Solid-state battery and preparation method thereof

Abstract

The invention provides a solid-state battery and a preparation method thereof. The method comprises the following steps: carrying out preliminary mixing on Li2S, P2S5, LiCl and LiAlO2 which are weighed according to the stoichiometric ratio of the chemical general formula Li < 6 + 2x > Al < x > P < 1-x > S < 5-2x > O < 2x > Cl to obtain mixed powder; carrying out non-crystallization treatment on the mixed powder to obtain a solid electrolyte powder precursor; carrying out high-temperature sintering treatment on the solid electrolyte powder precursor in an inert atmosphere to obtain a sulfide solid electrolyte; carrying out refining treatment on the sulfide solid electrolyte, mixing the refined sulfide solid electrolyte with a binder, and pressurizing to prepare an electrolyte layer; and assembling the positive plate, the electrolyte layer and the lithium metal negative plate to obtain the solid-state battery. The sulfide solid electrolyte in the solid-state battery prepared by the method is doped with the element O and the element Al, so that the air stability and the lithium metal interface stability of the sulfide solid electrolyte are improved, and various electrochemical properties of the solid-state battery are further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a solid-state battery and a preparation method thereof. BACKGROUND

[0002] With the proposal of the double carbon policy, it is urgent to develop high-energy density and long-life energy storage systems. Rechargeable battery systems are the most viable devices for storing electricity generated by various intermittent and renewable energy sources such as solar and wind energy.

[0003] In recent years, all-solid-state lithium batteries using solid-state electrolytes instead of traditional liquid electrolytes have attracted much attention due to their high energy density and good safety performance. Among them, sulfide solid-state electrolytes have higher ionic conductivity and good mechanical ductility, and have more significant application potential.

[0004] However, in the practical application of sulfide solid-state electrolytes, there are still challenges such as poor chemical stability, narrow electrochemical stability window, poor electrolyte / electrode interface compatibility, etc., which greatly limit the further development of sulfide solid-state electrolytes. Among them, sulfide solid-state electrolytes with a thioargentite (Li6PS5Cl) structure have high ionic conduction capacity, but their air stability and lithium metal interface stability still need to be improved, which limits their large-scale application. Therefore, how to improve the air stability and lithium metal interface stability of Li6PS5Cl applied in solid-state batteries is a hot research topic. SUMMARY

[0005] The present application provides a solid-state battery and a preparation method thereof, to achieve the effect of improving the air stability and lithium metal interface stability of sulfide solid-state electrolytes, and optimizing the ionic conductivity and cycle performance of solid-state batteries and other electrochemical properties.

[0006] In a first aspect of the present application, a preparation method of a solid-state battery is provided, which comprises:

[0007] Li 6+2x Al x P 1-x S 5-2x O 2x The stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 according to the chemical formula Li

[0008] The mixed powder is subjected to amorphous treatment to obtain a solid-state electrolyte powder precursor;

[0009] The solid-state electrolyte powder precursor is subjected to high-temperature sintering treatment in an inert atmosphere to obtain the sulfide solid-state electrolyte;

[0010] After the sulfide solid electrolyte is refined, the refined sulfide solid electrolyte is mixed with a binder and is pressed to form an electrolyte layer;

[0011] The positive electrode sheet, the electrolyte layer, and a lithium metal negative electrode sheet are assembled to obtain the solid-state battery.

[0012] According to an embodiment of the present application, 0.03≤x≤0.06.

[0013] According to an embodiment of the present application, the average particle size D 50 of the Li2S is 3-50 μm.

[0014] According to an embodiment of the present application, the average particle size D 50 of the Li2S is 3-10 μm.

[0015] According to an embodiment of the present application, the amorphization treatment on the mixed powder to obtain a solid electrolyte powder precursor comprises:

[0016] The mixed powder is placed in a ball mill tank and is subjected to ball milling treatment by a ball mill to obtain the solid electrolyte powder precursor.

[0017] According to an embodiment of the present application, the ball milling speed of the ball milling treatment is 100-800 rpm; and / or, the ball milling time of the ball milling treatment is 10-50 h.

[0018] According to an embodiment of the present application, the ball milling speed of the ball milling treatment is 500-800 rpm; and / or, the ball milling time of the ball milling treatment is 30-40 h.

[0019] According to an embodiment of the present application, the temperature of the high-temperature sintering treatment is 500-600 °C;

[0020] According to an embodiment of the present application, the time of the high-temperature sintering treatment is 5-10 h.

[0021] In a second aspect of the present application, a solid-state battery is provided, which is prepared by the method of the first aspect.

[0022] In a third aspect of the present application, an electric device is provided, which comprises an electric device body and the solid-state battery of the first aspect.

[0023] In the implementation of the present application, at least the following beneficial effects are achieved:

[0024] The solid-state electrolyte prepared by the method provided by the present application is a sulfide solid-state electrolyte, wherein the S element in the Li6PS5Cl type sulfide solid-state electrolyte is partially replaced by the O element, and the P element in the Li6PS5Cl type sulfide solid-state electrolyte is partially replaced by the Al element. On the one hand, the PS4 3- group in the sulfide solid-state electrolyte is adjusted to be POS3 3- group, which can improve the air stability of the sulfide solid-state electrolyte, and on the other hand, the introduction of the Al element in the electrolyte can react with the lithium metal negative electrode to generate Li3Al, which can reduce the side reaction between the sulfide solid-state electrolyte and the lithium metal negative electrode, and further reduce the content of the impurities Li2S and Li3P generated by the side reaction. + The Li-Al alloy with high ion conductivity generated by the reaction between the O element and the lithium metal negative electrode can be uniformly deposited at the interface, and the introduction of the O element in the electrolyte can generate Li2O with high ion conductivity, so as to improve the ion conductivity of the sulfide solid-state electrolyte on the basis of reducing the interface stability of the sulfide solid-state electrolyte to the lithium metal. Further, the sulfide solid-state electrolyte with optimized air stability, interface stability to the lithium metal, and ion conductivity is applied to the solid-state battery provided by the present application, which can effectively improve the electrochemical performance of the solid-state battery provided by the present application, including but not limited to the cycle performance and ion conductivity. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application.

[0026] Figure 1 The flowchart of the preparation method of the sulfide solid-state electrolyte provided by the first embodiment of the present application is shown.

[0027] The specific embodiments of the present application have been shown in the above drawings, and will be described in more detail hereinafter. These drawings and the written description are not intended to limit the scope of the inventive concept in any way, but to illustrate the inventive concept to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to better understand the scheme of the present application, the present application will be further described in detail below. The specific embodiments listed below are only used to describe the principles and characteristics of the present application, and the examples are used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] To facilitate the understanding of the technical content of the present scheme, the background art is introduced in detail as follows:

[0030] Firstly, sulfide solid electrolytes of argyrodite (Li6PS5Cl) structure, although have high lithium ion conductivity (10 -3 ~10 -2 S / cm), but according to the hard-soft acid-base theory, the PS4 3− group in the sulfide solid electrolyte is easy to react with H2O in the air, resulting in poor air stability of the sulfide solid. However, the poor air stability leads to the sulfide solid electrolyte to react with H2O after being exposed to air, releasing toxic H2S gas, and also damaging the intrinsic structure of the electrolyte, affecting the application of the sulfide solid electrolyte in the battery.

[0031] In addition, metal lithium has been considered as the most ideal negative electrode material for the next generation of high specific energy and rechargeable batteries due to its high specific capacity (3861mAh / g), low electrochemical potential and small density (0.534g / cm 3 ), but the problems such as lithium dendrite growth of lithium metal seriously limit its practical application. Specifically, in the solid-state battery with lithium metal as the negative electrode, chemical reaction easily occurs between the sulfide solid electrolyte and the surface of lithium metal, forming a solid electrolyte interface film (SEI) composed of multiple products at the interface, among which Li2S and Li3P generated by the reaction will have a significant negative impact on the performance of the battery: Li2S has electronic insulating property, which will seriously hinder the transmission of lithium ions, resulting in a significant increase in interface impedance and reducing the ion conduction efficiency of the battery; while Li3P has electronic conductivity, which will become an electrically conductive bridge for lithium dendrite growth, accelerating the growth of lithium dendrites, not only causing rapid capacity decay of the battery, but also possibly puncturing the electrolyte layer to cause short circuit risk, affecting the cycle stability and safety of the battery.

[0032] Based on the above background art, the inventors found during research that O element and Al element can be considered for doping the original Li6PS5Cl type sulfide solid electrolyte, and at least two technical effects can be achieved by partially replacing S element with O element and P element with Al element:

[0033] On the one hand, the doping of O element can realize the regulation of PS4 3- group in the structure of sulfide solid electrolyte to obtain POS3 3- functional group, and PS4 3-The reduction of the groups can effectively inhibit the reaction between the sulfide solid-state electrolyte and water, thereby achieving the effect of significantly improving the air stability of the sulfide solid-state electrolyte. Further, the high air stability of the sulfide solid-state electrolyte can ensure that the key performance of the sulfide solid-state electrolyte, such as ionic conductivity, is not damaged during the preparation of the solid-state battery, thereby achieving the effect of optimizing the ionic conductivity and storage life of the solid-state battery.

[0034] On the other hand, the reduction of the content of S atoms and P atoms in the sulfide solid-state electrolyte can weaken the side reaction between the sulfide solid-state electrolyte and the metal lithium interface in the solid-state battery with lithium metal as the negative electrode, thereby reducing the content of impurities Li2S and impurities Li3P, and further reducing the negative effects of impurities Li2S and impurities Li3P on the performance of the battery. On this basis, the doping of O elements and Al elements can also form an SEI layer containing Li2O and Li-Al alloy between the sulfide solid-state electrolyte and the metal lithium interface, wherein Li2O has high ionic conductivity and can ensure the ion transmission at the interface; the Li-Al alloy has a strong affinity for lithium and can uniformly deposit at the interface, thereby inhibiting the growth of lithium dendrites. + During the transmission process, the Li + uniformly deposit at the interface, thereby inhibiting the growth of lithium dendrites. Therefore, the present application can achieve the effect of significantly improving the stability of the sulfide solid-state electrolyte to the lithium metal interface. Further, the high stability of the sulfide solid-state electrolyte to the lithium metal interface can reduce the interface impedance of the solid-state battery, improve the ionic conductivity, inhibit lithium dendrites, and achieve the effect of effectively improving the electrochemical performance such as the cycle performance and ionic conductivity of the solid-state battery.

[0035] Therefore, the present application is proposed to improve the air stability and the stability to the lithium metal interface of the sulfide solid-state electrolyte, thereby achieving the effect of optimizing the ionic conductivity and the cycle performance of the solid-state battery.

[0036] The technical solutions of the present application and how the present application solves the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes may not be described again in some examples. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0037] Embodiment one of the present application provides a preparation method of the above-mentioned sulfide solid-state electrolyte, Figure 1 The flowchart of the preparation method of the sulfide solid-state electrolyte provided in embodiment one of the present application is shown in Figure 1 The preparation method provided in the present embodiment includes:

[0038] S101. Preliminarily mix Li2S, P2S5, LiCl and LiAlO2 weighed in a stoichiometric ratio according to a general chemical formula to obtain a mixed powder.

[0039] Among them, the chemical formula is Li 6+2x Al x P 1-x S 5-2x O 2x Cl, 0.01≤x≤0.08.

[0040] Specifically, Li2S, P2S5, and LiCl are commonly used materials for preparing sulfide solid electrolytes; LiAlO2 is used as a dopant to dope Al and O elements in conventional sulfide solid electrolytes.

[0041] In this step, first according to the chemical formula Li 6+2x Al x P 1-x S 5-2x O 2x Appropriate amounts of Li2S, P2S5, LiCl, and LiAlO2 are weighed in a stoichiometric ratio of 1,2-dimethyl-1,4-dioxane. The weighed Li2S, P2S5, LiCl, and LiAlO2 are then preliminarily mixed. It should be understood that the purpose of preliminarily mixing is to pre-disperse the raw material powders, which facilitates uniformity in the subsequent amorphization process.

[0042] For example, if x is selected as 0.02, Li2S, P2S5, LiCl and LiAlO2 are weighed according to the stoichiometric ratio of 2.51:0.49:1:0.02 to prepare Li 6.04 Al 0.02 P 0.98 S 4.96 O 0.04 This is just an example and is not a specific limitation. In actual applications, the selection of x should be comprehensively considered and optimized based on factors such as the target performance of the electrolyte, the specific requirements of the application scenario, and production costs.

[0043] It should be understood that the value of x cannot be too small, otherwise the air stability will not be effectively improved; at the same time, the value of x cannot be too large, otherwise excessive addition of dopants will cause some dopants to be unable to be doped and will exist in the sulfide solid electrolyte in the form of impurities, thereby affecting the ionic conductivity of the sulfide solid electrolyte.

[0044] Preferably, 0.03≤x≤0.06. Selecting x within this range will ensure that the subsequently prepared doped sulfide solid electrolyte has both excellent air stability and lithium metal interface stability.

[0045] It should be noted that the Li2S used in the present application can be self-made or purchased. In addition, the present application does not specifically limit the average particle size D 50 , shape and purity of Li2S. Specifically, the shape of Li2S can be spherical, polygonal, irregular and the like; from the perspective of preparing high-purity sulfide solid electrolyte, the higher the purity of Li2S, the better.

[0046] In one possible implementation, the average particle size D 50 of Li2S is 3-50 μm. Preferably, the average particle size D 50 of Li2S is 3-10 μm.

[0047] Specifically, the average particle size D 50 of Li2S used in the present application is, for example, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or a new range formed by selecting any two of the foregoing values, and the value taken in the new range. It should be understood that Li2S with an average particle size D 50 of 3 μm to 50 μm, especially 3 μm to 10 μm, has a higher dispersion effect and specific surface area due to the smaller particle size, which is beneficial to promoting the uniformity of raw material mixing, the sufficiency of subsequent high-temperature sintering reaction, and thus improving the ion conductivity and other properties of the prepared sulfide solid electrolyte.

[0048] In one possible implementation, the preliminary mixing method includes dry mixing or wet mixing, and preferably, the preliminary mixing method is mechanical mixing in dry mixing.

[0049] Dry mixing refers to a method of mixing solid materials with each other by mechanical force or air flow without adding liquid medium, which has the characteristics of simple operation, no need for subsequent drying steps, and low energy consumption. Mechanical mixing is a typical dry mixing method, which mainly relies on the movement of mechanical devices to make the materials move relatively, thereby achieving mixing, such as stirring mixing, grinding mixing, vibration mixing, etc.

[0050] Wet mixing is a method of mixing materials with liquid medium (such as solvent, water, etc.), and dispersing and uniformly mixing the materials in the liquid phase by stirring, grinding, etc. This method usually needs subsequent evaporation, drying and other steps to remove the liquid medium.

[0051] S102, performing amorphous treatment on the mixed powder to obtain a solid electrolyte powder precursor.

[0052] The amorphization treatment refers to a process of changing the arrangement of atoms or molecules of the mixed powder from an ordered crystal structure to an amorphous non-crystal structure.

[0053] In this step, mechanical energy can be applied to the mixed powder by mechanical treatment to convert its crystal structure into a non-crystal structure, thereby obtaining a solid-state electrolyte powder precursor. It should be understood that the solid-state electrolyte powder precursor obtained after amorphization treatment is in an amorphous state, has a larger ion conduction path and a lower migration activation energy, which is beneficial 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 during the subsequent high-temperature sintering process, so that LiAlO2 is more uniformly doped into the sulfide matrix, further enhancing the air stability and lithium metal interface stability of the electrolyte.

[0054] In one possible implementation, the mixed powder is placed in a ball mill tank and subjected to ball milling treatment by a ball mill to obtain the solid-state electrolyte powder precursor.

[0055] Optionally, the ball milling speed of the ball milling treatment is 100-800 rpm; and / or, the ball milling time of the ball milling treatment is 10-50 h. Preferably, the ball milling speed of the ball milling treatment is 500-800 rpm; and / or, the ball milling time of the ball milling treatment is 30-40 h.

[0056] It should be understood that the mixed powder is subjected to continuous mechanical impact and friction in the ball mill tank, so that the original ordered crystal structure is destroyed to form an amorphous state. In addition, the ball milling speed and the ball milling time during the ball milling treatment ensure sufficient energy input of the ball mill to fully amorphize and uniformly mix the material.

[0057] Specifically, the ball milling speed is, for example, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, or a new range formed by selecting any two of the foregoing values, and the values taken within the new range; and / or, the ball milling time is, for example, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 50 h, or a new range formed by selecting any two of the foregoing values, and the values taken within the new range. It should be understood that the ball milling speed cannot be too high, otherwise the material will be excessively broken or local high temperature will be generated due to violent collision to cause side reactions; the ball milling speed also cannot be too low, otherwise the lower kinetic energy of the grinding balls will be difficult to break the crystal structure of the raw material and cannot achieve complete amorphization. In addition, the appropriate ball milling time is also a key to fully amorphize the raw material.

[0058] S103, performing high-temperature sintering treatment on the solid electrolyte powder precursor in an inert atmosphere to obtain a sulfide solid electrolyte.

[0059] In this step, the purpose of high-temperature sintering treatment is to make the substances in the solid electrolyte powder precursor react at high temperature to generate a sulfide solid electrolyte.

[0060] The high-temperature sintering in an inert atmosphere can effectively prevent the sulfide solid electrolyte from reacting with oxygen or moisture in the environment at high temperature, thereby ensuring the purity and stability of the material. The commonly used inert atmosphere is at least one of nitrogen, argon, helium, and neon.

[0061] In one possible implementation, the temperature of the high-temperature sintering treatment is 500-600°C; and / or, the time of the high-temperature sintering treatment is 5-10h.

[0062] It should be understood that too low a temperature or too short a time can result in insufficient reaction between the substances, affecting the ion conductivity and other properties of the obtained sulfide solid electrolyte, and too high a temperature or too long a time can cause side reactions between the substances, thereby producing impurities in the sulfide solid electrolyte. Therefore, appropriate temperature and time are key to the sulfide solid electrolyte. Specifically, the temperature of the high-temperature sintering treatment is, for example, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, or a value selected from any two of the foregoing to form a new range, and a value taken within the new range; and / or, the time of the high-temperature sintering treatment is, for example, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, or a value selected from any two of the foregoing to form a new range, and a value taken within the new range.

[0063] S104, after performing the refinement treatment on the sulfide solid electrolyte, mixing the refined sulfide solid electrolyte with a binder and pressing to form an electrolyte layer.

[0064] In this step, in order to improve the density of the electrolyte layer and the ion conductivity of the battery, the sulfide solid electrolyte prepared in the above step needs to be refined to obtain a refined sulfide solid electrolyte; then, in order to ensure that the refined sulfide electrolyte can be formed and that the electrolyte layer formed has certain mechanical stability, the refined sulfide solid electrolyte needs to be mixed with a binder, and the mixture needs to be pressed to form an electrolyte layer.

[0065] The binder should be selected from at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE) and polyacrylic acid (PAA) which do not react with the sulfide electrolyte, do not hinder the conduction of lithium ions, have good adhesion and chemical stability.

[0066] S105, the positive electrode sheet, the electrolyte layer and the lithium metal negative electrode sheet are assembled to obtain the solid-state battery.

[0067] In this step, the positive electrode sheet, the electrolyte layer and the lithium metal negative electrode are sequentially stacked and then assembled under pressure to obtain the solid-state battery.

[0068] In practical applications, the positive electrode sheet specifically includes a positive electrode current collector and a positive electrode active layer formed by a positive electrode active material arranged on the surface of the positive electrode current collector; it should be understood that the present application does not strictly limit the positive electrode active material and the positive electrode current collector in the positive electrode sheet, wherein the positive electrode current collector can be at least one of aluminum foil and nickel foil; the positive electrode active material can be the commonly used positive electrode active material in the current lithium ion battery, for example, at least one composite oxide of lithium and metals such as cobalt, manganese, nickel and combinations thereof, in detail, can be at least one of lithium cobaltate, lithium nickelate, lithium manganate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganate, lithium-rich manganese-based material, etc.

[0069] The preparation method of the solid-state battery provided by the embodiment of the present application first mixes Li 6+2x Al x P 1- x S 5-2x O 2x Cl in a stoichiometric ratio to obtain a mixed powder, wherein 0.01≤x≤0.08, then amorphous treatment is performed on the mixed powder to obtain a solid-state electrolyte powder precursor, then high-temperature sintering treatment is performed on the solid-state electrolyte powder precursor in an inert atmosphere to obtain a sulfide solid-state electrolyte, then the sulfide solid-state electrolyte is refined, and the refined sulfide solid-state electrolyte is mixed with a binder and pressed into an electrolyte layer, finally, the positive electrode sheet, the electrolyte layer and the lithium metal negative electrode sheet are assembled to obtain the solid-state battery. 3−The sulfide solid electrolyte doped with O elements and Al elements of the functional group reduces the air sensitivity of the sulfide solid battery used in the battery preparation process, thereby reducing the production cost of the battery. At the same time, the poor compatibility of the electrolyte and the lithium metal negative electrode interface in the battery is alleviated: the Li2O and Li-Al alloy formed by the contact of the electrolyte and the lithium metal negative electrode makes the performance of the battery more excellent, and improves the cycle performance and other electrochemical properties of the solid-state battery.

[0070] The second embodiment of the present application provides a solid-state battery, comprising: a positive electrode sheet, a lithium metal negative electrode sheet and a sulfide solid electrolyte.

[0071] The chemical formula of the sulfide solid electrolyte is Li 6+2x Al x P 1-x S 5-2x O 2x Cl, 0.01≤x≤0.08.

[0072] For example, x is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, or 0.08, or a new range is selected from any two of the foregoing values, and the value taken in the new range. Here, only examples are given, and the specific value can be determined according to the actual application scenario.

[0073] Preferably, 0.03≤x≤0.06.

[0074] In addition, in the solid-state battery provided by the present embodiment, the positive electrode sheet specifically comprises a positive electrode current collector and a positive electrode active layer formed by a positive electrode active material arranged on the surface of the positive electrode current collector. It should be understood that the present application does not strictly limit the positive electrode active material in the positive electrode sheet, which can be the positive electrode active material commonly used in lithium ion batteries at present, such as at least one composite oxide of lithium and metals of cobalt, manganese, nickel and combinations thereof. In detail, it can be at least one of lithium cobaltate, lithium nickelate, lithium manganate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganate, lithium-rich manganese-based material, etc.

[0075] In the solid-state battery provided by the present embodiment, the negative electrode sheet is a lithium metal negative electrode sheet made of lithium metal.

[0076] It should be noted that the solid-state battery provided by the present embodiment is prepared by the method provided in the above embodiment one.

[0077] The solid-state electrolyte provided by the embodiment is a sulfide solid-state electrolyte in which O elements partially replace S elements in a Li6PS5Cl type sulfide solid-state electrolyte, and Al elements partially replace P elements in the Li6PS5Cl type sulfide solid-state electrolyte. On the one hand, the PS4 3- group in the sulfide solid-state electrolyte is regulated to POS3 3- group, which can improve the air stability of the sulfide solid-state electrolyte. On the other hand, on the basis of weakening the side reaction between the sulfide solid-state electrolyte and the lithium metal negative electrode and reducing the content of impurities Li2S and impurities Li3P generated by the side reaction, the introduction of Al in the electrolyte can react with the lithium metal negative electrode to generate Li + The Li-Al alloy with high ion conductivity is uniformly deposited at the interface. The introduction of O in the electrolyte can react with the lithium metal negative electrode to generate Li2O with high ion conductivity, so as to improve the ion conductivity of the sulfide solid-state electrolyte on the basis of reducing the interface stability of the sulfide solid-state electrolyte to lithium metal. Further, the sulfide solid-state electrolyte with optimized air stability, interface stability to lithium metal, and ion conductivity is applied to the solid-state battery provided by the application, which can effectively improve the electrochemical performance of the solid-state battery provided by the application, including but not limited to cycle performance and ion conductivity.

[0078] The embodiment three of the application provides a power utilization device, which comprises a power utilization device body and the solid-state battery provided by the application.

[0079] It should be noted that the application does not particularly limit the type of power utilization device, which can be any power utilization equipment including the battery, including but not limited to electric vehicles, mobile phones, portable devices, notebook computers, electric bicycles, electric toys, energy storage devices, etc.

[0080] The application will be further described through specific embodiments. Unless otherwise specified, the reagents, materials and instruments used in the following embodiments are conventional reagents, conventional materials and conventional instruments in the field, which can be obtained by commercial purchase, and the reagents involved can also be obtained by conventional methods in the field.

[0081] Embodiment 1

[0082] Li2S, P2S5, LiCl and LiAlO2 were weighed in a powdering machine according to the stoichiometric ratio of 2.495:0.495:1:0.01, and were preliminarily mixed for 10 min to obtain a mixed powder;

[0083] The mixed powder was added to a ball mill jar and sealed, and ball milled at 500 rpm for 30 h using a planetary ball mill to obtain a solid electrolyte powder precursor;

[0084] The solid electrolyte powder precursor was sintered at a sintering temperature of 500°C in an inert atmosphere for 10 h to obtain a solid electrolyte with a composition of Li 6.02 Al 0.01 P 0.99 S 4.98 O 0.02 Cl sulfide solid electrolyte.

[0085] Example 2

[0086] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.51:0.49:1:0.02; the composition of the obtained sulfide solid electrolyte is Li 6.04 Al 0.02 P 0.98 S 4.96 O 0.04 Cl.

[0087] Example 3

[0088] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.515:0.485:1:0.03; the composition of the obtained sulfide solid electrolyte is Li 6.06 Al 0.03 P 0.97 S 4.94 O 0.06 Cl.

[0089] Example 4

[0090] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.52:0.48:1:0.04; the composition of the obtained sulfide solid electrolyte is Li 6.08 Al 0.04 P 0.96 S 4.92 O 0.08 Cl.

[0091] Example 5

[0092] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.525:0.475:1:0.05; the composition of the obtained sulfide solid electrolyte is Li 6.1 Al 0.05 P0.95 S 4.90 O 0.1 Cl.

[0093] Example 6

[0094] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.53:0.47:1:0.06; the composition of the sulfide solid electrolyte obtained is Li 6.12 Al 0.6 P 0.94 S 4.88 O 0.12 Cl.

[0095] Example 7

[0096] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.535:0.465:1:0.07; the composition of the sulfide solid electrolyte obtained is Li 6.14 Al 0.07 P 0.93 S 4.86 O 0.14 Cl.

[0097] Example 8

[0098] The difference from Example 1 is that the stoichiometric ratio of Li2S, P2S5, LiCl and LiAlO2 is 2.54:0.46:1:0.08; the composition of the sulfide solid electrolyte obtained is Li 6.16 Al 0.08 P 0.92 S 4.84 O 0.16 Cl.

[0099] Example 9

[0100] The difference from Example 1 is that the sintering temperature is 600°C; the sintering time is 5h.

[0101] Example 10

[0102] The difference from Example 1 is that the sintering temperature is 550°C; the sintering time is 8h.

[0103] Comparative Example 1

[0104] Li2S, P2S5 and LiCl are weighed according to the stoichiometric ratio of 5:1:2, and are preliminarily mixed in a powdering machine for 10min to obtain a mixed powder;

[0105] The mixed powder is added into a ball milling tank for sealing treatment, and a planetary ball mill is used to mill for 30 h at a rotating speed of 500 rpm to obtain a solid electrolyte powder precursor;

[0106] The solid electrolyte powder precursor is sintered in an inert atmosphere for 10 h at a sintering temperature of 500 °C to obtain a sulfide solid electrolyte with a composition of Li6PS5Cl.

[0107] The sulfide solid electrolyte prepared in the above examples and comparative examples is subjected to performance testing, and the testing content specifically includes:

[0108] (1) Air stability test:

[0109] 2 g of the sulfide solid electrolyte powder is taken and exposed to a dew point of -40 °C for 0 h and 4 h, respectively, and ion conductivity tests are performed, and based on the ion conductivities obtained by the two tests, the conductivity retention rate of the sulfide solid electrolyte is calculated, and the test results are shown in Table 1.

[0110] The ion conductivity test method includes: 100 mg of electrolyte powder is weighed and placed in a mold for pressure molding under a pressure of 300 MPa, and in the state of applying pressure, an electrochemical workstation is used to measure the impedance value of the electrolyte material at room temperature 25 °C by electrochemical impedance measurement method, and the real value of the impedance of the absolute minimum of the phase of multiple impedances is taken as the impedance value RSE of the electrolyte material. The ion conductivity is calculated using the resistance value.

[0111] Table 1 Air stability test results of sulfide solid electrolyte

[0112]

[0113] According to the test results in Table 1, the conductivity retention rate of the sulfide solid electrolyte corresponding to Examples 1-10 after exposure to a dew point of -40 °C for 4 h is significantly higher than that of Comparative Example 1, which shows that the double doping of Al and O on Li6PS5Cl can effectively improve the air stability of the solid electrolyte. Secondly, as the doping amount increases, the ion conductivity gradually decreases, but the air stability is enhanced, which shows that selecting a moderate doping amount can make the ion conductivity and air stability of the sulfide solid electrolyte at a relatively optimal level.

[0114] Therefore, using a sulfide solid electrolyte with high air stability to prepare a solid-state battery can ensure that the ion conductivity and other key properties of the sulfide solid electrolyte are not damaged during the preparation of the solid-state battery, thereby achieving the effect of optimizing the ion conductivity and storage life of the solid-state battery.

[0115] (2) Solid-state battery lithium metal interface stability test:

[0116] 100 mg of sulfide solid electrolyte powder was weighed into a mold and pressure-formed into an electrolyte sheet by a pressure of 300 MPa, and then lithium sheets were placed on both sides of the electrolyte sheet to form a symmetrical battery (test conditions: 0.1 mA / cm 2 Constant current test), the cycle time of the battery under this constant current condition was recorded to evaluate the interface stability between the electrolyte and lithium metal, and the test results are shown in Table 2.

[0117] Table 2 Test results of solid-state battery lithium metal interface stability

[0118]

[0119] According to the test results in Table 2, the cycle time of the sulfide solid electrolyte corresponding to Examples 1-10 is much longer than that of Comparative Example 1, and it can be seen that the double doping of Al and O on Li6PS5Cl can effectively improve the interface stability of the sulfide solid electrolyte to lithium metal. Taking the sulfide solid electrolyte with components Li 6.02 Al 0.01 P 0.99 S 4.98 O 0.02 Cl as an example, when the solid-state battery is working, the electrolyte can react with the surface of the metal lithium, and the sulfide solid electrolyte can reduce the content of impurities while forming a Li2O and Li-Al alloy interface, which can effectively promote the uniform deposition of lithium ions on the surface of lithium metal and inhibit the growth of lithium dendrites. Therefore, the sulfide solid electrolyte provided by the present application has excellent interface stability to lithium metal, and can optimize the electrochemical performance such as the cycle performance of the solid-state battery.

[0120] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a solid-state battery, characterized in that: The method comprises: According to the chemical formula Li 6+2x Al x P 1-x S 5-2x O 2x Li2S, P2S5, LiCl and LiAlO2 weighed in a stoichiometric ratio of 1:1 and 1:1 are preliminarily mixed to obtain a mixed powder, wherein 0.01≤x≤0.08; performing amorphization treatment on the mixed powder to obtain a solid electrolyte powder precursor; In an inert atmosphere, the solid electrolyte powder precursor is subjected to a high-temperature sintering treatment to obtain a sulfide solid electrolyte; After refining the sulfide solid electrolyte, the refined sulfide solid electrolyte is mixed with a binder and pressurized to form an electrolyte layer; The positive electrode sheet, the electrolyte layer and the lithium metal negative electrode sheet are assembled to obtain the solid-state battery.

2. The method according to claim 1, characterized in that 0.03≤x≤0.06。 3. The method according to claim 1, characterized in that The average particle size D of Li2S 50 3~50μm.

4. The method according to claim 1, wherein The average particle size D of Li2S 50 3~10μm.

5. The method according to any one of claims 1 to 4, characterized in that The amorphization treatment of the mixed powder to obtain a solid electrolyte powder precursor comprises: The mixed powder is placed in a ball milling jar and subjected to ball milling treatment by a ball mill to obtain the solid electrolyte powder precursor.

6. The method according to claim 5, characterized in that The ball milling speed of the ball milling treatment is 100-800 rpm; and / or the ball milling time of the ball milling treatment is 10-50 h.

7. The method according to claim 6, characterized in that The ball milling speed of the ball milling treatment is 500-800 rpm; and / or the ball milling time of the ball milling treatment is 30-40 h.

8. The method according to any one of claims 1 to 4, characterized in that The temperature of the high-temperature sintering treatment is 500-600°C.

9. The method according to claim 8, characterized in that The high temperature sintering treatment time is 5 to 10 hours.

10. A solid-state battery, characterized in that: The solid-state battery is a solid-state battery prepared by the method according to any one of claims 1 to 9.

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