Sulfide solid electrolytes, their manufacturing methods, and applications

Abstract

This invention presents a sulfide solid electrolyte, a method for producing the same, and its applications. [Solution] The molecular formula of the above sulfide solid electrolyte is LiaP1-bMbScOdXe, where 5

Description

[Technical Field]

[0001] This invention relates to the field of lithium-ion batteries, and more specifically to sulfide solid electrolytes, methods for producing the same, and applications. [Background technology]

[0002] In recent years, with the rapid development of electric vehicles and large-scale energy storage systems, the demand for all-solid-state lithium batteries, which offer high energy density and high safety, has been steadily increasing. Sulfide solid electrolytes are considered one of the most promising candidate materials for all-solid-state lithium batteries due to their advantages such as high ionic conductivity, a wide electrochemical window, and good machinability. Synthesis methods for sulfide solid electrolytes mainly include solid-phase sintering, mechanical ball milling, and liquid-phase methods. Among these, solid-phase sintering and mechanical ball milling are currently the most widely used manufacturing methods due to their relatively simple processes.

[0003] However, in actual manufacturing, sulfur readily volatilizes at high temperatures, and the large reaction barrier in solid-phase reactions makes it difficult to completely avoid the formation of impurity phases such as Li2S, LiCl, and P. This significantly reduces the ionic conductivity of sulfide solid electrolytes and affects their electrochemical stability. While using excess sulfur can reduce sulfur loss, it can lead to the formation of new impurity phases and increased safety hazards, making it difficult to balance performance and cost. Doping can improve the ionic conductivity of sulfide solid electrolytes, but there is a lack of systematic theoretical guidelines regarding the selection of doping elements and the optimization of doping amounts, and the mechanism by which doping affects phase purity and electrochemical performance is still not fully understood. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention proposes a sulfide solid electrolyte, a method for producing the same and an application thereof. The sulfide solid electrolyte, the method for producing the same and the application thereof provided by the present invention allow obtaining a high-purity doped sulfide solid electrolyte, can reduce irreversible lithium ion consumption and reduction in Coulombic efficiency caused by impurities, reduce these side reactions and improve Coulombic efficiency, thereby improving the energy efficiency, cycle performance and the like of lithium ion batteries. [Means for Solving the Problem]

[0005] In order to solve the above technical problem, the present invention provides a sulfide solid electrolyte. The molecular formula of said sulfide solid electrolyte is Li a P 1-b M b S c O d X e , wherein 5<a<10, 0<b<1, 0<c<6, 0<d<2.5, 4<c+d<6, 0<e<2; M is one or more selected from the group consisting of Al, Ga, In, Ti, Sc, As, Sb, Bi, V, Nb, Ca, Mg, Sr, Ba, Zn, Cr, Sn and Pb, X is one or more selected from the group consisting of Cl, Br and I, and in the X-ray diffraction pattern of said sulfide solid electrolyte powder obtained by CuKα radiation, no diffraction peak appears in the ranges of 27° to 27.3°, 29° to 29.5° and 35° to 35.2°.

[0006] In one embodiment of the present invention, M is one or more selected from the group consisting of Sb, In, Bi and Mg, and X is selected from Cl.

[0007] In one embodiment of the present invention, the value range of b is 0<b≦0.1.

[0008] In one embodiment of the present invention, the purity of said sulfide solid electrolyte exceeds 99%.

[0009] The present invention further provides The process involves mixing Li, P, M, S, and X sources in stoichiometric ratios according to the chemical formula of a sulfide solid electrolyte, followed by polishing to obtain a sulfide solid electrolyte precursor powder. The above sulfide solid electrolyte precursor powder is subjected to calcination treatment to obtain the above sulfide solid electrolyte, The present invention provides a method for producing the above-mentioned sulfide solid electrolyte containing [the specified substance].

[0010] In one embodiment of the present invention, the Li source is one or more selected from LiCl, LiBr, LiI, or Li2S; the P source is one or more selected from the element P, P2S5, P4S6, PCl5, or PBr5; the M source is one or more selected from oxides of M or sulfides of M; and the S source is one or more selected from sulfides of the element S, Li2S, P2S5, P4S6, or M. The sulfide of M comprises one or more selected from As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3, Sc2S3, MgS, CaS, SrS, BaS, ZnS, CrS, SnS, or PbS; the above X source is one or more selected from LiCl, PCl5, LiBr, PBr5, LiI, or I2; and the element O in the chemical formula is derived from an oxide of M.

[0011] In one embodiment of the present invention, the polishing time is 1 to 48 hours, the polishing speed is 50 rpm to 1500 rpm, and the ball-to-material ratio is 1:1 to 100:1.

[0012] In one embodiment of the present invention, the temperature of the firing process is 400°C to 600°C, and the duration of the firing process is 1 hour to 24 hours.

[0013] The present invention further states that, at least, Positive electrode sheet and Negative electrode sheet and Displaced between the adjacent positive electrode sheet and the negative electrode sheet, a solid electrolyte membrane containing the sulfide solid electrolyte, We provide an all-solid-state lithium-ion battery that includes [the specified component].

[0014] The present invention also provides an electronic device comprising the above-mentioned all-solid-state lithium-ion battery. [Effects of the Invention]

[0015] In summary, the present invention presents a sulfide solid electrolyte, a method for producing the same, and its applications. By controlling the type of raw materials used in the synthesis of the sulfide solid electrolyte, nucleation of the sulfide solid electrolyte can be promoted, the grain growth direction and rate can be controlled, resulting in more uniform particle size, improved crystallinity, reduced impurity phases at grain boundaries, and improved phase purity. Simultaneously, by selecting the synthesis raw materials, the thermodynamic and kinetic conditions of the reaction can be changed, enabling thermodynamic and dynamical control. This lowers the Gibbs free energy for impurity phase formation, making it easier for the reaction to produce the crystalline phase of the sulfide solid electrolyte, improving the rate of production of the target product, and suppressing the formation of impurity phases. By introducing specific doping elements and optimizing the doping amount, the formation of impurity phases such as Li2S, LiCl, and P can be effectively suppressed, resulting in a high-purity sulfide solid electrolyte, and improving the air stability and chemical stability of the sulfide solid electrolyte. High-purity doped sulfide solid electrolytes can be obtained, reducing irreversible lithium-ion consumption and Coulomb efficiency degradation caused by impurities. These side reactions are reduced, Coulomb efficiency is improved, and thereby the energy efficiency and cycle performance of lithium-ion batteries can be improved. [Brief explanation of the drawing]

[0016] To more clearly illustrate embodiments of the present invention or technical solutions in the prior art, the drawings used in describing embodiments or the prior art are briefly introduced below. Clearly, the drawings described below represent only a portion of embodiments of the present invention. Those skilled in the art can obtain other drawings based on these without any creative effort. [Figure 1] This is the X-ray diffraction pattern of the sulfide solid electrolyte in Example 3. [Figure 2]is an X-ray diffraction pattern of the sulfide solid electrolyte in Example 11. [Figure 3] is an X-ray diffraction pattern of the sulfide solid electrolyte in Example 12. [Figure 4] is an X-ray diffraction pattern of the sulfide solid electrolyte in Example 13. [Figure 5] is an X-ray diffraction pattern of the sulfide solid electrolyte in Comparative Example 1. [Figure 6] is an X-ray diffraction pattern of the sulfide solid electrolyte in Comparative Example 4. MODE FOR CARRYING OUT THE INVENTION

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can readily understand other advantages and effects of the present invention from the content disclosed in the present specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] It should be understood that the present invention can be embodied in various forms and should not be construed as limited to the embodiments set forth herein; rather, by providing these embodiments, the disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0019] The technical solution of the present invention will be described in further detail below with reference to several embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] The present invention provides a sulfide solid electrolyte. The molecular formula of the sulfide solid electrolyte is Li a P 1-b M b Sc O d X e wherein 5<a<10, 0<b<1, 0<c<6, 0<d<2.5, 4<c+d<6, 0<e<2; M is one or more selected from the group consisting of Al, Ga, In, Ti, Sc, As, Sb, Bi, V, Nb, Ca, Mg, Sr, Ba, Zn, Cr, Sn and Pb, and X is one or more selected from the group consisting of Cl, Br and I. Herein, the purity of the sulfide solid electrolyte exceeds 99% for example, and in an X-ray diffraction (XRD) pattern of the sulfide solid electrolyte powder obtained by CuKα radiation, no diffraction peak appears in the ranges of 27° to 27.3°, 29° to 29.5° and 35° to 35.2°, that is, no diffraction peak of Li2S appears in the range of 27° to 27.3°, no diffraction peak of P appears in the range of 29° to 29.5°, and no diffraction peak of LiCl appears in the range of 35° to 35.2°. That is, the present invention can obtain a high-purity doped sulfide solid electrolyte, can reduce irreversible lithium ion consumption and reduction in coulombic efficiency caused by impurities, reduce these side reactions and improve coulombic efficiency, thereby improving the energy efficiency, cycle performance and the like of lithium ion batteries.

[0021] In one embodiment of the present invention, M is one or more selected from, for example, Sb, In, Bi and Mg, and the ionic radii of these elements are close to the ionic radii of host elements such as sulfur and phosphorus in the sulfide solid electrolyte. Therefore, M can more easily replace the positions of the host elements during doping without causing excessive lattice strain. Furthermore, elements such as Sb, In, Bi, or Mg can form stable chemical bonds with sulfur elements in the sulfide, and are not easily destroyed by external influences. This can effectively improve the air stability of the sulfide solid electrolyte, improve the air stability and chemical stability of the sulfide solid electrolyte, improve the cycle stability and performance of the battery, and improve the practicability and reliability of the sulfide solid electrolyte.

[0022] In one embodiment of the present invention, X is selected as a halogen element. Depending on the halogen, the degree of anion disorder between the 4a site and 4c site in the crystal structure of the sulfide solid electrolyte varies from a small number of antisite defects when X is I to 60% site disorder when X is Cl. The lithium conductivity of these compounds mainly depends on the degree of disorder occupied by anion sites and cation sites. Therefore, X can be selected as Cl, for example, which can improve the ionic conductivity and electrochemical stability of the sulfide solid electrolyte, and improve the voltage stability. The value range of b is 0 < b ≤ 0.1. If the doping amount is too low, an effective dielectric layer may not be formed between the electrolyte and the lithium metal anode. Excessive doping amount causes excessive lattice strain, destroys the original crystal structure, leads to a decrease in the structural stability of the material, further causes phase separation and amorphization, and may lead to a decrease in the ionic conductivity of the material. In a specific embodiment of the present invention, in order to improve the cycle performance of the lithium-ion battery, when M is a +5-valent element, the optimal value of b is 0.04; when M is a +3-valent element, the optimal value of b is 0.02; and when M is a +2-valent element, the optimal value of b is 0.02.

[0023] The present invention further provides a method for producing a sulfide solid electrolyte. The method at least comprises: after mixing a Li source, a P source, an M source, an S source and an X source in a stoichiometric ratio according to the chemical formula of the sulfide solid electrolyte, performing a grinding treatment to obtain a sulfide solid electrolyte precursor powder; and calcining the sulfide solid electrolyte precursor powder to obtain the sulfide solid electrolyte.

[0024] In one embodiment of the present invention, the chemical formula of the sulfide solid electrolyte is Li a P 1-b M b S c O d X eAccordingly, the Li source, P source, M source, S source and X source are uniformly mixed in stoichiometric ratios. Here, the Li source is one or more selected from, for example, LiCl, LiBr, LiI or Li2S, the P source is one or more selected from, for example, the element P, P2S5, P4S6, PCl5 or PBr5, the M source is one or more selected from the oxide of M or the sulfide of M, the S source is one or more selected from the sulfide of the element S, Li2S, P2S5, P4S6 or M, and the sulfide of M is The doped material contains one or more selected from As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3, Sc2S3, MgS, CaS, SrS, BaS, ZnS, CrS, SnS, or PbS, and the X source is one or more selected from LiCl, PCl5, LiBr, PBr5, LiI, or I2, and the O element in the chemical formula is derived from an oxide of M. After uniformly mixing the raw materials, for example, the raw materials are placed in a ball mill container and ground in a ball mill under an inert gas atmosphere. Here, the ball-to-raw ratio is, for example, 1:1 to 100:1, the grinding speed is, for example, 50 rpm to 1500 rpm, and the grinding time is, for example, 1 hour to 48 hours, and a sulfide solid electrolyte precursor powder can be obtained. Since the doped material is an oxide or sulfide of M, its surface energy is high, and the surrounding Li + P5 + , and S2 - By attracting ions such as these, it is possible to promote nucleation of sulfide solid electrolytes, control the grain growth direction and rate, and achieve more uniform particle size, improved crystallinity, reduced impurity phases at grain boundaries, and improved phase purity.

[0025] In one embodiment of the present invention, a sulfide solid electrolyte precursor powder is subjected to calcination treatment. Here, the calcination temperature is, for example, 400°C to 600°C, and the calcination time is, for example, 1 hour to 24 hours, thereby obtaining a sulfide solid electrolyte. By doping with oxide M or sulfide M, the thermodynamic and kinetic conditions of the reaction are changed, and thermodynamic and kinetic control becomes possible. From a thermodynamic standpoint, the Gibbs free energy for impurity phase formation is reduced, making it easier for the reaction to produce a crystalline phase of the sulfide solid electrolyte. From a kinetic standpoint, the rate of formation of the target product is improved, the formation of the impurity phase is suppressed, and the purity of the resulting sulfide solid phase can be improved.

[0026] The present invention further provides an all-solid-state lithium-ion battery comprising a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane disposed between adjacent positive and negative electrode sheets. Here, the solid electrolyte membrane contains the sulfide solid electrolyte to improve the cycle characteristics of the all-solid-state lithium-ion battery. In one embodiment of the present invention, the solid electrolyte membrane is obtained, for example, by cold-pressing the sulfide solid electrolyte under a pressure of 300 MPa to 400 MPa, and the thickness of the solid electrolyte membrane is, for example, 100 μm to 500 μm. In the present invention, the all-solid-state lithium-ion battery is, for example, a primary battery or a secondary battery, and the secondary battery is, for example, a pouch-type battery, a hard-case-type battery, a cylindrical-type battery, etc. The present invention does not particularly limit the type or category of the all-solid-state lithium-ion battery.

[0027] In one embodiment of the present invention, the positive electrode sheet includes, for example, a positive electrode collecting fluid and a positive electrode active layer disposed on at least one side of the positive electrode collecting fluid. Here, the positive electrode collecting fluid is, for example, a foil formed by surface treatment with nickel, titanium, aluminum, silver, stainless steel, or carbon. In addition to foil, the positive electrode collecting fluid can be used in any one or more combinations of various forms such as film, mesh, porous, foam, or nonwoven fabric, and the thickness of the positive electrode collecting fluid is, for example, 8 μm to 15 μm.

[0028] In one embodiment of the present invention, the positive electrode active layer includes, for example, a positive electrode active material, a positive electrode electrolyte, a positive electrode conductive agent, and a positive electrode binder. Here, the positive electrode active material is at least one selected from, for example, lithium nickel cobalt manganese oxide (NCM), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), lithium cobalt oxide (LCO), or lithium nickel cobalt aluminum oxide (NCA). The positive electrode electrolyte is, for example, a halide solid electrolyte, and the positive electrode conductive agent is at least one selected from, for example, graphite, graphene, conductive carbon black (Super P), vapor-grown carbon fiber (VGCF), or carbon nanotubes.The positive electrode binder can be, for example, polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polymerized styrene butadiene rubber (SBR), polyvinyl pyrrolidone (PVP), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyurethane (PU), polyvinyl alcohol (PVA), or sodium alginate. Alginate (Alg), ethylene-propylene-diene monomer (EPDM), styrene-butadiene rubber, fluororubber, β-cyclodextrin polymer (β-CDp), polypropylene emulsion (LA132), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), fluorinated ethylene-propylene copolymer (FEP), perfluoroalkoxy resin (PFA), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE). It is at least one selected from polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) or polyvinylidene fluoride-trifluorochloroethylene copolymer (PVDF-CTFE), etc.

[0029] In one embodiment of the present invention, the positive electrode fluid collector is, for example, aluminum foil, and the positive electrode active material is, for example, LiNi0.8 Co 0.1 Mn 0.1 The positive electrode electrolyte is O2, and the positive electrode electrolyte is, for example, Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The positive electrode conductive agent includes, for example, Super P and VGCF, with a mass ratio of Super P to VGCF of, for example, 1:1, and the positive electrode binder is, for example, PTFE. The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are uniformly mixed in a mass ratio of, for example, 69:29:1:1, and then laminated with aluminum foil by dry pressing to obtain a positive electrode sheet. The present invention does not limit the mass ratio of the positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder, and can be selected according to actual requirements, and a positive electrode fluid collector may not be installed if necessary.

[0030] In one embodiment of the present invention, the negative electrode sheet is at least one selected from a lithium metal sheet, an indium metal sheet, or a lithium indium alloy sheet. In another embodiment of the present invention, the negative electrode sheet includes, for example, a negative electrode current collector and a negative electrode active layer coated on at least one surface of the negative electrode current collector. Here, the negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector, or a stainless steel current collector, and the thickness of the negative electrode current collector is, for example, 8 μm to 15 μm.

[0031] In one embodiment of the present invention, the negative electrode active layer includes, for example, a negative electrode active material, a negative electrode electrolyte, a negative electrode conductive agent, and a negative electrode binder. The negative electrode active material is at least one selected from graphite-based materials, silicon materials, or composite materials of graphite-based materials and silicon materials. The silicon material is at least one selected from, for example, silicon oxide materials or silicon carbide materials. The negative electrode electrolyte is, for example, the above-mentioned sulfide solid electrolyte. The negative electrode conductive agent is at least one selected from, for example, graphite, graphene, super P, VGCF, or carbon nanotubes. The negative electrode binder is at least one selected from, for example, PVDF, CMC, SBR, PVP, PMMA, PAN, PAA, PU, ​​PVA, Alg, EPDM, styrene-butadiene rubber, fluororubber, β-CDp, LA132, PTFE, ETFE, FEP, PFA, PCTFE, ECTFE, PVDF-HFP, or PVDF-CTFE.

[0032] In one embodiment of the present invention, the negative electrode collecting fluid is, for example, copper foil, and the negative electrode active material is, for example, a mixture of silicon oxide material and graphite, with a ratio of silicon oxide material to graphite of, for example, 5:95. The negative electrode electrolyte is, for example, the above-mentioned sulfide solid electrolyte. The negative electrode conductive agent includes, for example, super P and VGCF, with a mass ratio of super P to VGCF of, for example, 1:1. The negative electrode binder is, for example, SBR. The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are uniformly mixed in a mass ratio of, for example, 72:22:3:3, and then laminated with copper foil by dry pressing to obtain a negative electrode sheet. The present invention does not limit the mass ratio of the negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder, and can be selected according to actual requirements, and the negative electrode collecting fluid may not be installed if necessary.

[0033] In one embodiment of the present invention, a solid-state lithium-ion battery is obtained by sequentially stacking the positive electrode sheet, solid electrolyte membrane, and negative electrode sheet, and then pressurizing and sealing them. Here, the assembly process of the solid-state battery is completed in a glove box with an inert atmosphere.

[0034] The present invention will be described in more detail below based on embodiments, but the present invention is not limited to these embodiments. The present invention can be modified as appropriate without departing from the spirit of the invention, and all such modifications will fall within the technical scope of the present invention.

[0035] [Examples] Example 1 Preparation of sulfide solid electrolyte: Under an argon atmosphere, 2.015 mol of Li2S, 1.5 mol of LiCl, 0.495 mol of P2S5, and 0.01 mol of MgO were placed in a tungsten carbide ball mill container. Tungsten carbide balls were added in a ball-to-material ratio of 40:1. The ball mill was rotated at 100 rpm for 10 minutes, then at 800 rpm for 16 hours to obtain a uniformly mixed sulfide solid electrolyte precursor powder. The obtained sulfide solid electrolyte precursor powder was placed in a crucible and calcined at 500 °C for 10 hours. After cooling, Li 5.53 P 0.99 Mg 0.01 S 4.49 O 0.01 Cl 1.5 I obtained it. Preparation of solid electrolyte membrane: 50 mg Li 5.5 P 0.99 S 0.01 S 4.475 O 0.025 Cl 1.5 A solid electrolyte membrane with a thickness of 400 μm and a diameter of 10 mm was fabricated by cold pressing at 360 MPa. Cathode sheet fabrication: LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive agent, Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 A mixture of aluminum foil and PTFE was prepared in a mass ratio of 69:1:29:1. This mixture was laminated with aluminum foil by dry pressing and cut into circular sheets with a diameter of 10 mm to obtain a positive electrode sheet. Here, the positive electrode conductive material contains Super P and VGCF, and the mass ratio of Super P to VGCF is, for example, 1:1. Negative electrode sheet: A lithium element sheet was selected and cut into a circular sheet with a diameter of 10 mm to obtain the negative electrode. Assembly of the all-solid-state battery: The positive electrode sheet, solid electrolyte membrane, and negative electrode prepared above were stacked in order, pressurized, and sealed to assemble the all-solid-state lithium-ion battery.

[0036] Example 2 The chemical formula of the sulfide solid electrolyte prepared using 2.0225 mol Li2S, 1.5 mol LiCl, 0.4925 mol P2S5, and 0.015 mol MgO is Li 5.545 P 0.985 Mg 0.015 S 4.485 O 0.015 Cl 1.5 The other operations were the same as in Example 1.

[0037] Example 3 The chemical formula of the sulfide solid electrolyte prepared using 2.03 mol Li2S, 1.5 mol LiCl, 0.49 mol P2S5, and 0.02 mol MgO is Li 5.56 P 0.98 Mg 0.02 S 4.48 O 0.02 Cl 1.5 The other operations were the same as in Example 1.

[0038] Example 4 The chemical formula of the sulfide solid electrolyte prepared using 2.09 mol Li2S, 1.5 mol LiCl, 0.47 mol P2S5, and 0.06 mol MgO is Li 5.68 P 0.94 Mg 0.06 S 4.44 O 0.06 Cl 1.5 The other operations were the same as in Example 1.

[0039] Example 5 The chemical formula of the sulfide solid electrolyte prepared using 2.15 mol Li2S, 1.5 mol LiCl, 0.45 mol P2S5, and 0.1 mol MgO is Li 5.8 P 0.9 Mg 0.1 S 4.4 O 0.1 Cl1.5 Other operations were the same as those in Example 1.

[0040] Example 6 The chemical formula of the sulfide solid electrolyte prepared using 1.83 mol of Li2S, 1.9 mol of LiCl, 0.49 mol of P2S5 and 0.02 mol of MgO is Li 5.16 P 0.98 Mg 0.02 S 4.08 O 0.02 Cl 1.9 Other operations were the same as those in Example 1.

[0041] Example 7 The chemical formula of the sulfide solid electrolyte prepared using 2.53 mol of Li2S, 1 mol of LiCl, 0.49 mol of P2S5 and 0.02 mol of MgO is Li 6.06 P 0.98 Mg 0.02 S 4.98 O 0.02 Cl, and other operations were the same as those in Example 1.

[0042] Example 8 The chemical formula of the sulfide solid electrolyte prepared using 3.43 mol of Li2S, 0.1 mol of LiCl, 0.49 mol of P2S5 and 0.02 mol of MgO is Li 6.96 P 0.98 Mg 0.02 S 5.88 O 0.02 Cl 0.1 Other operations were the same as those in Example 1.

[0043] Example 9 The chemical formula of the sulfide solid electrolyte prepared using 2.03 mol of Li2S, 1.4 mol of LiCl, 0.1 mol of LiBr, 0.49 mol of P2S5 and 0.02 mol of MgO is Li 5.56 P 0.98 Mg 0.02 S 4.48 O 0.02 Cl 1.4 Br 0.1 Other operations were the same as those in Example 1.

[0044] Example 10 The chemical formula of the sulfide solid electrolyte prepared using 2.03 mol Li2S, 1.3 mol LiCl, 0.1 mol LiBr, 0.1 mol LiI, 0.49 mol P2S5, and 0.02 mol MgO is Li 5.56 P 0.98 Mg 0.02 S 4.48 O 0.02 Cl 1.3 Br 0.1 I 0.1 The other operations were the same as in Example 1.

[0045] Example 11 The core chemical formula of the sulfide solid electrolyte prepared using 2.02 mol Li2S, 1.5 mol LiCl, 0.49 mol P2S5, and 0.01 mol In2O3 is Li 5.54 P 0.98 In 0.02 S 4.47 O 0.03 Cl 1.5 The other operations were the same as in Example 1.

[0046] Example 12 The core chemical formula of the sulfide solid electrolyte prepared using 2.02 mol Li2S, 1.5 mol LiCl, 0.49 mol P2S5, and 0.01 mol Bi2O3 is Li 5.54 P 0.98 Bi 0.02 S 4.47 O 0.03 Cl 1.5 The other operations were the same as in Example 1.

[0047] Example 13 The core chemical formula of the sulfide solid electrolyte prepared using 2 mol Li2S, 1.5 mol LiCl, 0.48 mol P2S5, and 0.02 mol Sb2O5 is Li 5.5 P 0.96 S 0.04 S 4.40 O 0.10 Cl 1.5The other operations were the same as in Example 1.

[0048] Example 14 The core chemical formula of the sulfide solid electrolyte prepared using 2.03 mol Li2S, 1.5 mol LiCl, 0.49 mol P2S5, and 0.02 mol CaO is Li 5.56 P 0.98 Ca 0.02 S 4.48 O 0.02 Cl 1.5 The other operations were the same as in Example 1.

[0049] Example 15 The core chemical formula of the sulfide solid electrolyte prepared using 2.03 mol Li2S, 1.5 mol LiCl, 0.49 mol P2S5, and 0.02 mol ZnO is Li 5.56 P 0.98 Zn 0.02 S 4.48 O 0.02 Cl 1.5 The other operations were the same as in Example 1.

[0050] Comparative Example 1 The chemical formula of the sulfide solid electrolyte prepared using 2 mol of Li2S, 1.5 mol of LiCl, and 0.5 mol of P2S5 is Li 5.5 PS 4.5 Cl 1.5 The other operations were the same as in Example 1.

[0051] Comparative Example 2 The chemical formula of the sulfide solid electrolyte prepared using 2 mol Li2S, 1.4 mol LiCl, 0.1 mol LiBr, and 0.5 mol P2S5 is Li 5.5 PS 4.5 Cl 1.4 Br 0.1 The other operations were the same as in Example 1.

[0052] Comparative Example 3 The chemical formula of the electrolyte prepared using 2 mol Li2S, 1.3 mol LiCl, 0.1 mol LiBr, 0.1 mol LiI, and 0.5 mol P2S5 is Li 5.5 PS 4.5 Cl 1.3 Br 0.1 I 0.1 The other operations were the same as in Example 1.

[0053] Comparative Example 4 The chemical formula of the sulfide solid electrolyte prepared using 2.21 mol Li2S, 1.5 mol LiCl, 0.43 mol P2S5, and 0.14 mol MgO is Li 5.92 P 0.86 Mg 0.14 S 4.36 O 0.14 Cl 1.5 The other operations were the same as in Example 1.

[0054] In one embodiment of the present invention, the XRD test includes polishing and sieving a sulfide solid electrolyte powder material to prepare a powder material suitable for the XRD test, for example, a powder material that passes through a sieve of 60 to 200 mesh. The sieved powder is placed on a standard sample stage, packed, and flattened. The XRD detection angle range is set to 10° to 80°. The corresponding X-ray scanning speed can be set according to the model of the X-ray diffractometer, and is usually less than 15° / min, to obtain the XRD pattern.

[0055] In one embodiment of the present invention, the purity test includes adding a sulfide solid electrolyte to a closed-type high-pressure acid decomposition vessel containing, for example, nitric acid (HNO3) and hydrochloric acid (HCl). The volume ratio of HNO3 to HCl is, for example, 3:1. To promote the dissolution of the sulfide, a small amount of hydrofluoric acid (HF) is added, with the hydrofluoric acid content being, for example, 0.1% v / v. The above mixed solution is placed in a microwave decomposition vessel and decomposed at 200°C for 30 minutes, after which it is quickly transferred to a polytetrafluoroethylene container. The total molar amounts of Li, P, M, S, and X are measured using inductively coupled plasma mass spectrometry (ICP-MS), and each of the following values ​​is measured: Li , n P , n M , n S and n X This is how it is written. In the sulfide solid electrolyte, the impurities Li2S are y mol, LiCl is z mol, P is w mol, and the main phase is Li a P 1-b M b S c O d X eが Assuming there are x moles, the following system of equations holds:

number

number

[0056] In Examples 1-15 and Comparative Examples 1-4 of the present invention, lithium-ion batteries were fabricated using different sulfide solid electrolytes. The fabricated lithium-ion batteries were subjected to long-cycle charge-discharge at 25°C, and their discharge capacity was measured to calculate the energy density. Here, the operating voltage range for the battery test was 2.5V to 4.3V, and the charge-discharge rate was 1C / 1C. The discharge capacity of the first cycle was recorded as the 1C discharge capacity. The test was terminated when the battery capacity reached 80% of the capacity of the first cycle (80% State of Health, 80% SOH), and the number of cycles at room temperature was measured. For symmetrical batteries, the current density was 1 mA / cm². 2 A constant current charge-discharge cycle test was performed, and the results are shown in Table 1.

[0057] [Table 1]

[0058] As shown in Figures 1 to 5, a comparison of Examples 3, 11-13 and Comparative Examples 1 and 4 reveals that by doping with different M elements and controlling the amount of M doping, the sulfide solid electrolyte obtained in the present invention exhibits strong diffraction peaks at 2θ positions of 17.5±0.3°, 25.5±0.3°, 30.5±0.3°, and 32±0.3°, which are diffraction peaks of the (111), (220), (311), and (222) crystal planes, respectively. This indicates that doping with different elements M and using an optimal amount of M improves the crystal structure of the sulfide solid electrolyte and enhances ionic conductivity. This also indicates that doping with element M does not destroy the crystal structure of the sulfide solid electrolyte. As shown in Figure 5, the undoped Li of Comparative Example 1 5.5 PS 4.5 Cl 1.5 In the XRD pattern, the diffraction peak of Li2S appears at 27°, the diffraction peak of P appears at 29.1°, and the diffraction peak of LiCl appears at 35.1°. As shown in Figure 1-4, Li after doping 5.56 P 0.98 Mg 0.02 S 4.48 O 0.02 Cl1.5 Li 5.54 P 0.98 In 0.02 S 4.47 O 0.03 Cl 1.5 Li 5.54 P 0.98 Bi 0.02 S 4.47 O 0.03 Cl 1.5 and Li 5.5 P 0.96 S 0.04 S 4.40 O 0.10 Cl 1.5 In the XRD patterns, no diffraction peaks appeared in the 2θ ranges of 27°~27.3°, 29°~29.5°, and 35°~35.2° under different M-element doping conditions. This indicates that by introducing specific doping elements and optimizing the doping amount, the formation of impurity phases such as Li2S, LiCl, and P can be effectively suppressed, and a high-purity sulfide solid electrolyte can be obtained. As shown in Figure 6, Li after doping 5.92 P 0.86 Mg 0.14 S 4.36 O 0.14 Cl 1.5 In the XRD pattern, if the amount of M element doping is excessive, With b > 0.1, a diffraction peak for MgO appears at a position of 43.3° in the 2θ range. This indicates that introducing an excess of a specific doping element may lead to the formation of a new impurity phase.

[0059] As shown in Table 1, a comparison of Examples 1-15 and Comparative Examples 1-3 reveals that when sulfide solid electrolytes are not doped with M and O elements, they exhibit diffraction peaks of at least one impurity from Li2S, P, or LiCl, indicating low purity. When doped with M and O elements, no diffraction peaks appear in the XRD pattern in the 2θ ranges of 27°-27.3°, 29°-29.5°, and 35°-35.2°, indicating a purity of over 99% for the sulfide solid electrolyte. This demonstrates that doping suppresses impurity formation, reduces side reactions such as irreversible lithium ion consumption and decreased Coulomb efficiency, improves the Coulomb efficiency of lithium-ion batteries, and consequently improves the energy efficiency and cycle characteristics of lithium-ion batteries.

[0060] As shown in Table 1, a comparison of Examples 1-5 and Comparative Example 4 reveals that when Mg is selected as the M element in the sulfide solid electrolyte, as the amount of Mg doping increases, the purity of the sulfide solid electrolyte initially increases, then decreases, and the cycle characteristics of the lithium-ion battery gradually increase, then gradually decrease. This indicates that, at low Mg doping concentrations, the main diffraction peaks of these samples correlate well with the pure silver sulfide germanite structure (Li7PS6, see XRD standard card PDF#0868), and no significant impurity phases are observed in the pattern, indicating that the desired Mg-O co-doped electrolyte was successfully fabricated. However, as the doping concentration increases further, diffraction peaks of the MgO impurity phase appear in the XRD pattern, and the purity and electrochemical properties of the sulfide solid electrolyte decrease. Therefore, by controlling the doping concentration of the M element, it is possible to improve the purity of the sulfide solid electrolyte and the electrochemical performance of the lithium-ion battery while suppressing the formation of impurity phases.

[0061] As shown in Table 1, and as can be seen by comparing Examples 3, 6-8, when the amount of Mg element doping in the sulfide solid electrolyte is the same, increasing or decreasing the Cl element content does not significantly change the purity, but the cycle characteristics of the lithium-ion battery deteriorate. Therefore, by controlling the amount of Mg doping, it is possible to control the purity of the sulfide solid electrolyte, control the Cl content, and ensure the performance of the lithium-ion battery with the sulfide solid electrolyte.

[0062] As shown in Table 1, a comparison of Examples 3, 9-10 reveals that when the amount of Mg doping in the sulfide solid electrolyte is the same, adding one or more elements of Br or I reduces the battery's cycle characteristics, although the change in purity is not significant. Therefore, selecting Cl as X can improve the electrical properties of the lithium-ion battery. A comparison of Examples 3, 11-15 reveals that even when other elements are selected as the M doping element, controlling the amount of M doping can suppress the formation of impurity phases and improve the purity of the sulfide solid electrolyte. However, when SSb, In, Bi, or Mg is selected as M, the cycle characteristics of the lithium-ion battery are better. Therefore, by controlling the type and amount of M doping, it is possible to control the nucleation and growth of the sulfide solid electrolyte, control the thermodynamics and kinematics during the growth process, increase the formation rate of the target product, suppress the generation of impurity phases, thereby improving phase purity and ultimately improving the performance of the lithium-ion battery.

[0063] The present invention further provides electronic devices. The electronic device includes at least one of the lithium-ion batteries, which are used to supply electrical energy. Here, the electronic device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid electric vehicle, an extended-range electric vehicle, etc. A spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc. Electric toys include stationary or portable electric toys such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Electric tools include, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, electric planers, and other electric tools for cutting metal, electric tools for grinding, electric tools for assembly, and electric tools for railways. Since the electronic device includes the lithium-ion battery, the advantages of including the lithium-ion battery will not be described in detail here. [Industrial applicability]

[0064] In summary, the present invention presents a sulfide solid electrolyte, a method for producing the same, and its applications. By controlling the type of raw materials used in the synthesis of the sulfide solid electrolyte, nucleation of the sulfide solid electrolyte can be promoted, the grain growth direction and rate can be controlled, resulting in more uniform particle size, improved crystallinity, reduced impurity phases at grain boundaries, and improved phase purity. Simultaneously, by selecting the synthesis raw materials, the thermodynamic and kinetic conditions of the reaction can be changed, enabling thermodynamic and dynamical control. This lowers the Gibbs free energy for impurity phase formation, making it easier for the reaction to produce the crystalline phase of the sulfide solid electrolyte, improving the rate of production of the target product, and suppressing the formation of impurity phases. By introducing specific doping elements and optimizing the doping amount, the formation of impurity phases such as Li2S, LiCl, and P can be effectively suppressed, resulting in a high-purity sulfide solid electrolyte, and improving the air stability and chemical stability of the sulfide solid electrolyte. High-purity doped sulfide solid electrolytes can be obtained, reducing irreversible lithium-ion consumption and Coulomb efficiency degradation caused by impurities. These side reactions are reduced, Coulomb efficiency is improved, and consequently, the energy efficiency and cycle performance of the battery can be improved.

[0065] The above description represents preferred embodiments of the present application and merely describes the technical principles employed. Those skilled in the art should understand that the scope of the present invention is not limited to technical solutions formed by specific combinations of the above technical features, but also includes, without departing from the spirit of the invention, other technical solutions formed by any combination of the above technical features or their equivalents, including, for example, technical solutions formed by replacing the above features with (but not limited to) similarly functional technical features disclosed in this application.

[0066] Other technical features not described herein are well known to those skilled in the art. To emphasize the innovative features of the present invention, other technical features will not be described in detail here.

Claims

1. A sulfide solid electrolyte, The molecular formula of the sulfide solid electrolyte is Li ａ P １－ｂ M ｂ S ｃ O ｄ X ｅ The formula is such that 5 < a < 10, 0 < b < 1, 3 < c < 6, 0 < d < 2.5, 4 < c + d < 6, 0 < e < 2; M is one or more selected from Al, Ga, In, Ti, Sc, As, Sb, Bi, V, Nb, Ca, Mg, Sr, Ba, Zn, Cr, Sn, or Pb, and X is one or more selected from Cl, Br, or I, and no diffraction peaks appear in the CuKα X-ray diffraction pattern of the sulfide solid electrolyte powder in the ranges of 27° to 27.3°, 29° to 29.5° and 35° to 35.2°. A sulfide solid electrolyte characterized by the following features.

2. M is one or more selected from Sb, In, Bi, or Mg, and X is selected from Cl. The sulfide solid electrolyte according to feature 1.

3. The range of values ​​for b is 0 < b ≤ 0.

1. The sulfide solid electrolyte according to feature 1.

4. The purity of the sulfide solid electrolyte exceeds 99%. The sulfide solid electrolyte according to feature 1.

5. The process involves mixing Li, P, M, S, and X sources in stoichiometric ratios according to the chemical formula of a sulfide solid electrolyte, followed by polishing to obtain a sulfide solid electrolyte precursor powder. The sulfide solid electrolyte precursor powder is subjected to calcination treatment to obtain the sulfide solid electrolyte, A method for producing a sulfide solid electrolyte according to any one of claims 1 to 4, characterized by including the following:

6. The Li source is one or more selected from LiCl, LiBr, LiI or Li ２ S; the P source is elemental P, P ２ S ５ , P ４ S ６ , PCl ５ or PBr ５ and is one or more selected from the above; the M source is one or more selected from an oxide of M or a sulfide of M; the S source is one or more selected from elemental S, Li ２ S, P ２ S ５ , P ４ S ６ or a sulfide of M, and the sulfide of M includes one or more selected from As ２ S ５ , As ２ S ３ , Sb ２ S ５ , Sb ２ S ３ , Bi ２ S ５ , Bi ２ S ３ , Al ２ S ３ , Ga ２ S ３ , In ２ S ３ , Sc ２ S ３ , MgS, CaS, SrS, BaS, ZnS, CrS, SnS or PbS and includes one or more selected from the above; the X source is one or more selected from LiCl, PCl ５ , LiBr, PBr ５ , LiI or I ２ and is one or more selected from the above; the O element in the chemical formula is derived from the oxide of M, The method for producing a sulfide solid electrolyte according to feature 5.

7. The polishing time ranges from 1 to 48 hours, the polishing speed from 50 rpm to 1500 rpm, and the ball-to-material ratio from 1:1 to 100:

1. The method for producing a sulfide solid electrolyte according to feature 5.

8. The firing temperature is 400°C to 600°C, and the firing time is 1 hour to 24 hours. The method for producing a sulfide solid electrolyte according to feature 5.

9. at least, Positive electrode sheet and Negative electrode sheet and A solid electrolyte membrane comprising a sulfide solid electrolyte according to any one of claims 1 to 4, disposed between adjacent positive electrode sheets and negative electrode sheets, A solid-state lithium-ion battery characterized by containing [the specified component].

10. An electronic device characterized by comprising the all-solid-state lithium-ion battery described in claim 9.

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