block polymer A, 20 parts of aminated MXene material and 5 parts of NaTFSI were added to N,N-dimethylformamide. After stirring and mixing, appropriate amount of N,N-dimethylformamide was added to obtain a slurry with a solid content of 10%. The slurry was cast onto a glass substrate by a scraper, and the thickness of the wet film was controlled to be 100 μm. The wet film and the glass substrate were then dried at 70 °C for 4 h to remove the solvent. After drying, the film was hot-pressed at 110 °C and 4 MPa for 20 min to obtain a solid electrolyte membrane.

[0093] Example 2

[0094] Preparation of solid electrolyte membranes:

[0095] Similar to Example 1, except that polyether block polymer B is used instead of polyether block polymer A.

[0096] Example 3

[0097] Preparation of solid electrolyte membranes:

[0098] Similar to Example 1, except that polyether block polymer C is used instead of polyether block polymer A.

[0099] Example 4

[0100] Preparation of solid electrolyte membranes:

[0101] Similar to Example 1, except that polyether block polymer D is used instead of polyether block polymer A.

[0102] Example 5

[0103] Preparation of solid electrolyte membranes:

[0104] Similar to Example 1, except that unmodified MXene material is used instead of aminated MXene material.

[0105] Example 6

[0106] Preparation of solid electrolyte membranes:

[0107] It is largely the same as Example 1, except that NaTFSI is not added.

[0108] Example 7

[0109] Preparation of solid electrolyte membranes:

[0110] It is largely the same as Example 1, except that 10 parts of NaTFSI are added.

[0111] Example 8

[0112] Preparation of solid electrolyte membranes:

[0113] It is largely the same as Example 1, except that 15 parts of NaTFSI are added.

[0114] Comparative Example 1

[0115] Preparation of solid electrolyte membranes:

[0116] Similar to Example 1, except that polyether block polymer E is used instead of polyether block polymer A.

[0117] Comparative Example 2

[0118] Preparation of solid electrolyte membranes:

[0119] Similar to Example 1, except that aminated silica particles are used instead of aminated MXene material.

[0120] Comparative Example 3

[0121] Preparation of solid electrolyte membranes:

[0122] Similar to Example 3, except that aminated silica particles are used instead of aminated MXene material.

[0123] Test section

[0124] Sodium ion mobility t + Na Testing: A symmetrical cell (Na|solid electrolyte membrane under test|Na) was assembled using the Bruce-Vincent method and performed at 25°C. A constant bias voltage of 10mV was applied, and the initial instantaneous current I0 and steady-state current I were measured. ss The interfacial resistances R0 and R2 before and after polarization were obtained by combining electrochemical impedance spectroscopy. ss Calculate t according to the following formula + Na .

[0125]

[0126] Ionic conductivity testing: A symmetrical battery (stainless steel | solid electrolyte membrane under test | stainless steel) was assembled and tested at 25°C on an electrochemical workstation at 10°C. -1 ~10 6 The solid electrolyte membrane resistance Rm was obtained by testing within a frequency range of Hz, and the ionic conductivity σ (unit: mS / cm) was calculated according to the following formula.

[0127]

[0128] Where Rm is the equivalent resistance, L is the thickness of the solid electrolyte membrane under test, and S is the electrode area.

[0129] The solid electrolyte membranes obtained in each embodiment and comparative example were subjected to sodium ion mobility and ionic conductivity tests, and the results are shown in Table 1.

[0130] Table 1

[0131] <![CDATA[t + Na ]]> σ(mS / cm) Example 1 0.89 0.54 Example 2 0.82 0.50 Example 3 0.78 0.41 Example 4 0.79 0.43 Example 5 0.80 0.45 Example 6 0.93 0.48 Example 7 0.85 0.52 Example 8 0.78 0.43 Comparative Example 1 0.61 0.28 Comparative Example 2 0.73 0.36 Comparative Example 3 0.58 0.22

[0132] As shown in Table 1, the sodium ion mobility and ionic conductivity of the solid electrolyte membranes obtained in each embodiment are significantly higher than those in the comparative embodiments, indicating that the solid electrolyte membranes provided in this application have high cation mobility and ionic conductivity and can be used to prepare high-performance solid batteries. The possible reasons are as follows: In Comparative Example 1, the polyether block polymer has an excessively high content of polyether segments, which affects the continuity of the cation migration channels constructed by the ion-conducting segments and also causes some cations to migrate within the polyether segments, resulting in low cation mobility and ionic conductivity of the solid electrolyte membrane. In Comparative Example 2, aminated silica is used as a filler. This filler does not oriented and distribute along the membrane surface during membrane drying or heat treatment, which affects the continuity of the cation migration channels and the transport path, and also causes some cations to migrate within the polyether segments, resulting in low cation mobility and ionic conductivity of the solid electrolyte membrane. In Comparative Example 3, a diblock polyether block polymer and aminated silica are used as fillers, and both cation mobility and ionic conductivity are significantly reduced, indicating that the diblock polyether block polymer and the spherical filler do not easily form continuous cation transport channels, resulting in poor performance of the obtained solid electrolyte membrane.

[0133] As shown in Examples 1-3, the composition of polyether segments in the polyether block polymer has a certain influence on the cation mobility and ionic conductivity of the solid electrolyte membrane. Comparing Examples 1 and 2, it can be seen that when the polyether segments include a certain proportion of polyethylene oxide segments and polypropylene oxide segments, the cation mobility and ionic conductivity of the solid electrolyte membrane are higher. Comparing Examples 2 and 3, it can be seen that when a polyether block polymer with an ion-conducting segment-b-polyether segment-b-ion-conducting segment structure is used, the cation mobility and ionic conductivity of the solid electrolyte membrane are higher.

[0134] As can be seen from Examples 1 and 4, the structure of the ion-conducting segments in the polyether block polymer has a certain influence on the cation mobility and ionic conductivity of the solid electrolyte membrane. When polystyrene sulfonate is used as the ion-conducting segment, the cation mobility and ionic conductivity of the solid electrolyte membrane are higher.

[0135] As can be seen from Examples 1 and 5, the selection of sheet-like inorganic fillers has a certain impact on the cation mobility and ionic conductivity of solid electrolyte membranes. When aminated MXene materials are used, the cation mobility and ionic conductivity of solid electrolyte membranes are higher.

[0136] As can be seen from Examples 1, 6-8, whether or not an organic anionic alkali metal salt is added to the system and the amount added have a certain impact on the cation mobility and ionic conductivity of the solid electrolyte membrane. When 1-10 parts by mass of organic anionic alkali metal salt are added, the cation mobility and ionic conductivity of the solid electrolyte membrane are higher.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A solid-state electrolyte membrane, characterized by, Components comprising the following mass parts: 100 parts of a polyether block polymer comprising a polyether chain segment and an ion-conducting chain segment containing a sulfonic acid alkali ion group, and 10-30 parts of a sheet-shaped inorganic filler, the polyether block polymer being obtained by graft polymerization of a functional monomer containing a sulfonic acid alkali ion group on a terminal hydroxyl polyether compound, wherein the mass ratio of the terminal hydroxyl polyether compound and the functional monomer containing a sulfonic acid alkali ion group is 1:3-6; The polyether block polymer has an ion-conducting chain segment-b-polyether chain segment-b-ion-conducting chain segment structure; the ion-conducting chain segment comprises a lithium polystyrene sulfonate chain segment or a sodium polystyrene sulfonate chain segment; The sheet-shaped inorganic filler comprises an aminated MXene material.

2. The solid-state electrolyte film of claim 1, wherein, The polyether chain segment comprises a polyethylene oxide chain segment and a polypropylene oxide chain segment, the weight average molecular weight of the polyether chain segment is 4000-6000, and the mass percentage content of the polyethylene oxide chain segment in the polyether chain segment is 75%-85%.

3. The solid-state electrolyte film of claim 1, wherein, The preparation method of the polyether block polymer comprises the following steps: S1: esterification reaction of a terminal hydroxyl polyether compound with 4-cyano-4-(phenylthioformylthio) pentanoic acid to obtain a polyether grafted chain transfer agent; S2: free radical polymerization reaction of the polyether grafted chain transfer agent with a functional monomer containing a sulfonic acid alkali ion group to obtain a polyether block polymer.

4. The solid-state electrolyte film of claim 3, wherein, The preparation method of the polyether block polymer satisfies at least one of the following conditions: 1) The terminal hydroxyl polyether compound comprises a polyethylene oxide chain segment and a polypropylene oxide chain segment, the weight average molecular weight of the terminal hydroxyl polyether compound is 4000-6000, and the mass percentage content of the polyethylene oxide chain segment in the terminal hydroxyl polyether compound is 75%-85%; 2) The terminal hydroxyl polyether compound is a double-end hydroxyl polyether compound; 3) The functional monomer comprises sodium styrene sulfonate.

5. The solid-state electrolyte film of claim 1, wherein, Components comprising the following mass parts are also included: 1-10 parts of an organic anion alkali metal salt, the organic anion alkali metal salt comprising an organic anion lithium salt or an organic anion sodium salt.

6. The solid-state electrolyte film according to any one of claims 1 to 5, wherein The average flake diameter of the MXene material is 0.2-5 μm, and the average thickness is 5-100 nm.

7. A method of preparing a solid-state electrolyte membrane, characterized by, Comprising: dispersing the components of the solid-state electrolyte according to any one of claims 1-6 in a solvent to obtain a slurry; casting and drying the slurry to obtain a solid-state electrolyte membrane.

8. A solid state battery, characterized by Comprising: the solid-state electrolyte membrane according to any one of claims 1-6 or the solid-state electrolyte membrane prepared by the method according to claim 7.

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