Solid electrolyte material, preparation method therefor and lithium ion battery

Abstract

The present disclosure provides a solid electrolyte material, a preparation method therefor and a lithium ion battery. The preparation method for a solid electrolyte material comprises: in an inert gas environment both the water content and the oxygen content of which are not higher than 0.01 ppm, performing ball milling on lithium nitride and tantalum halide in a mole ratio of 0.4-3:1, the ball milling rotating speed being not lower than 500 rmp, and the ball milling time being 30-300 h.

Description

Solid electrolyte material, preparation method thereof and lithium ion battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 202410252443.3, filed with the State Intellectual Property Office of China on March 6, 2024, entitled “A solid electrolyte material, its preparation method and lithium-ion battery”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the technical field of lithium-ion batteries, and in particular to a solid electrolyte material, a preparation method thereof, and a lithium-ion battery. Background Art

[0004] Currently, inorganic solid electrolytes suitable for lithium-ion batteries include sulfide, halide, and oxide types. Oxide-type solid electrolytes include garnet, perovskite, and LISICON types. Garnet-type solid electrolytes have excellent electrical conductivity, a wide electrochemical window, and excellent mechanical and thermal properties, and are considered to be more ideal Li+ ion conductors. Sulfide-type solid electrolytes have excellent mechanical ductility and high ionic conductivity comparable to that of liquid electrolytes (up to 25mS cm-1), and are one of the electrolyte materials that are expected to achieve high-energy density all-solid-state batteries. Representative sulfide-type solid electrolytes include Li6PS5Cl, Li3PS4, Li7P3S11, Li10GeP2S12, etc. Halide-type solid electrolytes have low ionic conductivity.

[0005] However, oxide-based solid electrolytes are brittle and have unfavorable mechanical properties (e.g., high Young's modulus, low fracture toughness). Furthermore, oxide-based solid electrolytes have limited compatibility with current cathode chemistries. Sulfide-based electrolytes suffer from poor air stability, a narrow electrochemical window, and chemical / electrochemical incompatibility with high-voltage cathodes and lithium metal anodes.

[0006] Therefore, it is necessary to provide a halide-type solid electrolyte with higher ionic conductivity.

[0007] Summary of the Invention

[0008] A method for preparing a solid electrolyte material comprises: ball milling lithium nitride and tantalum halide in a molar ratio of 0.4-3:1 in an inert gas environment with a water content and an oxygen content both not higher than 0.01 ppm, at a ball milling speed not lower than 500 rpm and for a ball milling time of 30-300 hours.

[0009] A solid electrolyte material prepared according to the preparation method provided in the first aspect, wherein the chemical formula of the solid electrolyte material is Li3xTaA5Nx, 0.4≤x≤3, and A is selected from F, Cl, Br or I.

[0010] A lithium-ion battery comprising a negative electrode, a solid electrolyte and a positive electrode arranged in sequence, wherein the material forming the solid electrolyte comprises the solid electrolyte material provided in the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0012] FIG1 is a schematic diagram of the structure of a lithium-ion battery provided by an example of the present disclosure;

[0013] FIG2 is an XRD test diagram of the solid electrolyte material provided in Example 2 of the present disclosure;

[0014] FIG3 is a discharge capacity test curve diagram of a lithium-ion battery provided in Example 8 of the present disclosure at different temperatures;

[0015] FIG4 is a graph showing the cycle performance test of a lithium-ion battery provided in Example 8 of the present disclosure at -40°C;

[0016] FIG5 is a graph showing the cycle performance test of a lithium-ion battery provided in Example 8 of the present disclosure at -60°C;

[0017] FIG6 is a graph showing the cycling performance test of a lithium-ion battery provided in Example 9 of the present disclosure at -10°C;

[0018] FIG7 is a graph showing the cycle performance test of a lithium-ion battery provided in Example 10 of the present disclosure at -30°C;

[0019] FIG8 is a charge and discharge test curve of the lithium-ion battery provided in Example 11 of the present disclosure at 25° C. and 0.1C;

[0020] FIG9 is a charge and discharge test curve of the lithium-ion battery provided in Example 11 of the present disclosure at 25° C. and 2C;

[0021] FIG10 is a graph showing the first cycle charge and discharge test of the lithium-ion battery provided in Example 11 of the present disclosure at -10°C.

[0022] Icon: 100 - lithium-ion battery; 101 - positive electrode; 102 - solid electrolyte; 1021 - first electrolyte layer; 1022 - second electrolyte layer; 103 - negative electrode. DETAILED DESCRIPTION

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Among them, the terms "optional" and "optional" all mean that they may be included or not (or may be present or not).

[0024] The present disclosure provides a solid electrolyte material, a preparation method thereof, and a lithium ion battery, to partially or completely improve the problem of low ion conductivity of halide-type solid electrolytes in the related art.

[0025] In the first aspect, the example of the present disclosure provides a method for preparing a solid electrolyte material, comprising: ball milling lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 in an inert gas environment in which the water content and oxygen content are both not higher than 0.01 ppm, the ball milling speed is not less than 500 rpm, and the ball milling time is 30-300 hours.

[0026] In the above implementation process, lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 are ball-milled at a speed of not less than 500 rpm for 30-300 hours in an inert gas environment with a water content and an oxygen content of not more than 0.01 ppm, to obtain a new solid electrolyte material with the chemical formula Li3xTaA5Nx, where 0.4≤x≤3, and A is selected from F, Cl, Br, or I. The new solid electrolyte material has high ionic conductivity.

[0027] In one or more embodiments, in an optional embodiment of the present disclosure, the molar ratio of lithium nitride:tantalum halide is 0.43-0.67:1.

[0028] In the above implementation process, ball milling lithium nitride and tantalum halide with a molar ratio of 0.43-0.67:1 for 30-300 hours at a ball milling speed of not less than 500 rpm can further improve the ionic conductivity of the new solid electrolyte material.

[0029] In one or more embodiments, in an optional embodiment of the present disclosure, the ball milling time is 60-140 hours.

[0030] In the above implementation process, lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 are ball-milled for 60-140 hours at a ball-milling speed of not less than 500 rpm, which can reduce the ball-milling energy consumption and improve the preparation efficiency while also improving the ionic conductivity of the solid electrolyte material.

[0031] In one or more embodiments, the tantalum halide may be selected from at least one of tantalum fluoride, tantalum chloride, tantalum bromide, or tantalum iodide.

[0032] In one or more embodiments, the lithium nitride and the tantalum halide are ball milled using a planetary ball mill.

[0033] In one or more embodiments, before the ball milling, lithium nitride and tantalum halide are put into a mortar and coarsely mixed for 10 minutes.

[0034] In a second aspect, an example of the present disclosure provides a solid electrolyte material prepared according to the preparation method provided in the first aspect, the chemical formula of the solid electrolyte material is Li3xTaA5Nx, 0.4≤x≤3, and A is selected from F, Cl, Br or I.

[0035] In the above implementation process, the solid electrolyte material Li3xTaA5Nx prepared according to the preparation method provided in the first aspect has high ionic conductivity.

[0036] In one or more embodiments, in an optional embodiment of the present disclosure, the ionic conductivity of the solid electrolyte material is not less than 1.4 mS cm-1.

[0037] In the above implementation process, the solid electrolyte material provided by the example of the present disclosure has a good ionic conductivity of not less than 1.4 mS cm-1, which can improve the electrochemical performance of the lithium-ion battery.

[0038] In a third aspect, the present disclosure provides an example of a lithium-ion battery, comprising a negative electrode, a solid electrolyte, and a positive electrode arranged in sequence, wherein the material forming the solid electrolyte comprises the solid electrolyte material provided in the second aspect.

[0039] In the above implementation process, the solid electrolyte material provided by the second aspect is added to the solid electrolyte of the lithium-ion battery. The solid electrolyte material has good ionic conductivity and can improve the electrochemical performance of the lithium-ion battery.

[0040] In one or more embodiments, in an optional embodiment of the present disclosure, the material forming the solid electrolyte further includes a second solid electrolyte material.

[0041] In one or more embodiments, the solid electrolyte includes a first electrolyte layer and a second electrolyte layer arranged in a stacked manner, wherein the solid electrolyte material forms the first electrolyte layer, and the second solid electrolyte material forms the second electrolyte layer, and the second electrolyte layer is close to the negative electrode.

[0042] In one or more embodiments, in an optional embodiment of the present disclosure, the second solid electrolyte material is selected from at least one of a sulfide electrolyte material or a halide electrolyte material.

[0043] In one or more embodiments, the second solid electrolyte material is selected from at least one of Li6PS5Cl or Li10GeP2S12.

[0044] In one or more embodiments, the mass ratio of the solid electrolyte material to the second solid electrolyte material is 2:1.

[0045] In the above-mentioned implementation process, the solid electrolyte material provided in the second aspect of the present disclosure is matched with the second solid electrolyte material. While improving the ionic conductivity of the solid electrolyte, the second electrolyte layer can also be used to separate the first solid electrolyte layer and the negative electrode to improve the interface stability between the solid electrolyte and the negative electrode, thereby further improving the electrochemical performance of the lithium-ion battery.

[0046] In one or more embodiments, in an optional embodiment of the present disclosure, the positive electrode active material of the positive electrode is selected from at least one of LiCoO2, Li3TiCl6 or Li4Ti5O12.

[0047] In one or more embodiments, the positive electrode active material of the positive electrode is selected from LiCoO2 or Li3TiCl6.

[0048] In one or more embodiments, the material forming the positive electrode further includes the solid electrolyte material provided in the second aspect.

[0049] In the above implementation process, in the lithium-ion battery, the positive electrode containing LiCoO2, Li3TiCl6 or Li4Ti5O12 positive electrode active material is used in combination with the solid electrolyte containing the solid electrolyte material provided by the second aspect of the present disclosure, which can improve the low-temperature electrochemical performance of the lithium-ion battery and enable the lithium-ion battery to still have good discharge capacity and cycle performance at low temperatures.

[0050] In one or more embodiments, in an optional embodiment of the present disclosure, the material forming the negative electrode includes at least one of Sn, In, Li, Sb, Cu, Si, Ag-C, Li-In alloy, Fe3O4, TiO2, MnO, graphite, graphene, and Li4Ti5O12.

[0051] In one or more embodiments, the material forming the negative electrode further includes a second solid electrolyte material.

[0052] In one or more embodiments, the material forming the positive electrode further includes a conductive agent; and the material forming the negative electrode further includes a conductive agent.

[0053] In the above implementation process, in the lithium-ion battery provided by the embodiment of the present disclosure, the negative electrode comprising the above material is combined with the solid electrolyte and the positive electrode provided by the example of the present disclosure to improve the electrical performance of the lithium-ion battery.

[0054] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0055] The application of lithium-ion batteries at low temperatures is an urgent problem that needs to be solved. However, the ionic conductivity of traditional electrolytes at low temperatures (≤0°C) is low, resulting in poor electrochemical performance of lithium-ion batteries. To improve these problems, researchers have modified the positive and negative electrode materials of lithium-ion batteries, as well as adjusted the electrolyte composition and solvent structure to adapt them to the harsh low-temperature environment.

[0056] Currently, research on low-temperature lithium-ion batteries focuses on adding auxiliary additives to liquid electrolytes to give the electrolyte higher ionic conductivity and lower viscosity while maintaining the required low-temperature window, but this may cause defects such as loss of high voltage stability.

[0057] The inventors believe that replacing the electrolyte with a solid-state electrolyte with low activation energy could potentially lead to the construction of low-temperature lithium-ion batteries. Activation energy represents the degree to which ionic conductivity changes with temperature. It is generally believed that the lower the activation energy, the less pronounced the change in conductivity with temperature.

[0058] However, most of the current electrolytes have low intrinsic ionic conductivity, high activation energy and large interfacial impedance between electrodes, resulting in poor low-temperature performance of lithium-ion batteries.

[0059] The inventors discovered that a solid electrolyte with a conductivity of 1 mS cm-1 can be obtained using lithium chloride and tantalum chloride as raw materials. However, the preparation time of this solid electrolyte is long, and the ionic conductivity needs to be improved.

[0060] Therefore, the present disclosure provides a solid electrolyte material, a preparation method thereof, and a lithium-ion battery to improve the problems of low ionic conductivity of solid electrolytes and poor low-temperature electrochemical performance of lithium-ion batteries.

[0061] Referring to FIG. 1 , the present disclosure provides an example of a lithium-ion battery 100 , which includes a positive electrode 101 , a solid electrolyte 102 , and a negative electrode 103 , which are sequentially arranged.

[0062] The material forming the solid electrolyte 102 includes a solid electrolyte material having a chemical formula of Li3xTaA5Nx, where 0.4≤x≤3, and A is selected from F, Cl, Br, or I.

[0063] Illustratively, x can be one of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0, or a range between any two of them.

[0064] Exemplarily, x is selected from 0.4, A is selected from Cl, and the chemical formula of the solid electrolyte material is Li1.2TaCl5N0.4.

[0065] Exemplarily, x is selected from 0.43, A is selected from Cl, and the chemical formula of the solid electrolyte material is Li1.29TaCl5N0.43.

[0066] Exemplarily, x is selected from 0.47, A is selected from Cl, and the chemical formula of the solid electrolyte material is Li1.41TaCl5N0.47.

[0067] Exemplarily, x is selected from 0.67, A is selected from Cl, and the chemical formula of the solid electrolyte material is Li2.01TaCl5N0.67.

[0068] Exemplarily, x is selected from 0.43, A is selected from Br, and the chemical formula of the solid electrolyte material is Li1.29TaBr5N0.43.

[0069] Exemplarily, x is selected from 0.43, A is selected from F, and the chemical formula of the solid electrolyte material is Li1.29TaF5N0.43.

[0070] Exemplarily, x is selected from 0.43, A is selected from I, and the chemical formula of the solid electrolyte material is Li1.29TaI5N0.43.

[0071] The solid electrolyte material is prepared by the following preparation method.

[0072] In an inert gas environment with a water content and an oxygen content not higher than 0.01 ppm, lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 are ball-milled at a ball-milling speed of not less than 500 rpm for 30-300 hours.

[0073] This disclosure demonstrates that the introduction of lithium nitride (LiN) instead of lithium chloride or other forms of nitrogen significantly reduces the ball-milling time required for tantalum halide-based electrolyte materials. Ball-milling of lithium nitride and tantalum halide yields a novel material with the chemical formula Li3xTaA5Nx. This material exhibits a high degree of amorphization and good ionic conductivity.

[0074] The present disclosure is not limited to a specific molar ratio of lithium nitride:tantalum halide. For example, the molar ratio of lithium nitride:tantalum halide can be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.5:1, 2:1, 2.5:1 or 3:1, or a range between any two of them.

[0075] Furthermore, the molar ratio of lithium nitride to tantalum halide may be 0.43-0.67:1.

[0076] Furthermore, the tantalum halide may be selected from at least one of tantalum fluoride, tantalum chloride, tantalum bromide or tantalum iodide.

[0077] Exemplarily, lithium nitride and tantalum chloride having a molar ratio of 0.4-3:1 are ball-milled at a ball-milling speed of not less than 500 rpm for 30-300 hours.

[0078] Furthermore, the present disclosure is not limited to a specific ball milling speed. For example, the ball milling speed can be selected from one of 500 rpm, 510 rpm, 520 rpm, 530 rpm, 540 rpm, 550 rpm, 560 rpm, 570 rpm, 580 rpm, 590 rpm, 600 rpm, 650 rpm or 700 rpm, or a range between any two of them.

[0079] Furthermore, the present disclosure is not limited to a specific ball milling time. For example, the ball milling time can be selected from one of 30 h, 40 h, 50 h, 60 h, 70 h, 80 h, 90 h, 100 h, 110 h, 120 h, 130 h, 140 h, 150 h, 200 h, 250 h or 300 h, or a range between any two of them.

[0080] Furthermore, the ball milling time can be 60-140 hours.

[0081] Furthermore, the lithium nitride and the tantalum halide can be ball-milled using a planetary ball mill.

[0082] Furthermore, before ball-milling the lithium nitride and the tantalum halide using a planetary ball mill, the lithium nitride and the tantalum halide may be coarsely mixed in a mortar for 10 minutes.

[0083] The solid electrolyte material provided in the examples of the present disclosure has a good ionic conductivity of not less than 1.4 mS cm-1 and a low activation energy, and can improve the low-temperature electrical performance of the lithium-ion battery 100.

[0084] Furthermore, the solid electrolyte 102 provided in the present disclosure includes a first electrolyte layer 1021 and a second electrolyte layer 1022, wherein the novel solid electrolyte material having the chemical formula Li3xTaA5Nx provided in the examples of the present disclosure forms the first electrolyte layer 1021. The second electrolyte layer 1022 is formed of a second solid electrolyte material and is located between the negative electrode 103 and the first electrolyte layer 1021.

[0085] Providing the second electrolyte layer 1022 between the negative electrode 103 and the first electrolyte layer 1021 can improve the interface stability between the negative electrode 103 and the solid electrolyte 102 .

[0086] In a possible embodiment, the second solid electrolyte material may be selected from at least one of a sulfide electrolyte material or a halide electrolyte material.

[0087] Exemplarily, the second solid electrolyte material may be selected from at least one of Li6PS5Cl or Li10GeP2S12.

[0088] Exemplarily, the material forming the solid electrolyte 102 includes a solid electrolyte material and a second solid electrolyte material, and the mass ratio of the solid electrolyte material to the second solid electrolyte material may be 2:1.

[0089] Furthermore, the present disclosure does not limit the specific material of the positive electrode 101. In one possible embodiment, the positive electrode active material of the positive electrode 101 is selected from at least one of LiCoO2, Li3TiCl6 or Li4Ti5O12.

[0090] Furthermore, the positive electrode active material may be selected from LiCoO2 or Li3TiCl6.

[0091] Compared with other positive electrode active materials such as NCM811, using at least one of LiCoO2, Li3TiCl6 or Li4Ti5O12 as the positive electrode active material in combination with the solid electrolyte 102 provided in the example of the present disclosure, which contains a new solid electrolyte material with the chemical formula Li3xTaA5Nx, can further improve the electrochemical performance of the lithium-ion battery 100 at low temperatures.

[0092] Furthermore, the material forming the positive electrode 101 may also include a solid electrolyte material having a chemical formula of Li3xTaA5Nx provided in the examples of the present disclosure.

[0093] Furthermore, the material forming the positive electrode 101 may further include a conductive agent.

[0094] In one possible embodiment, the conductive agent may be selected from conductive carbon.

[0095] Exemplarily, the material forming the positive electrode 101 includes LiCoO 2 , Li 3 x Ta A 5 N x and conductive carbon, and the mass ratio of LiCoO 2 : Li 3 x Ta A 5 N x : conductive carbon may be 7:2.5:0.5.

[0096] Exemplarily, the material forming the positive electrode 101 includes Li3TiCl6, Li3xTaA5Nx and conductive carbon, and the mass ratio of LiCoO2:Li3xTaA5Nx:conductive carbon may be 7:2.5:0.5.

[0097] Furthermore, the present disclosure does not limit the specific material of the negative electrode 103. In one possible embodiment, the material forming the negative electrode 103 may include at least one of Sn, In, Li, Sb, Cu, Si, Ag-C, Li-In alloy, Fe3O4, TiO2, MnO, graphite, graphene, and Li4Ti5O12.

[0098] Furthermore, the material forming the negative electrode 103 may further include a conductive agent.

[0099] Exemplarily, the negative electrode 103 includes a lithium sheet and an indium sheet, and the indium sheet is located on a side of the second electrolyte layer 1022 close to the solid electrolyte 102 .

[0100] For example, the material forming the negative electrode 103 may include Li6PS5Cl, conductive carbon, and nano-silicon, and the mass ratio of nano-silicon:Li6PS5Cl:conductive carbon may be 7:2.5:0.5.

[0101] Compared to In or Li-In alloys, adding nano-silicon as the negative electrode active material to negative electrode 103 can provide a higher output voltage and achieve a higher energy density for lithium-ion battery 100. Furthermore, nano-silicon is less expensive than In or Li-In alloys, which can reduce the cost of lithium-ion battery 100.

[0102] For example, the material forming the negative electrode 103 may include Li10GeP2S12, conductive carbon, and nano-silicon, and the mass ratio of nano-silicon:Li10GeP2S12:conductive carbon may be 6:3:1.

[0103] Furthermore, the lithium-ion battery 100 provided in the example of the present disclosure can also be provided with a positive electrode current collector and a negative electrode current collector, the positive electrode current collector is provided on the side of the positive electrode 101 away from the solid electrolyte 102, and the negative electrode current collector is provided on the side of the negative electrode 103 away from the solid electrolyte 102.

[0104] Furthermore, the present disclosure also provides a method for preparing a lithium-ion battery 100, comprising:

[0105] Preparation of the solid electrolyte 102: The material forming the solid electrolyte 102 is pressed into a tablet.

[0106] For example, 80 mg of Li3xTaA5Nx powder is pressed into a 10 mm mold with a pressure of 1 ton to form a first electrolyte layer 1021. Then, 40 mg of the second solid electrolyte material Li10GeP2S12 is added to one side of the first electrolyte layer 1021 and a pressure of 2 tons is applied. The pressure is maintained for 5 minutes to form a second electrolyte layer 1022 on one side of the first electrolyte layer 1021.

[0107] Preparation of the positive electrode 101: The materials forming the positive electrode 101 are mixed uniformly, and the uniformly mixed positive electrode material mixture is placed on one side of the solid electrolyte 102 and pressed into a sheet.

[0108] Illustratively, when the solid electrolyte 102 has a first electrolyte layer 1021 and a second electrolyte layer 1022 that are stacked, the uniformly mixed positive electrode material mixture is placed on a side of the first electrolyte layer 1021 facing away from the second electrolyte layer 1022 .

[0109] For example, 5 mg of the positive electrode material mixture is cold-pressed at a pressure of 3 tons onto the side of the first electrolyte layer 1021 facing away from the second electrolyte layer 1022 .

[0110] Preparation of the negative electrode 103 : The material forming the negative electrode is pressed onto the side of the solid electrolyte 102 facing away from the positive electrode 101 .

[0111] When the solid electrolyte 102 has a first electrolyte layer 1021 and a second electrolyte layer 1022 that are stacked, the negative electrode material is placed on a side of the second electrolyte layer 1022 that is away from the first electrolyte layer 1021 .

[0112] Exemplarily, when the material forming the negative electrode 103 includes a lithium sheet and an indium sheet, the indium sheet is placed on the side of the second electrolyte layer 1022 away from the first electrolyte layer 1021 , and then the lithium sheet is attached to the side of the indium sheet away from the second electrolyte layer 1022 .

[0113] For example, when the material forming the negative electrode 103 includes Li6PS5Cl, conductive carbon, and nano-silicon, the Li6PS5Cl, conductive carbon, and nano-silicon are uniformly mixed to form a negative electrode material mixture. The negative electrode material mixture is pressed against the side of the second electrolyte layer 1022 facing away from the first electrolyte layer 1021 at a pressure of 3.5 tons.

[0114] Furthermore, a current collector is inserted into the side of the positive electrode 101 and the negative electrode 103 facing away from the solid electrolyte 102 and sealed to obtain the lithium-ion battery 100 .

[0115] The solid electrolyte material, lithium-ion battery and preparation method disclosed herein are further described in detail below with reference to the embodiments.

[0116] Example 1

[0117] Example 1 provides a solid electrolyte material, and the preparation method is as follows:

[0118] Li₃N and TaCl₅ were used as raw materials, with a molar ratio of Li₃N:TaCl₅ of 0.4. These raw materials were coarsely mixed in a mortar for 10 minutes in an argon atmosphere with both H₂O and O₂ content not exceeding 0.01 ppm to form a coarse mixture. This coarse mixture was then milled in a planetary ball mill at 500 rpm for 30 hours to obtain a powdered solid electrolyte material, designated Li₁₂TaCl₅N₅₄.

[0119] Example 2

[0120] Example 2 provides a solid electrolyte material, which differs from Example 1 in that the molar ratio of Li3N:TaCl5 is 0.43. The solid electrolyte material is recorded as Li1.29TaCl5N0.43.

[0121] The XRD test curve of the solid electrolyte material Li1.29TaCl5N0.43 provided in Example 2 is shown in Figure 2. As can be seen from Figure 2, the solid electrolyte material Li1.29TaCl5N0.43 provided in the example of the present disclosure has a high degree of amorphization.

[0122] Example 3

[0123] Example 3 provides a solid electrolyte material, which differs from Example 1 in that the molar ratio of Li3N:TaCl5 is 0.47. The solid electrolyte material is recorded as Li1.41TaCl5N0.47.

[0124] Example 4

[0125] Example 4 provides a solid electrolyte material, which differs from Example 1 in that the molar ratio of Li3N:TaCl5 is 0.67. The solid electrolyte material is recorded as Li2.01TaCl5N0.67.

[0126] Example 5

[0127] Example 5 provides a solid electrolyte material, which differs from Example 2 in that the ball milling time is 60 hours. The solid electrolyte material is denoted as Li1.29TaCl5N0.43-1.

[0128] Example 6

[0129] Example 6 provides a solid electrolyte material, which differs from Example 2 in that the ball milling time is 100 hours. The solid electrolyte material is recorded as Li1.29TaCl5N0.43-2.

[0130] Example 7

[0131] Example 7 provides a solid electrolyte material, which differs from Example 2 in that the ball milling time is 140 hours. The solid electrolyte material is recorded as Li1.29TaCl5N0.43-3.

[0132] Example 8

[0133] Example 8 provides a lithium-ion battery 100, which is prepared by the following method:

[0134] (1) Preparation of solid electrolyte 102: 80 mg of the powder of the solid electrolyte material provided in Example 2 was pressed into a 10 mm battery mold with a pressure of 1 ton to form a first electrolyte layer 1021. Then, 40 mg of the second solid electrolyte material Li10GeP2S12 was added to one side of the first electrolyte layer 1021 and a pressure of 2 ton was applied. The pressure was maintained for 5 minutes to form a second solid electrolyte layer 1022, thereby obtaining a solid electrolyte 102.

[0135] (2) Preparation of positive electrode 101: 5 mg of a positive electrode material mixture was cold-pressed at a pressure of 3 tons onto the side of the first electrolyte layer 1021 facing away from the second electrolyte layer 1022 to form the positive electrode 101. The positive electrode material mixture included LiCoO2, the solid electrolyte material provided in Example 2, and conductive carbon, with a mass ratio of LiCoO2: the solid electrolyte material provided in Example 2: the conductive carbon being 7:2.5:0.5.

[0136] (3) Preparation of the negative electrode 103: A 10 mm indium sheet and a 10 mm lithium sheet were sequentially attached to the side of the second electrolyte layer 1022 facing away from the first electrolyte layer 1021 .

[0137] Then, a current collector is inserted and sealed to obtain the lithium-ion battery 100 .

[0138] Example 9

[0139] Example 9 provides a lithium-ion battery 100 , which differs from Example 8 in that the second solid electrolyte material forming the second electrolyte layer 1022 is Li 6 PS 5 Cl.

[0140] Example 10

[0141] Example 10 provides a lithium-ion battery 100, which differs from Example 8 in that the positive electrode material mixture includes Li3TiCl6, the solid electrolyte material provided by Example 2 and conductive carbon, and the mass ratio of Li3TiCl6: the solid electrolyte material provided by Example 2: the conductive carbon is 7:2.5:0.5.

[0142] Example 11

[0143] Example 11 provides a lithium-ion battery 100, which differs from Example 8 in that the positive electrode material mixture includes NCM811, the solid electrolyte material provided by Example 2 and conductive carbon, and the mass ratio of NCM811: the solid electrolyte material provided by Example 2: the conductive carbon is 7:2.5:0.5.

[0144] Comparative Example 1

[0145] Comparative Example 1 provides a solid electrolyte material, which differs from Example 1 in that the molar ratio of Li3N:TaCl5 is 0.33. The solid electrolyte material is denoted as D1.

[0146] Comparative Example 2

[0147] Comparative Example 2 provides a solid electrolyte material, which differs from Example 1 in that the molar ratio of Li3N:TaCl5 is 0.37. The solid electrolyte material is denoted as D2.

[0148] Comparative Example 3

[0149] Comparative Example 3 provides a solid electrolyte material, which differs from Example 2 in that the ball milling time is 3 hours. The solid electrolyte material is denoted as D3.

[0150] Comparative Example 4

[0151] Comparative Example 4 provides a solid electrolyte material, which differs from Example 2 in that the ball milling time is 10 hours. The solid electrolyte material is denoted as D4.

[0152] Comparative Example 5

[0153] Comparative Example 5 provides a solid electrolyte material, which differs from Example 2 in that:

[0154] Li3N and ZrCl4 were used as raw materials, and the molar ratio of Li3N:ZrCl4 was 0.43. Comparative Example 5 provided a solid electrolyte material, which was designated as D5.

[0155] Comparative Example 6

[0156] Comparative Example 6 provides a solid electrolyte material, which differs from Example 2 in that:

[0157] Li3N and NbCl5 were used as raw materials, and the molar ratio of Li3N:NbCl5 was 0.43. Comparative Example 6 provided a solid electrolyte material, which was designated as D6.

[0158] Comparative Example 7

[0159] Comparative Example 7 provides a solid electrolyte material, which differs from Example 2 in that:

[0160] Li3N and TiCl3 were used as raw materials, with a molar ratio of Li3N:TiCl3 of 0.43. Comparative Example 7 provided a solid electrolyte material, designated as D7.

[0161] Test Example 1

[0162] The solid electrolyte materials provided in Examples 1-7 and Comparative Examples 1-7 were tested for ionic conductivity, and the test results are shown in Table 1.

[0163] Table 1

[0164] Result analysis:

[0165] As can be seen from Table 1, in the example of the present disclosure, lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 are ball-milled in an inert gas environment with a water content and an oxygen content of not more than 0.01 ppm, with a ball milling speed of not less than 500 rpm and a ball milling time of 30-300 h, to obtain a solid electrolyte material with an ionic conductivity of not less than 1.49 mS cm-1.

[0166] It can be seen from Examples 1-4 and Comparative Examples 1-2 that the molar ratio of lithium nitride to tantalum halide is not less than 0.4, which can improve the ionic conductivity of the solid electrolyte material.

[0167] In combination with Examples 2, 5-7 and Comparative Examples 3-4, it can be seen that ball milling lithium nitride and tantalum halide in a specific molar ratio at no less than 500 rpm for no less than 30 h can improve the ionic conductivity of the solid electrolyte material.

[0168] In combination with Example 2 and Comparative Examples 5-7, it can be seen that compared with halides such as ZrCl4, NbCl5, and TiCl3, the present disclosure utilizes tantalum halide and lithium nitride to form a ball mill at a ball milling speed of not less than 500 rpm for 30-300 hours according to a specific molar ratio, which can improve the ionic conductivity of the solid electrolyte material.

[0169] Test Example 2

[0170] The lithium-ion batteries 100 provided in Examples 8-11 were subjected to electrochemical performance tests such as discharge capacity and cycle performance.

[0171] The discharge capacity test curves of the lithium-ion battery 100 provided in Example 8 at different temperatures are shown in Figure 3 ; the cycling performance test curves of the lithium-ion battery 100 provided in Example 8 at -40°C are shown in Figure 4 ; and the cycling performance test curves of the lithium-ion battery 100 provided in Example 8 at -60°C are shown in Figure 5 . In the test data of Example 8, 0.1C and 0.02C refer to the charge and discharge currents, with 1C = 140 mA / g.

[0172] The cycle performance test curve of the lithium-ion battery 100 provided in Example 9 at -10°C is shown in FIG6 . 0.2C refers to the charge and discharge current, and 1C=140 mA / g.

[0173] The cycle performance test curve of the lithium-ion battery 100 provided in Example 10 at -30°C is shown in Figure 7. In the test data of Example 10, 0.1C refers to the charge and discharge current size, and 1C=100mA / g.

[0174] Among them, the charge and discharge test curve of the lithium ion battery 100 provided in Example 11 at 25°C and 0.1C is shown in Figure 8, where 0.1C refers to the charge and discharge current size, and 1C = 200mA / g; the charge and discharge test curve of the lithium ion battery 100 provided in Example 11 at 25°C and 2C is shown in Figure 9, where 2C refers to the charge and discharge current size, and 1C = 200mA / g; the first cycle charge and discharge test curve of the lithium ion battery 100 provided in Example 11 at -10°C is shown in Figure 10, where 0.1C refers to the charge and discharge current size, and 1C = 180mA / g.

[0175] Result analysis:

[0176] 3-7 , it can be seen that the combination of LiCoO2 and Li3TiCl6 positive electrode active materials with the solid electrolyte material provided in the examples of the present disclosure can improve the low-temperature electrochemical performance of the lithium-ion battery 100, so that the lithium-ion battery 100 still has good cycle performance and charge and discharge capacity at low temperatures of -40 to -10°C.

[0177] As can be seen from FIG8 , the battery can still be charged and discharged normally when the charging cut-off voltage is up to 4.7 V, indicating that the solid electrolyte material provided in the example of the present disclosure can withstand high voltage.

[0178] It can be clearly seen from FIG9 that the lithium-ion battery 100 can be normally charged and discharged 300 times at a current of 2C, indicating that the solid electrolyte material provided by the example of the present disclosure is relatively stable.

[0179] As can be seen from FIG10 , when the NCM811 positive electrode active material is used in combination with the solid electrolyte material provided in the examples of the present disclosure, the lithium-ion battery 100 cannot be charged normally at a low temperature of −10° C.

[0180] In summary, it can be seen from FIG. 3 to FIG. 9 that the solid electrolyte material provided in the examples of the present disclosure can be applied to the lithium-ion battery 100 and can improve the electrochemical performance of the lithium-ion battery.

[0181] 3 to 7 and 9 , it can be seen that, compared with positive electrode active materials such as NCM811, the use of the two positive electrode active materials Li3TiCl6 and LiCoO2 in combination with the solid electrolyte material provided in the examples of the present disclosure can improve the low-temperature electrochemical performance of the lithium-ion battery 100, so that the lithium-ion battery 100 still has good cycle performance and charge and discharge capacity at low temperatures of -40 to -10°C. Industrial Applicability

[0182] The present disclosure provides a solid electrolyte material and a preparation method thereof, wherein the chemical formula of the solid electrolyte material is Li3xTaA5Nx, 0.4≤x≤3, A is selected from F, Cl, Br or I, and has a good ionic conductivity of not less than 1.4mS cm-1, which can improve the electrochemical performance of lithium-ion batteries; in addition, the preparation method of the solid electrolyte material comprises ball milling lithium nitride and tantalum halide with a molar ratio of 0.43-0.67:1 for 30-300 hours in an inert gas environment with a water content and an oxygen content of not more than 0.01ppm at a ball milling speed of not less than 500rpm, thereby obtaining a heat-generating solid electrolyte material with high ionic conductivity, and further improving the ionic conductivity of the new solid electrolyte material while reducing ball milling energy consumption and improving preparation efficiency.

[0183] The present disclosure also provides a lithium battery, including a positive electrode, a solid electrolyte and a negative electrode that are set up once. The material of the positive electrode may include at least one of LiCoO2, Li3TiCl6 or Li4Ti5O12 and the solid electrolyte material obtained by the above preparation method, which can improve the low-temperature electrochemical performance of the lithium-ion battery, so that the lithium-ion battery still has good discharge capacity and cycle performance at low temperatures. The solid electrolyte includes a first electrolyte layer and a second electrolyte layer, wherein the first electrolyte layer is formed by the above-mentioned solid electrolyte material, and the material of the second electrolyte layer is selected from at least one of Li6PS5Cl or Li10GeP2S12. The material of the first electrolyte layer is matched with the material of the second electrolyte layer, which can improve the ionic conductivity of the solid electrolyte while also using the second electrolyte layer to separate the first solid electrolyte layer and the negative electrode to improve the interface stability between the solid electrolyte and the negative electrode, thereby further improving the electrochemical performance of the lithium-ion battery. The material of the negative electrode may include at least one of Sn, In, Li, Sb, Cu, Si, Ag-C, Li-In alloy, Fe3O4, TiO2, MnO, graphite, graphene, Li4Ti5O12 and the solid electrolyte material obtained by the above preparation method. The negative electrode is combined with the solid electrolyte and positive electrode provided above to improve the electrical performance of the lithium-ion battery.

[0184] The foregoing description is merely a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure.

Claims

1. A method for preparing a solid electrolyte material, characterized in that: include: In an inert gas environment with a water content and an oxygen content not higher than 0.01 ppm, lithium nitride and tantalum halide with a molar ratio of 0.4-3:1 are ball-milled at a ball-milling speed of not less than 500 rpm for 30-300 hours.

2. The preparation method according to claim 1, characterized in that The molar ratio of the lithium nitride to the tantalum halide is 0.43-0.67:

1.

3. The preparation method according to claim 1 or 2, characterized in that The ball milling time is 60-140h.

4. The preparation method according to any one of claims 1 to 3, characterized in that The tantalum halide may be selected from at least one of tantalum fluoride, tantalum chloride, tantalum bromide, and tantalum iodide.

5. The preparation method according to any one of claims 1 to 4, characterized in that Lithium nitride and tantalum halide were ball milled using a planetary ball mill.

6. The preparation method according to any one of claims 1 to 5, characterized in that Before the ball milling, lithium nitride and tantalum halide were put into a mortar and coarsely mixed for 10 minutes.

7. A solid electrolyte material prepared according to the preparation method according to any one of claims 1 to 6, wherein the chemical formula of the solid electrolyte material is Li3xTaA5Nx, 0.4≤x≤3, and A is selected from F, Cl, Br or I.

8. The solid electrolyte material according to claim 7, characterized in that The ionic conductivity of the solid electrolyte material is not less than 1.4 mS cm-1.

9. A lithium-ion battery, characterized in that: It comprises a negative electrode, a solid electrolyte and a positive electrode arranged in sequence, and the material forming the solid electrolyte comprises the solid electrolyte material according to claim 7 or 8.

10. The lithium-ion battery according to claim 9, characterized in that The material forming the solid electrolyte further includes a second solid electrolyte material.

11. The lithium-ion battery according to claim 10, wherein: The solid electrolyte includes a first electrolyte layer and a second electrolyte layer that are stacked. The solid electrolyte material forms the first electrolyte layer, and the second solid electrolyte material forms the second electrolyte layer. The second electrolyte layer is close to the negative electrode.

12. The lithium-ion battery according to claim 10 or 11, characterized in that The second solid electrolyte material is selected from at least one of a sulfide electrolyte material and a halide electrolyte material.

13. The lithium-ion battery according to claim 12, characterized in that The second solid electrolyte material is selected from at least one of Li6PS5Cl or Li10GeP2S12.

14. The lithium-ion battery according to any one of claims 10 to 13, characterized in that The mass ratio of the solid electrolyte material to the second solid electrolyte material is 2:

1.

15. The lithium-ion battery according to any one of claims 9 to 14, characterized in that The positive electrode active material of the positive electrode is selected from at least one of LiCoO2, Li3TiCl6 or Li4Ti5O12.

16. The lithium-ion battery according to claim 15, characterized in that The positive electrode active material of the positive electrode is selected from LiCoO2 or Li3TiCl6.

17. The lithium-ion battery according to claim 15 or 16, characterized in that: The material forming the positive electrode further includes the solid electrolyte material according to claim 7 or 8.

18. The lithium-ion battery according to any one of claims 9 to 17, characterized in that: The material forming the negative electrode includes at least one of Sn, In, Li, Sb, Cu, Si, Ag-C, Li-In alloy, Fe3O4, TiO2, MnO, graphite, graphene, and Li4Ti5O12.

19. The lithium-ion battery according to claim 18, wherein The material forming the negative electrode further includes the second solid electrolyte material.

20. The lithium-ion battery according to any one of claims 9 to 19, characterized in that The material forming the positive electrode further includes a conductive agent; the material forming the negative electrode further includes a conductive agent.

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