Polymer film, pole piece and pole piece production process
By using a polymer film designed at the molecular level in power batteries, chemical bonding, electronic conductivity, and ionic conductivity functional units are achieved, solving the problems of coating quality and adhesion when coating an ultra-thin conductive carbon layer, and improving electrode peel strength and battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BATTEROTECH CO LTD
- Filing Date
- 2026-03-17
- Publication Date
- 2026-05-29
AI Technical Summary
In existing technologies, when applying ultra-thin conductive carbon layers to power batteries, the layers tend to stack, agglomerate, and gel, leading to a decrease in coating quality. Furthermore, the adhesion of the binder is only slightly improved under ultra-thin coating conditions, affecting the electrode peel strength and battery performance.
The polymer film, designed at the molecular level, forms a uniform, multifunctional polymer film by chemically bonding adhesion functional units, electronic conductivity functional units, and ionic conductivity functional units. This film is then placed between the current collector and the active material layer, thereby improving the peel strength and conductivity of the electrode.
It significantly improves the performance rate of electrodes and batteries, extends service life, and avoids the problems of difficult dispersion processing and limited adhesion improvement in the ultra-thin coating of existing technologies.
Smart Images
Figure CN122117915A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power battery technology, specifically to a polymer film, an electrode sheet, and an electrode sheet manufacturing process. Background Technology
[0002] As the application of power batteries becomes more and more widespread, the performance requirements for power batteries are also becoming higher and higher, requiring power batteries to meet higher output power and longer service life.
[0003] In existing technologies, some solutions involve coating the current collector with a layer of conductive carbon material to improve the overall performance of the power battery. Specifically, coating the current collector with conductive carbon material can improve the conductivity between the current collector and the active material, reduce contact resistance, and thus improve the rate performance of the power battery. Furthermore, the binder incorporated with the conductive carbon material enhances the peel strength of the electrode, thereby improving the capacity retention rate and extending the cycle life of the power battery. Simultaneously, the conductive carbon layer can also inhibit the growth of lithium dendrites to some extent, mitigating the lithium plating problem on the electrode.
[0004] However, in practical applications, to avoid excessive negative impacts on the structure and performance of the electrode itself, the thickness of the conductive carbon coating needs to be controlled within a relatively thin range, typically below 1 μm. At this thickness, commonly used carbon materials such as carbon nanotubes and graphene are prone to stacking, agglomeration, and gelation, causing clogging of the coating mesh and affecting coating quality. In such cases, it is generally necessary to add a highly efficient dispersant and improve the dispersion effect through methods such as ultrasonic dispersion, which is not only costly but also cumbersome. Meanwhile, the adhesive strength improvement of binders, such as polyacrylic acid, is limited under ultra-thin coating conditions, thus the improvement in electrode peel strength is also relatively limited.
[0005] Therefore, there is an urgent need to provide an electrode structure that can set a conductive layer between the current collector and the active material to improve the overall performance of the battery, while ensuring the coating quality under ultra-thin coating conditions and improving the peel strength of the electrode. Summary of the Invention
[0006] The purpose of this application is to provide a polymer film, electrode, and electrode manufacturing process that can set a conductive layer between the current collector and the active material to improve the overall performance of the battery, while ensuring the coating quality under ultra-thin coating conditions and improving the peel strength of the electrode.
[0007] To achieve the above objectives, in a first aspect, this application provides a polymer film disposed between a battery current collector and an active material layer. The polymer film includes adhesion functional units, electronically conductive functional units, and ionicly conductive functional units. The adhesion functional units include adhesion functional groups capable of interacting with the surface of the current collector. The electronically conductive functional units include electronically conductive functional groups with a conjugated structure capable of forming electron transport channels. The ionicly conductive functional units include ionicly conductive functional groups capable of dissolving and transporting metal ions. The adhesion functional units, electronically conductive functional units, and ionicly conductive functional units are chemically bonded together.
[0008] Based on the above embodiments of this application, unlike the prior art which mixes several materials with different properties at the macroscopic level to achieve different technical effects, this application integrates adhesion functional units, electronic conductivity functional units, and ion conductivity functional units on the same polymer chain through molecular design, thereby forming a multifunctional polymer film with uniform microstructure and integrated function between the current collector and the active material layer.
[0009] Specifically, the adhesion functional unit, through its adhesion functional groups, can form a strong interaction with the current collector surface, thereby effectively improving the peel strength of the electrode and mitigating the problem of active material layer shedding during battery cycling. The electronic conductivity functional unit, through the conjugated structure of its electronic conductivity functional groups, forms an electron transport channel, which can reduce the interfacial impedance during electron transport and increase the electron migration rate. Similarly, the ion conductivity functional unit, through its ion conductivity functional groups, forms an ion transport channel, which can significantly reduce the interfacial impedance during ion transport.
[0010] In summary, this application integrates adhesion, electronic conductivity, and ionic conductivity functional units at the molecular level. The synergy of these three functional units enhances the electrode's peel strength, electronic conductivity, and ionic conductivity, thereby improving the overall performance rate of the electrode and battery, extending their lifespan, and resulting in higher energy density for both the electrode and battery. Furthermore, this approach fundamentally avoids the problems inherent in existing technologies that require strong dispersion processing and yield materials with limited improvement in electrode adhesion when using macroscopically mixed functional materials for ultra-thin coating.
[0011] In some embodiments, the adhesion functional group includes any one of catechol and its derivative groups, dopamine groups, carboxyl groups, phosphate groups, mercapto groups, and silanol groups.
[0012] Based on the embodiments described above in this application, the optional types of adhesion functional groups have been listed at the molecular level. In specific applications, the adhesion functional group may include any of the above-mentioned types. For example, when the adhesion functional group includes a dopamine group, the dopamine group can generate extremely strong adhesion to the surface of various organic or inorganic materials through hydrogen bonds, thereby achieving a good adhesion effect between the adhesion functional unit and the current collector and improving the peel strength of the electrode.
[0013] In some embodiments, the adhesive functional unit material is selected from any one of polyacrylate, polymethacrylate, polyurethane, polyether, and polyvinyl alcohol.
[0014] Based on the above embodiments of this application, the types of materials that can be selected for the adhesion functional unit are listed from a macroscopic perspective. The adhesion functional unit can be prepared using any of the above materials as raw materials when preparing the polymer film.
[0015] In some embodiments, the electronically conductive functional unit material is selected from any one of poly(3,4-ethylenedioxythiophene), polypyrrole, polyaniline, and polythiophene.
[0016] Based on the above embodiments of this application, the types of materials that can be selected for the electronic conductive functional unit have been listed above. The electronic conductive functional unit can be prepared using any of the above materials as raw materials when preparing the polymer film.
[0017] In some embodiments, the ion-conducting functional unit material is selected from any one of polyethylene oxide, polypropylene oxide, polysiloxane, and polycarbonate.
[0018] Based on the above embodiments of this application, the types of materials that can be selected for the ion-conducting functional unit have been listed above. The ion-conducting functional unit can be prepared using any of the above materials as raw materials when preparing the polymer film.
[0019] In some embodiments, the adhesion functional unit, the electronically conductive functional unit, and the ionicly conductive functional unit are chemically bonded together through any one of block copolymerization, graft copolymerization, or star copolymerization.
[0020] Based on the above embodiments of this application, the adhesion functional unit, electronic conductivity functional unit and ion conductivity functional unit in this application are chemically bonded together. When specifically connected, the three can form a chain structure by block copolymerization, or a dendritic or star structure by graft copolymerization or star copolymerization.
[0021] According to a second aspect of this application, an electrode is provided, the electrode comprising a current collector, an active material layer, and the aforementioned polymer film. The active material layer is disposed on the current collector, the polymer film is coated and formed on the current collector, and the polymer film is located between the current collector and the active material layer.
[0022] Based on the embodiments described above, the electrode provided in this application includes the aforementioned polymer film, which is disposed between the current collector and the active material layer of the electrode. Through this arrangement, the adhesion functional unit, the electronic conductivity functional unit, and the ion conductivity functional unit are chemically bonded together. The cooperation of these three functional units enhances the electrode's peel strength, electronic conductivity, and ion conductivity, thereby improving the overall performance rate of the electrode and the battery, extending its service life, and resulting in a higher energy density for both the electrode and the battery. Simultaneously, this arrangement fundamentally avoids the problems of requiring strong dispersion and limited improvement in adhesion that exist in existing technologies when mixing several functional materials at a macroscopic level to achieve ultra-thin coating.
[0023] In some embodiments, the thickness of the polymer film is H, where 10 nm ≤ H ≤ 1000 nm.
[0024] Based on the embodiments described above, the thickness of the polymer film is limited to a relatively thin range. Since the polymer film is disposed between the current collector and the active material layer, the thin polymer film can both enhance the electrode peel strength and conductivity, and avoid affecting the connection and conduction between the active material layer and the current collector.
[0025] According to a third aspect of this application, an electrode manufacturing process is provided for manufacturing the aforementioned electrode, the electrode manufacturing process comprising the following steps: Polymer film preparation: A polymer containing adhesive functional units, electronic conductive functional units and ionic conductive functional units is prepared, and the polymer is coated on a current collector to form a polymer film with a thickness between 10 nm and 1000 nm.
[0026] An active material layer is coated to prepare an active material slurry, which is then coated onto a polymer film to form an active material layer, thus obtaining the electrode rough material.
[0027] Electrode preparation involves rolling and cutting raw electrode material to obtain electrode sheets.
[0028] Based on the above embodiments of this application, the preparation process of the electrode sheet is disclosed. The electrode sheet as a whole includes three layers stacked in sequence: a current collector, a polymer film, and an active material layer. Therefore, in the preparation process, the polymer film is coated and formed first, followed by the coating of the active material layer, and finally the finished electrode sheet is obtained through rolling and cutting steps.
[0029] In some embodiments, during the polymer film preparation step, a polymer comprising adhesive functional units, electronically conductive functional units, and ionicly conductive functional units is prepared using living / controlled polymerization technology. The obtained polymer is then dissolved in a solvent to prepare a polymer slurry, which is subsequently coated onto a current collector to form a polymer film. Alternatively, After the adhesion functional unit is dissolved in a solution, it is coated onto the current collector. Subsequently, the electronically conductive and ionicly conductive functional units are polymerized with the adhesion functional unit through a liquid-phase or gas-phase polymerization reaction to form a polymer film.
[0030] Based on the embodiments described above, two methods for coating polymer films onto current collectors are disclosed. In one method, a polymer in which three functional units are chemically bonded together is first prepared. The polymer is then dissolved in a solution to form a slurry, which is then coated onto the surface of the current collector using methods such as spraying or micro-gravure roller coating. In another method, an adhesive functional unit with excellent adhesion properties is first prepared into a slurry and coated onto the current collector using methods such as spraying. Subsequently, electronically conductive and ionicly conductive functional units are polymerized with the adhesive functional units through a polymerization reaction, ultimately chemically bonding together to form a polymer film on the surface of the current collector.
[0031] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description
[0032] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the electrode provided in the embodiment of this application.
[0033] Figure 2 This is a schematic flowchart of the electrode manufacturing process provided in the embodiments of this application.
[0034] Figure 3 This is a comparison diagram of the interface impedance measured in the embodiments and comparative examples of this application.
[0035] Figure 4 This is a comparison diagram of the peel strength measured in the embodiments and comparative examples of this application.
[0036] Explanation of reference numerals in the attached figures 1. Current collector; 2. Active material layer; 3. Polymer membrane. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0039] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0040] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0041] In the description of this application, it should be noted that, unless otherwise stated, the terms "inner," "outer," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used 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 on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0042] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0043] In existing technologies, some solutions involve coating the current collector with a layer of conductive carbon material to improve the overall performance of the power battery. Specifically, coating the current collector with conductive carbon material can improve the conductivity between the current collector and the active material, reduce contact resistance, and thus improve the rate performance of the power battery. Furthermore, the binder incorporated with the conductive carbon material enhances the peel strength of the electrode, thereby improving the capacity retention rate and extending the cycle life of the power battery. Simultaneously, the conductive carbon layer can also inhibit the growth of lithium dendrites to some extent, mitigating the lithium plating problem on the electrode.
[0044] However, in practical applications, to avoid excessive negative impacts on the structure and performance of the electrode itself, the thickness of the conductive carbon coating needs to be controlled within a relatively thin range, typically below 1 μm. At this thickness, commonly used carbon materials such as carbon nanotubes and graphene are prone to stacking, agglomeration, and gelation, causing clogging of the coating mesh and affecting coating quality. In such cases, it is generally necessary to add a highly efficient dispersant and improve the dispersion effect through methods such as ultrasonic dispersion. Therefore, this coating method is not only costly but also cumbersome. Furthermore, the adhesive strength improvement of binders, such as polyacrylic acid, is limited under ultra-thin coating conditions, thus the improvement in electrode peel strength is also relatively limited.
[0045] Therefore, there is an urgent need to provide an electrode structure that can set a conductive layer between the current collector and the active material to improve the overall performance of the battery, while ensuring the coating quality under ultra-thin coating conditions and improving the peel strength of the electrode.
[0046] To address the aforementioned problems in the prior art, this application provides a polymer film 3, as shown in the reference. Figure 1 As shown, the polymer film 3 is disposed between the battery current collector 1 and the active material layer 2. The polymer film 3 includes adhesion functional units, electronic conductivity functional units, and ion conductivity functional units. The adhesion functional units include adhesion functional groups that can form strong interactions with the surface of the current collector 1. The electronic conductivity functional units include electronic conductivity functional groups with a conjugated structure that can form electron transport channels. The ion conductivity functional units include ion conductivity functional groups that can dissolve and transport metal ions. The adhesion functional units, electronic conductivity functional units, and ion conductivity functional units are chemically bonded together.
[0047] Based on the above embodiments of this application, unlike the prior art which mixes several materials with different properties at the macroscopic level to achieve different technical effects, this application integrates adhesion functional units, electronic conductivity functional units and ion conductivity functional units on the same polymer chain through molecular design, thereby forming a multifunctional polymer film 3 with uniform microstructure and integrated function between the current collector 1 and the active material layer 2.
[0048] Specifically, the adhesion functional unit, through its adhesion functional groups, forms a strong interaction with the surface of the current collector 1, thereby effectively improving the peel strength of the electrode and mitigating the problem of active material layer 2 shedding during battery cycling. The electronic conductivity functional unit, through the conjugated structure of its electronic conductivity functional groups, forms an electron transport channel, which reduces the interfacial impedance during electron transport and increases the electron migration rate. Similarly, the ion conductivity functional unit, through its ion conductivity functional groups, forms an ion transport channel, which significantly reduces the interfacial impedance during ion transport.
[0049] In summary, this application integrates adhesion, electronic conductivity, and ionic conductivity functional units at the molecular level. The synergy of these three functional units enhances the electrode's peel strength, electronic conductivity, and ionic conductivity, thereby improving the overall performance rate of the electrode and the battery, and extending its lifespan. Furthermore, this approach fundamentally avoids the problems inherent in existing technologies that require strong dispersion processing and result in limited improvement in electrode adhesion when mixing several functional materials at the macroscopic level for ultra-thin coating.
[0050] Furthermore, the polymer film 3 described above is obtained through molecular-level design in this application. By placing the polymer film 3 between the current collector 1 and the active material layer 2 of the electrode, the peel strength and conductivity of the electrode are improved. In specific applications, as long as the functional requirements of each functional unit are met and each functional unit can be polymerized, there are no specific limitations on the specific composition of the polymer film 3. Simultaneously, the polymer film 3 can be applied to various anodes, such as anodes with graphite as the active material or anodes with silicon as the active material. Based on the above configuration, the polymer film 3 disclosed in this application possesses good versatility and universality, and has promising application prospects.
[0051] In some embodiments of this application, the adhesion functional group may include any one of catechol and its derivative groups, dopamine groups, carboxyl groups, phosphate groups, mercapto groups, and silanol groups.
[0052] Based on the above embodiments of this application, the optional types of adhesion functional groups are listed at the molecular level. In specific use, the adhesion functional groups may include any of the above types.
[0053] For example, when the adhesion functional group includes a dopamine group, the dopamine group can generate a strong adhesion force with the surface of various organic or inorganic materials by means of hydrogen bonds, thereby achieving a good adhesion effect between the adhesion functional unit and the current collector 1 and improving the peel strength of the electrode.
[0054] Furthermore, the adhesion functional groups in this application are not limited to the above components. Other functional groups that can form strong interactions with the surface of the current collector 1 and can be applied to the electrode can also be used as adhesion functional groups. The specific selection can be made according to the actual situation, and this application does not impose any specific restrictions on this.
[0055] In some embodiments of this application, the adhesive functional unit material may be selected from any one of polyacrylate, polymethacrylate, polyurethane, polyether, and polyvinyl alcohol.
[0056] Based on the above embodiments of this application, the types of materials that can be selected for the adhesion functional unit are listed from a macroscopic perspective. The adhesion functional unit can be prepared using any of the above materials as raw materials when the polymer film 3 is prepared.
[0057] Specifically, taking polyacrylate as an example, polyacrylate itself possesses carboxyl groups, which can stably bind to the surface of current collector 1 through hydrogen bonds or coordination bonds, forming a strong anchor. Simultaneously, polyacrylate is easily dissolved in solution to form a uniform and dense film, facilitating subsequent film formation through coating or other methods. Furthermore, polyacrylate readily copolymerizes with other functional groups, facilitating the bonding of adhesion functional units with electronically conductive and ionicly conductive functional units.
[0058] In some embodiments of this application, the electronically conductive functional unit material may be selected from any one of poly(3,4-ethylenedioxythiophene), polypyrrole, polyaniline, and polythiophene.
[0059] Based on the above embodiments of this application, the types of materials that can be selected for the electronic conductive functional unit have been listed above. When preparing the polymer film 3, the electronic conductive functional unit can be prepared using any of the above materials as raw materials.
[0060] Taking polypyrrole as an example, polypyrrole is easily polymerized with other functional units, which facilitates the processing and molding of polymer film 3. At the same time, polypyrrole has good electronic conductivity, and its application in polymer film 3 can significantly improve the electronic conductivity of the electrode.
[0061] Similarly, in some embodiments of this application, the ion-conducting functional unit material may be selected from any one of polyethylene oxide, polypropylene oxide, polysiloxane, and polycarbonate.
[0062] Based on the above embodiments of this application, the types of materials that can be selected for the ion-conducting functional unit have been listed above. The ion-conducting functional unit can be prepared using any of the above materials as raw materials when the polymer film 3 is prepared.
[0063] Taking polyethylene oxide as an example, polyethylene oxide has good lithium-ion dissolution ability and good lithium-ion conductivity. Applying polyethylene oxide to polymer film 3 can significantly improve the lithium-ion conductivity of the electrode.
[0064] Furthermore, it should be noted that when selecting specific materials, the materials for the adhesion functional unit, electronic conductivity functional unit, and ion conductivity functional unit are not limited to the various materials listed above. Any material that has the above-mentioned functional effects and can be used in the electrode can be selected. The specific selection can be made according to the actual situation, and this application does not impose any specific restrictions on this.
[0065] In some embodiments of this application, the adhesion functional unit, the electronically conductive functional unit, and the ionicly conductive functional unit can be chemically bonded together by any one of block copolymerization, graft copolymerization, or star copolymerization.
[0066] Based on the above embodiments of this application, the adhesion functional unit, electronic conductivity functional unit and ion conductivity functional unit in this application are chemically bonded together. When specifically connected, the three can form a chain structure by block copolymerization, or a dendritic or star structure by graft copolymerization or star copolymerization.
[0067] Specifically, taking block copolymerization as an example, adhesive functional units, electronically conductive functional units, and ionicly conductive functional units are sequentially connected and chemically bonded to form a linear triblock copolymer. The specific preparation process can be selected according to actual conditions, and this application does not impose specific limitations on this.
[0068] Based on the above technical solutions, this application also provides an electrode sheet, as shown in the following embodiments. Figure 1 As shown, the electrode includes a current collector 1, an active material layer 2, and the aforementioned polymer film 3. The active material layer 2 is disposed on the current collector 1, the polymer film 3 is coated and formed on the current collector 1, and the polymer film 3 is located between the current collector 1 and the active material layer 2.
[0069] Based on the embodiments described above, the electrode provided in this application includes the aforementioned polymer film 3, which is disposed between the current collector 1 and the active material layer 2 of the electrode. Through this arrangement, the adhesion functional unit, the electronic conductivity functional unit, and the ion conductivity functional unit are chemically bonded together. The cooperation of these three functional units enhances the peel strength, electronic conductivity, and ion conductivity of the electrode, thereby improving the overall performance rate of the electrode and the battery, and extending its service life. Simultaneously, this arrangement fundamentally avoids the problems of requiring strong dispersion and limited improvement in adhesion that exist in existing technologies when mixing several functional materials at a macroscopic level to achieve ultra-thin coating.
[0070] Specifically, in some embodiments of this application, the electrode can also be double-sided coated, that is, an active material layer 2 is provided on both sides of the current collector 1 in the thickness direction, and a polymer film 3 is provided on both sides of the current collector 1 accordingly.
[0071] Furthermore, the specific materials of the current collector 1 and the active material layer 2 can be selected with reference to existing technologies. For example, the current collector 1 can be made of copper foil, and the active material layer 2 can be made of graphite as the main material. The specific materials can be selected according to the type of battery and electrode, and this application does not impose any specific restrictions on them.
[0072] In some embodiments of this application, the thickness of the polymer film 3 is H, where 10nm ≤ H ≤ 1000nm.
[0073] Based on the embodiments described above, by limiting the thickness of the polymer film 3, the thickness of the polymer film 3 is restricted to a relatively thin range. Since the polymer film 3 is disposed between the current collector 1 and the active material layer 2, the thin polymer film 3 can both enhance the electrode peel strength and conductivity, and avoid affecting the connection and conduction between the active material layer 2 and the current collector 1.
[0074] In practical applications, the specific thickness of the polymer film 3 can be set to multiple specific thicknesses such as 10nm, 100nm, 300nm, 700nm, 900nm, and 1000nm. The specific thickness can be selected according to factors such as the size of the electrode. This application does not impose specific restrictions on this.
[0075] Based on the above technical solutions, this application also provides an electrode manufacturing process, referring to... Figure 2 As shown, the electrode used to manufacture the above-mentioned electrode includes the following steps in its manufacturing process: S001 Polymer film preparation: A polymer containing adhesion functional units, electronic conductivity functional units and ion conductivity functional units is prepared, and the polymer is coated on current collector 1 to form a polymer film 3 with a thickness between 10 nm and 1000 nm.
[0076] The active material layer S002 is coated to prepare an active material slurry, which is then coated on the polymer film 3 to form an active material layer, thereby obtaining the electrode coarse material.
[0077] S003 electrode preparation involves rolling and cutting raw electrode material to obtain the electrode sheet.
[0078] Based on the above embodiments of this application, the preparation process of the electrode sheet is disclosed. The electrode sheet as a whole includes three layers stacked in sequence: a current collector 1, a polymer film 3, and an active material layer 2. Therefore, in the preparation process, the polymer film 3 is coated and formed first, followed by the coating of the active material layer 2, and finally the finished electrode sheet is obtained through rolling and cutting steps.
[0079] Specifically, the preparation and coating process of the active material layer 2 can be set with reference to existing technologies. For example, graphite is used as the main material, and conductive agents, dispersants, and binders are added in a certain proportion, which are then dissolved to form an active material slurry, and then coated to form the active material layer 2. Furthermore, in the electrode preparation steps, the specific processes and parameters of electrode rolling and cutting can also be set with reference to existing technologies, and this application does not impose specific limitations on them.
[0080] Furthermore, in some embodiments of this application, in the polymer film 3 preparation step, a polymer comprising adhesion functional units, electronic conductivity functional units, and ionic conductivity functional units is prepared using living / controlled polymerization technology. The obtained polymer is then dissolved in a solvent to obtain a polymer slurry, which is subsequently coated onto the current collector 1 to form the polymer film 3. Alternatively, After the adhesion functional unit is dissolved in the solution, it is coated onto the current collector 1. Then, the electronic conductivity functional unit and the ion conductivity functional unit are polymerized with the adhesion functional unit through liquid phase or gas phase polymerization reaction to form a polymer film 3.
[0081] Based on the embodiments described above, two methods for coating a polymer film 3 onto a current collector 1 are disclosed. In one method, a polymer in which three functional units are chemically bonded together is first prepared. The polymer is then dissolved in a solution to form a slurry, which is then coated onto the surface of the current collector 1 using methods such as spraying or micro-gravure roller coating. In another method, an adhesive functional unit with excellent adhesion properties is first prepared into a slurry and coated onto the current collector 1 using methods such as spraying. Then, an electronically conductive functional unit and an ionicly conductive functional unit are polymerized with the adhesive functional unit through a polymerization reaction, ultimately chemically bonded together to form a polymer film 3 on the surface of the current collector 1.
[0082] Specifically, when using a coating method that first prepares the polymer, the polymer can be prepared using living / controlled polymerization technology, and the specific preparation process can be set up with reference to existing technologies. For example, firstly, an adhesion functional unit macromolecular initiator with an active group at one end is synthesized through methods such as atom transfer radical polymerization (ATRP). Then, the monomer polymerization of the electronically conductive functional unit is initiated through electrochemical polymerization to obtain a diblock copolymer of the adhesion functional unit and the electronically conductive functional unit. Subsequently, the end functionalization of the diblock copolymer is performed to initiate the ring-opening polymerization of the monomer of the ionically conductive functional unit, resulting in a ternary block copolymer of the adhesion functional unit, the electronically conductive functional unit, and the ionically conductive functional unit. The adhesion functional unit material can be polyacrylate, the electronically conductive functional unit material can be 3,4-ethylenedioxythiophene, and the ionically conductive functional unit material can be ethylene oxide.
[0083] The performance of the electrode prepared by the electrode manufacturing process in this application will be further compared and illustrated below through a specific embodiment and a comparative example.
[0084] Example The electrode structure was prepared using the electrode manufacturing process provided in this application, and then interfacial impedance and peel strength tests were performed, specifically including: (1) Polymer preparation First, a macromolecular initiator with an active group at one end of the adhesive functional unit is synthesized from polyacrylate by atom transfer radical polymerization. Then, the monomer of 3,4-ethylenedioxythiophene is polymerized by electrochemical polymerization to obtain a diblock copolymer of adhesive and electronically conductive functional units. Subsequently, the end of the diblock copolymer is functionalized to initiate the ring-opening polymerization of ethylene oxide monomers to obtain a ternary block copolymer of adhesive, electronically conductive, and ionicly conductive functional units.
[0085] (2) Polymer film coating The prepared ternary block copolymer was dissolved in a solution to form a polymer slurry, which was then coated onto the current collector 1 using a micro-gravure roller coating method. After drying, a polymer film 3 with a thickness of 500 nm was formed. The current collector 1 was a copper foil with a thickness of 10 μm.
[0086] (3) Coating of active material layer Using graphite as the main material, styrene butadiene rubber (SBR) is added as a binder, carboxymethyl cellulose (CMC) is added as a dispersant, and conductive carbon black is added as a conductive agent. The above materials are mixed and added to a solution to obtain an active material slurry. The active material slurry is then coated onto a polymer film 3 by extrusion coating and dried to form an active material layer 2, thereby obtaining the electrode rough material.
[0087] (4) Electrode preparation The raw material for the electrode is rolled and compacted to a density of 1.65 g / cc, and then cut to obtain the negative electrode.
[0088] (5) Performance testing First, the peel strength of the prepared negative electrode sheet was tested. Then, the prepared negative electrode sheet was assembled with the positive electrode sheet to prepare a pouch cell, and electrochemical impedance spectroscopy (EIS) was performed.
[0089] Comparative Example The preparation and testing process of the electrode in the comparative example is basically the same as that in the example, except that the current collector 1 and the active material layer 2 in the comparative example are coated with a physical mixture of conductive carbon black and acrylate.
[0090] refer to Figure 3 and Figure 4 As shown, in which, Figure 3 The Nyquist plots were obtained from electrochemical impedance spectroscopy measurements for the examples and comparative examples. Figure 4 The results of peel strength tests were obtained for the examples and comparative examples.
[0091] Specifically, refer to Figure 3 As shown in the figure, the horizontal axis represents the real part of the impedance Z', and the vertical axis represents the negative value of the imaginary part of the impedance -Z''. It can be seen from the figure that the interfacial impedance measured in this embodiment is significantly smaller than that in the comparative example. Therefore, by providing the aforementioned polymer film 3 between the current collector 1 and the active material layer 2, compared to the prior art method of physically mixing and coating several functional materials at a macroscopic level, the polymer film 3 of this application can significantly improve the electronic and ionic conductivity of the electrode and reduce the interfacial impedance of the electrode and the battery as a whole.
[0092] refer to Figure 4As can be seen from the above, the peel force of the embodiments and the comparative examples were tested twice. The peel force of the embodiments was 19 N / m in both tests, while the results of the comparative examples were 12 N / m and 13 N / m in the two tests, respectively. It can be seen that by setting the above-mentioned polymer film 3 between the current collector 1 and the active material layer 2, and utilizing the adhesion functional unit in the polymer film 3, the peel strength of the electrode can be significantly improved.
[0093] In summary, this application provides a polymer film 3 between the current collector 1 and the active material layer 2. The polymer film 3 chemically bonds the adhesion functional unit, the electronic conductivity functional unit, and the ion conductivity functional unit into one unit. The three functional units work together to improve the peel strength of the electrode, as well as the electronic conductivity and ion conductivity, thereby improving the performance rate of the electrode and the battery as a whole and extending its service life.
[0094] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.
[0095] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.
[0096] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.
Claims
1. A polymer membrane disposed between a battery current collector and an active material layer, characterized in that, The polymer film comprises: An adhesion functional unit includes an adhesion functional group, which is capable of interacting with the current collector surface; An electronically conductive functional unit includes an electronically conductive functional group, wherein the electronically conductive functional group has a conjugated structure and is capable of forming an electron transport channel; An ion-conducting functional unit includes ion-conducting functional groups, which are capable of dissolving and transporting metal ions. The adhesion functional unit, the electronic conductivity functional unit, and the ion conductivity functional unit are chemically bonded together.
2. The polymer film according to claim 1, characterized in that, The adhesion functional group includes any one of catechol and its derivative groups, dopamine groups, carboxyl groups, phosphate groups, mercapto groups, and silanol groups.
3. The polymer film according to claim 2, characterized in that, The material of the adhesion functional unit is selected from any one of polyacrylate, polymethyl methacrylate, polyurethane, polyether, and polyvinyl alcohol.
4. The polymer film according to claim 1, characterized in that, The electronically conductive functional unit material is selected from any one of poly(3,4-ethylenedioxythiophene), polypyrrole, polyaniline, and polythiophene.
5. The polymer film according to claim 1, characterized in that, The material of the ion-conducting functional unit is selected from any one of polyethylene oxide, polypropylene oxide, polysiloxane, and polycarbonate.
6. The polymer film according to any one of claims 1-5, characterized in that, The adhesion functional unit, the electronic conductivity functional unit, and the ion conductivity functional unit are chemically bonded together through any one of block copolymerization, graft copolymerization, or star copolymerization.
7. An electrode sheet, characterized in that, The electrode includes: current collector; An active material layer is disposed on the current collector; and, The polymer membrane according to any one of claims 1-6, wherein the polymer membrane is coated and formed on the current collector, and the polymer membrane is located between the current collector and the active material layer.
8. The electrode sheet according to claim 7, characterized in that, The thickness of the polymer film is H, where 10nm ≤ H ≤ 1000nm.
9. A process for manufacturing an electrode sheet, used to manufacture the electrode sheet as described in claim 7 or 8, characterized in that, The electrode manufacturing process includes the following steps: Polymer film preparation: A polymer containing the adhesion functional unit, the electronic conductivity functional unit and the ion conductivity functional unit is prepared, and the polymer is coated on the current collector to form a polymer film with a thickness between 10 nm and 1000 nm. An active material layer is coated to prepare an active material slurry, which is then coated onto a polymer film to form an active material layer, thus obtaining a crude electrode material. Electrode preparation involves rolling and cutting raw electrode material to obtain electrode sheets.
10. The electrode manufacturing process according to claim 9, characterized in that, In the polymer film preparation step, a polymer containing the adhesion functional unit, the electronic conductivity functional unit and the ion conductivity functional unit is prepared by using active / controlled polymerization technology. Then, the prepared polymer is dissolved in a solvent to prepare a polymer slurry. The polymer slurry is then coated on the current collector to form the polymer film. or, The adhesion functional unit is dissolved in a solution and then coated onto the current collector. Subsequently, the electronically conductive functional unit and the ionicly conductive functional unit are polymerized with the adhesion functional unit through a liquid-phase or gas-phase polymerization reaction to form the polymer film.