Multilayer composite tab, method for manufacturing the same, and all-solid-state battery
By employing a multi-layer composite electrode preparation method and utilizing simultaneous coating and multi-temperature gradient drying processes, the problem of increased interfacial transport impedance in all-solid-state batteries was solved, achieving high-efficiency and stable battery performance and production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHERY AUTOMOBILE CO LTD
- Filing Date
- 2026-01-28
- Publication Date
- 2026-06-05
AI Technical Summary
Existing methods for fabricating all-solid-state batteries lead to increased interfacial transport impedance, and there is a lack of effective solutions in current technologies.
A multilayer composite electrode preparation method is adopted, which involves simultaneously coating the active material slurry and the solid electrolyte slurry onto the surface of the current collector to form a composite wet electrode. Through processes such as multi-temperature gradient drying and hot rolling, the electrode layer and the electrolyte layer are tightly bonded, eliminating interfacial pores and gaps.
It significantly reduces interfacial ion transport impedance, improves electrode mechanical strength and battery performance consistency, simplifies the production process, and enhances production efficiency and yield.
Smart Images
Figure CN122158491A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of all-solid-state batteries, specifically to a multilayer composite electrode, its preparation method, and an all-solid-state battery. Background Technology
[0002] Conventional methods for fabricating sulfide all-solid-state batteries typically employ independent molding and stacking techniques to create positive and negative electrode layers and a sulfide electrolyte layer, followed by transfer and stacking. In these methods, the independent molding and stacking of the electrode and electrolyte layers leads to insufficient solid-solid interface contact, increasing the resistance to lithium-ion transport at the interface.
[0003] There is currently no good solution to the technical problem of increased interfacial transport impedance caused by existing solid-state battery fabrication methods. Summary of the Invention
[0004] This application provides a multilayer composite electrode, its preparation method, and an all-solid-state battery, to at least solve the technical problem that the preparation method of all-solid-state batteries in the prior art leads to an increase in interface transmission impedance.
[0005] According to one aspect of the embodiments of this application, a method for preparing a multilayer composite electrode is provided, comprising the following steps: Step S1, adding raw materials including an active material, a first solid electrolyte, a conductive agent and a first binder to an organic solvent and stirring to obtain an active material slurry; adding raw materials including a second solid electrolyte and a second binder to an organic solvent and stirring to obtain a solid electrolyte layer slurry; Step S2, simultaneously coating the active material slurry and the solid electrolyte layer slurry onto two opposing surfaces of a current collector to obtain a composite wet electrode consisting of an active material layer, a current collector and a solid electrolyte layer stacked sequentially; Step S3, drying the composite wet electrode to obtain a composite dry electrode; Step S4, sequentially rolling, die-cutting and drying the composite dry electrode to obtain a multilayer composite electrode.
[0006] Further, in step S3, the drying process includes a first-stage surface shaping treatment, a second-stage main body drying treatment, a third-stage deep drying treatment, and a fourth-stage cooling treatment performed sequentially. The first-stage surface shaping treatment is performed at a temperature of 50℃~70℃ for 5~10 minutes with a first wind speed. The second-stage main body drying treatment is performed at a temperature of 70℃~90℃ for 10~30 minutes with a second wind speed. The third-stage deep drying treatment is performed at a temperature of 80℃~100℃ for 20~30 minutes with a third wind speed. The fourth-stage cooling treatment involves cooling the electrode sheet after the third-stage deep drying treatment to below 50℃, wherein the first wind speed is greater than the second wind speed, and the second wind speed is greater than the third wind speed.
[0007] Furthermore, in step S4, the drying process includes a first drying stage and a second drying stage performed sequentially. The temperature of the first drying stage is 80℃~100℃ and the drying time is 12h. The process of the second drying stage is to cool the electrode sheet obtained in the first drying stage to below 40℃.
[0008] Further, in step S1, the mass ratio of the active material, the first solid electrolyte, the conductive agent, and the first binder is (60~80):(18~35):(0.1~3):(0.8~2); and / or, the mass ratio of the second solid electrolyte to the second binder is (90~99.5):(0.5~10); and / or, the first binder and the second binder are each independently selected from one or more of hydrogenated nitrile rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene-styrene block copolymer, polyisobutylene, polyurethane, and polyvinylidene fluoride; and / or, the conductive agent is selected from one or more of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, vapor-grown carbon fibers, graphene, and acetylene black; and / or, the first solid electrolyte and the second solid electrolyte are each independently selected from one or more of sulfides, halides, and oxides.
[0009] Furthermore, when the active material slurry is a positive electrode active material slurry and the solid electrolyte layer slurry is a positive electrode solid electrolyte layer slurry, the solid content of the positive electrode active material slurry and the positive electrode solid electrolyte layer slurry are each independently 60%~80%.
[0010] Furthermore, the positive electrode active material slurry includes a positive electrode active material, which is selected from one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and lithium cobalt oxide.
[0011] Furthermore, when the active material slurry is a negative electrode active material slurry and the solid electrolyte layer slurry is a negative electrode solid electrolyte layer slurry, the solid content of the negative electrode active material slurry and the negative electrode solid electrolyte layer slurry are each independently 40%~60%; and / or, the negative electrode active material slurry includes a negative electrode active material, which is selected from one or more of silicon carbide, silicon oxide, pure silicon and graphite.
[0012] Furthermore, in step S2, the active material layer and the solid electrolyte layer are each independently a single layer or multiple layers; and / or, the coating speed is 1~5 m / min.
[0013] According to another aspect of the embodiments of this application, a multilayer composite electrode is also provided, which is prepared by the above-described preparation method.
[0014] According to another aspect of the embodiments of this application, an all-solid-state battery is also provided, including a positive electrode and a negative electrode, wherein the positive electrode and / or the negative electrode are used as grids for the above-described multilayer composite electrode sheet, and / or the positive electrode and / or the negative electrode are prepared by the above-described preparation method.
[0015] In this embodiment, active material slurry and solid electrolyte slurry are simultaneously coated on two opposing surfaces of the current collector to form a composite wet electrode. This allows the electrode layer and electrolyte layer to achieve initial molecular-level contact in the liquid slurry state, promoting a tighter bond between the two slurry layers at the interface. The composite wet electrode is then dried to obtain a composite dry electrode, where the two slurry layers deform synergistically during drying and shrinkage, with particles interlocking to form a seamless, highly dense native interface in situ. This eliminates the porosity and gaps caused by insufficient physical contact in traditional stacking processes. Hot rolling and drying processes further strengthen the bond between the slurries, enhancing the mechanical strength of the electrode. Simultaneously, die-cutting ensures the consistency of electrode dimensions, facilitating subsequent battery encapsulation. The above preparation method improves the interfacial contact between the electrode layer and electrolyte layer, reduces interfacial ion transport impedance, and solves the technical problem of increased interfacial transport impedance caused by existing all-solid-state battery preparation methods. Attached Figure Description
[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:
[0017] Figure 1 This is a schematic diagram of the preparation method of the multilayer composite electrode in this application. Detailed Implementation
[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0020] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.
[0021] As analyzed in the background section, the existing methods for preparing all-solid-state batteries have the technical problem of increasing interfacial transport impedance. To solve this problem, the present invention provides a multilayer composite electrode, its preparation method, and an all-solid-state battery.
[0022] In one typical embodiment of this application, a method for preparing a multilayer composite electrode is provided, such as... Figure 1 As shown, it includes the following steps:
[0023] Step S1: Add raw materials including active material, first solid electrolyte, conductive agent and first binder to organic solvent and stir to obtain active material slurry; add raw materials including second solid electrolyte and second binder to organic solvent and stir to obtain solid electrolyte layer slurry.
[0024] Step S2: The active material slurry and the solid electrolyte layer slurry are simultaneously coated on the two opposite surfaces of the current collector to obtain a composite wet electrode sheet composed of an active material layer, a current collector, and a solid electrolyte layer stacked in sequence.
[0025] Step S3: Dry the composite wet electrode sheet to obtain the composite dry electrode sheet.
[0026] Step S4 involves sequentially rolling, die-cutting, and drying the composite dry electrode sheet to obtain a multilayer composite electrode sheet.
[0027] In this embodiment, active material slurry and solid electrolyte layer slurry are simultaneously coated on two opposing surfaces of the current collector to form a composite wet electrode. This allows the electrode layer and electrolyte layer to achieve initial molecular-level contact in the liquid slurry state, promoting a tighter bond between the two slurry layers at the interface. The composite wet electrode is then dried to obtain a composite dry electrode, where the two slurry layers deform synergistically during drying and shrinkage, with particles interlocking to form a seamless, highly dense native interface in situ. This eliminates the porosity and gaps caused by insufficient physical contact in traditional stacking processes. Hot rolling and drying processes further solidify the bond between the slurries, enhancing the mechanical strength of the electrode. Simultaneously, die-cutting ensures the consistency of electrode dimensions, facilitating subsequent battery encapsulation. The above preparation method improves the interfacial contact between the electrode layer and electrolyte layer, reduces interfacial ion transport impedance, and solves the technical problem of increased interfacial transport impedance caused by existing all-solid-state battery preparation methods.
[0028] Further, in step S3, the drying process includes a first-stage surface shaping treatment, a second-stage main body drying treatment, a third-stage deep drying treatment, and a fourth-stage cooling treatment performed sequentially. The first-stage surface shaping treatment is performed at a temperature of 50℃~70℃ for 5~10 minutes with a first wind speed. The second-stage main body drying treatment is performed at a temperature of 70℃~90℃ for 10~30 minutes with a second wind speed. The third-stage deep drying treatment is performed at a temperature of 80℃~100℃ for 20~30 minutes with a third wind speed. The fourth-stage cooling treatment involves cooling the electrode sheet after the third-stage deep drying treatment to below 50℃, wherein the first wind speed is greater than the second wind speed, and the second wind speed is greater than the third wind speed.
[0029] In the embodiments of this application, the first stage of surface shaping controls the temperature between 50°C and 70°C to promote the initial curing of the slurry surface, forming a stable protective layer to prevent particle scattering during subsequent drying. Simultaneously, a higher wind speed is used to quickly remove solvent vapor from the slurry surface, accelerating surface drying without causing rapid evaporation of internal solvents, thus avoiding surface crusting and ensuring uniform drying within the slurry. In the second stage of main drying, the temperature is increased to 70°C to 90°C to further accelerate solvent evaporation, promote particle bonding, and form a denser structure. A medium wind speed is used to remove solvent... The first stage involves drying the electrode at a temperature that is suitable for both the material and its internal structure, ensuring uniform shrinkage and compact packing without excessive impact on the internal structure. The second stage, involving the main drying process, involves raising the temperature to 80℃~100℃ and using low airflow to ensure complete evaporation of residual solvents within the electrode, while minimizing the temperature gradient between the surface and interior, thus preventing stress concentration due to temperature differences. The third stage, involving deep drying, cools the electrode to below 50℃ to prevent uneven shrinkage caused by rapid temperature drops, reducing defects such as cracks. The slow cooling rate also helps to gradually release internal stress, ensuring the structural integrity and interface quality of the electrode.
[0030] Furthermore, in step S4, the drying process includes a first drying stage and a second drying stage performed sequentially. The temperature of the first drying stage is 80℃~100℃ and the drying time is 12h. The process of the second drying stage is to cool the electrode sheet obtained in the first drying stage to below 40℃.
[0031] In the embodiments of this application, the first drying stage involves high-temperature drying to further remove any trace solvents that may remain in the electrode, ensuring that the electrode reaches its optimal dryness, improving its density and consistency, and reducing barriers to ion transport. The electrode obtained in the first drying stage is then slowly cooled to below 40°C, avoiding defects such as cracks and deformation caused by rapid temperature changes, thus improving production yield.
[0032] Further, in step S1, the mass ratio of the active material, the first solid electrolyte, the conductive agent, and the first binder is (60~80):(18~35):(0.1~3):(0.8~2). And / or, the mass ratio of the second solid electrolyte to the second binder is (90~99.5):(0.5~10); and / or, the first binder and the second binder are each independently selected from one or more of hydrogenated nitrile rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene-styrene block copolymer, polyisobutylene, polyurethane, and polyvinylidene fluoride; and / or, the conductive agent is selected from one or more of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, vapor-grown carbon fibers, graphene, and acetylene black; and / or, the first solid electrolyte and the second solid electrolyte are each independently selected from one or more of sulfides, halides, and oxides.
[0033] In the embodiments of this application, by strictly controlling the ratio of active material, solid electrolyte, conductive agent and binder, and selecting materials with specific functions, high performance and high stability of all-solid-state battery electrodes can be achieved. This not only optimizes the electrochemical performance of the electrode layer and electrolyte layer, but also improves the mechanical strength and production yield of the electrodes.
[0034] Furthermore, when the active material slurry is a positive electrode active material slurry and the solid electrolyte layer slurry is a positive electrode solid electrolyte layer slurry, the solid content of the positive electrode active material slurry and the positive electrode solid electrolyte layer slurry are each independently 60%~80%.
[0035] In the embodiments of this application, by controlling the solid content of the positive electrode active material slurry and the solid electrolyte layer slurry for the positive electrode, high filling density and continuous ion conduction paths of the electrode layer and electrolyte layer are ensured, thereby improving the energy density and rate performance of the battery. Reasonable solid content control not only improves the structural stability of the electrode sheet but also enhances the mechanical bonding between materials, increasing the overall mechanical strength of the composite electrode sheet and contributing to the long-term stable operation of the battery. The use of high-solid-content slurry helps to accelerate the production process, reduce drying time, and improve production yield by reducing deformation and defects. High-solid-content slurry helps to form a denser and more continuous interface between the electrode layer and the electrolyte layer, reducing interfacial impedance and improving the efficiency of electrochemical reactions.
[0036] Furthermore, the positive electrode active material slurry includes a positive electrode active material, which is selected from one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and lithium cobalt oxide.
[0037] Furthermore, when the active material slurry is a negative electrode active material slurry and the solid electrolyte layer slurry is a negative electrode solid electrolyte layer slurry, the solid content of the negative electrode active material slurry and the negative electrode solid electrolyte layer slurry are each independently 40%~60%; and / or, the negative electrode active material slurry includes a negative electrode active material, which is selected from one or more of silicon carbide, silicon oxide, pure silicon and graphite.
[0038] In the embodiments of this application, compared with the positive electrode material, the negative electrode material often requires a higher porosity to accommodate the volume expansion of lithium ions during the charging and discharging process. The negative electrode active material slurry and the negative electrode solid electrolyte layer slurry can maintain appropriate porosity within the solid content range of 40% to 60%, which not only ensures the effective storage of lithium ions, but also avoids the structural looseness and decrease in ion conduction efficiency caused by too low solid content.
[0039] Furthermore, in step S2, the active material layer and the solid electrolyte layer are each independently a single layer or multiple layers; and / or, the coating speed is 1~5 m / min.
[0040] In the embodiments of this application, by optimizing the number of active material layers and solid electrolyte layers and controlling the coating speed, it is helpful to improve battery performance, enhance production efficiency and increase design flexibility, providing key technical support for the high performance and large-scale production of all-solid-state batteries.
[0041] In another typical embodiment of this application, a multilayer composite electrode is also provided, which is prepared by the preparation method in the above embodiments.
[0042] In another typical embodiment of this application, an all-solid-state battery is also provided, including a positive electrode and a negative electrode, wherein the positive electrode and / or the negative electrode are grids of the multilayer composite electrode in the above embodiments, and / or the positive electrode and / or the negative electrode are prepared by the preparation method in the above embodiments.
[0043] The beneficial effects of this application will be explained below with reference to specific embodiments and comparative examples.
[0044] Example 1
[0045] Preparation of positive electrode slurry: The positive electrode active material (lithium nickel cobalt manganese oxide NCM811, D50=4μm), the first solid electrolyte (lithium indium chloride composite material Li3InCl6, D50=0.8μm), the binder (hydrogenated styrene-butadiene-styrene block copolymer SEBS) and the conductive agent (vertical graphite carbon fiber VGCF) were added to the tank at a mass ratio of 76:20:2:2. Xylene solvent was added, and the mixture was mixed by a vacuum stirrer at a speed of 2500 r / min for 4 min to obtain a uniformly stirred positive electrode slurry.
[0046] Preparation of electrolyte slurry: The second solid electrolyte (lithium phospho chalcogenide LPSC, D50=2μm) and binder (hydrogenated nitrile butadiene rubber HNBR) were added to the tank at a mass ratio of 96:4. Xylene solvent was added and mixed by vacuum stirring at a speed of 2500 r / min for 4 min to obtain a uniformly stirred electrolyte slurry.
[0047] Preparation of negative electrode slurry: The negative electrode active material (silicon carbon, D50=10.2μm), the first solid electrolyte (lithium phosphide chalcogenide compound LPSC, D50=2.3μm), the binder (hydrogenated nitrile rubber HNBR) and the conductive agent (vertical graphite carbon fiber VGCF) were added to the tank at a mass ratio of 63:33:1.5:2.5. Xylene solvent was added and mixed by vacuum stirring at a speed of 2500 r / min for 4 min to obtain a uniformly stirred negative electrode slurry.
[0048] Preparation of the electrolyte layer composite positive electrode P1: The positive electrode slurry and electrolyte slurry were transferred to the bottom coating tank and top coating tank of a slot extrusion double-layer simultaneous coating machine, respectively, for coating at a speed of 2 m / min. The flow ratio of the positive electrode slurry to the electrolyte slurry was 3, resulting in an electrolyte layer composite positive electrode wet sheet. The prepared electrolyte layer composite positive electrode wet sheet was dried: surface shaping treatment was carried out at 65°C and high wind speed for about 5 minutes to initially dry and shape the wet sheet; body drying treatment was carried out at 70°C and medium wind speed for about 30 minutes to remove most of the solvent from the wet sheet; deep drying treatment was carried out at 100°C and low wind speed for about 30 minutes to remove the residual solvent from the wet sheet; cooling treatment was carried out by slowly cooling to below 50°C to obtain the dried electrolyte layer composite positive electrode sheet. The electrolyte layer composite positive electrode sheet was hot rolled and die-cut, then transferred into a nitrogen oven for further drying. The temperature was slowly raised to 80℃~100℃ and dried for 12 hours under low wind speed conditions. After that, the temperature was slowly lowered to below 40℃ to prepare the electrolyte layer composite positive electrode sheet P1.
[0049] Preparation of the electrolyte layer composite negative electrode N1: The negative electrode slurry and electrolyte slurry were transferred to the bottom coating tank and top coating tank of a slot extrusion double-layer simultaneous coating machine, respectively, for coating at a speed of 2 m / min. The flow ratio of the negative electrode slurry to the electrolyte slurry was 2. The prepared electrolyte layer composite positive electrode wet electrode was dried: surface shaping treatment was carried out at 65°C and high wind speed for about 5 min to preliminarily dry and shape the wet electrode; main body drying treatment was carried out at 70°C and medium wind speed for about 30 min to remove most of the solvent from the wet electrode; deep drying treatment was carried out at 100°C and low wind speed for about 30 min to remove the residual solvent from the wet electrode; cooling treatment was carried out by slowly cooling to below 50°C to obtain the dried electrolyte layer composite negative electrode. The electrolyte layer composite negative electrode sheet was hot rolled and die-cut, then transferred into a nitrogen oven for further drying. The temperature was slowly raised to 80℃~100℃ and maintained at low wind speed for 12 hours. After that, the temperature was slowly lowered to below 40℃ to prepare the electrolyte layer composite negative electrode sheet N1.
[0050] Preparation of ordinary composite positive electrode sheet: The positive electrode slurry is coated into a single-layer electrode sheet by the bottom coating die of a slit extrusion double-layer simultaneous coating machine, dried, rolled, cut, and dried again to obtain ordinary composite positive electrode sheet P2. The electrolyte slurry is coated into a single-layer electrolyte sheet by the bottom coating die of a slit extrusion double-layer simultaneous coating machine and dried; the electrolyte sheet is transferred onto the single-layer positive electrode sheet and cut to obtain ordinary composite positive electrode sheet P3;
[0051] Preparation of ordinary composite negative electrode sheet: The negative electrode slurry is coated into a single-layer negative electrode sheet by the bottom coating die of a slit extrusion double-layer simultaneous coating machine, dried, rolled, cut, and dried again to obtain ordinary composite negative electrode sheet N2; the electrolyte slurry is coated into a single-layer electrolyte sheet by the bottom coating die of a slit extrusion double-layer simultaneous coating machine and dried; the electrolyte sheet is transferred onto the single-layer negative electrode sheet and cut to obtain ordinary composite negative electrode sheet N3.
[0052] Electrolyte layer composite positive electrode P1 and electrolyte layer composite negative electrode N1 are stacked and packaged to prepare a small soft-pack battery cell.
[0053] Example 2
[0054] The difference between Example 2 and Example 1 is that the electrolyte layer composite negative electrode N1 and ordinary composite positive electrode P2 are stacked and packaged to prepare a small soft-pack battery cell.
[0055] Comparative Example 1
[0056] The difference between Comparative Example 1 and Example 1 is that ordinary composite positive electrode P2 and ordinary composite negative electrode N3 are stacked and packaged to prepare a small soft-pack battery cell.
[0057] Comparative Example 2
[0058] The difference between Comparative Example 2 and Example 1 is that ordinary composite positive electrode P3 and ordinary composite negative electrode N3 are stacked and packaged to prepare a small soft-pack battery cell.
[0059] Comparative Example 3
[0060] The difference between Comparative Example 3 and Example 1 is that ordinary composite positive electrode P3 and ordinary composite negative electrode N2 are stacked and packaged to prepare a small soft-pack battery cell.
[0061] The compaction density, coating time, and cell yield of the small soft-pack battery cells obtained in Examples 1 to 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were compared respectively, and the comparison results are shown in Table 1.
[0062] Table 1
[0063]
[0064] As can be seen from Table 1, the compaction of the electrode sheets proposed in the embodiments of this application is higher than that of ordinary single-layer electrode sheets, which effectively improves the contact area of the electrode and the packing density between particles. At the same time, the double-layer coating technology can significantly shorten the process time, increase production efficiency by 27%, and increase cell yield by 20%.
[0065] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:
[0066] 1. This invention achieves initial molecular-level contact between the electrode layer and the electrolyte layer in a liquid slurry state through synchronous coating. Subsequently, guided by a multi-temperature gradient drying process, the two layers deform synergistically during drying shrinkage, interlocking between particles to form a seamless, highly dense native interface in situ. This fundamentally eliminates the porosity and gaps caused by insufficient physical contact in traditional stacking processes, significantly reducing the interfacial ion transport impedance to less than one-tenth of that of traditional methods.
[0067] 2. Because the two layers of slurry come into contact in a wet state and undergo the drying and curing process together, a strong interlocking structure and a mutually diffused network of binder molecular chains are formed at their interface. This makes the bonding force between the two layers much higher than the physical bonding force of subsequent lamination. The prepared electrode sheet has extremely high interlayer peel strength, which can effectively resist the stress generated during subsequent slitting, winding and cycling processes, and eliminate the risk of interlayer separation.
[0068] 3. Simultaneous coating and integrated drying combine multiple processes into one step, greatly reducing the number of production steps and electrode handling and alignment operations, thus avoiding damage, misalignment, and contamination caused by multiple processing steps. The electrode interface uniformity and overall consistency produced by this process are far superior to those of samples prepared sequentially, thereby significantly improving the production yield and performance consistency of all-solid-state batteries.
[0069] 4. The multi-temperature gradient drying process of this invention achieves programmed solvent removal through the coordinated control of "preliminary shaping → main body evaporation → deep drying → stress relaxation". This strategy ensures that the interface region is dried last, using continuous capillary force to keep the two layers of particles close together, while allowing internal stress to be gradually released under gentle conditions. This perfectly solves the manufacturing problems such as electrode curling and cracking, and obtains flat, defect-free electrodes.
[0070] 5. By combining the key steps of electrode fabrication and battery integration (stacking) into one, the process flow is simplified and production time is shortened. Furthermore, this technology is highly compatible with existing slot extrusion coating equipment, requiring only an upgrade to the drying system. The equipment modification cost is low, making it ideal for large-scale roll-to-roll continuous production, providing an efficient and economical technological path for the rapid industrialization of all-solid-state batteries.
[0071] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.
[0072] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.
[0073] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a multilayer composite electrode, characterized in that, Includes the following steps: Step S1: Add raw materials including active material, first solid electrolyte, conductive agent and first binder to organic solvent and stir to obtain active material slurry; add raw materials including second solid electrolyte and second binder to organic solvent and stir to obtain solid electrolyte layer slurry; Step S2: The active material slurry and the solid electrolyte layer slurry are simultaneously coated on the two opposite surfaces of the current collector to obtain a composite wet electrode sheet composed of the active material layer, the current collector and the solid electrolyte layer stacked in sequence. Step S3: Dry the composite wet electrode sheet to obtain a composite dry electrode sheet; Step S4: The composite dry electrode sheet is sequentially subjected to rolling, die-cutting and drying processes to obtain a multilayer composite electrode sheet.
2. The preparation method according to claim 1, characterized in that, In step S3, the drying process includes a first-stage surface shaping treatment, a second-stage main body drying treatment, a third-stage deep drying treatment, and a fourth-stage cooling treatment performed sequentially. The first-stage surface shaping treatment is performed at a temperature of 50℃~70℃ for 5~10 minutes with a first wind speed. The second-stage main body drying treatment is performed at a temperature of 70℃~90℃ for 10~30 minutes with a second wind speed. The third-stage deep drying treatment is performed at a temperature of 80℃~100℃ for 20~30 minutes with a third wind speed. The fourth-stage cooling treatment involves cooling the electrode sheet after the third-stage deep drying treatment to below 50℃, wherein the first wind speed is greater than the second wind speed, and the second wind speed is greater than the third wind speed.
3. The preparation method according to claim 1, characterized in that, In step S4, the drying process includes a first drying stage and a second drying stage performed sequentially. The temperature of the first drying stage is 80℃~100℃ and the drying time is 12h. The process of the second drying stage is to cool the electrode sheet obtained in the first drying stage to below 40℃.
4. The preparation method according to any one of claims 1-3, characterized in that, In step S1, the mass ratio of the active material, the first solid electrolyte, the conductive agent, and the first binder is (60~80):(18~35):(0.1~3):(0.8~2); and / or, the mass ratio of the second solid electrolyte to the second binder is (90~99.5):(0.5~10); and / or, the first binder and the second binder are each independently selected from one or more of hydrogenated nitrile rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene-styrene block copolymer, polyisobutylene, polyurethane, and polyvinylidene fluoride; and / or, the conductive agent is selected from one or more of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, vapor-grown carbon fibers, graphene, and acetylene black; and / or, the first solid electrolyte and the second solid electrolyte are each independently selected from one or more of sulfides, halides, and oxides.
5. The preparation method according to any one of claims 1-3, characterized in that, When the active material slurry is a positive electrode active material slurry and the solid electrolyte layer slurry is a positive electrode solid electrolyte layer slurry, the solid content of the positive electrode active material slurry and the positive electrode solid electrolyte layer slurry are each independently 60%~80%.
6. The preparation method according to claim 5, characterized in that, The positive electrode active material slurry includes a positive electrode active substance, which is selected from one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and lithium cobalt oxide.
7. The preparation method according to any one of claims 1-3, characterized in that, When the active material slurry is a negative electrode active material slurry and the solid electrolyte layer slurry is a negative electrode solid electrolyte layer slurry, the solid content of the negative electrode active material slurry and the negative electrode solid electrolyte layer slurry are each independently 40%~60%; and / or, the negative electrode active material slurry includes a negative electrode active substance, which is selected from one or more of silicon carbide, silicon oxide, pure silicon and graphite.
8. The preparation method according to any one of claims 1-3, characterized in that, In step S2, the active material layer and the solid electrolyte layer are each independently a single layer or multiple layers; and / or, the coating speed is 1~5m / min.
9. A multilayer composite electrode, characterized in that, The multilayer composite electrode is prepared by the preparation method described in any one of claims 1-8.
10. An all-solid-state battery, comprising a positive electrode and a negative electrode, characterized in that, The positive electrode and / or the negative electrode are the multilayer composite electrodes according to claim 9, and / or the positive electrode and / or the negative electrode are prepared by the preparation method according to any one of claims 1-8.