Preparation method of ceramic-based solid electrolyte with low interface impedance and preparation method of solid-state battery

Abstract

The invention discloses a preparation method of a low-interface-impedance ceramic-based solid electrolyte and a solid-state battery. The preparation method comprises the following steps: polishing a ceramic wafer, bombarding by plasma, depositing a magnesium layer, preparing a negative plate, preparing a positive plate and assembling and hot-pressing the battery. The magnesium metal layer is deposited on the surface of the ceramic chip, magnesium metal not only has lithium affinity, but also has relatively high lithium ion conductivity, so that the conductivity of the solid electrolyte is effectively improved, and the magnesium metal has relatively high plasticity and hot pressing at a high temperature, so that the contact of the negative electrode plate and the solid electrolyte is more sufficient and compact; and the polymer sheet is added between the positive plate and the solid electrolyte during battery assembly, so that the contact between the positive plate and the solid electrolyte is tighter and more compact in the subsequent hot pressing process, the interface impedance is further reduced, and the electrochemical performance of the battery is further effectively improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a ceramic-based solid electrolyte with low interfacial impedance and a method for preparing a solid-state battery. Background Technology

[0002] In recent years, with the rapid development of new energy technologies, batteries, as important energy storage media and power sources for portable electronic devices, have played an increasingly crucial role in the industrial field. Among them, lithium-ion batteries, with their superior energy density and power density, have become the most ideal portable power solution. However, traditional liquid lithium-ion batteries pose significant safety risks due to the presence of large amounts of flammable organic electrolytes. To fundamentally solve this problem, all-solid-state lithium batteries are becoming the forefront of global battery technology research and development, and a key path to overcome the current energy density bottleneck and thermal runaway risk of liquid lithium-ion batteries.

[0003] Among the various solid-state battery technologies, using inorganic ceramic materials as electrolytes to replace traditional liquid electrolytes is one of the most promising directions. However, ceramic-based solid-state batteries face a key challenge: achieving sufficiently dense contact between the electrode and electrolyte layer is difficult. These ineffectively contacted interfaces form high-resistance regions, severely limiting the overall electrochemical performance of the battery. Therefore, it is necessary to propose a new approach to improve upon this problem. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a method for preparing a ceramic-based solid electrolyte and a solid battery with low interfacial impedance. This method can effectively solve the problem that existing solid batteries cannot achieve sufficient and dense contact between the electrode and electrolyte layer, thus forming a high-impedance region that severely restricts the overall electrochemical performance of the battery.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a ceramic-based solid electrolyte with low interfacial impedance includes the following steps:

[0007] (1) Polish the ceramic sheet to remove impurities from the surface of the ceramic sheet, then put it into deionized water for ultrasonic cleaning, and dry it to obtain the cleaned ceramic sheet.

[0008] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce inert gas and apply plasma to bombard the substrate surface for 1-10 minutes to obtain the treated ceramic sheet.

[0009] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -5 -5.0×10 -3 Pa, inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 0.1-5.0 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 60-120 min and 25-300 °C. After deposition, the temperature is raised to 100-300 °C and annealed for 0.5-2 h. Finally, it is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance.

[0010] As a preferred embodiment, the thickness of the ceramic sheet in step (1) is 0.3-1 mm.

[0011] As a preferred option, the ceramic sheet in step (1) is made of LLZTO material.

[0012] As a preferred embodiment, the purity of the magnesium target in step (2) is ≥99.9%.

[0013] As a preferred embodiment, the inert gas in steps (2) and (3) is argon, and the purity of the argon is ≥99.999%.

[0014] A method for preparing a solid-state battery includes the following steps:

[0015] (a) Mix the negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder in a mass ratio of 80:18:1:2, add negative electrode solvent, stir evenly to obtain negative electrode slurry, coat the negative electrode slurry evenly on the negative electrode current collector, dry to obtain negative electrode sheet.

[0016] (b) Mix the positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder in a mass ratio of 80:18:1:2, add positive electrode solvent, stir evenly to obtain positive electrode slurry, coat the positive electrode slurry evenly on the positive electrode current collector, dry it to obtain positive electrode sheet.

[0017] (c) The negative electrode sheet obtained in step (a), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (b) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225-250°C at a heating rate of 1-6°C / min for hot pressing at a pressure of 10-20 MPa for 30-90 min. Finally, the tabs are welded and the product is encapsulated in a negative pressure aluminum-plastic film to obtain a solid-state battery.

[0018] As a preferred embodiment, the negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0019] As a preferred embodiment, the positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide coated with LiNbO3, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0020] As a preferred embodiment, the polymer sheet is made of thermoplastic polyamide.

[0021] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0022] By depositing a magnesium layer on the surface of a ceramic sheet, magnesium not only possesses lithium affinity but also exhibits high lithium-ion conductivity, effectively improving the conductivity of the solid electrolyte. Furthermore, magnesium's high plasticity at high temperatures allows for more thorough and denser contact between the negative electrode and the solid electrolyte after hot pressing, effectively reducing interfacial impedance. Additionally, adding a polymer sheet between the positive electrode and the solid electrolyte during battery assembly further enhances the tightness and density of their contact during subsequent hot pressing, further reducing interfacial impedance and thus effectively improving the battery's electrochemical performance.

[0023] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to several specific embodiments. Detailed Implementation

[0024] This invention discloses a method for preparing a ceramic-based solid electrolyte with low interfacial impedance, which includes the following steps:

[0025] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The thickness of the ceramic sheet is 0.3-1mm and the ceramic sheet is made of LLZTO material.

[0026] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce an inert gas and apply plasma to bombard the substrate surface to further activate the substrate surface and improve the film-substrate adhesion. The treatment time is 1-10 min to obtain the treated ceramic sheet. The inert gas is argon and the purity of argon is ≥99.999%.

[0027] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -5 -5.0×10 -3 Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 0.1-5.0 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 60-120 min at a deposition temperature of 25-300 °C. After deposition, the temperature is raised to 100-300 °C and annealed for 0.5-2 h. Finally, the sheet is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity ≥99.999%.

[0028] This invention also discloses a method for preparing a solid-state battery, comprising the following steps:

[0029] (a) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the negative electrode solvent is added, and the mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0030] (b) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The positive electrode solvent is added and stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0031] (c) The negative electrode sheet obtained in step (a), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (b) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225-250°C at a heating rate of 1-6°C / min for hot pressing at a pressure of 10-20 MPa for 30-90 min. Finally, the tabs are welded and the product is encapsulated in a negative pressure aluminum-plastic film to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0032] The following detailed description is based on several embodiments.

[0033] Example 1

[0034] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The ceramic sheet is 0.5 mm thick and is made of LLZTO material.

[0035] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce inert gas and apply plasma to bombard the substrate surface for 1 minute to obtain the treated ceramic sheet; the inert gas is argon and the purity of argon is ≥99.999%.

[0036] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -3Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 0.5 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 100 min at a deposition temperature of 25 °C. After deposition, the temperature is raised to 200 °C and annealed for 2 h. Finally, the temperature is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity ≥99.999%.

[0037] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0038] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0039] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225°C at a heating rate of 1°C / min for hot pressing at a pressure of 10 MPa for 60 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0040] Example 2

[0041] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The ceramic sheet is 1 mm thick and is made of LLZTO material.

[0042] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce an inert gas and apply plasma to bombard the substrate surface for 1-10 minutes to obtain the treated ceramic sheet; the inert gas is argon and the purity of argon is ≥99.999%.

[0043] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -5 Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 2.0 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 60 min at a deposition temperature of 30 °C. After deposition, the temperature is raised to 150 °C and annealed for 0.5 h. Finally, the temperature is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity ≥99.999%.

[0044] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0045] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0046] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 250°C at a heating rate of 1°C / min for hot pressing at a pressure of 18 MPa for 50 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0047] Example 3

[0048] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The ceramic sheet is 0.3 mm thick and is made of LLZTO material.

[0049] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce inert gas and apply plasma to bombard the substrate surface for 8 minutes to obtain the treated ceramic sheet; the inert gas is argon and the purity of argon is ≥99.999%.

[0050] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -4 Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 1.0 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 90 min at a deposition temperature of 200 °C. After deposition, the temperature is raised to 100 °C and annealed for 1 h. Finally, the temperature is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity ≥99.999%.

[0051] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0052] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0053] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 240°C at a heating rate of 3°C / min for hot pressing at a pressure of 12 MPa for 40 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0054] Example 4

[0055] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The thickness of the ceramic sheet is 0.3-1mm and the ceramic sheet is made of LLZTO material.

[0056] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce an inert gas and apply plasma to bombard the substrate surface for 1-10 minutes to obtain the treated ceramic sheet; the inert gas is argon and the purity of argon is ≥99.999%.

[0057] (3) Install the magnesium metal target at the target position in the vapor deposition chamber, and evacuate the chamber to achieve a background vacuum of 4.0 × 10⁻⁶. -4Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 2.5 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 100 min at a deposition temperature of 210 °C. After deposition, the temperature is raised to 190 °C and annealed for 1.5 h. Finally, the temperature is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity of ≥99.999%.

[0058] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0059] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0060] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225°C at a heating rate of 2.5°C / min for hot pressing at a pressure of 15 MPa for 50 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0061] Example 5

[0062] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The ceramic sheet is 0.8 mm thick and is made of LLZTO material.

[0063] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce inert gas and apply plasma to bombard the substrate surface for 3 minutes to obtain the treated ceramic sheet. The inert gas is argon and the purity of argon is ≥99.999%.

[0064] (3) Install the magnesium target in the target position of the vapor deposition chamber and evacuate the chamber to achieve a background vacuum of 8.0 × 10⁻⁶. -4 Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 4 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 110 min at a deposition temperature of 280 °C. After deposition, the temperature is raised to 180 °C and annealed for 1 h. Finally, the temperature is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance. The ceramic-based solid electrolyte with low interfacial impedance has a magnesium deposition layer on one side. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity ≥99.999%.

[0065] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0066] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0067] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 250°C at a heating rate of 1°C / min for hot pressing at a pressure of 20 MPa for 30 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0068] Example 6

[0069] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The ceramic sheet is 0.75mm thick and is made of LLZTO material.

[0070] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce an inert gas and apply plasma to bombard the substrate surface for 1-10 minutes to obtain the treated ceramic sheet; the inert gas is argon and the purity of argon is ≥99.999%.

[0071] (3) Install the magnesium target in the target position of the vapor deposition chamber and evacuate the chamber to achieve a background vacuum of 9.0 × 10⁻⁶. -4 Pa, an inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 3.5 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 70 min at a deposition temperature of 250 °C. After deposition, the temperature is raised to 250 °C and annealed for 1 h. Finally, it is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance. The purity of the magnesium target is ≥99.9%, and the inert gas is argon with a purity of ≥99.999%.

[0072] (4) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The negative electrode solvent is added and stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0073] (5) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0074] (6) The negative electrode sheet obtained in step (4), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (5) are stacked sequentially from top to bottom, with the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte facing upwards, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225°C at a heating rate of 1°C / min for hot pressing at a pressure of 10 MPa for 30 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0075] Comparative Example 1

[0076] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, and then ultrasonically cleaned in deionized water. After drying, the cleaned ceramic sheet is obtained. The thickness of the ceramic sheet is 0.3-1mm and the ceramic sheet is made of LLZTO material.

[0077] (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce an inert gas and apply plasma to bombard the substrate surface to further activate the substrate surface and improve the film-substrate adhesion. The treatment time is 1-10 min to obtain a ceramic-based solid electrolyte. The inert gas is argon, and the purity of argon is ≥99.999%.

[0078] (3) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the negative electrode solvent is added, and the mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0079] (4) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2. The positive electrode solvent is added and stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on the surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0080] (5) The negative electrode sheet obtained in step (3), the aforementioned low interfacial impedance ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (4) are stacked sequentially from top to bottom to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225°C at a heating rate of 2.5°C / min for hot pressing at a pressure of 15 MPa for 50 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0081] Comparative Example 2

[0082] (1) The ceramic sheet is polished to remove impurities from the surface of the ceramic sheet, then placed in deionized water for ultrasonic cleaning, and dried to obtain a ceramic-based solid electrolyte; the thickness of the ceramic sheet is 0.3-1mm, and the ceramic sheet is made of LLZTO material.

[0083] (2) The negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the negative electrode solvent is added, and the mixture is stirred evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector and dried to obtain a negative electrode sheet. The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

[0084] (3) The positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder are mixed evenly in a mass ratio of 80:18:1:2, the positive electrode solvent is added, and the mixture is stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide with LiNbO3 on its surface, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

[0085] (4) The negative electrode sheet obtained in step (2), the aforementioned ceramic-based solid electrolyte, the polymer sheet, and the positive electrode sheet obtained in step (3) are stacked sequentially from top to bottom to obtain a semi-finished product. The semi-finished product is then placed in a hot press, and an inert gas is introduced. The semi-finished product is heated to 225°C at a heating rate of 2.5°C / min for hot pressing at a pressure of 15 MPa for 50 min. Finally, the tabs are welded and the negative pressure aluminum-plastic film is encapsulated sequentially to obtain a solid-state battery. The polymer sheet is made of thermoplastic polyamide.

[0086] Performance tests were conducted on the above embodiments and comparative examples, and the test results are shown in Table 1.

[0087]

[0088] Table 1

[0089] A detailed analysis of the above data was conducted. First, Example 4 was compared with Comparative Examples 1 and 2. The differences among the three are as follows: Comparative Example 1 did not have a deposited magnesium metal layer; Comparative Example 2, while lacking a magnesium metal layer, also did not undergo plasma bombardment; Comparative Example 4 had an internal resistance of 55Ω, a capacity retention rate of 94.0% after 100 cycles at 0.1C, and a capacity retention rate of 89.5% after 100 cycles at 0.5C; while Comparative Example 1 had an internal resistance of 480Ω, a capacity retention rate of 85.0% after 100 cycles at 0.1C, and a capacity retention rate of 79.0% after 100 cycles at 0.5C. Compared to Example 4, the internal resistance of Comparative Example 1 was 8.7 times that of Example 4, and the capacity retention rates after 100 cycles at 0.1C and 0.88 times that of Example 4, respectively. Therefore, even with plasma bombardment, Comparative Example 1... Modifying the ceramic sheet increases the adhesion between its surface and the film layer, resulting in more stable contact between the negative electrode and the solid electrolyte. However, compared to the plasticity of the magnesium metal layer, the magnesium metal layer, after hot pressing, provides a more thorough and denser contact between the negative electrode and the solid electrolyte. Comparative Example 2 exhibits an internal resistance of 1350Ω, a capacity retention of 78.0% after 100 cycles at 0.1C, and a capacity retention of 72.0% after 100 cycles at 0.5C, showing very poor performance, far lower than Comparative Example 1. This is because the adhesion between the simply polished ceramic sheet and the negative electrode is far less than that of the ceramic sheet bombarded by plasma, resulting in insufficient contact between the solid electrolyte and the negative electrode in Comparative Example 2, causing its performance to lag significantly behind Comparative Example 1. In conclusion, the combined effect of plasma bombardment and magnesium metal deposition significantly improves the electrochemical performance of the battery, achieving remarkable progress.

[0090] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a ceramic-based solid electrolyte with low interfacial impedance, characterized in that: It includes the following steps: (1) Polish the ceramic sheet to remove impurities from the surface of the ceramic sheet, then put it into deionized water for ultrasonic cleaning, and dry it to obtain the cleaned ceramic sheet. (2) Place the cleaned ceramic sheet obtained in step (1) into a physical vapor deposition chamber, introduce inert gas and apply plasma to bombard the substrate surface for 1-10 minutes to obtain the treated ceramic sheet. (3) Install the magnesium target in the target position of the vapor deposition chamber and evacuate the chamber to achieve a background vacuum of 5.0 × 10⁻⁶. -5 -5.0×10 -3 Pa, inert gas is introduced and the gas flow rate is adjusted to maintain the gas pressure in the vapor deposition chamber at 0.1-5.0 Pa. Chemical deposition is performed on the ceramic sheet obtained in step (2) for 60-120 min and 25-300 °C. After deposition, the temperature is raised to 100-300 °C and annealed for 0.5-2 h. Finally, it is slowly cooled to room temperature to obtain a ceramic-based solid electrolyte with low interfacial impedance and a magnesium deposition layer on one side of the ceramic-based solid electrolyte with low interfacial impedance.

2. The method for preparing a ceramic-based solid electrolyte with low interfacial impedance according to claim 1, characterized in that: The thickness of the ceramic sheet in step (1) is 0.3-1mm.

3. The method for preparing a ceramic-based solid electrolyte with low interfacial impedance according to claim 1, characterized in that: The ceramic sheet in step (1) is made of LLZTO material.

4. The method for preparing a ceramic-based solid electrolyte with low interfacial impedance according to claim 1, characterized in that: The purity of the magnesium target in step (2) is ≥99.9%.

5. The method for preparing a ceramic-based solid electrolyte with low interfacial impedance according to claim 1, characterized in that: The inert gas used in steps (2) and (3) is argon, and the purity of argon is ≥99.999%.

6. A method for preparing a solid-state battery, characterized in that: It includes the following steps: (a) Mix the negative electrode active material, negative electrode electrolyte, negative electrode conductive agent and negative electrode binder in a mass ratio of 80:18:1:2, add negative electrode solvent, stir evenly to obtain negative electrode slurry, coat the negative electrode slurry evenly on the negative electrode current collector, dry to obtain negative electrode sheet. (b) Mix the positive electrode active material, positive electrode electrolyte, positive electrode conductive agent and positive electrode binder in a mass ratio of 80:18:1:2, add positive electrode solvent, stir evenly to obtain positive electrode slurry, coat the positive electrode slurry evenly on the positive electrode current collector, dry it to obtain positive electrode sheet. (c) The negative electrode sheet obtained in step (a), the low interfacial impedance ceramic-based solid electrolyte as described in any one of claims 1-5, the polymer sheet, and the positive electrode sheet obtained in step (b) are stacked sequentially from top to bottom, wherein the magnesium deposition layer of the low interfacial impedance ceramic-based solid electrolyte faces upward, to obtain a semi-finished product. The semi-finished product is then placed in a hot press, an inert gas is introduced, and the semi-finished product is heated to 225-250°C at a heating rate of 1-6°C / min for hot pressing at a pressure of 10-20 MPa for 30-90 min. Finally, the tabs are welded and the product is encapsulated in a negative pressure aluminum-plastic film to obtain a solid-state battery.

7. The method for preparing a solid-state battery according to claim 6, characterized in that: The negative electrode current collector is copper foil, the negative electrode active material is graphite, the negative electrode electrolyte is Li6PS5C, the negative electrode conductive agent is carbon nanotubes, the negative electrode binder is PAA, and the negative electrode solvent is p-xylene.

8. The method for preparing a solid-state battery according to claim 6, characterized in that: The positive electrode current collector is aluminum foil, the positive electrode active material is lithium nickel cobalt manganese oxide coated with LiNbO3, the lithium nickel cobalt manganese oxide is NCM811, the content of LiNbO3 is 1wt%, the positive electrode electrolyte is Li6PS5C, the positive electrode conductive agent is carbon nanotubes, the positive electrode binder is PAA, and the positive electrode solvent is p-xylene.

9. The method for preparing a solid-state battery according to claim 6, characterized in that: The polymer sheet is made of thermoplastic polyamide.

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