Composite lithium salt (LiaMbPcSdNeXf) solid electrolyte containing chlorine, nitrogen, sulfur and phosphorus as well as preparation method and application of composite lithium salt (LiaMbPcSdNeXf) solid electrolyte

Abstract

The invention discloses a composite lithium salt (L iaMbPcSdNeXf) solid electrolyte of chlorine, nitrogen, sulfur and phosphorus, which is a composite lithium salt obtained by sintering multiple elements at high temperature, is a solid electrolyte material for a solid battery, and belongs to the technical field of lithium batteries. Wherein M represents a metal, P represents a phosphorus element, S represents a sulfur element, N represents a nitrogen element, X represents a halogen element, and a, b, c, d, e and f in the chemical formula represent atomic molar ratio values. The method comprises the following steps: weighing compounds such as lithium nitride, trilithium phosphide, phosphazene and derivatives in different proportions, blending, grinding and crushing to obtain a mixture, pressing the mixture into any shape or keeping a raw powder state, and sintering under atmosphere protection or vacuum to obtain the solid electrolyte applied to the solid battery. The invention belongs to the field of solid electrolyte of a solid-state battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion battery materials, and particularly relates to a composite lithium salt solid electrolyte containing chlorine, nitrogen, sulfur and phosphorus as well as a preparation method and application thereof. BACKGROUND

[0002] Current solid-state electrolytes are mainly divided into oxides, sulfides, polymers and halides. Currently, there are various solid-state electrolytes with industrialization prospects, such as: Li2S-P2S5, Li7P3S 11 , Li6PS5Cl, Li 11 Si2PS 12 , Li 10 SnP2S 12 , Li 10 GeP2S 12 , etc. The products developed based on sulfides have attracted great attention in the industry, and this multi-element composite hybrid method is a good solution. For example, sulfide electrolytes (such as Li2S-P2S5 series) have high ionic conductivity, but they are sensitive to air and have poor interface stability at high voltage. Halide electrolytes (such as LiCl) exhibit good oxidation stability, but the ionic conductivity is low. As lithium phosphorus sulfide chloride (Li6PS5Cl, LPSC) has a stable crystal structure and good lithium ion conductivity, it may play a key role in the development of all-solid-state batteries, but it still has the problem of high grain boundary lithium ion resistance. In addition, the use of lithium sulfide raw materials is prone to reaction in air, releasing toxic gases, which is not conducive to industrialization. Lithium aluminum titanium phosphate (LATP) and lithium aluminum germanium phosphate (LAGP) have attracted widespread attention from the industry due to their high ionic conductivity. The principle is that the structure is composed of PO4 tetrahedron and MO6 octahedron, and the ion transport network of the rhombohedron framework is connected by the top oxygen atoms. LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) is a solid-state electrolyte with high ionic conductivity of 10 -4 ~ 10 -3 S / cm at room temperature, has good chemical stability and high temperature performance, and the material preparation process is simple and easy to industrialize. LATP has high chemical stability to air in the production process and has application potential in lithium batteries. However, it still faces some challenges in practical application, such as high inter-particle interface resistance, which affects the transmission efficiency of lithium ions, and application is limited under large current charging and discharging conditions.

[0003] In recent years, there has been considerable research on the lithium-phosphorus-sulfur-chlorine solid electrolyte system. Publication No.: CN 113851629A discloses a method for preparing lithium-phosphorus-sulfur-chlorine for all-solid-state battery materials, specifically including the following steps: (1) mixing lithium compounds and phosphorus compounds, pressing into sheets, heat-treating, cooling, and then wet-milling to obtain a chlorine-based solid electrolyte; wherein, the lithium compound is a mixture of lithium sulfide and lithium chloride, and the phosphorus compound is a mixture of phosphorus pentasulfide and phosphorus pentachloride; (2) mixing resin and lithium salt uniformly to obtain an organic solid electrolyte; (3) mixing the chlorine-based solid electrolyte and the organic solid electrolyte uniformly to obtain a base material; (4) adding the base material to an impregnation liquid for impregnation, and then drying and curing under an inert gas atmosphere to obtain the lithium-phosphorus-sulfur-chlorine for all-solid-state battery materials. Publication No.: CN 115360407A describes a solid-state battery, including a positive electrode, a solid electrolyte, and a negative electrode stacked sequentially; the solid electrolyte includes the following components: a lithium-phosphorus-sulfur compound. Publication No.: CN 117747816 A discloses a method for preparing a cathode material, using at least one of molybdenum sulfide and cobalt sulfide as the metal sulfide; and / or the lithium phosphorus sulfide halide electrolyte as Li6PS5X, where X is a halogen. The preparation method involves in-situ generation of the lithium phosphorus sulfide halide electrolyte on the surface of the metal sulfide to obtain a modified metal sulfide; characterized in that the metal sulfide, lithium source, phosphorus source, halogen source, and solvent are mixed uniformly, and then distilled and heat-treated to generate the lithium phosphorus sulfide halide electrolyte in-situ on the surface of the metal sulfide, thereby obtaining the modified metal sulfide. Publication No.: CN 120341350 A discloses a method for preparing a solid electrolyte with high ionic conductivity, comprising the following steps: Under an inert atmosphere, lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide, and boron nitride are mixed to obtain a mixture; the mixture is ball-milled to obtain a precursor powder; the precursor powder is sintered; and the sintered precursor powder is dispersed to obtain a solid electrolyte with high ionic conductivity. The solid electrolyte is: Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 Cl

[0004] Publication No. CN 112520703 B discloses a green preparation method for lithium sulfide, involving the following chemical reaction equations: 2LiNH2+S+H2→Li2S+2NH3, Li2NH+S+H2→Li2S+NH3, 2Li3N+3S+3H2→3Li2S+2NH3. Publication No. CN 113614032 B discloses a method for manufacturing a lithium nitride composition, comprising: a step of nitriding lithium foil in nitrogen gas; a step of mechanically processing the obtained lithium nitride foil to form it into powder; and a step of annealing the obtained powdered lithium nitride. Publication No.: CN116216652 B, A method for preparing lithium sulfide, characterized in that the method includes the following steps: (1) reacting metallic lithium with introduced nitrogen gas in the presence of an inert atmosphere or under vacuum conditions to prepare lithium nitride, and controlling the residual amount of metallic lithium in the lithium nitride within a preset safety threshold range; (2) mixing the lithium nitride obtained in step (1) with elemental sulfur to react and obtain lithium sulfide. Publication No.: CN 120322143 A, Nanocomposite material, characterized in that it includes a combined first nanoparticle and a second nanoparticle; the first nanoparticle is a transition metal nanoparticle, and the transition metal in the transition metal nanoparticle is one or a combination of the following elements: iron, cobalt, nickel and gadolinium. The second nanoparticle is one or a combination of the following materials: lithium nitride nanoparticles, lithium oxide nanoparticles, lithium phosphide nanoparticles, lithium selenide nanoparticles and lithium sulfide nanoparticles; the nanocomposite material is used to prepare spin capacitors.

[0005] The aforementioned patent analysis and publicly available reports highlight the following industry pain points: the lithium conductivity at the electrolyte crystal interface needs improvement, and the products lack sufficient air stability. To address these issues, we propose introducing lithium nitride into the solid-state electrolyte to enhance grain boundary lithium-ion conductivity. Lithium nitride (Li3N) exhibits high lithium-ion conductivity and good stability in dry air at room temperature, but it rapidly releases ammonia gas in wet environments and readily reacts with other battery components, hindering its application in solid-state electrolytes. Therefore, introducing a metal halide and co-sintering it creates a multi-element symbiotic system to improve the solid-state electrolyte's resistance to hydrolysis. Additionally, lithium triphosphide is a phosphide with good lithium-ion conductivity. In this invention, the introduction of phosphorus can generate physical or chemical interactions with both sulfur and nitrogen elements, thereby improving the stability of sulfides and nitrides. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing solid electrolyte materials and prepare a novel solid electrolyte that utilizes the high conductivity of lithium nitride, lithium phosphide, and lithium sulfide, in conjunction with metal halides, to improve and overcome the unfavorable conditions of existing materials in terms of interfacial resistance, process flow, and production environment. A composite lithium salt containing chlorine, nitrogen, sulfur, and phosphorus (Li) is produced. a M b P c S d N e X f Solid electrolytes are used to improve the performance of lithium-phosphorus-sulfur-chloride solid electrolytes.

[0007] This invention uses no oxides in its raw material selection, employing sulfides, nitrides, and phosphides to construct high-conductivity lithium channels. Chlorine doping further improves the material's air stability and interfacial compatibility. The addition of metal M enhances the overall structural stability, and the battery maintains its good structure even after 1500 cycles. By precisely controlling the proportions of each component and the synthesis process, this invention yields a solid-state electrolyte that exhibits excellent ionic conductivity at room temperature; it also maintains good mechanical strength and structural characteristics at 150°C, making it suitable for the large-scale production of high-safety all-solid-state lithium batteries. Experimental results show that the ionic conductivity of this solid-state electrolyte at room temperature exceeds 1.5 × 10⁻⁶. -3 The material exhibits a capacitance of S / cm and can operate stably within a temperature range of -20℃ to 120℃. Furthermore, the material system is oxide-free, avoiding side reactions with the lithium metal anode and creating favorable application scenarios for lithium metal anodes. High-specific-capacity lithium metal anodes are considered excellent anode materials for solid-state batteries. The high-temperature sintering process provides a feasible path for large-scale production. This invention represents a unique discovery in material design and process control, laying the foundation for the industrial application of solid-state batteries.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A composite lithium salt containing chlorine, nitrogen, sulfur, and phosphorus (Li a M b P c S d N e X f The preparation method of solid electrolyte includes the following first step: mixing lithium sulfide, lithium nitride, lithium phosphide, aluminum chloride, etc. under an inert atmosphere;

[0010] The second step is to ball mill the mixture to obtain a precursor powder mixture;

[0011] Third, the precursor powder mixture is compressed or uncompressed (if compressed, the pressure is greater than 100 MPa) and then sintered. The sintering process includes heating, holding, and cooling.

[0012] The fourth step is to pulverize the sintered product to a certain mesh size, or to wire cut the compressed sintered product to obtain thin sheets smaller than 200 micrometers.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The objectives of the present invention can be better achieved and realized through the following preferred technical solutions.

[0014] According to the chlorine-nitrogen-sulfur-phosphorus composite lithium salt (Li) as described in the claim a M b P c S d N e X f Solid electrolytes, where M represents a metal, P is phosphorus, S is sulfur, N is nitrogen, and X is a halogen. In the chemical formula, a, b, c, d, e, and f represent atomic molar ratios. The synthesis methods for lithium triphosphide and lithium nitride are as follows:

[0015] (1) The preparation method of lithium phosphide is as follows: metallic lithium and elemental phosphorus are melted and reacted at high temperature under inert gas protection. The reaction temperature is between 450℃ and 800℃, and the temperature is maintained for 12 hours. After cooling, the mixture is crushed.

[0016] (2) The method for preparing lithium nitride is as follows: lithium metal is introduced into nitrogen gas, heated to 350℃-600℃, kept at the temperature for 6 hours, and then pulverized after cooling.

[0017] The chemical formula of the solid electrolyte is Li a M b P c S d N e X f The atomic molar ratio is calculated using the formula: (a+2b):(3c+2d+3e+f)=1:(0.2-2.5); or (a+3b):(3c+2d+3e+f)=1:(0.2-2.5), wherein Li is preferred. 8-12 AlP2S4N 1.5-3 Cl.

[0018] The method for preparing the solid electrolyte is characterized in that the materials selected are,

[0019] The sources of lithium elements include lithium metal, lithium nitride, lithium sulfide, lithium triphosphide, lithium phosphide, lithium chloride, lithium aluminum phosphide, etc.; preferably one, two or three of them.

[0020] M represents a metal, such as antimony, germanium, tin, aluminum, sodium, potassium, and magnesium; the material source is its nitride, sulfide, phosphide, or halide. One or two of aluminum chloride and magnesium nitride are preferred. P represents phosphorus, derived from materials such as lithium phosphide, trilithium phosphide, phosphazenes and their derivatives, lithium aluminum phosphide, and magnesium phosphide; one or two of trilithium phosphide, phosphazenes and their derivatives are preferred.

[0021] S represents sulfur, which comes from materials such as phosphorus pentasulfide, lithium sulfide, elemental sulfur, aluminum sulfide, or magnesium sulfide.

[0022] Aluminum sulfide is preferred; lithium sulfide or elemental sulfur are preferred, either one or both.

[0023] N represents nitrogen, which comes from materials such as lithium nitride, aluminum nitride, phosphazene and its derivatives, magnesium nitride, or nitrogen gas; preferably one or two of lithium nitride, aluminum nitride, or phosphazene and its derivatives.

[0024] X represents a halogen element; the halogen element comes from materials such as lithium fluoride, aluminum chloride, lithium chloride, magnesium chloride, aluminum bromide, lithium bromide, magnesium bromide, aluminum iodide, lithium iodide, and magnesium iodide, with lithium chloride, aluminum chloride, and magnesium chloride being preferred.

[0025] The chlorine-nitrogen-sulfur-phosphorus composite lithium salt (Li a M b P c S d N e X f The solid electrolyte, wherein the sintering process includes: placing the material in a crucible and sintering it in a muffle furnace; the sintering holding temperature is 650℃-1200℃, preferably 750℃-900℃, and the holding time is more than 1 hour, preferably 3-5 hours; the sintering atmosphere is a protective atmosphere or vacuum, preferably argon or nitrogen. After sintering, the material is naturally cooled to room temperature to obtain the solid electrolyte material.

[0026] The aforementioned chlorine-nitrogen-sulfur-phosphorus composite lithium salt (Li a M b P c S d N e X fSolid electrolytes, whose raw materials do not involve oxides, are preferably composed of lithium nitride, lithium triphosphide, phosphazenes and their derivatives, and lithium sulfide. These materials exhibit high reactivity and can rapidly decompose at high temperatures, releasing their corresponding elements, thus promoting the efficient synthesis of solid electrolytes and generating a symbiotic phase. Therefore, during the preparation of the solid electrolyte, it is crucial to control the molar ratio of the raw materials and the sintering temperature to effectively regulate the crystal structure and ionic conductivity of the product.

[0027] The aforementioned chlorine-nitrogen-sulfur-phosphorus composite lithium salt (Li a M b P c S d N e X f Solid electrolyte, preferably Li 8-12 AlP2S4N 1.5- 3Cl, the selected materials and their molar ratios are: lithium nitride: lithium triphosphide or phosphazene and its derivatives: lithium sulfide: aluminum chloride = 1.5-3.0: 1.8-2.2: 3.0-5.0: 0.8-1.2. Alternatively, lithium nitride: phosphorus pentasulfide: lithium sulfide: aluminum chloride = 2.5-3.5: 0.5-1.5: 0.6-1.2: 1.

[0028] The aforementioned chlorine-nitrogen-sulfur-phosphorus composite lithium salt (Li a M b P c S d N e X f For solid electrolytes, the materials must be mixed before sintering. Alternatively, the materials can be mixed and then compressed at a pressure greater than 100 MPa before sintering to obtain a blocky solid. The solid can then be wire-cut to obtain solid electrolyte sheets with a thickness of less than 200 micrometers. After surface impurity removal treatment, these sheets can be directly used for the assembly of all-solid-state batteries.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] Simple sulfide electrolytes (such as Li3PS4) have a narrow electrochemical window; reported lithium-sulfur-phosphorus electrolytes have a voltage < 2.5V vs. Li / Li. +Lithium nitride is easily oxidized by high-voltage cathode materials with higher energy density (such as high-nickel ternary NCM and lithium-rich manganese-based materials), leading to a shortened battery cycle life. Chloride electrolytes (such as LiTaCl6) have been proven to have excellent high-voltage stability, but their ionic conductivity is low. This invention improves electrochemical stability by introducing elements such as chlorine and aluminum, which have better intrinsic stability, while maintaining compatibility with higher-voltage cathodes. By introducing nitrogen and phosphorus elements with strong ionic conductivity, synergistic effects with lithium sulfide are achieved, reducing interfacial side reactions and improving overall performance. This product, formed through high-temperature sintering, exhibits high stability due to its multi-element symbiotic crystal structure. The multi-element symbiosis also improves the interfacial stability against the air environment. Notably, the presence of trace amounts of lithium nitride at the interface effectively reduces the impedance of the solid-solid interface, improving the battery's rate capability and cycle life. This product is stable to air, with a much lower sensitivity to air humidity than previously reported lithium sulfide-phosphorus electrolytes. This invention uses phosphorus pentasulfide, phosphazene, and their derivatives as raw materials to introduce sulfur, phosphorus, and nitrogen elements into the final product, effectively addressing the safety and convenience of the production process. In addition, the firing process requires precise control to reduce product instability caused by changes in crystal form. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the preparation method;

[0032] Figure 2 This is a SEM image of the cross-section of the solid electrolyte powder sintered part in Embodiment 1 of the present invention. Detailed Implementation

[0033] It should be noted that any modifications or equivalent substitutions to the protected content of this invention that are similar to the technical routes and solutions of this invention are considered to not depart from the scope of the technical solutions of this invention and should be covered within the protection scope of this invention.

[0034] To make the technical solutions and advantages clearer, the examples provided are only a portion of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by third parties in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] Example 1: Preparation of Li 10 AlP2S4N2Cl solid electrolyte powder

[0036] Step 1: Weigh out lithium nitride, lithium sulfide, phosphazene derivative, and aluminum chloride according to the molar ratio, i.e., 1.85 mol, 1.9 mol, 4.25 mol, and 1.1 mol, respectively. Grind them thoroughly in a mortar and pestle until homogeneous.

[0037] Step 2: Mix the above powders and grind them using a ball mill. Stop grinding when the powder particle size D50 reaches below 20 micrometers and remove the powder.

[0038] Step 3: Compress the ground and mixed powder using a compressor with a pressure greater than 100 MPa. Place the die-cast body into a crucible or on a ceramic plate, and then sinter it in a high-temperature sintering furnace under a nitrogen atmosphere. The sintering procedure is as follows: heat up at 2℃ / min, hold at 850℃ for 8 hours, then cool down at a rate of 10℃ / min until it reaches room temperature naturally.

[0039] Step 4: Remove the sintered die-cast body and wire cut it into thin sheets for later use. The diameter of the cut wire should be less than 100 micrometers.

[0040] Figure 2 The image shows a SEM image of the fracture surface of the sintered blocky solid. The image shows dense and large crystals, indicating that the sintered product is a multi-element symbiosis rather than a physical interface bond of the raw materials.

[0041] Example 2: Preparation of Li 9.4 AlP 1.9 S 3.8 N 2.85 Cl 0.95 solid electrolyte powder

[0042] Step 1: Weigh out lithium nitride, phosphorus pentasulfide, lithium sulfide, and aluminum chloride according to the molar ratio, i.e., take 2.85 mol, 0.95 mol, 0.9 mol, and 1 mol respectively. Grind them thoroughly in a mortar and pestle.

[0043] Step 2: Mix the above powders and grind them using a ball mill. Stop grinding when the powder particle size D50 reaches below 20 micrometers and remove the powder.

[0044] Step 3: The ground and mixed powder is directly placed into a crucible and then placed in a high-temperature sintering furnace for vacuum sintering. The sintering program is as follows: the temperature is increased by 2℃ / min, heated to 950℃ and held for 12 hours, then cooled down at a rate of 10℃ / min, and allowed to cool naturally to room temperature.

[0045] Step 4: After removing the sintered powder, grind it into powder with a particle size of less than 15 micrometers for later use.

[0046] Comparing the electrolytes obtained in Examples 1 and 2 with commercially available Li3PS4, the data shows that the ionic conductivity of the sample in this example is comparable to that of the commercially available Li3PS4. However, there is a significant difference in the amount of toxic hydrogen sulfide gas produced by the sample in response to air humidity. Li3PS4 readily releases hydrogen sulfide gas from water vapor in the air, while the amount released by the sample in Example 1 is only 1 / 5660 of that of Li3PS4. This clearly demonstrates the good stability of the material prepared in this example to air humidity.

[0047] The method for testing the stability of the sample under humid air conditions is as follows: Take 100 grams of sample, crush it to a D50 of 20 micrometers, and place it in a self-made sealed chamber with an effective volume of 300 liters at a temperature of 25℃ and a relative humidity of 75%. After 24 hours, test the gas released from the chamber, absorb the gas accordingly, and detect it using ion chromatography (IC). Ammonia and hydrogen chloride can be absorbed by hydrochloric acid solution of known concentration, hydrogen sulfide gas can be absorbed by sodium hydroxide solution of known concentration, and phosphine gas uses acidic potassium permanganate solution as the absorbent.

[0048] Example 1 Example 2 Comparative Example (Li3PS4) Ionic conductivity 1.5 x 10 -3 S / cm 1.0 x 10 -3 S / cm 1.4 x 10 -3 S / cm Hydrogen sulfide (micrograms) 0.05 2.3 283.0 Ammonia (micrograms) Not detected Not detected Not detected Hydrogen chloride (micrograms) Not detected Not detected Not detected Phosphine (micrograms) Not detected Not detected Not detected

[0049] As can be seen from the above embodiments and comparative examples, the chlorine-nitrogen-sulfur-phosphorus composite lithium salt solid electrolyte and its preparation method provided by the present invention, through multi-element symbiotic design and optimized sintering process, produce a solid electrolyte material with high ionic conductivity, a wide electrochemical stability window, and excellent air stability. In particular, the introduction of lithium nitride and aluminum halide, and the formation of a stable crystalline phase through high-temperature sintering, effectively solves the industry problems of air sensitivity and interfacial instability of traditional sulfide electrolytes. The process route of the present invention is clear, providing a high-performance, high-stability electrolyte material solution for the industrialization of all-solid-state lithium batteries.

Claims

1. A solid-state electrolyte comprising a complex lithium salt of chloronitrosulfophosphate, characterized in that, consisting of lithium element (Li), metal element (M), phosphorus element (P), sulfur element (S), nitrogen element (N) and halogen element (X), and the chemical general formula is Li a M b P c S d N e X f , wherein a, b, c, d, e and f represent the atomic molar ratio values, and the atomic molar ratio values satisfy: (a+2b):(3c+2d+3e+f)=1:(0.2-2.5); or (a+3b):(3c+2d+3e+f)=1:(0.2-2.5).

2. The solid-state electrolyte comprising a complex lithium salt of chlorothionophos according to claim 1, characterized in that, The metal element (M) is an antimony element, a germanium element, a tin element, an aluminum element, a sodium element, a potassium element, or a magnesium element.

3. A method for producing the solid-state electrolyte of the complex lithium salt of chlorothionophos according to claim 1 or 2, characterized in that, The method comprises the following steps: S1. Raw material preparation: providing an oxide-free lithium source, an M source, a phosphorus source, a sulfur source, a nitrogen source, and a halogen source; S2. Mechanical activation: mixing the raw materials in the inert atmosphere according to the molar ratio and performing high-energy ball milling until the D50 particle size of the mixed powder is less than 20 microns to obtain a precursor; S3. High-temperature sintering: sintering the precursor at 650-1200℃ under atmosphere protection or vacuum for not less than 1 hour to form a solid-state electrolyte material with a multi-element intergrowth phase.

4. The method of claim 3, wherein the method is characterized by, Before S3. the high-temperature sintering, the precursor is subjected to pressure forming by applying a pressure of not less than 100 MPa, and after sintering, a dense block is obtained.

5. The method of claim 3, wherein the method is characterized by, After S3. the high-temperature sintering, the obtained dense block is subjected to wire cutting to obtain an electrolyte sheet with a thickness of less than 200 microns.

6. The method of claim 5, wherein the method is characterized by, The wire diameter of the cutting wire used is less than 100 microns.

7. The method for preparing a chlorine, nitrogen, sulfur, and phosphorus-containing composite lithium salt solid-state electrolyte according to claim 3, characterized in that, The lithium source is selected from at least one of metallic lithium, lithium nitride, trilithium phosphide, lithium sulfide, or lithium phosphide; The M source is selected from at least one of a nitride, a sulfide, a phosphide, or a halide; The phosphorus source is selected from a nitrogen-phosphorus compound such as trilithium phosphide, phosphazene and derivatives, lithium phosphide, lithium aluminum phosphide, magnesium phosphide, or aluminum phosphide; The sulfur source is selected from diphosphorus sulfide, lithium sulfide, elemental sulfur, aluminum sulfide, or magnesium sulfide; The nitrogen source is selected from a nitrogen-phosphorus compound such as lithium nitride, aluminum nitride, phosphazene and derivatives thereof, magnesium nitride, or nitrogen gas; The halogen source is selected from lithium fluoride, aluminum chloride, lithium chloride, magnesium chloride, aluminum bromide, lithium bromide, magnesium bromide, aluminum iodide, lithium iodide, or magnesium iodide.

8. An all-solid-state electrochemical device comprising a positive electrode, a negative electrode, and an electrolyte layer, characterized by, The electrolyte layer comprises the composite lithium salt solid-state electrolyte according to claim 1 or 2.

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