Sulfide solid electrolyte and preparation method and application thereof

Abstract

The invention provides a sulfide solid electrolyte as well as a preparation method and application thereof. The molecular formula of the sulfide solid electrolyte is Li P < 1-b > M S < c > O < d > X < e >, wherein: 5lt; a < lt >; 6; 0 lt; blt; 1; 1.5 1t; clt; ct; 5, 0lt; dlt; 2.5, 4lt; c + dlt; 5, 1lt; lt, lt; 2; m is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb; x is selected from one or more of Cl, Br or I. According to the sulfide solid electrolyte and the preparation method and application thereof, the stability of the conductivity of the sulfide solid electrolyte can be improved, the air stability is enhanced, the electrolyte / active substance interface property is improved, the service life of an all-solid-state lithium ion battery is prolonged, and the safety of the all-solid-state lithium ion battery is improved.

Description

[0001] This application claims partial priority from a Chinese patent application with the application number 202411418926.2, titled "A Sulfide Solid Electrolyte and Its Preparation Method and Application", filed on October 11, 2024, and its relevant content is incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of lithium-ion batteries, and particularly relates to a sulfide solid electrolyte and its preparation method and application. Background Art

[0003] Due to advantages such as high energy density, high power density, and long cycle life, lithium-ion batteries have been widely used in fields such as portable electronic devices, electric vehicles, and energy storage systems. However, traditional lithium-ion batteries use flammable organic liquid electrolytes, which pose safety hazards and limit their further development. To overcome the safety problems of organic liquid electrolytes, solid-state lithium batteries have received extensive attention in recent years. Solid-state lithium batteries use solid electrolytes to replace traditional organic liquid electrolytes, and have advantages such as higher safety, a wider electrochemical window, and a longer cycle life.

[0004] Currently, sulfide solid electrolytes are widely used in lithium-ion batteries. However, most of the existing preparation methods of sulfide electrolytes are complex, costly, and the prepared sulfide solid electrolytes are prone to deliquescence and instability in air. In addition, the electrochemical performance of existing sulfide electrolytes in lithium-ion batteries, especially the cycle life, needs to be further improved. Summary of the Invention

[0005] The present invention provides a sulfide solid electrolyte and its preparation method and application. Through the sulfide solid electrolyte and its preparation method and application provided by the present invention, it is possible to improve the conductivity stability of the sulfide solid electrolyte, enhance air stability, and improve the electrolyte / active material interface properties, thereby improving the life and safety of all-solid-state lithium-ion batteries and lithium batteries.

[0006] To solve the above technical problems, the present invention provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li a P 1-b M b S c O d X e ; wherein: 5 < a < 6; 0 < b < 1; 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2; M is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V, or Nb; X is selected from one or more of Cl, Br, or I.

[0007] In one embodiment of the present invention, M is selected from one or more of Sb, In or Bi.

[0008] In one embodiment of the present invention, X is selected from Cl; and the value range of b is 0<b≤0.1.

[0009] The present invention also provides a method for preparing the above-mentioned sulfide solid electrolyte, comprising the steps of:

[0010] According to the chemical formula of the sulfide solid electrolyte, a Li source, a P source, an M source, a S source and an X source are mixed in a stoichiometric amount, and the mixture is placed in a ball mill for ball milling to obtain a sulfide solid electrolyte precursor powder; and

[0011] The sulfide solid electrolyte precursor powder is calcined at a preset temperature to obtain the sulfide solid electrolyte.

[0012] In one embodiment of the present invention, the Li source is selected from one or more of LiCl, LiBr, LiI or Li2S; the P source is selected from one or more of elemental P, P2S5, P4S6, PCl5 or PBr5; the M source is selected from one or more of oxides of M or sulfides of M; the S source is selected from one or more of elemental S, Li2S, P2S5, P4S6, As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3 or Sc2S3; the X source is selected from one or more of LiCl, PCl5, LiBr, PBr5, LiI or I2; the O element in the chemical formula comes from the oxide of M.

[0013] In one embodiment of the present invention, the ball milling time is 1 hour to 48 hours, the ball milling speed is 50 rpm to 1500 rpm, and the ball-to-material ratio is 1:1 to 100:1.

[0014] In one embodiment of the present invention, the preset temperature is 400° C. to 600° C., and the calcination treatment time is 1 hour to 18 hours.

[0015] The present invention also provides an all-solid-state lithium-ion battery, comprising at least:

[0016] A positive electrode sheet, wherein the positive electrode sheet comprises a halide solid electrolyte, wherein the halide solid electrolyte comprises Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 ;

[0017] A negative electrode; and

[0018] A solid electrolyte membrane, wherein the solid electrolyte membrane is disposed between the adjacent positive electrode sheet and the negative electrode sheet, and the solid electrolyte membrane comprises the above-mentioned sulfide solid electrolyte.

[0019] In one embodiment of the present invention, the positive electrode plate includes a positive electrode active material, and the positive electrode active material is selected from one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide or lithium nickel cobalt aluminum oxide.

[0020] The present invention also provides an electronic device, comprising the all-solid-state lithium-ion battery described above.

[0021] In summary, the present invention proposes a sulfide solid electrolyte and a preparation method and application thereof. By introducing +3 or +5 valence M elements and O elements into the sulfide solid electrolyte, LiCl, Li2O and Li-Sb / Li-Bi / Li-In alloys can be formed in the electrolyte / lithium metal negative electrode interface layer, the electric field can be homogenized, the local current density can be balanced, and the nucleation and growth of Li can be regulated, and the rapid growth of lithium dendrites at the growth interface can be effectively inhibited, and the stability and performance of lithium ion batteries can be significantly improved, and the life and safety of all-solid-state lithium ion batteries can be improved. The inherent resistance of the sulfide solid electrolyte to atmospheric degradation is improved, and the generation of H2S is effectively reduced, and the possibility of the battery in actual production is increased, thereby enhancing the air stability and chemical stability of the sulfide solid electrolyte. The sulfide solid electrolyte has higher stability and specific reactivity, and can improve the stability of the conductivity of the sulfide solid electrolyte, enhance air stability, and improve the electrolyte / active material interface properties, thereby improving the compatibility with active materials. It can improve the ionic conductivity and electrochemical stability of the sulfide solid electrolyte and improve the voltage stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 This is a 1C / 1C long cycle performance diagram of the all-solid-state lithium-ion battery in Example 3 at room temperature.

[0024] Figure 2 This is the SEM image of the sulfide solid electrolyte in Example 3. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0027] The technical solutions of the present invention will be further described in detail below in conjunction with several embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0028] The present invention provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li a P 1- b M b S c O d X e , where 5 < a < 6; 0 < b < 1; 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2, M is selected from, for example, one or more of Al, Ga, In, Ti, Sc, Sb, Bi, As, V, or Nb, and X is selected from, for example, one or more of Cl, Br, or I. Among them, introducing M element and O element into the sulfide solid electrolyte rich in halogen elements will form P-O and M-S bonds in the crystal structure, thereby improving the inherent resistance to atmospheric degradation and effectively reducing the generation of H2S, enhancing the air stability and chemical stability of the sulfide solid electrolyte. In addition, when using this sulfide solid electrolyte to assemble a all-solid-state lithium-ion battery, alloys such as LiCl, Li2O, and Li-Sb / Li-Bi / Li-In can be formed at the electrolyte / lithium metal negative electrode interface layer. Among them, Li2O has a high intrinsic ionic conductivity, and alloys such as Li-Sb / Li-Bi / Li-In can promote the rapid transfer kinetics of Li + , make the electric field uniform, balance the local current density, and thus regulate the nucleation and growth of Li. In addition, LiCl has a high interfacial energy, which can effectively inhibit the rapid growth of lithium dendrites at the growth interface, can significantly improve the stability and performance of the lithium-ion battery, and improve the life and safety of the all-solid-state lithium-ion battery and the lithium battery.

[0029] In one embodiment of the present invention, M is selected from one or more of Sb, In or Bi, for example. Since the ionic radius of Sb, In or Bi is moderate, and the ionic radius of these elements is close to the ionic radius of the main elements in the sulfide electrolyte, such as sulfur and phosphorus, they can more easily replace the position of the main elements when doped without causing excessive lattice distortion. In addition, Sb, In or Bi has moderate electronegativity, and can form a stable chemical bond with the sulfur element in the sulfide, which is difficult to be damaged by external influences, so that the sulfide solid electrolyte has high stability and specific reactivity, and can improve the stability of the conductivity of the sulfide solid electrolyte, enhance air stability and improve the electrolyte / active material interface properties, thereby improving the compatibility with the active material.

[0030] In one embodiment of the present invention, X is selected from halogen elements, and depending on the halogen, the degree of anion disorder between the 4a and 4c sites in the crystal structure of the sulfide solid electrolyte is different, ranging from a small amount of anti-site defects when X is I to 60% site disorder when X is Cl, and the lithium conductivity of these compounds mainly depends on the degree of disorder occupied by anion and cation sites. Therefore, X is selected from Cl, for example, to improve the ionic conductivity and electrochemical stability of the sulfide solid electrolyte and improve voltage stability. The value range of b is 0<b≤0.1. In a specific embodiment of the present invention, when M is +5 valence, b is optimally 0.04, and when M is +3 valence, b is optimally 0.02, so as to improve the cycle performance of the lithium ion battery.

[0031] The present invention also proposes a method for preparing a sulfide solid electrolyte, which at least comprises: according to the chemical formula of the sulfide solid electrolyte, a Li source, a P source, an M source, an S source and an X source are mixed in stoichiometric amounts, and then placed in a ball mill for ball milling to obtain a sulfide solid electrolyte precursor powder; and the sulfide solid electrolyte precursor powder is calcined at a preset temperature to obtain a sulfide solid electrolyte.

[0032] In one embodiment of the present invention, according to the chemical formula of the sulfide solid electrolyte Li a P 1-b M b S c O d X e, the Li source, P source, M source, S source and X source are uniformly mixed according to stoichiometric ratio, wherein the Li source is selected from one or more of LiCl, LiBr, LiI or Li2S, the P source is selected from one or more of elemental P, P2S5, P4S6, PCl5 or PBr5, the M source is selected from one or more of oxides of M or sulfides of M, the S source is selected from one or more of elemental S, Li2S, P2S5, P4S6, As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3 or Sc2S3, the X source is selected from one or more of LiCl, PCl5, LiBr, PBr5, LiI or I2, and the O element in the chemical formula comes from the oxide of M. After the raw materials are evenly mixed, they are placed in a ball mill and ball milled in an inert gas atmosphere, wherein the ball-to-material ratio is, for example, 1:1 to 100:1, the ball milling speed is, for example, 50 rpm to 1500 rpm, and the ball milling time is, for example, 1 h to 48 h, to obtain a sulfide solid electrolyte precursor powder.

[0033] In one embodiment of the present invention, the sulfide solid electrolyte precursor powder is calcined at a preset temperature, wherein the preset temperature is 400° C. to 600° C., and the calcination time is 1 h to 18 h, to obtain a sulfide solid electrolyte.

[0034] The present invention also proposes an all-solid-state lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet and a solid electrolyte membrane, wherein the solid electrolyte membrane is arranged between adjacent positive electrode sheets and negative electrode sheets. The positive electrode sheet comprises a positive electrode active material and a halide solid electrolyte, wherein the positive electrode active material is selected from one or more of 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 halide solid electrolyte comprises Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 , the halide solid electrolyte does not produce exothermic reaction with the de-lithium positive electrode active material, thereby improving the safety of the lithium-ion battery. The negative electrode plate is, for example, one or more of a metal lithium plate, a metal indium plate, or a lithium-indium alloy plate, and the negative electrode plate includes, for example, a negative electrode active material, and the negative electrode active material is selected from one or more of a graphite material, a silicon material, or a composite material of a graphite material and a silicon material. The solid electrolyte membrane includes the above-mentioned sulfide solid electrolyte to improve the performance of the all-solid-state lithium-ion battery.

[0035] In one embodiment of the present invention, the positive electrode plate further includes a conductive agent and a binder, wherein the conductive agent is, for example, one or a combination of at least two of conductive carbon black (Super P, SP), carbon nanotubes (Carbon Nano-tube, CNT), vapor grown carbon fiber (Vapor Grown Carbon Fiber, VGCF) or graphene. The binder is, for example, polytetrafluoroethylene (PTFE) and its derivatives. The mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, (65-78): (20-30): (1-3): (1-2). In this embodiment, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, 69:29:1:1, and the conductive agent is a combination of conductive carbon black (super-P) and vapor grown carbon fiber (VGCF), and the mass ratio of the conductive carbon black and the vapor grown carbon fiber is 1:1, and the binder is, for example, polytetrafluoroethylene. After the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed, a mixed powder is obtained, and the mixed powder is pressed by dry method to obtain the positive electrode plate. In one embodiment of the present invention, when the negative electrode plate includes the negative electrode active material, the negative electrode plate also includes a solid electrolyte, a conductive agent and a binder, etc., wherein the solid electrolyte is, for example, a halide solid electrolyte or a sulfide electrolyte, etc., and this application does not make specific restrictions. The binder is, for example, at least one of polyisoprene, polyethylene or polypropylene, and the conductive agent is, for example, at least one of carbon nanotubes, carbon fibers or acetylene black. This application does not limit the ratio of the negative electrode active material, the solid electrolyte, the conductive agent and the binder, and the selection is made according to the manufacturing requirements, and the negative electrode plate is obtained, for example, by dry pressing.

[0036] In one embodiment of the present invention, in order to test the performance of the obtained sulfide solid electrolyte, for example, the sulfide solid electrolyte is cold pressed under a preset pressure to obtain a solid electrolyte membrane, wherein the preset pressure is, for example, 300MPa to 400MPa, and the thickness of the solid electrolyte membrane is, for example, 100μm to 500μm.

[0037] In one embodiment of the present invention, the negative electrode sheet is, for example, a metal lithium sheet, and the positive electrode sheet, the solid electrolyte membrane sheet, and the negative electrode sheet are placed in sequence, pressurized, and sealed in a vacuum or inert atmosphere to obtain an all-solid-state lithium-ion battery. The assembly process of the all-solid-state lithium-ion battery is, for example, completed in a glove box with an argon atmosphere.

[0038] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0039] Example 1

[0040] Preparation of sulfide solid electrolyte: Under argon atmosphere, 2 mol of Li2S, 1.5 mol of LiCl, 0.495 mol of P2S5 and 0.005 mol of Sb2O5 were placed in a tungsten steel ball mill, and tungsten steel balls were added at a ball-to-material ratio of 40:1. The ball mill was milled at 100 rpm for 10 minutes, and then at 500 rpm for 16 hours to obtain a uniformly mixed sulfide solid electrolyte precursor powder. The sulfide solid electrolyte precursor powder was placed in a crucible, sintered at 500 ° C for 10 hours, and Li was obtained after cooling. 5. 5P 0.99 Sb 0.01 S 4.475 O 0.025 Cl 1.5 .

[0041] Preparation of electrolyte membrane: 50 mg of Li 5.5 P 0.99 Sb 0.01 S 4.475 O 0.025 Cl 1.5 The electrolyte membrane was prepared by cold pressing at 360 MPa, and the electrolyte membrane had a thickness of 400 μm and a diameter of 10 mm.

[0042] Preparation of positive electrode: 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 The PTFE preparation is mixed in a mass ratio of 69:1:29:1, and the positive electrode sheet is made by a dry method. The conductive agent is super-P and VGCF in a mass ratio of 1:1, and then the positive electrode sheet is cut into discs with a diameter of 10 mm.

[0043] Negative electrode sheet: The negative electrode sheet is made of lithium metal sheet and cut into round sheets with a diameter of 10 mm.

[0044] Assembly of all-solid-state battery: Assemble the positive electrode sheet, electrolyte membrane sheet and negative electrode sheet prepared above into an all-solid-state battery.

[0045] Assembly of symmetrical battery: Place the counter electrode Li on both sides of the electrolyte membrane and assemble it with the electrolyte membrane into a Li / Li symmetrical battery.

[0046] Example 2

[0047] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.5 mol of LiCl, 0.49 mol of P2S5 and 0.01 mol of Sb2O5 is Li 5.5 P 0.98 Sb 0.02 S 4.45 O 0.05 Cl 1.5 , other operations remain the same as those in Example 1.

[0048] Example 3

[0049] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.5 mol of LiCl, 0.48 mol of P2S5 and 0.02 mol of Sb2O5 is Li 5.5 P 0.96 Sb 0.04 S 4.40 O 0.10 Cl 1.5 , other operations remain the same as those in Example 1.

[0050] Example 4

[0051] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.5 mol of LiCl, 0.47 mol of P2S5 and 0.03 mol of Sb2O5 is Li 5.5 P 0.94 Sb 0.06 S 4.35 O 0.15 Cl 1.5 , other operations remain the same as those in Example 1.

[0052] Example 5

[0053] The sulfide solid electrolyte prepared by 2 mol of Li2S, 1.5 mol of LiCl, 0.46 mol of P2S5 and 0.04 mol of Sb2O5 is Li 5.5 P 0.92 Sb 0.08 S 4.3 O 0.20 Cl 1.5 , other operations remain the same as those in Example 1.

[0054] Example 6

[0055] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5 and 0.05 mol of Sb2O5 is Li 5.5 P 0.9 Sb 0.1S 4.25 O 0.25 Cl 1.5 , other operations remain the same as those in Example 1.

[0056] Example 7

[0057] The chemical formula of the sulfide solid electrolyte prepared by 1.6 mol Li2S, 1.9 mol LiCl, 0.48 mol P2S5 and 0.02 mol Sb2O5 is Li 5.1 P 0.96 Sb 0.04 S4O 0.10 Cl 1.9 , other operations remain the same as those in Example 1.

[0058] Example 8

[0059] The chemical formula of the sulfide solid electrolyte prepared by 2.4 mol Li2S, 1.1 mol LiCl, 0.48 mol P2S5 and 0.02 mol Sb2O5 is Li 5.9 P 0.96 Sb 0.04 S 4.8 O 0.10 Cl 1.1 , other operations remain the same as those in Example 1.

[0060] Example 9

[0061] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.4 mol of LiCl, 0.1 mol of LiBr, 0.48 mol of P2S5 and 0.02 mol of Sb2O5 is Li 5.5 P 0.96 Sb 0.04 S 4.40 O 0.10 Cl 1.4 Br 0.1 , other operations remain the same as those in Example 1.

[0062] Example 10

[0063] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.3 mol of LiCl, 0.1 mol of LiBr, 0.1 mol of LiI, 0.48 mol of P2S5 and 0.02 mol of Sb2O5 is Li 5.5 P 0.96 Sb 0.04 S 4.40 O 0.10 Cl 1.3 Br 0.1 I0.1 , other operations remain the same as those in Example 1.

[0064] Embodiment 11

[0065] The chemical formula of the sulfide solid electrolyte prepared by 2.01 mol Li2S, 1.5 mol LiCl, 0.495 mol P2S5 and 0.005 mol In2O3 is Li 5.52 P 0.99 In 0.01 S 4.485 O 0.015 Cl 1.5 , other operations remain the same as those in Example 1.

[0066] Example 12

[0067] The chemical formula of the sulfide solid electrolyte prepared by 2.015 mol Li2S, 1.5 mol LiCl, 0.4925 mol P2S5 and 0.075 mol In2O3 is Li 5.53 P 0.985 In 0.015 S 4.4775 O 0.0225 Cl 1.5 , other operations remain the same as those in Example 1.

[0068] Example 13

[0069] The chemical formula of the sulfide solid electrolyte prepared by 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 , other operations remain the same as those in Example 1.

[0070] Embodiment 14

[0071] The chemical formula of the sulfide solid electrolyte prepared by 2.04 mol Li2S, 1.5 mol LiCl, 0.48 mol P2S5 and 0.02 mol In2O3 is Li 5.58 P 0.96 In 0.04 S 4.44 O 0.06 Cl 1.5 , other operations remain the same as those in Example 1.

[0072] Embodiment 15

[0073] The chemical formula of the sulfide solid electrolyte prepared by 2.06 mol Li2S, 1.5 mol LiCl, 0.47 mol P2S5 and 0.03 mol In2O3 is Li 5.62 P 0.94 In 0.06 S 4.41 O 0.09 Cl 1.5 , other operations remain the same as those in Example 1.

[0074] Example 16

[0075] The chemical formula of the sulfide solid electrolyte prepared by 2.08 mol Li2S, 1.5 mol LiCl, 0.46 mol P2S5 and 0.04 mol In2O3 is Li 5.66 P 0.92 In 0.08 S 4.38 O 0.12 Cl 1.5 , other operations remain the same as those in Example 1.

[0076] Embodiment 17

[0077] The difference between this embodiment and embodiment 1 is that the chemical formula of the sulfide solid electrolyte prepared by 2.1 mol of Li2S, 1.5 mol of LiCl, 0.45 mol of P2S5 and 0.05 mol of In2O3 is Li 5.7 P 0.9 In 0.1 S 4.35 O 0.15 Cl 1.5 , other operations remain the same as those in Example 1.

[0078] Embodiment 18

[0079] The chemical formula of the sulfide solid electrolyte prepared by 1.62 mol Li2S, 1.9 mol LiCl, 0.49 mol P2S5 and 0.01 mol In2O3 is Li 5.14 P 0.98 In 0.02 S 4.07 O 0.03 Cl 1.9 , other operations remain the same as those in Example 1.

[0080] Embodiment 19

[0081] The chemical formula of the sulfide solid electrolyte prepared by 2.42 mol Li2S, 1.1 mol LiCl, 0.49 mol P2S5 and 0.01 mol In2O3 is Li5.94 P 0.98 In 0.02 S 4.87 O 0.03 Cl 1.1 , other operations remain the same as those in Example 1.

[0082] Embodiment 20

[0083] The chemical formula of the sulfide solid electrolyte prepared by 2.02 mol Li2S, 1.4 mol LiCl, 0.1 mol LiBr, 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 1.4 Br 0.1 , other operations remain the same as those in Example 1.

[0084] Embodiment 21

[0085] The chemical formula of the sulfide solid electrolyte prepared by 2.02 mol Li2S, 1.3 mol LiCl, 0.1 mol LiBr, 0.1 mol LiI, 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 1.3 Br 0. 1I 0.1 , other operations remain the same as those in Example 1.

[0086] Embodiment 22

[0087] The chemical formula of the sulfide solid electrolyte prepared by 2.01 mol Li2S, 1.5 mol LiCl, 0.495 mol P2S5 and 0.005 mol Bi2O3 is Li 5.52 P 0.99 Bi 0.01 S 4.485 O 0.015 Cl 1.5 , other operations remain the same as those in Example 1.

[0088] Embodiment 23

[0089] The chemical formula of the sulfide solid electrolyte prepared by 2.015 mol Li2S, 1.5 mol LiCl, 0.4925 mol P2S5 and 0.075 mol Bi2O3 is Li5.53 P 0.985 Bi 0.015 S 4.4775 O 0.0225 Cl 1.5 , other operations remain the same as those in Example 1.

[0090] Embodiment 24

[0091] The chemical formula of the sulfide solid electrolyte prepared by 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 , other operations remain the same as those in Example 1.

[0092] Embodiment 25

[0093] The chemical formula of the sulfide solid electrolyte prepared by 2.04 mol Li2S, 1.5 mol LiCl, 0.48 mol P2S5 and 0.02 mol Bi2O3 is Li 5.58 P 0.96 Bi 0.04 S 4.44 O 0.06 Cl 1.5 , other operations remain the same as those in Example 1.

[0094] Embodiment 26

[0095] The chemical formula of the sulfide solid electrolyte prepared by 2.06 mol Li2S, 1.5 mol LiCl, 0.47 mol P2S5 and 0.03 mol Bi2O3 is Li 5.62 P 0.94 Bi 0.06 S 4.41 O 0.09 Cl 1.5 , other operations remain the same as those in Example 1.

[0096] Embodiment 27

[0097] The chemical formula of the sulfide solid electrolyte prepared by 2.08 mol Li2S, 1.5 mol LiCl, 0.46 mol P2S5 and 0.04 mol Bi2O3 is Li 5.66 P 0.92 Bi 0.08 S 4.38 O 0.12 Cl 1.5, other operations remain the same as those in Example 1.

[0098] Embodiment 28

[0099] The chemical formula of the sulfide solid electrolyte prepared by 2.1 mol Li2S, 1.5 mol LiCl, 0.45 mol P2S5 and 0.05 mol Bi2O3 is Li 5.7 P 0.9 Bi 0.1 S 4.35 O 0.15 Cl 1.5 , other operations remain the same as those in Example 1.

[0100] Embodiment 29

[0101] The chemical formula of the sulfide solid electrolyte prepared by 1.62 mol Li2S, 1.9 mol LiCl, 0.49 mol P2S5 and 0.01 mol Bi2O3 is Li 5.14 P 0.98 Bi 0.02 S 4.07 O 0.03 Cl 1.9 , other operations remain the same as those in Example 1.

[0102] Embodiment 30

[0103] The chemical formula of the sulfide solid electrolyte prepared by 2.42 mol Li2S, 1.1 mol LiCl, 0.49 mol P2S5 and 0.01 mol Bi2O3 is Li 5.94 P 0.98 Bi 0.02 S 4.87 O 0.03 Cl 1.1 , other operations remain the same as those in Example 1.

[0104] Embodiment 31

[0105] The chemical formula of the sulfide solid electrolyte prepared by 2.02 mol Li2S, 1.4 mol LiCl, 0.1 mol LiBr, 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 1.4 Br 0.1 , other operations remain the same as those in Example 1.

[0106] Embodiment 32

[0107] The chemical formula of the sulfide solid electrolyte prepared by 2.02 mol Li2S, 1.3 mol LiCl, 0.1 mol LiBr, 0.1 mol LiI, 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 1.3 Br 0. 1I 0.1 , other operations remain the same as those in Example 1.

[0108] Comparative Example 1

[0109] The chemical formula of the sulfide solid electrolyte prepared by 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 , other operations remain the same as those in Example 1.

[0110] Comparative Example 2

[0111] The chemical formula of the sulfide solid electrolyte prepared by 2 mol of Li2S, 1.4 mol of LiCl, 0.1 mol of LiBr and 0.5 mol of P2S5 is Li 5.5 PS 4.5 Cl 1.4 Br 0.1 , other operations remain the same as those in Example 1.

[0112] Comparative Example 3

[0113] The electrolyte chemical formula is Li prepared by 2 mol Li2S, 1.3 mol LiCl, 0.1 mol LiBr, 0.1 mol LiI and 0.5 mol P2S5. 5.5 PS 4.5 Cl 1.3 Br 0.1 I 0.1 , other operations remain the same as those in Example 1.

[0114] In Examples 1-32 and Comparative Examples 1-3 of the present invention, different sulfide solid electrolytes are used to test the ionic conductivity of the sulfide solid electrolytes, and the sulfide solid electrolytes are exposed to a dry room at -40°C for 24 hours, and then the ionic conductivity test is performed again. In this embodiment, the ionic conductivity is obtained, for example, by an AC impedance method, and the test results are shown in Table 1.

[0115] In Examples 1-32 and Comparative Examples 1-3 of the present invention, different sulfide solid electrolytes are used to obtain lithium-ion batteries. At 25°C, the lithium-ion batteries prepared above are subjected to long-cycle charge and discharge, and their discharge capacity is measured, and the energy density is calculated. The operating voltage range of the battery test is 2.5V to 4.3V, the charge and discharge rate is 1C / 1C, and the discharge capacity of the first cycle is recorded as the 1C discharge capacity. When the battery capacity reaches 80% of the first cycle capacity (80% State of Health, 80% SOH), the test is terminated to obtain the number of cycles at room temperature. The symmetrical battery is charged at 1 mA / cm 2 The constant current charge-discharge cycle test was carried out at a current density of , and the test results are shown in Table 2.

[0116] Table 1. Ionic conductivity of sulfide solid electrolytes in Examples 1-32 and Comparative Examples 1-3

[0117]

[0118] Table 2. Test results of lithium-ion batteries and symmetrical batteries in Examples 1-32 and Comparative Examples 1-3

[0119]

[0120] Refer to Table 1 and Table 2. Comparison of Example 1-32 and Comparison 1-3 shows that when the M element and the O element are not added to the electrolyte, the lithium-ion battery has almost no cycle performance and a short circuit occurs quickly, indicating that when the M element and the O element are missing, the chemical stability of the sulfide solid electrolyte material is poor, the mechanical strength is insufficient, and it is difficult to ensure the long-term cycle performance of the lithium-ion battery. By introducing the M element and the O element, the cycle performance of the lithium-ion battery can be improved.

[0121] Please refer to Table 1 and Table 2. It can be seen from Comparative Examples 1-6 that when the M element in the sulfide solid electrolyte selects Sb, as the doping amount of Sb increases, the cycle performance of the lithium-ion battery gradually increases and then gradually decreases. In Comparative Examples 11-17, when the M element in the sulfide solid electrolyte selects In, as the doping amount of In increases, the cycle performance of the lithium-ion battery gradually increases and then gradually decreases. In Comparative Examples 22-28, when the M element in the sulfide solid electrolyte selects Bi, as the doping amount of Bi increases, the cycle performance of the lithium-ion battery first gradually increases and then gradually decreases. When the doping amount of Sb, In or Bi elements is too low, the battery short circuit occurs when the number of cycles is small. And as the doping amount of M element increases, the ionic conductivity of the sulfide solid electrolyte decreases, but the ionic conductivity retention rate after exposure to -40°C dry room for 24h increases, enhancing the air stability and chemical stability of the sulfide solid electrolyte, and improving the stability and performance of the battery. Therefore, controlling the doping amount of M in the sulfide solid electrolyte can improve the cycle life and safety of the all-solid-state lithium-ion battery, while maintaining the ionic conductivity at a high level, ensuring the rate performance of the lithium-ion battery, and improving the charge and discharge efficiency and cycle life. High ionic conductivity can reduce the internal resistance of the battery and increase the power density and energy density of the battery.

[0122] See also Figure 1 As shown, in the all-solid-state lithium-ion battery of Example 3, during the cycle at room temperature, the current density used for constant current charging and discharging is 1C, Figure 1 It can be seen that at a current density of 1C, the all-solid-state lithium-ion battery in Example 3 still has an energy storage capacity of about 160 mAh / g after 500 cycles, indicating that the sulfide solid electrolyte has excellent reaction kinetics and cycle stability, and the obtained solid electrolyte membrane has a good gain effect on the cycle stability and reaction activity specific capacity of the battery. The all-solid-state lithium-ion battery has excellent specific capacity, rate performance and cycle life.

[0123] See also Figure 2 As shown, the sulfide solid electrolyte obtained in Example 3 was characterized by scanning electron microscope (SEM) images. Figure 2 It can be seen that the sulfide electrolyte prepared by ball milling has an irregular morphology and a particle size of 2μm to 8μm. This particle size is conducive to maintaining a high ionic conductivity while achieving better battery cycle stability.

[0124] Refer to Table 1 and Table 2. By comparing Examples 3, 7 and 8, Examples 13, 18 and 19, and Examples 24, 29 and 30, it can be seen that when the doping amount of Sb, In or Bi in the sulfide solid electrolyte is the same, increasing or decreasing the Cl element content will cause a serious decrease in ionic conductivity and reduce the cycle performance of the lithium ion battery. Therefore, the Cl element content is controlled to ensure the ionic conductivity of the sulfide solid electrolyte and the performance of the lithium ion battery.

[0125] As shown in Table 1 and Table 2, by comparing Examples 3, 9 and 10, Examples 13, 20 and 21, and Examples 24, 31 and 32, it can be seen that when the doping amount of Sb, In or Bi in the sulfide solid electrolyte is the same, the addition of one or more of Br or I will reduce the cycle performance of the battery. Therefore, X selects Cl element, which can improve the ionic conductivity and electrochemical stability of the sulfide solid electrolyte and improve the voltage stability.

[0126] The present invention also provides an electronic device, the electronic device includes at least one of the above-mentioned lithium-ion batteries, and the lithium-ion battery is used to provide electrical energy. Among them, the electronic device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and 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 can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The electronic device includes the above-mentioned lithium-ion battery, so the advantages of the above-mentioned lithium-ion battery are included, which will not be elaborated here.

[0127] In summary, the present invention proposes a sulfide solid electrolyte and a preparation method and application thereof. By introducing +3 or +5 valence M elements and O elements into the sulfide solid electrolyte, LiCl, Li2O and Li-Sb / Li-Bi / Li-In alloys can be formed in the electrolyte / lithium metal negative electrode interface layer, the electric field can be homogenized, the local current density can be balanced, and the nucleation and growth of Li can be regulated, and the rapid growth of lithium dendrites at the growth interface can be effectively inhibited, and the stability and performance of lithium ion batteries can be significantly improved, and the life and safety of all-solid-state lithium ion batteries can be improved. The inherent resistance of the sulfide solid electrolyte to atmospheric degradation is improved, and the generation of H2S is effectively reduced, and the possibility of the battery in actual production is increased, thereby enhancing the air stability and chemical stability of the sulfide solid electrolyte. The sulfide solid electrolyte has higher stability and specific reactivity, and can improve the stability of the conductivity of the sulfide solid electrolyte, enhance air stability, and improve the electrolyte / active material interface properties, thereby improving compatibility with active materials. It can improve the ionic conductivity and electrochemical stability of the sulfide solid electrolyte and improve the voltage stability.

[0128] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0129] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A sulfide solid electrolyte, characterized in that: The molecular formula of the sulfide solid electrolyte is Li a P 1- b M b S c O d X e ; wherein: 5 < a < 6; 0 < b < 1; 1.5 < c < 5, 0 < d < 2.5, 4 < c + d < 5, 1 < e < 2; M is selected from one or more of Al, Ga, In, Ti, Sc, As, Sb, Bi, V or Nb; X is selected from one or more of Cl, Br or I.

2. The sulfide solid electrolyte according to claim 1, characterized in that M is selected from one or more of Sb, In and Bi.

3. The sulfide solid electrolyte according to claim 1, characterized in that X is selected from Cl; the value range of b is 0<b≤0.

1.

4. A method for preparing a sulfide solid electrolyte according to any one of claims 1 to 3, characterized in that: Includes steps: According to the chemical formula of the sulfide solid electrolyte, a Li source, a P source, an M source, a S source and an X source are mixed in a stoichiometric amount, and the mixture is placed in a ball mill for ball milling to obtain a sulfide solid electrolyte precursor powder; and The sulfide solid electrolyte precursor powder is calcined at a preset temperature to obtain the sulfide solid electrolyte.

5. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The Li source is selected from one or more of LiCl, LiBr, LiI or Li2S; the P source is selected from one or more of elemental P, P2S5, P4S6, PCl5 or PBr5; the M source is selected from one or more of oxides of M or sulfides of M; the S source is selected from one or more of elemental S, Li2S, P2S5, P4S6, As2S5, As2S3, Sb2S5, Sb2S3, Bi2S5, Bi2S3, Al2S3, Ga2S3, In2S3 or Sc2S3; the X source is selected from one or more of LiCl, PCl5, LiBr, PBr5, LiI or I2; the O element in the chemical formula comes from the oxide of M.

6. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The ball milling time is 1h to 48h, the ball milling speed is 50rpm to 1500rpm, and the ball-to-material ratio is 1:1 to 100:

1.

7. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The preset temperature is 400° C. to 600° C., and the calcination treatment time is 1 hour to 18 hours.

8. An all-solid-state lithium-ion battery, characterized in that: At least: A positive electrode sheet, wherein the positive electrode sheet comprises a halide solid electrolyte, wherein the halide solid electrolyte comprises Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 ; A negative electrode; and A solid electrolyte membrane, wherein the solid electrolyte membrane is disposed between the adjacent positive electrode sheet and the negative electrode sheet, and the solid electrolyte membrane comprises the sulfide solid electrolyte according to any one of claims 1 to 3.

9. The all-solid-state lithium-ion battery according to claim 8, characterized in that: The positive electrode plate includes a positive electrode active material, and the positive electrode active material is selected from one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide or lithium nickel cobalt aluminum oxide.

10. An electronic device, characterized in that: An all-solid-state lithium-ion battery comprising any one of claims 8 to 9.

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