A double-silver argyrodite composite solid electrolyte material and a synthesis process thereof

Abstract

This invention relates to the field of solid-state electrolytes and all-solid-state battery materials, and particularly to a disulfide-silver-germanium ore composite solid-state electrolyte material and its synthesis process. The composite solid-state electrolyte material comprises a mol% Li6PS5Cl phase and b mol% Li6SbS5I phase, wherein the Li6PS5Cl phase is used to construct lithium-ion transport channels, and the Li6SbS5I phase is used to improve the composite solid-state electrolyte material's stability to air humidity. The synthesis process includes any one of the following: separate synthesis followed by composite process, one-step solid-state sintering process, and liquid-phase assisted composite process, thereby enabling the material to maintain a high room-temperature ionic conductivity while also ensuring air humidity stability.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte and all-solid-state battery materials, and particularly to a disulfide silver germanium ore composite solid electrolyte material and its synthesis process. Background Technology

[0002] Solid-state electrolytes are ionic conductors and electronic insulators that exist in a solid state. Compared to liquid organic electrolytes, solid-state electrolytes are expected to improve battery safety and support the application potential of high-specific-capacity anode systems such as lithium metal; however, achieving high ionic conductivity at room temperature while ensuring processability and environmental stability remains a key challenge for industrialization.

[0003] In sulfide solid electrolyte systems, materials represented by silver-germanium sulfide ore have attracted attention due to their high ionic conductivity, with Li6PS5Cl often being used as a typical component of high ionic conductivity sulfide electrolytes. However, Li6PS5Cl is quite sensitive to air and humidity; exposure to air humidity may lead to side reactions and performance degradation, thereby increasing the dependence of its preparation, transfer, and assembly on low-oxygen environments.

[0004] On the other hand, Li6SbS5I also belongs to the sterhenite structure, and its reactivity with water molecules is relatively low, which can improve the material's resistance to air humidity, but its ionic conductivity is relatively low. Improving moisture resistance solely through a single component may not simultaneously meet the comprehensive requirements of high ionic conductivity, moisture resistance, and process compatibility. Therefore, a composite solid-state electrolyte material and its synthesis process that can achieve complementary performance at the material system level are needed. Summary of the Invention

[0005] The purpose of this invention is to provide a disulfiram-germanium ore composite solid electrolyte material and its synthesis process, so as to improve the resistance to high air humidity while maintaining the high room temperature ionic conductivity of the disulfiram-germanium ore material.

[0006] On one hand, this invention provides a disulfide-silver germanium ore composite solid electrolyte material, comprising a mol% of Li6PS5Cl phase and b mol% of Li6SbS5I phase, wherein a+b=100, and the values ​​of a and b are both 20-80; the Li6PS5Cl phase is used to construct lithium-ion transport channels, and the Li6SbS5I phase is used to improve the humidity stability of the material under short-term exposure to air at 50% relative humidity for 5 minutes; in the composite solid electrolyte material, the Li6PS5Cl phase and the Li6SbS5I phase each maintain a complete and independent disulfide-silver germanium ore crystal structure; the composite solid electrolyte material has at least one of the following microstructures:

[0007] When a=65~80 and b=20~35, Li6PS5Cl is the continuous phase and Li6SbS5I is the dispersed phase, or Li6SbS5I is coated with Li6PS5Cl in a continuous / discontinuous coating layer.

[0008] When a=20~35 and b=65~80, Li6SbS5I is the continuous phase and Li6PS5Cl is the dispersed phase.

[0009] When both a and b are 40–60, the Li6PS5Cl phase and the Li6SbS5I phase form a two-way interpenetrating network.

[0010] More preferably, the basic form of the composite solid electrolyte material is powder or tablet; a binder is added when preparing the coating and electrolyte membrane, and the binder is at least one of PVDF and PTFE, and the amount of binder added is 0.1 to 10 wt% of the total mass of the composite solid electrolyte material.

[0011] On the other hand, the present invention provides a synthesis process for a disulfide silver germanium ore composite solid electrolyte material as described in any of the above claims, including any one of a separate synthesis and then composite process, a one-step solid-phase sintering process with one-time feeding, and a liquid-phase assisted composite process, wherein the liquid-phase assisted composite process includes two sub-routes: direct dispersion of Li6SbS5I powder and in-situ coating of Li6SbS5I precursor.

[0012] More preferably, the composite process after separate synthesis includes: preparing Li6PS5Cl powder and Li6SbS5I powder respectively; mixing the Li6PS5Cl powder and the Li6SbS5I powder at a molar ratio of (20~80):(20~80); the mixing method is grinding, mechanical mixing or ball milling, so that the Li6SbS5I phase is distributed between the Li6PS5Cl phase, or the Li6SbS5I phase forms a continuous or discontinuous coating layer on the surface of the Li6PS5Cl powder; finally, the powder is directly taken and pressed into sheets at 200~500MPa, or a coating / film is made by adding a binder.

[0013] More preferably, the one-step solid-state sintering process includes: feeding Li2S, P2S5, Sb2S3, LiCl, LiI, and S into the target composition in one step, mixing, ball milling, and solid-state sintering under an inert atmosphere or vacuum sealing conditions, with a ball-to-material ratio of 5:1 to 20:1, a rotation speed of 300 to 600 rpm, a ball milling time of 5 to 30 hours, a solid-state sintering temperature of 450 to 600℃, and a sintering time of 2 to 20 hours; to obtain a disulfide silver germanium ore composite solid electrolyte material containing Li6PS5Cl phase and Li6SbS5I phase.

[0014] More preferably, the liquid-phase assisted composite process is carried out entirely in a low-water, low-oxygen environment, with a dew point ≤ -60℃ and both water and oxygen content ≤ 1ppm; the solvent is an anhydrous aprotic organic solvent selected from CH3CN, C4H8O, and C4H 10 O2, C7H8, C6H 14 and C7H 16 At least one of them, the solid-liquid ratio of the total solid mass to the volume of the anhydrous aprotic organic solvent is 1 g:(5-30) mL.

[0015] More preferably, the direct dispersion sub-route of Li6SbS5I powder is as follows: Li6PS5Cl powder and Li6SbS5I powder are prepared in advance, the Li6SbS5I powder is dispersed in a solvent to form a suspension, and after adding Li6PS5Cl powder, the mixture is treated by stirring at 200-800 rpm for 0.5-12 h, sonicating for 5-60 min, or a combination of both. Subsequently, the solvent is removed at 40-60℃ for 0.5-3 h, and after removing the solvent, the mixture is dried at 60-120℃ for 4-12 h or annealed at 450-550℃ for 2-8 h to obtain the composite solid electrolyte material.

[0016] More preferably, the in-situ coating sub-route of the Li6SbS5I precursor is as follows: Li6PS5Cl powder is prepared in advance, and Li2S, Sb2S3, LiI, and S are mixed in a molar ratio of 5:1:2:2 to prepare the Li6SbS5I precursor. The Li6SbS5I precursor is dispersed in a solvent, and Li6PS5Cl powder is added. The mixture is then stirred at 200-800 rpm for 0.5-12 h and sonicated for 5-60 min, or a combination of both. Subsequently, the solvent is removed at 40-60℃ for 0.5-3 h, and after solvent removal, the mixture is dried at 60-120℃ for 4-12 h or annealed at 450-550℃ for 2-8 h, so that the Li6SbS5I phase forms a continuous or discontinuous coating layer on the surface of the Li6PS5Cl powder in situ, thereby obtaining a composite solid electrolyte material.

[0017] More preferably, the molar ratio of Li6PS5Cl to Li6SbS5I or its precursor is any one of 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, and 20:80.

[0018] Compared with the prior art, the present invention has the following advantages: the present invention, through the compositing of Li6PS5Cl phase and Li6SbS5I phase, enables the Li6PS5Cl phase and Li6SbS5I phase to maintain their respective silver-sulfur germanite-type crystal structures and coexist as two functional phases that can be distinguished from crystallography. Both phases exist in a significant proportion, forming a continuous Li6SbS5I phase and a dispersed Li6PS5Cl phase, as well as interpenetrating networks or surface-coated structures. The coexistence of the two phases creates numerous Li6PS5Cl / Li6SbS5I heterogeneous interfaces. These interfaces are no longer obstructive grain boundaries in the conventional sense, but rather participate in connecting the Li⁺ transport networks in the two phases, forming additional cross-phase migration paths and thus improving the overall lithium-ion transport capacity. Simultaneously, the Li6SbS5I phase, which has high humidity stability, is distributed around the Li6PS5Cl grains, at the grain boundaries between the two phases, or on the powder surface. This reduces the direct contact between Li6PS5Cl and ambient moisture, inhibits its hydrolysis reaction, and enables the Li6PS5Cl phase to provide high lithium-ion conductivity. The Li6SbS5I phase improves its resistance to air humidity, thereby maintaining the high room temperature ionic conductivity of the silver-sulfur germanium ore material while also ensuring high water stability. Attached Figure Description

[0019] Figure 1 This is the XRD pattern of the disulfide silver germanium ore composite solid electrolyte material in the embodiments of this application. Detailed Implementation

[0020] The following describes in detail, with reference to the accompanying drawings, the implementation methods of the composite solid electrolyte material of this application, its preparation method, characterization method, and theoretical analysis.

[0021] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0022] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0023] In this application, halogens include at least one of F, Cl, and I.

[0024] Example 1: This example provides a disulfide silver germanium ore composite solid electrolyte material, which is composed of two sulfide solid electrolytes, Li6SbS5I and Li6PS5Cl.

[0025] Li6PS5Cl, belonging to the argyrocerium sulfide structure, exhibits high room-temperature ionic conductivity, which stems from abundant lithium vacancies and a low lithium-ion migration barrier within its crystal structure. However, Li6PS5Cl is sensitive to air humidity; when exposed to humid environments, the PS4 tetrahedra readily react with water molecules, leading to degradation of the material's structure and performance.

[0026] Li6SbS5I also possesses a steric argillacene structure, where Sb substitutes for P sites and I substitutes for Cl sites. The Sb-S bond exhibits lower reactivity than the PS bond, and the introduction of I further alters the surface chemistry of the material, reducing the adsorption capacity of Li6SbS5I for water molecules and decreasing its reactivity with water, thus demonstrating better humidity stability.

[0027] This application achieves synergistic optimization of performance by combining the two materials in a certain proportion, utilizing Li6PS5Cl to provide high ionic conductivity and Li6SbS5I to provide humidity protection.

[0028] In some embodiments, since the performance of the composite solid electrolyte material depends not only on its composition but also on its microstructure, this embodiment proposes various microstructure designs: In a continuous-dispersed phase structure, when one component has a high content, it can form a continuous phase, while the other component is distributed as a dispersed phase within it; in a two-phase interpenetrating network structure, the two phases each form a continuous network, and lithium ions can be transported through either network; in a coating structure, Li6SbS5I forms a coating layer on the surface of Li6PS5Cl powder, and the outer Li6SbS5I layer can isolate ambient moisture and protect the internal high-conductivity Li6PS5Cl phase. The above-mentioned continuous-dispersed phase structure, interpenetrating network structure, and coating structure can exist individually or in various combinations within the same composite solid electrolyte material.

[0029] Example 2: Based on Example 1, this example provides a synthesis process for the separate synthesis and subsequent composite synthesis of a disulfide silver germanium ore composite solid electrolyte material, specifically including the following steps:

[0030] Step 1: Prepare Li6PS5Cl powder and Li6SbS5I powder separately. In an argon-atmospheric glove box, weigh the raw materials according to the molar ratio Li2S:P2S5:LiCl = 5:1:2. Premix in a mortar for 30 minutes, then mechanically ball-mill at a ball-to-material ratio of 10:1, a rotation speed of 500 rpm, and a milling time of 12 hours to obtain Li6PS5Cl precursor powder. After ball milling, transfer the precursor powder to a quartz tube, vacuum seal it, and anneal at 500~550℃ for 5 hours to obtain Li6PS5Cl powder.

[0031] In an argon-atmospheric glove box, raw materials were weighed with a molar ratio of Li2S:Sb2S3:LiI:S = 5:1:2:2. The raw materials were premixed in a mortar for 30 minutes and then mechanically ball-milled at a ball-to-material ratio of 10:1, a rotation speed of 500 rpm, and a ball-milling time of 12 hours to obtain Li6SbS5I precursor powder. After ball milling, the precursor powder was transferred to a quartz tube, vacuum sealed, and annealed at 450~550℃ for 5 hours to obtain Li6SbS5I powder.

[0032] Step 2: Weigh and combine the Li6PS5Cl powder and Li6SbS5I powder obtained in Step 1 according to the target ratio. Based on a total molar percentage of 100 mol% for Li6PS5Cl and Li6SbS5I in the composite solid electrolyte, the molar percentage of Li6PS5Cl is 20-80 mol%, and the molar percentage of Li6SbS5I is 20-80 mol%. In Examples 6 to 18, the molar ratio of Li6PS5Cl powder to Li6SbS5I powder is 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, or 20:80. The weighed Li6PS5Cl powder and Li6SbS5I powder were subjected to any of the following composite treatments in a glove box: mortar and pestle grinding for 30 minutes; mechanical mixing at 300-500 rpm for 0.5-2 hours; low-energy ball milling at 200 rpm for 2 hours; or surface coating treatment, followed by low-energy ball milling at 200 rpm for 2 hours and annealing at 500℃ for 5 hours. After the above treatments, the Li6SbS5I phase is distributed between the Li6PS5Cl phases, or the Li6SbS5I phase forms a continuous or discontinuous coating layer on the surface of the Li6PS5Cl powder, thus forming a composite solid electrolyte powder with core-shell structure characteristics.

[0033] Step 3: Place the solid electrolyte powder obtained in Step 2 into a mold, apply a pressure of 200~500MPa on a tablet press and hold the pressure for 1~5 minutes to obtain an electrolyte tablet; or grind and mix the powder with an optional binder in a glove box for 10~30 minutes, or stir in an anhydrous organic solvent at 300~800 rpm for 0.5~4 hours to prepare an electrolyte membrane or coating, and vacuum dry at 60~80℃ for 4~8 hours.

[0034] In some embodiments, the binder includes PVDF and / or PTFE, and the amount of binder added is 3 wt% of the total mass of the composite solid electrolyte material.

[0035] Example 3: Based on Example 1, this example provides a one-step solid-state sintering process for a disulfide silver germanium ore composite solid electrolyte material. Let the molar amount of the target substance in the Li6PS5Cl phase of the target product be x mol, and the molar amount of the target substance in the Li6SbS5I phase be y mol. Then, the raw materials are weighed in molar amounts as follows: Li2S = (2.5x + 2.5y) mol, P2S5 = 0.5x mol, LiCl = x mol, Sb2S3 = 0.5y mol, LiI = y mol, and S = y mol. The above raw materials were premixed in an inert atmosphere for 30 minutes and then ball-milled at a ball-to-material ratio of 5:1 to 20:1, at a speed of 300 to 600 rpm, for a time of 5 to 30 hours. Subsequently, the materials were solid-state sintered at 450 to 600°C for 2 to 20 hours under vacuum sealing or inert atmosphere protection to form the Li6PS5Cl phase and Li6SbS5I phase in situ in the system, thus obtaining the disulfide silver germanium ore composite solid electrolyte material.

[0036] In Examples 20 and 21, the ball-to-material ratio was 10:1, the rotation speed was 500 rpm, the ball milling time was 12 hours, the solid-state sintering temperature was 500℃, and the sintering time was 5 hours. This one-step solid-state sintering process with a single feed reduces intermediate transfer steps and creates a composite system with two coexisting phases.

[0037] Example 4: Based on Example 1, this example provides a liquid-phase assisted composite process for a disulfide silver germanium ore composite solid electrolyte material. Since Li6PS5Cl is not suitable for direct liquid-phase synthesis, in this example, Li6PS5Cl powder is prepared beforehand using a solid-phase method. Then, Li6SbS5I powder or a Li6SbS5I precursor is dispersed in an anhydrous aprotic organic solvent to form a dispersion or suspension, which then contacts and composites with the Li6PS5Cl powder. Specific solid-liquid ratios, ultrasonic time, stirring speed and time, solvent removal temperature and time, drying temperature and time, and annealing temperature and time for liquid-phase assisted composite are detailed in Examples 22 and 23 and Table 3.

[0038] The anhydrous aprotic organic solvent includes at least one selected from anhydrous acetonitrile, tetrahydrofuran, 1,2-dimethoxyethane, toluene, n-hexane, and heptane. In Example 22, the powder direct dispersion composite method used CH3CN with a solid-liquid ratio of 1 g:10 mL. The mixture was first sonicated for 30 minutes, then stirred at 500 rpm for 4 hours, and rotary evaporated at 45°C for 1 hour to remove most of the solvent. Subsequently, it was vacuum dried at 80°C for 8 hours and annealed at 500°C for 5 hours. In Example 23, the precursor in-situ composite method used CH3CN with a solid-liquid ratio of 1 g:12 mL. The mixture was first sonicated for 20 minutes, then stirred at 500 rpm for 6 hours, and rotary evaporated at 45°C for 1 hour to remove most of the solvent. Subsequently, it was vacuum dried at 80°C for 8 hours and annealed at 500°C for 5 hours. Liquid-phase assisted composite, sample transfer before and after solvent removal, drying and loading, and annealing and packaging processes were all carried out in an Ar atmosphere glove box or under a sealed inert atmosphere. The glove box dew point was -65°C, the water content was 0.6 ppm, and the oxygen content was 0.5 ppm. The in-situ coating process of the Li6SbS5I precursor in Example 23 was carried out in an Ar atmosphere glove box with a dew point of -66°C, a water content of 0.5 ppm, and an oxygen content of 0.5 ppm to avoid side reactions between the sulfide solid electrolyte and water.

[0039] Example 5: Based on any of Examples 1 to 4, when the composite solid electrolyte material needs to be prepared as an electrolyte membrane, coating or molded body, a binder can be further added; the binder includes PVDF and / or PTFE, and the amount of binder added is 3wt% of the total mass of the composite solid electrolyte material; when the composite solid electrolyte material is used in the form of powder or tablet, the binder may not be added.

[0040] This application employs multiple theoretical calculation methods to analyze and predict the performance of composite solid electrolyte materials: based on density functional theory, calculations are performed using the VASP software package, and the exchange correlation functional is approximated using the PBE generalized gradient approximation; the crystal structures of Li6PS5Cl and Li6SbS5I are geometrically optimized; the lithium-ion migration barrier is calculated using the CI-NEB method; humidity stability analysis is achieved by calculating the adsorption energy and reaction energy of water molecules on the material surface; to study the ion transport characteristics of the Li6PS5Cl / Li6SbS5I interface, a two-phase interface model is constructed and the energy barrier for lithium-ion cross-interface migration is calculated.

[0041] Examples 6-18: Based on Example 2, experiments were conducted using composite solid electrolyte materials with different ratios, as shown in Table 1.

[0042] In an argon atmosphere glove box with a dew point below -60℃, the pre-prepared Li6PS5Cl and Li6SbS5I powders were weighed according to the molar ratio shown in Table 1, ground and mixed in a mortar for 30 minutes, and then pressed into an electrolyte tablet with a diameter of 10 mm and a thickness of about 1 mm under a pressure of 300 MPa.

[0043] Comparative Example 1: Pure Li6PS5Cl. Pure Li6PS5Cl electrolyte tablets were prepared as a comparative example using the same method as in Examples 6-18.

[0044] Comparative Example 2: Pure Li6SbS5I. Pure Li6SbS5I electrolyte tablets were prepared as comparative examples using the same method as in Examples 6-18.

[0045] Performance testing:

[0046] The solid electrolytes from Examples 6-18 and Comparative Examples 1-2 were tested as follows:

[0047] ① Perform XRD testing on the solid electrolyte. Grind the sample into a fine powder using a mortar and pestle in a glove box for 5–10 minutes, or using a ball mill at 200 rpm for 10–20 minutes, and then compress the powder into a pellet. The X-ray source is Cu-Kα, the scanning range is 10°–60°, the step interval is 0.01°, the scanning speed is 1° / minute, and the operating voltage and current are 40 kV and 40 mA, respectively. After preparation in the glove box, the sample is transferred to the diffractometer using a sealed sample holder to avoid air exposure.

[0048] The XRD test results for the composite solid electrolyte in Example 6 are shown below. Figure 1 .like Figure 1 As shown, the composite material exhibits a characteristic peak of the Li6SbS5I phase at 2θ≈29.0° and a characteristic peak of the Li6PS5Cl phase at 2θ≈29.8°. The two peaks are close in position but can be distinguished, indicating the coexistence of the two phases in the composite sample.

[0049] ② Ionic conductivity test of solid electrolyte. Solid electrolyte powder was uniformly placed in a mold and pressed using a tablet press at 300 MPa to form a uniform ceramic sheet. In an Ar atmosphere, two lithium metal sheets were placed on either side of the solid electrolyte ceramic sheet, forming a symmetrical cell with lithium metal on both sides and solid electrolyte in the middle. Electrochemical impedance spectroscopy (EIS) was performed on the assembled symmetrical cell. The EIS spectrum of the full cell was measured at 25°C, with a frequency range of 3 MHz to 1 Hz, an AC voltage amplitude of 5 mV, and a DC bias of 0 V. The relevant EIS spectra were then fitted. The conductivity of the solid electrolyte is calculated using the formula: σ = L / (R·A), where σ is the conductivity of the solid electrolyte (S·cm⁻¹); L is the thickness of the solid electrolyte tablet (cm); R is the resistance of the solid electrolyte ceramic sheet (Ω); and A is the cross-sectional area of ​​the solid electrolyte ceramic sheet through which current flows (cm²). Ionic conductivity in the table is expressed in mS·cm⁻¹.

[0050] ③ Impedance of solid electrolyte exposed to air at 50% relative humidity. After exposing the solid electrolyte sample to air at 50% relative humidity for 5 minutes, the same solid electrolyte ionic conductivity test as in ② was performed.

[0051] Table 1. Solid electrolyte parameters of Examples 6 to 18 and Comparative Examples 1 to 2

[0052]

[0053] As can be seen from the results in Table 1, compared with the conventional solid electrolyte Li6PS5Cl in Comparative Example 1, the composite solid electrolyte used in this application embodiment significantly improves humidity stability while maintaining high ionic conductivity.

[0054] Specifically, although Comparative Example 1 has a high initial ionic conductivity, its ionic conductivity drops sharply after exposure to 50% relative humidity for 5 minutes, indicating that it is extremely sensitive to humidity and cannot work stably in normal air environments, severely limiting its practical application scenarios. Comparative Example 2 has better humidity stability, but its initial ionic conductivity is much lower than that of Comparative Example 1, which cannot meet the requirements of solid-state batteries for high ion transport capacity. In contrast, the composite solid-state electrolyte material of this application successfully balances high ionic conductivity and humidity stability. By constructing a disulfide silver-germanium mineral phase composite structure, it successfully overcomes the inherent defects of the above single-phase materials, achieving a synergistic balance between high ionic conductivity and excellent humidity stability, and solving the technical contradiction that existing single-phase materials cannot simultaneously meet the requirements of high conductivity and humidity resistance.

[0055] As the molar percentage of Li6SbS5I increased from 20 mol% to 70 mol%, the conductivity increased from 5.0 mS / cm to 14.0 mS / cm. After further increasing to 75-80 mol%, the initial conductivity decreased, but the ionic conductivity increased after exposure to 50% relative humidity for 5 minutes. This result indicates that the two-phase composite can form a synergistic balance between lithium-ion transport and air humidity stability.

[0056] To further classify different microstructures, this application categorizes representative samples in Table 1 according to phase content ranges, as shown in Table 2. Here, RH represents relative humidity, which is the ratio of the actual partial pressure of water vapor in the air to the saturated water vapor pressure at the same temperature. "Ion conductivity after 5 min of exposure to 50% RH" refers to the ionic conductivity of the solid electrolyte sample measured after exposure to air with a relative humidity of 50% for 5 min. In Table 2 and Table 3 below, "after RH" indicates relative humidity treatment, i.e., "after exposure to air with a relative humidity of 50% for 5 min". A Li6PS5Cl phase content of 65–80 mol% corresponds to the Li6PS5Cl continuous phase and the Li6SbS5I dispersed phase; a Li6SbS5I phase content of 65–80 mol% corresponds to the Li6SbS5I continuous phase and the Li6PS5Cl dispersed phase; and a content of 40–60 mol% for both phases corresponds to two interpenetrating networks.

[0057] Table 2. Different microstructures and corresponding performance data

[0058]

[0059] Examples 19-23: Based on Examples 2 to 4, the surface coating composite after separate synthesis, one-step solid-state sintering with one-time feeding, and liquid-phase assisted composite processes were further verified. Unless otherwise specified, the surface coating composite of the separately synthesized components in Example 19 was performed by low-energy ball milling at 200 rpm for 2 hours and annealing at 500°C for 5 hours; the one-step solid-phase sintering of the single-feeding components in Examples 20 and 21 was performed by ball milling at 500 rpm for 12 hours and sintering at 500°C for 5 hours with a ball-to-material ratio of 10:1; the direct dispersion composite of the powder in Example 22 was performed by a solid-liquid ratio of 1 g:10 mL, ultrasonication for 30 minutes, stirring at 500 rpm for 4 hours, rotary evaporation at 45°C for 1 hour, vacuum drying at 80°C for 8 hours, and annealing at 500°C for 5 hours; the in-situ composite of the precursor in Example 23 was performed by a solid-liquid ratio of 1 g:12 mL, ultrasonication for 20 minutes, stirring at 500 rpm for 6 hours, rotary evaporation at 45°C for 1 hour, vacuum drying at 80°C for 8 hours, and annealing at 500°C for 5 hours.

[0060] Table 3. Different synthesis processes and corresponding performance data

[0061]

[0062] As shown in Table 3, apart from the separate synthesis and subsequent composite process, the one-step solid-state sintering process and the liquid-phase assisted composite process can also obtain a disulfide silver germanium ore composite solid electrolyte material containing both Li6PS5Cl and Li6SbS5I phases. The initial room temperature ionic conductivity of each embodiment is not less than 0.5 mS / cm, and after exposure to air at 50% relative humidity for 5 minutes, the ionic conductivity retention rate is not less than 50%, indicating that the above different processes can achieve the technical effect of balancing ionic conductivity and air humidity stability.

[0063] From a theoretical calculation perspective, this synergistic effect can be attributed to the following: the adsorption of water molecules on the Li6SbS5I surface is weaker, and the SbS4 tetrahedron has lower hydrolysis reactivity than the PS4 tetrahedron; at the same time, the ion transport barrier at the interface between the Li6PS5Cl and Li6SbS5I phases is moderate and will not become a serious ion transport obstacle.

[0064] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A disulfide-germanium ore composite solid electrolyte material, characterized in that, The material comprises a mol% Li6PS5Cl phase and b mol% Li6SbS5I phase, where a+b=100 and a and b are both between 20 and 80. The Li6PS5Cl phase is used to construct lithium-ion transport channels, and the Li6SbS5I phase is used to improve the humidity stability of the material under short-term exposure to air at 50% relative humidity for 5 minutes. In the composite solid electrolyte material, the Li6PS5Cl phase and the Li6SbS5I phase each maintain a complete and independent silver-germanium sulfide crystal structure; the composite solid electrolyte material possesses at least one of the following microstructures: When a=65~80 and b=20~35, Li6PS5Cl is the continuous phase and Li6SbS5I is the dispersed phase, or Li6SbS5I is coated with Li6PS5Cl in a continuous / discontinuous coating layer. When a=20~35 and b=65~80, Li6SbS5I is the continuous phase and Li6PS5Cl is the dispersed phase. When both a and b are 40–60, the Li6PS5Cl phase and the Li6SbS5I phase form a two-way interpenetrating network.

2. The disulfide-germanium ore composite solid electrolyte material according to claim 1, characterized in that, The basic form of the composite solid electrolyte material is powder or tablet; when preparing the coating and electrolyte membrane, a binder is added, wherein the binder is at least one of PVDF and PTFE, and the amount of binder added is 0.1 to 10 wt% of the total mass of the composite solid electrolyte material.

3. A synthesis process for the disulfide-germanium ore composite solid electrolyte material as described in any one of claims 1 to 2, characterized in that, This includes any one of the following: separate synthesis followed by composite process, one-step solid-state sintering process with single feeding, and liquid-phase assisted composite process. Among them, the liquid-phase assisted composite process includes two sub-routes: direct dispersion of Li6SbS5I powder and in-situ coating of Li6SbS5I precursor.

4. The synthesis process according to claim 3, characterized in that, The separate synthesis followed by composite process includes: preparing Li6PS5Cl powder and Li6SbS5I powder separately; mixing the Li6PS5Cl powder and the Li6SbS5I powder at a molar ratio of (20~80):(20~80); the mixing method is grinding, mechanical mixing, or ball milling, so that Li... 6S The bS5I phase is distributed between the Li6PS5Cl phase, or the Li6SbS5I phase forms a continuous or discontinuous coating layer on the surface of the Li6PS5Cl powder. Finally, the powder is directly taken and pressed into sheets at 200-500 MPa, or a coating / film is made by adding a binder.

5. The synthesis process according to claim 4, characterized in that, The one-step solid-state sintering process includes: feeding Li2S, P2S5, Sb2S3, LiCl, LiI, and S into the target composition in one step, mixing, ball milling, and solid-state sintering under an inert atmosphere or vacuum sealing condition, with a ball-to-material ratio of 5:1 to 20:1, a rotation speed of 300 to 600 rpm, a ball milling time of 5 to 30 hours, a solid-state sintering temperature of 450 to 600℃, and a sintering time of 2 to 20 hours; to obtain a disulfide silver germanium ore composite solid electrolyte material containing Li6PS5Cl phase and Li6SbS5I phase.

6. The synthesis process according to claim 5, characterized in that, The liquid-phase assisted composite process is carried out entirely in a low-water, low-oxygen environment, with a dew point ≤-60℃ and both water and oxygen content ≤1ppm. The solvent is an anhydrous aprotic organic solvent selected from CH3CN, C4H8O, and C4H4O. 10 O2, C7H8, C6H 14 and C7H 16 At least one of them, the solid-liquid ratio of the total solid mass to the volume of the anhydrous aprotic organic solvent is 1 g:(5-30) mL.

7. The synthesis process according to claim 6, characterized in that, Direct dispersion sub-route of Li6SbS5I powder: Li6PS5Cl powder and Li6SbS5I powder are prepared in advance. Li6SbS5I powder is dispersed in a solvent to form a suspension. After adding Li6PS5Cl powder, the mixture is stirred at 200-800 rpm for 0.5-12 h and ultrasonicated for 5-60 min, or a combination of both. Then, the solvent is removed at 40-60℃ for 0.5-3 h. After removing the solvent, the mixture is dried at 60-120℃ for 4-12 h or annealed at 450-550℃ for 2-8 h to obtain the composite solid electrolyte material.

8. The synthesis process according to claim 7, characterized in that, The in-situ coating sub-route for Li6SbS5I precursor is as follows: Li6PS5Cl powder is prepared in advance, and Li2S, Sb2S3, LiI, and S are mixed in a molar ratio of 5:1:2:2 to prepare Li6SbS5I precursor. The Li6SbS5I precursor is dispersed in a solvent, and Li6PS5Cl powder is added. The mixture is then stirred at 200-800 rpm for 0.5-12 h and sonicated for 5-60 min, or a combination of both. Subsequently, the solvent is removed at 40-60℃ for 0.5-3 h, and after solvent removal, the mixture is dried at 60-120℃ for 4-12 h or annealed at 450-550℃ for 2-8 h, so that the Li6SbS5I phase forms a continuous or discontinuous coating layer on the surface of Li6PS5Cl powder in situ, thus obtaining a composite solid electrolyte material.

9. The synthesis process according to claim 8, characterized in that, The molar ratio of Li6PS5Cl to Li6SbS5I or its precursor is any one of 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, or 20:80.

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