Preparation method of sulfide solid electrolyte and solid-state battery

Abstract

The embodiment of the invention provides a preparation method of sulfide solid electrolyte and a solid-state battery, and relates to the technical field of batteries. The method comprises the following steps: carrying out preliminary mixing on Li2S, P2S5 and ZnCl2 to obtain mixed powder, carrying out non-crystallization treatment on the mixed powder to obtain a solid electrolyte powder precursor, and carrying out high-temperature sintering on the solid electrolyte powder precursor in inert gas to obtain the sulfide solid electrolyte. According to the method, the prepared sulfide solid electrolyte has high ionic conductivity and good interface stability, so that the performance and the reliability of the solid-state battery are improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for preparing a sulfide solid electrolyte and a solid-state battery. Background Art

[0002] All-solid-state lithium-ion batteries are considered to be one of the core directions of the next generation of energy storage technology due to their high energy density, excellent safety and long cycle life. Sulfide solid electrolytes among solid electrolytes have become a current research hotspot due to their ultra-high lithium ion conductivity, good mechanical ductility and interface compatibility with electrode materials.

[0003] In view of the problems of traditional sulfide electrolytes such as Li3PS4 that they easily react with moisture in the air to generate toxic H2S, have a narrow electrochemical window and are prone to interfacial side reactions, element doping strategies are widely used to optimize the comprehensive performance of sulfide electrolytes. Existing doping technologies such as oxygen doping and bromine doping can improve the performance of electrolytes to a certain extent, but there are still difficulties in optimizing ionic conductivity and interface stability at the same time.

[0004] In summary, providing an element doping technology solution that optimizes electrolyte ion conductivity while ensuring interface stability is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present application provide a method for preparing a sulfide solid electrolyte and a solid-state battery, which are used to improve the ionic conductivity of the electrolyte while ensuring interface stability.

[0006] In a first aspect, an embodiment of the present application provides a method for preparing a sulfide solid electrolyte, the method comprising:

[0007] Preliminarily mix Li2S, P2S5 and ZnCl2 to obtain a mixed powder;

[0008] Performing an amorphization treatment on the mixed powder to obtain a solid electrolyte powder precursor;

[0009] The solid electrolyte powder precursor is sintered at high temperature under an inert gas to obtain a sulfide solid electrolyte.

[0010] In one possible embodiment, the molecular formula of the sulfide solid electrolyte is Li 3+x P 1-x Zn x S 4- 2x Cl 2x , where the value range of x is 0 <x<0.1。

[0011] In a possible implementation, the value range of x is 0.01 ≦ x ≦ 0.08.

[0012] In a possible implementation, before initially mixing Li2S, P2S5, and ZnCl2 to obtain a mixed powder, the method further includes:

[0013] Weigh Li2S, P2S5, and ZnCl2 according to the molar ratio of Li2S, P2S5, and ZnCl2 being (3.01 - 3.08):(0.92 - 0.99):(0.02 - 0.16).

[0014] In a possible implementation, the initial mixing method includes dry mixing or wet mixing.

[0015] In a possible implementation, the initial mixing method is mechanical mixing in dry mixing.

[0016] In a possible implementation, the non - crystallization treatment of the mixed powder to obtain a precursor of the solid electrolyte powder includes:

[0017] Place the mixed powder in a ball - milling jar and perform ball - milling treatment using a ball mill to obtain the precursor of the solid electrolyte powder.

[0018] In a possible implementation, the ball - milling speed during the ball - milling treatment is 100 - 800 rpm, and the ball - milling time is 10 - 50 h.

[0019] In a possible implementation, the ball - milling speed during the ball - milling treatment is 500 - 800 rpm, and the ball - milling time is 30 - 40 h.

[0020] In a possible implementation, during high - temperature sintering, the high - temperature sintering temperature is 200 - 400 °C, and the high - temperature sintering time is 5 - 10 h.

[0021] In a possible implementation, the value range of the average particle size D50 of Li2S is 3 ≦ D50 ≦ 50 .

[0022] In a possible implementation, the value range of the average particle size D50 of Li2S is 3 ≦ D50 ≦ 10 .

[0023] In a second aspect, an electrolyte provided by an embodiment of the present application includes: the sulfide solid electrolyte described in the first aspect.

[0024] In a third aspect, an embodiment of the present application provides a solid-state battery, including a positive electrode, a negative electrode, and the electrolyte described in the second aspect.

[0025] In a fourth aspect, an embodiment of the present application provides an electrical device, including a device main body and the solid-state battery described in the third aspect.

[0026] For the preparation method of the sulfide solid electrolyte and the solid-state battery provided by the embodiments of the present application, after initially mixing Li2S, P2S5, and ZnCl2 to obtain a mixed powder, the mixed powder is subjected to an amorphization treatment to obtain a precursor of the solid electrolyte powder, and then the precursor of the solid electrolyte powder is sintered at a high temperature under an inert gas to obtain the sulfide solid electrolyte. Through the above method, the prepared sulfide solid electrolyte has high ionic conductivity and good interfacial stability, thereby improving the performance and reliability of the solid-state battery. Description of the Drawings

[0027] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0028] Figure 1 It is a schematic flowchart of a method for preparing a sulfide solid electrolyte provided by the present application.

[0029] Through the above drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and the textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed Embodiments

[0030] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0031] First, the application background of the present application is explained as follows:

[0032] All-solid-state lithium-ion batteries are considered one of the core directions for next-generation energy storage technologies due to their high energy density, excellent safety, and long cycle life. As a key component of all-solid-state batteries, solid electrolytes directly affect the performance and commercialization potential of the batteries. Sulfide solid electrolytes have become a current research hotspot due to their ultra-high lithium-ion conductivity (up to the order of 10 mS / cm, approaching that of liquid electrolytes), good mechanical ductility, and interfacial compatibility with electrode materials.

[0033] Traditional sulfide electrolytes, such as Li3PS4, Li7P3S 11 have relatively good lithium-ion conductivity. For example, the conductivity of Li3PS4 can reach 10 -4 -10 -3 S / cm. However, their air stability is poor, they are prone to react with moisture in the air to generate toxic H2S, are easily oxidized by high-voltage cathodes, and are prone to chemical reactions at the interface with electrode materials during battery charge and discharge, generating non-conductive by-products and increasing impedance. In response to the challenges faced by traditional sulfide electrolytes, such as insufficient chemical stability, narrow electrochemical window, and interfacial side reactions, element doping strategies have been widely adopted to optimize the comprehensive performance of sulfide electrolytes.

[0034] Existing doping technologies, such as single oxygen doping and single bromine doping, although they can improve the performance of electrolytes to a certain extent, still face difficulties in simultaneously optimizing ionic conductivity and interfacial stability. On the one hand, oxygen doping technology can enhance the antioxidant ability of electrolytes to a certain extent by introducing oxygen elements and reduce reactions with moisture and oxygen in the air. However, the introduction of oxygen may change the crystal structure of the electrolyte, thereby affecting the migration path of lithium ions and resulting in a decrease in ionic conductivity because oxides generally have lower ionic conductivity than sulfides. On the other hand, bromine doping technology can adjust the electronic structure of the electrolyte to make it stable at higher voltages. However, bromine doping may complicate the chemical reactions at the interface, especially when in contact with high-voltage cathode materials, leading to an increase in interfacial side reactions, generating non-conductive by-products, thus increasing the interfacial impedance and affecting the cycle performance of the battery. Therefore, single oxygen doping and single bromine doping can improve the performance of sulfide electrolytes in some aspects, but still face difficulties in simultaneously optimizing ionic conductivity and interfacial stability.

[0035] In summary, providing an element doping technical solution that optimizes the ionic conductivity of the electrolyte while ensuring interfacial stability, and thus improving battery performance, is a technical solution that urgently needs to be solved.

[0036] Based on the above technical problems, during the research on sulfide solid electrolytes, the inventors found that by using the co-doping technology of zinc (Zn) and chlorine (Cl) on Li3PS4 with a relatively high lithium ion conductivity, it is possible to optimize the ionic conductivity of the electrolyte while ensuring the interface stability. Specifically, on the one hand, there are differences in the atomic radii of zinc atoms and atoms such as lithium and phosphorus. After doping, the crystal structure of Li3PS4 can be distorted, providing more transmission channels and transition sites for lithium ions, which helps the rapid migration of lithium ions in the crystal structure, thereby improving the ionic conductivity. On the other hand, by doping halogen elements into Li3PS4, a lithium halide layer can be formed on the surface of lithium metal during the electrochemical process, and then a stable interface can be formed. Based on this, the present application provides a preparation method of a sulfide solid electrolyte and a solid-state battery.

[0037] The following uses specific examples to elaborate in detail on the technical solutions of the present application and how the technical solutions of the present application solve the above technical problems. These specific examples below can be combined with each other, and the same or similar concepts or processes may not be repeated in some examples. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0038] Figure 1 It is a schematic flow chart of a preparation method of a sulfide solid electrolyte provided by the present application. As Figure 1 shown, the method includes:

[0039] S101: Initially mix Li2S, P2S5, and ZnCl2 to obtain a mixed powder.

[0040] In this step, lithium sulfide (Li2S) is a compound composed of lithium and sulfur, commonly used in solid electrolyte materials, which is a source of lithium ions and provides lithium ion conductivity in the electrolyte; phosphorus pentasulfide (P2S5) is a compound of phosphorus and sulfur, commonly used in the synthesis of sulfide electrolytes; zinc chloride (ZnCl2) is a chloride of zinc, which is introduced into the electrolyte as a dopant.

[0041] In a possible implementation manner, the initial mixing method includes dry mixing or wet mixing. Preferably, the initial mixing method is mechanical mixing in dry mixing.

[0042] Dry mixing refers to directly mixing powder materials without a liquid medium. Mechanical mixing is a common form of dry mixing, that is, using mechanical equipment such as ball mills, mixers or blenders to uniformly mix powder materials. Wet mixing refers to mixing powder materials with a liquid solvent to form a slurry, and subsequent drying steps are required to remove the solvent.

[0043] In a possible implementation manner, the value range of the average particle size D50 of Li2S is 3 3 ≤ D50 ≤ 50 Preferably, the average particle size D50 of Li2S ranges from 3 ≤ D50 ≤ 10 .

[0044] The average particle size of Li2S is between 3 and 50 , especially in the range of 3 to 10 . This helps to optimize the fluidity and dispersibility of the powder, which is crucial for the mixing of Li2S with other materials and the subsequent sintering process. A smaller particle size can provide a larger specific surface area, promoting the uniformity of the reaction and the densification of the material. In addition, the present application does not specifically limit the purity and shape of Li2S, and its shape can be spherical, polygonal, irregular, etc. Regarding purity, from the perspective of preparing a high-purity sulfide solid electrolyte, the higher the purity of Li2S, the better.

[0045] In this solution, specifically, Li2S, P2S5, and ZnCl2 are weighed according to the molar ratio of (3.01 - 3.08):(0.92 - 0.99):(0.02 - 0.16) to obtain Li2S, P2S5, and ZnCl2, and they are mixed by mechanical mixing to obtain a mixed powder. The mechanical mixing method pre-disperses the Li2S, P2S5, and ZnCl2 powders, which is beneficial to the uniformity of amorphization during the subsequent ball milling process.

[0046] Li2S is the main source of lithium ions. P2S5 reacts with Li2S to form a sulfide matrix, and ZnCl2 is used as a dopant to improve the interfacial stability and chemical stability of the electrolyte. Excessive Li2S may cause instability of the electrolyte structure, leading to a decrease in its mechanical properties; while too little Li2S may result in insufficient lithium ion concentration, reducing the ionic conductivity and thus affecting the overall performance of the battery. Excessive P2S5 may lead to the formation of too much sulfide matrix, affecting the conductivity and mechanical properties of the material; while too little P2S5 may result in an incomplete matrix, affecting the structural integrity and stability of the material. Excessive ZnCl2 may lead to over-doping, affecting the crystal structure and ion migration path of the electrolyte, thus reducing the ionic conductivity; while too little ZnCl2 may not be sufficient to effectively inhibit interfacial side reactions, resulting in poor interfacial stability.

[0047] Exemplarily, the molar ratio of Li2S, P2S5, and ZnCl2 can be 3.01:0.92:0.02 or 3.05:0.95:0.09 or 3.07:0.93:0.10 or 3.08:0.99:0.16, etc. Here, it is only for illustration and not specifically limited. In practical applications, the amounts of Li2S, P2S5, and ZnCl2 should be comprehensively considered and optimized according to factors such as the target performance of the electrolyte, the specific requirements of the application scenario, and production costs. It is necessary to ensure both the high ionic conductivity and interfacial stability of the electrolyte and the mechanical strength and chemical stability of the material.

[0048] By preliminarily mixing Li2S, P2S5, and ZnCl2, the uniform distribution of each component is ensured, which helps to achieve more consistent amorphization and densification during the subsequent ball milling and sintering processes, thereby improving the ionic conductivity of the electrolyte.

[0049] S102: Perform amorphization treatment on the mixed powder to obtain a solid electrolyte powder precursor.

[0050] In this step, amorphization treatment refers to the process of transforming the mixed powder into an amorphous structure. Usually, mechanical means such as a high-energy ball mill are used to apply mechanical energy to the mixed powder, causing changes in its crystal structure, thereby forming an amorphous or non-crystalline material.

[0051] In a possible implementation, place the mixed powder in a ball milling jar and use a ball mill for ball milling treatment to obtain a solid electrolyte powder precursor. The ball milling speed during ball milling treatment is 100 - 800 rpm, and the ball milling time is 10 - 50 h. Preferably, the ball milling speed during ball milling treatment is 500 - 800 rpm, and the ball milling time is 30 - 40 h.

[0052] Li2S, P2S5, and ZnCl2 in the mixed powder obtain a solid electrolyte powder precursor through continuous mechanical impact and friction in the ball milling jar. The ball milling treatment destroys the original ordered crystal structure, thereby forming an amorphous state. The ball milling speed and ball milling time during ball milling treatment ensure sufficient energy input from the ball mill, enabling the material to be fully amorphized and uniformly mixed.

[0053] Specifically, preferably, the ball milling speed can be 500 rpm, 600 rpm, 700 rpm or 800 rpm; the ball milling time can be 30 h, 32 h, 35 h, 37 h or 40 h. The high speed of the ball milling treatment provides a stronger mechanical impact force, accelerating the destruction of the crystal lattice and the mixing of materials. The moderate ball milling time ensures the sufficiency of this process and avoids over-fine particles or material degradation caused by over-ball milling. The solid electrolyte powder precursor obtained after ball milling the mixed powder obtained in S101 is amorphous, with a larger free volume and a shorter ion migration path. Therefore, it is more conducive to the rapid migration of lithium ions and helps to improve the lithium ion conductivity of the electrolyte. In addition, the amorphization treatment can also promote the chemical reaction between the components, making ZnCl2 more uniformly doped into the sulfide matrix and further enhancing the interfacial stability and chemical stability of the electrolyte.

[0054] S103: Sinter the solid electrolyte powder precursor at high temperature under an inert gas to obtain a sulfide solid electrolyte.

[0055] In this step, the high-temperature sintering process is a process of bonding and densification between the solid electrolyte powder precursors by heating, thereby improving the mechanical strength and electrochemical performance of the electrolyte. The inert gas can effectively prevent the solid electrolyte powder precursor from undergoing unnecessary chemical reactions with oxygen or moisture in the environment under high-temperature conditions, thereby maintaining the purity and stability of the material. Commonly used inert gases include argon (Ar), nitrogen (N2), etc.

[0056] In a possible implementation manner, when performing high-temperature sintering, the high-temperature sintering temperature is 200 - 400 °C, and the high-temperature sintering time is 5 - 10 h.

[0057] During the sintering process, the solid electrolyte powder precursor is placed in a sintering furnace and gradually heated to the required high temperature to obtain a sulfide solid electrolyte. Too low a temperature may result in insufficient sintering, with insufficient densification and mechanical strength of the electrolyte; while too high a temperature may cause over-crystallization or decomposition of the material, affecting the conductivity and stability of the electrolyte. Exemplarily, the high-temperature sintering temperature can be 200 °C, 300 °C, 400 °C or 500 °C, etc., and the high-temperature sintering time can be 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, etc. Here, it is only for example, and the specific temperature values and times are not limited. In actual applications, the specific temperature and time of high-temperature sintering need to be optimized and adjusted according to the composition of the material, the target performance, and the specific requirements of the application scenario.

[0058] Sinter the solid electrolyte powder precursor at high temperature under an inert gas to obtain a sulfide solid electrolyte. In a possible implementation manner, the molecular formula of the sulfide solid electrolyte is Li 3+x P1-x Zn x S 4-2x Cl 2x , wherein the value range of x is 0 < x < 0.1. Preferably, the value range of x is 0.01 ≤ x ≤ 0.08.

[0059] It should be noted that the molecular formula of the sulfide solid electrolyte is Li 3+x P 1-x Zn x S 4-2x Cl 2x . In this formula, the value of x cannot be too small, otherwise the ionic conductivity cannot be effectively improved; the value of x cannot be too large either, otherwise the doping amount is too much, which will cause ZnCl2 to be unable to effectively dope Li3PS4, thereby affecting the electrochemical performance of the sulfide electrolyte.

[0060] By high-temperature sintering of the solid electrolyte powder precursor under an inert gas, bonding and densification occur between the powder particles, forming a sulfide solid electrolyte Li 3+x P 1-x Zn x S 4-2x Cl 2x , significantly improving the mechanical strength, ionic conductivity and electrochemical stability of the sulfide solid electrolyte.

[0061] The preparation method of the sulfide solid electrolyte provided by the embodiment of the present application includes preliminarily mixing Li2S, P2S5, and ZnCl2 in a specific molar ratio to obtain a mixed powder; then performing an amorphization treatment on the mixed powder to obtain a solid electrolyte powder precursor; finally, placing the solid electrolyte powder precursor in an inert gas environment for high-temperature sintering to obtain a sulfide solid electrolyte Li 3+x P 1-x Zn x S 4-2x Cl 2x . By the above method, the prepared sulfide solid electrolyte has high mechanical strength, ionic conductivity and electrochemical stability, further improving the overall performance and reliability of the battery.

[0062] The present application also provides an electrolyte, including the sulfide solid electrolyte prepared by the method described in Figure 1 the embodiment.

[0063] The present application also provides a solid-state battery, including a positive electrode, a negative electrode, and the electrolyte described in the previous embodiment.

[0064] The present application also provides an electrical device, including a device main body and the solid-state battery described in the previous embodiment.

[0065] Exemplarily, the solid-state battery can be used as a power battery for a vehicle to provide a power source for the vehicle. In addition, the solid-state battery is also applicable to the battery fields of computers, communications, and consumer electronics (3C), providing stable and long-lasting power support for them.

[0066] The following will specifically introduce the preparation method of the sulfide solid electrolyte and the application of the solid-state battery provided by this application through specific embodiments.

[0067] Unless otherwise specified, the reagents, materials, and instruments used in the following embodiments are all conventional reagents, conventional materials, and conventional instruments in this field, which can all be obtained through commercial purchase, and the reagents involved can also be obtained through conventional methods in this field.

[0068] In the following examples and comparative examples, the test method for ionic conductivity is as follows: Weigh 100 mg of electrolyte powder and place it in a mold, and press and form it under a pressure of 300 MPa. Under the state of applying pressure, use an electrochemical workstation and adopt the electrochemical impedance measurement method to measure the impedance value of the electrolyte material at room temperature of 25 °C. Take the real value of the impedance at the measurement point with the absolute minimum of the phases of multiple impedances as the impedance value of the electrolyte material. Using this impedance value, calculate the ionic conductivity.

[0069] The test method for the lithium stability of the solid-state battery is as follows: Weigh 100 mg of electrolyte powder and place it in a mold, and press and form it under a pressure of 300 MPa. Then place lithium sheets on both sides of the electrolyte sheet to form a symmetric battery (test conditions: 0.1 mA / cm 2 constant current test), record the cycle time of the battery under this constant current condition, and evaluate the interfacial stability between the electrolyte and lithium metal.

[0070] Example 1

[0071] This example provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method includes the following steps:

[0072] (1) Place Li2S, P2S5, and ZnCl2 in a large-scale pulverizer according to a molar ratio of 3.01:0.99:0.02, and perform preliminary mixing treatment for 10 min to obtain a mixed powder;

[0073] (2) Add the mixed powder into a ball milling jar for amorphization treatment. Use a ball mill to mill at a speed of 500 rpm for 30 h to obtain a precursor of the solid electrolyte powder.

[0074] (3) Sinter the precursor of the solid electrolyte powder in an inert gas at 300 °C for 10 h to obtain a sulfide solid electrolyte with the molecular formula Li 3.01 P 0.99 Zn 0.01 S 3.98 Cl 0.02 .

[0075] Example 2

[0076] This example provides a sulfide solid electrolyte with the molecular formula Li 3+x P 1- x Zn x S 4-2x Cl 2x . Its preparation method is basically the same as that of Example 1, except that in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder mixer according to a molar ratio of 3.05:0.95:0.1, and preliminarily mixed for 10 min to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.05 P 0.95 Zn 0.05 S 3.9 Cl 0.1 is obtained.

[0077] Example 3

[0078] This example provides a sulfide solid electrolyte with the molecular formula Li 3+x P 1- x Zn x S 4-2x Cl 2x . Its preparation method is basically the same as that of Example 1, except that in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder mixer according to a molar ratio of 3.08:0.92:0.16, and preliminarily mixed for 10 min to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.08 P 0.92 Zn 0.08 S 3.84 Cl 0.16 is obtained.

[0079] Example 4

[0080] This embodiment provides a sulfide solid electrolyte. The molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (3): the solid electrolyte powder precursor is sintered in an inert gas at 400 °C for 5 h. Finally, a sulfide solid electrolyte with the molecular formula Li 3.01 P 0.99 Zn 0.01 S 3.98 Cl 0.02 is obtained.

[0081] Example 5

[0082] This embodiment provides a sulfide solid electrolyte. The molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (3): the solid electrolyte powder precursor is sintered in an inert gas at 300 °C for 5 h. Finally, a sulfide solid electrolyte with the molecular formula Li 3.01 P 0.99 Zn 0.01 S 3.98 Cl 0.02 is obtained.

[0083] Example 6

[0084] This embodiment provides a sulfide solid electrolyte. The molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (1): Li2S, P2S5, and ZnCl2 are placed in a large-scale powder mixer according to a molar ratio of 3.03:0.97:0.06, and preliminarily mixed for 10 min to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.03 P 0.97 Zn 0.03 S 3.94 Cl 0.06 is obtained.

[0085] Example 7

[0086] This embodiment provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder mixer according to a molar ratio of 3.04:0.96:0.08, and preliminarily mixed for 10 minutes to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.04 P 0.96 Zn 0.04 S 3.92 Cl 0.08 is obtained.

[0087] Example 8

[0088] This embodiment provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder mixer according to a molar ratio of 3.03:0.97:0.06, and preliminarily mixed for 10 minutes to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.03 P 0.97 Zn 0.03 S 3.94 Cl 0.06 is obtained.

[0089] Example 9

[0090] This embodiment provides a sulfide solid electrolyte, and the molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that: in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder mixer according to a molar ratio of 3.06:0.94:0.12, and preliminarily mixed for 10 minutes to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.06 P 0.94 Zn 0.06 S 3.88Cl 0.12 sulfide solid electrolyte

[0091] Example 10

[0092] This example provides a sulfide solid electrolyte. The molecular formula of the sulfide solid electrolyte is Li 3+x P 1- x Zn x S 4-2x Cl 2x , and its preparation method is basically the same as that of Example 1, except that in step (1): Li2S, P2S5, and ZnCl2 are placed in a Dade powder grinder according to a molar ratio of 3.07:0.93:0.14, and preliminarily mixed for 10 min to obtain a mixed powder. Finally, a sulfide solid electrolyte with the molecular formula Li 3.07 P 0.93 Zn 0.07 S 3.86 Cl 0.14 is obtained

[0093] Comparative Example 1

[0094] This example provides a sulfide solid electrolyte. Its preparation method is basically the same as that of Example 1, except that ZnCl2 is not used for element doping treatment of the sulfide solid electrolyte. Its preparation method includes the following steps:

[0095] (1) Li2S and P2S5 are placed in a Dade powder grinder according to a molar ratio of 3:1, and preliminarily mixed for 10 min to obtain a mixed powder;

[0096] (2) The mixed powder is added to a ball milling tank for amorphization treatment, and ball milled at a speed of 500 rpm for 30 h by a ball mill to obtain a precursor of the solid electrolyte powder;

[0097] (3) The precursor of the solid electrolyte powder is sintered in an inert gas at 300 °C for 10 h to obtain a sulfide solid electrolyte with the molecular formula Li3PS4.

[0098] Test Example

[0099] The following performance tests are carried out on the sulfide solid electrolytes of the above examples and comparative examples:

[0100] (1)The test method for ionic conductivity is as follows: Weigh 100 mg of the electrolyte powder and place it in a mold, then press and form it under a pressure of 300 MPa. Under the state of applied pressure, use an electrochemical workstation and adopt the electrochemical impedance measurement method to measure the impedance value of the electrolyte material at room temperature of 25 °C. Take the real value of the impedance at the measurement point with the absolute minimum of the phases of multiple impedances as the impedance value of the electrolyte material. Calculate the ionic conductivity using this impedance value. The test results of the ionic conductivity are shown in Table 1.

[0101] (2)The test method for the lithium stability of the solid-state battery is as follows: Weigh 100 mg of the electrolyte powder and place it in a mold, then press and form it under a pressure of 300 MPa. Then place lithium sheets on both sides of the electrolyte sheet to form a symmetric battery (test condition: 0.1 mA / cm 2 constant current test), record the cycle time of the battery under this constant current condition to evaluate the interfacial stability between the electrolyte and lithium metal. The test results of the lithium stability of the solid-state battery are shown in Table 2.

[0102] Table 1 Test Results of Ionic Conductivity

[0103]

[0104] The following conclusions can be analyzed from Table 1:

[0105] Comparing Examples 1-10 with Comparative Example 1, it can be seen that by doping Li3PS4 with ZnCl2, the ionic conductivity of the solid electrolyte can be effectively improved. This is because by doping zinc elements, the activation energy required for lithium ions to migrate in the solid sulfide electrolyte can be reduced, enabling lithium ions to achieve rapid migration at a lower energy state, improving the ionic conduction performance of the electrolyte, and further enhancing the charge-discharge efficiency of the battery.

[0106] Correspondingly, in Comparative Example 1, the ionic conductivity of Li3PS4 without ZnCl2 doping is only 0.73 mS / cm, which is significantly lower than the ionic conductivity of the solid sulfide electrolyte in Examples 1-10, further verifying the positive effect of the doping of Zn and Cl on improving the ionic conductivity.

[0107] Table 2 Test Results of the Lithium Stability of the Solid-State Battery

[0108]

[0109] The length of the cycle time reflects the chemical stability and electrochemical compatibility of the electrolyte when in contact with lithium metal. A longer cycle time usually indicates that the electrolyte has better lithium stability and can effectively inhibit the growth of lithium dendrites and the increase of interfacial impedance.

[0110] The following conclusions can be analyzed from Table 2:

[0111] As can be seen from Examples 1-10 compared with Comparative Example 1, by doping Li3PS4 with ZnCl2, the cycle time of the battery is higher than that when the solid sulfide electrolyte in Comparative Example 1 is in contact with the battery. It shows that doping the halide element into Li3PS4 can effectively improve the interfacial stability between the sulfide electrolyte and lithium metal.

[0112] Correspondingly, in Comparative Example 1, the cycle time of the battery when the undoped ZnCl2 Li3PS4 is in contact with the battery is only 240 hours, which is significantly lower than the cycle time of the battery when the solid sulfide electrolytes in Examples 1-10 are in contact with the battery, further verifying the positive effect of Zn and Cl doping on improving the cycle stability. The reason analysis is as follows:

[0113] When the solid-state battery works, the solid sulfide electrolyte reacts with the surface of metallic lithium, and an interfacial layer containing components such as lithium chloride (LiCl) and lithium sulfide (Li2S) is formed at the interface.

[0114] On the one hand, the interfacial layer has good chemical stability and ionic conductivity, which can serve as a bridge for lithium-ion transport, while preventing the direct contact between lithium metal and the sulfide electrolyte and avoiding harmful side reactions between the two, thereby improving the interfacial stability between the sulfide electrolyte and lithium metal. On the other hand, the formed LiCl can reduce the activity of some active sites in the sulfide electrolyte that are prone to react with lithium metal, reduce the chemical reactions at the interface, and maintain the interfacial stability.

[0115] At the same time, LiCl can provide an additional lithium-ion transport path at the interface, form a specific coordination structure with the ions in the sulfide electrolyte, and guide the lithium ions to migrate along the channels formed by the coordination structure, making the transport of lithium ions between the lithium metal and the sulfide electrolyte interface more orderly and efficient, reducing the obstacles and chaos in the ion transport process, lowering the interfacial resistance, and further stabilizing the interface.

[0116] During the charge and discharge process of the solid-state battery, LiCl helps to homogenize the lithium-ion flux at the interface, helps to regulate the deposition and extraction rates of lithium ions at different positions of the interface, avoids the excessive deposition or extraction of lithium ions in local areas, prevents problems such as lithium dendrite growth or interface damage at the interface, and keeps the interface stable.

[0117] In addition, the introduction of zinc element also enhances the chemical stability between the solid sulfide electrolyte and the electrode material. Zinc doping can change the chemical properties and structure of the electrolyte, making it more chemically inert at the interface, reducing the direct chemical reaction between the electrolyte and the electrode material, and reducing the generation of by-products, thereby improving the overall stability of the material.

[0118] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that, The method includes: Pre - mixing Li2S, P2S5, and ZnCl2 to obtain a mixed powder; Performing an amorphization treatment on the mixed powder to obtain a precursor of a solid electrolyte powder; Performing high - temperature sintering on the precursor of the solid electrolyte powder under an inert gas to obtain a sulfide solid electrolyte.

2. The method according to claim 1, characterized in that, The molecular formula of the sulfide solid electrolyte is Li 3+ x P 1-x Zn x S 4-2x Cl 2x , where the value range of x is 0 < x < 0.

1.

3. The method according to claim 2, characterized in that, The value range of x is 0.01 ≦ x ≦ 0.

08.

4. The method according to any one of claims 1 to 3, characterized in that, Before the step of pre - mixing Li2S, P2S5, and ZnCl2 to obtain a mixed powder, the method further includes: Weighing Li2S, P2S5, and ZnCl2 according to the molar ratio of Li2S:P2S5:ZnCl2 being (3.01 - 3.08):(0.92 - 0.99):(0.02 - 0.16).

5. The method according to any one of claims 1 to 3, characterized in that, The pre - mixing method includes dry mixing or wet mixing.

6. The method according to claim 5, wherein The pre - mixing method is mechanical mixing in dry mixing.

7. The method according to any one of claims 1 to 3, characterized in that, The step of performing an amorphization treatment on the mixed powder to obtain a precursor of a solid electrolyte powder includes: Placing the mixed powder in a ball - milling tank and performing ball - milling treatment with a ball mill to obtain the precursor of the solid electrolyte powder.

8. The method according to claim 7, wherein When performing the ball - milling treatment, the ball - milling speed is 100 - 800 rpm and the ball - milling time is 10 - 50 h.

9. The method according to claim 8, wherein When performing the ball - milling treatment, the ball - milling speed is 500 - 800 rpm and the ball - milling time is 30 - 40 h.

10. The method according to any one of claims 1 to 3, characterized in that When performing high - temperature sintering, the high - temperature sintering temperature is 200 - 400 °C and the high - temperature sintering time is 5 - 10 h.

11. The method according to any one of claims 1 to 3, characterized in that, The value range of the average particle size D50 of the Li2S is 3 ≤ D50 ≤ 50 .

12. The method according to claim 11, wherein The value range of the average particle size D50 of the Li2S is 3 ≤ D50 ≤ 10 .

13. An electrolyte, characterized in that, It includes a sulfide solid electrolyte prepared by the method according to any one of claims 1 to 12.

14. A solid-state battery, characterized in that, It includes: A positive electrode, a negative electrode, and the electrolyte according to claim 13.

15. An electrical device, characterized in that, It includes: A device main body and the solid - state battery according to claim 14.

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