Halide composite solid-state electrolyte, method of making same, positive electrode sheet, and battery
By combining a porous SiO2 framework with a halide solid electrolyte, a continuous interconnected channel and a stable interface layer are formed, which solves the hydrolysis problem of halide electrolytes in humid environments and achieves a balance between high ionic conductivity and air stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG INTELLIGENT TRANSPORTATION TECHNOLOGY INNOVATION CENTER
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-12
AI Technical Summary
Existing halide solid electrolytes are extremely sensitive to moisture in the air and are prone to hydrolysis, which leads to structural damage and decreased ionic conductivity, thus affecting their commercial application.
A porous SiO2 framework is combined with a halide solid electrolyte. The pore structure is filled in situ to form a continuous and interconnected ion transport path and a stable transition layer is formed at the interface. Water molecules are captured by Si-O bonds to inhibit hydrolysis.
It improves the air stability and ionic conductivity of halide solid electrolytes, ensuring that the ionic conductivity retention rate is ≥85% in humid environments, meeting the application requirements of solid-state batteries.
Smart Images
Figure CN121618033B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solid-state batteries, and more particularly to a halide composite solid electrolyte and its preparation method, positive electrode, and battery. Background Technology
[0002] Solid-state batteries are considered a key direction for the next generation of energy storage technology due to their higher safety and energy density. Among them, halide solid electrolytes (such as Li3YCl6 and Li3InCl) have attracted much attention due to their high ionic conductivity, excellent oxidation stability, and good compatibility with high-voltage cathode materials. However, most halide electrolytes are extremely sensitive to moisture in the air. Exposure to humid air easily leads to hydrolysis, resulting in material structure damage, a sharp drop in ionic conductivity, and the potential generation of corrosive byproducts (such as HCl). This inherent air instability severely hinders their large-scale production, storage, and battery assembly processes, becoming a major bottleneck for their commercialization.
[0003] To improve the air stability of electrolytes, the industry has explored various strategies. One mainstream approach is surface coating, such as coating the halide particles with a hydrophobic layer to isolate them from moisture. However, the coating may increase interfacial impedance, and the integrity of the coating is difficult to guarantee during long-term cycling. Another approach is elemental doping modification, such as incorporating oxygen into halide electrolytes to enhance air stability. However, while direct bulk oxygen doping of halides may improve stability, it often comes at the cost of sacrificing some ionic conductivity.
[0004] Therefore, developing a novel halide solid electrolyte material that combines excellent air stability and high ionic conductivity is of significant practical importance and industrial value. Summary of the Invention
[0005] This application provides a halide composite solid electrolyte and its preparation method, positive electrode, and battery, which combine air stability and high ionic conductivity.
[0006] In a first aspect, this application provides a halide composite solid electrolyte, comprising: a porous SiO2 framework and a halide solid electrolyte, wherein the porous SiO2 framework has a continuous and interconnected pore structure, and the halide solid electrolyte partially fills the pore structure of the porous SiO2 framework by in-situ growth, and partially wraps the surface of the porous SiO2 framework by in-situ growth.
[0007] The interface between the porous SiO2 framework and the halide solid electrolyte includes a transition layer.
[0008] Based on a halide composite solid electrolyte, the porous SiO2 framework has a mass content of 1 wt% to 30 wt%.
[0009] The specific surface area of the porous SiO2 framework is 50-500 m². 2 / g.
[0010] Furthermore, the average pore size of the porous SiO2 framework is 5-50 nm.
[0011] Furthermore, the particle size Dv50 of the porous SiO2 framework is 0.2μm~0.7μm.
[0012] Furthermore, the mass content of the porous SiO2 framework is 5wt% to 10wt%.
[0013] Furthermore, the porous SiO2 framework is a hydrophobic SiO2 modified with alkyl chains.
[0014] Furthermore, the chemical formula of the halide solid electrolyte is Li a M x X y Where X is selected from one or more of chlorine, bromine, and iodine, M is selected from one or more of Y, In, Sc, Al, Zr, Hf, and Ta, and the values of a, x, and y satisfy the stoichiometric coefficients for valence equilibrium.
[0015] Furthermore, after being exposed to 30% humidity for 24 hours, the halide composite solid electrolyte exhibits an ionic conductivity ≥0.78 mS / cm and a retention rate of ≥85% for its ionic conductivity.
[0016] Secondly, this application provides a method for preparing the halide composite solid electrolyte according to any one of the first aspects, comprising the following steps:
[0017] The raw materials of the halide solid electrolyte are dissolved in an aprotic solvent to prepare a precursor solution;
[0018] The porous SiO2 framework is immersed in the precursor solution, and after the impregnation treatment, it is dried to obtain the impregnated material.
[0019] The impregnating material is subjected to heat treatment at a temperature of 200℃ to 500℃ for a time of 1 to 10 hours, so that the precursor reacts and crystallizes in situ within the pores of the porous SiO2 framework to obtain a halide composite solid electrolyte.
[0020] Thirdly, this application provides a positive electrode sheet, the positive electrode sheet comprising a current collector, a positive electrode active material, and a halide composite solid electrolyte as described in any one of the first aspects.
[0021] Fourthly, this application provides a battery comprising the positive electrode, negative electrode, and solid electrolyte described in the third aspect.
[0022] This application provides a halide composite solid electrolyte, its preparation method, a positive electrode, and a battery. The solid electrolyte comprises a porous SiO2 framework and a halide solid electrolyte. The porous SiO2 framework has a continuous, interconnected pore structure. Part of the halide solid electrolyte fills the pore structure of the porous SiO2 framework through in-situ growth, and part of it is grown in-situ and coated onto the surface of the porous SiO2 framework. The interface between the porous SiO2 framework and the halide solid electrolyte includes a transition layer. Based on the halide composite solid electrolyte, the mass content of the porous SiO2 framework is 1 wt% to 30 wt%; the specific surface area of the porous SiO2 framework is 50-500 m² / g. 2 / g. The continuous interconnected pore structure of the porous SiO2 framework effectively reduces the direct contact area between the halide electrolyte and ambient moisture within the pores, delaying the diffusion and penetration of moisture into the material interior. The high-bond-energy Si-O bonds also preferentially capture water molecules, inhibiting the hydrolysis of M-Cl bonds in the halides. The Si-O bonds on the surface of the porous SiO2 framework form a stable transition layer at the interface with the halide solid electrolyte, further "anchoring" the halide structure and suppressing hydrolysis reactions initiating at the interface. Furthermore, the halide electrolyte forms continuous ion transport pathways within the continuous pores of the porous SiO2, ensuring high ion conductivity on a macroscopic scale. Attached Figure Description
[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0024] Figure 1 This is a cross-sectional structural diagram of a halide composite solid electrolyte provided in this application.
[0025] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation
[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.
[0028] Halogen solid electrolytes have become a research hotspot due to their advantages such as high ionic conductivity and strong oxidation resistance. However, their extreme sensitivity to air humidity severely restricts their practical application. For example, in humid air, halide electrolytes will rapidly hydrolyze to generate corrosive gases such as HCl, leading to material structure damage, a sharp drop in ionic conductivity, and potentially causing battery safety hazards.
[0029] Currently, to improve the air stability of halide solid electrolytes, one approach is to coat the surface of the halide solid electrolyte particles with hydrophobic materials to form a physical barrier layer that prevents moisture contact. For example, a sol-gel method can be used to deposit a silicon oxide or fluoride coating on the particle surface, or a dense coating layer can be formed through chemical vapor deposition (CVD). While surface coating techniques can provide short-term moisture isolation, they may introduce interfacial impedance, and the coating layer is prone to failure. Another approach is to synthesize oxygen-doped halide solid electrolytes using high-temperature solid-state methods or solvothermal methods; however, bulk doping may disrupt the halide lattice structure, leading to a significant decrease in ionic conductivity.
[0030] In view of this, this application utilizes the through-pore structure of the porous SiO2 framework to grow the halide phase electrolyte in situ within the pores. This achieves physical isolation by reducing the contact area between the halide and moisture through the framework, without affecting the ionic conductivity. The high bond energy Si-O bonds on the SiO2 surface preferentially capture water molecules, inhibiting the hydrolysis of M-Cl bonds in the halide, and further improving air stability.
[0031] Figure 1 This is a schematic cross-sectional view of a halide composite solid electrolyte provided in this application. Figure 1 This is merely a structural illustration, such as Figure 1 As shown, the porous SiO2 framework (gray area in the figure) has a continuous and interconnected pore structure. The halide solid electrolyte (black area in the figure) partially fills the pore structure of the porous SiO2 framework through in-situ growth, and partially wraps the surface of the porous SiO2 framework through in-situ growth.
[0032] The continuous interconnected pore structure of the porous SiO2 framework can effectively reduce the direct contact area between the halide electrolyte and the ambient moisture in the pores, delay the diffusion and penetration of moisture into the material interior, and delay the triggering of hydrolysis reaction by physically blocking the halide electrolyte.
[0033] The surface of SiO2 contains high-energy Si-O bonds, which have a much higher chemical stability than the easily hydrolyzed M-Cl bonds in halides. The SiO2 framework provides a stable chemical environment for the entire composite material system. The high-energy Si-O bonds can also preferentially capture water molecules, inhibiting the hydrolysis of M-Cl bonds in halides.
[0034] The Si-O bonds on the porous SiO2 framework surface form a stable transition layer at the interface with the halide solid electrolyte, further "anchoring" the halide structure. This transition layer includes Si-O-metal bonds. Normally, water molecule penetration is relatively rapid at the interface due to capillary action. However, the presence of this transition layer inhibits hydrolysis reactions initiating at the interface, which is fundamentally different from simple physical mixing or surface coating. This transition layer is also known as the interfacial reaction layer, the chemically bonded interfacial phase, or the chemically bound layer.
[0035] The air stability of the halide-fixed electrolyte is improved through the synergistic effect of the above three functions: physical barrier, preferential capture of water molecules by Si-O bonds, and inhibition of hydrolysis at the interface by the transition layer.
[0036] In addition, the halide electrolyte forms a continuous ion transport path within the continuous channels of porous SiO2, ensuring high ion conductivity on a macroscopic scale.
[0037] This application does not limit whether all the pores in the porous SiO2 framework are completely filled.
[0038] Based on halide composite solid electrolytes, the mass content of the porous SiO2 framework ranges from 1 wt% to 30 wt%, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or any combination thereof. Adding a porous SiO2 framework with a mass content greater than 1 wt% is beneficial for improving the retention of ionic conductivity of the halide electrolyte under humid air; adding a porous SiO2 framework with a mass content less than 30% is beneficial for maintaining the high ionic conductivity of the halide electrolyte.
[0039] The specific surface area of the porous SiO2 framework is 50-500 m². 2 / g. For example, 50m 2 / g, 100m 2 / g、200m 2 / g、300m 2 / g、400m 2 / g、500m 2 / g, or any combination of the above. Specific surface area greater than 50m². 2 / g, to ensure sufficient continuous and interconnected porous structure for storing halide electrolytes, which is beneficial for improving air stability. The specific surface area of the porous SiO2 framework is less than 500m². 2 / g, which helps to improve air stability by physically blocking moisture penetration.
[0040] In addition, the high rigidity of porous SiO2 can promote pressure redistribution to achieve uniform densification and enhance interparticle contact.
[0041] Preferably, the porous SiO2 framework has a mass content of 5 wt% to 10 wt%. Within this mass content range, both air stability and ionic conductivity are maintained at a high level. Specifically, after exposure at 30% humidity for 24 hours, the halide composite solid electrolyte within this range exhibits an ionic conductivity ≥0.78 mS / cm, with a retention rate of ≥85% for ionic conductivity.
[0042] In some embodiments, the average pore size of the porous SiO2 framework is 5-50 nm. For example, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, or any combination thereof.
[0043] In some embodiments, the particle size Dv50 of the porous SiO2 framework is 0.2 μm to 0.7 μm; for example, 0.2 μm, 0.3 μm, 0.5 μm, 0.6 μm, 0.7 μm, or any combination of the above.
[0044] In some embodiments, the porous SiO2 framework is a hydrophobic SiO2 modified with alkyl chains. Specifically, methyltriethoxysilane, dodecyltriethoxysilane, or allyltriethoxysilane can be selected for modification. The specific modification method is the same as conventional modification methods and will not be described in detail. After modification, the porous SiO2 framework has hydrophobic groups on its surface, which further hinders the penetration of water molecules and improves air stability.
[0045] In some embodiments, the halide solid electrolyte is a lithium-based halide with the chemical formula Li. a M x X y Wherein, X is selected from one or more of chlorine, bromine, and iodine, and M is selected from one or more of Y, In, Sc, Al, Zr, Hf, and Ta. The values of a, x, and y satisfy the stoichiometric coefficients for valence equilibrium. Preferably, the halide solid electrolyte is Li3YCl6, Li3InCl6, or Li2ZrCl6, which have high ionic conductivity.
[0046] This application also provides a method for preparing a halide solid electrolyte, the method comprising the following steps:
[0047] Step 1: Dissolve the raw materials of the halide solid electrolyte in an aprotic solvent to prepare a precursor solution.
[0048] Step 2: Immerse the porous SiO2 framework in the precursor solution, and after the impregnation treatment, dry it to obtain the impregnated material.
[0049] Step 3: Heat-treat the impregnating material at a temperature of 200℃~500℃ for 1~10h to allow the precursor to react and crystallize in situ within the pores of the porous SiO2 framework, thereby obtaining a halide composite solid electrolyte.
[0050] In step 2, solution impregnation achieves uniform distribution of the halide precursor within the porous framework, laying the foundation for a continuous ion transport pathway in subsequent heat treatment. The drying process removes the solvent and can be performed under an inert atmosphere (such as argon). Vacuum-assisted impregnation can be used to improve impregnation efficiency.
[0051] In step 3, heat treatment promotes in-situ crystallization of the halide precursor, forming a composite structure that is tightly bound to the porous framework.
[0052] The process flow is adapted to large-scale production, requiring no complex equipment (such as vacuum coating machines or high-temperature sintering furnaces), and can flexibly balance the requirements of air stability and ionic conductivity.
[0053] Porous SiO2 can be prepared using either the template method or the sol-gel method.
[0054] The basic principle of template-based preparation of porous SiO2 is to utilize a template agent to self-assemble into an ordered structure, then introduce a silicon source (such as TEOS) and combine it with the template, and finally remove the template, leaving SiO2 with an ordered porous structure. First, the template agent (such as CTAB or P123) dissolves in a solvent to form a micelle structure; these micelles provide channels as the template. Based on this, a silicon source is added, typically hydrolyzed and polycondensed under acidic or alkaline conditions, forming a Si-O-Si network that gradually fills the pores of the template. After the reaction is complete, the template is removed by high-temperature calcination or solvent extraction, leaving a porous SiO2 structure with a high specific surface area and tunable pore size.
[0055] The sol-gel method is a chemical synthesis approach that forms a Si-O-Si network through hydrolysis and condensation reactions, suitable for preparing porous SiO2. First, a silicon source (such as TEOS) is mixed with a solvent (such as ethanol), and an acid or base catalyst is added to induce hydrolysis of the silicon source, forming a sol. As the reaction proceeds, the sol gradually transforms into a gel state and undergoes aging over a certain period, enhancing its structural stability. After gel formation, the solvent is removed by drying; conventional drying or supercritical drying methods can be used to form aerogels or bulk materials. Finally, calcination removes organic residues and improves the density and thermal stability of the SiO2 framework.
[0056] This application also provides a positive electrode sheet, which includes a current collector and a positive electrode active material, as well as a halide composite solid electrolyte of any of the above.
[0057] The positive electrode also includes a conductive agent and a binder.
[0058] For example, the above-mentioned positive electrode active material, conductive agent, binder, etc. are not specifically limited, and can be the raw materials used in the preparation of conventional solid-state batteries. For example, the positive electrode active material can be at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganese oxide, lithium-rich manganese-based material, etc. The binder can include one or more of PVDF (polyvinylidene fluoride), CMC (carboxymethyl cellulose), SBR (styrene-butadiene rubber), PAA (polyacrylic acid), HNBR (hydrogenated nitrile butadiene rubber), HNR (natural rubber), SA (sodium polyacrylate), PTFE (polytetrafluoroethylene), etc. The conductive agent can include one or more of carbon nanotubes, carbon nanofibers, VGCF (vapor-grown carbon fiber), CB (conductive carbon black), Ketjen black, graphene, graphyne.
[0059] In a specific implementation, a positive electrode slurry comprising the aforementioned positive electrode active material, the aforementioned halide composite solid electrolyte, a conductive agent, and a binder can be coated onto at least one side of the positive electrode current collector to form a positive electrode active material layer, thereby obtaining a composite positive electrode sheet. The aforementioned positive electrode current collector may include an aluminum foil current collector.
[0060] This application also provides a solid-state battery, including the above-mentioned positive electrode, negative electrode and solid electrolyte.
[0061] Understandably, the aforementioned solid-state battery also includes a casing.
[0062] The solid electrolyte layer is a dense layer made of solid electrolyte material, and its function is to conduct lithium ions and isolate electrons.
[0063] Specifically, the solid electrolyte material in the solid electrolyte layer may include one or more of the following: sulfide electrolyte, oxide electrolyte, polymer electrolyte, and halide electrolyte.
[0064] The negative electrode sheet may include a negative current collector and a negative active layer located on at least one side of the negative current collector, wherein the negative active layer may include a negative active material (such as a lithium-ion battery negative active material) and a binder; and / or, a solid electrolyte; and / or, a conductive agent.
[0065] The aforementioned solid-state batteries may include square-shell batteries, cylindrical batteries, pouch batteries, etc.
[0066] Solid-state battery cells can be either wound cells or stacked cells.
[0067] This application also provides a method for preparing a solid-state battery, comprising:
[0068] The positive electrode active material (or negative electrode active material), solid electrolyte, conductive agent, and binder are mixed evenly by wet or dry methods and then coated onto at least one side of the positive electrode current collector (or negative electrode current collector). After drying (e.g., baking), a densification treatment (e.g., rolling) is performed to obtain a composite positive electrode sheet (or composite negative electrode sheet). The composite positive electrode sheet, solid electrolyte layer, and composite negative electrode sheet are then arranged in an orderly manner to obtain the electrode core. The electrode core is placed in the outer casing (casing) and subjected to isostatic pressing. Finally, formation and capacity testing are performed to obtain a solid-state battery.
[0069] This application also provides a battery assembly comprising at least two of the aforementioned solid-state batteries.
[0070] This application also provides an electrical device, including the above-mentioned solid-state battery or battery module, wherein the solid-state battery or battery module serves as the power supply for the electrical device.
[0071] The aforementioned electrical equipment may include at least one of electric vehicles, portable electronic devices, wearable devices, home appliances, and industrial equipment. Specifically, electric vehicles may include at least one of electric cars, electric bicycles, and electric scooters; portable electronic devices may include at least one of smartphones, laptops, and tablets; wearable devices may include at least one of smartwatches and fitness trackers; home appliances may include at least one of robotic vacuum cleaners and portable audio equipment; and industrial equipment may include drones.
[0072] In addition, it should be noted that the halide composite solid electrolyte provided in this application can also be used as a component in the composite solid electrolyte membrane between the positive electrode and the negative electrode.
[0073] The following is a detailed description using specific embodiments.
[0074] Example 1
[0075] (1) Using P123 as a template agent and tetraethyl orthosilicate as a silicon source, mesoporous SiO2 gel was prepared by evaporation-induced self-assembly. After calcination at 550℃, it was partially reduced with magnesium powder at 700℃ under an argon atmosphere to obtain a porous SiO2 framework material (specific surface area 320m² / g, average pore size 12nm);
[0076] (2) Weigh anhydrous LiCl and InCl3 in a molar ratio of 3:1, dissolve them in anhydrous acetonitrile, and stir magnetically until completely dissolved to obtain a 0.5M Li3InCl6 precursor solution;
[0077] (3) Immerse 1g of porous SiO2 framework in 20mL of the above precursor solution and vacuum impregnate at 30°C for 6 hours to ensure full penetration and obtain impregnated material.
[0078] (4) The impregnating material is dried in a vacuum oven at 80°C for 12 hours, then transferred to a tube furnace and heated to 250°C at 2°C / min under argon protection. It is kept at this temperature for 8 hours, and then ground after natural cooling to obtain a halide composite solid electrolyte, in which SiO2 accounts for about 5% by mass.
[0079] Example 2
[0080] The preparation steps are the same as in Example 1, except that the volume of the precursor solution and the amount of porous SiO2 are adjusted so that the mass ratio of SiO2 in the halide composite solid electrolyte is about 10%.
[0081] Example 3
[0082] The preparation steps are the same as in Example 1, except that the volume of the precursor solution and the amount of porous SiO2 are adjusted so that the mass ratio of SiO2 in the halide composite solid electrolyte is about 15%.
[0083] Example 4
[0084] The preparation steps are the same as in Example 1, except that the volume of the precursor solution and the amount of porous SiO2 are adjusted so that the mass ratio of SiO2 in the halide composite solid electrolyte is about 30%.
[0085] Example 5
[0086] The preparation steps are the same as in Example 1, except that the volume of the precursor solution and the amount of porous SiO2 are adjusted so that the mass ratio of SiO2 in the halide composite solid electrolyte is about 1%.
[0087] The preparation steps of Examples 6 and 7 are the same as those of Example 1, except that the specific surface area, average pore size, and particle size of the prepared porous SiO2 are adjusted by adjusting the concentration of the template agent and the silicon source, as shown in Table 1.
[0088] Example 8
[0089] The preparation steps in this embodiment are the same as in Example 1, except that the porous SiO2 prepared in step 1 is dried and dispersed in anhydrous toluene. Dodecyltriethoxysilane (the molar ratio of dodecyltriethoxysilane to surface hydroxyl groups is 1:1) is added under a nitrogen atmosphere, and the mixture is stirred at reflux at 110°C for 12 hours. After the reaction is complete, the mixture is washed multiple times with a mixed solution of ethanol and acetone, and then vacuum dried at 60–80°C to obtain hydrophobically modified porous SiO2.
[0090] Comparative Example 1
[0091] Li3InCl6 halide solid electrolyte powder was synthesized directly using a high-temperature solid-state method. After thoroughly mixing and grinding stoichiometric amounts of LiCl and InCl3, the mixture was sintered at 250°C for 8 hours in a vacuum-sealed quartz tube to obtain pure-phase Li3InCl6 electrolyte powder.
[0092] Comparative Example 2
[0093] The preparation steps are the same as in Example 1, except that the volume of the precursor solution and the amount of porous SiO2 are adjusted so that the mass ratio of SiO2 in the halide composite solid electrolyte is about 50%.
[0094] Comparative Example 3 follows the same preparation steps as Example 1, except that the specific surface area, average pore size, and particle size of the prepared porous SiO2 are adjusted by adjusting the stencil concentration and silicon source, as shown in Table 1.
[0095] Test Example 1
[0096] Mass content of porous SiO2 framework: The weighed halide composite solid electrolyte including silicon dioxide was soaked in ethanol for 24 hours. After soaking, the electrolyte was removed by washing with ethanol. Then, it was dried, and the mass of the porous SiO2 framework was weighed again to calculate the mass content of the porous SiO2 framework.
[0097] The specific surface area and average pore size of the porous SiO2 framework were obtained by BET method.
[0098] The particle size Dv50 of the porous SiO2 framework was obtained by laser particle size analyzer.
[0099] Table 1. Structural parameters of halide composite solid electrolytes
[0100]
[0101] Test Example 2
[0102] Ionic conductivity test: 100 mg of halide composite solid electrolyte was weighed and placed in a mold for pressurization at 300 MPa. Under pressure, the impedance value of the electrolyte material was measured at room temperature (25°C) using an electrochemical workstation and electrochemical impedance spectroscopy. The real value of the impedance at the point where the absolute minimum phase of multiple impedances was measured was taken as the impedance value (RSE) of the electrolyte material. The ionic conductivity was calculated using this resistance value.
[0103] Air stability test: The halide composite solid electrolyte was placed in a constant temperature and humidity chamber (25℃, 30% relative humidity) for 24 hours, and then the ionic conductivity was tested. The conductivity retention rate was calculated. The test results are detailed in Table 2.
[0104] Table 2. Performance of halide composite solid electrolytes
[0105]
[0106] Examples 1-5 show that the air stability of the composite solid electrolyte is significantly improved with the increase of porous SiO2 content. After exposure to 30% humidity for 24 hours, Examples 2 and 3 both exhibited conductivity retention of over 90%, demonstrating excellent moisture resistance while maintaining an ionic conductivity greater than 0.6 mS / cm.
[0107] Although the initial ionic conductivity of the composite electrolytes in each embodiment is slightly lower than that of pure halides (Comparative Example 1), it still remains on the order of mS / cm when the SiO2 content is 5-10%, fully meeting the application requirements of solid-state batteries. This demonstrates that the present invention improves air stability with virtually no sacrifice in high ionic conductivity.
[0108] Compared to Example 6, Example 1 has an increased specific surface area, an increased number of pore structures, and improved moisture resistance.
[0109] Compared to Example 1, Example 8 shows a slight improvement in moisture resistance after the porous silica surface is modified with alkyl chains.
[0110] The pure halide electrolyte in Comparative Example 1 had already deliquesced and failed under the same conditions.
[0111] In Comparative Example 2, the addition of too much porous silica resulted in a decrease in ionic conductivity.
[0112] In Comparative Example 3, the porous silica has too little specific surface area and poor moisture resistance.
[0113] The halide composite solid electrolytes obtained from the above embodiments and comparative examples after 24 hours of exposure were added to the composite positive electrode to form a positive electrode layer, and the corresponding electrolytes were used as the electrolyte layer. Metallic lithium was used as the negative electrode to assemble an all-solid-state battery. Specifically:
[0114] (1) Preparation of the positive electrode:
[0115] A positive electrode film is prepared by mixing lithium-rich manganese-based positive electrode material, electrolyte exposed for 24 hours, conductive agent (VGCF), and binder (PTFE) in a mass ratio of 70:30:2:0.5. The positive electrode film is then combined with stainless steel to form a positive electrode sheet.
[0116] (2) Lithium metal is used as the negative electrode.
[0117] (3) Preparation of sulfide solid electrolyte membrane: Sulfide electrolyte (Li6PS5Cl) and binder (PTFE) are thoroughly mixed at a mass ratio of 100:0.5 to prepare electrolyte membrane.
[0118] The negative electrode, sulfide solid electrolyte, and positive electrode are stacked sequentially to obtain the electrode core. After the electrode core is fitted into an aluminum-plastic film shell, it is subjected to isostatic pressing at 400MPa, followed by formation and capacity testing to obtain a solid-state battery.
[0119] Test Example 3
[0120] First charge / discharge test: The solid-state battery was tested at 25℃ with a constant current of 0.1C for one cycle, with a voltage range of 2.0-4.8V.
[0121] 2) Cyclic performance test: The solid-state battery is subjected to 100 cycles of constant current charge and discharge at 0.1C at 25℃, with a voltage range of 2.0-4.8V.
[0122] Table 3. Battery Performance
[0123]
[0124] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.
Claims
1. A halide composite solid electrolyte, characterized in that, include: A porous SiO2 framework and a halide solid electrolyte are provided. The porous SiO2 framework has a continuous and interconnected pore structure. The halide solid electrolyte is partially grown to fill the pore structure of the porous SiO2 framework and partially grown to coat the surface of the porous SiO2 framework. The Si-O bonds on the surface of the porous SiO2 framework preferentially capture water molecules and inhibit the hydrolysis of M-Cl bonds in the halide. The interface between the porous SiO2 framework and the halide solid electrolyte includes a transition layer, which contains Si-O-metal bonds. Based on a halide composite solid electrolyte, the porous SiO2 framework has a mass content of 1 wt% to 30 wt%. The specific surface area of the porous SiO2 framework is 50-500 m². 2 / g; The particle size Dv50 of the porous SiO2 framework is 0.2μm~0.7μm.
2. The halide composite solid electrolyte according to claim 1, characterized in that, The average pore size of the porous SiO2 framework is 5-50 nm.
3. The halide composite solid electrolyte according to claim 1 or 2, characterized in that, The porous SiO2 framework has a mass content of 5 wt% to 10 wt%.
4. The halide composite solid electrolyte according to claim 1 or 2, characterized in that, The porous SiO2 framework is a hydrophobic SiO2 modified with alkyl chains.
5. The halide composite solid electrolyte according to claim 1 or 2, characterized in that, The chemical formula of the halide solid electrolyte is Li a M x X y Where X is selected from one or more of chlorine, bromine, and iodine, M is selected from one or more of Y, In, Sc, Al, Zr, Hf, and Ta, and the values of a, x, and y satisfy the stoichiometric coefficients for valence equilibrium.
6. The halide composite solid electrolyte according to claim 3, characterized in that, After being exposed to 30% humidity for 24 hours, the halide composite solid electrolyte exhibits an ionic conductivity ≥0.78 mS / cm and a retention rate of ≥85% for its ionic conductivity.
7. A method for preparing a halide composite solid electrolyte according to any one of claims 1-6, characterized in that, Includes the following steps: The raw materials of the halide solid electrolyte are dissolved in an aprotic solvent to prepare a precursor solution; The porous SiO2 framework is immersed in the precursor solution, and after the impregnation treatment, it is dried to obtain the impregnated material. The impregnating material is subjected to heat treatment at a temperature of 200℃ to 500℃ for a time of 1 to 10 hours, so that the precursor reacts and crystallizes in situ within the pores of the porous SiO2 framework to obtain a halide composite solid electrolyte.
8. A positive electrode plate, characterized in that, The positive electrode includes a current collector, a positive electrode active material, and a halide composite solid electrolyte as described in any one of claims 1-6.
9. A solid-state battery, characterized in that, It includes the positive electrode, negative electrode, and solid electrolyte as described in claim 8.