Preparation method of positive plate with supporting frame and all-solid-state battery

Abstract

The invention provides a preparation method of a positive plate with a supporting frame and an all-solid-state battery, and relates to the technical field of battery manufacturing. The preparation method comprises the following steps: preparing supporting frame slurry, increasing an empty foil space around a positive electrode material area in a positive electrode intermittent coating manner, and arranging the supporting frame slurry on two sides of a longitudinal material area in a side coating manner; after unwinding, carrying out transverse dispensing and drying, transversely arranging the supporting frame slurry on the two transverse sides of the positive plate material area at the pause gap of the die-cutting pole plate, and drying the supporting frame slurry; and carrying out die cutting to obtain the positive plate with the support frame. Edge collapse and breakage caused by pressure of an isostatic pressing process can be effectively improved, and the short-circuit rate of the battery cell is reduced.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and in particular to a method for preparing a positive electrode sheet with a support frame and an all-solid-state battery. Background Technology

[0002] Solid-state batteries, with their significant advantages in high energy density and excellent safety performance, have become an important direction for promoting the advancement of power battery technology in new energy vehicles. In the structure of a solid-state battery, the electrode sheet, as the core component of the cell, directly affects the overall performance of the cell and the yield control during the production process due to the assembly precision and supporting stability of the electrode sheet and the electrolyte membrane. Currently, the industry mainly adopts three technical approaches to address the electrode support and positioning issues: First, blank aluminum or copper foil is reserved at the electrode edge as a support structure. This method relies on the mechanical rigidity of the foil itself to fix the electrolyte membrane. However, due to the generally insufficient interfacial bonding between the blank foil and the electrolyte membrane, interfacial peeling is prone to occur during subsequent cold pressing processes, leading to cell structure failure. Second, an independent sealing frame is used. After electrode preparation, a resin or ceramic sealing frame is adhered to the electrode edge using an adhesive. While this method enhances the support effect to some extent, it introduces a complex bonding process, and the dimensional matching accuracy between the sealing frame and the electrode is difficult to control precisely, often causing assembly difficulties due to minor deviations. Third, an insulating slurry is coated on one side of the electrode as a positioning reference. However, this solution lacks a closed frame design and cannot provide uniform circumferential support, making the electrolyte membrane prone to cracking in uncoated areas. The aforementioned existing technical solutions all have obvious limitations and cannot simultaneously solve key problems such as insufficient assembly alignment accuracy, inadequate support strength, and cumbersome process flow, which seriously hinder the large-scale production and commercial application of all-solid-state batteries.

[0003] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing a positive electrode with a support frame and an all-solid-state battery to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application provides a method for preparing a positive electrode sheet with a support frame, comprising: A support frame slurry is prepared, and an empty foil space is added around the positive electrode material area by intermittent coating of the positive electrode. The support frame slurry is then placed on both sides of the longitudinal material area by edge coating. After unwinding, lateral glue application and drying are performed. During the interval when the die-cutting electrode is paused, the support frame slurry is laterally applied to both sides of the positive electrode material area and dried. After die-cutting, the positive electrode with the support frame is obtained.

[0006] Optionally, the method for preparing the support frame slurry includes: fully mixing and stirring the main material with the binder and solvent using a high-speed dispersion and stirring device to form a slurry.

[0007] Optionally, the main material includes at least one of boehmite, alumina, polyvinylidene fluoride, aramid, sulfide electrolyte, oxide electrolyte, and halide electrolyte.

[0008] Optionally, the adhesive includes at least one of polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyimide, polyisobutylene, and nitrile rubber.

[0009] Optionally, the solvent includes at least one selected from methanol, ethanol, isopropanol, dichloromethane, ethane, isooctane, dodecane, diethyl ether, carbon tetrachloride, and toluene.

[0010] Optionally, the positive electrode intermittent coating includes using an extrusion die pad to open a glue groove to achieve edge coating at the two sides of the material area, and the electrode sheet is edge coated on both sides, either on one or both sides.

[0011] Optionally, the width of the edge coating is 3-6 mm.

[0012] Optionally, the thickness of the edge coating is 40%-70% of the dry film thickness of the material area.

[0013] Optionally, the thickness of the edge coating is preferably 55% of the dry film thickness of the material area.

[0014] This application also provides an all-solid-state battery, including a positive electrode sheet with a support frame made by the method described above.

[0015] Compared with the prior art, the beneficial effects of this application include: This application provides a method for preparing a positive electrode sheet with a support frame. By constructing a closed support frame structure, the assembly accuracy and support stability of the electrode sheet and electrolyte membrane are effectively improved, while the manufacturing process is optimized. Compared to blank foil support methods, the closed support frame formed by coating and dispensing processes in this application provides a more stable support effect. Compared to adding an independent sealing frame, this application integrates the support frame preparation into the electrode sheet manufacturing process, simplifying the process steps. Unlike single-sided edge coating positioning methods, this application combines longitudinal edge coating and transverse dispensing to form a fully circumferential closed support structure, solving the problems of low alignment accuracy, insufficient support, and complex processes in traditional methods. Compared with existing technologies in the field of battery cells, the manufacturing method described in this invention is simpler in terms of process route, reducing the process complexity of traditional solid-state battery cell support frames; moreover, this manufacturing method is combined with coating and die-cutting processes, eliminating the low-capacity independent frame manufacturing process, thereby improving production efficiency and capacity; the increase in the size of the positive electrode edge coating insulation frame improves the stacking alignment and effectively mitigates edge collapse and breakage caused by isostatic pressing pressure, thereby reducing the battery cell short-circuit rate. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0017] Figure 1 This is a schematic diagram showing the edge coating position at the longitudinal material zone edge in the preparation method provided in the embodiment; Figure 2 This is a schematic diagram of the edge coating position at the edge of the transverse material area in the preparation method provided in the embodiment. Detailed Implementation

[0018] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0019] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0020] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0021] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0022] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0023] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0024] To better explain the technical solution provided in this application, the technical solution will be described in its entirety before proceeding with specific implementation methods.

[0025] In a first aspect, this application provides a method for preparing a positive electrode sheet with a support frame, comprising: A support frame slurry is prepared, and an empty foil space is added around the positive electrode material area by intermittent coating of the positive electrode. The support frame slurry is then placed on both sides of the longitudinal material area by edge coating. After unwinding, lateral glue application and drying are performed. During the interval when the die-cutting electrode is paused, the support frame slurry is laterally applied to both sides of the positive electrode material area and dried. After die-cutting, the positive electrode with the support frame is obtained.

[0026] In practical applications, the support frame slurry can be understood as the basic material used to form the support frame structure. It can be achieved by mixing inorganic fillers with dispersants and plasticizers to form a slurry, for example, by mixing inorganic materials such as silica and magnesium oxide with dispersion systems such as polyvinyl alcohol and sodium carboxymethyl cellulose. Intermittent coating of the positive electrode refers to intermittent coating achieved by controlling the start and stop of the coating equipment during the coating process. Specifically, this can be achieved by adjusting the moving speed and coating frequency of the coating head, for example, by using a reciprocating coating machine or an intermittent extrusion coating device. Side coating of the support frame slurry on both sides of the longitudinal material zone can be achieved by adding independent slurry delivery pipes and coating heads to the coating equipment, for example, by using a dual-channel coating head or a split coating system. The lateral dispensing platform can be understood as a device used for precise dispensing of adhesive in the lateral direction of the electrode sheet. It can be achieved by setting positioning sensors and an automatic control system on the dispensing machine, for example, by using a vision-positioning dispensing system or a laser-guided dispensing device. An infrared drying oven is a device that uses the principle of infrared radiation to quickly dry coated materials. It can be achieved by setting infrared lamps of different power and a temperature control system, such as using a zoned temperature-controlled infrared oven or an adjustable power infrared drying device.

[0027] In an optional embodiment, the method for preparing the support frame slurry includes: thoroughly mixing and stirring the main material with the binder and solvent into a slurry using a high-speed dispersion and stirring device; The raw materials of the support frame slurry, calculated as 100% of the total mass, include 50%-70% of the main material, 5%-10% of the binder, and 25%-45% of the solvent.

[0028] Optionally, based on the total mass of the support frame mortar raw materials as 100%, the amount of main material can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, or any value between 50% and 70%; the amount of adhesive can be 5%, 6%, 7%, 8%, 9%, 10%, or any value between 5% and 10%; the amount of solvent can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, or any value between 35% and 45%.

[0029] In one optional embodiment, the host material includes at least one of boehmite, alumina, polyvinylidene fluoride, aramid, sulfide electrolyte, oxide electrolyte, and halide electrolyte.

[0030] In one optional embodiment, the adhesive comprises at least one of polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyimide, polyisobutylene, and nitrile rubber.

[0031] In an optional embodiment, the solvent includes at least one selected from methanol, ethanol, isopropanol, dichloromethane, ethane, isooctane, dodecane, diethyl ether, carbon tetrachloride, and toluene.

[0032] In an optional embodiment, the positive electrode intermittent coating includes using an extrusion die pad to open a glue groove to achieve edge coating at the two edges of the material area, and the electrode sheet is edge coated on both sides, either on one or both sides.

[0033] In one optional embodiment, the width of the edge coating is 3-6 mm. Based on the dimensional deviations of the positive and negative electrode sheets and the edge dimensions of the die-cutting waste, a preferred edge coating width is 4.5 mm.

[0034] Optionally, the width of the edge coating can be 3 mm, 4 mm, 5 mm, 6 mm, or any value between 3 and 6 mm.

[0035] In one optional embodiment, the thickness of the edge coating is 40%-70% of the dry film thickness of the material area. Based on the variation range of the total thickness of the electrode sheet after rolling and isostatic pressing, the thickness of the edge coating is preferably 55% of the dry film thickness of the material area.

[0036] Optionally, the thickness of the edge coating can be 40%, 45%, 50%, 55%, 60%, 65%, 70% of the dry film thickness of the material area, or any value between 40% and 70%.

[0037] Understandably, the technical solution of this application improves the assembly accuracy and support stability of the electrode and electrolyte membrane by constructing a closed support frame structure, while optimizing the manufacturing process. First, a support frame slurry is prepared. This slurry serves as the base material for the support structure, and its composition is designed to ensure good adhesion to the electrode interface. Further, an intermittent coating method is used to increase the size of the empty foil around the positive electrode material area. The precise pause characteristics of intermittent coating reserve space, avoiding interference from the active material area to subsequent processes. Simultaneously, support frame slurry is applied to both sides of the longitudinal material area during the edge coating process. The edge coating process synchronously forms the longitudinal support edge during coating, thereby achieving high-precision alignment in the longitudinal direction.

[0038] After the die-cutting machine unwinds the coil, a transverse dispensing platform and an infrared drying oven are added. Dispensing is performed on both sides transversely while the die-cutting electrode is paused. Specifically, the dispensing process utilizes the stationary state of the electrode to ensure precise positioning of the dispensing position, while infrared drying rapidly solidifies the slurry, preventing its flow and deformation. Thus, the transverse support formed by dispensing, combined with the longitudinal edge coating, constitutes a closed frame, providing full circumferential support to prevent electrolyte membrane rupture. Finally, the preparation is completed through drying and die-cutting processes. This process integrates coating and dispensing, avoiding the multi-step operation of traditionally adding a separate sealing frame, significantly simplifying the process complexity.

[0039] The above technical solutions effectively solve the problems of low alignment accuracy, insufficient support stability, and complex processes in the assembly of all-solid-state battery electrodes and electrolyte membranes, and realize an efficient and stable electrode preparation process.

[0040] Secondly, this application also provides an all-solid-state battery, including a positive electrode sheet with a support frame made by the method described above.

[0041] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0042] Example 1 This embodiment provides a method for preparing a positive electrode sheet with a support frame, the specific steps of which are as follows: Preparation of the slurry for the support frame: Using a high-speed dispersion and stirring device, the main material boehmite (70wt%), the binder polyvinylidene fluoride (5wt%), and the solvent N-methylpyrrolidone (25wt%) are thoroughly mixed and stirred for 2 hours until the slurry is uniform and free of particles.

[0043] Positive electrode intermittent coating: The positive electrode sheet adopts an intermittent coating process. The extrusion die pad has a dispensing groove, and edge coating is applied to positions a and b on both sides of the material area. Figure 1 As shown. Edge coating is applied to both single and double sides, with a width of 4.5 mm and a thickness of 55% of the dry film thickness of the material area. After coating, it is dried with hot air (80℃, 5 minutes).

[0044] Side coating, drying, and die-cutting of the material area: After die-cutting and material placement, use two external dispensing heads to apply edge coatings (c and d) to the transverse edges of the material area, as follows: Figure 2As shown, the edge coating width is 4.5mm, and the thickness is the same as that of the intermittent coating edge coating. It is then rapidly dried in an infrared oven (temperature 120℃, time 30 seconds), and finally die-cut into sheets according to the size of the negative electrode sheet using a metal die cutter to form a complete support frame on all four sides.

[0045] After performing stacking tests, overhang tests and isostatic voltage tests on the cells are conducted to detect short circuits.

[0046] Example 2 This embodiment provides a method for preparing a positive electrode sheet with a support frame, the specific steps of which are as follows: Preparation of the slurry for the support frame: Using a high-speed dispersion and stirring device, the main material boehmite (70wt%), the binder polyvinylidene fluoride (5wt%), and the solvent N-methylpyrrolidone (25wt%) are thoroughly mixed and stirred for 2 hours until the slurry is uniform and free of particles.

[0047] The electrode sheet is coated using an intermittent coating process. A dot groove is created in the extrusion die pad to apply coating to the edges of the material area. Both sides are coated, with a coating width of 3mm and a thickness of 40% of the dry film thickness of the material area. After coating, the sheet is dried with hot air (70℃, 6 minutes).

[0048] Side coating, drying, and die-cutting of the material area: After die-cutting and feeding, two external dispensing heads are used to apply side coating to the horizontal edges of the material area. The side coating width is 3mm, and the thickness is 40% of the dry film thickness of the material area. Then, it is quickly dried in an infrared oven (temperature 100℃, time 40 seconds). Finally, it is die-cut into sheets according to the size of the negative electrode sheet using a metal die cutter to form a complete support frame on all four sides.

[0049] After performing stacking tests, overhang tests and isostatic voltage tests on the cells are conducted to detect short circuits.

[0050] Example 3 This embodiment provides a method for preparing a positive electrode sheet with a support frame, the specific steps of which are as follows: Preparation of the slurry for the support frame: Using a high-speed dispersion and stirring device, the main material boehmite (70wt%), the binder polyvinylidene fluoride (5wt%), and the solvent N-methylpyrrolidone (25wt%) are thoroughly mixed and stirred for 2 hours until the slurry is uniform and free of particles.

[0051] The electrode sheet is coated using an intermittent coating process. A dotted groove is created in the extrusion die pad to apply edge coating to both sides of the material area. Edge coating is applied to both single and double sides, with a width of 6mm and a thickness of 70% of the dry film thickness of the material area. After coating, it is dried with hot air (90℃, 4 minutes).

[0052] Side coating, drying, and die-cutting of the material area: After die-cutting and feeding, two external dispensing heads are used to apply side coating to the horizontal edges of the material area. The side coating width is 6mm, and the thickness is 70% of the dry film thickness of the material area. Then, it is quickly dried in an infrared oven (temperature 130℃, time 20 seconds). Finally, it is die-cut into sheets according to the size of the negative electrode sheet using a metal die cutter to form a complete support frame on four sides.

[0053] After performing stacking tests, overhang tests and isostatic voltage tests on the cells are conducted to detect short circuits.

[0054] Comparative Example 1 This comparative example provides a conventional method for preparing a positive electrode, the specific steps of which are as follows: Positive electrode coating: A continuous coating process is adopted, without side coating steps. The positive electrode active material is directly coated on the current collector and then rolled after drying.

[0055] Die-cutting: The negative electrode sheet is directly die-cut to the size of the negative electrode sheet. The positive electrode sheet has no support frame and no protective structure at the edge of the material area.

[0056] After performing stacking tests, overhang tests and isostatic voltage tests on the cells are conducted to detect short circuits.

[0057] Comparative Example 2 This embodiment provides a method for preparing a positive electrode sheet with only longitudinal edge coating, the specific steps of which are as follows: Preparation of the support frame grout: Same as the grout formula in Example 1.

[0058] Positive electrode coating: The longitudinal side coating of the material area (4.5mm width, 55% thickness) is achieved only through intermittent coating, without the transverse side coating step.

[0059] Die-cutting: Direct die-cutting, the positive electrode sheet has only a partial support structure in the longitudinal direction, and no support frame in the transverse direction.

[0060] After performing stacking tests, overhang tests and isostatic voltage tests on the cells are conducted to detect short circuits.

[0061] Comparative Example 3 This comparative example provides a method for fabricating a support frame unit first and then combining it with the negative electrode sheet. The specific steps are as follows: Support frame fabrication: The entire support frame is coated with quick-drying resin adhesive. After drying, excess parts are removed by laser cutting to form the frame.

[0062] Negative electrode assembly: The support frame is attached to the negative electrode sheet, and then die-cut and stacked.

[0063] The short-circuit rate of the battery cell is measured after isostatic pressing.

[0064] The disc test results for the examples and comparative examples are shown in Table 1: Table 1 Comparison of short-circuit rates between laminated overhang and individual cells

[0065] As shown in Table 1, the battery cells prepared using the method of this application have smaller overhang dimensions and higher alignment compared to battery cells without support frames, with independent support frames, and with unidirectional support frames in the industry. Furthermore, the battery cell short-circuit rate is reduced more significantly, which improves both the quality of the battery cells and the overall production yield.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0067] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a positive electrode sheet with a support frame, characterized in that, include: A support frame slurry is prepared, and an empty foil space is added around the positive electrode material area by intermittent coating of the positive electrode. The support frame slurry is then placed on both sides of the longitudinal material area by edge coating. After unwinding, lateral glue application and drying are performed. During the interval when the die-cutting electrode is paused, the support frame slurry is laterally applied to both sides of the positive electrode material area and dried. After die-cutting, the positive electrode with the support frame is obtained.

2. The method for preparing a positive electrode sheet with a support frame according to claim 1, characterized in that, The method for preparing the support frame slurry includes: thoroughly mixing and stirring the main material, binder, and solvent into a slurry using a high-speed dispersion and stirring device; The raw materials of the support frame slurry, calculated as 100% of the total mass, include 50%-70% of the main material, 5%-10% of the binder, and 25%-45% of the solvent.

3. The method for preparing a positive electrode sheet with a support frame according to claim 2, characterized in that, The main material includes at least one of boehmite, alumina, polyvinylidene fluoride, aramid, sulfide electrolyte, oxide electrolyte, and halide electrolyte.

4. The method for preparing a positive electrode sheet with a support frame according to claim 2, characterized in that, The adhesive includes at least one of polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyimide, polyisobutylene, and nitrile rubber.

5. The method for preparing a positive electrode sheet with a support frame according to claim 2, characterized in that, The solvent includes at least one of methanol, ethanol, isopropanol, dichloromethane, ethane, isooctane, dodecane, diethyl ether, carbon tetrachloride, and toluene.

6. The method for preparing a positive electrode sheet with a support frame according to claim 1, characterized in that, The positive electrode intermittent coating includes using the extrusion die pad to open the glue groove to achieve edge coating on both sides of the material area, and the electrode sheet is edge coated on both sides, either on one or both sides.

7. The method for preparing a positive electrode sheet with a support frame according to claim 6, characterized in that, The width of the edge coating is 3-6 mm.

8. The method for preparing a positive electrode sheet with a support frame according to claim 6, characterized in that, The thickness of the edge coating is 40%-70% of the dry film thickness of the material area.

9. The method for preparing a positive electrode sheet with a support frame according to claim 8, characterized in that, The thickness of the edge coating is preferably 55% of the dry film thickness of the material area.

10. An all-solid-state battery, characterized in that, This includes a positive electrode sheet with a support frame manufactured using the method described in any one of claims 1-9.

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