Doping modified sulfide electrolyte and preparation method thereof

Abstract

The invention provides a doped modified sulfide electrolyte and a preparation method thereof. The chemical general formula of the sulfide electrolyte is # imgabs0 #, wherein n represents the valence of M element, 2 < = n < = 6, 0 < = a < = 1, 0 < = b < = 1, and M comprises at least one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium and gallium elements; x comprises at least one of fluorine, chlorine, bromine and iodine elements. In the sulfide electrolyte, the M element is used for partially replacing the P site in the sulfide electrolyte, and the X element is used for partially replacing the S site in the sulfide electrolyte, so that the effects of reducing sulfur anions and sulfur-phosphorus tetrahedral groups in the sulfide electrolyte and improving the air stability of the sulfide electrolyte are achieved.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a doped and modified sulfide electrolyte and a preparation method thereof. Background Art

[0002] The limited energy density of lithium-ion batteries can no longer meet the high energy density demands of large-scale energy storage devices. All-solid-state batteries are considered one of the most ideal next-generation energy storage devices due to their excellent safety and huge potential for high energy density. Solid electrolytes play a key role in batteries and are favored by researchers. There are many types of electrolytes, including sulfides, oxides, and polymer electrolytes. Sulfide electrolytes have ionic conductivity close to that of liquid electrolytes at room temperature, and they also have advantages such as good flexibility and excellent mechanical properties, making them one of the best candidates for solid-state electrolytes.

[0003] However, sulfide electrolytes have poor air stability. Even a small amount of water in the environment will cause the decomposition and structural collapse of the sulfide electrolyte, resulting in a rapid decrease in ionic conductivity and the generation of toxic gas H2S. This requires the synthesis of sulfide electrolytes to be carried out in a low dew point environment (<-60°C) or in an inert atmosphere, which greatly increases the production cost and hinders its commercialization process.

[0004] In summary, improving the air stability of sulfide electrolytes is the key to current research. Summary of the Invention

[0005] The present invention provides a doped and modified sulfide electrolyte and a preparation method thereof, which are used to improve the air stability of the sulfide electrolyte.

[0006] In a first aspect of the present invention, a doped and modified sulfide electrolyte is provided, wherein the general chemical formula of the sulfide electrolyte is: ;

[0007] Wherein, n represents the valence of the element M, 2≤n≤6, 0≤a≤1, 0≤b≤1, M includes at least one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X includes at least one of fluorine, chlorine, bromine, and iodine.

[0008] According to one embodiment of the present invention, the M includes at least one of niobium, tantalum, tungsten and gadolinium.

[0009] According to one embodiment of the present invention, the X includes at least one of bromine and iodine elements.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned doped and modified sulfide electrolyte, comprising:

[0011] In an inert gas atmosphere, the raw materials of the sulfide electrolyte are mixed to obtain a precursor; the raw materials include Li2S, P2S and at least one MX n ; Wherein, n represents the valence of the element M, 2≤n≤6, M is any one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X is any one of fluorine, chlorine, bromine, and iodine;

[0012] The precursor is placed in an inert gas atmosphere for sintering to obtain the doped and modified sulfide electrolyte.

[0013] According to one embodiment of the present invention, the MX n It is any one of YCl3, YBr3, YF3, ZrCl4, ZrF4, NbF5, NbCl5, HfCl4, TaF5, TaCl5, TaBr5, WCl6, WBr6, WI6, GdCl3, GdBr3, GdF3, GaCl3, GaBr3, and GaF3.

[0014] According to one embodiment of the present invention, the MX in the raw material of the sulfide electrolyte is n The molar amount of the sulfide electrolyte is 0.1 to 30% of the molar amount of the prepared sulfide electrolyte.

[0015] According to one embodiment of the present invention, the sintering temperature is 200-600° C., and / or the sintering time is 4-24 hours.

[0016] According to one embodiment of the present invention, the raw materials of the sulfide electrolyte are mixed in an inert gas atmosphere to obtain a precursor, comprising:

[0017] In an inert gas atmosphere, the raw materials of the sulfide electrolyte are added to a solvent, fully mixed, and then dried to obtain the precursor; wherein the solvent is at least one of toluene, xylene, heptane, carbon tetrachloride, isobutyl isobutyrate, tetrahydrofuran, acetonitrile, n-butanol, isopropanol, and ethanol, and / or the drying temperature is 50 to 150° C., and / or the drying time is 5 to 24 hours.

[0018] According to one embodiment of the present invention, the raw materials of the sulfide electrolyte are mixed in an inert gas atmosphere to obtain a precursor, comprising:

[0019] In an inert gas atmosphere, ball-milling and mixing the raw materials of the sulfide electrolyte to obtain the precursor;

[0020] Wherein, the rotation speed of the ball milling mixing treatment is 200-750 rpm, and / or the time is 2-24 hours.

[0021] According to one embodiment of the present invention, the inert gas includes at least one of nitrogen, argon, helium and neon.

[0022] A third aspect of the present invention provides an all-solid-state battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte;

[0023] The electrolyte is the doped and modified sulfide electrolyte described in the first aspect, or the doped and modified sulfide electrolyte prepared by the method described in the second aspect.

[0024] A fourth aspect of the present invention is an electrical device comprising an electrical device body and the all-solid-state battery described in the third aspect.

[0025] The implementation of the present invention has at least the following beneficial effects:

[0026] In the sulfide electrolyte, the M element is used to partially replace the P site in the sulfide electrolyte, and the X element is used to partially replace the S site in the sulfide electrolyte, thereby reducing the sulfur anions in the sulfide electrolyte ( ) and sulfur phosphorus tetrahedron ( ) groups, thereby avoiding the hydrolysis reaction of sulfur anions and sulfur-phosphorus tetrahedrons to a certain extent, thereby achieving the effect of improving the air stability of sulfide electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] Figure 1 A schematic flow chart of a method for preparing a doped and modified sulfide electrolyte is provided for Example 2 of the present invention.

[0029] The above drawings illustrate specific embodiments of the present invention, which will be described in more detail below. These drawings and the accompanying description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concepts of the present invention for those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0031] Based on the introduction of the above background technology, the first embodiment of the present invention provides a doped and modified sulfide electrolyte, the chemical formula of the sulfide electrolyte is: ;

[0032] Wherein, n represents the valence of the element M, 2≤n≤6, 0≤a≤1, 0≤b≤1, M includes at least one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X includes at least one of fluorine, chlorine, bromine, and iodine.

[0033] According to the inventors’ research, the sulfur anions (S 2- ) has a strong Lewis base, and the H + It is a Lewis acid, and the two undergo a proton exchange reaction, releasing highly toxic H2S gas; the sulfur-phosphorus tetrahedron in the sulfide electrolyte ( ) group hydrolyzes, the PS bond breaks, and the structure collapses into amorphous phosphorus / sulfur oxides (such as LiOH, Li2CO3, Li3PO4, etc.), resulting in the appearance of insulating impurities in the electrolyte. Therefore, the present invention partially replaces the P position in the sulfide electrolyte with a metal M element (such as yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, gallium, etc.), and partially replaces the S position in the sulfide electrolyte with a halogen X element (such as fluorine, chlorine, bromine, iodine, etc.), thereby obtaining a doped sulfide electrolyte Li 3+b(5-n) P 1-b M b S 4-0.5a X a .

[0034] Among them, the doped modified sulfide electrolyte has relatively few sulfur anions and sulfur-phosphorus tetrahedral groups, making it more tolerant to humid air and thus having higher structural stability. Therefore, even if the sulfide electrolyte is exposed to a relatively high humidity environment (for example, a dew point of -50°C), the sulfide electrolyte has a high ionic conductivity retention rate. Furthermore, the all-solid-state battery prepared using this sulfide electrolyte in a relatively high humidity environment also has excellent cycle performance, thereby reducing the production cost of sulfide all-solid-state batteries.

[0035] In addition, according to further research by the inventors, the above-mentioned doping can also effectively improve the electrochemical performance of sulfide electrolytes. Compared with the S element, the ionic radius of halogen elements is larger, and compared with the P element, the ionic radius of metal elements is also larger. Therefore, using halogen elements to partially replace the S position and using metal elements to replace the P position is beneficial to expand the lattice distance in the sulfide electrolyte, expand the lithium ion migration channel, thereby promoting the migration of lithium ions, thereby reducing the activation energy and achieving the effect of improving the ionic conductivity of the electrolyte. At the same time, using halogen elements to partially replace the S element in the electrolyte can reduce the volatilization of sulfur elements during the high-temperature synthesis of sulfide electrolytes, thereby improving the phase purity of the electrolyte.

[0036] In summary, compared with the original sulfide electrolyte, the doped-modified sulfide electrolyte of the present invention has stronger air stability, higher ionic conductivity, higher phase purity and higher ionic conductivity retention; at the same time, the all-solid-state battery prepared using the doped-modified sulfide electrolyte also has higher ionic conductivity and good cycle performance.

[0037] In some possible embodiments, M preferably includes at least one of niobium, tantalum, tungsten, and gadolinium. It should be understood that niobium, tantalum, tungsten, and gadolinium have valences or ionic radii closer to those of phosphorus, which can reduce lattice distortion in the sulfide electrolyte caused by element substitution.

[0038] In some possible embodiments, X preferably comprises at least one of bromine and iodine. It should be understood that bromine or iodine have larger ionic radii, and their partial substitution for S can significantly expand ion channels, thereby enhancing the ionic conductivity of the sulfide electrolyte.

[0039] In the doped modified sulfide electrolyte provided by the embodiment of the present invention, the M element is used to partially replace the P site in the sulfide electrolyte, and the X element is used to partially replace the S site in the sulfide electrolyte, thereby reducing the sulfur anion (S 2- ) and sulfur phosphorus tetrahedron ( ) groups, thereby avoiding the hydrolysis reaction of sulfur anions and sulfur-phosphorus tetrahedrons to a certain extent, thereby achieving the effect of improving the air stability of sulfide electrolytes.

[0040] Figure 1 A schematic flow chart of a method for preparing a doped modified sulfide electrolyte is provided for Example 2 of the present invention. The preparation method provided by the present invention is used to prepare the doped modified sulfide electrolyte described in Example 1 above. Figure 1 As shown, including:

[0041] S101, in an inert gas atmosphere, mixing raw materials of a sulfide electrolyte to obtain a precursor, wherein the raw materials of the sulfide electrolyte include Li2S, P2S and at least one MX n .

[0042] Wherein, n represents the valence of the element M, 2≤n≤6, M is any one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X is any one of fluorine, chlorine, bromine, and iodine.

[0043] In this step, a certain amount of Li2S, P2S and at least one MXene is weighed in an inert gas atmosphere according to the stoichiometric ratio of each raw material. n , and adopt dry or wet method to mix Li2S, P2S and at least one MX n The precursor is obtained by mixing.

[0044] In a possible embodiment, if a dry method is used for raw material mixing, the raw materials of the sulfide electrolyte are added to a solvent in an inert gas atmosphere, mixed thoroughly, and then dried to obtain a precursor.

[0045] Alternatively, the method for fully mixing may be to add the raw materials into the solvent and then fully mix them by ball milling.

[0046] The solvent is at least one of toluene, xylene, heptane, carbon tetrachloride, isobutyl isobutyrate, tetrahydrofuran, acetonitrile, n-butanol, isopropyl alcohol, and ethanol. Specifically, the solvent can be any one of toluene, xylene, heptane, carbon tetrachloride, isobutyl isobutyrate, tetrahydrofuran, acetonitrile, n-butanol, isopropyl alcohol, and ethanol, or can be a combination of any multiple of the above substances, for example, a combination of two, three, or more substances, which is not specifically limited in this embodiment of the present invention.

[0047] Optionally, the drying temperature may be 50 to 150° C., and / or the drying time may be 5 to 24 hours.

[0048] Illustratively, the drying temperature is, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range; and / or the time is, for example, 5h, 7h, 9h, 11h, 13h, 15h, 17h, 19h, 21h, 23h, 24h, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range.

[0049] It should be understood that the purpose of the drying process is to volatilize the solvent.

[0050] In one possible embodiment, if a dry method is used for raw material mixing, the raw materials of the sulfide electrolyte are subjected to a ball milling mixing process in an inert gas atmosphere to obtain a precursor;

[0051] The ball milling mixing process is performed at a rotation speed of 200 to 750 rpm and / or for a time of 2 to 24 hours.

[0052] Illustratively, the rotation speed of the ball milling mixing process is, for example, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range; and / or the time is 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range.

[0053] Optional, MX n It is any one of YCl3, YBr3, YF3, ZrCl4, ZrF4, NbF5, NbCl5, HfCl4, TaF5, TaCl5, TaBr5, WCl6, WBr6, WI6, GdCl3, GdBr3, GdF3, GaCl3, GaBr3, and GaF3.

[0054] It should be understood that the raw materials of the sulfide electrolyte include at least one MX n , for each MX n , which is any one of YCl3, YBr3, YF3, ZrCl4, ZrF4, NbF5, NbCl5, HfCl4, TaF5, TaCl5, TaBr5, WCl6, WBr6, WI6, GdCl3, GdBr3, GdF3, GaCl3, GaBr3, and GaF3. Specifically, it can include any one of YCl3, YBr3, YF3, ZrCl4, ZrF4, NbF5, NbCl5, HfCl4, TaF5, TaCl5, TaBr5, WCl6, WBr6, WI6, GdCl3, GdBr3, GdF3, GaCl3, GaBr3, and GaF3. It can also include any combination of multiple substances among the above substances, for example, it can include two, three or more substances, which is not specifically limited in this embodiment of the present invention.

[0055] In one possible embodiment, the MX in the raw material of the sulfide electrolyte is nThe molar amount of the sulfide electrolyte is 0.1 to 30% of the molar amount of the prepared sulfide electrolyte.

[0056] For example, MX in the raw materials of sulfide electrolyte n The molar amount is 0.1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30% of the molar amount of the prepared sulfide electrolyte, or any two of the foregoing values ​​are selected to form a new range, and the value taken within the new range.

[0057] S102, placing the precursor in an inert gas atmosphere for sintering to obtain a doped and modified sulfide electrolyte.

[0058] In this step, the precursor needs to be sintered in an inert gas atmosphere to obtain a doped and modified sulfide electrolyte.

[0059] Among them, the chemical formula of sulfide electrolyte is: Li 3+b(5-n) P 1-b M b S 4-0.5a X a , n represents the valence of the element M, 2≤n≤6, 0≤a≤1, 0≤b≤1, M includes at least one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X includes at least one of fluorine, chlorine, bromine, and iodine.

[0060] Optionally, the inert gas includes at least one of nitrogen, argon, helium, and neon.

[0061] Specifically, the inert gas is any one of nitrogen, argon, helium, and neon, and can also be composed of any combination of multiple substances among the above substances, for example, it can be composed of two, three or more substances. This embodiment of the present invention does not specifically limit this.

[0062] In a possible implementation, the sintering temperature is 200-600° C., and / or the sintering time is 4-24 hours.

[0063] It should be understood that the sintering temperature and time when preparing sulfide electrolytes are key factors affecting the quality of the prepared electrolyte product and the production efficiency of the product. In practical applications, the sintering temperature and time can be adjusted according to the specific application.

[0064] For example, the sintering temperature is, for example, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range; and / or the time is 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any two of the foregoing values ​​are selected to form a new range, and the values ​​taken within the new range.

[0065] The preparation method provided by the embodiment of the present invention comprises: firstly preparing Li2S, P2S and at least one MX n After mixing the raw materials of the sulfide electrolyte and performing sintering treatment, a doped-modified sulfide electrolyte with high air stability and high ionic conductivity is obtained, which provides a basis for preparing all-solid-state batteries with excellent cycle stability performance.

[0066] Embodiment 3 of the present invention provides an all-solid-state battery, comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte; wherein the electrolyte is the doped-modified sulfide electrolyte of embodiment 1, or the doped-modified sulfide electrolyte prepared by the method of embodiment 2.

[0067] The positive electrode sheet specifically includes a positive electrode current collector and a positive electrode active layer formed of a positive electrode active material disposed on the surface of the positive electrode current collector. It should be understood that the present invention is not strictly limited to the positive electrode active material in the positive electrode sheet, and can be any positive electrode active material commonly used in lithium-ion batteries, such as at least one composite oxide of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof. Specifically, it can be at least one of lithium cobaltate, lithium nickelate, lithium manganate, a nickel-cobalt-manganese ternary material, a nickel-cobalt-aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganate, and a lithium-rich manganese-based material.

[0068] Furthermore, the negative electrode sheet specifically includes a negative electrode current collector and a negative electrode active layer formed of a negative electrode active material disposed on the surface of the negative electrode current collector. It should be understood that the present invention is not strictly limited to the negative electrode active material in the negative electrode sheet; it can be at least one of the negative electrode active materials commonly used in lithium-ion batteries, such as graphite, hard carbon, soft carbon, mesocarbon microbeads, silicon-based negative electrode materials (primarily including silicon monoxide and silicon-carbon negative electrodes), and tin-based negative electrode materials (primarily including tin and tin alloys).

[0069] As a specific example, the doped modified sulfide electrolyte provided by the present invention can be made into a powder, and then mixed with a binder to form an electrolyte layer; and the positive electrode sheet, the electrolyte layer and the negative electrode sheet can be stacked in sequence and pressurized to form an all-solid-state battery.

[0070] In the all-solid-state battery provided in this embodiment, the sulfide electrolyte used has high air stability and is not easily decomposed when exposed to an environment with relatively high humidity. Therefore, the all-solid-state battery can not only be prepared in a low-cost humidity environment, but also has excellent cycle stability.

[0071] A fourth embodiment of the present invention provides an electrical device, comprising an electrical device body and the all-solid-state battery provided by the present invention.

[0072] It should be noted that the present invention does not specifically limit the type of electrical device, which can be any electrical device that includes the battery, including but not limited to electric vehicles, mobile phones, portable devices, laptops, electric bicycles, electric toys, energy storage devices, etc.

[0073] The present invention is further described below through specific examples.

[0074] Example 1

[0075] Preparation of sulfide electrolyte:

[0076] In an inert gas atmosphere, acetonitrile was used as a solvent, 6.6680 g of Li2S, 9.0720 g of P2S5 and 4.2600 g of YI3 were weighed and dissolved in the solvent, placed in a ball mill, ball milled at 500 rpm for 12 h, and dried at 70 ° C for 12 h to obtain a precursor; the precursor was sintered at 280 ° C for 8 h in an inert gas atmosphere to obtain a doped modified sulfide electrolyte Li 3.2 P 0.9 Y 0.1 S 3.85 I 0.3 .

[0077] Example 2

[0078] Preparation of sulfide electrolyte:

[0079] In an inert gas atmosphere, 6.2831 g of Li2S, 8.5483 g of P2S5, 4.0140 g of YI3 and 1.1546 g of NbCl5 were weighed in a ball mill and milled at 600 rpm for 10 h to obtain a precursor; the precursor was sintered at 300 ° C for 6 h in an inert gas atmosphere to obtain a doped sulfide electrolyte Li 3.2 P 0.9 Y 0.1 Nb 0.05 S 3.725 Cl 0.25 I 0.3 .

[0080] Example 3

[0081] Preparation of sulfide electrolyte:

[0082] In an inert gas atmosphere, 7.5032 g of Li2S, 11.5056 g of P2S5, 0.5743 g of GdI3 and 0.4169 g of YCl3 were weighed in a ball mill and ball milled at 650 rpm for 9 h to obtain a precursor; the precursor was sintered at 320 ° C for 5 h in an inert gas atmosphere to obtain a doped sulfide electrolyte Li 3.06 P 0.97 Gd 0.01 Y 0.02 S 3.955 I 0.03 Cl 0.06 .

[0083] Example 4

[0084] Preparation of sulfide electrolyte:

[0085] In an inert gas atmosphere, 7.0255 g of Li2S, 9.7257 g of P2S5, 1.0582 g of GdI3, 0.9695 g of YBr3, 0.1644 g of ZrF4 and 1.0566 g of TaCl5 were weighed in a ball mill and milled at 700 rpm for 8 h to obtain a precursor; the precursor was sintered at 270 ° C for 10 h in an inert gas atmosphere to obtain a doped sulfide electrolyte Li 3.11 P 0.91 Gd 0.02 Y 0.03 Ta 0.03 Zr 0.01 S 3.84 Cl 0.15 I 0.04 Br 0.09 F 0.04。

[0086] Comparative Example

[0087] Preparation of sulfide electrolyte:

[0088] In an inert gas atmosphere, 7.6556 g of Li2S and 12.3444 g of P2S5 were weighed into a ball mill and ball milled at 650 rpm for 10 h to obtain a precursor; the precursor was sintered at 300 ° C for 6 h in an inert gas atmosphere to obtain the sulfide electrolyte Li3PS4.

[0089] The sulfide electrolytes prepared in the above examples and comparative examples were subjected to performance tests, and the test contents specifically included:

[0090] 1. The sulfide electrolytes prepared in Examples 1 to 4 and the comparative example were tested for ionic conductivity and air stability. The test results are shown in Table 1. The test contents include:

[0091] The ionic conductivity of the sulfide electrolyte was tested after exposure to a low-humidity room at a dew point of -50°C for 0 and 1 hour. The ionic conductivity test method involves weighing 150 mg of sulfide electrolyte powder and placing it in a battery mold (10 mm inner diameter). A pressure of 400 MPa was applied, and the AC impedance was measured using an electrochemical workstation. After applying an applied voltage of 10 mV over a frequency range of 1 Hz to 7 MHz, the ionic conductivity of the sulfide electrolyte was calculated.

[0092] The ionic conductivity retention of the sulfide electrolyte was calculated based on the ionic conductivity of the sulfide electrolyte at 0 h exposure and the ionic conductivity after 1 h exposure.

[0093] Table 1: Ionic conductivity and air stability test results of sulfide electrolytes

[0094]

[0095] 2. The sulfide electrolytes obtained in the above embodiments and comparative examples, which were exposed to a dew point environment of -50°C for 1 hour, were used to prepare all-solid-state batteries. The electrochemical performance of the all-solid-state batteries was tested, and the test results are shown in Table 2.

[0096] The method for preparing an all-solid-state battery includes:

[0097] (1) Preparation of positive electrode:

[0098] The positive electrode material, the electrolyte exposed for 1 hour, the conductive agent (VGCF), and the binder (PTFE) were mixed in a mass ratio of 70:30:2:0.5 to prepare a positive electrode active layer; the positive electrode active layer was compounded with stainless steel to form a positive electrode sheet.

[0099] (2) Using lithium metal as the negative electrode.

[0100] (3) Preparation of solid electrolyte layer:

[0101] The sulfide electrolyte exposed to a dew point environment of -50°C for 1 hour was fully mixed with a binder (PTFE) at a mass ratio of 100:0.5 to prepare an electrolyte membrane.

[0102] (4) Assembly of all-solid-state batteries:

[0103] The above-mentioned positive electrode sheet, negative electrode sheet and solid electrolyte layer are assembled to obtain an all-solid-state battery.

[0104] Among them, the electrochemical performance testing methods for all-solid-state batteries include:

[0105] (1) First charge and discharge test: The all-solid-state battery is charged and discharged for one cycle at 0.1C constant current at 25°C with a voltage range of 2.7-4.3V. The first charge and discharge specific capacity and first charge and discharge efficiency of the battery are calculated based on the test results.

[0106] 2) Long cycle test: The all-solid-state battery is charged and discharged for 100 cycles at a constant current of 0.1C at 25°C with a voltage range of 2.7-4.3V. Based on the test results, the specific capacity of the battery after 100 cycles and the capacity retention rate after 100 cycles are calculated.

[0107] Table 2: Electrochemical performance test results of all-solid-state batteries

[0108]

[0109] According to the test results in Table 1, it can be seen that compared with the comparative example, the ionic conductivity of the sulfide electrolytes corresponding to Examples 1-4 that have not been exposed to a dew point environment of -50°C is significantly higher, which shows that the doped modified sulfide electrolytes provided by the present invention have higher ionic conductivity; in addition, the ionic conductivity retention rate of the sulfide electrolytes corresponding to Examples 1-4 is also significantly higher than that of the comparative example, which shows that the air stability of the doped modified sulfide electrolytes provided by the present invention is significantly better than that of the unmodified material, and the electrolyte in the present invention still has a high ionic conductivity after exposure for 1 hour.

[0110] From the test results in Table 2, it can be seen that compared with the comparative example, the first discharge specific capacity, first coulombic efficiency, and capacity retention rate after 100 cycles of the all-solid-state batteries corresponding to Examples 1-4 are significantly better. It can be seen that the doped modified sulfide electrolyte provided by the present invention can effectively improve the electrochemical performance of the battery, including cycle stability.

[0111] In summary, the doped sulfide electrolyte obtained by partially replacing the P position with the M element and partially replacing the S position with the X element in the present invention improves the air stability and ionic conductivity of the sulfide electrolyte, and improves the cycle performance of the all-solid-state battery prepared using the sulfide electrolyte.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A doped modified sulfide electrolyte, characterized in that: The general chemical formula of the sulfide electrolyte is: ; Wherein, n represents the valence of the element M, 2≤n≤6, 0≤a≤1, 0≤b≤1, M includes at least one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X includes at least one of fluorine, chlorine, bromine, and iodine.

2. The sulfide electrolyte according to claim 1, characterized in that The M includes at least one of niobium, tantalum, tungsten and gadolinium.

3. The sulfide electrolyte according to claim 1 or 2, characterized in that The X includes at least one of bromine and iodine elements.

4. A method for preparing a doped and modified sulfide electrolyte according to any one of claims 1 to 3, characterized in that: include: In an inert gas atmosphere, the raw materials of the sulfide electrolyte are mixed to obtain a precursor; the raw materials include Li2S, P2S and at least one MX n ; Wherein, n represents the valence of the element M, 2≤n≤6, M is any one of yttrium, zirconium, niobium, hafnium, tantalum, tungsten, gadolinium, and gallium; X is any one of fluorine, chlorine, bromine, and iodine; The precursor is placed in an inert gas atmosphere for sintering to obtain the doped and modified sulfide electrolyte.

5. The method according to claim 4, characterized in that The MX n It is any one of YCl3, YBr3, YF3, ZrCl4, ZrF4, NbF5, NbCl5, HfCl4, TaF5, TaCl5, TaBr5, WCl6, WBr6, WI6, GdCl3, GdBr3, GdF3, GaCl3, GaBr3, and GaF3.

6. The method according to claim 5, characterized in that The MX in the raw materials of the sulfide electrolyte n The molar amount of the sulfide electrolyte is 0.1 to 30% of the molar amount of the prepared sulfide electrolyte.

7. The method according to claim 4, characterized in that The sintering temperature is 200-600° C., and / or the sintering time is 4-24 hours.

8. The method according to claim 4, characterized in that The raw materials of the sulfide electrolyte are mixed in an inert gas atmosphere to obtain a precursor, comprising: In an inert gas atmosphere, the raw materials of the sulfide electrolyte are added to a solvent, fully mixed, and then dried to obtain the precursor; wherein the solvent is at least one of toluene, xylene, heptane, carbon tetrachloride, isobutyl isobutyrate, tetrahydrofuran, acetonitrile, n-butanol, isopropanol, and ethanol, and / or the drying temperature is 50 to 150° C., and / or the drying time is 5 to 24 hours.

9. The method according to claim 4, characterized in that The raw materials of the sulfide electrolyte are mixed in an inert gas atmosphere to obtain a precursor, comprising: In an inert gas atmosphere, ball-milling and mixing the raw materials of the sulfide electrolyte to obtain the precursor; Wherein, the rotation speed of the ball milling mixing treatment is 200-750 rpm, and / or the time is 2-24 hours.

10. The method according to any one of claims 4 to 9, characterized in that The inert gas includes at least one of nitrogen, argon, helium and neon.

11. An all-solid-state battery, characterized in that: include: Positive electrode, negative electrode and electrolyte; The electrolyte is the doped and modified sulfide electrolyte according to any one of claims 1 to 3, or the doped and modified sulfide electrolyte prepared by the method according to any one of claims 4 to 10.

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