A sulfide solid electrolyte stable to lithium metal, and a preparation method and application thereof

Abstract

The present application relates to the technical field of solid-state lithium battery, and particularly relates to a sulfide solid electrolyte stable to lithium metal, a preparation method and application thereof. The sulfide solid electrolyte comprises a core of sulfide solid electrolyte particles and a surface coating material coating the core; the sulfide solid electrolyte particles adopt a sulfide solid electrolyte material stable to lithium metal, and the surface coating material adopts a two-dimensional sheet material capable of reacting with lithium metal in situ to generate a high ionic conductive interface layer. The sulfide solid electrolyte provided by the present application can generate a high ionic conductive interface layer promoting uniform deposition of Li metal in situ during the cycle process of the solid-state lithium battery assembled by the sulfide solid electrolyte, effectively inhibits lithium dendrites during the cycle process of the sulfide-based solid-state lithium battery, and improves the cycle life of the solid-state lithium battery. The material preparation process is simple and easy to operate, the coating material improves the air stability of the modified sulfide electrolyte, and is suitable for industrial scale-up operation.

Description

Technical Field

[0001] This invention relates to the field of solid-state lithium battery technology, specifically to a lithium metal-stabilized sulfide solid electrolyte, its preparation method, and its application. Background Technology

[0002] Against the backdrop of achieving "dual-carbon" goals and the booming development of the new energy vehicle market with long range and high safety, all-solid-state lithium metal batteries, which combine high energy density and high safety, have attracted researchers' attention. High-ionic-conductivity solid-state electrolytes, as key materials in solid-state lithium batteries, determine the overall electrochemical performance of these batteries. Therefore, the research and development of electrochemically stable solid-state electrolytes with high ionic conductivity and low electronic conductivity is imperative and of great significance. Among solid-state electrolyte systems, sulfide electrolytes are favored due to their high ionic conductivity (>1×10⁻⁶). -3 S cm -1 Its superior machinability makes it stand out among many solid electrolytes and is considered one of the most promising electrolyte systems for the industrialization of solid-state batteries.

[0003] Although sulfide solid electrolytes possess advantages in both high ionic conductivity and good machinability, their application in solid-state lithium batteries is significantly hampered by drawbacks such as air instability and lithium dendrite growth. The former leads to H2S release, increasing production costs and causing environmental problems. The latter, lithium dendrite growth, can trigger battery short circuits and thermal runaway, posing significant safety hazards. Lithium dendrite formation is primarily due to interfacial side reactions between the sulfide electrolyte and lithium metal, as well as defects in the sulfide electrolyte itself causing uneven lithium metal deposition. Furthermore, the high electronic conductivity of sulfide electrolytes allows lithium dendrites to grow into the electrolyte, gradually penetrating it and ultimately causing a battery short circuit.

[0004] Invention CN 114524416 A discloses a lithium sulfide-coated sulfide solid electrolyte, its preparation method, and its application. The lithium sulfide (Li₂S) of this invention possesses high ionic conductivity and moderate interfacial energy, and can serve as a critical functional layer to mitigate the spontaneous reaction between metallic lithium and the solid electrolyte. However, Li₂S is extremely unstable in air, which is detrimental to large-scale production. Invention CN 115275332 A discloses a sulfide solid electrolyte material and its preparation method. This invention uses a composite material of a hydrophobic molecular layer and graphene nanoribbons coated on the surface of the sulfide electrolyte. This improves its stability in air and prevents direct contact and reaction between the sulfide and the lithium anode. However, the increased conductivity of the graphene nanoribbons may induce electron flow into the electrolyte, promoting lithium dendrite growth. Furthermore, the coating process of this invention is complex, costly, and difficult to industrialize. Invention CN 115548431 A discloses a solid electrolyte core-shell structure, its preparation method, and its application. This invention significantly improves the air stability of the solid electrolyte but does not address the interface problem between the sulfide electrolyte and lithium metal. Invention CN 112701345 A discloses a superhydrophobic material capable of conducting lithium ions, its preparation method, and its application. This invention uses a low surface energy material to coat a Thio-LISICON type sulfide solid electrolyte to improve its hydrophobicity and air stability, but it does not solve the problems of poor interface stability between the sulfide electrolyte and lithium metal, or lithium dendrite growth. Invention CN 113745651 A discloses a coated sulfide solid electrolyte, its preparation method, and its application. It uses an oxide solid electrolyte layer coated on the surface of the sulfide solid electrolyte particles to solve the problems of poor water stability of the sulfide solid electrolyte and electrochemical window mismatch when the sulfide solid electrolyte is mixed with the cathode material, but it does not solve the interface stability problem with lithium metal. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a lithium metal-stable sulfide solid electrolyte, its preparation method, and its application. The sulfide solid electrolyte provided by this invention can react with lithium metal in situ to generate a high ion conductivity interface layer, while also taking into account the (wet) air stability of the coated and modified sulfide electrolyte, which is beneficial for large-scale production.

[0006] Specifically, the first aspect of this invention provides a lithium metal-stabilized sulfide solid electrolyte, comprising: a core of sulfide solid electrolyte particles, and a surface coating material covering the core; the sulfide solid electrolyte particles are made of a lithium metal-stabilized sulfide solid electrolyte material, and the surface coating material is a two-dimensional sheet material capable of reacting in situ with lithium metal to generate a high ion conductivity interface layer. In this invention, the lithium metal-stabilized sulfide solid electrolyte material, by coating the surface of the sulfide solid electrolyte particles with a two-dimensional sheet material capable of reacting in situ with lithium metal to generate a high ion conductivity interface layer, compared to an uncoated sulfide electrolyte, allows the solid-state lithium battery assembled with the coated sulfide electrolyte to generate a high ion conductivity interface layer that promotes uniform Li metal deposition in situ during cycling, thereby effectively suppressing lithium dendrites during cycling and improving the cycle life of the solid-state lithium battery. The material preparation process is simple and easy to operate, and the coating material improves the air stability of the modified sulfide electrolyte, making it suitable for industrial-scale operation.

[0007] Preferably, the surface coating material is selected from one or more of non-metallic nitrides, transition metal sulfides, layered metal oxides, layered double hydroxides, layered metal carbides, metal nitrides or metal nitride-oxide composite two-dimensional materials, metal-organic framework materials, covalent organic framework materials, and perovskite materials; and / or, the surface coating material has hydrophobic properties; preferably, the surface coating material is selected from one or more of hexagonal boron nitride (h-BN), black phosphorus (BP), graphitic carbon nitride (g-C3N4), transition metal sulfides (TMDs), layered metal oxides, layered double hydroxides (LDHs), layered metal carbides, metal nitrides or metal nitride-oxide composite two-dimensional materials (MXene), metal-organic framework materials (MOFs), covalent organic framework materials (COFs), and perovskite materials.

[0008] Further preferably, the surface coating material is g-C3N4 and / or h-BN. In this invention, when the coating material is g-C3N4 and / or h-BN, the air stability of the modified sulfide electrolyte can be further improved, the cycle life of the solid-state lithium battery can be increased, and the large-scale production of surface-coated modified sulfide solid electrolyte can be better realized.

[0009] According to the present invention, the g-C3N4 is preferably g-C3N4 nanosheets obtained by calcination in a urea muffle furnace, and preferably, the calcination temperature is 550°C and the calcination time is 3 to 8 hours.

[0010] Preferably, the core is selected from (100-x)Li₂S-xP₂S₅, (100-x)Li₂S-xSiS₂, (100-x)Li₂S-xSnS₂, (100-x)Li₂S-xGeS₂, Li 4-x Ge 1-x P x S4, Li 11-y Ge 2-y P 1+y S 12 Li 11-y Sn 2-y P 1+y S 12 Li 11-y Si 2-y P 1+ y S 12 One or more of Li6PS5Cl, Li6PS5Br, Li6PS5I and Li3PS4; where 1>x>0, 1>y>0; preferably, the core is Li6PS5Cl.

[0011] Further preferably, the mass ratio of the sulfide solid electrolyte particles to the surface coating material is 99–1:1, more preferably 32–2:1. In this invention, by optimizing the ratio of the sulfide solid electrolyte particles to the surface coating material, the coating material effectively coats the surface of the sulfide solid electrolyte particles, thereby significantly improving the air stability of the surface-coated sulfide solid electrolyte to lithium metal.

[0012] The method for preparing the lithium metal-stabilized sulfide solid electrolyte provided in the second aspect of the present invention includes coating the surface of the sulfide solid electrolyte particles with the surface coating material; preferably, it is prepared by mechanical ball milling.

[0013] Preferably, the above-mentioned method for preparing lithium metal-stabilized sulfide solid electrolyte includes adding a mixed powder of the surface coating material and the sulfide solid electrolyte particles into a high-energy ball mill with zirconia balls under an inert atmosphere for ball milling; preferably, the ball milling speed is 50-500 r / min and the ball milling time is 1-20 h.

[0014] Further preferably, the ball milling speed is 100–300 r / min, and the ball milling time is 5–15 h; more preferably, it is 200 ± 50 r / min, and the ball milling time is 12 ± 2 h. In this invention, by optimizing the ball milling parameters, the coating material is successfully coated onto the surface of the sulfide solid electrolyte particles, and a better coating effect can be achieved, especially by ball milling at a speed of 100–300 r / min for 5–15 h.

[0015] Further preferably, the mass ratio of the zirconia spheres to the mixed powder is 35–45:1; and / or, the inert atmosphere protection is Ar atmosphere protection.

[0016] Further preferred embodiments include lithium metal-stable sulfide solid electrolytes prepared in an Ar atmosphere.

[0017] The application of the lithium metal-stable sulfide solid electrolyte provided in the second aspect of the present invention, or the lithium metal-stable sulfide solid electrolyte prepared from the above-mentioned lithium metal-stable sulfide solid electrolyte, in the preparation of solid-state lithium metal batteries.

[0018] The beneficial results of this invention are at least as follows:

[0019] 1) This invention uses a two-dimensional sheet material that is stable to lithium metal to coat a sulfide solid electrolyte. The coating material can react with lithium metal in situ to generate a high ion conductivity interface layer, which can greatly improve the ability of the sulfide electrolyte to suppress lithium dendrites and extend its cycle life.

[0020] 2) The coating material of this invention is both hydrophobic and insensitive to moisture in the air, which can effectively inhibit the hydrolysis reaction of the sulfide electrolyte after coating modification. Moreover, the coating process is simple and easy to scale up. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The Li-LiNi assembled according to Examples 1-3 and Comparative Example 2 provided by this invention 0.6 Co 0.2 Mn 0.2 O2 full battery performance test at 0.1C;

[0023] Figure 2 Ion conductivity tests of the sulfide solid electrolytes prepared in Example 2 and Comparative Example 2 before and after air exposure, provided by the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] Unless otherwise specified in the embodiments of this invention, the techniques or conditions described in the literature in this field, or the product instructions, shall apply. Devices, instruments, reagents, etc., whose manufacturers are not specified, are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market. In the embodiments of this invention, the high-energy ball mill used is a Pulverisette 6 high-energy planetary ball mill.

[0026] Example 1

[0027] Urea was placed in crucibles (2g of urea per crucible) and calcined at 550℃ for 5h in an air-atmospheric furnace to obtain g-C3N4 nanosheets. The sulfide electrolyte Li6PS5Cl (Guolian Automotive Power Battery Research Institute, abbreviated as 651) and the above-mentioned g-C3N4 were added to a high-energy ball mill jar equipped with zirconia balls at a mass ratio of 97:3, wherein the mass ratio of zirconia balls to the mixed powder (sulfide electrolyte Li6PS5Cl and g-C3N4) was 40:1, with a total mass of 25.5g. The ball milling speed was set to 200r / min, with each cycle consisting of 7min of ball milling time and 3min of settling time, for a total of 72 cycles and a total ball milling time of 12h. 3wt% g-C3N4-coated sulfide solid electrolyte powder (abbreviated as 651-3%) was collected in an Ar atmosphere glove box.

[0028] Electrochemical performance tests were performed on the all-solid-state lithium battery assembled using the sulfide solid electrolyte powder 651-3% prepared in this embodiment. The all-solid-state battery assembly process is as follows: 3 wt% g-C3N4-coated sulfide solid electrolyte powder was weighed and placed into a pressure mold with a diameter of 10 mm and pressurized to 2t. Then, 6 mg of positive electrode material was weighed. The positive electrode material consisted of 0.7 g LiNbO3-coated LiNi. 0.6 Co 0.2 Mn 0.2 O2 (coating thickness 5nm) and 0.3g Li6PS5Cl were hand-milled for 10 min to obtain the mixture, which was then added to one side of the electrolyte sheet. The pressure was increased to 4t and held constant for 1 min. Then, a lithium sheet was added to the other side of the electrolyte sheet, and the pressure was increased to 0.5t and held constant for 1 min. The assembled mold battery was tested under a constant current of 0.1C. The test voltage range was 2.5–4.3V, and the test temperature was room temperature.

[0029] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 71.4 mAh g after 200 cycles. -1 The capacity retention rate was 51.9%.

[0030] Example 2

[0031] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 72 cycles and a total ball milling time of 12 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder (referred to as 651-5%) was collected in an Ar atmosphere glove box. The sulfide solid electrolyte powder prepared in this embodiment was subjected to transmission electron microscopy (TEM) testing, which verified that the sulfide solid electrolyte prepared by the method of this invention has a coated structure, with g-C3N4 uniformly coated on the surface of Li6PS5Cl, and the coating layer thickness was approximately 5 nm.

[0032] Electrochemical performance tests were conducted on the all-solid-state lithium battery assembled using the sulfide solid electrolyte powder 651-5% prepared in this embodiment. The assembly process and electrochemical performance testing scheme for the all-solid-state battery were the same as in Example 1. The discharge specific capacity of the all-solid-state battery assembled in this embodiment after 200 cycles was 132.8 mAh g. -1 The capacity retention rate was 99.1%.

[0033] The procedure for humid air exposure of 651-5% powder: Equal masses of 651-5% powder were placed in open vials and then left to stand for 3 hours in a sealed glove box with a relative humidity of 20%. Powder was collected before and after air exposure and ionic conductivity was tested. The procedure for ionic conductivity testing: 100 mg of 651 sulfide solid electrolyte powder was weighed and placed in a 10 mm diameter pressure mold. After pressurizing to 2 tons, 10 mm diameter carbon-coated aluminum foil was added to both sides of the electrolyte sheet. A further 2 tons of pressure was applied, and the mold was tightened with a wrench to ensure tight contact between all parts of the battery. Finally, the gaps at the battery interface were sealed with a plastic sealant. Subsequent AC impedance testing was performed using an electrochemical workstation. The test frequency range was 1 Hz to 1 MHz.

[0034] Fitting the measured impedance curves, the ionic conductivity of the 651-5% sulfide electrolyte powder before and after air exposure is calculated to be 0.6 × 10⁻⁶. -3 S / cm and 0.45S / cm ( Figure 2 ).

[0035] Example 3

[0036] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 90:10, with the mass ratio of zirconia balls to mixed powder being 40:1, and the total mass being 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 72 cycles and a total ball milling time of 12 h. 10 wt% of g-C3N4-coated sulfide solid electrolyte powder (abbreviated as 651-10%) was collected in an Ar atmosphere glove box.

[0037] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-10% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0038] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 47.5 mAh g after 200 cycles. -1 The capacity retention rate was 36.0%.

[0039] Example 4

[0040] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 70:30, where the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time. 72 cycles were performed for a total ball milling time of 12 h. 30 wt% of g-C3N4-coated sulfide solid electrolyte powder (referred to as 651-30%) was collected in an Ar atmosphere glove box.

[0041] Electrochemical performance tests were conducted on all-solid-state lithium batteries assembled from 651-30% of the sulfide solid electrolyte powder prepared in this embodiment. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0042] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 1.35 mAh g after 200 cycles. -1 The capacity retention rate was 11.3%.

[0043] Example 5

[0044] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 30 cycles and a total ball milling time of 5 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0045] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0046] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 90.6 mAh g after 200 cycles. -1 The capacity retention rate was 88.1%.

[0047] Example 6

[0048] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 60 cycles and a total ball milling time of 10 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0049] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0050] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 100.7 mAh g after 200 cycles. -1 The capacity retention rate was 90.2%.

[0051] Example 7

[0052] The sulfide electrolytes Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, with the mass ratio of zirconia balls to mixed powder being 40:1, and the total mass being 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 15 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0053] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0054] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 131.3 mAh g after 200 cycles. -1 The capacity retention rate was 96.2%.

[0055] Example 8

[0056] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 100 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 15 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0057] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0058] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 100.3 mAh g after 200 cycles. -1 The capacity retention rate was 86.2%.

[0059] Example 9

[0060] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 300 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 12 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0061] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0062] The all-solid-state battery assembled in this embodiment has a discharge specific capacity of 99.8 mAh g after 200 cycles. -1The capacity retention rate was 84.1%.

[0063] Example 10

[0064] The sulfide electrolytes Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, with the mass ratio of zirconia balls to mixed powder being 40:1, and the total mass being 25.5 g. The ball milling speed was set to 400 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 15 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0065] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0066] The all-solid-state battery assembled in this embodiment exhibits a discharge specific capacity of 99.8 mAh g after 200 cycles. -1 The capacity retention rate was 84.1%.

[0067] Example 11

[0068] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 95:5, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 50 r / min, and each cycle consisted of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 15 h. 5 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0069] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-5% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0070] The all-solid-state battery assembled in this embodiment exhibits a discharge specific capacity of 99.1 mAh g after 200 cycles. -1 The capacity retention rate was 87.2%.

[0071] Example 12

[0072] The sulfide electrolyte Li6PS5Cl and g-C3N4 were added to a high-energy ball mill jar containing zirconia balls at a mass ratio of 97:3, wherein the mass ratio of zirconia balls to mixed powder was 40:1, and the total mass was 25.5 g. The ball milling speed was set to 200 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time, for a total of 90 cycles and a total ball milling time of 15 h. 3 wt% g-C3N4-coated sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0073] The electrochemical performance of the all-solid-state lithium battery assembled from the sulfide solid electrolyte powder 651-3% prepared in this example was tested. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as in Example 1.

[0074] The all-solid-state battery assembled in this embodiment exhibits a discharge specific capacity of 100.1 mAh g after 200 cycles. -1 The capacity retention rate was 86.9%.

[0075] Comparative Example 1

[0076] The sulfide electrolyte Li6PS5Cl was added only to a high-energy ball mill jar containing zirconia balls, with a mass ratio of zirconia balls to Li6PS5Cl powder of 40:1 and a total mass of 25.5 g. The ball milling speed was set to 300 r / min, with each cycle consisting of 7 min of ball milling time and 3 min of settling time. 72 cycles were performed for a total ball milling time of 12 h. The ball-milled sulfide solid electrolyte powder was collected in an Ar atmosphere glove box.

[0077] The ball-milled sulfide electrolyte Li6PS5Cl powder of this comparative example was used to assemble an all-solid-state lithium battery for electrochemical performance testing. The assembly process and electrochemical performance testing scheme of the all-solid-state battery were the same as those in Example 1.

[0078] The solid-state battery assembled using this comparative example exhibits a discharge specific capacity of 26.4 mAh g⁻¹ after 200 cycles. -1 The capacity retention rate was 18.4%.

[0079] Comparative Example 2

[0080] Electrochemical performance tests were conducted on all-solid-state lithium batteries assembled from un-ball-milled sulfide electrolyte Li6PS5Cl powder. The assembly process and electrochemical performance testing scheme were the same as in Example 1. The ion conductance test procedure for the un-ball-milled sulfide electrolyte Li6PS5Cl after air exposure was the same as in Example 2. The discharge specific capacity of the solid-state battery assembled in this example after 200 cycles was 26.9 mAh g. -1 The capacity retention rate was 18.9%.

[0081] The humid air exposure experiment and ionic conductivity test procedures for 651 powder were the same as in Example 2. Fitting the measured impedance curves, the ionic conductivity of the 651 sulfide electrolyte powder before and after air exposure was found to be 1.82 × 10⁻⁶. -3 S / cm and 0.95×10 -3 S / cm ( Figure 2 ).

[0082] The cycle performance of the sulfide all-solid-state lithium batteries assembled in Examples 1-3 (651-3%, 651-5%, 651-10%) and Comparative Example 2 (651) at 0.1C is as follows: Figure 1 As shown. Performance comparison reveals that the g-C3N4 coating, especially the 5wt% g-C3N4 coating, used in this application's embodiments effectively suppresses lithium dendrite growth and improves the cycle performance of sulfide-based solid-state lithium batteries. The use of the aforementioned two-dimensional sheet material, which can react in situ with lithium metal to generate a high-ion-conductivity interface layer, to coat the sulfide solid electrolyte is of great significance for developing sulfide-based solid-state lithium metal batteries with high safety, high specific energy, and long lifespan. This invention utilizes the hydrophobic properties of specific coating materials to effectively suppress the hydrolysis reaction of the sulfide electrolyte and slow down the decrease in ion conductivity, such as... Figure 2 As shown. The coating process of this invention is simple and easy to scale up.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sulfide solid-state electrolyte stable to lithium metal, characterized by, The sulfide solid electrolyte particle comprises a core and a surface coating material coating the surface of the core; the sulfide solid electrolyte particle adopts a sulfide solid electrolyte material stable to lithium metal, the surface coating material adopts a two-dimensional sheet material capable of reacting with lithium metal in situ to form a high-ionic-conductivity interface layer; the surface coating material is g-C3N4 and / or h-BN; and the mass ratio of the sulfide solid electrolyte particle to the surface coating material is 32-2:

1. The surface coating material is coated on the surface of the sulfide solid electrolyte particle; and the coating is achieved by mechanical ball milling.

2. The sulfide solid-state electrolyte stable to lithium metal according to claim 1, characterized by, said core is selected from one or more of (100-x)Li2S-xP2S5, (100-x)Li2S-xSiS2, (100-x)Li2S-xSnS2, (100-x)Li2S-xGeS2, Li 4- x Ge 1-x P x S4, Li 11-y Ge 2-y P 1+y S 12 , Li 11-y Sn 2-y P 1+y S 12 , Li 11-y Si 2-y P 1+y S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I and Li3PS4; in the formula, 1 > x > 0, 1 > y > 0.

3. The method of producing a sulfide solid-state electrolyte stable to lithium metal according to claim 1 or 2, characterized by, The mixed powder of the surface coating material and the sulfide solid electrolyte particle is added into a high-energy ball milling device with zirconia balls under protection of an inert atmosphere for ball milling.

4. The method of making a sulfide solid-state electrolyte stable to lithium metal according to claim 3, wherein, The ball milling speed is 50-500 r / min, and the ball milling time is 1-20 h.

5. The method of making a sulfide solid state electrolyte stable to lithium metal according to claim 4, wherein, The ball milling speed is 100-300 r / min, and the ball milling time is 5-15 h.

6. The method of making a sulfide solid state electrolyte stable to lithium metal according to claim 5, wherein, The mass ratio of the zirconia balls to the mixed powder is 35-45:1; and / or the inert atmosphere protection is Ar atmosphere protection.

7. The method of making a sulfide solid-state electrolyte stable to lithium metal according to any one of claims 4-6, wherein, 8. Use of the sulfide solid electrolyte stable to lithium metal according to claim 1 or 2 or the sulfide solid electrolyte stable to lithium metal prepared according to any one of claims 3-7 in the preparation of a solid-state lithium metal battery. ​

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