All-solid-state battery and method for preparing same

Abstract

The present invention provides an all-solid-state battery and a preparation method thereof. The preparation method comprises the following steps: (1) spray-wetting a positive electrode sheet or a negative electrode sheet, and then directly spraying a solid electrolyte composite powder onto the surface of the wetted positive electrode sheet or negative electrode sheet, and pressing to obtain a semi-finished battery cell; (2) compounding the other electrode sheet with the semi-finished battery cell obtained in step (1) to obtain the all-solid-state battery; both the positive electrode sheet and the negative electrode sheet are prepared by a wet homogenization coating method. In the present invention, by spray-wetting the electrode sheet and combining with a powder spraying method, using composite electrolyte particles to replace the electrolyte slurry, it not only avoids the problem of serious decline in ionic conductivity due to the over-long soaking time of the electrolyte in the solvent in the wet process, but also can ensure the contact between the electrolyte layer and the electrode layer, reduce the internal impedance of the battery, and improve the reversible capacity and cycle life of the solid-state battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state batteries and relates to an all-solid-state battery and a preparation method thereof. Background Art

[0002] Lithium secondary batteries are widely used in 3C digital, automotive, energy storage and other fields due to their high energy density, wide operating temperature range, and environmental friendliness. The electrode material system used in liquid lithium-ion batteries determines that their energy density will not be too high, and they are increasingly unable to meet the market's demand for higher performance batteries.

[0003] Compared with liquid lithium-ion batteries, all-solid-state batteries use solid electrolytes to replace the organic electrolytes and diaphragms in liquid battery systems, avoiding the risk of thermal runaway caused by short circuits caused by lithium dendrites piercing the diaphragm. At the same time, solid electrolytes do not produce gas under high temperature conditions, eliminating the potential safety hazards of batteries, and are more in line with the future development needs of electric vehicles and large-scale energy storage. By introducing silicon anodes or lithium metal anodes in all-solid-state batteries, the energy density of the battery can be further improved, reducing the "range anxiety" that is common in electric vehicles.

[0004] At present, there are two methods for preparing solid-state batteries: wet method and dry method. The wet method is to stir the active material, conductive agent, electrolyte, binder, and solvent to form a slurry and apply it on the current collector, then apply the electrolyte slurry on the surface of the positive / negative electrode, and stack the sheets to form a full battery. For example, CN111628139A discloses a wet method for preparing all-solid-state battery electrodes. The invention obtains a composite electrolyte suspension by mixing the electrolyte and the solvent, and applies it on the surface of the base electrode to form a solid-state battery electrode with multiple sulfide electrolyte layers in situ, thereby achieving good contact between the electrolyte layer and the electrode material layer. However, a large amount of alcohol substances are used in the preparation process of the electrolyte, which is toxic. And after the electrolyte is soaked in an alcohol solvent for a long time, its ionic conductivity decreases, affecting the electrochemical performance of the solid-state battery. CN111883855A discloses a dry method for preparing all-solid-state batteries. The preparation method comprises the following steps: (1) laminating the negative electrode sheet with the electrolyte membrane and then isostatically pressing to obtain a semi-finished battery cell; (2) laminating the positive electrode sheet on the electrolyte membrane of the semi-finished battery cell and then isostatically pressing to obtain a fully solid-state battery cell. The preparation method belongs to a dry method, in which the electrolyte is prepared into an electrolyte film by mixing and stirring and then isostatically pressing, and then the film is laminated to the electrode sheet, so that the inorganic solid electrolyte layer in the composite electrode and the electrode surface are poorly bonded, and the production process is difficult, which limits its large-scale application.

[0005] Therefore, how to improve the preparation method of all-solid-state batteries, improve the contact between active materials and electrolyte layers, reduce the amount of electrolyte used, and reduce the loss of electrolyte ion conductivity is an urgent problem that needs to be solved. Summary of the invention

[0006] The object of the present invention is to provide an all-solid-state battery and a preparation method thereof. The present invention prepares an all-solid-state battery by a method combining dry and wet processes. The electrolyte layer is formed by semi-dry pressing instead of wet mixing. The electrode sheets are wetted by spraying, and at the same time, powder spraying is combined. Composite electrolyte particles are used to replace the electrolyte slurry, which not only avoids the problem of serious decrease in ionic conductivity due to excessive soaking time of the electrolyte in the solvent during the wet process, but also ensures the contact between the electrolyte layer and the electrode layer, reduces the internal impedance of the battery, and improves the reversible capacity and cycle life of the solid-state battery.

[0007] To achieve the object of the present invention, the following technical solutions are adopted:

[0008] In a first aspect, the present invention provides a preparation method of an all-solid-state battery, and the preparation method includes the following steps:

[0009] (1) Spraying and wetting a positive electrode sheet or a negative electrode sheet, and then directly spraying a solid electrolyte composite powder onto the surface of the wetted positive electrode sheet or negative electrode sheet, and pressing to obtain a semi-finished battery cell;

[0010] (2) Combining the other electrode sheet of the electrode with the semi-finished battery cell in step (1) to obtain the all-solid-state battery;

[0011] Both the positive electrode sheet and the negative electrode sheet are prepared by a wet homogenization coating method.

[0012] The types of electrolytes in the solid electrolyte composite powder provided by the present invention are selected by conventional techniques, including but not limited to sulfide electrolytes, oxide electrolytes, polymer electrolytes, etc.

[0013] The other electrode sheet of the electrode in the present invention specifically means that if the positive electrode sheet is wetted, the other electrode sheet is the negative electrode sheet; if the negative electrode sheet is wetted, the other electrode sheet is the positive electrode sheet.

[0014] The present invention prepares an all-solid-state battery by a method combining dry and wet processes. The electrolyte layer is formed by semi-dry pressing instead of wet mixing. The electrode sheets are wetted by spraying, and at the same time, powder spraying is combined. Composite electrolyte particles are used to replace the electrolyte slurry, which not only avoids the problem of serious decrease in ionic conductivity due to excessive soaking time of the electrolyte in the solvent during the wet process, but also ensures the contact between the electrolyte layer and the electrode layer, reduces the internal impedance of the battery, and improves the reversible capacity and cycle life of the solid-state battery.

[0015] In the present invention, the electrolyte layer is fabricated by semi-dry pressing instead of wet mixing. The electrode plates are wetted by spraying, and composite electrolyte particles are used to replace the electrolyte slurry, reducing the use of organic solvents and the harm of organic substances to the environment and humans. By wetting the electrode plates with solvents, the contact between the electrolyte and the electrode is increased, and the contact impedance between the electrolyte layer and the electrode layer is reduced. By means of powder spraying, the thickness of the electrolyte layer can be effectively reduced, the transmission distance of lithium ions in the battery is shortened, and the energy density and rate performance of the battery are improved.

[0016] By means of the above technical means combining dry and wet methods, while achieving close contact between the active material and the electrolyte, the thickness of the electrolyte layer can be effectively controlled, and the problem that the conductivity of the electrolyte sheet layer decreases due to long-term immersion of solvent molecules can be avoided, achieving the purpose of improving battery performance.

[0017] In the present invention, if spraying wetting is not carried out and the electrolyte layer is directly compounded on the surface of the positive electrode plate in a pure dry method, the combination between the electrolyte layer and the electrode plate will be unstable, and the density of the electrolyte layer will also decrease, resulting in an increase in the contact impedance between the electrode and the electrolyte and a deterioration of battery performance.

[0018] Preferably, the preparation method of the positive electrode plate in step (1) includes:

[0019] Mix the positive active material, electrolyte, conductive agent, binder and solvent to obtain a positive electrode slurry, coat the positive electrode slurry on the surface of the positive current collector, perform the first drying and the first rolling to obtain the positive electrode plate.

[0020] The positive active material, electrolyte, conductive agent, binder and solvent in the present invention are all conventional technical choices and substances applicable to solid-state batteries, and are all applicable in the present invention. For example, the positive active material can be selected from nickel-cobalt-manganese ternary positive electrode materials, etc., the electrolyte can be selected from sulfide electrolytes, etc., the binder can be selected from polyvinylidene fluoride, etc., the solvent can be selected from isobutyl isobutyrate, etc., and the mass ratio between each substance is also a conventional technical choice.

[0021] Preferably, the thickness of the positive current collector is 4 - 15 μm, such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, etc.

[0022] Preferably, the tape running speed of the positive current collector during the coating process is 0.2 - 50 m / s, such as 0.2 m / s, 0.5 m / s, 0.8 m / s, 1 m / s, 5 m / s, 10 m / s, 15 m / s, 20 m / s, 25 m / s, 30 m / s, 35 m / s, 40 m / s, 45 m / s or 50 m / s, etc.

[0023] Preferably, the temperature of the first drying is 60 to 150 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, etc.

[0024] Preferably, the time of the first drying is 10 to 600 s, such as 10 s, 30 s, 50 s, 100 s, 150 s, 200 s, 250 s or 300 s, etc.

[0025] Preferably, the pressure of the first rolling is 0.4 to 8 t / cm, such as 0.4 t / cm, 0.5 t / cm, 1 t / cm, 2 t / cm, 3 t / cm, 4 t / cm, 5 t / cm, 6 t / cm, 7 t / cm or 8 t / cm, etc.

[0026] Preferably, the liquid for spray wetting in step (1) includes an organic solvent.

[0027] In the present invention, wetting with an organic solvent is sufficient. If an aqueous solvent is selected, it will react violently with the sulfide electrolyte to generate the toxic gas hydrogen sulfide.

[0028] Preferably, the organic solvent includes any one or a combination of at least two of cyclohexane, isobutyl isobutyrate, anisole, dichloromethane or acrylonitrile.

[0029] In the present invention, the selection of the organic solvent is also crucial. If other types of organic solvents are selected, the retention rate of the ionic conductivity of the electrolyte will be relatively low after soaking the electrolyte, and the electrochemical performance of the battery cannot be maintained. For the solvent selected in the present invention, the conductivity of the electrolyte is basically not affected after soaking.

[0030] Preferably, the spray flow rate of the spray wetting in step (1) is 1 to 6 L / min, such as 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min or 6 L / min, etc.

[0031] In the present invention, if the spray flow rate of the spray wetting in step (1) is too small, it is not conducive to the adsorption of the solid electrolyte composite powder on the electrode surface, resulting in insufficient tight bonding between the electrolyte layer and the electrode. If the spray flow rate is too large, it will cause an excessive amount of solvent on the surface of the electrode sheet, a longer drying time, a longer contact time between the electrolyte and the solution, and a greater decrease in the conductivity of the electrolyte layer.

[0032] Preferably, the solid electrolyte composite powder in step (1) is a substance obtained by mixing a solid electrolyte and a binder.

[0033] Preferably, after spraying the solid electrolyte composite powder in step (1), a second drying is performed.

[0034] Preferably, the temperature of the second drying is 60 to 150 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, etc.

[0035] Preferably, the time of the second drying is 10 to 600 s, such as 10 s, 30 s, 50 s, 100 s, 150 s, 200 s, 250 s or 300 s, etc., preferably 30 to 300 s.

[0036] Preferably, the thickness of the solid electrolyte layer in the semi-finished cell in step (1) is ≤ 20 μm, such as 5 μm, 8 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc.

[0037] By using the preparation method provided by the present invention, a thinner electrolyte layer can be prepared.

[0038] Preferably, the preparation method of the negative electrode sheet in step (1) includes:

[0039] Mixing a negative electrode active material, an electrolyte, a conductive agent, a binder and a solvent to obtain a negative electrode slurry, coating the negative electrode slurry on the surface of a negative electrode current collector, performing a third drying, and performing a second rolling to obtain the negative electrode sheet.

[0040] The negative electrode active material, electrolyte, conductive agent, binder and solvent in the present invention are all conventional technical choices and are substances applicable to solid-state batteries, and the present invention is applicable to all of them. For example, the negative electrode active material can be selected from graphite materials, etc., the electrolyte can be selected from sulfide electrolytes, etc., the binder can be selected from polyvinylidene fluoride, etc., the solvent can be selected from isobutyl isobutyrate, etc., and the mass ratio between each substance is also a conventional technical choice.

[0041] Preferably, the thickness of the negative electrode current collector is 2 to 10 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc.

[0042] Preferably, the temperature of the third drying is 60 to 120 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C, etc.

[0043] Preferably, the time of the third drying is 10 to 600 s, such as 30 s, 50 s, 100 s, 150 s, 200 s, 250 s or 300 s, etc.

[0044] Preferably, the compounding in step (2) includes vacuum hot pressing compounding.

[0045] Preferably, the temperature of the vacuum hot pressing composite is 60 to 120 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C, etc.

[0046] Preferably, the pressure of the vacuum hot pressing composite is 200 to 1000 MPa, such as 200 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, 900 MPa or 1000 MPa, etc.

[0047] Preferably, the time of the vacuum hot pressing composite is 300 to 1800 s, such as 300 s, 500 s, 800 s, 1000 s, 1300 s, 1500 s or 1800 s, etc.

[0048] As a preferred technical solution, the preparation method includes the following steps:

[0049] (1) Spray and wet the positive electrode plate or the negative electrode plate, with an organic solvent at a spray flow rate of 1 to 6 L / min, and then directly spray the solid electrolyte composite powder onto the surface of the wetted positive electrode plate or negative electrode plate, and dry at 60 to 150 °C for 10 to 600 s, and press to obtain a semi-finished battery cell;

[0050] (2) Vacuum hot press and composite the other electrode plate of the electrode and the semi-finished battery cell described in step (1) at a pressure of 200 to 1000 MPa at 60 to 120 °C for 300 to 1800 s to obtain the all-solid-state battery;

[0051] The preparation method of the positive electrode plate includes: mixing a positive electrode active material, an electrolyte, a conductive agent, a binder and a solvent to obtain a positive electrode slurry, coating the positive electrode slurry on the surface of a positive electrode current collector with a thickness of 4 to 15 μm, and performing first drying at 60 to 150 °C for 10 to 600 s, and performing first rolling at a pressure of 0.4 to 8 t / cm to obtain the positive electrode plate;

[0052] The preparation method of the negative electrode plate includes:

[0053] Mixing a negative electrode active material, an electrolyte, a conductive agent, a binder and a solvent to obtain a negative electrode slurry, coating the negative electrode slurry on the surface of a negative electrode current collector with a thickness of 2 to 10 μm, performing third drying at 60 to 120 °C for 10 to 600 s, and performing second rolling to obtain the negative electrode plate.

[0054] In a second aspect, the present invention also provides an all-solid-state battery, and the all-solid-state battery is prepared by the preparation method of the all-solid-state battery as described in the first aspect.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention prepares an all-solid-state battery by a method combining dry and wet processes. The preparation of the electrolyte layer uses semi-dry pressing instead of wet mixing. By spraying and wetting the electrode sheets and combining powder spraying, composite electrolyte particles are used to replace the electrolyte slurry. This not only avoids the problem of serious decline in ionic conductivity due to the long soaking time of the electrolyte in the solvent during the wet process but also ensures the contact between the electrolyte layer and the electrode layer, reduces the internal impedance of the battery, and improves the reversible capacity and cycle life of the solid-state battery. For the all-solid-state battery provided by the present invention, during the preparation process, the flow rate of spray wetting is regulated and a preferred organic solvent is selected. The first discharge capacity at 0.1C can reach more than 170.1 mAh / g, the first efficiency at 0.1C can reach more than 79.4%, the capacity retention rate after 50 cycles at 0.5C can reach more than 88.2%, and the ionic conductivity of the electrolyte can reach more than 3.1 mS / cm. Description of the Drawings

[0057] Figure 1 It is a test result diagram of the ionic conductivity of the electrolytes provided for Example 1 and Comparative Example 1. Detailed Embodiments

[0058] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0059] Example 1

[0060] This example provides a preparation method for an all-solid-state battery. The preparation method includes the following steps:

[0061] The positive electrode sheet of the solid-state battery, its components and weight parts are as follows: LiNi with a particle size D50 of 5 μm 0.8 Co 0.1 Mn 0.1 O2 7.0 Kg, SP 0.2 Kg, PVDF 0.3 Kg, sulfide electrolyte LPSC with a particle size D50 of 4 μm 1.6 2.5 Kg, isobutyl isobutyrate 12 Kg.

[0062] The electrolyte layer of the solid-state battery, its components and weight parts are as follows: sulfide solid electrolyte LPSC with a particle size of 10 μm 1.6 5 Kg, PTFE 0.25 Kg.

[0063] The negative electrode sheet of the solid-state battery, its components and weight portions are as follows: 3.5 Kg of graphite with a D50 particle size of 13 μm, 0.05 Kg of SP, 0.15 Kg of PVDF, 1.3 Kg of sulfide electrolyte with a D50 particle size of 10 μm, and 6 Kg of isobutyl isobutyrate.

[0064] The steps of its preparation method are as follows:

[0065] (1) Under a dew point atmosphere of -50, uniformly disperse PVDF powder in the isobutyl isobutyrate solution, stir at a speed of 1000 rpm for 2 h to form a colloidal solution S1, add NCM811 and SP to the colloidal solution S1 and stir for 120 min to obtain S2, add the electrolyte powder to S2 and continue to stir for 30 min to obtain S3, coat S3 on an aluminum foil with a thickness of 10 μm, adjust the oven temperature to 120 °C, and the running speed of the electrode sheet is 2 m / S to obtain a dried positive electrode sheet, and roll press it under a pressure of 6 t / cm after drying to obtain the positive electrode sheet;

[0066] (2) Under a dew point atmosphere of -50, add the isobutyl isobutyrate solution to a liquid sprayer, with a spray flow rate of 4 L / min, wet the positive electrode sheet, add the mixed composite electrolyte to a powder sprayer, with a flow rate of 10 g / min, uniformly spray the composite electrolyte on the wetted positive electrode sheet, and then transfer the electrode sheet to an oven through a control device for moving baking, with a baking temperature of 120 °C and a baking time of 80 s, and press it after drying to obtain a semi-finished battery cell (the thickness of the electrolyte layer in the semi-finished battery cell is 15 μm);

[0067] (3) Cover the negative electrode sheet on one side of the electrolyte sheet, and perform vacuum hot pressing and compounding at a pressure of 500 MPa at 80 °C for 600 s to obtain the said all-solid-state battery;

[0068] Among them, the preparation method of the negative electrode sheet is: add graphite and SP to the colloidal solution S4 (with the same composition as the colloidal solution S1) and stir for 120 min to obtain S5, add the electrolyte powder to S5 and continue to stir for 30 min to obtain S6, coat S6 on a copper foil with a thickness of 8 μm to obtain the negative electrode sheet, adjust the oven temperature to 120 °C, and the running speed of the electrode sheet is 2 m / S to obtain a dried negative electrode sheet, and roll press it to obtain the negative electrode sheet for standby.

[0069] Example 2

[0070] This example provides a preparation method of an all-solid-state battery, and the said preparation method includes the following steps:

[0071] The positive electrode sheet of the solid-state battery, its components and weight portions are as follows: LiNi with a D50 particle size of 5 μm 0.8 Co 0.1 Mn 0.1O27.0 Kg, SP 0.2 Kg, PVDF 0.3 Kg, sulfide electrolyte LPSC with a particle size D50 of 4 μm 1.6 2.5 Kg, isobutyl isobutyrate 12 Kg.

[0072] Solid-state battery electrolyte layer, its components and weight parts are: sulfide solid electrolyte LPSC with a particle size of 10 μm 1.6 5 Kg, PTFE 0.25 Kg.

[0073] Solid-state battery negative electrode sheet, its components and weight parts are: graphite 3.5 Kg with a particle size D50 of 13 μm, SP 0.05 Kg, PVDF 0.15 Kg, sulfide electrolyte 1.3 Kg with a particle size D50 of 10 μm, isobutyl isobutyrate 6 Kg.

[0074] The steps of its preparation method are as follows:

[0075] (1) Under a -50 dew point atmosphere, uniformly disperse PVDF powder in isobutyl isobutyrate solution, stir at a speed of 1000 rpm for 2 h to form glue solution S1, add NCM811 and SP to glue solution S1 and stir for 120 min to obtain S2, add electrolyte powder to S2 and continue to stir for 30 min to obtain S3, coat S3 on an aluminum foil with a thickness of 10 μm, adjust the oven temperature to 150 °C, and the running speed of the electrode sheet is 2 m / S to obtain a dried positive electrode sheet (drying time 30 s), and roll press with a pressure of 8 t / cm after drying to obtain the positive electrode sheet;

[0076] Among them, the preparation method of the negative electrode sheet is: add graphite and SP to glue solution S4 (with the same composition as glue solution S1) and stir for 120 min to obtain S5, add electrolyte powder to S5 and continue to stir for 30 min to obtain S6, coat S6 on a copper foil with a thickness of 8 μm to obtain the negative electrode sheet, adjust the oven temperature to 100 °C, and the running speed of the electrode sheet is 2 m / S to obtain a dried negative electrode sheet, and roll press to obtain the negative electrode sheet for standby;

[0077] (2) Under a -50 dew point atmosphere, add isobutyl isobutyrate solution to a liquid sprayer, the spray flow rate is 1 L / min to wet the positive electrode sheet, add the mixed composite electrolyte to a powder spraying instrument, the flow rate is 10 g / min, uniformly spray the composite electrolyte on the wetted positive electrode sheet, and then transfer the electrode sheet to an oven through a control device for moving baking, the baking temperature is 150 °C, and the baking time is 30 s, and press after drying to obtain a semi-finished battery cell (the thickness of the electrolyte layer in the semi-finished battery cell is 18 μm);

[0078] (3)Cover the positive electrode sheet on one side of the electrolyte sheet, and perform vacuum hot pressing and compounding at a pressure of 800 MPa and a temperature of 60 °C for 400 s to obtain the all-solid-state battery.

[0079] Example 3

[0080] The difference between this example and Example 1 is that in step (2) of this example, the drying temperature is 150 °C, the spray flow rate is 6 L / min, and the organic solvent is cyclohexane.

[0081] The remaining preparation methods and parameters are the same as those in Example 1.

[0082] Example 4

[0083] The difference between this example and Example 1 is that in step (2) of this example, the spray flow rate is 0.5 L / min.

[0084] The remaining preparation methods and parameters are the same as those in Example 1.

[0085] Example 5

[0086] The difference between this example and Example 1 is that in step (2) of this example, the spray flow rate is 6.5 L / min.

[0087] The remaining preparation methods and parameters are the same as those in Example 1.

[0088] Example 6

[0089] The difference between this example and Example 1 is that in the spray wetting process of this example, the solvent is tetrahydrofuran.

[0090] The remaining preparation methods and parameters are the same as those in Example 1.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that after preparing the positive electrode sheet and the negative electrode sheet in this comparative example, the preparation method of the electrolyte layer is as follows:

[0093] Add electrolyte powder and binder PVDF into isobutyl isobutyrate solution to prepare electrolyte slurry, uniformly coat the electrolyte slurry on the positive electrode sheet, the coating thickness is 100 μm, then bake in an oven at 90 °C for 20 min; press to obtain a semi-finished battery cell, and then perform vacuum hot pressing and compounding on the negative electrode sheet and the semi-finished battery cell to obtain the all-solid-state battery.

[0094] The remaining preparation methods and parameters are the same as those in Example 1.

[0095] Figure 1 Shows the test result diagrams of the ionic conductivity of the electrolytes provided in Example 1 and Comparative Example 1. Combining Figure 1And the calculation formula of conductivity, where R0 represents the resistance of the electrolyte sheet tested after a short period of immersion in the solvent, R sol It represents the test resistance after immersion in an organic solvent. According to the ionic conductivity derivation formula: σ=L / (R·A), where σ is the ionic conductivity, L is the thickness of the test electrolyte sheet, R is the test resistance, and A is the area of the test electrolyte sheet, it is calculated that the electrolyte conductivity after short-term contact with the solvent is 3.2mS / cm, and the ionic conductivity of the electrolyte sheet after long-term immersion in the solvent is 1.9mS / cm. It can be concluded from the above results that the ionic conductivity of the electrolyte layer obtained by the preparation method provided by the present invention is significantly improved.

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 1 is that after the positive electrode sheet and the negative electrode sheet are prepared in this comparative example, the preparation method of the electrolyte layer is:

[0098] Sulfide Electrolyte LPSC 1.6 It is fully mixed and ground with PTFE, pressed into an electrolyte membrane (membrane thickness 100um) and set aside for later use. The electrolyte membrane is compounded with the positive electrode sheet, and then compounded with the negative electrode sheet.

[0099] The rest of the preparation methods and parameters were the same as those in Example 1.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that in step (2) of this comparative example, the positive electrode plate is not wetted, and the solid electrolyte composite powder is directly sprayed.

[0102] The rest of the preparation method is consistent with the parameter budget embodiment 1.

[0103] Comparative Example 4

[0104] The difference between this comparative example and Example 2 is that in step (2) of this comparative example, the negative electrode plate is not wetted, and the solid electrolyte composite powder is directly sprayed.

[0105] The rest of the preparation method is consistent with parameter budget embodiment 2.

[0106] The electrochemical performance of the all-solid-state batteries prepared in Examples 1-6 and Comparative Examples 1-4 was tested under the following test conditions:

[0107] 0.1C, 0.5C; 2.80-4.25V, the first charge specific capacity, the first coulomb efficiency, and the 0.5C room temperature cycle performance were measured, and the results are shown in Table 1. Then, the electrolyte sheet and the electrolyte after solution soaking were pressed into sheets to measure the ionic conductivity, and the results are also shown in Table 1:

[0108] Table 1

[0109]

[0110]

[0111] From the data results of Example 1 and Examples 4 and 5, it can be seen that during the spray wetting process, if the spray flow rate is too small, the contact between the electrode and the electrolyte will become poor, while if the spray flow rate is too large, the ionic conductivity of the electrolyte will decrease severely. Both will lead to a deterioration in the cycle performance of the battery.

[0112] From the data results of Example 1 and Example 6, it can be seen that choosing other types of organic solvents will lead to a severe decrease in the ionic conductivity of the electrolyte, and both the capacity and cycle performance of the battery will be affected.

[0113] From the data results of Example 1 and Comparative Example 1, it can be seen that when preparing all-solid-state batteries by pure wet methods, problems such as a decrease in the ionic conductivity of the electrolyte, a decrease in battery capacity and cycle performance will occur.

[0114] From the data results of Example 1 and Comparative Example 2, it can be seen that first preparing a solid electrolyte membrane (dry method) and then compounding it is also difficult to achieve a thinner electrolyte layer. The diffusion path of lithium ions increases, and the cycle performance of the battery decreases severely.

[0115] From the data results of Example 1 and Comparative Example 3, and Example 2 and Comparative Example 4, it can be seen that without the wetting process, it is very difficult to achieve close contact between the electrolyte layer and the electrode sheet, and the cycle performance of the battery decreases.

[0116] In summary, the present invention prepares all-solid-state batteries by a method combining dry and wet methods. The electrolyte layer is prepared by semi-dry pressing instead of wet mixing. The electrode sheet is spray-wetted, and at the same time, the powder spraying method is combined. Composite electrolyte particles are used to replace the electrolyte slurry. This not only avoids the problem of severe decrease in ionic conductivity due to the long soaking time of the electrolyte in the solvent during the wet process, realizes close contact between the active material and the electrolyte, and can effectively control the thickness of the electrolyte layer, but also ensures the contact between the electrolyte layer and the electrode layer, reduces the internal impedance of the battery, and improves the reversible capacity and cycle life of the all-solid-state battery. For the all-solid-state battery provided by the present invention, the flow rate of spray wetting is regulated during the preparation process, and a preferred organic solvent is selected. Its first discharge capacity at 0.1C can reach more than 170.1 mAh / g, the first efficiency at 0.1C can reach more than 79.4%, the capacity retention rate after 50 cycles at 0.5C can reach more than 88.2%, and the ionic conductivity of the electrolyte can reach more than 3.1 mS / cm.

[0117] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing an all-solid-state battery, characterized in that The preparation method includes the following steps: (1) Spray and wet the positive electrode sheet or the negative electrode sheet, and then directly spray the solid electrolyte composite powder onto the surface of the wetted positive electrode sheet or negative electrode sheet, and press to obtain a semi-finished battery cell; the spray flow rate of the spray wetting is 1-6 L / min; The liquid for the spray wetting includes an organic solvent; the organic solvent includes any one or a combination of at least two of cyclohexane, isobutyl isobutyrate, anisole, dichloromethane or acrylonitrile; (2) Composite the other electrode sheet with the semi-finished battery cell obtained in step (1) to obtain the all-solid-state battery; Both the positive electrode sheet and the negative electrode sheet are prepared by a wet slurry coating method.

2. The preparation method of the all-solid-state battery according to claim 1, wherein, The preparation method of the positive electrode sheet in step (1) includes: Mix the positive active material, electrolyte, conductive agent, binder and solvent to obtain a positive electrode slurry, coat the positive electrode slurry on the surface of the positive current collector, perform first drying and first rolling to obtain the positive electrode sheet.

3. The method for preparing an all-solid-state battery according to claim 2, wherein The thickness of the positive current collector is 4-15 μm.

4. The preparation method of the all-solid-state battery according to claim 2, characterized in that, The tape running speed of the positive current collector during the coating process is 0.2-50 m / s.

5. The method for preparing an all-solid-state battery according to claim 4, characterized in that, The temperature of the first drying is 60-150 °C.

6. The preparation method of the all-solid-state battery according to claim 4, wherein The time of the first drying is 10-600 s.

7. The preparation method of the all-solid-state battery according to claim 4, wherein, The pressure of the first rolling is 0.4-8 t / cm.

8. The method for preparing an all-solid-state battery according to claim 1, characterized in that, The solid electrolyte composite powder in step (1) is a substance obtained by mixing a solid electrolyte and a binder.

9. The method for preparing an all-solid-state battery according to claim 1, wherein After spraying the solid electrolyte composite powder in step (1), perform second drying.

10. The preparation method of the all-solid-state battery according to claim 9, characterized in that, The temperature of the second drying is 60-150 °C.

11. The preparation method of the all-solid-state battery according to claim 9, characterized in that, The time of the second drying is 10-600 s.

12. The preparation method of the all-solid-state battery according to claim 9, wherein, The time of the second drying is 30-300 s.

13. The preparation method of the all-solid-state battery according to claim 1, wherein The thickness of the solid electrolyte layer in the semi-finished battery cell in step (1) ≤ 20 μm.

14. The method for preparing an all-solid-state battery according to claim 1, wherein, The preparation method of the negative electrode sheet in step (1) includes: Mix the negative active material, electrolyte, conductive agent, binder and solvent to obtain a negative electrode slurry, coat the negative electrode slurry on the surface of the negative current collector, perform third drying and second rolling to obtain the negative electrode sheet.

15. The preparation method of the all-solid-state battery according to claim 14, wherein The thickness of the negative current collector is 2-10 μm.

16. The method for preparing an all-solid-state battery according to claim 14, wherein The temperature of the third drying is 60-120 °C.

17. The preparation method of the all-solid-state battery according to claim 14, wherein, The time of the third drying is 10-600 s.

18. The preparation method of the all-solid-state battery according to claim 1, characterized in that, The composite in step (2) includes vacuum hot pressing composite.

19. The method for preparing an all-solid-state battery according to claim 18, wherein, The temperature of the vacuum hot pressing composite is 60-120 °C.

20. The preparation method of the all-solid-state battery according to claim 18, wherein, The pressure of the vacuum hot pressing composite is 200-1000 MPa.

21. The preparation method of the all-solid-state battery according to claim 18, wherein The time of the vacuum hot pressing composite is 300-1800 s.

22. The preparation method of the all-solid-state battery according to claim 1, characterized in that, The preparation method includes the following steps: (1) Spray and wet the positive electrode sheet or the negative electrode sheet, perform spray wetting with an organic solvent at a spray flow rate of 1-6 L / min, then directly spray the solid electrolyte composite powder onto the surface of the wetted positive electrode sheet or negative electrode sheet, and dry at 60-150 °C for 10-600 s, and press to obtain a semi-finished battery cell; (2) Composite the other electrode sheet with the semi-finished battery cell obtained in step (1) under a pressure of 200-1000 MPa at 60-120 °C for 300-1800 s by vacuum hot pressing to obtain the all-solid-state battery; The preparation method of the positive electrode sheet includes: mixing a positive electrode active material, an electrolyte, a conductive agent, a binder, and a solvent to obtain a positive electrode slurry, coating the positive electrode slurry on the surface of a positive electrode current collector with a thickness of 4 to 15 μm, performing a first drying at 60 to 150 °C for 10 to 600 s, and performing a first rolling at a pressure of 0.4 to 8 t / cm² to obtain the positive electrode sheet; The preparation method of the negative electrode sheet includes: mixing a negative electrode active material, an electrolyte, a conductive agent, a binder, and a solvent to obtain a negative electrode slurry, coating the negative electrode slurry on the surface of a negative electrode current collector with a thickness of 2 to 10 μm, performing a third drying at 60 to 120 °C for 10 to 600 s, and performing a second rolling to obtain the negative electrode sheet.

23. A all-solid-state battery, characterized in that, The all-solid-state battery is prepared by the preparation method of the all-solid-state battery according to any one of claims 1-22.

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