Lithium battery, dry cathode thereof and preparation method of dry cathode

Abstract

The application provides a lithium battery, a dry positive electrode thereof and a preparation method of the dry positive electrode. The preparation method comprises the following steps: coating conductive glue in the first preset area on both sides of an aluminum foil substrate, and performing drying and winding to obtain the aluminum foil substrate with a conductive glue layer as a first substrate; coating insulating glue in the second preset area on the first substrate, and performing drying and winding to obtain the aluminum foil substrate with the conductive glue layer and the insulating glue layer as a second substrate; mixing, homogenizing and fiberizing a positive electrode main material, a conductive agent and a binder, and then performing film forming by using a film forming device to obtain a positive electrode film; aligning the positive electrode film with the first preset area of the second substrate, and performing composite rolling on the aligned positive electrode film and the second substrate to obtain a dry positive electrode sheet. By using the gravure technology to coat the insulating layer on the aluminum foil substrate in advance, the production efficiency is significantly improved, and the production cost is effectively reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a lithium battery, its dry positive electrode, and a method for preparing the dry positive electrode. Background Technology

[0002] Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as positive / negative electrode materials and a non-aqueous electrolyte solution. Electrodes are a crucial structure in lithium-ion batteries, significantly impacting their performance; therefore, electrode research has always been a key focus in the field.

[0003] Lithium-ion battery electrodes can be processed using various methods, among which dry processing has received considerable attention in the battery industry in recent years. Dry electrode fabrication processes eliminate the need for solvent evaporation, thus preventing binder migration. This allows for the fabrication of electrodes with extremely large thicknesses and high mass loadings without compromising the mechanical or electrochemical properties of lithium-ion batteries, effectively overcoming the inherent limitations of traditional wet processes.

[0004] However, when preparing positive electrode sheets using the dry electrode method, the film is directly laminated to the edge of the aluminum foil, and the ceramic insulating layer cannot be applied to the edge of the film area simultaneously. Usually, in the dry process, after film formation, a layer of UV-cured insulating adhesive or hot melt adhesive is applied to the edge. This process requires a high degree of flatness of the material area edge during film formation, and the adhesive coating equipment is expensive. Furthermore, the application of UV adhesive or hot melt adhesive requires a certain amount of time to cure, resulting in low production speed and insufficient capacity. Summary of the Invention

[0005] This application addresses the shortcomings of existing methods by proposing a lithium battery, its dry positive electrode, and a method for preparing the dry positive electrode, in order to solve the problems of low production speed and insufficient production capacity in the prior art.

[0006] In a first aspect, embodiments of this application provide a method for preparing a dry positive electrode for a lithium battery, the method comprising: Conductive adhesive is coated in a first preset area on both sides of an aluminum foil substrate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer as a first substrate. An insulating adhesive is applied to a second preset area on the first substrate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as a second substrate. The thickness of the insulating adhesive layer is greater than the thickness of the conductive adhesive layer. The second preset area is adjacent to the first preset area and the second preset area is located outside the second preset area. The insulating adhesive has fluidity so that the edge of the insulating adhesive layer obtained after drying contacts the edge of the conductive adhesive layer or the insulating adhesive layer partially overlaps the conductive adhesive layer. After uniformly mixing and fiberizing the positive electrode material, conductive agent and binder, a film-forming device is used to form a film to obtain a positive electrode film. The positive electrode film is aligned with the first preset area of ​​the second substrate, and the aligned positive electrode film and the second substrate are subjected to composite rolling to obtain a dry positive electrode sheet.

[0007] Optionally, conductive adhesive is coated onto a first predetermined area on both sides of an aluminum foil substrate, and then dried and wound to obtain an aluminum foil substrate with a conductive adhesive layer as a first substrate, comprising: Using carbon-containing adhesive as the conductive adhesive, a first gravure plate is used to coat the conductive adhesive in a first preset area on both sides of the aluminum foil substrate. The first gravure plate is provided with a plurality of first grooves of the same size as the first preset area. The depth of the first groove is related to the required thickness of the conductive adhesive layer. The aluminum foil substrate coated with the conductive adhesive is dried to obtain an aluminum foil substrate having a conductive adhesive layer with a thickness of 1 micrometer to 5 micrometers, and then wound up to obtain an aluminum foil substrate having the conductive adhesive layer as the first substrate.

[0008] Optionally, an insulating adhesive is applied to a second predetermined area on the first substrate, and then dried and wound to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as a second substrate, comprising: The insulating adhesive is obtained, wherein the insulating adhesive comprises a ceramic slurry or a polyimide liquid; The insulating adhesive is applied to the second preset area on both sides of the second substrate using a gravure plate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as the second substrate.

[0009] Optionally, after uniformly mixing and fiberizing the positive electrode material, conductive agent, and binder, a film is formed using a film-forming device to obtain a positive electrode film, including: After the positive electrode material, conductive agent and binder are mixed evenly and fiberized, a film-forming device is used to form a film to obtain a base film. The base membrane is divided to obtain multiple positive electrode membranes with the same size as the first preset region.

[0010] Optionally, the positive electrode film is bonded to the first preset area of ​​the second substrate and subjected to composite rolling to obtain a dry-process positive electrode sheet, comprising: The positive electrode film is bonded to the side of the conductive adhesive layer of the second substrate away from the aluminum foil substrate; The bonded positive electrode film and the second substrate are subjected to composite roll pressing; The positive electrode film and the second substrate after composite rolling are separated to obtain the dry-process positive electrode sheet.

[0011] Secondly, embodiments of this application provide a dry-process positive electrode for a lithium battery, the dry-process positive electrode comprising: An aluminum foil substrate has a first preset area and a second preset area on both sides. The second preset area is adjacent to the first preset area and is located outside the second preset area. A conductive adhesive layer covers both sides of the aluminum foil substrate and is located within the first defined area; An insulating adhesive layer covers both sides of the aluminum foil substrate and is at least partially located in the second designated area, wherein the insulating adhesive layer is in contact with the edge of the conductive adhesive layer or the insulating adhesive layer partially covers the conductive adhesive layer. A positive electrode film is covered on the side of the conductive adhesive layer away from the aluminum foil substrate and located in the first preset area. The positive electrode film is in contact with the insulating adhesive layer. The positive electrode film is obtained by uniformly mixing the positive electrode material, conductive agent and binder, fiberizing them and then forming them into a film using a film forming device.

[0012] Optionally, the conductive adhesive layer is a carbon-containing adhesive layer, and the thickness of the conductive adhesive layer is 1 micrometer to 5 micrometers.

[0013] Optionally, the thickness of the insulating adhesive layer is 20-30 micrometers, and the insulating adhesive layer is obtained by drying ceramic slurry or polyimide liquid. The ceramic powder in the ceramic slurry includes one or more of alumina and boehmite materials, and the particle size of the ceramic powder is about 0.5μm-2μm. The width of the insulating adhesive layer is 1mm-5mm.

[0014] Optionally, the positive electrode substrate may contain lithium iron phosphate, lithium cobalt oxide, and nickel cobalt manganese as the main positive electrode material, conductive agent may contain one or more of conductive carbon black, carbon nanotubes, and vapor-grown carbon fibers, and binder may contain polytetrafluoroethylene.

[0015] Thirdly, embodiments of this application provide a lithium battery, which includes the aforementioned dry-process positive electrode.

[0016] The beneficial technical effects of the technical solutions provided in this application are: The lithium battery, its dry positive electrode, and the method for preparing the dry positive electrode provided in this embodiment, by pre-coating the insulating layer onto the aluminum foil substrate using gravure technology, can theoretically achieve a production speed of 80m / min-100m / min, significantly improving production efficiency and effectively reducing production costs.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A schematic flowchart illustrating a method for preparing a dry positive electrode for a lithium battery, provided in an embodiment of this application; Figure 2 A top view of an aluminum foil substrate for a dry positive electrode provided in an embodiment of this application; Figure 3 for Figure 1 The flowchart of step S1 in the dry positive electrode preparation method shown is as follows; Figure 4 A top view of a first substrate provided in an embodiment of this application; Figure 5 for Figure 4 The diagram shows a cross-sectional view of the first substrate along line AA. Figure 6 for Figure 1 The flowchart of step S2 in the dry positive electrode preparation method shown is as follows; Figure 7 A top view of a second substrate provided in an embodiment of this application; Figure 8 for Figure 7 The diagram shows a cross-section of the second substrate along line BB. Figure 9 for Figure 1 The flowchart of step S3 in the dry positive electrode preparation method shown is as follows; Figure 10 for Figure 1 The flowchart of step S4 in the dry positive electrode preparation method shown is as follows; Figure 11 A top view of a second substrate provided in an embodiment of this application; Figure 12 This is a side view of a dry positive electrode provided in an embodiment of this application.

[0019] Figure label: 10-Aluminum foil substrate; 11-Conductive adhesive layer; 12-Insulating adhesive layer; 13-Positive electrode film; 100 - First preset area; 200 - Second preset area; M1 - First substrate; M2 - Second substrate. Detailed Implementation

[0020] This application is described in detail below. Examples of embodiments of this application are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. Furthermore, detailed descriptions of known technologies that are unnecessary for the features of this application are omitted. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0022] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in the specification of this application means the presence of features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] In recent years, dry processing has attracted much attention in the battery industry. Dry electrode fabrication processes eliminate the need for solvent evaporation, thus preventing binder migration. Without compromising the mechanical or electrochemical properties of lithium-ion batteries, it can produce electrodes with extremely large thicknesses and high mass loadings, effectively overcoming the inherent limitations of traditional wet processes.

[0024] However, in the dry electrode fabrication of the positive electrode sheet, because the film is directly laminated to the edge of the aluminum foil, a ceramic insulating layer cannot be simultaneously coated at the edge of the film area. The insulating ceramic layer has a significant impact on the safety performance of the battery cell: the ceramic edge is located on the tab side of the positive electrode. During the die-cutting process, whether it's the tiny notches of the die-cutting tools or the power fluctuations of laser die-cutting, burrs can appear on the aluminum foil. The ceramic layer, with its relatively smooth surface, can make the cut surface relatively smooth after being coated on the edge of the positive electrode aluminum foil, reducing burr generation and thus decreasing the burr penetration of the electrode sheet, lowering the risk of metal foreign object puncture. Typically, in dry electrode fabrication, a layer of UV-cured insulating adhesive or hot melt adhesive is coated on the edge after film formation. This process requires a high degree of edge flatness during film formation, and the coating equipment is expensive. Furthermore, both UV and hot melt adhesives require a certain curing time, resulting in low production speed and insufficient capacity.

[0025] The lithium battery, its dry positive electrode, and the method for preparing the dry positive electrode provided in this application are intended to solve the above-mentioned technical problems of the prior art.

[0026] This application provides a method for preparing a dry positive electrode for a lithium battery. Figure 1 This illustration shows a flowchart of a method for preparing a dry positive electrode for a lithium battery according to an embodiment of this application. Figure 2 This diagram shows a top view of an aluminum foil substrate 10 for a dry-process positive electrode according to an embodiment of this application. Figure 2 As shown, the size of the aluminum foil substrate 10 can be selected according to the size requirements of the positive electrode of different lithium batteries. The aluminum foil substrate 10 has multiple first preset regions 100 and multiple second preset regions 200. In the arrangement of the preset regions, the priority should be to maximize the utilization rate of the aluminum foil substrate 10 while meeting the size requirements of the positive electrode.

[0027] like Figure 1 and Figure 2 As shown, the dry-process positive electrode preparation method provided in this embodiment includes: S1: Coat the aluminum foil substrate 10 with conductive adhesive in the first preset area 100 on both sides, and dry and roll it up to obtain an aluminum foil substrate 10 with conductive adhesive layer 11 as the first substrate M1.

[0028] Figure 3 It shows Figure 1 The flowchart shown is a schematic diagram of step S1 in the dry method for preparing a positive electrode. Figure 4 The diagram shows a top view of a first substrate M1 provided in an embodiment of this application. Figure 5 It shows Figure 4 The diagram shows a cross-sectional view of the first substrate M1 along line AA. Figures 3 to 5 As shown, in the dry positive electrode preparation method provided in this embodiment, step S1 specifically includes: S11: Using carbon-containing adhesive as the conductive adhesive, a first gravure plate is used to coat the conductive adhesive in a first preset area 100 on both sides of the aluminum foil substrate 10. The first gravure plate has multiple first grooves of the same size as the first preset area 100, and the depth of the first grooves is related to the required thickness of the conductive adhesive layer 11. Specifically, the carbon-containing adhesive is composed of a conductive agent and a binder. The conductive agent includes one or more of carbon black or carbon whiskers (VGCF), and the binder includes a resin adhesive, commonly composed of one or more of epoxy resin, modified epoxy resin, acrylic resin, polyurethane, polyamic acid, and polydopamine. Typically, the thickness change of the conductive adhesive before and after curing is between 5% and 20%, depending on the shrinkage rate, solid content, and process conditions of the conductive adhesive matrix (adhesive). For some conductive adhesives, the thickness change before and after curing may be less than 3%.

[0029] S12: The aluminum foil substrate 10 coated with conductive adhesive is dried to obtain an aluminum foil substrate 10 having a conductive adhesive layer 11 with a thickness of 1 micrometer to 5 micrometers, and then wound up to obtain an aluminum foil substrate 10 with a conductive adhesive layer 11 as the first substrate M1. Specifically, the drying temperature is 80°C to 110°C.

[0030] S2: Apply insulating adhesive to the second preset area 200 on the first substrate M1, dry and wind it to obtain an aluminum foil substrate 10 with a conductive adhesive layer 11 and an insulating adhesive layer 12 as the second substrate M2. The second preset area 200 is adjacent to the first preset area 100 and the second preset area 200 is located outside the second preset area 200. The insulating adhesive has fluidity so that the edge of the insulating adhesive layer 12 obtained after drying contacts the edge of the conductive adhesive layer 11 or the insulating adhesive layer 12 partially overlaps the conductive adhesive layer 11.

[0031] Figure 6 It shows Figure 1 The flowchart shown is a schematic diagram of step S2 in the dry positive electrode preparation method. Figure 7 The diagram shows a top view of a second substrate M2 provided in an embodiment of this application. Figure 8 It shows Figure 7 The diagram shows a cross-section of the second substrate M2 along line BB. Figures 6 to 8 As shown, in the dry positive electrode preparation method provided in this embodiment, step S2 specifically includes: S21: Obtain an insulating adhesive solution, which includes a ceramic slurry or a polyimide adhesive solution. Specifically, the ceramic slurry includes ceramic powder, which includes one or more of alumina and boehmite materials, and the particle size of the ceramic powder is approximately 0.5 μm to 2 μm.

[0032] S22: Using a second gravure plate, insulating adhesive is applied to the second preset areas 200 on both sides of the second substrate M2, and then dried and wound up to obtain an aluminum foil substrate 10 with a conductive adhesive layer 11 and an insulating adhesive layer 12, which serves as the second substrate M2. The second gravure plate has multiple second grooves, each groove being annular with the same size as the second preset area 200. The depth of the second groove is related to the required thickness of the insulating adhesive layer 12. Specifically, the insulating adhesive layer 12 is obtained after drying, and the drying temperature of the insulating adhesive is 80-110℃.

[0033] S3: After uniformly mixing the positive electrode material, conductive agent and binder and fiberizing them, a film is formed using a film forming device to obtain the positive electrode film 13.

[0034] Figure 8 It shows Figure 7 The diagram shows a cross-section of the second substrate M2 along line BB. Figure 8 As shown, in the dry-process positive electrode preparation method provided in this embodiment, step S3 specifically includes: S31: After uniformly mixing and fiberizing the positive electrode material, conductive agent, and binder, a film-forming device is used to form a basic film. Specifically, the mixture of positive electrode material, conductive agent, and binder is stirred at a speed of 500-800 r / min at a temperature below 19°C to achieve uniform mixing. Then, the temperature is increased to below 70°C, and the stirring speed is increased to 800-1500 r / min to fiberize the binder and encapsulate the positive electrode material and conductive agent.

[0035] Specifically, the main cathode material includes lithium iron phosphate, lithium cobalt oxide, and nickel cobalt manganese, the conductive agent includes one or more of conductive carbon black (SP), carbon nanotubes (CNT) and vapor-grown carbon fiber (VGCF), and the binder is polytetrafluoroethylene (PTFE).

[0036] S32: The base membrane is divided to obtain multiple positive electrode membranes 13 with the same size as the first preset region 100. Specifically, in the process of dividing the base membrane, the priority is to meet the size requirements of the positive electrode membrane 13 while maximizing the utilization rate of the base membrane.

[0037] S4: Align the positive electrode film 13 with the first preset region 100 of the second substrate M2, and perform composite rolling on the aligned positive electrode film 13 and the second substrate M2 to obtain a dry positive electrode sheet.

[0038] Figure 10 for Figure 1 The flowchart shown is a schematic diagram of step S4 in the dry positive electrode preparation method. Figure 11 This is a top view of a second substrate M2 provided in an embodiment of this application. Figure 12 This is a side view of a dry positive electrode provided in an embodiment of this application. Figures 10 to 12 As shown, in the dry positive electrode preparation method provided in this embodiment, step S4 specifically includes: S41: The positive electrode film 13 is bonded to the conductive adhesive layer 11 of the second substrate M2 on the side away from the aluminum foil substrate 10.

[0039] S42: Perform composite rolling on the bonded positive electrode film 13 and the second substrate M2.

[0040] S43: The composite rolled positive electrode film 13 and the second substrate M2 are separated to obtain a dry-process positive electrode sheet. Specifically, as follows: Figure 11 As shown, the segments are divided along the dividing lines L1-L1 and L2-L2. Mechanical or laser division can be used as needed.

[0041] The dry positive electrode preparation method provided in this embodiment, by pre-coating the insulating layer onto the aluminum foil substrate 10 using gravure technology, can theoretically achieve a production speed of 80m / min-100m / min, significantly improving production efficiency and effectively reducing production costs.

[0042] Based on the same inventive concept, embodiments of this application also provide a dry-process positive electrode for a lithium battery. For example... Figure 12 As shown, the dry positive electrode provided in this application embodiment includes an aluminum foil substrate 10, a conductive adhesive layer 11, an insulating adhesive layer 12, and a positive electrode film 13.

[0043] The aluminum foil substrate 10 includes a first preset area and a second preset area on both sides. The second preset area 200 is adjacent to the first preset area 100 and is located outside the second preset area 200.

[0044] The conductive adhesive layer 11 covers both sides of the aluminum foil substrate 10 and is located within a first defined area. Specifically, the thickness of the conductive adhesive layer 11 is 1 micrometer to 5 micrometers. The conductive adhesive layer 11 is formed by curing carbon-containing adhesive. The carbon-containing adhesive is composed of conductive agents and binders. The conductive agents include one or more of carbon black or carbon whiskers (VGCF). The binders include resin adhesives, commonly composed of one or more of epoxy resin, modified epoxy resin, acrylic resin, polyurethane, polyamic acid, and polydopamine.

[0045] An insulating adhesive layer 12 covers both sides of the aluminum foil substrate 10 and is at least partially located in the second designated area. The insulating adhesive layer 12 is in edge contact with the conductive adhesive layer 11, or the insulating adhesive layer 12 partially covers the conductive adhesive layer 11. The edge contact between the insulating adhesive layer 12 and the conductive adhesive layer 11, or the partial coverage of the conductive adhesive layer 11, has almost no impact on the performance of the positive electrode sheet, as long as the overlap is within the accuracy range. Therefore, it has good tolerance for the flowability of the insulating adhesive and the alignment accuracy during the coating process, which helps to reduce the manufacturing difficulty of the positive electrode sheet. Specifically, the width of the insulating adhesive layer is 1mm-5mm.

[0046] Specifically, the insulating adhesive includes ceramic slurry or polyimide liquid. Specifically, the ceramic slurry includes ceramic powder, which includes one or more of alumina and boehmite materials, and the particle size of the ceramic powder is approximately 0.5 μm to 2 μm.

[0047] The positive electrode film 13 covers the side of the conductive adhesive layer 11 away from the aluminum foil substrate 10 and is located in the first preset area 100. The positive electrode film 13 is in contact with the insulating adhesive layer 12. The positive electrode film 13 is obtained by uniformly mixing the positive electrode main material, conductive agent and binder, fiberizing and then forming a film using a film forming equipment.

[0048] Specifically, the main cathode material includes lithium iron phosphate, lithium cobalt oxide, and nickel cobalt manganese, the conductive agent is one or more of conductive carbon black (SP), carbon nanotubes (CNT) and vapor-grown carbon fiber (VGCF), and the binder is polytetrafluoroethylene (PTFE).

[0049] The dry positive electrode provided in this embodiment is manufactured using a dry process. During the manufacturing process, the insulating layer is pre-coated onto the aluminum foil substrate 10 using gravure technology. The theoretical production speed can reach 80m / min-100m / min, which significantly improves production efficiency and effectively reduces production costs.

[0050] Based on the same inventive concept, this application also provides a lithium battery, including any of the dry positive electrodes in the above embodiments, which has the beneficial effects of the dry positive electrodes in the above embodiments, and will not be repeated here.

[0051] By applying the embodiments of this application, at least the following beneficial effects can be achieved: The lithium battery, its dry positive electrode, and the method for preparing the dry positive electrode provided in this application embodiment, by pre-coating the insulating layer onto the aluminum foil substrate using gravure technology, can theoretically achieve a production speed of 80m / min-100m / min, significantly improving production efficiency and effectively reducing production costs.

[0052] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0053] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0054] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0055] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0056] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0057] The above are only some embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for preparing a dry positive electrode for a lithium battery, characterized in that, include: Conductive adhesive is coated in a first preset area on both sides of an aluminum foil substrate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer as a first substrate. An insulating adhesive is applied to a second preset area on the first substrate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as a second substrate. The thickness of the insulating adhesive layer is greater than the thickness of the conductive adhesive layer. The second preset area is adjacent to the first preset area and the second preset area is located outside the second preset area. The insulating adhesive has fluidity so that the edge of the insulating adhesive layer obtained after drying contacts the edge of the conductive adhesive layer or the insulating adhesive layer partially overlaps the conductive adhesive layer. After uniformly mixing and fiberizing the positive electrode material, conductive agent and binder, a film-forming device is used to form a film to obtain a positive electrode film. The positive electrode film is aligned with the first preset area of ​​the second substrate, and the aligned positive electrode film and the second substrate are subjected to composite rolling to obtain a dry positive electrode sheet.

2. The preparation method according to claim 1, characterized in that, A conductive adhesive is coated onto a first predetermined area on both sides of an aluminum foil substrate, and then dried and wound to obtain an aluminum foil substrate with a conductive adhesive layer as a first substrate, comprising: Using carbon-containing adhesive as the conductive adhesive, a first gravure plate is used to coat the conductive adhesive in a first preset area on both sides of the aluminum foil substrate. The first gravure plate is provided with a plurality of first grooves of the same size as the first preset area. The depth of the first groove is related to the required thickness of the conductive adhesive layer. The aluminum foil substrate coated with the conductive adhesive is dried to obtain an aluminum foil substrate having a conductive adhesive layer with a thickness of 1 micrometer to 5 micrometers, and then wound up to obtain an aluminum foil substrate having the conductive adhesive layer as the first substrate.

3. The preparation method according to claim 2, characterized in that, An insulating adhesive is applied to a second predetermined area on the first substrate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as a second substrate, comprising: The insulating adhesive solution is obtained, wherein the insulating adhesive solution comprises ceramic slurry or polyimide adhesive solution; The insulating adhesive is applied to the second preset area on both sides of the second substrate using a gravure plate, and then dried and wound up to obtain an aluminum foil substrate with a conductive adhesive layer and an insulating adhesive layer as the second substrate.

4. The preparation method according to claim 2, characterized in that, After uniformly mixing and fiberizing the positive electrode material, conductive agent, and binder, a film-forming device is used to form a positive electrode film, including: After the positive electrode material, conductive agent and binder are mixed evenly and fiberized, a film-forming device is used to form a film to obtain a base film. The base membrane is divided to obtain multiple positive electrode membranes with the same size as the first preset region.

5. The preparation method according to claim 4, characterized in that, The positive electrode film is bonded to the first predetermined area of ​​the second substrate and subjected to composite rolling to obtain a dry-process positive electrode sheet, comprising: The positive electrode film is bonded to the side of the conductive adhesive layer of the second substrate away from the aluminum foil substrate; The bonded positive electrode film and the second substrate are subjected to composite roll pressing; The positive electrode film and the second substrate after composite rolling are separated to obtain the dry-process positive electrode sheet.

6. A dry-process positive electrode for a lithium battery, characterized in that, include: An aluminum foil substrate has a first preset area and a second preset area on both sides. The second preset area is adjacent to the first preset area and is located outside the second preset area. A conductive adhesive layer covers both sides of the aluminum foil substrate and is located within the first defined area; An insulating adhesive layer covers both sides of the aluminum foil substrate and is at least partially located in the second designated area, wherein the insulating adhesive layer is in contact with the edge of the conductive adhesive layer or the insulating adhesive layer partially covers the conductive adhesive layer. A positive electrode film is covered on the side of the conductive adhesive layer away from the aluminum foil substrate and located in the first preset area. The positive electrode film is in contact with the insulating adhesive layer. The positive electrode film is obtained by uniformly mixing the positive electrode material, conductive agent and binder, fiberizing them and then forming them into a film using a film forming device.

7. The dry-process positive electrode according to claim 6, characterized in that, The conductive adhesive layer is a carbon-containing adhesive layer, and the thickness of the conductive adhesive layer is 1 micrometer to 5 micrometers.

8. The dry-process positive electrode according to claim 7, characterized in that, The thickness of the insulating adhesive layer is 20-30 micrometers. The insulating adhesive layer is obtained by drying ceramic slurry or polyimide liquid. The ceramic powder in the ceramic slurry includes one or more of alumina and boehmite materials. The particle size of the ceramic powder is about 0.5μm-2μm. The width of the insulating adhesive layer is 1mm-5mm.

9. The dry-process positive electrode according to claim 8, characterized in that, The cathode substrate's cathode material includes lithium iron phosphate, lithium cobalt oxide, and nickel cobalt manganese; the conductive agent includes one or more of conductive carbon black, carbon nanotubes, and vapor-grown carbon fibers; and the binder includes polytetrafluoroethylene.

10. A lithium battery, characterized in that, Includes the dry positive electrode as described in any one of claims 6-9.

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