Modified solid electrolyte, preparation method thereof and all-solid-state lithium ion battery

Abstract

The invention provides a modified solid electrolyte, a preparation method thereof and an all-solid-state lithium ion battery, and belongs to the technical field of all-solid-state lithium ion battery manufacturing. The modified solid electrolyte is of a core-shell structure, an inner core is made of inorganic solid electrolyte, a shell is made of lithium-free metal sulfide, and the modified solid electrolyte can effectively solve the problem that the inorganic solid electrolyte is poor in air stability, so that the corresponding all-solid-state lithium ion battery has relatively excellent cycle performance.

Description

Technical Field

[0001] The present application relates to the technical field of all-solid-state lithium-ion battery manufacturing, and specifically to a modified solid-state electrolyte and a preparation method thereof, and an all-solid-state lithium-ion battery. Background Art

[0002] In existing technologies, all-solid-state electrolytes have received widespread attention due to their advantages such as high safety, high energy density, long cycle life, and a wide temperature range of application. However, inorganic solid electrolytes in all-solid-state electrolytes still have some problems in their application. For example, sulfide solid electrolytes and halide solid electrolytes in inorganic solid electrolytes both have poor air stability, which in turn leads to poor cycling performance of the corresponding batteries. Summary of the Invention

[0003] The purpose of this application is to provide a modified solid electrolyte and its preparation method, and an all-solid-state lithium-ion battery, which can effectively improve the problem of poor air stability of inorganic solid electrolytes, so that the corresponding all-solid-state lithium-ion battery has relatively excellent cycle performance.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a modified solid electrolyte, which has a core-shell structure, wherein the core is made of an inorganic solid electrolyte and the shell is made of a lithium-free metal sulfide.

[0006] In the above technical solution, the surface of the inorganic solid electrolyte core material has a shell layer of a lithium-free metal sulfide material. Compared with inorganic solid electrolytes, lithium-free metal sulfides have more ideal air stability. The use of lithium-free metal sulfides to coat inorganic solid electrolytes can, on the one hand, effectively improve the air stability of the inorganic solid electrolyte and also ensure that the coated solid electrolyte still has a relatively ideal ionic conductivity. On the other hand, the lithium-free metal sulfide can isolate the inorganic solid electrolyte from the coating, and can also improve the problem of side reactions that are prone to occur after the inorganic solid electrolyte is in direct contact with the active material (specifically, sulfide solid electrolytes are prone to harmful interfacial side reactions after direct contact with active materials, especially high-voltage positive electrodes and lithium metal negative electrodes; halide solid electrolytes are easily reduced to form metal-containing elements after direct contact with lithium metal, and are prone to redox reactions during charge and discharge after direct contact with high-voltage positive electrodes, resulting in the destruction of the structural integrity of the positive electrode), thereby enabling the corresponding all-solid-state lithium-ion battery to have relatively excellent cycle performance.

[0007] In some optional embodiments, the metal sulfide is selected from at least one of FeS, CuS and Ag2S.

[0008] In the above technical solution, the inorganic solid electrolyte is coated with the above-mentioned type of metal sulfide, which can more effectively improve the air stability of the inorganic solid electrolyte, so that the corresponding all-solid-state lithium-ion battery has better cycle performance.

[0009] In some optional embodiments, the thickness of the shell is 0.1 nm to 1000 nm; optionally, the thickness of the shell is 0.5 to 10 nm.

[0010] In the above technical solution, limiting the thickness of the shell within the above range can better take into account the air stability and ionic conductivity of the modified solid electrolyte; further, limiting the thickness of the shell within the range of 0.5 to 10 nm can better take into account the air stability and ionic conductivity of the modified solid electrolyte.

[0011] In some optional embodiments, the inorganic solid electrolyte is selected from at least one of a sulfide solid electrolyte and a halide solid electrolyte.

[0012] In the above technical solution, the coating layer provided in the embodiment of the present application can be well adapted to sulfide solid electrolytes and halide solid electrolytes.

[0013] In some optional embodiments, the inorganic solid electrolyte is a sulfide solid electrolyte, and the material of the sulfide solid electrolyte is Li6PS5Cl; or / and, the inorganic solid electrolyte is a halide solid electrolyte, and the material of the halide solid electrolyte is Li3InCl6.

[0014] In the above technical solution, the coating layer provided in the embodiment of the present application can be well adapted to Li6PS5Cl and Li3InCl6.

[0015] In a second aspect, an embodiment of the present application provides a method for preparing a modified solid electrolyte as provided in the embodiment of the first aspect, using atomic layer deposition technology to generate lithium-free metal sulfide on the surface of an inorganic solid electrolyte to form a modified solid electrolyte with a core-shell structure.

[0016] In the above technical solution, atomic layer deposition technology is used to form a lithium-free metal sulfide shell on the surface of the inorganic solid electrolyte, so that the prepared shell has the advantages of relatively uniform thickness, high density and high coverage rate of the core.

[0017] In some optional embodiments, the step of generating a lithium-free metal sulfide on the surface of an inorganic solid electrolyte using an atomic layer deposition technique to form a modified solid electrolyte having a core-shell structure includes:

[0018] S1 places an inorganic solid electrolyte in a reaction chamber of an atomic layer deposition device, wherein the reaction chamber is in a vacuum state and the temperature is maintained at 50-400°C; S2 transports a gaseous metal compound into the reaction chamber for sealing treatment so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S3 uses an inert gas to purge the reaction chamber to remove the gaseous metal compound remaining in the reaction chamber; S4 transports a gaseous sulfur source into the reaction chamber so that the gaseous sulfur source and the precursor layer react to generate metal sulfide; S5 uses an inert gas to purge the reaction chamber to remove the gaseous sulfur source remaining in the reaction chamber; S6 repeats steps S2-S5 multiple times to form a modified solid electrolyte with a core-shell structure; optionally, steps S2-S5 are repeated 10-50 times.

[0019] In the above technical solution, the above-described process is used to form a lithium-free metal sulfide shell layer on the surface of the inorganic solid electrolyte core, with relatively uniform thickness, high density, and high core coverage. The reaction chamber temperature is maintained within the above-described range to ensure that the gaseous metal compound remains in a gaseous state before being loaded onto the core, thereby facilitating the sufficient loading of the vaporized metal compound onto the surface of the inorganic solid electrolyte to form a precursor layer. Furthermore, steps S2 to S5 are repeated 10 to 50 times to ensure that the prepared shell has a suitable thickness, thereby ensuring that the resulting modified solid electrolyte has both ideal air stability and ionic conductivity.

[0020] In some optional embodiments, the step of transporting the gaseous metal compound into the reaction chamber for sealing treatment so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer includes:

[0021] S21 transports the gaseous metal compound into the reaction chamber for sealing treatment, wherein the pulse gas pressure for transporting the gaseous metal compound is 200-400 mTorr, and the sealing treatment time is 0.5-2 min, so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S22 uses an inert gas to purge the reaction chamber to remove the residual gaseous metal compound in the reaction chamber; S23 repeats steps S21-S22 multiple times; optionally, repeats steps S21-S22 4-6 times.

[0022] In the above technical solution, a precursor layer is formed on the surface of the inorganic solid electrolyte through repeated deposition. During each deposition process, the pulse gas pressure for delivering the gaseous metal compound and the sealing treatment time are respectively limited to the above-mentioned ranges, so that the gaseous metal compound can be relatively saturatedly covered on the entire surface of the core, thereby allowing the shell formed by the subsequent reaction to relatively completely and evenly coat the entire core. Furthermore, repeating steps S21 and S22 4 to 6 times can better balance the completeness, uniformity, and coating efficiency of the gaseous metal compound coating on the core surface.

[0023] In some optional embodiments, the step of purging the reaction chamber with an inert gas to remove residual gaseous metal compounds in the reaction chamber includes:

[0024] S31 delivers an inert gas into a reaction chamber in a vacuum state, wherein the pulse gas pressure of the delivered inert gas is 8000-9000 mTorr; S32 vacuums the reaction chamber to remove the inert gas in the reaction chamber; S33 repeats steps S31-S32 multiple times; optionally, repeats steps S31-S33 3-5 times.

[0025] In the above technical solution, by repeatedly purging the reaction chamber with an inert atmosphere and limiting the pulse pressure of the inert gas delivered each time to within the above range, residual gaseous metal compounds and any gaseous impurities that may be generated in the reaction chamber can be effectively removed. Furthermore, by repeating steps S31 and S32 three to five times, residual gaseous metal compounds in the reaction chamber can be more thoroughly removed.

[0026] In some optional embodiments, the step of delivering a gaseous sulfur source into the reaction chamber to react the gaseous sulfur source with the precursor layer to form a metal sulfide comprises:

[0027] In step S41, a gaseous sulfur source is transported into a reaction chamber for a sealed treatment, wherein the pulse gas pressure for transporting the gaseous metal compound is 200 to 400 mTorr and the reaction time is 0.5 to 2 minutes, so that the gaseous sulfur source reacts with the precursor layer to generate metal sulfide. In step S42, an inert gas is used to purge the reaction chamber to remove the residual gaseous sulfur source in the reaction chamber. In step S43, steps S41 to S42 are repeated multiple times. Optionally, steps S41 to S42 are repeated 4 to 6 times.

[0028] In the above technical solution, during the reaction between the gaseous sulfur source and the precursor layer to form the metal sulfide, the gaseous sulfur source is repeatedly delivered to the reaction chamber, and the pulse pressure and reaction time of each delivery of the gaseous sulfur source are controlled within the above-mentioned ranges. This allows the precursor layer to fully contact and react with the gaseous sulfur source, thereby ensuring that the shell formed by the reaction can relatively completely and evenly cover the entire core. Furthermore, steps S41 and S42 are repeated 4 to 6 times to ensure more complete contact and reaction between the precursor layer and the gaseous sulfur source.

[0029] In some optional embodiments, the material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t BuAMD)2, Fe(acac)3, Ag(fod)(PEt3), [Cu( i PrAMD)]2 and Cu(acac)2 at least one; Optionally, the material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t At least one of BuAMD)2, Fe(acac)3.

[0030] The above-mentioned technical solutions are applicable to a wide variety of gaseous metal compounds, providing a wide range of feasible implementation options, thereby facilitating the promotion and application of the technical solutions provided by the embodiments of the present application. Furthermore, the use of the above-mentioned iron-containing gaseous metal compounds, after forming a metal sulfide shell, significantly improves the air stability of the inorganic solid electrolyte, and accordingly, the corresponding all-solid-state lithium-ion battery also has better cycling performance.

[0031] In some optional embodiments, the material of the gaseous sulfur source is selected from at least one of dimethyl sulfide and hydrogen sulfide.

[0032] In the above technical solution, the above-mentioned type of gaseous sulfur source can react with the metal compound to form metal sulfide relatively easily and efficiently, and also has the advantages of being safe, portable and environmentally friendly.

[0033] In a third aspect, an embodiment of the present application provides an all-solid-state lithium-ion battery, which includes a positive electrode sheet, a solid electrolyte membrane and a negative electrode sheet, and the solid electrolyte membrane is located between the positive electrode sheet and the negative electrode sheet; wherein, at least one of the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet includes the modified solid electrolyte provided in the embodiment of the first aspect.

[0034] In the above technical solution, the functional unit in the all-solid-state lithium-ion battery (at least one of the positive electrode sheet, solid electrolyte membrane and negative electrode sheet) includes the modified solid electrolyte provided by the first embodiment. Since the modified solid electrolyte has relatively ideal air stability and relatively suitable ionic conductivity, the corresponding all-solid-state battery has relatively excellent cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A process flow chart of a method for preparing a modified solid electrolyte provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0038] It should be noted that “and / or” in this application, such as “Feature 1 and / or Feature 2”, refers to three situations: “Feature 1” alone, “Feature 2” alone, or “Feature 1” plus “Feature 2”.

[0039] In addition, in the description of this application, unless otherwise specified, the meaning of "multiple" in "one or more" refers to two or more; the range of "value a to value b" includes the two end values ​​"a" and "b", and the "unit of measurement" in "value a to value b+unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0040] In the prior art, to address the problem of poor air stability of inorganic solid electrolytes, providing a coating shell on their surface is a commonly used modification method. For example, patent CN117199511A uses a sulfide solid electrolyte shell to coat the sulfur-containing solid electrolyte core. However, in reality, the shell of this type of material still has the problem of poor air stability, which makes it difficult to effectively improve the air stability of inorganic solid electrolytes.

[0041] It should be noted that for sulfide solid electrolytes, their poor air stability is reflected in their sensitivity to water and oxygen in the air. During the preparation, transportation and use, they are easily exposed to water and oxygen, resulting in side reactions and decomposition, which leads to a decrease in ionic conductivity. For halide solid electrolytes, their poor air stability is reflected in their sensitivity to water in the air. During the preparation, transportation and use, they are easily exposed to moisture and decompose, which leads to a decrease in ionic conductivity.

[0042] Based on this, the inventors discovered through research that the poor air stability of the sulfide solid electrolyte shell used in patent CN117199511A may be due to the fact that the sulfide solid electrolyte shell in patent CN117199511A contains both S and Li in its structural formula, making it highly chemically reactive with moisture in the air and easily hydrolyzed to produce hydrogen sulfide, thereby deactivating it. Therefore, in this application, the inventors used a lithium-free metal sulfide to coat the inorganic solid electrolyte, which can make the modified inorganic solid electrolyte have relatively ideal air stability.

[0043] The modified solid electrolyte and its preparation method, and the all-solid-state lithium-ion battery of the embodiments of the present application are described in detail below.

[0044] In a first aspect, an embodiment of the present application provides a modified solid electrolyte, which has a core-shell structure, wherein the core is made of an inorganic solid electrolyte and the shell is made of a lithium-free metal sulfide.

[0045] In the present application, the surface of the inorganic solid electrolyte core material has a shell layer of a lithium-free metal sulfide material. Compared with inorganic solid electrolytes, lithium-free metal sulfides have more ideal air stability. The inorganic solid electrolyte is coated with a lithium-free metal sulfide. On the one hand, the air stability of the inorganic solid electrolyte can be effectively improved and the coated solid electrolyte still has a relatively ideal ionic conductivity. On the other hand, the coating and isolation of the inorganic solid electrolyte by the lithium-free metal sulfide can also improve the problem of side reactions that are prone to occur after the inorganic solid electrolyte is in direct contact with the active material (specifically, the sulfide solid electrolyte is very likely to have harmful interfacial side reactions after direct contact with the active material, especially the high-voltage positive electrode and the lithium metal negative electrode; the halide solid electrolyte is easily reduced to form a metal-containing element after direct contact with the lithium metal, and is easily redox reacted during the charge and discharge process after direct contact with the high-voltage positive electrode, resulting in the destruction of the structural integrity of the positive electrode), thereby making the corresponding all-solid-state lithium-ion battery have relatively excellent cycle performance.

[0046] As an example, the metal sulfide is selected from at least one of FeS, CuS and Ag2S.

[0047] In this embodiment, the inorganic solid electrolyte is coated with the above-mentioned type of metal sulfide, which can more effectively improve the air stability of the inorganic solid electrolyte, so that the corresponding all-solid-state lithium-ion battery has better cycle performance.

[0048] As an example, the thickness of the shell is 0.1nm to 1000nm, for example but not limited to a thickness of at least one of 0.1nm, 0.5nm, 1nm, 5nm, 10nm, 50nm, 100nm, 200nm, 400nm, 800nm ​​and 1000nm or a range value between any two of them.

[0049] In this embodiment, limiting the thickness of the outer shell to the above range can better balance the air stability and ionic conductivity of the modified solid electrolyte.

[0050] As an example, the thickness of the shell is 0.5 to 10 nm, for example, but not limited to, a thickness of at least one of 0.5 nm, 0.8 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm and 10 nm, or a range value between any two of the values.

[0051] In this embodiment, the thickness of the shell is limited to the range of 0.5 to 10 nm, which can better balance the air stability and ionic conductivity of the modified solid electrolyte.

[0052] As an example, the inorganic solid electrolyte is selected from at least one of a sulfide solid electrolyte and a halide solid electrolyte.

[0053] In this embodiment, the coating layer provided in the embodiment of the present application can be well adapted to the sulfide solid electrolyte and the halide solid electrolyte.

[0054] It should be noted that the types of sulfide solid electrolytes and halide solid electrolytes are not limited and can be set according to conventional selection in the field. For example, the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 , at least one of Li6PS5Br, Li6PS5I and Li6PS5Cl; for example, the halide solid electrolyte is selected from at least one of Li3InCl6, Li3ScCl6, Li2ZrCl6 and Li3YCl6.

[0055] As an example, the inorganic solid electrolyte is a sulfide solid electrolyte, and the material of the sulfide solid electrolyte is Li6PS5Cl; or / and, the inorganic solid electrolyte is a halide solid electrolyte, and the material of the halide solid electrolyte is Li3InCl6.

[0056] In this embodiment, the coating layer provided in the embodiment of the present application can be well adapted to Li6PS5Cl and Li3InCl6.

[0057] It should be noted that any structural or functional units not specifically described or limited in the modified solid electrolyte may be arranged according to conventional selections in the art.

[0058] In a second aspect, an embodiment of the present application provides a method for preparing a modified solid electrolyte as provided in the embodiment of the first aspect, using atomic layer deposition technology to generate lithium-free metal sulfide on the surface of an inorganic solid electrolyte to form a modified solid electrolyte with a core-shell structure.

[0059] In the present application, atomic layer deposition technology is used to form a lithium-free metal sulfide shell on the surface of an inorganic solid electrolyte, so that the prepared shell has advantages such as relatively uniform thickness, high density and high coverage of the core.

[0060] As an example, the steps of using atomic layer deposition technology to generate lithium-free metal sulfide on the surface of an inorganic solid electrolyte to form a modified solid electrolyte with a core-shell structure include:

[0061] S1 places an inorganic solid electrolyte in a reaction chamber of an atomic layer deposition device, wherein the reaction chamber is in a vacuum state and the temperature is maintained at 50-400°C (for example, but not limited to, a temperature of at least one of 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C and 400°C, or a range value between any two of them); S2 transports a gaseous metal compound into the reaction chamber for sealing treatment so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S3 uses an inert gas to purge the reaction chamber to remove the gaseous metal compound remaining in the reaction chamber; S4 transports a gaseous sulfur source into the reaction chamber so that the gaseous sulfur source and the precursor layer react to generate metal sulfide; S5 uses an inert gas to purge the reaction chamber to remove the gaseous sulfur source remaining in the reaction chamber; S6 repeats steps S2-S5 multiple times to form a modified solid electrolyte with a core-shell structure.

[0062] It should be noted that in step S1, the vacuum degree in the reaction chamber can be set according to conventional selections in the art, for example, the vacuum degree can be (1 to 10)×10 -5 mTorr, for example but not limited to, the vacuum degree can be 1×10 -5 mTorr, 2×10 -5 mTorr, 4×10 -5 mTorr, 6×10 -5 mTorr, 8×10 -5 mTorr and 10×10-5 A range of values ​​between at least one or any two of mTorr.

[0063] In this embodiment, the preparation is carried out according to the above process, and a lithium-free metal sulfide shell layer with relatively uniform thickness, high density and high coverage of the core can be formed on the surface of the inorganic solid electrolyte core; wherein the temperature of the reaction chamber is maintained within the above range so that the gaseous metal compound always remains in a gaseous state before being loaded onto the core, thereby facilitating the gasified metal compound to be more fully loaded onto the surface of the inorganic solid electrolyte to form a precursor layer.

[0064] It should be noted that at the beginning of the first cycle, since there is no coating layer on the surface of the inorganic solid electrolyte core, the formed precursor layer is directly coated on the surface of the inorganic solid electrolyte core. However, after the first cycle, the surface of the inorganic solid electrolyte core already has a metal sulfide shell. Therefore, starting from the second cycle, the formed precursor layer will be coated on the surface of the metal sulfide formed in the previous cycle. By repeating this cycle, a metal sulfide shell of the target thickness is finally prepared.

[0065] As an example, steps S2 to S5 are repeated 10 to 50 times, for example but not limited to, the number of times is at least one of 10 times, 20 times, 30 times, 40 times and 50 times, or a range value between any two of them.

[0066] In this embodiment, steps S2 to S5 are repeated 10 to 50 times so that the prepared shell has a relatively suitable thickness, and thus the prepared modified solid electrolyte can have relatively ideal air stability and ionic conductivity.

[0067] As an example, the step of purging the reaction chamber with an inert gas to remove residual gaseous metal compounds in the reaction chamber includes:

[0068] S31 delivers an inert gas into a reaction chamber in a vacuum state, wherein the pulse gas pressure of the delivered inert gas is 8000-9000 mTorr (for example, but not limited to, the pulse gas pressure is at least one of or a range between any two of 8000 mTorr, 8100 mTorr, 8200 mTorr, 8300 mTorr, 8400 mTorr, 8500 mTorr, 8600 mTorr, 8700 mTorr, 8800 mTorr, 8900 mTorr, and 9000 mTorr); S32 vacuums the reaction chamber to remove the inert gas in the reaction chamber; S33 repeats steps S31-S32 multiple times.

[0069] It should be noted that in step S31, if the reaction chamber is already in a vacuum state, there is no need to perform vacuuming in advance; if the reaction chamber is not in a vacuum state, it is necessary to perform vacuuming in advance, and the specific process can be adaptively adjusted according to actual conditions.

[0070] It should be noted that, in the step of vacuuming, the vacuum degree in the reaction chamber is maintained consistent with the vacuum degree in step S1.

[0071] In this embodiment, by repeatedly purging the reaction chamber with an inert atmosphere and limiting the pulse pressure of the inert gas delivered each time to within the above range, the gaseous metal compounds remaining in the reaction chamber and some gaseous impurities that may be generated can be effectively removed.

[0072] As an example, steps S31 to S33 are repeated 3 to 5 times.

[0073] In this embodiment, steps S31 to S32 are repeated 3 to 5 times, which can more thoroughly remove the gaseous metal compounds remaining in the reaction chamber.

[0074] It should be noted that step S5 can be performed with reference to step S3.

[0075] As an example, the step of transporting the gaseous metal compound into the reaction chamber for sealing treatment so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer includes: S21 transporting the gaseous metal compound into the reaction chamber for sealing treatment, wherein the pulse gas pressure for transporting the gaseous metal compound is 200-400mTorr (for example, but not limited to the pulse gas pressure is at least one of 200mTorr, 250mTorr, 300mTorr, 350mTorr and 400mTorr or a range value between any two), and the sealing treatment time is 0.5-2min (for example, but not limited to the time is at least one of 0.5min, 1min, 1.5min and 2min or a range value between any two), so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S22 using an inert gas to purge the reaction chamber to remove the residual gaseous metal compound in the reaction chamber; S23 repeating steps S21-S22 multiple times.

[0076] In this embodiment, a precursor layer is formed on the surface of the inorganic solid electrolyte by repeated deposition, and in each deposition process, the pulse gas pressure for delivering the gaseous metal compound and the time of the sealing treatment are limited within the above-mentioned ranges, so that the gaseous metal compound can cover the entire surface of the inner core more saturatedly, thereby allowing the outer shell formed by the subsequent reaction to cover the entire inner core more completely and evenly.

[0077] As an example, steps S21 to S22 are repeated 4 to 6 times.

[0078] In this embodiment, steps S21 to S22 are repeated 4 to 6 times, which can better balance the coating integrity, uniformity and coating efficiency of the gaseous metal compound on the core surface.

[0079] As an example, in step S22, the step of purging the reaction chamber with an inert gas includes: first evacuating the reaction chamber, then delivering an inert gas into the reaction chamber, and then evacuating the reaction chamber again, wherein the pulse gas pressure of the delivered inert gas is 8000-9000 mTorr, for example, but not limited to, the pulse gas pressure is at least one of 8000 mTorr, 8100 mTorr, 8200 mTorr, 8300 mTorr, 8400 mTorr, 8500 mTorr, 8600 mTorr, 8700 mTorr, 8800 mTorr, 8900 mTorr and 9000 mTorr, or a range value between any two thereof; in the step of evacuating the reaction chamber, the vacuum level in the reaction chamber is consistent with the vacuum level in step S1.

[0080] It should be noted that the number of times step 22 is performed is not limited. For example, it can be performed only once or repeatedly for multiple times. The specific number of times can be adaptively adjusted according to actual conditions.

[0081] As an example, the step of delivering a gaseous sulfur source into a reaction chamber so that the gaseous sulfur source reacts with the precursor layer to generate metal sulfide includes:

[0082] In step S41, a gaseous sulfur source is transported into a reaction chamber for a sealed treatment, wherein a pulse gas pressure for transporting the gaseous metal compound is 200 to 400 mTorr (for example, but not limited to, a pulse gas pressure of at least one of 200 mTorr, 250 mTorr, 300 mTorr, 350 mTorr, and 400 mTorr, or a range value between any two thereof), and a reaction time is 0.5 to 2 min (for example, but not limited to, a reaction time of at least one of 0.5 min, 1 min, 1.5 min, and 2 min, or a range value between any two thereof), so that the gaseous sulfur source reacts with the precursor layer to generate metal sulfide; in step S42, the reaction chamber is purged with an inert gas to remove residual gaseous sulfur source in the reaction chamber; and in step S43, steps S41 to S42 are repeated multiple times.

[0083] In this embodiment, during the process of the gaseous sulfur source and the precursor layer reacting to generate metal sulfide, the gaseous sulfur source is repeatedly delivered to the reaction chamber, and the pulse gas pressure and reaction time of each delivery of the gaseous sulfur source are respectively limited within the above-mentioned ranges, so that the precursor layer can fully contact and react with the gaseous sulfur source, thereby allowing the shell formed by the reaction to relatively completely and evenly cover the entire core.

[0084] As an example, steps S41 to S42 are repeated 4 to 6 times.

[0085] In this embodiment, steps S41 to S42 are repeated 4 to 6 times to allow the precursor layer and the gaseous sulfur source to contact and react more fully.

[0086] It should be noted that step S42 can be performed with reference to step S22.

[0087] As an example, the material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t BuAMD)2, Fe(acac)3, Ag(fod)(PEt3), [Cu( i PrAMD)]2 and at least one of Cu(acac)2.

[0088] In this embodiment, there are many types of gaseous metal compounds that are applicable to the embodiments of the present application, and more feasible implementation plans can be provided, thereby facilitating the promotion and application of the technical solutions provided by the embodiments of the present application.

[0089] As an example, the material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t At least one of BuAMD)2, Fe(acac)3.

[0090] In this embodiment, the above-mentioned iron-containing gaseous metal compound is used, which forms a metal sulfide shell, which more significantly improves the air stability of the inorganic solid electrolyte. Correspondingly, the corresponding all-solid-state lithium-ion battery has better cycle performance.

[0091] As an example, the material of the gaseous sulfur source is selected from at least one of dimethyl sulfide and hydrogen sulfide.

[0092] In this embodiment, the aforementioned type of gaseous sulfur source can react with the metal compound to form metal sulfide relatively easily and efficiently, and also has the advantages of being safe, portable, and environmentally friendly.

[0093] It should be noted that the gaseous sulfur source can be a single type of gas or a mixed gas mixed with an inert gas. When the gaseous sulfur source is a mixed gas (for example, the gaseous sulfur source is a mixed gas of hydrogen sulfide and nitrogen, wherein the volume proportion of hydrogen sulfide is 50%), the pulse gas pressure when transporting the gaseous sulfur source is the partial pressure of hydrogen sulfide. Specifically, if the pulse gas pressure for transporting the gaseous metal compound is set to 200 mTorr (partial pressure of hydrogen sulfide), the mixed gas should be transported at 400 mTorr.

[0094] It should be noted that any process or step not specifically described or limited in the preparation of the modified solid electrolyte may be configured according to conventional methods in the art.

[0095] As an example, the process flow chart of the preparation method of the modified solid electrolyte is shown in FIG. Figure 1 .

[0096] In a third aspect, an embodiment of the present application provides an all-solid-state lithium-ion battery, which includes a positive electrode sheet, a solid electrolyte membrane and a negative electrode sheet, and the solid electrolyte membrane is located between the positive electrode sheet and the negative electrode sheet; wherein, at least one of the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet includes the modified solid electrolyte provided in the embodiment of the first aspect.

[0097] In the present application, the functional unit (at least one of the positive electrode sheet, solid electrolyte membrane and negative electrode sheet) in the all-solid-state lithium-ion battery includes the modified solid electrolyte provided in the first embodiment. Since the modified solid electrolyte has relatively ideal air stability and relatively suitable ionic conductivity, the corresponding all-solid-state battery has relatively excellent cycle performance.

[0098] It should be noted that each functional unit in the all-solid-state lithium-ion battery can be configured according to conventional selections in the art and is not specifically limited in the embodiments of the present application.

[0099] As an example, the positive electrode sheet includes NCM622 (positive electrode active material), super-P (conductive agent), CNT (conductive agent), Li6PS5Cl (sulfide solid electrolyte) and PVDF (binder) in a mass ratio of 87:1.5:0.3:10:1.2; the negative electrode sheet includes graphite (negative electrode active material), conductive carbon black (conductive agent), Li6PS5Cl (sulfide solid electrolyte) carboxymethyl cellulose, sodium cellulose (binder) and styrene-butadiene rubber (binder) in a mass ratio of 85.6:2:10:1.2:2.2.

[0100] In other possible implementations, Li6PS5Cl (sulfide solid electrolyte) can be completely replaced with Li3InCl6 (halide solid electrolyte); similarly, the types and amounts of other functional components in the positive and negative electrodes can also be adaptively adjusted.

[0101] It should be noted that the solid electrolytes of the positive electrode sheet and the negative electrode sheet can be either one of them using the modified solid electrolyte provided in the embodiment of the present application, or both of them using the modified solid electrolyte provided in the embodiment of the present application, and specific adaptive adjustments can be made according to actual needs.

[0102] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0103] Example 1

[0104] The present invention provides a method for preparing an all-solid-state lithium-ion battery, comprising the following steps:

[0105] (1) Preparation of modified solid electrolyte

[0106] S1 placed 1 kg of Li6PS5Cl in the reaction chamber of the atomic layer deposition equipment, where the reaction chamber was in a vacuum state (vacuum degree of 7.5×10 -5 mTorr) and the temperature was maintained at 180°C.

[0107] S2 transports gaseous ferrocene (Fe(C5H5)2) into the reaction chamber for sealing treatment, so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer. Specifically, the pulse pressure of the gaseous ferrocene is 300mTorr, and the sealing treatment is 1 minute after transportation. This standard is repeated 5 times; and after each time, the reaction chamber needs to be purged once with an inert gas to remove the residual gaseous ferrocene that has not been adsorbed. The standard is: first vacuum the reaction chamber, then transport an inert gas (nitrogen) into the reaction chamber, and then vacuum the reaction chamber again, wherein the pulse pressure of the inert gas is 8500mTorr, and in the vacuum treatment step, the vacuum degree in the reaction chamber is consistent with the vacuum degree in step S1.

[0108] In step S3, the reaction chamber is purged with an inert gas to remove residual gaseous ferrocene in the reaction chamber. Specifically, nitrogen gas is delivered into the vacuum reaction chamber at a pulsed gas pressure of 8500 mTorr, and then the reaction chamber is evacuated until the vacuum level in the reaction chamber is consistent with the vacuum level in step S1. This process is repeated three times according to this standard.

[0109] S4 transports gaseous hydrogen sulfide into the reaction chamber to react with the precursor layer to generate metal sulfide. Specifically, the pulse pressure of the gaseous hydrogen sulfide is 300mTorr, and the reaction is sealed for 1 minute after transporting. This standard is repeated 5 times. Moreover, after each treatment, the reaction chamber needs to be purged with an inert gas once to remove the unreacted residual gaseous hydrogen sulfide. The standard is: first, the reaction chamber is vacuumed, and then an inert gas (nitrogen) is transported into the reaction chamber, and then the reaction chamber is vacuumed again. Among them, the pulse pressure of the inert gas is 8500mTorr. In the vacuum treatment step, the vacuum degree in the reaction chamber is consistent with the vacuum degree in step S1.

[0110] In step S5, the reaction chamber is purged with an inert gas to remove residual gaseous hydrogen sulfide in the reaction chamber. Specifically, nitrogen is delivered into the vacuum reaction chamber at a pulsed gas pressure of 8500 mTorr, and then the reaction chamber is evacuated until the vacuum level in the reaction chamber is consistent with the vacuum level in step S1. This process is repeated three times according to this standard.

[0111] S6: Repeat steps S2 to S5 18 times to form a modified solid electrolyte with a core-shell structure, wherein the shell thickness is 1.01 nm.

[0112] (2) Preparation of all-solid-state lithium-ion batteries

[0113] Preparation of positive electrode sheet: NCM622 (positive electrode active material), super-P (conductive agent), CNT (conductive agent), the coated sulfide solid electrolyte prepared in step (1) and PVDF (binder) are stirred and mixed with N-methylpyrrolidone (NMP) in a vacuum mixer in a mass ratio of 87:1.5:0.3:10:1.2 to obtain a positive electrode sheet slurry; the positive electrode sheet slurry is evenly coated on both sides of an aluminum foil (thickness 13 μm) current collector, and the positive electrode sheet is obtained after drying, cold pressing, and die-cutting.

[0114] Preparation of negative electrode sheet: Graphite (negative electrode active material), conductive carbon black (conductive agent), Li6PS5Cl (uncoated sulfide solid electrolyte), carboxymethyl cellulose, sodium cellulose (binder) and styrene-butadiene rubber (binder) are mixed evenly with deionized water in a vacuum mixer in a mass ratio of 85.6:2:10:1.2:2.2 to obtain negative electrode sheet slurry; the negative electrode sheet slurry is evenly coated on both sides of the copper foil (thickness 8μm) current collector, and the negative electrode sheet is obtained after drying, cold pressing and die-cutting.

[0115] A 20μm thick sulfide solid electrolyte membrane (Li6PS5Cl) was placed between the positive and negative electrodes, and a bare cell was prepared by lamination. A packaging bag was made of an aluminum-plastic film composite material, and the bare cell was placed in the packaging bag and packaged to obtain a dry cell. The dry cell was baked to remove water to reduce the water content to less than 250ppm. Then, the dry cell was subjected to isostatic pressing, sealing, standing, formation, degassing packaging, and capacity division to obtain a soft-pack all-solid-state lithium-ion battery.

[0116] Example 2

[0117] The embodiment of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 1 only in that: all gaseous ferrocene is replaced by gaseous Ag(fod)(PEt3), that is, the material of the formed metal sulfide is replaced by FeS to AgS to form a modified solid electrolyte with a core-shell structure, and the corresponding shell thickness is 0.93 nm.

[0118] Example 3

[0119] The present embodiment provides a method for preparing an all-solid-state lithium-ion battery, which differs from the embodiment 1 only in that the gaseous ferrocene is completely replaced by gaseous Fe( t BuAMD)2, that is, the material of the formed metal sulfide is still FeS, only the raw materials are different, to form a modified solid electrolyte with a core-shell structure, and the corresponding shell thickness is 1.12nm.

[0120] Comparative Example 1

[0121] The comparative example of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 1 only in that: in step (1), no coating layer is formed on the surface of Li6PS5Cl, that is, there is no metal sulfide shell on the surface of Li6PS5Cl in the positive electrode sheet.

[0122] The comparative example of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 1 only in that:

[0123] Example 4

[0124] This embodiment of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 1 only in that:

[0125] In step (1), all 1 kg of Li6PS5Cl is replaced with Li3InCl6, that is, the sulfide solid electrolyte core is replaced with a halide solid electrolyte core to form a modified solid electrolyte with a core-shell structure, wherein the shell thickness is 1.04 nm.

[0126] In step (ii), NCM622 (positive electrode active material), super-P (conductive agent), CNT (conductive agent), Li3InCl6 (uncoated halide solid electrolyte) and PVDF (binder) are stirred and mixed with N-methylpyrrolidone (NMP) in a vacuum mixer in a mass ratio of 87:1.5:0.3:10:1.2 to obtain a positive electrode slurry; graphite (negative electrode active material), conductive carbon black (conductive agent), the coated halide solid electrolyte prepared in step (i), carboxymethyl cellulose, sodium cellulose (binder) and styrene-butadiene rubber (binder) are stirred and mixed with deionized water in a vacuum mixer in a mass ratio of 85.6:2:10:1.2:2.2 to obtain a negative electrode slurry.

[0127] In step (2), the material used for the solid electrolyte membrane is replaced by Li6PS5Cl to Li3InCl6.

[0128] Example 5

[0129] The embodiment of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 4 only in that: all gaseous ferrocene is replaced by gaseous Ag(fod)(PEt3), that is, the material of the formed metal sulfide is replaced by FeS to AgS to form a modified solid electrolyte with a core-shell structure, wherein the shell thickness is 0.96 nm.

[0130] Example 6

[0131] The present embodiment provides a method for preparing an all-solid-state lithium-ion battery, which differs from the embodiment 4 only in that the gaseous ferrocene is completely replaced by gaseous Fe( t BuAMD)2, that is, the material of the formed metal sulfide is still FeS, only the preparation raw materials are different, to form a modified solid electrolyte with a core-shell structure, wherein the shell thickness is 1.08nm.

[0132] Comparative Example 2

[0133] The comparative example of the present application provides a method for preparing an all-solid-state lithium-ion battery, which differs from Example 4 only in that: in step (1), no coating layer is formed on the surface of Li3InCl6, that is, there is no metal sulfide shell on the surface of Li3InCl6 in the negative electrode sheet.

[0134] Test example

[0135] 1. Air stability test of solid electrolyte

[0136] Examples 1 to 3 and Comparative Example 1, Examples 4 to 6 and Comparative Example 2 were divided into two groups according to the solid electrolyte material, and then the air stability of the solid electrolyte samples prepared in step (1) was tested respectively, and the test results were statistically summarized in Table 1.

[0137] The test steps for air stability are as follows:

[0138] The lithium ion conductivity of the solid electrolyte powder was tested before and after being exposed to moisture at a relative humidity of 5% for 24 hours, and the retention rate of the lithium ion conductivity was calculated.

[0139] Table 1

[0140]

[0141]

[0142] It should be noted that in Table 1, the ionic conductivity retention rate of Comparative Example 1 and Comparative Example 2 is 0. This is because there is no coating layer on the internal surface of the solid electrolyte, and the reaction activity of the material is high, resulting in severe decomposition of the material after exposure to moisture with a relative humidity of 5% for 24 hours.

[0143] It should be noted that in Table 1, compared with Example 1 and Example 3, and compared with Example 4 and Example 6, the ion retention rate of the former is higher. The reasons may be: (1) different raw materials and different impurity components that may be generated during the preparation process; (2) the physical and chemical properties such as the density of the formed shell may be different.

[0144] Referring to Table 1, the test results of Examples 1-3 and Comparative Example 1, and Examples 4-6 and Comparative Example 2 show that the provision of a lithium-free metal sulfide shell around the inorganic solid electrolyte core results in more stable lithium ion conductivity in air compared to the absence of a shell, i.e., superior air stability.

[0145] 2. Cycle performance test of all-solid-state lithium-ion batteries

[0146] Examples 1 to 3 and Comparative Example 1, Examples 4 to 6 and Comparative Example 2 were divided into two groups according to the solid electrolyte material, and then the cycle performance of each battery sample in the two groups was tested respectively, and the test results were statistically summarized in Table 2.

[0147] Among them, the test parameters of the battery cycle performance are as follows: the obtained all-solid-state lithium-ion battery is subjected to a charge and discharge cycle test, with a charging current of 0.8A, a cut-off voltage of 4.9V, a discharge current of 0.8A, a cut-off voltage of 2.5V, and a test environment temperature of 25°C. The number of cycles when the battery capacity decays to 80% is counted.

[0148] Table 2

[0149]

[0150]

[0151] It should be noted that the cycle performance of Example 2 is poor compared with that of Example 1, and that of Example 5 is poor compared with that of Example 4, which may be caused by the different materials of the shell. Specifically, when the shell material is FeS, the cycle performance of the corresponding battery is better.

[0152] Referring to Table 2, the test results of Examples 1-3 and Comparative Example 1, and Examples 4-6 and Comparative Example 2 show that the provision of a lithium-free metal sulfide shell around the inorganic solid electrolyte core results in an all-solid-state lithium-ion battery with superior cycling performance compared to batteries without the shell.

[0153] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A modified solid electrolyte, characterized in that The modified solid electrolyte is a core-shell structure, wherein the core is made of an inorganic solid electrolyte and the shell is made of a lithium-free metal sulfide.

2. The modified solid electrolyte according to claim 1, characterized in that The metal sulfide is selected from at least one of FeS, CuS and Ag2S.

3. The modified solid electrolyte according to claim 2, characterized in that The thickness of the shell is 0.1nm to 1000nm; Optionally, the shell has a thickness of 0.5 to 10 nm.

4. The modified solid electrolyte according to any one of claims 1 to 3, characterized in that The inorganic solid electrolyte is selected from at least one of a sulfide solid electrolyte and a halide solid electrolyte.

5. The modified solid electrolyte according to claim 4, characterized in that The inorganic solid electrolyte is a sulfide solid electrolyte, and the material of the sulfide solid electrolyte is Li6PS5Cl; Or / and, the inorganic solid electrolyte is a halide solid electrolyte, and the material of the halide solid electrolyte is Li3InCl6.

6. A method for preparing a modified solid electrolyte according to any one of claims 1 to 5, characterized in that: Atomic layer deposition technology is used to generate lithium-free metal sulfide on the surface of an inorganic solid electrolyte to form the modified solid electrolyte with a core-shell structure.

7. The preparation method according to claim 6, characterized in that The step of using atomic layer deposition technology to generate lithium-free metal sulfide on the surface of the inorganic solid electrolyte to form the modified solid electrolyte with a core-shell structure includes: S1: placing an inorganic solid electrolyte in a reaction chamber of an atomic layer deposition device, wherein the reaction chamber is in a vacuum state and the temperature is maintained at 50-400° C.; S2: transporting the gaseous metal compound into the reaction chamber for sealing treatment, so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S3: purging the reaction chamber with an inert gas to remove the gaseous metal compound remaining in the reaction chamber; S4: delivering a gaseous sulfur source into the reaction chamber so that the gaseous sulfur source reacts with the precursor layer to generate the metal sulfide; S5: purging the reaction chamber with an inert gas to remove the gaseous sulfur source remaining in the reaction chamber; S6: repeating steps S2 to S5 multiple times to form the modified solid electrolyte having a core-shell structure; Optionally, steps S2 to S5 are repeated 10 to 50 times.

8. The preparation method according to claim 7, characterized in that The step of transporting the gaseous metal compound into the reaction chamber for sealing treatment so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer includes: S21: transporting the gaseous metal compound into the reaction chamber for sealing treatment, wherein the pulse gas pressure of the gaseous metal compound is 200-400 mTorr and the sealing treatment time is 0.5-2 minutes, so that the gaseous metal compound is adsorbed on the surface of the inorganic solid electrolyte to form a precursor layer; S22: purging the reaction chamber with an inert gas to remove the gaseous metal compound remaining in the reaction chamber; S23 repeats steps S21 to S22 multiple times; Optionally, steps S21 to S22 are repeated 4 to 6 times.

9. The preparation method according to claim 7, characterized in that The step of purging the reaction chamber with an inert gas to remove the gaseous metal compound remaining in the reaction chamber includes: S31: supplying an inert gas into the reaction chamber in a vacuum state, wherein the pulse gas pressure of the inert gas is 8000-9000 mTorr; S32: performing a vacuum process on the reaction chamber to remove the inert gas in the reaction chamber; S33 repeats steps S31 to S32 multiple times; Optionally, steps S31 to S33 are repeated 3 to 5 times.

10. The preparation method according to claim 7, characterized in that The step of transporting a gaseous sulfur source into the reaction chamber so that the gaseous sulfur source reacts with the precursor layer to generate the metal sulfide comprises: S41: delivering a gaseous sulfur source into the reaction chamber for sealing treatment, wherein the pulse gas pressure of delivering the gaseous metal compound is 200-400 mTorr and the reaction time is 0.5-2 min, so that the gaseous sulfur source reacts with the precursor layer to generate the metal sulfide; S42: purging the reaction chamber with an inert gas to remove the gaseous sulfur source remaining in the reaction chamber; S43 repeats steps S41 to S42 multiple times; Optionally, steps S41 to S42 are repeated 4 to 6 times.

11. The preparation method according to any one of claims 7 to 10, characterized in that The material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t BuAMD)2, Fe(acac)3, Ag(fod)(PEt3), [Cu( i At least one of PrAMD)]2 and Cu(acac)2; Optionally, the material of the gaseous metal compound is selected from Fe(C5H5)2, Fe( t At least one of BuAMD)2, Fe(acac)3.

12. The preparation method according to any one of claims 7 to 10, characterized in that The material of the gaseous sulfur source is selected from at least one of dimethyl sulfide and hydrogen sulfide.

13. An all-solid-state lithium-ion battery, characterized in that: The all-solid-state lithium-ion battery comprises a positive electrode sheet, a solid electrolyte membrane and a negative electrode sheet, wherein the solid electrolyte membrane is located between the positive electrode sheet and the negative electrode sheet; Wherein, at least one of the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet comprises the modified solid electrolyte according to any one of claims 1 to 5.

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