Solid electrolyte membrane, preparation method thereof, all-solid-state battery and manufacturing method thereof

Abstract

The present invention provides a solid electrolyte membrane, a preparation method thereof, and an all-solid-state battery and a manufacturing method thereof. The solid electrolyte membrane includes a solid electrolyte, a binder, and a plasticizer; wherein the mass of the plasticizer accounts for 0.1wt% to 10wt%. The present invention significantly increases the flexibility of the solid electrolyte membrane without compromising ionic conductivity by adding a specific amount of plasticizer. Furthermore, by providing a flexible material layer on a transfer device to apply pressure to the solid electrolyte membrane and perform transfer printing, the pressure imbalance caused by thickness differences between different regions is effectively reduced, the contact area of the solid electrolyte membrane is increased, and overpressure is eliminated. After transfer printing, hot pressing and cold pressing are performed to further ensure that the resulting composite electrode sheet is free of deformation and bending. The performance of the assembled all-solid-state battery is optimized and enhanced. The process provided by the present invention is simple, has good compatibility with traditional lamination processes, and is convenient for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of lithium-ion batteries and relates to a solid electrolyte membrane, a preparation method thereof, an all-solid-state battery and a manufacturing method thereof. Background Art

[0002] At present, lithium-ion batteries have been widely used in new energy vehicles, digital electronic products and energy storage systems, among which liquid lithium batteries account for the largest proportion. Compared with traditional liquid lithium batteries, all-solid-state lithium batteries have many advantages, especially because they use solid electrolytes that are not easy to ignite and burn to form the battery, which has high safety. Solid electrolyte membrane is one of the key materials of all-solid-state lithium-ion batteries. It can act as an insulator while providing a lithium ion transmission channel. At present, there are two main technical routes for the preparation of all-solid-state lithium batteries. One is to coat the all-solid-state electrolyte slurry on the positive / negative electrode sheets, and then stack and assemble them after drying; the other is to transfer the prepared solid electrolyte membrane to the positive / negative electrode sheets, and then stack and assemble them with the negative / positive electrodes.

[0003] For example, CN113659108A mentions a solution to reduce interfacial impedance by coating a solid electrolyte slurry on the positive electrode active material layer. This method can improve the interfacial contact problem to a certain extent, but this method requires that the solvent and binder of the positive electrode active material slurry and the solid electrolyte slurry have a certain degree of compatibility; moreover, directly coating on the positive electrode active material layer will result in poor thickness consistency of the solid electrolyte layer, and the positive electrode-solid electrolyte contact interface formed by this method will have a situation where the positive electrode active material and the solid electrolyte mix with each other, which will directly affect the performance of the solid-state battery. In addition, the coating process is time-consuming and is not conducive to large-scale mass production.

[0004] The transfer method has the advantages of simple operation and convenience for mass production, but there are also many problems to be solved regarding the solid electrolyte membrane transfer process. For example, when preparing solid electrolyte slurry, since the solid electrolyte membrane must maintain insulation and high ionic conductivity, it has high requirements for solvents and binders, but the types of solvents and binders available are limited, resulting in poor flexibility and easy brittle fracture of the prepared solid electrolyte membrane; in addition, the positive / negative electrode surface of traditional liquid lithium batteries is a solid-liquid contact interface, while the contact between the positive / negative electrode and the solid electrolyte membrane in all-solid-state lithium batteries is a solid-solid contact interface. The problem of insufficient contact between the solid electrolyte membrane and the positive / negative electrode sheets is not conducive to ion transmission.

[0005] The above two problems should be avoided as much as possible, but at present, when manufacturing sulfide solid electrolyte membranes with poor flexibility, the solid electrolyte membrane-positive / negative electrode composite plates obtained after transfer often bend, which will aggravate and highlight the above two problems, and ultimately lead to battery performance loss.

[0006] Specifically, during the transfer process, the positive / negative electrode sheets are subjected to pressure, and the particles on the electrode sheets squeeze each other, causing the electrode sheets to bend after transfer. The thickness difference between different areas on the electrode sheet will cause the thinner areas to be subjected to less pressure during the transfer process, while the thicker areas are subjected to too much pressure, causing the thicker areas to be damaged due to overpressure, making the solid-solid interface formed by the positive / negative electrode sheets in the thinner areas and the solid electrolyte membrane less contact. CN113488691A mentions a method for preparing a composite electrolyte membrane, in which the positive electrode sheet and the electrolyte membrane are pressed together by transfer, and then the positive electrode current collector aluminum foil is removed, and then assembled with the negative electrode sheet into a button battery. Although this method can improve the interface problem between the positive electrode material and the solid electrolyte membrane to a certain extent, there are still unavoidable thickness differences between different areas on the same electrode sheet or electrolyte membrane, so the traditional transfer method cannot effectively improve the interface contact problem. Moreover, the operation of removing the positive electrode current collector after transfer mentioned in the patent will result in no current collector covering the positive electrode after lamination. Therefore, this method is only suitable for the preparation of single-layer button batteries and is not suitable for large-scale mass production.

[0007] Therefore, there is still a need to provide a new manufacturing solution for sulfide solid electrolyte membranes and all-solid-state batteries containing the same, so as to solve the problems currently encountered in the preparation and transfer of solid electrolyte membranes. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention aims to provide a solid electrolyte membrane, a preparation method thereof, and an all-solid-state battery and a manufacturing method thereof, wherein the solid electrolyte membrane comprises a solid electrolyte, a binder, and a plasticizer; the mass of the plasticizer accounts for 0.1wt% to 10wt% based on the mass of the solid electrolyte membrane as 100wt%. The present invention significantly increases the flexibility of the solid electrolyte membrane without compromising ionic conductivity by adding a specific amount of plasticizer. Furthermore, by providing a flexible material layer on the transfer device to apply pressure to the solid electrolyte membrane and perform transfer, the pressure imbalance caused by thickness differences between different regions during the transfer process is effectively reduced, the contact area between the solid electrolyte membrane and the electrode is increased, and overpressure is eliminated. After transfer, hot pressing and cold pressing are performed to further ensure flatness. The resulting composite electrode is free of deformation and bending, and the performance of the assembled all-solid-state battery is optimized and enhanced. The process provided by the present invention is simple, has good compatibility with traditional lamination processes, and is convenient for large-scale production.

[0009] Reduce the pressure imbalance caused by the thickness difference between different areas of the electrode or electrolyte membrane

[0010] During the transfer process, the flexible material layer deforms appropriately under pressure, effectively reducing pressure imbalances caused by thickness differences between different regions of the electrode or electrolyte membrane, increasing the contact area between the solid electrolyte membrane and the positive / negative electrode, and eliminating local overpressure. After transfer, the solid electrolyte membrane-positive / negative electrode composite is subjected to hot pressing and cold pressing to obtain a flat, unbendable composite electrode, which is then assembled into a solid-state battery. The process provided by the present invention is simple and compatible with traditional lamination processes, facilitating large-scale mass production.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a solid electrolyte membrane comprising a solid electrolyte, a binder and a plasticizer; based on 100 wt % of the mass of the solid electrolyte membrane, the mass of the plasticizer accounts for 0.1 wt % to 10 wt %.

[0013] The present invention adds a plasticizer component to the solid electrolyte membrane and controls the plasticizer component to a specific content, thereby greatly improving the flexibility of the obtained solid electrolyte membrane without affecting the ionic conductivity of the solid electrolyte. Therefore, the obtained solid electrolyte membrane can be wound and stored, and is conducive to subsequent processing such as maintaining the shape and integrity of the solid electrolyte membrane during transfer to the electrode, is not prone to brittle fracture, and is conducive to improving the solid-solid contact state between the electrode and the electrode, effectively increasing the contact area while reducing the bending caused by transfer.

[0014] In the solid electrolyte membrane described in the present invention, the binder can provide adhesion and a certain rigidity to the solid electrolyte, while the plasticizer can provide flexibility; however, because the binder and plasticizer will hinder the transmission of lithium ions in the electrolyte membrane and reduce the ionic conductivity of the electrolyte membrane, the content of both should not be too large.

[0015] It should be noted that, based on the mass of the solid electrolyte membrane as 100wt%, the mass of the plasticizer accounts for 0.1wt% to 10wt%, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, etc., but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0016] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0017] As a preferred technical solution of the present invention, based on the mass of the solid electrolyte membrane being 100wt%, the mass of the binder accounts for 0.5wt% to 5wt%, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, etc., but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0018] Preferably, based on the mass of the solid electrolyte membrane as 100wt%, the mass of the solid electrolyte accounts for 85wt% to 99.4wt%, for example, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt% or 99.4wt%, etc., but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0019] As a preferred technical solution of the present invention, one side surface of the solid electrolyte membrane is covered with release paper for winding and storage or transfer processing.

[0020] Since the solid electrolyte membrane of the present invention has a certain flexibility due to the addition of a plasticizer, a release paper can be added to one side of the solid electrolyte membrane for rolling up and storage. During subsequent use, the presence of the release paper can avoid adhesion or contamination caused by direct contact with the solid electrolyte during cutting and transfer pressure application.

[0021] Preferably, the thickness of the solid electrolyte membrane is 5 to 400 μm, for example, 5 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm or 400 μm, but is not limited to the listed values. Other values not listed within the above numerical range are also applicable.

[0022] As a preferred technical solution of the present invention, the solid electrolyte includes a sulfide solid electrolyte.

[0023] Preferably, the sulfide solid electrolyte includes any one of Li2S-GeS2, Li2S-P2S5 or Li2S-SiS2 or a combination of at least two of them. Typical but non-limiting examples of the combination include a combination of Li2S-GeS2 and Li2S-P2S5, a combination of Li2S-GeS2 and Li2S-SiS2, or a combination of Li2S-P2S5 and Li2S-SiS2.

[0024] Preferably, the binder comprises any one or a combination of at least two of polyvinylidene fluoride, styrene-butadiene rubber or organic olefinic acid, typical but non-limiting examples of which include a combination of polyvinylidene fluoride and styrene-butadiene rubber, a combination of polyvinylidene fluoride and organic olefinic acid or a combination of styrene-butadiene rubber and organic olefinic acid.

[0025] Preferably, the plasticizer comprises diethyl phthalate and / or tributyl citrate.

[0026] In a second aspect, the present invention provides a method for preparing a solid electrolyte membrane according to the first aspect, the method for preparing the solid electrolyte membrane comprising: uniformly mixing a solid electrolyte, a binder, a plasticizer and a solvent, controlling the mass of the plasticizer to account for 0.1 wt% to 10 wt% of the total mass of the solid electrolyte, the binder and the plasticizer, to prepare a solid electrolyte slurry, coating the solid electrolyte slurry, heating and drying the coating to obtain a solid electrolyte membrane.

[0027] As a preferred technical solution of the present invention, the coating includes coating on the silicone oil side of the release paper.

[0028] Preferably, the heating and drying temperature is 80-110°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C or 110°C, and the time is 2-5h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other values not listed within the above numerical range are also applicable.

[0029] Preferably, the solvent comprises any one or a combination of at least two of N-methylpyrrolidone, dimethylformamide, dimethylacetamide or dimethyl sulfoxide. Typical but non-limiting examples of the combination include a combination of N-methylpyrrolidone and dimethylformamide, a combination of N-methylpyrrolidone and dimethylacetamide, a combination of N-methylpyrrolidone and dimethyl sulfoxide, a combination of dimethylformamide and dimethylacetamide, a combination of dimethylformamide and dimethyl sulfoxide, or a combination of dimethylacetamide and dimethyl sulfoxide.

[0030] In a third aspect, the present invention provides an all-solid-state battery, which contains the solid electrolyte membrane described in the first aspect or the solid electrolyte membrane obtained by the preparation method described in the second aspect.

[0031] The all-solid-state battery of the present invention is preferably a soft-pack battery comprising at least a positive electrode sheet, a negative electrode sheet, the solid electrolyte membrane, and auxiliary materials such as an aluminum-plastic film.

[0032] In a fourth aspect, the present invention provides a method for manufacturing the all-solid-state battery according to the third aspect, the method comprising the following steps:

[0033] (1) preparing a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane, respectively, wherein the solid electrolyte membrane has a release paper; placing the solid electrolyte membrane on the active layer of the positive electrode sheet or the negative electrode sheet, with the release paper facing outward;

[0034] (2) providing a flexible material layer on a transfer device, and transferring the solid electrolyte membrane to the active layer of the positive electrode sheet or the negative electrode sheet by contacting the flexible material layer with the release paper and applying pressure, and then performing hot pressing and then cold pressing to obtain a composite positive electrode sheet or a composite negative electrode sheet;

[0035] (3) Assembling the composite positive electrode sheet or the composite negative electrode sheet of step (2) with the corresponding uncomposite negative electrode sheet or positive electrode sheet to form an all-solid-state battery.

[0036] After adding a specific amount of plasticizer to obtain the solid electrolyte membrane, the present invention further applies pressure to the solid dielectric membrane by providing a flexible material layer on the transfer device and performing transfer printing. This can effectively reduce the pressure imbalance caused by thickness differences between different regions during the transfer process, increase the contact area between the solid electrolyte membrane and the electrode, and eliminate overpressure. After transfer, hot pressing and cold pressing are performed to further ensure flatness. The addition of the plasticizer, transfer through the flexible material layer, and cold pressing and hot pressing cooperate with each other to ensure that the resulting composite positive electrode or composite negative electrode is free of deformation and bending, and the performance of the assembled all-solid-state battery is optimized and enhanced. The process provided by the present invention is simple, has good compatibility with traditional lamination processes, and is convenient for large-scale production.

[0037] As a preferred technical solution of the present invention, the specifications and sizes of the positive electrode sheet, the negative electrode sheet and the solid electrolyte membrane in step (1) are the same.

[0038] Preferably, the release force of the release paper in step (1) is 3 to 60 g, for example, 3 g, 5 g, 10 g, 15 g, 20 g, 25 g, 30 g, 35 g, 40 g, 45 g, 50 g, 55 g or 60 g, etc., but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0039] Preferably, the flexible material layer in step (2) comprises silica gel and / or foam.

[0040] Preferably, the thickness of the flexible material layer in step (2) is 0.5 to 5 mm, for example, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, etc., but is not limited to the listed values. Other values not listed within the above numerical range are also applicable.

[0041] If the flexible material layer is too thin, the effect of reducing the uneven pressure caused by thickness differences will be insignificant. If the flexible material layer is too thick, it will deform significantly and cannot exert effective pressure during transfer, and needs to be replaced frequently.

[0042] Preferably, when the positive electrode sheet or the negative electrode sheet is provided with an active layer only on one side, the current collector of the positive electrode sheet or the negative electrode sheet contacts and applies pressure to the transfer device in step (2) through the flexible material layer.

[0043] It should be noted that the present invention preferably transfers the solid electrolyte membrane only on one of the positive electrode sheet or the negative electrode sheet, and transfers the solid electrolyte membrane accordingly according to the number of active layers set on the electrode sheet itself; taking the transfer of the positive electrode sheet as an example, if the positive electrode sheet is only provided with an active layer of positive electrode material on one side of the current collector, then a solid electrolyte membrane with release paper is only provided on this side, and at this time, the two sides of the outermost layer are release paper and the current collector respectively, and the transfer equipment contacts the release paper and the current collector respectively through the flexible material layer, and applies pressure to perform single-sided transfer; if the positive electrode sheet has an active layer of positive electrode material on both sides of the current collector, then a solid electrolyte membrane with release paper is respectively provided on both sides, and at this time, the two outermost layers are both release paper, and the transfer equipment contacts the release paper on both sides through the flexible material layer, and applies pressure to perform double-sided transfer.

[0044] As a preferred technical solution of the present invention, the transfer pressure in step (2) is 5 to 50 kN, for example, 5 kN, 10 kN, 15 kN, 20 kN, 25 kN, 30 kN, 35 kN, 40 kN, 45 kN or 50 kN, and the temperature is 10 to 50 ° C, for example, 10 ° C, 15 ° C, 20 ° C, 25 ° C, 30 ° C, 35 ° C, 40 ° C, 45 ° C or 50 ° C, but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0045] Preferably, the pressure of the hot pressing in step (2) is 10 to 1000 N, for example, 10 N, 50 N, 100 N, 200 N, 300 N, 400 N, 500 N, 600 N, 700 N, 800 N, 900 N or 1000 N, and the temperature is 40 to 100 ° C, for example, 40 ° C, 45 ° C, 50 ° C, 55 ° C, 60 ° C, 65 ° C, 70 ° C, 75 ° C, 80 ° C, 85 ° C, 90 ° C, 95 ° C or 100 ° C, but is not limited to the listed values, and other values not listed within the above numerical range are also applicable.

[0046] Preferably, the cold pressing pressure in step (2) is 10 to 1000 N, for example, 10 N, 50 N, 100 N, 200 N, 300 N, 400 N, 500 N, 600 N, 700 N, 800 N, 900 N or 1000 N, and the temperature is 0 to 25 ° C, for example, 0 ° C, 5 ° C, 10 ° C, 15 ° C, 20 ° C or 25 ° C, but is not limited to the listed values. Other values not listed within the above numerical range are also applicable.

[0047] Compared with the existing technical solutions, the present invention has at least the following beneficial effects:

[0048] (1) The present invention introduces a plasticizer into the solid electrolyte membrane, which ensures that the solid electrolyte membrane has a high ionic conductivity while improving the flexibility of the membrane. This is beneficial for subsequent processing, such as when transferring to the electrode to maintain the shape and integrity of the solid electrolyte membrane, making it less likely to break. It is also beneficial for improving the solid-solid contact state between the electrode and the membrane, effectively increasing the contact area while reducing the bending caused by transfer, and facilitating large-scale mass production of the solid electrolyte membrane.

[0049] (2) The present invention adds a layer of flexible material to the transfer device, and transfers the solid electrolyte membrane added with plasticizer under this device, so that the pressure in each area can be more balanced, the contact area between the solid electrolyte membrane and the electrode is increased, and the overpressure phenomenon is eliminated; after the transfer, the new hot pressing and cold pressing processes are performed to release the stress between particles generated in the transfer process, and completely solve the problem of bending of the composite electrode. The process flow is simple and easy to operate, and has good compatibility with the traditional lamination process, which is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the coordination of various parts when the solid electrolyte membrane is transferred using the transfer device in step (2) of the manufacturing method described in Application Example 1 of the present invention;

[0051] Figure 2 This is a schematic diagram of the coordination of various parts when the solid electrolyte membrane is transferred using the transfer device in step (2) of the manufacturing method described in Application Example 4 of the present invention;

[0052] In the figure: 1- solid electrolyte membrane, 2- release paper, 31- positive electrode current collector, 32- negative electrode current collector, 41- positive electrode active layer, 42- negative electrode active layer, 5- flexible material layer, 6- transfer equipment. DETAILED DESCRIPTION

[0053] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] Example 1

[0055] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane includes Li2S-GeS2, PVDF (polyvinylidene fluoride) and tributyl citrate with mass fractions of 90.91 wt%, 3.64 wt% and 5.45 wt%, respectively; the thickness of the solid electrolyte membrane is 200 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0056] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone, PVDF and tributyl citrate in a mass ratio of 50:45:2:3 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0057] Example 2

[0058] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-P2S5, PVDF, and diethyl phthalate with mass fractions of 92.6 wt%, 3.7 wt%, and 3.7 wt%, respectively; the thickness of the solid electrolyte membrane is 200 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0059] The preparation method of the solid electrolyte membrane is as follows: Li2S-P2S5, N-methylpyrrolidone, PVDF and diethyl phthalate with a mass ratio of 50:46:2:2 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 100°C for 3 hours to obtain a solid electrolyte membrane.

[0060] Example 3

[0061] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-SiS2, styrene-butadiene rubber, and diethyl phthalate with mass fractions of 96.66 wt%, 3 wt%, and 0.34 wt%, respectively; the thickness of the solid electrolyte membrane is 8 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0062] The preparation method of the solid electrolyte membrane is as follows: Li2S-SiS2, dimethylformamide, styrene-butadiene rubber and diethyl phthalate in a mass ratio of 50:48.27:1.56:0.17 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 80°C for 5 hours to obtain a solid electrolyte membrane.

[0063] Example 4

[0064] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2, an organic olefinic acid, and tributyl citrate with mass fractions of 93.51 wt%, 4.99 wt%, and 1.5 wt%, respectively; the thickness of the solid electrolyte membrane is 400 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0065] The preparation method of the solid electrolyte membrane is as follows: take a mixture of Li2S-GeS2, an organic olefin acid, dimethylformamide and dimethyl sulfoxide in a mass ratio of 50:46.53:2.67:0.8, and tributyl citrate, mix them evenly to form a solid electrolyte slurry, apply the solid electrolyte slurry on the silicone oil side of the release paper, and then dry it at 110°C for 2h to obtain a solid electrolyte membrane.

[0066] Example 5

[0067] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2, PVDF, and tributyl citrate with mass fractions of 95.99 wt%, 3.83 wt%, and 0.18 wt%, respectively; the thickness of the solid electrolyte membrane is 15 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0068] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone, PVDF and tributyl citrate in a mass ratio of 50:45:2:0.2 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0069] Example 6

[0070] This embodiment provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2, PVDF, and tributyl citrate with mass fractions of 90.46 wt%, 3.74 wt%, and 5.8 wt%, respectively; the thickness of the solid electrolyte membrane is 15 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0071] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone, PVDF and tributyl citrate in a mass ratio of 50:45:2:1.5 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0072] Comparative Example 1

[0073] This comparative example provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2 and PVDF with mass fractions of 96.15 wt% and 3.85 wt%, respectively, and does not contain a plasticizer; the thickness of the solid electrolyte membrane is 15 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0074] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone and PVDF with a mass ratio of 50:45:2 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0075] Comparative Example 2

[0076] This comparative example provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2, PVDF and tributyl citrate with mass fractions of 96.11 wt%, 3.84 wt% and 0.05 wt% respectively; the thickness of the solid electrolyte membrane is 15 μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0077] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone, PVDF and tributyl citrate in a mass ratio of 50:45:2:0.05 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0078] Comparative Example 3

[0079] This comparative example provides a solid electrolyte membrane and a preparation method thereof, wherein the solid electrolyte membrane comprises Li2S-GeS2, PVDF and tributyl citrate with mass fractions of 85.09wt%, 3.6wt% and 11.31wt%, respectively; the thickness of the solid electrolyte membrane is 15μm, and one side surface of the solid electrolyte membrane is covered with release paper.

[0080] The preparation method of the solid electrolyte membrane is as follows: Li2S-GeS2, N-methylpyrrolidone, PVDF and tributyl citrate in a mass ratio of 50:45:2:3.5 are mixed evenly to form a solid electrolyte slurry, the solid electrolyte slurry is coated on the silicone oil side of the release paper, and then dried at 90°C for 4 hours to obtain a solid electrolyte membrane.

[0081] Application Example 1

[0082] This application example provides a method for manufacturing an all-solid-state battery, and the method for manufacturing an all-solid-state battery includes:

[0083] (1) preparing a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, respectively, and placing the solid electrolyte membrane on the active layer on one side of the positive electrode sheet, with the release paper facing outward; the solid electrolyte membrane is selected from any one of the solid electrolyte membranes obtained in Examples 1-6 or Comparative Examples 1-3;

[0084] (2) A 3 mm thick silica gel is provided as a flexible material layer on the transfer device, and the solid electrolyte membrane is transferred to the active layer of the positive electrode sheet by contacting the flexible material layer with the release paper and the current collector of the positive electrode sheet and applying a pressure of 10 kN at 25 ° C. Then, hot pressing is performed at 90 ° C. with a pressure of 100 N, and then cold pressing is performed at 15 ° C. with a pressure of 100 N to obtain a composite positive electrode sheet;

[0085] (3) Assembling the composite positive electrode sheet described in step (2) and the corresponding uncomposite negative electrode sheet into an all-solid-state battery.

[0086] Figure 1 This is a schematic diagram of the coordination of the various parts when the solid electrolyte membrane is transferred using the transfer device in step (2) of the manufacturing method of the all-solid-state battery described in this application example. As can be seen from the figure, the solid electrolyte membrane 1 with the release paper 2 is arranged on one side of the positive electrode plate. Specifically, the positive electrode plate includes a positive electrode collector 31 and a positive electrode active layer 41 located on one side of the positive electrode collector 31. The solid electrolyte membrane 1 with the release paper 2 is arranged on the positive electrode active layer 41, and the release paper 2 is arranged outward (i.e., toward the transfer device); a flexible material layer 5 is provided on the transfer device 6, and the flexible material layer 5 is directly in contact with the release paper 2 and the positive electrode collector 31 and applies pressure to transfer the solid electrolyte membrane 1 to the positive electrode active layer 41, thereby completing the transfer process of the solid electrolyte membrane 1.

[0087] The solid electrolyte membranes obtained in Examples 1-6 and Comparative Examples 1-3 were respectively used in Application Example 1 to prepare all-solid-state batteries. The lower limit of the charge and discharge cut-off voltage was set to 2 to 2.5 V, and the upper limit was set to 4 to 4.5 V. The charge and discharge tests were performed on each of the obtained all-solid-state batteries, and the results are shown in Table 1.

[0088] Table 1

[0089] project First coulombic efficiency Capacity retention after 400 cycles Example 1 79.3％ 94.3％ Example 2 78.5.％ 93.3％ Example 3 80.8％ 93.6％ Example 4 77.7％ 95.5％ Example 5 79.8％ 95.1％ Example 6 77.6％ 92.8％ Comparative Example 1 77.0％ 79.6％ Comparative Example 2 75.7％ 81.1％ Comparative Example 3 60.2％ 78.9％

[0090] It can be seen from Table 1 that: when using a flexible material layer for transfer and hot pressing and cold pressing, the all-solid-state batteries made using the solid electrolyte membranes obtained in Examples 1-6 can obtain higher first coulombic efficiency and capacity retention rate; compared with Example 1, the solid electrolyte membrane in Comparative Example 1 does not contain a plasticizer, so the flexibility of the electrolyte layer is poor. During the charge and discharge process, as the battery volume expands, tiny cracks are generated in the electrolyte layer. Lithium dendrites pass through the cracked electrolyte layer, causing micro-short circuits inside the battery, and the capacity retention rate is poor; excessive plasticizer content in Comparative Example 3 will lead to a decrease in the ionic conductivity of the electrolyte layer, and the first coulombic efficiency and capacity retention rate of the battery will be significantly reduced.

[0091] Application Example 2

[0092] This application example provides a method for manufacturing an all-solid-state battery, and the method for manufacturing an all-solid-state battery includes:

[0093] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, and place the solid electrolyte membrane on the active layer on both sides of the positive electrode sheet, with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0094] (2) A 5 mm thick foam is provided as a flexible material layer on the transfer device, and the solid electrolyte membrane is transferred to the active layer of the positive electrode sheet by applying a pressure of 50 kN at 50°C through the contact between the flexible material layer and the release paper. Then, the solid electrolyte membrane is first hot pressed at 40°C with a pressure of 1000 N, and then cold pressed at 0°C with a pressure of 1000 N to obtain a composite positive electrode sheet;

[0095] (3) Assembling the composite positive electrode sheet described in step (2) and the corresponding uncomposite negative electrode sheet into an all-solid-state battery.

[0096] Application Example 3

[0097] This application example provides a method for manufacturing an all-solid-state battery, and the method for manufacturing an all-solid-state battery includes:

[0098] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, respectively, and place the solid electrolyte membrane on the active layer on one side of the negative electrode sheet, with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0099] (2) A 4 mm thick foam is provided as a flexible material layer on the transfer device, and the solid electrolyte membrane is transferred to the active layer of the negative electrode sheet by applying a pressure of 10 kN at 25°C through the contact between the flexible material layer and the release paper. Then, the composite negative electrode sheet is obtained by hot pressing at 80°C with a pressure of 150 N and then cold pressing at 25°C with a pressure of 500 N.

[0100] (3) Assembling the composite negative electrode sheet described in step (2) and the corresponding uncomposite positive electrode sheet into an all-solid-state battery.

[0101] Application Example 4

[0102] This application example provides a method for manufacturing an all-solid-state battery, and the method for manufacturing an all-solid-state battery includes:

[0103] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, and place the solid electrolyte membrane on the active layer on both sides of the negative electrode sheet, with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0104] (2) A 2 mm thick foam is provided as a flexible material layer on the transfer device, and the solid electrolyte membrane is transferred to the active layer of the negative electrode sheet by applying a pressure of 5 kN at 10° C. through the contact between the flexible material layer and the release paper. Then, the solid electrolyte membrane is first hot pressed at 100° C. with a pressure of 10 N, and then cold pressed at 25° C. with a pressure of 50 N to obtain a composite negative electrode sheet;

[0105] (3) Assembling the composite negative electrode sheet described in step (2) and the corresponding uncomposite positive electrode sheet into an all-solid-state battery.

[0106] Figure 2 This is a schematic diagram of the coordination of the various parts when the solid electrolyte membrane is transferred using the transfer device in step (2) of the manufacturing method of the all-solid-state battery described in this application example. As can be seen from the figure, the solid electrolyte membrane 1 with release paper 2 is arranged on both sides of the negative electrode plate. Specifically, the negative electrode plate includes a negative electrode collector 32 and a negative electrode active layer 42 located on both sides of the negative electrode collector 32. The solid electrolyte membrane 1 with release paper 2 is arranged on the negative electrode active layer 42, and the release paper 2 is arranged outward (i.e., toward the transfer device); a flexible material layer 5 is provided on the transfer device 6, and the flexible material layer 5 directly contacts the release paper 2 and applies pressure to transfer the solid electrolyte membrane 1 to the negative electrode active layer 42, thereby completing the transfer process of the solid electrolyte membrane 1.

[0107] Comparative Application Example 1

[0108] This comparative example provides an all-solid-state battery. In the manufacturing method of the all-solid-state battery, a flexible material layer is not provided on the transfer device. The manufacturing method includes:

[0109] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, and place the solid electrolyte membrane on the active layer on one side of the positive electrode sheet with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0110] (2) using a transfer device to apply a pressure of 10 kN at 25° C. to transfer the solid electrolyte membrane to the active layer of the positive electrode sheet to obtain a composite positive electrode sheet;

[0111] (3) Assembling the composite positive electrode sheet described in step (2) and the corresponding uncomposite negative electrode sheet into an all-solid-state battery.

[0112] Application Comparative Example 2

[0113] This comparative example provides an all-solid-state battery. In a manufacturing method of the all-solid-state battery, hot pressing and cold pressing operations are not performed after transfer. The manufacturing method includes:

[0114] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, and place the solid electrolyte membrane on the active layer on one side of the positive electrode sheet with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0115] (2) a 3 mm thick silica gel is provided as a flexible material layer on the transfer device, and the flexible material layer is brought into contact with the release paper and the current collector of the positive electrode sheet and a pressure of 10 kN is applied at 25° C. to transfer the solid electrolyte membrane to the active layer of the positive electrode sheet to obtain a composite positive electrode sheet;

[0116] (3) Assembling the composite positive electrode sheet described in step (2) and the corresponding uncomposite negative electrode sheet into an all-solid-state battery.

[0117] Application Comparative Example 3

[0118] This comparative example provides an all-solid-state battery. In the manufacturing method of the all-solid-state battery, no flexible material layer is provided on the transfer device, and no hot pressing and cold pressing operations are performed after the transfer. The manufacturing method includes:

[0119] (1) Prepare a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane with release paper of the same size and specifications, and place the solid electrolyte membrane on the active layer on one side of the positive electrode sheet with the release paper facing outward; the solid electrolyte membrane is the solid electrolyte membrane obtained in Example 1;

[0120] (2) using a transfer device to apply a pressure of 10 kN at 25° C. to transfer the solid electrolyte membrane to the active layer of the positive electrode sheet to obtain a composite positive electrode sheet;

[0121] (3) Assembling the composite positive electrode sheet described in step (2) and the corresponding uncomposite negative electrode sheet into an all-solid-state battery.

[0122] The solid electrolyte membrane obtained in Example 1 was applied to Application Examples 1-4 and Comparative Examples 1-3 to prepare all-solid-state batteries, respectively. The lower limit of the charge and discharge cut-off voltage was set to 2 to 2.5 V, and the upper limit was set to 4 to 4.5 V. Charge and discharge tests were performed on each of the obtained all-solid-state batteries, and the results are shown in Table 2.

[0123] Table 2

[0124]

[0125]

[0126] It can be seen from Table 2 that: when using a flexible material layer for transfer and hot pressing and cold pressing, the solid electrolyte membrane obtained in Example 1 is applied to the single / double-side transfer of the positive electrode sheet or the single / double-side transfer of the negative electrode sheet to obtain an all-solid-state battery, which can obtain a higher first coulomb efficiency and capacity retention rate; compared with Application Example 1, in Application Comparative Example 1, no flexible material is used for transfer, so the thickness difference between the electrodes causes insufficient solid-solid interface contact and local overvoltage of the electrodes. The insufficient interface contact makes the coulomb efficiency lower and lithium dendrites are easily generated. The local overvoltage can cause damage to the electrode and produce a micro-short circuit phenomenon, which makes the capacity retention rate lower; Application Comparative Example 2 does not perform hot pressing and Cold pressing, so the flatness of the electrode after transfer is poor, there is local bending, and after lamination, the solid-solid interface contact is insufficient to a certain extent, so that the coulombic efficiency and capacity retention rate are low; in the application of comparative example 3, no flexible material is used for transfer and no hot pressing and cold pressing are performed, so the solid-solid interface contact is insufficient and the local overvoltage phenomenon is more serious, and the coulombic efficiency and capacity retention rate are worse; from the above, it can be seen that when using a flexible material layer for transfer and hot pressing and cold pressing, the solid-solid interface contact problem and the local overvoltage problem caused by the thickness difference between the electrodes of the all-solid-state battery can be improved, so that the battery can obtain a higher coulombic efficiency and capacity retention rate.

[0127] While the present invention is described through the above-described embodiments to illustrate the detailed structural features of the present invention, the present invention is not limited to these detailed structural features, nor does it necessarily rely on these detailed structural features for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0128] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0130] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for manufacturing an all-solid-state battery, characterized in that: The manufacturing method of the all-solid-state battery comprises the following steps: (1) preparing a positive electrode sheet, a negative electrode sheet, and a solid electrolyte membrane, respectively, wherein the solid electrolyte membrane has a release paper; placing the solid electrolyte membrane on the active layer of the positive electrode sheet or the negative electrode sheet, with the release paper facing outward; (2) providing a flexible material layer on a transfer device, and transferring the solid electrolyte membrane to the active layer of the positive electrode sheet or the negative electrode sheet by contacting the flexible material layer with the release paper and applying pressure, and then performing hot pressing and then cold pressing to obtain a composite positive electrode sheet or a composite negative electrode sheet; (3) assembling the composite positive electrode sheet or the composite negative electrode sheet of step (2) with the corresponding uncomposite negative electrode sheet or positive electrode sheet to form an all-solid-state battery; The solid electrolyte membrane includes a solid electrolyte, a binder and a plasticizer; based on 100 wt% of the mass of the solid electrolyte membrane, the mass of the plasticizer accounts for 0.1 wt% to 10 wt%.

2. The method for manufacturing an all-solid-state battery according to claim 1, wherein: Based on 100 wt% of the mass of the solid electrolyte membrane, the mass of the binder accounts for 0.5 wt% to 5 wt%.

3. The method for manufacturing an all-solid-state battery according to claim 1, wherein: Based on the mass of the solid electrolyte membrane being 100 wt%, the mass of the solid electrolyte accounts for 85 wt% to 99.4 wt%.

4. The method for manufacturing an all-solid-state battery according to claim 1, wherein: One side surface of the solid electrolyte membrane is covered with release paper for winding and storage or transfer processing.

5. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The thickness of the solid electrolyte membrane is 5 to 400 μm.

6. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The solid electrolyte includes a sulfide solid electrolyte.

7. The method for manufacturing an all-solid-state battery according to claim 6, wherein: The sulfide solid electrolyte includes any one of Li2S-GeS2, Li2S-P2S5 or Li2S-SiS2 or a combination of at least two thereof.

8. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The binder includes any one of polyvinylidene fluoride, styrene-butadiene rubber or organic olefinic acid or a combination of at least two thereof.

9. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The plasticizer includes diethyl phthalate and / or tributyl citrate.

10. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The preparation method of the solid electrolyte membrane includes: uniformly mixing a solid electrolyte, a binder, a plasticizer and a solvent, controlling the mass of the plasticizer to account for 0.1wt% to 10wt% of the total mass of the solid electrolyte, the binder and the plasticizer to prepare a solid electrolyte slurry, and heating and drying the solid electrolyte slurry after coating to obtain a solid electrolyte membrane.

11. The method for manufacturing an all-solid-state battery according to claim 10, wherein: The coating includes coating on the silicone oil side of the release paper.

12. The method for manufacturing an all-solid-state battery according to claim 10, wherein: The heating and drying is performed at a temperature of 80 to 110° C. and for a time of 2 to 5 hours.

13. The method for manufacturing an all-solid-state battery according to claim 10, wherein: The solvent includes any one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide or dimethyl sulfoxide, or a combination of at least two thereof.

14. The method for manufacturing an all-solid-state battery according to claim 1, wherein: In step (1), the specifications and sizes of the positive electrode sheet, the negative electrode sheet and the solid electrolyte membrane are the same.

15. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The release force of the release paper in step (1) is 3 to 60 g.

16. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The flexible material layer in step (2) includes silica gel and / or foam.

17. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The thickness of the flexible material layer in step (2) is 0.5 to 5 mm.

18. The method for manufacturing an all-solid-state battery according to claim 1, wherein: When the positive electrode sheet or the negative electrode sheet is provided with an active layer only on one side, the current collector of the positive electrode sheet or the negative electrode sheet contacts and applies pressure to the transfer device in step (2) through the flexible material layer.

19. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The transfer pressure in step (2) is 5 to 50 kN, and the temperature is 10 to 50°C.

20. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The hot pressing pressure in step (2) is 10 to 1000 N, and the temperature is 40 to 100° C.

21. The method for manufacturing an all-solid-state battery according to claim 1, wherein: The cold pressing pressure in step (2) is 10-1000N and the temperature is 0-25°C.

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