Flexible electrode assembly manufacturing method, battery cell, battery device, electric device

Abstract

The application discloses a flexible electrode assembly preparation method, a battery monomer, a battery device and an electric equipment. The flexible electrode assembly preparation method comprises the following steps: coating a negative active material coating on the outer peripheral surface of a negative current collector and coating a positive active material coating on the outer peripheral surface of a positive current collector; scraping off the negative active material coating on at least one end of a negative electrode to form a first bare area and taking the negative active material coating as a winding center line; electrically connecting a negative tab to the first bare area in a winding mode; winding a diaphragm on the outer peripheral surface of the negative electrode; taking the winding center line as a winding axis, winding a positive electrode in a spiral mode, scraping off the positive active material coating on at least one end of the positive electrode to form a second bare area; electrically connecting a positive tab to the second bare area in a winding mode; and winding the diaphragm on the outer peripheral surface of the positive electrode.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a method for preparing a flexible electrode assembly, a battery cell, a battery device, and an electrical device. Background Technology

[0002] With the rapid development of emerging industries such as wearable devices, flexible displays, and smart healthcare, flexible, lightweight, and deformable energy storage devices have become an industry necessity. Fiber-based flexible batteries, with their advantages of bendability, adaptability, and thinness, have become a core research and industrialization direction in the field of flexible batteries. To simultaneously meet the requirements of complex deformation adaptability and high-capacity energy storage, fiber-based flexible batteries typically employ sheet-like or filament-like composite ultra-fine metal current collector structures, and construct electrode assemblies through multi-layered electrode and separator winding. Currently, fiber-based flexible batteries usually first complete the winding of multiple layers of electrode wires and separators to form a prototype electrode assembly, and then connect the positive and negative tabs to the corresponding positive and negative electrode wires. This process easily leads to problems such as poor contact, loose connections, or misalignment of the tabs, and the current collector is prone to breakage during the connection process. Summary of the Invention

[0003] The main objective of this application is to provide a method for preparing a flexible electrode assembly, a battery cell, a battery device, and an electrical device, in order to solve the technical problems that existing fiber flexible batteries are prone to poor contact, loosening and misalignment when the tabs are transferred after multi-layer winding molding, and that the transfer process is prone to current collector breakage and poor connection reliability.

[0004] To achieve the above objectives, a first aspect of this application provides a method for fabricating a flexible electrode assembly, comprising: The outer peripheral surface of the negative current collector is coated with a negative electrode active material coating, and the outer peripheral surface of the positive current collector is coated with a positive electrode active material coating. The coating of the negative electrode active material at at least one end of a negative electrode is scraped off to form a first exposed area, and the negative electrode is used as the winding center line. The negative electrode tab is electrically connected to the first exposed area by winding it around; A diaphragm is wound around the outer peripheral surface of the negative electrode; Using the winding center line as the winding axis, the positive electrode is wound in a spiral manner, and the coating of the positive electrode active material at at least one end of the positive electrode is scraped off to form a second exposed area. The positive electrode tab is electrically connected to the second exposed area in a wound manner; A diaphragm is wound around the outer peripheral surface of the positive electrode.

[0005] The technical effects of this application are as follows: This application shortens the ion transport path by using a negative electrode as the winding center line and winding the positive electrode in a spiral manner, while simultaneously winding a diaphragm between adjacent positive and negative electrodes. The adaptive nature of the spiral structure also improves the overall bending and torsion performance. Furthermore, the negative electrode tab is electrically connected to the first exposed area by winding before the diaphragm is wound, and the positive electrode tab is electrically connected to the second exposed area by winding before the diaphragm is wound. This method embeds the electrode tab transfer process within the winding process, enabling both the electrode assembly and the diaphragm formed after winding to exert radial constraint forces on the electrode tab connection position. This improves the reliability of the electrode tab electrical connection, reduces the possibility of loosening, and enhances overall connection reliability.

[0006] In some embodiments, electrically connecting the negative electrode tab to the first exposed area in a wound manner includes: The negative electrode tab is electrically connected to the first exposed area in a spiral winding manner; And / or, electrically connecting the positive electrode tab to the second exposed area in a wound manner, including: The positive electrode tab is electrically connected to the second exposed area in a spiral winding manner.

[0007] In some embodiments, the number of negative electrodes is one, and the number of positive electrodes is multiple. Using a winding center line as the winding axis, the positive electrodes are wound in a spiral manner. The positive electrode active material coating at at least one end of the positive electrode is scraped off to form a second exposed area, including: Using the winding center line as the winding axis, first wind a layer of negative electrode in a spiral manner, and then wind multiple positive electrodes in a parallel spiral manner. Scrape off the positive active material coating at the same end of each positive electrode to form a second exposed area.

[0008] In some embodiments, both the number of negative electrodes and the number of positive electrodes are multiple; after winding a diaphragm around the outer peripheral surface of the positive electrode, the method for fabricating the flexible electrode assembly further includes: Using the winding center line as the winding axis, the remaining negative electrodes and the remaining positive electrodes are spirally wound in an alternating manner to form a multilayer negative electrode and a multilayer positive electrode arranged radially staggered along the winding center line, and a diaphragm is wound between adjacent layers of negative electrodes and layers of positive electrodes. After each layer of negative electrode is wound, the coating of the negative active material at at least one end of the negative electrode layer is scraped off to form a first exposed area. The negative electrode tab is electrically connected to the first exposed area by winding, and then the separator is wound. After each layer of positive electrode is wound, the coating of the positive active material at at least one end of the positive electrode layer is scraped off to form a second exposed area. The positive electrode tab is electrically connected to the second exposed area by winding, and then the separator is wound.

[0009] In some embodiments, the remaining negative current collectors other than the winding center line are of wire or strip structure.

[0010] In some embodiments, each layer contains multiple negative electrodes, and the remaining negative and positive electrodes are spirally wound in an alternating manner with the winding center line as the winding axis, including: spirally winding multiple negative electrodes in the same layer in parallel with the winding center line as the winding axis; and / or Each layer contains multiple positive electrodes. The remaining negative and positive electrodes are spirally wound in an alternating manner, with the winding center line as the winding axis. This includes spirally winding multiple positive electrodes in the same layer in parallel, with the winding center line as the winding axis.

[0011] In some embodiments, the method for fabricating a flexible electrode assembly further includes: After all the positive and negative electrodes are wound, at least one layer of diaphragm is spirally wound around the center line of the winding, so that the diaphragm is located on the outermost layer of all the positive and negative electrodes. The tail end of the outermost diaphragm is fixed with insulating tape.

[0012] In some embodiments, a diaphragm is wound around the outer peripheral surface of the negative electrode, including: The diaphragm is configured to cover the first exposed area of ​​the corresponding negative electrode; And / or, a diaphragm is wound around the outer peripheral surface of the positive electrode, comprising: The diaphragm is configured to cover the second exposed area of ​​the corresponding positive electrode.

[0013] In some embodiments, before electrically connecting the negative electrode tab to the first exposed area, the method for fabricating the flexible electrode assembly further includes: The surface of the first exposed area is cleaned to remove impurities and oxide layers. And / or, before electrically connecting the positive electrode tab to the second exposed area, the preparation method further includes: The surface of the second exposed area is cleaned to remove impurities and oxide layers.

[0014] In some embodiments, electrically connecting the negative electrode tab to the first exposed area includes: The negative electrode tab is secured to the first exposed area by wrapping it around the electrode. Or, electrically connecting the positive electrode tab to the second exposed area, including: Secure the positive electrode tab to the second exposed area by wrapping it around.

[0015] In some embodiments, the length of the first exposed area ranges from 5mm to 15mm; and / or, the length of the second exposed area ranges from 5mm to 15mm.

[0016] In some embodiments, in any two adjacent layers of positive and negative electrodes, the electrode located in the inner layer is the first electrode, and the electrode located in the outer layer of the first electrode is the second electrode. During the winding process, the tension of the second electrode is controlled to be less than that of the first electrode.

[0017] In some embodiments, the positive current collector has a strip structure or a filament structure.

[0018] A second aspect of this application provides a single battery cell, comprising: Encapsulation layer with a receiving cavity; The electrode assembly is prepared using the flexible electrode assembly preparation method described in the first aspect, and the electrode assembly is located within the receiving cavity.

[0019] A third aspect of this application provides a battery device comprising at least one battery cell as described in the second aspect.

[0020] A fourth aspect of this application provides an electrical device including the battery device described in the third aspect, the battery device being used to provide electrical energy to the electrical device. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 A flowchart illustrating a method for fabricating a flexible electrode assembly, provided for some embodiments of this application; Figure 2 A partial structural schematic diagram of an electrode assembly in a battery cell provided for some embodiments of this application; Figure 3 This is a cross-sectional view of a battery cell with its negative electrode perpendicular to the center, provided for some embodiments of this application.

[0022] The reference numerals in the accompanying drawings for the specific implementation methods are as follows: 100. Electrode assembly; 10. Positive electrode; 11. Positive electrode active material layer; 12. Positive current collector; 20. Negative electrode; 21. Negative electrode active material layer; 22. Negative current collector; 30. Separator; 200. Encapsulation layer. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0026] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0027] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linked," and "socketing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] Currently, to achieve high capacity and high flexibility, fiber flexible batteries generally adopt a structure of spiral winding of multiple strands of ultra-fine metal current collectors. Typically, the electrode body is first wound into shape, and then the tabs are transferred. Because the multiple current collectors are compacted, the space reserved at their ends is small. Since the diameter of the current collector is small, generally 0.02 mm to 0.20 mm, the wrapping of multiple layers of electrode wires and separators is completed first to form the prototype of the electrode assembly. Then, the positive and negative tabs are connected to the corresponding positive and negative electrode wires. This can easily make the tab transfer difficult, and after the transfer, the tabs are prone to poor contact and breakage at the connection point.

[0029] This application uses a negative electrode as the winding center line, and multiple positive electrodes and the remaining negative electrode are spirally wound around the outer periphery of this center line. A diaphragm is then spirally wound around this center line as the axis, reliably separating circumferentially adjacent positive and negative electrodes to prevent short circuits. Furthermore, before each winding of the diaphragm, the active material layer at the end of the positive or negative electrode to be covered by the diaphragm (the outermost electrode before diaphragm winding, which may be either positive or negative; if only one negative electrode is not wrapped with the diaphragm, only the negative electrode active material layer at its end is scraped off) is removed, exposing the current collector. Before each winding of the diaphragm, the ends of the outermost positive or negative electrodes are exposed and unconstrained, facilitating connection to the tabs. In addition, the tabs can be spirally wound around the corresponding exposed areas to achieve electrical connection, reducing the possibility of connection failure due to small contact area, thus improving connection reliability, and increasing the current-carrying area at the connection point. Finally, wrapping the diaphragm enhances the constraint at the connection point, further improving the reliability of the tab connection and preventing short circuits caused by tabs of different polarities bridging.

[0030] The following description uses a method for preparing a flexible electrode assembly according to some embodiments of this application as an example.

[0031] This application discloses a method for fabricating a flexible electrode assembly, comprising: The outer peripheral surface of the negative current collector is coated with a negative electrode active material coating, and the outer peripheral surface of the positive current collector is coated with a positive electrode active material coating. The coating of the negative electrode active material at at least one end of a negative electrode is scraped off to form a first exposed area, and the negative electrode is used as the winding center line. The negative electrode tab is electrically connected to the first exposed area by winding it around; A diaphragm is wound around the outer peripheral surface of the negative electrode; Using the winding center line as the winding axis, the positive electrode is wound in a spiral manner, and the coating of the positive electrode active material at at least one end of the positive electrode is scraped off to form a second exposed area. The positive electrode tab is electrically connected to the second exposed area in a wound manner; A diaphragm is wound around the outer peripheral surface of the positive electrode.

[0032] The lengths of the first and second exposed areas can be designed according to the number of turns of the tab.

[0033] The number of positive electrodes in the same layer can be one or more, and the number of negative electrodes other than the center can be one or more, or even zero.

[0034] Multiple layers of electrodes and multiple layers of separators can be formed radially from the inside out along the winding center line. The specific arrangement is: negative electrode, separator, positive electrode, separator, negative electrode, separator, positive electrode, separator... The negative electrode, separator, and positive electrode are spirally wound around the winding center line according to this arrangement. The number of negative electrodes and positive electrodes can be designed according to the battery capacity.

[0035] The first exposed area refers to the outer peripheral surface (conductive area) of the negative current collector exposed at the end of the negative electrode.

[0036] The second exposed area refers to the outer peripheral surface (conductive area) of the positive current collector exposed at the end of the positive electrode.

[0037] This application shortens the ion transport path by using a negative electrode as the winding center line and winding the positive electrode in a spiral manner, while simultaneously winding a diaphragm between adjacent positive and negative electrodes. The adaptive nature of the spiral structure also improves the overall bending and torsion performance. Furthermore, the negative electrode tab is electrically connected to the first exposed area by winding before the diaphragm is wound, and the positive electrode tab is electrically connected to the second exposed area by winding before the diaphragm is wound. This method embeds the electrode tab transfer process within the winding process, enabling both the electrode assembly and the diaphragm formed after winding to exert radial constraint forces on the electrode tab connection position. This improves the reliability of the electrode tab electrical connection, reduces the possibility of loosening, and enhances overall connection reliability.

[0038] In some embodiments, both the positive and negative electrodes can be made of metal wire with a diameter of 0.1mm-0.5mm. The positive electrode can be made of the same material as the positive current collector, and the negative electrode can be made of the same material as the negative current collector. The positive current collector includes, but is not limited to, aluminum wire or a composite conductive wire formed by combining aluminum and polymer materials, such as a metallized polymer composite wire with a core layer of polymer materials such as polyethylene terephthalate (PET), polypropylene (PP), or polyimide (PI) and an aluminum or aluminum alloy conductive layer on its outer peripheral surface. The positive electrode can be made of aluminum or aluminum alloy. The negative current collector includes, but is not limited to, copper wire, copper alloy, nickel-plated copper, or a composite conductive wire formed by combining copper and polymer materials, such as a metallized polymer composite wire with a core layer of polymer materials such as PET, PP, or PI and a copper or copper alloy conductive layer on its outer peripheral surface. The negative electrode can be made of, but is not limited to, any one of copper wire, copper alloy, or nickel-plated copper.

[0039] In some embodiments, the membrane material includes, but is not limited to, polyethylene (PE), polypropylene (PP), PE / PP composite microporous membrane, polyimide (PI), polyvinylidene fluoride (PVDF), or copolymers thereof (such as PVDF). HFP), polyethylene terephthalate (PET) nonwoven fabric or microporous membrane, polyamide (PA) nonwoven fabric, and modified porous membranes with inorganic ceramic particles such as alumina, silica or titanium dioxide on the surface.

[0040] In some embodiments, the length of both the positive and negative tabs exposed on the electrode assembly can be set to, but is not limited to, 5mm-10mm.

[0041] In some embodiments, the cross-sections of both the positive current collector and the negative current collector can be either flat or circular.

[0042] In some embodiments, the diameter of the negative current collector can range from 0.1 mm to 0.5 mm, and the thickness of the negative electrode active material coating can range from 0.05 mm to 0.2 mm.

[0043] In some embodiments, electrically connecting the negative electrode tab to the first exposed area in a wound manner includes: The negative electrode tab is electrically connected to the first exposed area in a spiral winding manner; And / or, electrically connecting the positive electrode tab to the second exposed area in a helical winding manner, including: The positive electrode tab is electrically connected to the second exposed area in a spiral winding manner.

[0044] The spiral winding method can increase the contact area, making the tabs less likely to loosen and increasing the firmness. In the above-mentioned embodiment where the diaphragm covering the positive electrode includes the corresponding tabs and the second exposed area, the diaphragm can form a restraining force on the wound tabs, further increasing the firmness and playing an insulating role. On the other hand, it can increase the current flow area at the tab connection position.

[0045] In some embodiments, the number of negative electrodes is one, and the number of positive electrodes is multiple. Using a winding center line as the winding axis, the positive electrodes are wound in a spiral manner. The positive electrode active material coating at at least one end of the positive electrode is scraped off to form a second exposed area, including: Using the winding center line as the winding axis, multiple positive electrodes are spirally wound in parallel. The coating of the positive electrode active material at the same end of each positive electrode is scraped off to form a second exposed area.

[0046] Multiple positive electrodes spirally wound in parallel means: aligning multiple positive electrodes side by side without twisting them together, and then spirally winding them together along the center line of the winding.

[0047] This application employs multiple positive electrode wires spirally wound around a single negative electrode wire. Compared to a single positive electrode and a single negative electrode, the ion transport interface between the positive and negative electrode wires is increased, reducing the ion transport obstruction problem caused by the traditional solution of increasing capacity by thickening the electrode coating. Furthermore, the electrode active material can fully participate in the electrochemical reaction, improving the rate performance and cycle stability of the battery cell.

[0048] In some embodiments, both the number of negative electrodes and the number of positive electrodes are multiple; after winding a diaphragm around the outer peripheral surface of the positive electrode, the method for fabricating the flexible electrode assembly further includes: Using the winding center line as the winding axis, first wind one layer of negative electrode in a spiral manner, and then wind the remaining negative electrodes and the remaining positive electrodes in an alternating spiral manner to form multiple layers of negative electrodes and multiple layers of positive electrodes arranged radially staggered along the winding center line, and a diaphragm is wound between adjacent layers of negative electrodes and layers of positive electrodes. After each layer of negative electrode is wound, the coating of the negative active material at at least one end of the negative electrode layer is scraped off to form a first exposed area. The negative electrode tab is electrically connected to the first exposed area by winding, and then the separator is wound. After each layer of positive electrode is wound, the coating of the positive active material at at least one end of the positive electrode layer is scraped off to form a second exposed area. The positive electrode tab is electrically connected to the second exposed area by winding, and then the separator is wound.

[0049] The remaining negative and positive electrodes are spirally wound in an alternating manner, meaning that multiple layers of electrodes can be formed along the radial direction from the center line outwards. The specific arrangement is: one layer of negative electrode, one layer of positive electrode, one layer of negative electrode, one layer of positive electrode, and so on. The remaining negative and positive electrodes can be zero layers, one layer, or two or more layers.

[0050] The number of positive electrodes in each layer can be one or more, and the number of negative electrodes in each layer, excluding the winding center line, can also be one or more.

[0051] The structure of this embodiment has the following technical effects: First, by completing the preparation of the first exposed area of ​​the central negative electrode and the winding of the negative electrode tab in advance, the problem of limited internal space and restricted operation of the electrode assembly after multi-layer winding in the current transfer process is solved, which can reduce defects such as electrode tab misalignment, poor contact, and loose connection. Second, the helical winding structure of the multi-layer positive and negative electrodes not only retains the excellent bending and torsional self-adaptive performance of the helical structure, but also increases the battery energy storage capacity by increasing the number of negative electrodes, thereby improving the capacity of the fiber battery. Third, the multi-layer helical structure of the formed electrode assembly can form a uniform radial wrapping constraint force on the connection positions of the internal positive and negative electrode tabs, achieving stable electrical connection without relying on welding, effectively reducing the risk of electrode tab breakage, delamination, and electrical connection failure.

[0052] In some embodiments, each layer contains multiple negative electrodes, and the remaining negative and positive electrodes are spirally wound in an alternating manner with the winding center line as the winding axis, including: spirally winding multiple negative electrodes in the same layer in parallel with the winding center line as the winding axis; and / or Each layer contains multiple positive electrodes. The remaining negative and positive electrodes are spirally wound in an alternating manner, with the winding center line as the winding axis. This includes spirally winding multiple positive electrodes in the same layer in parallel, with the winding center line as the winding axis.

[0053] Using the winding center line as the winding axis, multiple negative electrodes in the same layer are spirally wound in parallel: multiple negative electrodes are aligned side by side without being twisted together, and then spirally wound together along the winding center line.

[0054] The technical effect of this embodiment of the application is that by setting multiple negative electrodes in each layer and / or multiple positive electrodes in each layer, the overall capacity of the battery cell can be increased.

[0055] In some embodiments, a diaphragm is wound around the outer peripheral surface of the negative electrode, including: The diaphragm is configured to cover the first exposed area of ​​the corresponding negative electrode; And / or, a diaphragm is wound around the outer peripheral surface of the positive electrode, comprising: The diaphragm is configured to cover the second exposed area of ​​the corresponding positive electrode.

[0056] Through the above process, the diaphragm can cover the corresponding negative tab and the first exposed area, thus constraining the negative tab and the first exposed area. The diaphragm can also cover the corresponding positive tab and the second exposed area, thus constraining the positive tab and the second exposed area, thereby improving the reliability of the tab connection. At the same time, it can reduce the possibility of short circuit caused by the connection between the positive and negative tabs.

[0057] In some embodiments, the diaphragm corresponding to the negative electrode may not cover the corresponding negative tab and the first exposed area. After the negative tab is electrically connected to the first exposed area in a wound manner, the outer surface of the first exposed area is wrapped with an insulating layer, which surrounds the first exposed area and wraps the portion of the negative tab located in the first exposed area, such as an insulating adhesive layer. Similarly, the diaphragm corresponding to the positive electrode may not cover the corresponding positive tab and the second exposed area. After the positive tab is electrically connected to the second exposed area in a wound manner, the outer surface of the second exposed area is wrapped with an insulating layer, which surrounds the second exposed area and wraps the portion of the positive tab located in the second exposed area. Alternatively, the first exposed area can be wrapped with an insulating layer as described above, then the negative electrode can be wrapped with the corresponding diaphragm to cover the first exposed area, and the second exposed area can be wrapped with an insulating layer as described above, then the positive electrode can be wrapped with the corresponding diaphragm to cover the second exposed area, thereby improving the insulation performance between adjacent positive and negative tabs.

[0058] In some embodiments, the method for fabricating a flexible electrode assembly further includes: After all the positive and negative electrodes are wound, at least one layer of diaphragm is spirally wound around the center line of the winding, so that the diaphragm is located on the outermost layer of all the positive and negative electrodes. The tail end of the outermost diaphragm is fixed with insulating tape.

[0059] Therefore, the tail end of the diaphragm is fixed with insulating tape to prevent the electrode assembly from becoming loose.

[0060] In some embodiments, before electrically connecting the negative electrode tab to the first exposed area, the method for fabricating the flexible electrode assembly further includes: The surface of the first exposed area is cleaned to remove impurities and oxide layers. And / or, before electrically connecting the positive electrode tab to the second exposed area, the preparation method further includes: The surface of the second exposed area is cleaned to remove impurities and oxide layers.

[0061] The first and second exposed areas are cleaned to remove oxide layers and impurities. Cleaning methods include ultrasonic cleaning, plasma treatment, and mechanical wiping, with a processing time of 30-120 seconds.

[0062] After cleaning, follow the above methods and steps to wrap the positive electrode tab around the second exposed area and the negative electrode tab around the first exposed area.

[0063] This improves the reliability of the electrical connection between the positive electrode tab and the second exposed area, as well as between the negative electrode tab and the first exposed area.

[0064] In some embodiments, the length of the first exposed area (the dimension along the length direction of the negative current collector) ranges from 5 mm to 15 mm; and / or, the length of the second exposed area (the dimension along the length direction of the positive current collector) ranges from 5 mm to 15 mm.

[0065] As an example, the number of turns for both the positive and negative electrodes should not be less than 5.

[0066] Therefore, if the size of the exposed area (first exposed area or second exposed area) is too large (exceeding 15mm), it will affect the battery capacity. Conversely, if the size of the exposed area is too small (less than 5mm), the number of turns of the tab will be too few, making it easy for the tab to misalign or detach from the end of the corresponding current collector (positive or negative current collector) after winding, affecting the reliability of the connection. Therefore, considering both the battery capacity and the connection reliability of the tab, the length of the first exposed area and / or the length of the second exposed area are set to a range of 5mm to 15mm.

[0067] In some embodiments, in any two adjacent layers of positive and negative electrodes, the electrode located in the inner layer is the first electrode, and the electrode located in the outer layer of the first electrode is the second electrode. During the winding process, the tension of the second electrode is controlled to be less than that of the first electrode.

[0068] This prevents excessive internal stress in the electrode assembly from causing the positive or negative electrode to puncture the diaphragm and trigger a short circuit.

[0069] In some embodiments, the positive current collector is a strip or wire structure. The remaining negative current collectors, except those wound around the center line, are all wire or strip structures. This allows the fabricated electrode assembly to have a certain degree of flexibility, enabling bending and allowing the fabricated battery cell to adapt to various morphological changes, while also possessing functions such as weaving.

[0070] In a specific example of a method for fabricating a flexible electrode assembly, there are M negative collector streamlines and N positive collector streamlines, where M and N are both integers greater than or equal to 1. Figure 1 As shown, it includes the following steps: S100. Coat the outer periphery of M negative current collectors with a negative electrode active material coating to form M negative electrodes, and coat the outer periphery of N positive current collectors with a positive electrode active material coating to form N positive electrodes, where M and N are both integers greater than or equal to 1. S200. First, scrape off the coating of the negative electrode active material at both ends of a negative electrode to form the first exposed area. S300: Clean the surface of the first exposed area to remove the oxide layer and impurities. S400, the negative electrode tab is spirally wound around the first exposed area to make the electrode tab electrically connected to the negative current collector; S500, wind the diaphragm, ensuring that the diaphragm at least covers the negative electrode active material coating and the area where the negative electrode tab is wound; S600: Using a negative electrode as the winding center line, a layer of positive electrode is spirally wound; S700, scrape off the positive electrode active material coating at least one end of the positive electrode to form a second exposed area; S800: Clean the surface of the second exposed area to remove the oxide layer and impurities. S900, the positive electrode tab is spirally wound around the second exposed area to make the positive electrode tab electrically connected to the positive current collector; S1000, Wrap the diaphragm so that the diaphragm at least covers the positive electrode active material coating and the area where the positive electrode tab is wrapped; S1100. If M=1, then stop winding and fix the outermost diaphragm with insulating tape at the end. S1200 If M is greater than 1, continue to spirally wind one layer of negative electrode, repeat steps S200-S1000 until the preset number of layers is reached, and fix the outermost diaphragm with insulating tape.

[0071] The manufacturing method of this application is not limited to the above steps. For example, the coating of the positive current collector and the negative current collector of S100 can be carried out simultaneously, or it can be set before the winding step according to the winding sequence.

[0072] The following description uses battery cells from some embodiments of this application as examples.

[0073] One type of battery cell in this application, such as Figure 2 and Figure 3 As shown, it includes an encapsulation layer 200 and an electrode assembly 100. The encapsulation layer 200 has a receiving cavity. The electrode assembly 100 is prepared using the flexible electrode assembly preparation method described in the above embodiments, and the electrode assembly 100 is located within the receiving cavity.

[0074] The encapsulation layer 200 contains an electrolyte in its cavity. The outer side of the encapsulation layer 200 is provided with a positive electrode terminal and a negative electrode terminal. The positive electrode tab is electrically connected to the positive electrode terminal, and the negative electrode tab is electrically connected to the negative electrode terminal.

[0075] The encapsulation layer 200 can be selected from, but is not limited to, fluorinated ethylene propylene copolymer (FEP), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyimide (PI), polyvinyl chloride (PVC), or thermoplastic polyurethane (TPU); preferably fluorinated ethylene propylene copolymer (FEP) or polypropylene (PP), because it has excellent resistance to electrolyte corrosion, low heat shrinkage rate and high light transmittance / visibility, which are suitable for the encapsulation requirements of flexible fibrous lithium-ion batteries.

[0076] In some embodiments, the electrode assembly 100 includes a positive electrode 10 and a negative electrode 20, wherein the positive electrode 10 is spirally wound around the negative electrode 20 on the outer peripheral surface of the negative electrode 20.

[0077] In some embodiments, the positive electrode 10 has multiple electrodes and a single layer, with the multiple positive electrodes 10 spirally coiled around the outer peripheral surface of the same negative electrode 20. On a cross-section perpendicular to the negative electrode 20, the multiple positive electrodes 10 are arranged circumferentially along the negative electrode 20. For example, the number of positive electrodes 10 is 2-6.

[0078] In some embodiments, both the number of negative electrodes 20 and the number of positive electrodes 10 are multiple. Each of the multiple positive electrodes 10 has a first helical structure, and one negative electrode 20 is not wound around and is located at the center of the helical structure; that is, the axis of the negative electrode 20 is the axis of the first helical structure. The remaining negative electrodes 20 also have a second helical structure centered on this negative electrode 20. Along the radial direction of the electrode assembly 100, the negative electrodes 20 and positive electrodes 10 are adjacent and separated by a membrane 30. Here, "adjacent" means that, along the radial direction of the electrode assembly 100, the closest layer of negative electrodes 20 and the closest layer of positive electrodes 10 are not wound with other negative electrodes 20 and positive electrodes 10 except for the membrane 30. Both the positive electrodes 10 and the negative electrodes 20 have multiple layers.

[0079] The following description uses battery devices from some embodiments of this application as examples.

[0080] A battery device according to this application includes at least one battery cell as described in the above embodiments.

[0081] The number of battery cells can be multiple, and multiple battery cells can be connected in series and / or parallel to form a battery device. The battery device can be, but is not limited to, a braided structure. For example, watch straps, bracelets, or clothing, etc. In other words, the battery device can not only act as a battery to power electrical devices, but also serve as a wearable device.

[0082] The following description uses electrical equipment from some embodiments of this application as examples.

[0083] An electrical device according to this application includes the battery device described in the above embodiments, the battery device being used to provide electrical energy to the electrical device.

[0084] The electrical equipment can be, but is not limited to, smart wearable devices, such as smart watch straps, smart bracelets, and smart clothing (heated clothing, heart rate monitoring clothing); flexible portable electronic products, such as power supplies for flexible displays, foldable electronic tags, and flexible sensor nodes; and medical and implantable flexible devices, such as flexible physiological signal monitoring patches and power supply units for wearable drug delivery systems.

[0085] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a flexible electrode assembly, characterized in that, include: A negative electrode is formed by coating the outer peripheral surface of the negative current collector with a negative active material coating, and a positive electrode is formed by coating the outer peripheral surface of the positive current collector with a positive active material coating. The coating of the negative electrode active material at at least one end of the negative electrode is scraped off to form a first exposed area, and the negative electrode is used as the winding center line. The negative electrode tab is electrically connected to the first exposed area by wrapping it around the electrode. A diaphragm is wound around the outer peripheral surface of the negative electrode; Using the winding center line as the winding axis, the positive electrode is wound in a spiral manner, and the positive electrode active material coating at at least one end of the positive electrode is scraped off to form a second exposed area; The positive electrode tab is electrically connected to the second exposed area in a wound manner; A diaphragm is wound around the outer peripheral surface of the positive electrode.

2. The method for fabricating a flexible electrode assembly according to claim 1, characterized in that, The step of electrically connecting the negative electrode tab to the first exposed area in a wound manner includes: The negative electrode tab is electrically connected to the first exposed area in a spiral winding manner; And / or, the method of electrically connecting the positive electrode tab to the second exposed area in a wound manner includes: The positive electrode tab is electrically connected to the second exposed area in a spiral winding manner.

3. The method for fabricating a flexible electrode assembly according to claim 1, characterized in that, The number of negative electrodes is one, and the number of positive electrodes is multiple. The positive electrodes are wound in a spiral manner with the winding center line as the winding axis, and the positive electrode active material coating at at least one end of the positive electrode is scraped off to form a second exposed area, including: Using the winding center line as the winding axis, multiple positive electrodes are spirally wound in parallel, and the coating of the positive electrode active material at the same end of each positive electrode is scraped off to form the second exposed area.

4. The method for fabricating a flexible electrode assembly according to claim 1, characterized in that, The number of negative electrodes and the number of positive electrodes are both multiple; after a diaphragm is wound around the outer peripheral surface of the positive electrode, the method for fabricating the flexible electrode assembly further includes: Using the winding center line as the winding axis, first wind one layer of negative electrode in a spiral manner, and then wind the remaining negative electrodes and the remaining positive electrodes in an alternating spiral manner to form multiple layers of negative electrodes and multiple layers of positive electrodes arranged radially staggered along the winding center line, and a diaphragm is wound between adjacent layers of negative electrodes and layers of positive electrodes. After each layer of the negative electrode is wound, the coating of the negative active material at at least one end of the negative electrode layer is scraped off to form the first exposed area. The negative electrode tab is electrically connected to the first exposed area by winding, and then the separator is wound. After each layer of the positive electrode is wound, the coating of the positive active material at at least one end of the positive electrode layer is scraped off to form the second exposed area. The positive electrode tab is electrically connected to the second exposed area by winding, and then the separator is wound.

5. The method for fabricating a flexible electrode assembly according to claim 4, characterized in that, Each layer contains multiple negative electrodes. Using the winding center line as the winding axis, the remaining negative and positive electrodes are spirally wound in an alternating manner, including: using the winding center line as the winding axis, multiple negative electrodes in the same layer are spirally wound in parallel; and / or The number of positive electrodes in each layer is multiple. With the winding center line as the winding axis, the remaining negative electrodes and the remaining positive electrodes are spirally wound in an alternating manner, including: with the winding center line as the winding axis, multiple positive electrodes in the same layer are spirally wound in parallel.

6. The method for fabricating a flexible electrode assembly according to claim 4, characterized in that, All negative current collectors other than the winding center line are of wire or strip structure.

7. The method for preparing a flexible electrode assembly according to any one of claims 3-6, characterized in that, The method for preparing the flexible electrode assembly further includes: After all the positive electrodes and all the negative electrodes are wound, at least one layer of diaphragm is spirally wound around the winding center line, so that the diaphragm is located on the outermost layer of all the positive electrodes and all the negative electrodes, and the tail end of the outermost diaphragm is fixed with insulating tape.

8. The method for fabricating a flexible electrode assembly according to any one of claims 1-6, characterized in that, The step of winding a diaphragm on the outer peripheral surface of the negative electrode includes: The diaphragm is configured to cover the first exposed area of ​​the corresponding negative electrode; And / or, the diaphragm wound around the outer peripheral surface of the positive electrode includes: The diaphragm is configured to cover the second exposed area of ​​the corresponding positive electrode.

9. The method for fabricating a flexible electrode assembly according to any one of claims 1-6, characterized in that, Before electrically connecting the negative electrode tab to the first exposed area, the method for preparing the flexible electrode assembly further includes: The surface of the first exposed area is cleaned to remove impurities and oxide layers. And / or, before electrically connecting the positive electrode tab to the second exposed area, the preparation method further includes: The surface of the second exposed area is cleaned to remove impurities and oxide layers.

10. The method for fabricating a flexible electrode assembly according to any one of claims 1-6, characterized in that, The length of the first exposed area ranges from 5mm to 15mm; and / or, the length of the second exposed area ranges from 5mm to 15mm; And / or, in any two adjacent layers of the positive electrode and the negative electrode, the electrode located in the inner layer is the first electrode, and the electrode located in the outer layer of the first electrode is the second electrode. During the winding process, the tension of the second electrode is controlled to be less than the tension of the first electrode.

11. The method for fabricating a flexible electrode assembly according to any one of claims 1-6, characterized in that, The positive current collector has a strip-like structure or a filament structure.

12. A single battery cell, characterized in that, include: Encapsulation layer with a receiving cavity; The electrode assembly is prepared by the flexible electrode assembly preparation method according to any one of claims 1-11, and the electrode assembly is located within the receiving cavity.

13. A battery device, characterized in that, It includes at least one battery cell as described in claim 12.

14. An electrical appliance, characterized in that, Includes the battery device as described in claim 13, the battery device being used to provide electrical energy to the electrical equipment.

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