Preparation method of full-dry-method solid-state battery and battery

Abstract

The invention discloses a preparation method of a full-dry-method solid-state battery and the battery. The preparation method comprises the following steps: S1, preparing a negative pole piece in a dry method; s2, covering the negative pole piece prepared in the step S1 with a lithium supplementing film in a rolling manner; s3, attaching solid electrolyte membranes on two sides of the negative pole piece covered with the lithium supplementing membrane prepared in the step S2 by using a calendering roller; s4, compounding the negative pole piece coated with the solid electrolyte membrane and the positive pole piece prepared in the step S3 into a battery cell through rolling; and S5, assembling the cut tabs prepared in the step S4 to prepare the solid-state battery. The battery cell preparation method disclosed by the invention has obvious advantages in the aspects of reducing the production cost of the battery, reducing the energy consumption, improving the environmental protection property, enhancing the battery performance, improving the mechanical strength, saving the labor force, developing a novel electrode structure and the like.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a method for preparing a fully dry solid-state battery cell and a battery. Background Art

[0002] Although lithium-ion batteries (LIBs) are widely regarded as environmentally friendly energy storage solutions, their potential in promoting sustainable development has not yet been fully realized. Conventional wet electrode processing technology is a key step in the production of lithium-ion (LIBs) and is known for its ability to ensure uniformity, scalability and high quality of electrodes. This process involves uniformly coating a slurry containing active materials and conductive additives on a current collector, which is critical for the consistency of battery electrochemical performance; however, the early stages of wet electrode manufacturing are contaminated by toxic and volatile solvents (such as N-methylpyrrolidone NMP), especially during the drying process. The use of solvents may lead to solvent emissions and waste generation, posing a threat to the environment and may cause potential safety risks. In recent years, more and more research evidence has revealed the potential impact of these solvents on the environment; in the face of this challenge, many researchers and manufacturers in the battery field are working to reduce or even eliminate the use of solvents in the electrode manufacturing process. In order to reduce energy consumption in the battery manufacturing process, researchers are looking for alternatives to solvents such as NMP to significantly reduce energy use and other processing technologies including reducing solvent use, recycling alternative solvents, adopting aqueous processing methods, and developing processing technologies that do not require the use of solvents at all. These environmental and safety issues associated with solvents have prompted research and development toward dry processing methods that reduce or eliminate solvent use. Summary of the invention

[0003] In order to reduce environmental pollution caused by solvents in the battery preparation process, the present invention provides a method for preparing a fully dry solid-state battery cell, comprising: a method for preparing a fully dry solid-state battery, comprising the following steps: S1: preparing a negative electrode plate in a dry manner; S2: covering the negative electrode plate prepared in step S1 with a lithium replenishing film by rolling; S3: attaching a solid electrolyte film to both sides of the negative electrode plate covered with the lithium replenishing film prepared in step S2 by a calendering roller; S4: combining the negative electrode plate coated with the solid electrolyte film prepared in step S3 with the positive electrode plate by rolling to form a battery cell; S5: cutting the tabs prepared in step S4 and assembling them to form a solid-state battery.

[0004] Furthermore, the positive electrode sheet in step S4 is prepared by a dry method.

[0005] Furthermore, in step S3, two calendering rollers are provided, which are respectively provided on both sides of the negative electrode sheet. The lithium replenishing film is respectively unwound into the gap between the two calendering rollers by two unwinding devices to attach the lithium replenishing film to both sides of the negative electrode sheet.

[0006] Furthermore, the dry method of preparing the negative electrode sheet in step S1 includes directly adding the fibrous negative electrode active material into the roller gap between the first film-forming roller and the second film-forming roller, and setting the roller speed of the second film-forming roller to be greater than the roller speed of the first film-forming roller to stretch the negative electrode active material into a film.

[0007] Furthermore, the preparation method of the positive electrode sheet of step S3 includes adding fibrous positive electrode active material into the gap between two first positive electrode film-forming rollers and a second negative electrode film-forming roller, and the roller speed of the second negative electrode film-forming roller is greater than the roller speed of the first positive electrode film-forming roller to stretch the positive electrode material active material into a film.

[0008] Furthermore, in step S3, solid electrolyte membranes are attached to both sides of the negative electrode plate at the same time.

[0009] Furthermore, a thinning roller is provided in the process of preparing the positive electrode sheet, and the thickness of the positive electrode sheet can be adjusted by the thinning roller.

[0010] The battery cell preparation method of the present invention can reduce production costs, reduce energy consumption, improve environmental protection, enhance battery performance, improve mechanical strength, save labor, and develop new electrode structures, showing obvious advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the preparation method of the all-dry solid-state battery of the present invention. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] like Figure 1 As shown, the preparation method of the fully dry solid-state battery of the present invention mainly includes the following steps: first, a negative electrode plate coated with a negative electrode active material is prepared by a dry method in the dry negative electrode module 1; then, lithium tapes are attached to both sides of the prepared negative electrode plate in the lithium tape transfer composite module 30; then, a solid electrolyte layer is coated on both sides of the negative electrode plate to which the lithium tape is attached in the solid electrolyte transfer coating module 47; finally, it is compounded with the positive electrode plate prepared in the dry positive electrode module 1, and finally a complete battery is formed through processes such as cutting the pole ears and sticking the film.

[0014] In this embodiment, the dry negative electrode module 1 is used to prepare negative electrode sheets. The dry negative electrode module 1 includes a first negative electrode active material carrier 2 and a second negative electrode active material carrier 8, a negative electrode foil unwinding device 9 and a plurality of rollers (described in detail below). The first negative electrode active material carrier 2 and the second negative electrode active material carrier 8 are funnel-shaped, showing a large top and a small bottom, and negative electrode active materials are respectively contained inside. In this embodiment, the negative electrode active material in the carrier is in a fiber powder state, which is different from the liquid state of the negative electrode active material in the preparation of the negative electrode sheet by the wet process. In this embodiment, the active material in the negative electrode active material carrier is in a powder state, and there is no need to use a solvent to dissolve the negative electrode active material. The negative electrode active material can directly enter the subsequent roller gap from the carrier, and the thickness of the negative electrode sheet and various performances can be controlled by adjusting the roller gap spacing and the speed of each roller. Specifically, the multiple rollers in the negative electrode module include a first film-forming roller 3, a second film-forming roller 4, a third film-forming roller 6 and a fourth film-forming roller 7, as well as a first composite roller 5 and a second composite roller 8. A first roller gap is formed between the first film-forming roller 3 and the second film-forming roller 4; a second roller gap is formed between the second film-forming roller 4 and the first composite roller 5; a third roller gap is formed between the first mixing roller 5 and the second mixing roller 8; a fourth roller gap is formed between the second mixing roller 8 and the fourth film-forming roller 7; and a fifth roller gap is formed between the fourth film-forming roller 7 and the third film-forming roller 6. In this embodiment, the gaps of the various roller gaps can be set to different gaps or the same gaps, and the gaps of the various roller gaps can be specifically set and freely selected according to the thickness of the negative electrode sheet to be prepared.

[0015] When preparing the negative electrode plate of the present invention, all rollers are first preheated to the set temperature, and then the rotation of each roller is started, and at the same time, each fibrous negative electrode material in the first negative electrode material carrier 2 and the second negative electrode material carrier 58 is successively entered into the first roller gap and the fifth roller gap along with each roller. In this embodiment, the rotation speeds of the first film-forming roller 3 and the second film-forming roller 4 are different. Since the speed of the second film-forming roller 4 is greater than the speed of the first film-forming roller 3, there is a large speed difference between the two. In this embodiment, the speed between the first film-forming roller 3 and the second film-forming roller 4 is set to be in the range of 0-3m / min. The negative electrode material in the first roller gap is sheared and stretched by the speed difference to form a film, and enters the second roller gap closely against the second film-forming roller 4, and then enters the third roller gap along with the first composite roller 5; similarly, the negative electrode material in the fifth roller gap is caused by the third film-forming roller 6 and the fourth film-forming roller 6. The speed difference between the film rollers 7 is also sheared and stretched into a film and follows the progress of the fourth film roller 7 to the fourth roller gap, and then follows the second composite roller 8 to enter the third roller gap; at this time, the negative electrode collector copper foil wound by the negative electrode foil unwinding device 9 also enters the third roller gap, and the first negative electrode film formed by the first roller gap and the second roller gap is attached to the left side of the negative electrode collector copper foil; at the same time, the second negative electrode film formed by the fifth roller gap and the fourth roller gap is attached to the right side of the negative electrode collector copper foil; thus, negative electrode materials are attached to both sides of the negative electrode collector copper foil, forming a negative electrode sheet with negative electrode materials attached to both sides. In order to accurately control the surface density and compaction density of the negative electrode sheet in this embodiment, the roller speeds of the first film roller 3, the second film roller 4 and the first composite roller 5, and the roller speeds of the second film roller 6 and the second composite roller 8 can be adjusted.

[0016] The outer layer of the prepared double-sided negative electrode sheet is attached with a lithium supplement layer through a lithium supplement module 30. The lithium supplement module 30 for supplementing the negative electrode sheet with lithium in the present invention includes a first lithium strip unwinding device 22 and a first lithium strip receiving base film winding device 23; a second lithium strip unwinding device 28 and a second lithium strip receiving base film winding device 29, a first calendering roller 24, a first calendering back roller 25; a second calendering roller 27 and a second calendering back roller 26. The lithium ribbon carried by the first lithium ribbon unwinding device 22 enters the roller gap between the first calendering roller 24 and the first calendering back roller 25 after unwinding and is rolled and compounded to the left side of the negative electrode sheet, and the remaining lithium ribbon is rolled up by the first lithium ribbon receiving base film winding device 23; at the same time, the lithium ribbon carried by the second lithium ribbon unwinding device 28 enters the roller gap between the second calendering roller 27 and the second calendering back roller 26 after unwinding and is rolled and compounded to the right side of the negative electrode sheet, and the remaining lithium ribbon is rolled up by the second lithium ribbon receiving base film winding device 29. In this embodiment, a lithium layer is attached to both sides of the negative electrode sheet through a lithium replenishing module, so as to make up for the problem of low initial efficiency caused by the reaction of the PTFE binder applicable to the dry electrode with lithium ions during the first charging process of the battery. The lithium replenishing module of this embodiment can make up for the lithium ions consumed by PTFE, and the lithium is replenished by calendering, the process is simple, and it can be formed continuously with the process of preparing the negative electrode sheet, and the efficiency is high. In this embodiment, the thickness of the lithium strip can be adjusted as needed by only adjusting the gap between the first calendering roller 24 and the first calendering back roller 25 and the roller speed of the calendering roller, which is convenient and quick.

[0017] After the negative electrode plate is supplemented with lithium, a solid electrolyte layer is attached, which can be achieved in this embodiment through a solid electrolyte transfer coating module 47. The solid electrolyte transfer coating module 47 includes a solid electrolyte membrane first unwinding device 31 and a solid electrolyte membrane receiving base membrane first winding device 32; a solid electrolyte membrane second unwinding device 35 and a solid electrolyte membrane receiving base membrane second winding device 36, a third calendering roller 33 and a third calendering back roller 34. After being unwound from the first unwinding device 31 of the solid electrolyte membrane and the second unwinding device 35 of the solid electrolyte membrane, the solid electrolyte membrane enters into the roller gap between the third calendering roller 33 and the third calendering back roller 34. At the same time, the negative electrode sheet composited with the lithium supplement tape enters into the roller gap. After calendering, the solid electrolyte membrane is transferred to both sides of the composite negative electrode sheet, so that both sides of the negative electrode sheet are coated with solid electrolyte. The thickness of the solid electrolyte on the electrode sheet is adjusted by adjusting the gap between the third calendering roller 33 and the third calendering back roller 34, so as to efficiently realize the attachment of the solid electrolyte. Then the remaining solid electrolyte is wound up by the first winding device 32 of the solid electrolyte membrane receiving base film and the second winding device 36 of the solid electrolyte membrane receiving base film. In this embodiment, in order to make the solid electrolyte membrane tightly and firmly attached to the negative electrode plate, we set the unwinding speed of the first unwinding device 31 of the solid electrolyte membrane to 1-100m / min, and the transfer pressure between the third calendering roller 33 and the third calendering back roller 34 to 1-50psi, and the roller gap between the third calendering roller 33 and the third calendering back roller 34 can be set within the range of 0-2mm.

[0018] In this embodiment, the positive electrode sheet of the battery is also prepared by a dry method, mainly through a dry positive electrode module 21. The dry positive electrode module 21 of this embodiment includes a first positive electrode material carrying device 10 and a second positive electrode material carrying device 19, a positive electrode foil unwinding device 20 and a plurality of rollers (described in detail below). The first positive electrode material carrying device 10 and the second positive electrode material carrying device 19 are constructed in a funnel shape, presenting a shape of being large at the top and small at the bottom. The positive electrode carrying devices 10 and 19 are respectively filled with positive electrode active materials for preparing batteries, and the positive electrode active materials in the positive electrode carrying devices are in the form of fiber powder. The multiple rollers in the dry positive electrode module 21 include a first positive electrode film-forming roller 11, a second positive electrode film-forming roller 12, a third positive electrode film-forming roller 15 and a fourth positive electrode film-forming roller 16, a first thinning roller 12, a second thinning roller 13, a third thinning roller 14, a fourth thinning roller 16, a fifth thinning roller 17, and a sixth thinning roller 18. A third composite roller 15 and a fourth composite roller 18. At the same time, the fiberized positive electrode active powder is added to the positive electrode carrying devices 10 and 19 in the hopper. After the temperature of all the hot rollers reaches the set temperature, the rollers are turned on, and the fiberized material enters the roller gap with the rotation of the rollers. Due to the large speed difference in the first-stage roller gap, the positive electrode material becomes a self-supporting film after shearing and stretching due to the speed difference. Due to the existence of the speed difference, the electrode film is formed in the first-stage roller gap and then enters the second-stage roller gap closely against the second roller. The speed difference in the second-stage roller gap further thins the electrode film. By adjusting the speed difference of the roller gap, the surface density of the electrode film can be accurately controlled. When the electrode film enters the third-stage roller gap, the speed difference of the third-stage roller gap is small, mainly to increase the compaction density of the electrode film.

[0019] The positive electrode sheet and the negative electrode sheet coated with a solid electrolyte enter the roller gap between the first composite roller 38 and the second composite roller 39 to be composited into a battery cell membrane, and then the battery cell membrane is cut into positive electrode tabs by a laser tab cutting device, and then the negative electrode tabs are cut out by a negative electrode laser and tab device 42, and then the battery cell is wound into a battery cell by a winding device 43, and a termination tape is affixed to the outside of the battery cell by a gluing device 44, and finally the battery cell is conveyed to a conveyor belt 46 by a robot 45, and the fully dry solid-state battery cell process is completed.

[0020] The multi-roller finishing rolling, double-sided compounding, transfer printing lithium replenishment and transfer printing solid electrolyte coating process routes designed in the present invention realize film formation, thinning and compaction of positive and negative electrode active materials by multi-roller continuous rolling, and then compound with the current collector, transfer printing lithium replenishment by lithium belt calendering, and enter solid electrolyte calendering transfer coating, and form a composite battery cell film after compounding with the positive electrode hot roller calendering, and then wind it into a battery cell offline after laser cutting of the pole ears. This method realizes efficient preparation from powder to battery cells with simple process steps. This method can also realize full dry preparation of multi-form battery cells by adjusting the winding method or introducing a lamination process.

[0021] The battery preparation method of the present invention is a new solvent-free solid-state battery production process. The dry-process positive and negative electrode plates are prepared by double-sided film formation, thinning and composite process design. The present invention coats the solid electrolyte onto the lithium-supplemented negative electrode plate through a solid electrolyte transfer process, and then composites it with the dry-process electrode positive electrode through hot roller calendering. The full pole ear structure is laser cut and then wound, thereby realizing the preparation of solvent-free high-performance all-dry solid-state cylindrical battery cells.

[0022] The battery preparation method of the present invention has significant advantages. First, the battery preparation method of the present invention reduces the production processes such as solvent use, recovery, evaporation and drying, and the applicability of corresponding raw materials during the production process, thereby significantly reducing the production cost of the battery. Compared with the existing battery preparation method, the production cost can be reduced by about 10% to 15%. Secondly, compared with the traditional wet process for preparing batteries, the dry process for preparing batteries in the present invention avoids the solvent recovery and drying process, thereby greatly reducing energy consumption and labor time, and improving production efficiency. In addition, the dry process for preparing batteries in the present invention also shows great potential in environmental protection, which helps to reduce carbon dioxide emissions during the production process.

[0023] The dry process for preparing battery cells of the present invention can also increase the compaction density of the electrode, reduce the porosity, and improve the ion conductivity; it can also increase the mechanical strength of the battery, and even if a very small amount of PVDF is used as a binder, an electrode with high mechanical strength can be manufactured.

[0024] In summary, the battery cell preparation method of the present invention can reduce production costs, reduce energy consumption, improve environmental protection, enhance battery performance, improve mechanical strength, save labor, and develop new electrode structures, showing obvious advantages.

[0025] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a fully dry solid-state battery, characterized in that: The steps include: S1: dry method to prepare negative electrode sheet; S2: Covering the negative electrode sheet prepared in step S1 with a lithium supplement film by rolling; S3: attaching a solid electrolyte membrane to both sides of the negative electrode sheet covered with the lithium supplement film prepared in step S2 by using a calendering roller; S4: The negative electrode sheet coated with the solid electrolyte membrane and the positive electrode sheet prepared in step S3 are combined into a battery cell by rolling; S5: Cut the tabs produced in step S4 and assemble them to form a solid-state battery.

2. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: The positive electrode sheet in step S4 is prepared by a dry method.

3. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: In step S3, two calendering rollers are provided, which are respectively provided on both sides of the negative electrode sheet. The lithium replenishing film is respectively unwound into the gap between the two calendering rollers by two unwinding devices to attach the lithium replenishing film to both sides of the negative electrode sheet.

4. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: In step S1, the dry method for preparing the negative electrode sheet includes directly adding the fibrous negative electrode active material into the roller gap between the first film-forming roller and the second film-forming roller, and setting the roller speed of the second film-forming roller to be greater than the roller speed of the first film-forming roller to stretch the negative electrode active material into a film.

5. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: The method for preparing the positive electrode sheet of step S3 includes adding fibrous positive electrode active material into the gap between two first positive electrode film-forming rollers and a second negative electrode film-forming roller, wherein the roller speed of the second negative electrode film-forming roller is greater than the roller speed of the first positive electrode film-forming roller to stretch the positive electrode material active material into a film.

6. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: In step S3, solid electrolyte membranes are attached to both sides of the negative electrode plate at the same time.

7. The method for preparing a fully dry solid-state battery according to claim 1, characterized in that: A thinning roller is also provided during the preparation process of the positive electrode sheet, and the thickness of the positive electrode sheet can be adjusted by the thinning roller.

8. A solid-state battery, characterized in that: The solid-state battery is prepared by the method for preparing a fully dry solid-state battery cell as described in any one of claims 1 to 7.

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