High-entropy sulfide solid electrolyte and preparation method thereof

Abstract

The invention discloses a high-entropy sulfide solid electrolyte and a preparation method thereof. The method comprises the following steps: weighing raw materials and carrying out ball milling; pressing to obtain a cold-pressed mixed precursor sheet; carrying out staged sintering on the cold-pressed mixed precursor sheet; quickly cooling; and grinding to obtain the high-entropy sulfide solid electrolyte. According to the embodiment, the high-entropy single-phase solid solution with high ionic conductivity and high interface stability is successfully prepared by adopting a collaborative process of stepped sintering and rapid quenching after sintering. A plurality of solid precursor sources are fully mixed through high-energy ball milling and then are subjected to stepped solid-phase sintering in a sealed environment. In the sintering process, a multi-stage heating and heat preservation process is adopted to ensure that each precursor source component can be uniformly heated and fully reacted in each temperature control stage, so that the formation of the high-entropy single-phase solid solution is effectively promoted.

Description

A high-entropy sulfide solid electrolyte and its preparation method Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to a high-entropy sulfide solid electrolyte and its preparation method. Background Technology

[0002] Traditional lithium-ion batteries, due to the flammability of their liquid electrolytes, are prone to thermal runaway, combustion, and even explosions when exposed to external forces or internal side reactions, posing significant safety hazards. Solid-state batteries not only solve these safety issues but also offer higher energy density and longer lifespan. Replacing traditional liquid electrolytes with solid-state electrolytes, and serving as the ion conductor in solid-state lithium batteries, is a very promising solution and an inevitable trend in lithium-ion battery development. Currently, solid-state electrolytes under research mainly include polymers, oxides, sulfides, and halides.

[0003] Among the electrolytes mentioned above, sulfide electrolytes exhibit high ionic conductivity, almost comparable to that of liquid electrolytes, and possess excellent mechanical properties, thus showing great promise for applications in solid-state batteries. However, the ionic conductivity of sulfide solid-state electrolytes is typically around 10... -4 ~10 -2 To further improve ionic conductivity, researchers have proposed preparing high-entropy sulfide solid-state electrolytes (S / cm). High-entropy solid-state electrolytes introduce multiple elements with highly random distribution at equivalent lattice positions in the crystal structure, inducing synergistic effects and structural distortions to form a single-phase solid solution structure with high configurational entropy, which significantly improves the ionic conductivity of solid-state electrolytes. In addition, high-entropy sulfides can significantly enhance the stability of the electrolyte / electrode interface through the synergistic effect of multiple anions. High-entropy sulfides can form a stable mixed conductive interface layer in situ at the lithium metal interface, which can uniformly dissipate lithium ions, thereby suppressing lithium dendrite growth and ultimately achieving an effective improvement in the electrochemical performance of all-solid-state batteries. Therefore, high-entropy sulfide solid-state electrolytes are currently a key focus of research.

[0004] Currently, the main methods for preparing high-entropy sulfide solid electrolytes include solid-phase reaction, high-energy ball milling, and liquid-phase methods. The solid-phase reaction method uses heat to provide sintering power at temperatures below the melting points of the components, involving particle rearrangement, grain boundary movement, and pore removal, achieving atomic-level reaction and crystallization in a dry process. The core of this method is to avoid solvent involvement, directly utilizing mechanical and thermal energy to drive the reaction of solid raw materials, forming a dense solid electrolyte with higher mechanical strength and ionic conductivity. However, high-entropy solid electrolytes prepared by the solid-phase reaction method have certain limitations, such as incomplete reaction of solid raw materials leading to low phase purity.

[0005] High-energy ball milling uses mechanical energy to drive the mixing and reaction of solid raw materials at the atomic level. The core of this method lies in utilizing the kinetic energy generated by the collision of high-speed grinding balls within the mill jar to break and recombine the chemical bonds in the raw materials, forming amorphous or crystalline sulfide solid electrolytes. However, high-energy ball milling is difficult to implement on a large scale, and the resulting solid electrolytes may exhibit component segregation and uneven particle size distribution, leading to fluctuations in conductivity.

[0006] The liquid-phase method involves dissolving raw materials in a polar organic solvent, where a chemical reaction occurs in a liquid environment to generate a sulfide solid electrolyte precursor. The final product is then obtained through solvent evaporation and heat treatment. The core of this method lies in utilizing the molecular-level dispersing ability of the solvent to achieve uniform mixing of the raw materials, avoiding the particle agglomeration problem of the solid-phase method and improving product uniformity. However, the liquid-phase method suffers from incomplete evaporation, leading to residual organic solvents. This can alter the electrolyte structure, creating pores that significantly reduce density and affect ionic conductivity.

[0007] Based on the above analysis, the existing preparation methods still have certain limitations. Some methods result in the formation of impurity phases or component segregation due to insufficient reaction, while others cause a decrease in the ionic conductivity and structural damage of the solid electrolyte due to the residual liquid phase during the reaction.

[0008] Therefore, how to improve the preparation method and obtain a high-entropy sulfide solid electrolyte with high phase purity, high ionic conductivity and good interfacial stability is an urgent problem to be solved at this stage, which is of great significance for the development of the next generation of high-performance all-solid-state batteries.

[0009] It should be noted that this section is intended to provide background or context for the technical solutions of this disclosure as set forth in the claims. The description herein does not constitute an admission that it is prior art simply because it is included in this section. Summary of the Invention

[0010] The purpose of this invention is to provide a high-entropy sulfide solid electrolyte and its preparation method, thereby overcoming, to at least to some extent, one or more problems caused by the limitations and defects of related technologies.

[0011] This invention first provides a high-entropy sulfide solid electrolyte, which includes the following two types: Type 1: High-entropy lithium-silver-germanium ore type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λWherein, X is any one or more of Ge, Si, Sn, and Al; Y is any one or more of P, Sb, As, and Bi; M is any one or more of S, O, and Se; and N is any one or more of F, Cl, Br, and I. The chemical formula satisfies the following conditions: θ + 4α + 5β - 2γ - λ = 0, 6 ≤ θ ≤ 7, 0 ≤ α ≤ 1, 0 ≤ β ≤ 1, α + β = 1, 4 ≤ γ ≤ 6, 0 ≤ λ ≤ 2, γ + λ = 6; Type 2: High-entropy lithium-germanium-phosphorus-sulfur type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λ Wherein, X is any one or more of Ge, Si, Al and Sn, Y is any one or more of P, Sb, As and Bi, M is any one or more of S, O and Se, and N is any one or more of F, Cl, Br and I; and the chemical formula satisfies the following conditions: θ+4α+5β-2γ-λ=0, 9.54≤θ<10.5, 1≤α≤2, 9.96≤γ≤12, γ+λ=12.

[0012] In this invention, the high-entropy sulfide solid electrolyte is Li 9.54 [Si 0.4 Ge 0.4 Sn 0.2 ] 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 Li 9.54 Ge 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 Li6PS 4.4 ClSe 0.6 or Li6Sb 0.1 P 0.9 S5I.

[0013] The present invention further provides a method for preparing a high-entropy sulfide solid electrolyte, comprising the following steps: S1, weighing Li source compound, X source compound, Y source compound, M source compound and N source compound according to stoichiometric ratio, grinding them to obtain a mixed precursor, and ball milling the mixed precursor in a ball mill for 5~30 minutes. S1. After ball milling, the mixed precursor is separated; S2. The mixed precursor after ball milling is weighed and subjected to unidirectional pressing to obtain cold-pressed mixed precursor sheets. The cold pressing operation is repeated to obtain 30-100 cold-pressed mixed precursor sheets; S3. The cold-pressed mixed precursor sheets are placed in a quartz tube, vacuumed, sealed, and then subjected to staged sintering: first, the temperature is increased to 100-200℃ at 2℃ / min and held for 3-5h; then, the temperature is increased to 200-300℃ at 3℃ / min and held for 5-10h; finally, the temperature is increased to 500-600℃ at 5℃ / min and held for 10-24h; S4. The quartz tube containing the cold-pressed mixed precursor sheets is rapidly cooled at a rate of 30-300℃ / min; S5. The cold-pressed mixed precursor sheets are removed from the cooled quartz tube and then ground to obtain a high-entropy sulfide solid electrolyte.

[0014] In this invention, in S1, the Li source compounds include: LiBr, Li2S, LiCl, and Li2O, etc.; the X source compounds include: SiS2, SnS2, SiSe2, and AlCl3, etc.; the Y source compounds include: P, P2S5, SbS2, and Bi2O3, etc.; the M source compounds include: S, Li2S, SiO2, and Sb2Se3, etc.; and the N source compounds include: LiCl, LiBr, LiI, and LiF, etc.

[0015] In this invention, in S1, the ball milling speed is 200~1000 rpm.

[0016] In this invention, in step S2, the pressing pressure is 100~400 MPa and the pressing time is 2~10 min.

[0017] In this invention, during step S4, at the end of cooling, the temperature of the high-entropy sulfide solid electrolyte is -20 to 50°C.

[0018] In this invention, the quenching medium used in S4 includes: liquid nitrogen, salt bath, oil bath and ice-water mixture.

[0019] The technical solution provided by this invention can include the following beneficial effects: A high-entropy sulfide solid electrolyte and its preparation method, employing a synergistic process of stepped sintering and rapid quenching after sintering, successfully prepares a high-entropy single-phase solid solution possessing both high ionic conductivity and high interfacial stability. Multiple solid precursor sources are thoroughly mixed by high-energy ball milling and then subjected to stepped solid-phase sintering in a sealed environment. The sintering process utilizes multi-stage heating and holding processes to ensure that each precursor source component is heated uniformly and reacts fully at each temperature control stage, thereby effectively promoting the formation of the high-entropy single-phase solid solution. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] Figure 1 is a flowchart of the preparation method of the high-entropy sulfide solid electrolyte in this invention; Figure 2 is the EIS test diagram of the solid electrolyte after quenching in this invention; Figure 3 is the EIS test diagram of the solid electrolyte cooled in the furnace in this invention; Figure 4 is a comparison diagram of XRD patterns of solid electrolytes without and without quenching in this invention; Figure 5 is the lithium deposition / stripping cycle curve of the symmetric battery after quenching in this invention; Figure 6 is the lithium deposition / stripping cycle curve of the symmetric battery cooled in the furnace in this invention; Figure 7 is the first charge-discharge specific capacity diagram of the all-solid battery after quenching in this invention; Figure 8 is the first charge-discharge specific capacity diagram of the all-solid battery cooled in the furnace in this invention. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0023] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0024] This example embodiment first provides a high-entropy sulfide solid electrolyte, which includes the following two types: Type 1: High-entropy lithium-sulfur silver-germanium ore type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λ Wherein, X is any one or more of Ge, Si, Sn, and Al; Y is any one or more of P, Sb, As, and Bi; M is any one or more of S, O, and Se; and N is any one or more of F, Cl, Br, and I. The chemical formula satisfies the following conditions: θ + 4α + 5β - 2γ - λ = 0, 6 ≤ θ ≤ 7, 0 ≤ α ≤ 1, 0 ≤ β ≤ 1, α + β = 1, 4 ≤ γ ≤ 6, 0 ≤ λ ≤ 2, γ + λ = 6; Type 2: High-entropy lithium-germanium-phosphorus-sulfur type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λ Wherein, X is any one or more of Ge, Si, Al and Sn, Y is any one or more of P, Sb, As and Bi, M is any one or more of S, O and Se, and N is any one or more of F, Cl, Br and I; and the chemical formula satisfies the following conditions: θ+4α+5β-2γ-λ=0, 9.54≤θ<10.5, 1≤α≤2, 9.96≤γ≤12, γ+λ=12.

[0025] The high-entropy sulfide solid electrolyte in this embodiment is a high-entropy single-phase solid solution that combines high ionic conductivity and high interfacial stability. This example embodiment also provides a method for preparing the high-entropy sulfide solid electrolyte. Please refer to Figure 1. The preparation method includes the following steps: S1, weighing Li source compound, X source compound, Y source compound, M source compound and N source compound according to stoichiometric ratio, grinding them to obtain a mixed precursor, ball milling the mixed precursor in a ball mill for 5~30 h, and separating the mixed precursor after ball milling.

[0026] Among them, Li-source compounds include: LiBr, Li2S, LiCl and Li2O, etc.; X-source compounds include: SiS2, SnS2, SiSe2 and AlCl3, etc.; Y-source compounds include: P, P2S5, SbS2 and Bi2O3, etc.; M-source compounds include: S, Li2S, SiO2 and Sb2Se3, etc.; N-source compounds include: LiCl, LiBr, LiI and LiF, etc.

[0027] The raw materials need to be vacuum dried at 50~70℃ for 8~12 hours. The total amount of all raw materials can be weighed at one time, which can be 3~5g. They can be placed in an agate mortar and manually ground and mixed for 10~30 minutes, and then ball-milled at 200~1000 rpm. After ball milling, open the ball mill jar in the glove box and separate the mixed precursor from the ball mill beads.

[0028] S2, Weigh the mixed precursor after ball milling, and perform unidirectional pressing to obtain cold-pressed mixed precursor sheets. Repeat the cold pressing operation to obtain 30-100 cold-pressed mixed precursor sheets. The pressing pressure is 100-400 MPa, and the pressing time is 2-10 min.

[0029] The amount of precursor mixed in this step can be 50-100 mg per weighing. Pour the mixed precursor into a 10 mm diameter polytetrafluoroethylene mold for pressing.

[0030] S3. The cold-pressed mixed precursor sheet is placed in a quartz tube, vacuumed, sealed, and then subjected to staged sintering: first, the temperature is increased to 100℃~200℃ at 2℃ / min and held for 3~5h; then, the temperature is increased to 200℃~300℃ at 3℃ / min and held for 5~10h; finally, the temperature is increased to 500℃~600℃ at 5℃ / min and held for 10~24h.

[0031] Specifically, in this step, the bottom of the quartz tube is sealed, the cold-pressed mixing precursor sheet is added, and then the quartz tube is connected to a vacuum pump for evacuation, which is carried out to a vacuum level of 2×10⁻⁶. -4 pa~3×10 -4 The top of the quartz tube is then melted and necked to seal it. Afterward, the sealed quartz glass tube is placed in a box furnace for stepped sintering.

[0032] S4. The quartz tube containing the cold-pressed mixing precursor sheet is rapidly cooled at a rate of 30 ~ 300℃ / min, rapidly cooling the cold-pressed mixing precursor sheet to -20~50℃, such as 0℃, 10℃, 30℃, etc. The quenching media used, in descending order of cooling rate, are liquid nitrogen quenching, salt bath quenching, oil bath quenching, and ice-water mixture.

[0033] S5. The cold-pressed mixed precursor sheet is removed from the cooled quartz tube and then ground to obtain a high-entropy sulfide solid electrolyte. Specifically, after cooling, the quartz glass tube is removed, transferred to a glove box for crushing, and the mixed precursor sheet is removed and uniformly ground to obtain a high-entropy sulfide solid electrolyte.

[0034] This embodiment employs a synergistic process of stepped sintering and rapid quenching after sintering to successfully prepare a high-entropy single-phase solid solution exhibiting both high ionic conductivity and high interfacial stability. Multiple solid precursor sources were thoroughly mixed using high-energy ball milling and then subjected to stepped solid-phase sintering in a sealed environment. The sintering process utilizes multi-stage heating and holding processes to ensure that each precursor source component is heated uniformly and reacts fully at each temperature control stage, thereby effectively promoting the formation of the high-entropy single-phase solid solution.

[0035] From a thermodynamic perspective, the disordered occupancy of multiple components generates high configurational entropy. This high configurational entropy (-TΔS) dominates the Gibbs free energy (ΔG = ΔH - TΔS) at high temperatures, effectively offsetting the adverse contribution of the mixing enthalpy (ΔH). This keeps the free energy of the single-phase solid solution lower than that of the multiphase separated state. This process follows the principle of minimizing Gibbs free energy at isothermal and isobaric conditions. By stabilizing the single-phase structure through high configurational entropy, the thermodynamic stability of the system is significantly improved. Upon entering the cooling stage, the decreasing temperature gradually increases the influence of the mixing enthalpy on the Gibbs free energy, raising the convex hull energy and leading to a thermodynamically metastable state. At this point, a rapid quenching process is employed to suppress atomic diffusion and migration through kinetic means, locking the homogeneous single-phase state at high temperature to room temperature, thus effectively preventing the formation of impurity phases. It is worth noting that increasing the number of components improves thermodynamic stability but also increases the kinetic hindrance to atomic diffusion; therefore, the required cooling rate increases with the number of components.

[0036] This invention effectively suppresses the formation of insulating impurity phases and reduces their obstruction to ion transport by employing a synergistic approach of thermodynamically forming a high-entropy stable single-phase structure and kinetically rapid quenching to inhibit diffusion. This not only significantly improves the ionic conductivity of the high-entropy sulfide solid electrolyte but also substantially enhances its interfacial stability, ultimately achieving a significant improvement in the electrochemical performance of all-solid-state batteries.

[0037] The following specific experimental examples illustrate the preparation method of this application.

[0038] Experimental Example 1: Preparation of Li 9.54 [Si 0.4 Ge 0.4 Sn 0.2 ] 1.74 P 1.44 S 11.1 Br 0.3 O 0.6Solid electrolyte (1) The required powders of Li2S, Ge, P, S, SiS2, SnS2, LiBr, Se, P2O5 and SbS2 were vacuum dried at 50°C for 8 h; (2) 3 g of powders of Li2S, Ge, P, S, SiS2, SnS2, LiBr, Se, P2O5 and SbS2 were weighed according to the above stoichiometric ratio, and then placed in an agate mortar and manually ground and mixed for 15 min; (3) The mixed precursor obtained in (2) was placed in a ball mill jar and ball milled at 500 rpm in a planetary ball mill for 24 h; (4) After ball milling, the ball mill jar was opened in the glove box and the mixed precursor synthesized in (3) was separated from the ball milling beads; (5) 100 mg of the mixed precursor in (4) was weighed, poured into a polytetrafluoroethylene mold with a diameter of 10 mm, and placed on a tablet press and subjected to 300 rpm. The product is subjected to unidirectional pressing at MPa pressure for 8 minutes to obtain a cold-pressed mixed precursor sheet. Step (5) is repeated to obtain a total of 30 cold-pressed mixed precursor sheets. Step (6) involves transferring the cold-pressed mixed precursor sheets obtained in step (5) into a bottom-sealed quartz glass tube, then connecting the quartz tube to a vacuum pump and evacuating to a vacuum level of 2.5 × 10⁻⁶. -4 pa, and then the top of the quartz tube is sintered and necked to seal; (7) the sealed quartz glass tube is placed in a box furnace for stepped sintering. First, the temperature is raised to 150℃ at 2℃ / min and held for 5 h; then the temperature is raised to 250℃ at 3℃ / min and held for 8 h; finally, the temperature is raised to 550℃ at 5℃ / min and held for 15 h; (8) the quartz tube in (7) is placed in liquid nitrogen quenching medium and cooled at a rate of about 200℃ / min to rapidly cool it to 25℃; (9) after cooling, the quartz glass tube is taken out, transferred to a glove box for crushing, the mixed precursor sheet is taken out, and uniformly ground to obtain Li 9.54 [Si 0.4 Ge 0.4 Sn 0.2 ] 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 High-entropy sulfide solid electrolyte.

[0039] Experimental Example 2: Preparation of Li 9.54 Ge 1.74 P 1.44 S 11.1 Br 0.3 O 0.6Solid electrolyte (1) The required powders such as Li2S, Ge, P, S, LiBr and P2O5 are vacuum dried at 50°C for 8 h; (2) 3g of powders such as Li2S, Ge, P, S, LiBr and P2O5 are weighed according to the above stoichiometric ratio, and then placed in an agate mortar and manually ground and mixed for 15 min; (3) The mixed precursor obtained in (2) is placed in a ball mill jar and ball milled at 500 rpm in a planetary ball mill for 24 h; (4) After ball milling, the ball mill jar is opened in the glove box and the mixed precursor synthesized in (3) is separated from the ball milling beads; (5) 100 mg of the mixed precursor in (4) is weighed, poured into a polytetrafluoroethylene mold with a diameter of 10 mm, placed on a tablet press and subjected to a pressure of 250 MPa for unidirectional pressing, and the holding time is 5 min to obtain a cold-pressed mixed precursor tablet. Repeat step (5) to obtain a total of 30 cold-pressed mixed precursor sheets; (6) transfer the cold-pressed mixed precursor sheets obtained in step (5) into a quartz glass tube with a sealed bottom, and then connect the quartz tube to a vacuum pump to evacuate to a vacuum level of 2.5 × 10⁻⁶. -4 pa, and then the top of the quartz tube is sintered and necked to seal; (7) the sealed quartz glass tube is placed in a box furnace for stepped sintering. First, the temperature is raised to 150℃ at 2℃ / min and held for 5 h; then the temperature is raised to 250℃ at 3℃ / min and held for 8 h; finally, the temperature is raised to 550℃ at 5℃ / min and held for 12 h; (8) the quartz tube in (7) is placed in a salt bath quenching medium and the cooling rate is about 100℃ / min to cool it rapidly to 25℃; (9) after cooling, the quartz glass tube is taken out, transferred to a glove box for crushing, the mixed precursor sheet is taken out, and uniformly ground to obtain Li 9.54 Ge 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 High-entropy sulfide solid electrolyte.

[0040] Preparation of Li6PS in Experiment Example 3 4.4 ClSe 0.6Solid electrolyte (1) The required powders of Li2S, P, S, LiCl and Se are vacuum dried at 50°C for 10 h; (2) 3g of powders of Li2S, P, S, LiCl and Se are weighed according to the above stoichiometric ratio, and then placed in an agate mortar and manually ground and mixed for 15 min; (3) The mixed precursor obtained in (2) is placed in a ball mill jar and ball milled at 500 rpm in a planetary ball mill for 12 h; (4) After ball milling, the ball mill jar is opened in the glove box and the mixed precursor synthesized in (3) is separated from the ball milling beads; (5) 100 mg of the mixed precursor in (4) is weighed, poured into a polytetrafluoroethylene mold with a diameter of 10 mm, placed on a tablet press and subjected to a pressure of 250 MPa for unidirectional pressing, and the holding time is 5 min to obtain a cold-pressed mixed precursor tablet. Repeat step (5) to obtain a total of 30 cold-pressed mixed precursor sheets; (6) transfer the cold-pressed mixed precursor sheets obtained in step (5) into a quartz glass tube with a sealed bottom, and then connect the quartz tube to a vacuum pump to evacuate to a vacuum level of 2.5 × 10⁻⁶. -4 pa, and then the top of the quartz tube is sintered and necked to seal; (7) the sealed quartz glass tube is placed in a box furnace for stepped sintering. First, the temperature is raised to 150℃ at 2℃ / min and held for 3 h; then the temperature is raised to 250℃ at 3℃ / min and held for 5 h; finally, the temperature is raised to 550℃ at 5℃ / min and held for 10 h; (8) the quartz tube in (7) is placed in an oil bath quenching medium and the cooling rate is about 60℃ / min to rapidly cool it to 25℃; (9) after cooling, the quartz glass tube is taken out, transferred to a glove box for crushing, the mixed precursor sheet is taken out, and uniformly ground to obtain Li6PS. 4.4 ClSe 0.6 High-entropy sulfide solid electrolyte.

[0041] Example 4: Preparation of Li6Sb 0.1 P 0.9S5I solid electrolyte (1) The required powders of Li2S, P, S, SbS2, LiI and Se are vacuum dried at 50°C for 10 h; (2) 3g of powders of Li2S, P, S, SbS2, LiI and Se are weighed according to the above stoichiometric ratio, and then placed in an agate mortar and manually ground and mixed for 15 min; (3) The mixed precursor obtained in (2) is placed in a ball mill jar and ball milled at 500 rpm in a planetary ball mill for 24 h; (4) After ball milling, the ball mill jar is opened in the glove box and the mixed precursor synthesized in (3) is separated from the ball milling beads; (5) 100 mg of the mixed precursor in (4) is weighed, poured into a polytetrafluoroethylene mold with a diameter of 10 mm, placed on a tablet press and subjected to a pressure of 250 MPa for unidirectional pressing, and the holding time is 5 min to obtain a cold-pressed mixed precursor tablet. Repeat step (5) to obtain a total of 30 cold-pressed mixed precursor sheets; (6) transfer the cold-pressed mixed precursor sheets obtained in step (5) into a quartz glass tube with a sealed bottom, and then connect the quartz tube to a vacuum pump to evacuate to a vacuum level of 2.5 × 10⁻⁶. -4 pa, and then the top of the quartz tube is sintered and necked to seal; (7) the sealed quartz glass tube is placed in a box furnace for stepped sintering. First, the temperature is raised to 150℃ at 2℃ / min and held for 3 h; then the temperature is raised to 250℃ at 3℃ / min and held for 5 h; finally, the temperature is raised to 550℃ at 5℃ / min and held for 10 h; (8) the quartz tube in (7) is placed in an ice-water mixture quenching medium and the cooling rate is about 30℃ / min to rapidly cool it to 25℃; (9) after cooling, the quartz glass tube is taken out, transferred to a glove box for crushing, the mixed precursor sheet is taken out, and uniformly ground to obtain Li6Sb. 0.1 P 0.9 S5I high-entropy sulfide solid electrolyte.

[0042] In the comparative example, furnace cooling was used instead of rapid cooling in liquid nitrogen quenching medium in the cooling step, and the other steps were the same as in Experimental Example 1.

[0043] Figure 2 shows the electrochemical impedance spectroscopy (EIS) of the solid electrolyte in Experiment 1 after quenching with liquid nitrogen. The EIS value is 10.025 Ω, and its ionic conductivity is calculated to be 11.32 mS / cm. Figure 3 shows the EIS of the solid electrolyte in the comparative example treated with furnace cooling. The EIS value is 15.026 Ω, and its ionic conductivity is calculated to be 7.55 mS / cm. Comparing Figures 2 and 3, it can be seen that the quenching process used in this invention can significantly reduce the bulk impedance of the electrolyte and effectively improve its ionic conductivity. Furthermore, because the high-entropy sulfide solid electrolyte prepared in Experiment 1 has a large number of components, it forms more potential low-energy metastable phases, increasing the convexity energy of the system and significantly increasing the thermodynamic driving force for phase separation. Therefore, a larger cooling rate is required. Thus, this application uses liquid nitrogen as the medium for rapid quenching, which has a higher cooling rate.

[0044] Figure 4 shows the X-ray diffraction patterns of the solid electrolytes prepared in Experimental Example 1 and the comparative example. The patterns show that both possess typical LGPS crystal structure characteristics. Meanwhile, the diffraction pattern of Experimental Example 1 shows a significant reduction in impurity phase peaks and a higher intensity of main phase diffraction peaks, indicating that the electrolyte prepared by the process of this invention has superior phase purity and crystallinity.

[0045] Figure 5 shows the symmetric battery assembled using the solid electrolyte prepared in Example 1 at 0.1 mA / cm². 2 Lithium deposition / stripping cycle curves under constant current conditions; the battery can cycle stably for 430 hours. Figure 6 shows the symmetric battery assembled using the solid electrolyte prepared in the comparative example at 0.1 mA / cm². 2 The lithium deposition / stripping cycle curves under constant current conditions show that the battery can only cycle stably for 140 hours. Comparing Figures 5 and 6, it can be seen that the solid electrolyte prepared by the quenching process used in this invention exhibits good interfacial stability with the lithium metal anode, effectively suppressing lithium dendrite growth.

[0046] Figure 7 shows the first charge-discharge curves of the all-solid-state battery assembled using the electrolyte from Example 1, with a first-cycle charge specific capacity of 180 mAh / g and a discharge specific capacity of 138 mAh / g. Figure 8 shows the first charge-discharge curves of the all-solid-state battery assembled using the comparative electrolyte, with a first-cycle charge specific capacity of 130 mAh / g and a discharge specific capacity of 96 mAh / g. This demonstrates that the solid-state electrolyte prepared in this invention can be used to construct all-solid-state batteries with excellent electrochemical performance.

[0047] In summary, this invention requires fewer pieces of equipment, is easy to operate, and is suitable for large-scale industrial production. The invention employs stepped sintering to achieve uniform heating and full reaction among the components of the precursor source, effectively promoting the formation of a high-entropy single-phase solid solution. Rapid quenching after stepped solid-phase sintering locks in the metastable solid solution structure obtained at high temperatures, effectively suppressing the formation of impurity phases during cooling and significantly improving the phase purity of the solid electrolyte. Through a dual strategy of thermodynamic and kinetic synergy—utilizing high configurational entropy to stabilize the single-phase structure and combining rapid quenching to suppress elemental diffusion—this invention effectively suppresses the formation of impurity phases, thereby significantly improving the ionic conductivity of the material. The high-entropy sulfide solid electrolyte prepared by this invention has an ionic conductivity as high as 11.32 mS / cm.

[0048] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A high-entropy sulfide solid electrolyte, characterized in that, The high-entropy sulfide solid electrolyte includes the following two types: Type 1: High-entropy lithium-sulfur silver-germanium ore type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λ Wherein, X is any one or more of Ge, Si, Sn, and Al; Y is any one or more of P, Sb, As, and Bi; M is any one or more of S, O, and Se; and N is any one or more of F, Cl, Br, and I. The chemical formula satisfies the following conditions: θ + 4α + 5β - 2γ - λ = 0, 6 ≤ θ ≤ 7, 0 ≤ α ≤ 1, 0 ≤ β ≤ 1, α + β = 1, 4 ≤ γ ≤ 6, 0 ≤ λ ≤ 2, γ + λ = 6; Type 2: High-entropy lithium-germanium-phosphorus-sulfur type solid electrolyte, the chemical formula of which is: Li θ X α Y β M γ N λ Wherein, X is any one or more of Ge, Si, Al and Sn, Y is any one or more of P, Sb, As and Bi, M is any one or more of S, O and Se, and N is any one or more of F, Cl, Br and I; and the chemical formula satisfies the following conditions: θ+4α+5β-2γ-λ=0, 9.54≤θ<10.5, 1≤α≤2, 9.96≤γ≤12, γ+λ=12.

2. The high-entropy sulfide solid electrolyte and its preparation method according to claim 1, characterized in that, The high-entropy sulfide solid electrolyte is Li 9.54 [Si 0.4 Ge 0.4 Sn 0.2 ] 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 Li 9.54 Ge 1.74 P 1.44 S 11.1 Br 0.3 O 0.6 Li6PS 4.4 ClSe 0.6 or Li6Sb 0.1 P 0.9 S5I.

3. The method for preparing the high-entropy sulfide solid electrolyte as described in claim 1 or 2, characterized in that, Includes the following steps: S1, Weigh the Li-source compound, X-source compound, Y-source compound, M-source compound, and N-source compound according to stoichiometric ratio, grind them to obtain a mixed precursor, ball mill the mixed precursor in a ball mill for 5-30 h, and separate the mixed precursor after ball milling; S2, Weigh the mixed precursor after ball milling, perform unidirectional pressing to obtain cold-pressed mixed precursor sheets, repeat the cold pressing operation to obtain 30-100 S3, Place the cold-pressed mixed precursor sheet in a quartz tube, evacuate, seal, and then perform staged sintering: first, heat to 100℃~200℃ at 2℃ / min and hold for 3~5h; then heat to 200℃~300℃ at 3℃ / min and hold for 5~10h; finally, heat to 500℃~600℃ at 5℃ / min and hold for 10~24h; S4, Rapidly cool the quartz tube containing the cold-pressed mixed precursor sheet: the cooling rate is 30~300℃ / min; S5, Remove the cold-pressed mixed precursor sheet from the cooled quartz tube and then grind it to obtain a high-entropy sulfide solid electrolyte.

4. The method for preparing the high-entropy sulfide solid electrolyte according to claim 3, characterized in that, In S1, the Li source compounds include: LiBr, Li2S, LiCl and Li2O; the X source compounds include: SiS2, SnS2, SiSe2 and AlCl3; the Y source compounds include: P, P2S5, SbS2 and Bi2O3; the M source compounds include: S, Li2S, SiO2 and Sb2Se3; and the N source compounds include: LiCl, LiBr, LiI and LiF.

5. The method for preparing the high-entropy sulfide solid electrolyte according to claim 3, characterized in that, In S1, the ball milling speed is 200~1000 rpm.

6. The method for preparing the high-entropy sulfide solid electrolyte according to claim 3, characterized in that, In S2, the pressing pressure is 100~400 MPa, and the pressing time is 2~10 min.

7. The method for preparing the high-entropy sulfide solid electrolyte according to claim 3, characterized in that, In S4, at the end of cooling, the temperature of the high-entropy sulfide solid electrolyte is -20~50℃.

8. The method for preparing the high-entropy sulfide solid electrolyte according to any one of claims 3 to 7, characterized in that, The quenching media used in S4 include liquid nitrogen, salt bath, oil bath, and ice-water mixture.

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