An extrusion flat sheet coating apparatus for preparing a solid-state electrolyte membrane

Abstract

The utility model relates to the technical field of preparation electrolyte membrane, especially a kind of extrusion flat plate coating equipment for preparing solid electrolyte membrane, including equipment main body, equipment main body is equipped with slurry supply unit, extrusion coating unit, gauge control system, multistage drying unit and peeling and winding unit, slurry supply unit is set to one side of extrusion coating unit, the screw pump of slurry supply unit is communicated with the coating die of extrusion coating unit, multistage drying unit is set to the discharge side of extrusion coating unit, the gauge probe of gauge control system is set in multistage drying unit inside, peeling and winding unit is set to the discharge side of multistage drying unit.The utility model can realize the continuous, efficient, stable production of solid electrolyte membrane, the prepared membrane piece uniformity, no defect, high density, and excellent mechanical property.

Description

Technical Field

[0001] This utility model relates to the field of electrolyte membrane preparation technology, and in particular to an extrusion plate coating device for preparing solid electrolyte membranes. Background Technology

[0002] Solid-state lithium batteries are considered the core of next-generation energy storage devices due to their high energy density and high safety. As a core component, the performance of the solid electrolyte membrane (such as ionic conductivity, mechanical strength, and thickness uniformity) directly determines the overall performance of the battery.

[0003] Currently, the mainstream methods for preparing solid electrolyte membranes include casting, hot pressing, and electrospinning. Casting is simple, but the resulting membranes are typically thick, prone to pores and cracks due to solvent evaporation, have poor mechanical strength, and exhibit high drying shrinkage, affecting dimensional stability. Hot pressing can produce dense electrolyte membranes, but it is energy-intensive, requires strict control over the particle size and distribution of the powder raw materials, and is difficult to use for large-area ultrathin films. Electrospinning can produce porous membranes, but the membrane strength is low, the process is complex, and yields are low, making industrial application difficult.

[0004] Extrusion plate coating is an advanced pre-quantity coating technology that precisely controls the thickness and width of the wet film by forming a stable slurry bead between two parallel coating heads and extruding it onto a moving substrate. While this method has been applied in electrode fabrication, a mature and optimized solution is still lacking for the fabrication of solid electrolyte membranes, which require extremely high uniformity and density. In particular, addressing the stable delivery and coating of high-solids-content, high-viscosity slurries, as well as stress release during subsequent drying, are key challenges for achieving mass production of high-quality solid electrolyte membranes.

[0005] Therefore, there is an urgent need to develop a method and supporting equipment for preparing solid electrolyte membranes based on extrusion flat plate coating technology, which can be continuously produced and can precisely control the thickness and uniformity of the membrane layer. Utility Model Content

[0006] The purpose of this invention is to provide an extrusion plate coating device for preparing solid electrolyte membranes, which can realize continuous, efficient and stable production of solid electrolyte membranes. The prepared membranes have uniform thickness, no defects, high density and excellent mechanical properties.

[0007] To achieve the above objectives, this utility model provides an extrusion plate coating device for preparing solid electrolyte membranes, comprising a main body, on which are provided a slurry supply unit, an extrusion coating unit, a thickness measurement control system, a multi-stage drying unit, and a peeling and winding unit. The slurry supply unit is located on one side of the extrusion coating unit, and the screw pump of the slurry supply unit is connected to the coating die of the extrusion coating unit. The multi-stage drying unit is located on the discharge side of the extrusion coating unit. The thickness measurement probe of the thickness measurement control system is located inside the multi-stage drying unit. The peeling and winding unit is located on the discharge side of the multi-stage drying unit.

[0008] Preferably, the slurry supply unit includes a slurry storage tank and a screw pump. The screw pump is located at the bottom of the slurry storage tank, the inlet of the screw pump is connected to the outlet of the slurry storage tank, and the outlet of the screw pump is connected to the inner cavity of the coating die head through a slurry delivery pipe.

[0009] Preferably, the extrusion coating unit includes a coating die, a fixed base, a support base, and a moving component. Two fixed bases are symmetrically arranged, and the two fixed bases are respectively fixedly connected to the main body of the equipment. The support base is connected to the upper side of the two fixed bases through the moving component, and the coating die is fixedly connected to the upper side of the support base. The moving component includes a fixed block, a sliding block, a slide rail, and a telescopic cylinder. The fixed block is fixedly connected to the upper side of the fixed base, the sliding block is fixedly connected to the lower side of the support base, the sliding block and the fixed block are connected by the slide rail, and the telescopic cylinder is disposed between the fixed bases. One end of the telescopic cylinder is fixedly connected to the main body of the equipment, and the other end of the telescopic cylinder is fixedly connected to the support base.

[0010] Preferably, the coating die head includes an upper die head and a lower die head, with a coating slit provided between the upper and lower die heads. The upper and lower die heads form a die head lip on the discharge side of the coating slit. The rear sides of the upper and lower die heads are connected by a hinge, with a handle on the upper side of the hinge. A material storage chamber is provided in the middle of the lower die head, and a connecting pipe connected to a slurry conveying pipe is provided on the rear side of the lower die head. Both the connecting pipe and the coating slit are connected to the material storage chamber. An adjustment component for adjusting the gap of the coating slit is provided on the upper die head.

[0011] Preferably, the thickness measurement control system includes a control box and an online thickness measurement mechanism. The control box is equipped with a central processing unit with data processing and closed-loop control algorithms. The online thickness measurement mechanism, slurry supply unit, extrusion coating unit, multi-stage drying unit, and peeling and winding unit are all electrically connected to the control box. The online thickness measurement mechanism includes several thickness measurement probes, which are beta-ray thickness gauges or infrared thickness gauges.

[0012] Preferably, the multi-stage drying unit includes a segmented drying chamber, with several parallel conveyor rollers inside the drying chamber, and a thickness measuring probe is installed on the side wall of the drying chamber and is flush with the height of the conveyor rollers.

[0013] Preferably, the peeling and winding unit includes a peeling roller, an electrolyte membrane winding roller, and a base film winding roller. The peeling roller is located on one side of the discharge port of the multi-stage drying unit, and the electrolyte membrane winding roller and the base film winding roller are located below the multi-stage drying unit and inside the main body of the equipment.

[0014] A method for preparing a solid electrolyte membrane, using the above-mentioned extrusion plate coating equipment for preparing solid electrolyte membranes, includes the following steps: S1. Mix solid electrolyte powder, binder, electrolyte salt and solvent, and after high-speed stirring and vacuum degassing, prepare a uniform slurry with a solid content of 40%-70% and a viscosity in the range of 1000-50000mPa•s. Load the prepared slurry into the slurry supply unit. S2. Load the base film onto the unwinding roller, thread the base film through the tension roller and transport it to the coating back roller, apply constant tension through the tension control mechanism, install and clean the coating die head, set the gap between the die head lip and the substrate to the target value by adjusting the moving component, and preheat the drying oven to the preset temperature gradient. S3. The slurry supply unit delivers the slurry obtained in S1 to the extrusion coating die head at a constant flow rate. The slurry is extruded from the die head lip, forming a stable slurry bead between the die head lip and the substrate. The base film moves at a uniform speed under the support of the coating back roller, extruding and extending the slurry bead into a continuous and uniform wet film. By adjusting the slurry delivery rate, the base film moving speed, and the gap between the die head lip and the substrate, wet films of different thicknesses can be prepared. S4. The base film coated with wet film enters the drying oven for step drying and curing; S5. The completely dried and cured solid electrolyte membrane is taken out of the drying box and peeled off from the base film by the peeling roller. The peeled solid electrolyte membrane is then wound up by the electrolyte membrane winding roller, while the peeled base film is recycled by the base film winding roller. Finally, a solid electrolyte membrane roll with a thickness of 5-100μm, a thickness tolerance within ±3%, a smooth surface, and no macroscopic defects is obtained.

[0015] Preferably, in S1, the solid electrolyte powder includes one of lithium lanthanum zirconium oxide (LLZO), tantalum-doped lithium lanthanum zirconium oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), lithium phosphorus sulfide chloride (LPSCl), argyrodite, and polyethylene oxide (PEO). The binder includes one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), styrene-butadiene rubber (SBR), and polyacrylonitrile (PAN); Electrolyte salts include lithium perchlorate (LiClO4); The solvent includes one of xylene, N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF).

[0016] Preferably, in S4, the step-by-step drying is carried out in a closed environment and includes at least three stages: the first stage drying temperature is 40-60℃ and the drying wind speed is 1.0m / s; the second stage drying temperature is 60-80℃ and the drying wind speed is 2.0m / s; and the third stage drying temperature is 80-100℃ and the drying wind speed is 3.0m / s.

[0017] Therefore, the present invention employs the above-mentioned extrusion plate coating equipment for preparing solid electrolyte membranes, which has the following beneficial effects: (1) The extrusion plate coating equipment of this utility model adopts a pre-quantity coating method, and the film thickness is precisely determined by the slurry flow rate, coating speed and slurry concentration. Compared with traditional non-pre-quantity methods such as doctor blade coating, it has extremely high precision and consistency. By precisely controlling the flow rate of the screw pump and using high-precision adjustment components to control the gap between the die lip and the substrate, combined with stable coating speed control, the film thickness tolerance can be controlled within ±3%, which is far superior to traditional methods such as doctor blade coating. It can meet the stringent requirements of high-performance solid-state batteries for film thickness uniformity and effectively improve the overall performance and production stability of the battery.

[0018] (2) By utilizing a slit-type coating die and stable slurry beads, this invention can produce a solid electrolyte membrane with an extremely smooth surface, free of scratches and pinholes. The slit-type coating die of this invention enables the slurry to form stable slurry beads between the die lip and the substrate. During the uniform movement of the base film, the slurry beads are evenly squeezed and stretched into a film, avoiding the generation of scratches and pinholes. The surface roughness Ra of the prepared membrane can reach 0.1-0.5μm, providing a high-quality electrolyte membrane for solid-state batteries and effectively improving the performance and reliability of the battery.

[0019] (3) By adjusting the slurry formulation and process parameters, this utility model can be widely applied to the solid electrolyte film formation of various systems such as oxides, sulfides, and polymers. By optimizing the slurry formulation, selecting appropriate binders and solvents, and precisely controlling process parameters such as coating speed, drying temperature and wind speed, high-quality film formation of solid electrolytes of various systems can be successfully achieved, providing strong support for the diversified development of solid battery technology and meeting the needs of different application scenarios for solid electrolyte films.

[0020] (4) By adjusting the gap between the die lip and the substrate and the solid content of the slurry, this utility model can stably prepare an ultra-thin solid electrolyte membrane of less than 10 μm, thereby achieving the ultra-thinning of the electrolyte membrane.

[0021] (5) The preparation method of this utility model is suitable for roll-to-roll continuous production, which is highly efficient and low-cost. In the roll-to-roll continuous production process, the base film can be coated, dried and wound up without interruption, which greatly improves the production efficiency compared with the traditional intermittent production method. Moreover, continuous production reduces the number of start-ups and shutdowns in the production process, reduces energy consumption and equipment wear, and thus effectively reduces production costs. At the same time, the equipment of this utility model can be further integrated with electrode coating equipment to realize the integrated preparation of solid-state batteries, such as directly coating the electrolyte layer on the anode, reducing intermediate processes and material losses, further improving production efficiency and reducing costs, and laying a solid foundation for the large-scale industrial production of solid-state batteries.

[0022] (6) This utility model effectively avoids problems such as surface skinning, cracking and internal pores caused by rapid solvent evaporation through a multi-stage gradient drying process, thereby improving the density and mechanical integrity of the film.

[0023] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an extrusion plate coating device for preparing solid electrolyte membranes according to the present invention; Figure 2 This is a schematic diagram of the coating unit of this utility model; Figure 3 This is a cross-sectional view of the coating die head of this utility model; Figure 4 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 2 of this utility model. Figure 4 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 4 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 5 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 3 of this utility model. Figure 5 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 5 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 6 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 4 of this utility model. Figure 6 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 6 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 7 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 5 of this utility model. Figure 7 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 7 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 8 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 6 of this utility model. Figure 8 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 8 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 9 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 7 of this utility model. Figure 9 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 9 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 10 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 8 of this utility model. Figure 10 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 10 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 11 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 9 of this utility model. Figure 11 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 11 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 12 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared in Embodiment 10 of this utility model. Figure 12 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 12 In the diagram, b represents the discharge specific capacity after 100 cycles. Figure 13 This is a combined diagram of the discharge specific capacity of the solid electrolyte membrane prepared according to the comparative example of this invention. Figure 13 In the diagram, 'a' represents the specific capacity of the first discharge cycle. Figure 13 In the diagram, b represents the discharge specific capacity after 100 cycles.

[0025] Figure label: 1. Main body of the equipment; 2. Slurry supply unit; 21. Slurry storage tank; 22. Screw pump; 3. Extrusion coating unit; 31. Coating die head; 311. Upper die head; 312. Lower die head; 313. Coating slit; 314. Die head lip; 315. Hinge; 316. Handle; 317. Material storage chamber; 318. Connecting pipe; 319. Adjustment assembly; 32. Fixed base; 33. Support base; 34. Moving component; 341. Fixed block; 342. Sliding block; 343. Telescopic cylinder; 4. Thickness measurement control system; 41. Control box; 42. Thickness probe; 5. Multi-stage drying unit; 51. Drying box; 52. Conveyor roller; 6. Peeling and winding unit; 61. Peeling roller; 62. Electrolyte membrane winding roller; 63. Base film winding roller; 7. Unwinding roller; 8. Tension roller; 9. Coating back roller. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate this invention and are not intended to limit the scope of this invention.

[0027] Example 1 like Figure 1-3 As shown, this utility model provides an extrusion plate coating device for preparing solid electrolyte membranes, including a main body 1. The main body 1 is equipped with a slurry supply unit 2, an extrusion coating unit 3, a thickness measurement control system 4, a multi-stage drying unit 5, and a peeling and winding unit 6. The slurry supply unit 2 is located on one side of the extrusion coating unit 3, and the screw pump 22 of the slurry supply unit 2 is connected to the coating die 31 of the extrusion coating unit 3 for storing and transporting slurry. The multi-stage drying unit 5 is located on the discharge side of the extrusion coating unit 3, and the thickness measurement probe 42 of the thickness measurement control system 4 is located inside the multi-stage drying unit 5. The peeling and winding unit 6 is located on the discharge side of the multi-stage drying unit 5. The overall structure is compact and the units work together effectively.

[0028] The slurry supply unit 2 includes a slurry storage tank 21 and a screw pump 22. The slurry storage tank 21 is made of corrosion-resistant materials available in the prior art, ensuring the safe storage of various solid electrolyte slurries. It is equipped with an internal stirring device to prevent sedimentation or stratification during storage, maintaining the uniformity of the slurry. The screw pump 22 is located at the bottom of the slurry storage tank 21. The inlet of the screw pump 22 is connected to the outlet of the slurry storage tank 21, and the outlet of the screw pump 22 is connected to the inner cavity of the coating die head 31 via a slurry delivery pipe. The screw pump 22 can precisely control the slurry flow rate, with a flow control accuracy of ±0.1 mL / min, providing a stable slurry supply for subsequent coating operations.

[0029] The extrusion coating unit 3 includes a coating die 31, a fixed base 32, a support base 33, and a moving component 34. Two fixed bases 32 are symmetrically arranged and are fixedly connected to the main body 1 of the equipment, providing reliable support for the entire extrusion coating unit 3. The support base 33 is connected to the upper side of the two fixed bases 32 through the moving component 34. The coating die 31 is fixedly connected to the upper side of the support base 33. By adjusting the moving component 34, the gap between the coating die 31 and the coating back roller 9 can be precisely adjusted.

[0030] The moving component 34 includes a fixed block 341, a sliding block 342, a slide rail, and a telescopic cylinder 343. The fixed block 341 is fixedly connected to the upper side of the fixed base 32, and the sliding block 342 is fixedly connected to the lower side of the support base 33. The sliding block 342 and the fixed block 341 are connected by a slide rail, which is a high-precision slide rail in the prior art. Through the cooperation of the sliding block 342, the fixed block 341, and the slide rail, the support base 33 can slide smoothly on the fixed base 32, ensuring the accuracy and stability of the coating die head 31 during the movement process.

[0031] Telescopic cylinder 343 is installed between fixed seats 32. One end of telescopic cylinder 343 is fixedly connected to the main body 1 of the equipment, and the other end of telescopic cylinder 343 is fixedly connected to the support seat 33. Through the telescopic movement of telescopic cylinder 343, the position of support seat 33 can be precisely adjusted, thereby adjusting the position of coating die head 31. The position adjustment accuracy can reach ±0.01mm.

[0032] The coating die 31 includes an upper die 311 and a lower die 312. A coating slit 313 is provided between the upper die 311 and the lower die 312. The upper die 311 and the lower die 312 form a die lip 314 on the discharge side of the coating slit 313. The rear sides of the upper die 311 and the lower die 312 are connected by a hinge 315. A handle 316 is provided on the upper side of the hinge 315 to facilitate the operator to open and close the coating die 31 for cleaning or maintenance. A material storage chamber 317 is provided in the middle of the lower die 312. A connecting pipe 318 connected to the slurry conveying pipe is provided on the rear side of the lower die 312. Both the connecting pipe 318 and the coating slit 313 are connected to the material storage chamber 317 to ensure that the slurry can smoothly enter the material storage chamber 317 and be extruded through the coating slit 313. The upper die head 311 is provided with an adjustment component 319 for adjusting the gap of the coating slit 313. The adjustment component 319 can be a micrometer adjustment component 319 in the prior art, which can accurately adjust the gap of the coating slit 313 to meet the preparation requirements of solid electrolyte membranes of different thicknesses.

[0033] The thickness measurement control system 4 includes a control box 41 and an online thickness measurement mechanism. The control box 41 is equipped with a central processing unit that is equipped with data processing and closed-loop control algorithms in the prior art. It can quickly and accurately process the data from the online thickness measurement mechanism and adjust the working parameters of the slurry supply unit 2, the extrusion coating unit 3, etc. in real time according to the preset film thickness parameters to realize real-time closed-loop control of film thickness.

[0034] The online thickness measurement mechanism includes several thickness probes 42, which employ non-contact beta-ray thickness gauges or infrared thickness gauges. Beta-ray thickness gauges utilize the attenuation characteristics of beta rays penetrating materials to measure film thickness, offering advantages such as high measurement accuracy and fast response speed, with a measurement accuracy of ±0.1μm. Infrared thickness gauges determine film thickness by measuring the reflection and refraction of infrared light within the film, offering advantages such as non-contact measurement and no damage to the film, with a similar measurement accuracy of ±0.1μm. The online thickness measurement mechanism, slurry supply unit 2, extrusion coating unit 3, multi-stage drying unit 5, and peeling and winding unit 6 are all electrically connected to the control box 41, enabling intelligent control and collaborative operation of the entire equipment.

[0035] The multi-stage drying unit 5 includes a segmented drying chamber 51. Inside the drying chamber 51 are several parallel conveyor rollers 52 for smoothly conveying the base film coated with a wet film. A thickness probe 42 is mounted on the side wall of the drying chamber 51 and is flush with the height of the conveyor rollers 52, enabling real-time monitoring of film thickness changes during the drying process. The drying chamber 51 contains air ducts, heating elements, and ventilation devices, allowing for precise control of drying temperature and airflow. During the drying process, the drying temperature and airflow can be flexibly adjusted according to different drying stages and film characteristics to ensure uniform and rapid drying and curing of the film.

[0036] The peeling and winding unit 6 is used to peel and wind up the dried and cured solid electrolyte membrane from the base film. It includes a peeling roller 61, an electrolyte membrane winding roller 62, and a base film winding roller 63. The peeling roller 61 is located on the discharge side of the multi-stage drying unit 5. The peeling roller 61 is existing technology and has appropriate friction on its surface, enabling it to smoothly peel the solid electrolyte membrane from the base film without damaging it. The electrolyte membrane winding roller 62 and the base film winding roller 63 are located below the multi-stage drying unit 5 and within the main body 1 of the equipment, making the overall structure of the equipment compact and reducing its floor space.

[0037] Example 2 A method for preparing a solid electrolyte membrane, using the extrusion plate coating equipment used in Example 1, includes the following steps: S1. Dissolve 4g of tantalum-doped lithium lanthanum zirconium oxide (LLZTO) powder, 28g of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), 12g of polyacrylonitrile (PAN) binder, and 12g of lithium perchlorate (LiClO4) in 240g of N,N-dimethylformamide (DMF) solvent. Stir the mixture in a vacuum mixer at 3000r / min for 4 hours to ensure thorough and uniform mixing. Then, place the mixed slurry into a vacuum degassing device and degas it at a vacuum of 0.1MPa for 1.0 hour to remove air bubbles, obtaining a uniform slurry with a solid content of 76% and a viscosity of 1500mPa•s. The obtained slurry is then stored in slurry storage tank 21 of slurry supply unit 2 for later use.

[0038] S2. Load the PET base film onto the unwind roller 7, thread the base film through the tension roller 8, and convey it to the coating back roller 9. Apply constant tension through the tension control mechanism. Install and clean the coating die 31. Set the gap between the die lip 314 and the substrate to 200μm by adjusting the moving component 34. Set the coating speed to 5mm / s. Control the slurry delivery rate to 1mm / s by the screw pump 22. Preheat the drying oven 51 to the preset temperature gradient. Set the three temperature zones of the drying oven 51 to 50℃, 70℃, and 80℃, respectively.

[0039] S3, the slurry supply unit 2 delivers the slurry obtained in S1 to the extrusion coating die head 31 at a constant flow rate. The slurry is extruded from the die head lip 314, forming stable slurry beads between the die head lip 314 and the substrate. The base film moves at a uniform speed under the support of the coating back roller 9, extruding and extending the slurry beads into a continuous and uniform wet film.

[0040] When a thinner wet film needs to be prepared, the slurry delivery rate can be appropriately reduced, the base film moving speed can be increased, and the gap between the die lip 314 and the substrate can be reduced. Conversely, when a thicker wet film needs to be prepared, the slurry delivery rate can be increased, the base film moving speed can be reduced, and the gap between the die lip 314 and the substrate can be increased.

[0041] S4. The base film coated with wet film enters the drying oven 51 for step drying and curing. The step drying is carried out in a closed environment and includes at least three stages: the first stage drying temperature is 50℃ and the drying wind speed is 1.0m / s, the second stage drying temperature is 70℃ and the drying wind speed is 2.0m / s, and the third stage drying temperature is 80℃ and the drying wind speed is 3.0m / s.

[0042] S5. The completely dried and cured solid electrolyte membrane is taken out from the drying box 51 and peeled off from the base film by the peeling roller 61. The peeled solid electrolyte membrane is wound up by the electrolyte membrane winding roller 62, while the peeled base film is recycled by the base film winding roller 63, finally obtaining an LLZTO solid electrolyte self-supporting membrane with a thickness of 70±0.5μm, a smooth and flat surface, and no cracks.

[0043] like Figure 4 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 147.26 mAh g. -1 After 100 cycles, the discharge specific capacity is 119.44 mAh g. -1 The capacity retention rate was 81.11%.

[0044] Example 3 The difference from Example 2 is that in step S2, the coating speed is set to 10 mm / s. The slurry delivery rate is controlled at 1.5 mm / s by a screw pump. Everything else is the same as in Example 2.

[0045] The final obtained LLZTO solid electrolyte self-supporting membrane has a thickness of approximately 80±0.5μm, a smooth and flat surface, and is free of cracks.

[0046] like Figure 5 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 150 mAh g. -1 After 100 cycles, the discharge specific capacity is 139.05 mAh g. -1 The capacity retention rate was 92.7%.

[0047] Example 4 The difference from Example 2 is that in step S2, the coating speed is set to 15 mm / s. The slurry delivery rate is controlled at 2 mm / s by a screw pump. Everything else is the same as in Example 2.

[0048] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 70±0.5μm, a smooth and flat surface, and no cracks.

[0049] like Figure 6 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 149.93 mAh g. -1 After 100 cycles, the discharge specific capacity is 137.19 mAh g. -1 The capacity retention rate was 91.5%.

[0050] Example 5 The difference from Example 2 is that in step S2, the coating speed is set to 5 mm / s. The slurry delivery rate is controlled at 1.5 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 90°C, respectively, and the rest are the same as in Example 2.

[0051] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 80±0.5μm, a smooth and flat surface, and no cracks.

[0052] like Figure 7 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 150 mAh g. -1 After 100 cycles, the discharge specific capacity is 141.75 mAh g. -1 The capacity retention rate was 94.5%.

[0053] Example 6 The difference from Example 2 is that in step S2, the coating speed is set to 10 mm / s. The slurry delivery rate is controlled at 2 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 90°C, respectively, and the rest are the same as in Example 2.

[0054] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 90±0.5μm, a smooth and flat surface, and no cracks.

[0055] like Figure 8 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 147.23 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is 132.32 mAh g. -1 The capacity retention rate was 89.9%.

[0056] Example 7 The difference from Example 2 is that in step S2, the coating speed is set to 15 mm / s. The slurry delivery rate is controlled to 1 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 90°C, respectively, and the rest are the same as in Example 2.

[0057] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 60±0.5μm, a smooth and flat surface, and no cracks.

[0058] like Figure 9 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 148.16 mAh g. -1 After 100 cycles, the discharge specific capacity is 137.99 mAh g. -1 The capacity retention rate was 93.2%.

[0059] Example 8 The difference from Example 2 is that in step S2, the coating speed is set to 5 mm / s. The slurry delivery rate is controlled at 2 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 100°C, respectively, and the rest are the same as in Example 2.

[0060] The final result is an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 100±0.5μm, a smooth and flat surface, and no cracks.

[0061] like Figure 10 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 148.34 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is 130.05 mAh g. -1 The capacity retention rate was 87.7%.

[0062] Example 9 The difference from Example 2 is that in step S2, the coating speed is set to 10 mm / s. The slurry delivery rate is controlled to 1 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 100°C, respectively, and the rest are the same as in Example 2.

[0063] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 60±0.5μm, a smooth and flat surface, and no cracks.

[0064] like Figure 11 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 144.26 mAh g. -1 After 100 cycles, the discharge specific capacity is 133.22 mAh g. -1 The capacity retention rate was 92.4%.

[0065] Example 10 The difference from Example 2 is that in step S2, the coating speed is set to 15 mm / s. The slurry delivery rate is controlled at 1.5 mm / s by a screw pump. The temperatures of the three zones of the drying oven are set to 50°C, 70°C, and 100°C, respectively, and the rest are the same as in Example 2.

[0066] The final result was an LLZTO solid electrolyte self-supporting membrane with a thickness of approximately 70±0.5μm, a smooth and flat surface, and no cracks.

[0067] like Figure 12 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 147.4 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is 134.99 mAh g. -1 The capacity retention rate was 91.6%.

[0068] Comparative Example Solid electrolyte membranes were prepared using conventional blade coating. A 200 μm blade was used to coat the solid electrolyte membrane onto a tetrafluoroethylene (PTFE) plate. After coating, the membrane was cured using a UV curing machine at 30°C and 365 nm, followed by drying in an 80°C oven for 40 min.

[0069] The final thickness of the electrolyte membrane obtained in the comparative example was 83±8μm. Compared with the solid electrolyte membrane obtained by coating in this invention, the thickness of the solid electrolyte membrane obtained by blade coating is uneven, and the thickness varies greatly at any point on the membrane.

[0070] like Figure 13 As shown, at a current density of 0.1C, the first-cycle discharge specific capacity is 128.47 mAh g. -1 After 100 cycles, the discharge specific capacity is 70.74 mAh g. -1 The capacity retention rate is 55.06%, which is inferior to the electrolyte membrane obtained in Embodiments 2-10 of this utility model.

[0071] Therefore, this utility model adopts the above-mentioned extrusion plate coating equipment for preparing solid electrolyte membranes. It achieves quantitative extrusion of slurry through a precision slit die, and combines multi-stage gradient drying process and online real-time thickness measurement closed-loop control to successfully solve the key technical problems of uneven thickness, easy generation of defects, difficulty in ultra-thinning and low production efficiency in the preparation of solid electrolyte membranes by traditional casting, hot pressing and other methods.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. An extrusion plate coating apparatus for preparing solid electrolyte membranes, characterized in that: The equipment includes a main body, which is equipped with a slurry supply unit, an extrusion coating unit, a thickness measurement control system, a multi-stage drying unit, and a peeling and winding unit. The slurry supply unit is located on one side of the extrusion coating unit, and the screw pump of the slurry supply unit is connected to the coating die of the extrusion coating unit. The multi-stage drying unit is located on the discharge side of the extrusion coating unit. The thickness measurement probe of the thickness measurement control system is located inside the multi-stage drying unit. The peeling and winding unit is located on the discharge side of the multi-stage drying unit.

2. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 1, characterized in that: The slurry supply unit includes a slurry storage tank and a screw pump. The screw pump is located at the bottom of the slurry storage tank. The inlet of the screw pump is connected to the outlet of the slurry storage tank. The outlet of the screw pump is connected to the inner cavity of the coating die head through a slurry delivery pipe.

3. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 2, characterized in that: The extrusion coating unit includes a coating die, a fixed base, a support base, and a moving component. Two fixed bases are symmetrically arranged and are fixedly connected to the main body of the equipment. The support base is connected to the upper side of the two fixed bases through the moving component, and the coating die is fixedly connected to the upper side of the support base. The moving component includes a fixed block, a sliding block, a slide rail, and a telescopic cylinder. The fixed block is fixedly connected to the upper side of the fixed base, the sliding block is fixedly connected to the lower side of the support base, the sliding block and the fixed block are connected by the slide rail, and the telescopic cylinder is disposed between the fixed bases. One end of the telescopic cylinder is fixedly connected to the main body of the equipment, and the other end of the telescopic cylinder is fixedly connected to the support base.

4. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 3, characterized in that: The coating die head includes an upper die head and a lower die head, with a coating slit between them. The upper and lower dies head form a die head lip on the discharge side of the coating slit. The rear sides of the upper and lower dies head are connected by a hinge, with a handle on the upper side of the hinge. The lower die head has a storage chamber in the middle, and a connecting pipe connected to a slurry delivery pipe is located on the rear side of the lower die head. Both the connecting pipe and the coating slit are connected to the storage chamber. The upper die head is equipped with an adjustment component for adjusting the gap of the coating slit.

5. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 4, characterized in that: The thickness measurement control system includes a control box and an online thickness measurement mechanism. The control box is equipped with a central processing unit with data processing and closed-loop control algorithms. The online thickness measurement mechanism, slurry supply unit, extrusion coating unit, multi-stage drying unit, and peeling and winding unit are all electrically connected to the control box. The online thickness measurement mechanism includes several thickness measurement probes, which are beta-ray thickness gauges or infrared thickness gauges.

6. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 5, characterized in that: The multi-stage drying unit includes a segmented drying chamber with several parallel conveyor rollers inside. A thickness measuring probe is installed on the side wall of the drying chamber and is flush with the height of the conveyor rollers.

7. The extrusion plate coating equipment for preparing solid electrolyte membranes according to claim 6, characterized in that: The peeling and winding unit includes a peeling roller, an electrolyte membrane winding roller, and a base film winding roller. The peeling roller is located on one side of the discharge port of the multi-stage drying unit, while the electrolyte membrane winding roller and the base film winding roller are located below the multi-stage drying unit and inside the main body of the equipment.

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