Battery cell, battery device, and electric device

Abstract

The application discloses a battery monomer, a battery device and an electric equipment. The battery monomer comprises an electrode assembly, the electrode assembly comprises a first diaphragm, N positive electrode filaments and N negative electrode filaments, N is an integer greater than or equal to 2, the outer peripheral surface of at least one of the positive electrode filaments and the negative electrode filaments is wrapped with the first diaphragm, the first diaphragm insulates the positive electrode filaments and the negative electrode filaments, the N positive electrode filaments and the N negative electrode filaments are spirally wound around a first axis to form an electrode beam, the N positive electrode filaments and the N negative electrode filaments are arranged in a staggered mode along the circumference of the first axis, and one negative electrode filament is arranged between two adjacent positive electrode filaments.

Description

Technical Field

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

[0002] Currently, fiber lithium-ion batteries mainly come in two forms: one is a two-strand fiber lithium-ion battery structure obtained by twisting positive and negative electrode fibers together, and the other is a coaxial fiber lithium-ion battery structure with a central axis, in which positive and negative electrode wires are wound or wrapped around it. Traditional twisted-wire fiber lithium batteries use a two-strand structure with a single positive electrode wire and a single negative electrode wire. In addition, multiple positive electrode wires form a positive electrode wire cluster, and multiple negative electrode wires form a negative electrode wire cluster, which are then twisted together to form the electrode body. The total amount of active material that this electrode body can hold is limited, and the overall weight ratio of active material is low, ultimately resulting in a low battery energy density, which cannot meet the requirements for long-range use. Furthermore, there is a problem with poor rate performance. Specifically, in the two-strand structure, the positive and negative electrode wires only form a linear contact interface, a single contact form, which significantly hinders the migration and conduction of lithium ions between the positive and negative electrodes, resulting in low lithium ion transport efficiency and insufficient high-current discharge capacity, leading to poor charge-discharge rate performance. Summary of the Invention

[0003] The main objective of this application is to provide a battery cell, a battery device, and an electrical device to solve the problem of poor charge and discharge rate performance of the electrodes in the prior art.

[0004] To achieve the above objectives, a first aspect of this application provides a battery cell comprising: The electrode assembly includes a first diaphragm, N positive electrode wires and N negative electrode wires, where N is an integer greater than or equal to 2. The outer peripheral surface of at least one of the positive electrode wires and the negative electrode wires is covered by the first diaphragm, which insulates the positive electrode wires and the negative electrode wires. The N positive electrode wires and the N negative electrode wires are spirally wound around a first axis to form an electrode bundle. Along the circumference of the first axis, the N positive electrode wires and the N negative electrode wires are staggered, and a negative electrode wire is provided between two adjacent positive electrode wires.

[0005] Traditional two-strand structures have only one linear contact interface, limiting lithium-ion transport efficiency. In this application, N positive electrode wires and N negative electrode wires are staggered, with a negative electrode wire between every two adjacent positive electrode wires. This results in multiple adjacent negative electrode wires surrounding each positive electrode wire, increasing the number of linear contact points within the electrode bundle, increasing the number of linear transport channels between the positive and negative electrodes, shortening the lithium-ion diffusion path, and reducing transport impedance, thereby improving the charge / discharge rate of the battery cell. Furthermore, with both N positive and N negative electrode wires being greater than or equal to 2, the total amount of active material per unit length of each positive and negative electrode wire remains unchanged, which increases the gravimetric energy density of the battery cell.

[0006] In some embodiments, a first diaphragm is wrapped around the outer peripheral surface of the negative electrode wire, and the first diaphragm abuts against two adjacent positive electrode wires circumferentially along the first axis.

[0007] In some embodiments, the outer peripheral diameter D1 of the first diaphragm and the outer peripheral diameter D2 of the positive electrode wire satisfy the relationship: 1≤D1 / D2≤1.1.

[0008] In some embodiments, the battery cell further includes an encapsulation layer having a receiving cavity in which the electrode assembly is located.

[0009] In some embodiments, the encapsulation layer is a flexible material layer.

[0010] In some embodiments, the pitch of both the positive and negative electrode wires ranges from 2 mm to 8 mm; and / or, the positive electrode wire includes a positive current collector, the diameter of which ranges from 0.1 mm to 0.5 mm; and / or, the negative electrode wire includes a negative current collector, the diameter of which ranges from 0.1 mm to 0.5 mm; and / or, the thickness of the first diaphragm ranges from 2 micrometers to 40 micrometers.

[0011] In some embodiments, there are multiple electrode bundles, which are arranged sequentially along the radial direction of the first axis, and in any two adjacent electrode bundles, one electrode bundle wraps around the outer peripheral surface of the other electrode bundle.

[0012] In some embodiments, the positive electrode wire includes a positive current collector and a positive active material layer. The outer peripheral surface of the positive current collector is covered with the positive active material layer. Along the circumferential direction of the positive current collector, the positive active material layer wraps around the outer peripheral surface of the positive current collector and extends along the length direction of the current collector. The mass of the positive active material layer ranges from 150 mg / m to 180 mg / m.

[0013] In some embodiments, the positive electrode active material layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent, wherein the mass percentage ratio of the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent is (80%–95%): (1%–10%): (1%–10%).

[0014] In some embodiments, the negative electrode wire includes a negative current collector and a negative active material layer. The outer peripheral surface of the negative current collector is covered with the negative active material layer. Along the circumferential direction of the negative current collector, the negative active material layer wraps around the outer peripheral surface of the negative current collector and extends along the length direction of the current collector. The mass of the negative active material layer ranges from 100 mg / m to 130 mg / m.

[0015] In some embodiments, the negative electrode active material layer includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent, and the mass percentage ratio of the three components is (80% to 95%): (1% to 10%): (1% to 10%).

[0016] In some embodiments, the negative electrode adhesive includes sodium carboxymethyl cellulose and styrene-butadiene rubber, wherein the mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber is 1:(1.5-3).

[0017] In some embodiments, the mass energy density of the battery cell is greater than or equal to 120Wh / kg.

[0018] A second aspect of this application provides a battery device comprising at least one battery cell as described in the first aspect, wherein when there are multiple battery cells, the multiple battery cells are electrically connected in series and / or in parallel.

[0019] A third aspect of this application provides an electrical device comprising the battery device described in the second aspect, the battery device being used to provide electrical energy to the electrical device. Attached Figure Description

[0020] 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 , Figure 3 and Figure 4 These are schematic cross-sectional views of a single battery cell through the positive electrode wire and the negative electrode wire, respectively, provided in different embodiments of this application. Figure 2 This application provides a schematic diagram of the structure of an electrode assembly in a battery cell, based on some embodiments. 100. Electrode assembly; 10. Positive electrode wire; 11. Positive electrode active material layer; 12. Positive current collector; 20. Negative electrode wire; 21. Negative electrode active material layer; 22. Negative current collector; 30. First separator; 200. Encapsulation layer. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] In existing fibrous lithium-ion battery cell technology, an electrode cluster structure is typically used, which integrates multiple positive electrode wires into a positive electrode cluster and multiple negative electrode wires into a negative electrode cluster, and then twists or coils the positive and negative electrode clusters together. In this structure, only one cluster exists between the positive and negative electrodes. right The contact interface of the clusters, and the filaments of the same polarity are always clustered together. Fibrous lithium-ion batteries are also formed by spirally winding a positive electrode filament and a negative electrode filament. Regardless of the structure used, there is only one line contact ion interface between a single positive electrode filament and a single negative electrode filament, which results in poor charge and discharge rate performance.

[0027] This application employs a structure with N≥2 and staggered arrangement, which allows a single positive electrode wire to form line contact with two negative electrode wires on both sides of the circumference, thereby doubling the number of ion transport interfaces at the physical level and solving the problem of poor charge and discharge rate performance of a single battery cell due to the influence of ion transport interfaces.

[0028] The reason why those skilled in the art have not proposed staggering the N positive electrode wires and N negative electrode wires (N≥2) and ensuring that a single positive electrode wire is in contact with two adjacent negative electrode wires simultaneously (i.e., only one negative electrode wire is placed between two adjacent positive electrode wires, with negative electrode wires on both sides of each positive electrode wire) is mainly due to the following technical biases and cognitive obstacles: Existing technologies tend to bundle wires of the same polarity into clusters to reduce manufacturing complexity, and it is believed that breaking the cluster structure and alternating positive and negative electrode wires will increase the risk of short circuits, especially when a single positive electrode wire is in contact with two negative electrode wires simultaneously. This application overcomes industry bias by setting the number of positive and negative electrode wires to be equal, and both greater than or equal to 2, and staggering the positive and negative electrode wires so that at least two ion transport interfaces are formed between the same positive electrode wire and two adjacent negative electrode wires, thereby doubling the number of ion transport interfaces to improve the charge and discharge rate performance of the fiber lithium-ion battery cell.

[0029] The following description, with reference to the accompanying drawings, uses some battery cells from embodiments of this application as examples.

[0030] Please refer to Figure 1 and Figure 2This application provides a battery cell including an electrode assembly 100. The electrode assembly 100 includes a first separator 30, N positive electrode wires 10, and N negative electrode wires 20, where N is an integer greater than or equal to 2. The outer peripheral surface of at least one of the positive electrode wires 10 and negative electrode wires 20 is covered by the first separator 30, which insulates the positive electrode wires 10 and negative electrode wires 20. The N positive electrode wires 10 and N negative electrode wires 20 are spirally wound around a first axis to form an electrode bundle. Along the circumferential direction of the first axis, the N positive electrode wires 10 and N negative electrode wires 20 are staggered, and a negative electrode wire 20 is provided between two adjacent positive electrode wires 10.

[0031] Each positive electrode wire 10 has a positive tab connected to its end, and each negative electrode wire 20 has a negative tab connected to its end. Positive tabs of the same polarity can be electrically connected to each other, and negative tabs of the same polarity can be electrically connected to each other. The positive and negative tabs are arranged alternately. The positive and negative tabs can be located at the same end of the electrode assembly 100 or at opposite ends.

[0032] The positive electrode wire 10 includes a positive current collector 12 and a positive active material layer 11 coated on the outer periphery of the positive current collector 12; the negative electrode wire 20 includes a negative current collector 22 and a negative active material layer 21 coated on the outer periphery of the negative current collector 22. The positive current collector 12 can be an 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 periphery. The negative current collector 22 can be a copper wire 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 periphery.

[0033] The first diaphragm 30 may be a lithium-ion permeable porous insulating film, the material of which 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). The first separator 30 is made of HFP (hydrophobic polymer), polyethylene terephthalate (PET) nonwoven fabric or microporous membrane, polyamide (PA) nonwoven fabric, and a modified porous first separator 30 with inorganic ceramic particles such as alumina, silica, or titanium dioxide coated on its surface. The first separator 30 is wrapped around the outer peripheral surface of the positive electrode wire 10 and / or the negative electrode wire 20 in a tubular or strip shape, so that the positive electrode wire 10 and the negative electrode wire 20 are mutually insulated, while allowing lithium ions to pass through freely.

[0034] The first diaphragm 30 is wrapped around the outer surface of the positive electrode wire 10 and / or the negative electrode wire 20 in a tubular, sleeve-like or longitudinally wrapped manner. When at least one of the positive electrode wire 10 and the negative electrode wire 20 is wrapped by the first diaphragm 30, the two are electrically insulated and isolated from each other by the first diaphragm 30 to prevent short circuit.

[0035] Traditional two-strand structures have only one linear contact interface, limiting lithium-ion transport efficiency. In this application, N positive electrode wires 10 and N negative electrode wires 20 are staggered, with a negative electrode wire 20 between every two adjacent positive electrode wires 10. This results in multiple adjacent negative electrode wires 20 distributed around each positive electrode wire 10, increasing the number of linear contact points within the electrode bundle, increasing the number of linear transport channels between the positive and negative electrodes, shortening the lithium-ion diffusion path, and reducing transport impedance, thereby improving the charge-discharge rate of the battery cell. Furthermore, both N positive electrode wires 10 and N negative electrode wires 20 are greater than or equal to 2. Under the premise that the mass of active material per unit length of each positive electrode wire 10 and each negative electrode wire 20 remains unchanged, the total amount of active material can be increased, which is beneficial to improving the mass energy density of the battery cell.

[0036] Please refer to Figure 2 As another optional implementation, N=2. When N=2, the electrode assembly 100 includes two positive electrode wires 10 and two negative electrode wires 20. Viewed along a cross-sectional direction perpendicular to the first axis, the two positive electrode wires 10 and the two negative electrode wires 20 are arranged alternately and staggeredly, forming a ring arrangement of "+, -, +, -" along the circumferential direction of the first axis (where "+" represents the cross-section of the positive electrode wire 10 and "-" represents the cross-section of the negative electrode wire 20). In this case, a negative electrode wire 20 is provided between any two adjacent positive electrode wires 10, and each positive electrode wire 10 has negative electrode wires 20 on both sides along the circumferential direction, and each negative electrode wire 20 has positive electrode wires 10 on both sides along the circumferential direction. In this structure, the same positive electrode wire 10 simultaneously forms two linear ion transport interfaces with the two negative electrode wires 20, which significantly increases the number of ion transport channels between the positive and negative electrodes compared to the traditional single twisted pair structure, which is beneficial to further improve the rate performance of the battery cell.

[0037] As another alternative implementation method, please refer to Figure 3 With N=3, the electrode assembly 100 includes three positive electrode wires 10 and three negative electrode wires 20. Viewed along a cross-sectional direction perpendicular to the first axis, the three positive electrode wires 10 and three negative electrode wires 20 are arranged in an alternating staggered pattern, forming a ring-shaped arrangement of "+, -, +, -, +, -". At this time, each positive electrode wire 10 is also held by two negative electrode wires 20, creating six line contact points within the electrode bundle, which is beneficial for further improving the rate performance of the battery cell.

[0038] As another alternative implementation method, please refer to Figure 4N=4, and the electrode assembly 100 includes 4 positive electrode wires 10 and 4 negative electrode wires 20. When viewed along a cross-sectional direction perpendicular to the first axis, the 4 positive electrode wires 10 and 4 negative electrode wires 20 are arranged alternately and staggeredly to form a ring arrangement structure of "+, -, +, -, +, -, +, -, +, -".

[0039] In some embodiments, the first diaphragm 30 is wrapped around the outer peripheral surface of the negative electrode wire 20, and the first diaphragm 30 abuts against two adjacent positive electrode wires 10 in the circumferential direction along the first axis.

[0040] In lithium-ion battery design, under the same loading of active materials, the required cross-sectional area of ​​the negative electrode wire 20 is usually smaller than that of the positive electrode wire 10, resulting in the diameter of the bare negative electrode wire 20 being thinner than that of the positive electrode wire 10.

[0041] This application utilizes the thickness of the first separator 30 as an adjustment layer by wrapping the outer peripheral surface of the negative electrode wire 20 with the first separator 30. Since the first separator 30 covers the outer side of the thinner negative electrode wire 20, the overall outer diameter of the wrapped negative electrode wire 20 and the first separator 30 can be basically equal to the outer diameter of the unwrapped positive electrode wire 10.

[0042] When N positive electrode wires 10 and N negative electrode wires 20 are spirally wound to form an electrode bundle, the wires of equal diameter can form a more regular and compact circular or regular polygonal cross-section, reducing local gaps or stress concentrations caused by the uneven wire thickness, improving the structural compactness of the electrode bundle, and ensuring full contact between the first separator 30 and the positive electrode wire 10 to shorten the lithium-ion migration path, which is beneficial to improving the conductivity of the battery cell and thus improving the charge-discharge rate. On the other hand, the equal diameter structure makes the bending stress on each wire more uniform, preventing the thinner negative electrode wire 20 from breaking due to excessive stress, and also avoiding excessive compression and damage to the outer first separator 30 by the thicker positive electrode wire 10, thereby improving the mechanical durability and flexibility of the fiber battery.

[0043] In some embodiments, the outer peripheral diameter D1 of the first diaphragm 30 and the outer peripheral diameter D2 of the positive electrode wire 10 satisfy the relationship: 1≤D1 / D2≤1.1.

[0044] By using the first diaphragm 30 as an adjustment layer, the outer diameter of the thinner negative electrode wire 20 is made up to be basically equal to that of the positive electrode wire 10. This equal diameter design eliminates the stress concentration in the cross section caused by the different thickness of the wires, so that when N positive electrode wires 10 and N negative electrode wires 20 are spirally wound to form an electrode bundle, they can form a more regular and compact circular or regular polygonal cross section, which significantly improves the structural compactness of the electrode bundle.

[0045] In some embodiments, the battery cell further includes an encapsulation layer 200 having a receiving cavity, within which the electrode assembly 100 is located.

[0046] The encapsulation layer 200 serves to protect the electrode assembly 100 and is used to hold the electrolyte.

[0047] The encapsulation layer 200 can be made of rigid or flexible materials.

[0048] The encapsulation layer 200 is used to provide mechanical protection for the electrode assembly 100, isolate it from external moisture and oxygen, and maintain the morphological stability of the electrode bundle.

[0049] The encapsulation layer 200 effectively blocks external water vapor, oxygen, and contaminants from entering the containment cavity, preventing the positive electrode wire 10, negative electrode wire 20, and first separator 30 from degradation or side reactions caused by environmental factors. Especially when using low moisture permeability and electrolyte corrosion resistant materials such as FEP or PP, it can significantly extend the service life of the fiber battery. The encapsulation layer 200 also covers and constrains the electrode bundle, preventing the spirally wound N positive electrode wires 10 and N negative electrode wires 20 from loosening.

[0050] In some embodiments, the encapsulation layer 200 is a flexible material layer.

[0051] The encapsulation layer 200 can be made of one or more polymeric materials with good flexibility, heat-sealing properties, and barrier properties. The material 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). Fluorinated ethylene propylene copolymer (FEP) or polypropylene (PP) is preferred because it combines excellent resistance to electrolyte corrosion, low heat shrinkage, and high light transmittance / visibility, making it suitable for the encapsulation requirements of flexible fibrous lithium-ion batteries. The encapsulation layer 200 can be in the form of a tubular heat-shrink sleeve, a longitudinally folded heat-sealing film, or a coaxial extruded coating layer, and is tightly wrapped around the outer periphery of the electrode bundle after heating or hot pressing.

[0052] Therefore, battery cells can be pre-bent or woven into various preset shapes (such as S-shape, spiral, ring or wave shape) according to actual application needs, so that the battery cells can be used as batteries to power electrical devices in the form of woven fabric, such as watch straps, so that electrical devices do not need to reserve extra space for batteries, and the battery cells can be used for both wearing and power supply functions.

[0053] In some embodiments, the pitch of both the positive electrode wire 10 and the negative electrode wire 20 ranges from 2mm to 8mm.

[0054] As an example, the pitch of the positive electrode wire 10 and the negative electrode wire 20 are equal.

[0055] If the pitch of the positive electrode wire 10 and the negative electrode wire 20 is too small, the stress generated by their spiral winding will be too large, which will easily cause the active material on the coating surface to fall off. If the pitch is too large, the wires will not be wound tightly, resulting in insufficient contact between the positive and negative electrode wires, which will have an adverse effect on the performance of the battery cell. Therefore, the pitch of the positive electrode wire 10 and the negative electrode wire 20 is set to a range of 2mm to 8mm.

[0056] In some embodiments, the positive electrode wire 10 includes a positive current collector 12, the diameter of which ranges from 0.1 mm to 0.5 mm; and / or, the negative electrode wire 20 includes a negative current collector 22, the diameter of which ranges from 0.1 mm to 0.5 mm.

[0057] This allows for the production of thinner diameters for the positive electrode wire 10 and the negative electrode wire 20, thereby reducing the overall diameter of the battery cell. This facilitates the production of various shapes for the battery cell through weaving and other methods, making it easier to wear and supply power, and thus improving the applicability of the battery cell in different scenarios.

[0058] In some embodiments, the thickness of the first diaphragm 30 ranges from 2 micrometers to 40 micrometers.

[0059] If the first separator 30 is too thin, it will deform during the winding process and be easily punctured; if the first separator 30 is too thick, the ineffective mass will increase, which will lead to a decrease in the energy density of the battery cell. Therefore, the thickness of the first separator 30 is set to 2 micrometers to 40 micrometers.

[0060] In some embodiments, there are multiple electrode bundles, which are arranged sequentially along the radial direction of the first axis, and in any two adjacent electrode bundles, one electrode bundle wraps around the outer peripheral surface of the other electrode bundle.

[0061] The number of positive electrode wires 10 and negative electrode wires 20 in each electrode bundle is equal, and the number of positive electrode wires 10 between two adjacent electrode bundles can be unequal, as can the number of negative electrode wires 20.

[0062] This application utilizes radially nested multiple electrode bundles, enabling the total active material load per unit length to increase exponentially with the number of nesting layers while maintaining the flexibility of the battery cell. Since the newly added electrode bundles primarily increase the mass of the active material, the gravimetric and volumetric energy densities of the battery cell can be effectively improved.

[0063] Multiple electrode bundles can be connected in parallel through shared current collectors or end interconnection; that is, current collectors with the same polarity are electrically connected, while current collectors with opposite polarities are not connected. This increases the cross-sectional area of ​​the current output channel, which helps reduce the overall ohmic internal resistance of the battery cell. With low internal resistance, the heat generated by the battery during high-current charging and discharging is reduced, and temperature rise is effectively suppressed, further ensuring safety and cycle stability under high-rate conditions. Furthermore, when the battery cell bends, the outer electrode bundle bears tensile stress, while the inner electrode bundle bears compressive stress. Since each electrode bundle is composed of spirally wound positive electrode wire 10 and negative electrode wire 20, it has a certain degree of deformation self-adaptability. During the bending process of the battery cell, the bending stress is released through small relative slippage between layers, reducing the possibility of a single electrode bundle breaking due to excessive bending, and helping to improve the structural integrity and reliability of the battery cell during repeated bending.

[0064] In some embodiments, a second diaphragm is provided between two adjacent electrode bundles.

[0065] When the multi-layered nested electrode bundles are bent or twisted, there is a relative movement tendency between the inner and outer spiral wires. A second separator is provided between two adjacent electrode bundles as a flexible dielectric layer, which can reduce the friction between the inner and outer electrode bundles. This reduces the possibility of short circuits caused by the wear of the positive electrode wire 10 and negative electrode wire 20 between adjacent electrode bundles, which could lead to damage to the first separator 30 within the electrode bundle. This helps to improve the safety of the battery cell.

[0066] In some embodiments, the positive electrode wire 10 includes a positive current collector 12 and a positive active material layer. The outer peripheral surface of the positive current collector 12 is covered with the positive active material layer. Along the circumferential direction of the positive current collector 12, the positive active material layer wraps around the outer peripheral surface of the positive current collector 12 and extends along the length direction of the current collector. The mass of the positive active material layer ranges from 150 mg / m to 180 mg / m.

[0067] Since the positive electrode wire 10 lacks planar support compared to the electrode sheet, if the content of the positive active material layer is too low (<150 mg / m), although the bonding force is good, the total amount of active material per unit length is insufficient, which can easily lead to a low capacity of the battery cell. If the content of the positive active material layer is too high (>180 mg / m), the internal stress generated during the drying and shrinkage process after the slurry is coated on the positive electrode wire 10 exceeds the interfacial adhesion force between it and the current collector, which can easily lead to cracking, peeling, or powder shedding of the active material layer, affecting the cycle life and safety of the battery. Therefore, controlling the load at 150 mg / m to 180 mg / m can ensure a higher load level while ensuring a firm bond between the positive active material layer and the positive current collector 12 and preventing powder shedding, thereby effectively improving the mass energy density of the battery cell.

[0068] In some embodiments, the positive electrode active material layer 11 includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent, wherein the mass percentage ratio of the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent is (80%~95%):(1%~10%):(1%~10%).

[0069] The positive electrode active material can be selected from one or more combinations of lithium transition metal oxides, including but not limited to: lithium cobalt oxide (LiCoO2, LCO), lithium manganese oxide (such as spinel-type LiMn2O4, LMO), lithium nickel cobalt manganese oxide ternary materials (LiNi x Co y Mn 1-x-y O2, NCM, such as NCM111, NCM523, NCM622, NCM811, lithium nickel cobalt aluminum oxide (LiNi 0.8 Co 0.15 Al 0.05 O2, NCA), lithium iron phosphate (LiFePO4, LFP), lithium nickel manganese spinel (LiNi 0.5 Mn 1.5 O4).

[0070] In LiNi x Co y Mn 1-x-y In O2 materials, 0 < x ≤ 0.9, 0 < y ≤ 0.9, and x + y < 1; typically, x can take values ​​from 0.3 to 0.8, y can take values ​​from 0.1 to 0.3, and z = 1. x y can be taken as 0.1 to 0.4.

[0071] The binder can be selected from polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), and styrene. Butadiene rubber (SBR), etc.; the conductive agent can be selected from one or more of acetylene black, superconducting carbon (Super P), carbon nanotubes (CNT) or graphene.

[0072] Setting the mass percentage of the positive electrode active material in the high range of 80%–95% ensures that the electrode wire can carry a sufficient amount of electrochemical reactants per unit length, thereby effectively improving the mass energy density and capacity of the battery cell. If the active material percentage is too low (<80%), although the electrode flexibility may be improved, it will lead to a significant decrease in battery capacity, failing to meet usage requirements. Since the electrode wire in this application cannot be densified by planar rolling, the bonding force between the active material layer and the current collector mainly depends on the adhesive. Controlling the adhesive percentage to 1%–10% provides sufficient interfacial adhesion to prevent powder shedding or peeling of the active material layer during spiral winding or bending, and also reduces ion transport obstruction and impedance surge caused by excessive adhesive (>10%). Controlling the conductive agent percentage to 1%–10% enables the construction of effective electron transport channels between active material particles. An appropriate amount of conductive agent can significantly reduce electrode polarization and improve the rate performance and low-temperature performance of the battery. If the proportion of conductive agent is too low (<1%), it will lead to poor electron conduction path and excessive internal resistance. If the proportion is too high (>10%), it will occupy the space of active material, reduce the capacity of battery cells, and increase material costs.

[0073] In some embodiments, the negative electrode wire 20 includes a negative current collector 22 and a negative active material layer. The outer peripheral surface of the negative current collector 22 is covered with the negative active material layer. Along the circumferential direction of the negative current collector 22, the negative active material layer wraps around the outer peripheral surface of the negative current collector 22 and extends along the length direction of the current collector. The mass of the negative active material layer ranges from 100 mg / m to 130 mg / m.

[0074] The material of the negative reactive material layer includes one or more of graphite, silicon carbide, and alloys.

[0075] In lithium-ion batteries, to ensure sufficient lithium insertion and avoid lithium dendrite formation at the negative electrode during the first charge-discharge cycle, the reversible capacity provided by the negative electrode typically needs to be slightly higher than the amount of lithium that can be extracted from the positive electrode (i.e., negative-to-positive electrode capacity ratio > 1). Since both the negative electrode wire 20 and the positive electrode wire 10 in this application are wire-coated without rolling, their capacity is primarily determined by the load per unit length of the active material. Setting the load of the negative electrode active material layer 21 to 100 mg / m to 130 mg / m, combined with a positive electrode load of 150 mg / m to 180 mg / m, allows the battery cell to operate within a safe and reasonable negative-to-positive electrode capacity ratio range (typically 1.05 to 1.2), ensuring cycle safety without unnecessary waste of inactive mass due to excessive negative electrode loading. Excessive thickness of the negative electrode active material layer 21 increases the risk of drying shrinkage stress and coating peeling during bending. By controlling the content of the negative electrode active material layer 21 to 100 mg / m to 130 mg / m, the negative electrode wire 20 can maintain good flexibility and coating bonding strength while meeting the capacity matching requirements, and adapt to the requirements of subsequent spiral winding and fiber bending.

[0076] In some embodiments, the negative electrode active material layer 21 includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent, and the mass percentage ratio of the three components is (80% to 95%): (1% to 10%): (1% to 10%).

[0077] The negative electrode active material can be selected from one or more lithium-intercalable materials, including but not limited to: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-carbon composites (Si / C), and silicon-oxygen composites (SiO2). x / C), Lithium titanate (Li4Ti5O) 12 LTO, tin-based alloy or tin oxide anode materials.

[0078] The binder is typically selected from sodium carboxymethyl cellulose (CMC) and styrene. Aqueous system of butadiene rubber (SBR); conductive agent can be selected from superconducting carbon, carbon nanotubes or graphene.

[0079] Setting the mass percentage of the negative electrode active material in the high range of 80%–95% maximizes the reversible lithium intercalation capacity of the negative electrode, thereby improving the battery's initial efficiency and overall energy density. If the active material percentage is too high (>95%), although the initial capacity is slightly improved, the interfacial bonding force between the active material layer and the current collector is significantly reduced due to the decrease in the absolute amount of binder and conductive agent. Furthermore, it cannot effectively buffer the volume expansion stress during cycling, easily leading to powdering or cracking of the active material layer after bending or long cycling. To address the volume expansion effect of the negative electrode material during lithium intercalation, controlling the binder percentage within the range of 1%–10% not only provides the necessary bonding force but also effectively suppresses the radial expansion and deformation of the negative electrode wire 20 during charging and discharging, preventing the spiral winding structure from loosening or the separator from being punctured. If the binder percentage is too low (<1%), the negative electrode wire 20 is prone to pulverization; if the percentage is too high (>10%), it will significantly increase the electrode internal resistance and reduce the energy density. Since the negative electrode wire 20 of this application cannot be coated using a roll forming process, the addition of the conductive agent can also improve the rheological properties of the slurry to a certain extent, and help to uniformly coat the active material layer. This ratio range avoids the dilution of the active material ratio and the decrease in coating density caused by excessive conductive agent (>10%), thereby improving the volumetric energy density of the battery cell.

[0080] In some embodiments, the negative electrode adhesive includes sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), and the mass ratio of sodium carboxymethyl cellulose to styrene-butadiene rubber is controlled within the range of 1: (1.5 to 3).

[0081] Styrene-butadiene rubber (SBR), as the main binder component providing flexibility and elasticity, directly affects the ability of the negative electrode active material layer 21 to resist volume expansion. Setting the SBR to CMC ratio to 1.5–3 ensures sufficient elasticity in the binder system. When the SBR content is closer to the upper limit of this range (e.g., close to 1:3), the negative electrode active material layer 21 exhibits superior flexibility and resilience, effectively buffering the volume expansion stress of silicon-based or high-capacity negative electrode materials during lithium intercalation, preventing cracking or peeling of the active material layer, and is particularly suitable for applications requiring adaptation to large deformations.

[0082] By controlling the CMC to SBR ratio at 1:(1.5~3), the risk of excessively hard and brittle electrodes due to an excessively high CMC ratio is avoided, as is insufficient adhesion due to an excessively low SBR ratio (such as close to 1:1.5). This ratio ensures that the slurry has good wettability and adhesion on the surface of the wire current collector, forming a coating with both rigidity and toughness after drying, reducing powder shedding during subsequent spiral winding and use.

[0083] For battery cells formed by spirally winding different numbers of positive electrode wires 10 and negative electrode wires 20, the measured performance parameters are shown in Table 1. In the table, the electrode assembly 100 of the battery cells in the comparative example and Examples 1 and 2 were measured under the following parameters.

[0084] The positive electrode active material is lithium cobalt oxide, the conductive agent is superconducting carbon black (SP), and the binder is polyvinylidene fluoride (PVDF). The mass ratio of lithium cobalt oxide, SP, and PVDF is 92:3:5. The negative electrode active material is graphite, the conductive agent is SP, and the binders include CMC and SBR. By mass ratio, CMC:SBR is 1.4:3.6, and graphite:SP:binder is 90:5:5. The diameter of the positive current collector 12 is 400 μm, the diameter of the negative current collector 22 is 380 μm, and the thickness of the separator is 15 μm. The pitch of both the positive electrode wire 10 and the negative electrode wire 20 is 5 mm.

[0085] Table 1

[0086] Rate performance (%) = (Battery discharge capacity at 1C constant current charge / discharge) / (Battery discharge capacity at 0.02C constant current charge / discharge) × 100% Here, "C" represents the rate of charge / discharge, referring to the current at which the battery's nominal capacity is equal to its rated capacity (e.g., if the nominal capacity is 10mAh, then 1C = 10mA). 0.02C represents the baseline capacity under near-static conditions, while 1C represents high-current charge / discharge conditions. The larger this ratio, the better the battery's lithium-ion transport and polarization suppression capabilities under high-current conditions.

[0087] SOH (%) is defined as the ratio of the actual discharge capacity of the battery in the current cycle to the initial (week 1) discharge capacity, that is: SOH (%) = (discharge capacity in week n) / (discharge capacity in week 1) × 100%.

[0088] The number of cycles corresponding to when SOH decays to 80% is denoted as the battery's cycle life.

[0089] As can be seen from Table 1 above, using two or more positive electrode wires 10 and two or more negative electrode wires 20, compared to the conventional single positive electrode wire 10 and single negative electrode wire 20 spirally wound together, significantly improves energy density, charge / discharge rate and cycle performance.

[0090] The following describes a battery device according to some embodiments of this application.

[0091] This application proposes a battery device including at least one battery cell as described in the above embodiments. When there are multiple battery cells, the multiple battery cells are electrically connected in series and / or parallel.

[0092] Because the battery cell is flexible and fibrous with a small cross-sectional diameter, the battery device can be further manufactured into the following structural forms according to usage requirements: Fiber bundle / yarn type battery device: Multiple battery cells are bundled together or woven into multi-core fiber bundles, which look similar to ordinary textile yarns and can be subsequently used in weaving, knitting or embroidery. Fabric-integrated battery devices: Multiple battery cells are woven directly into a flexible base fabric as weft or warp yarns to form a flexible and foldable textile battery module. Strip / Cable Battery Device: Multiple battery cells are arranged in parallel and encapsulated in a flexible strip encapsulation layer 200 to form a flexible wearable power strip; Miniature flexible power module: Multiple battery cells and miniature protection circuits are encapsulated together on a flexible polymer substrate to form a miniature power system for smart wearable terminals.

[0093] The following describes a specific example of an electrical device based on some embodiments of this application.

[0094] This application provides an electrical device including the battery device described in the above embodiments, the battery device being used to provide electrical energy to the electrical device.

[0095] Battery devices can be applied to, but are not limited to, smart wearable devices, such as smartwatch 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.

[0096] 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 battery cell, characterized in that, include: An electrode assembly includes a first diaphragm, N positive electrode wires, and N negative electrode wires, where N is an integer greater than or equal to 2. The outer peripheral surface of at least one of the positive electrode wires and the negative electrode wires is covered by the first diaphragm, which insulates the positive electrode wires and the negative electrode wires. The N positive electrode wires and the N negative electrode wires are spirally wound around a first axis to form an electrode bundle. Along the circumferential direction of the first axis, the N positive electrode wires and the N negative electrode wires are staggered, and a negative electrode wire is provided between two adjacent positive electrode wires.

2. The battery cell according to claim 1, characterized in that, The first diaphragm wraps around the outer peripheral surface of the negative electrode wire, and the first diaphragm abuts against two adjacent positive electrode wires circumferentially along the first axis.

3. The battery cell according to claim 2, characterized in that, The outer peripheral diameter D1 of the first diaphragm and the outer peripheral diameter D2 of the positive electrode wire satisfy the following relationship: 1≤D1 / D2≤1.

1.

4. The battery cell according to claim 1, characterized in that, The battery cell also includes an encapsulation layer having a receiving cavity, and the electrode assembly is located within the receiving cavity.

5. The battery cell according to claim 4, characterized in that, The encapsulation layer is a flexible material layer.

6. The battery cell according to claim 1, characterized in that, The pitch of both the positive electrode wire and the negative electrode wire ranges from 2 mm to 8 mm; and / or, the positive electrode wire includes a positive current collector, the diameter of which ranges from 0.1 mm to 0.5 mm; and / or, the negative electrode wire includes a negative current collector, the diameter of which ranges from 0.1 mm to 0.5 mm; and / or, the thickness of the first diaphragm ranges from 2 micrometers to 40 micrometers.

7. The battery cell according to claim 1, characterized in that, The number of electrode bundles is multiple, and the multiple electrode bundles are arranged sequentially along the radial direction of the first axis. In any two adjacent electrode bundles, one electrode bundle wraps around the outer peripheral surface of the other electrode bundle.

8. The battery cell according to any one of claims 1-7, characterized in that, The positive electrode wire includes a positive current collector and a positive active material layer. The outer peripheral surface of the positive current collector is covered by the positive active material layer. Along the circumferential direction of the positive current collector, the positive active material layer wraps around the outer peripheral surface of the positive current collector and extends along the length direction of the positive current collector. The mass of the positive active material layer ranges from 150 mg / m to 180 mg / m.

9. The battery cell according to claim 8, characterized in that, The positive electrode active material layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent, and the mass percentage ratio of the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent is (80%~95%): (1%~10%): (1%~10%).

10. The battery cell according to any one of claims 1-7, characterized in that, The negative electrode wire includes a negative current collector and a negative active material layer. The outer peripheral surface of the negative current collector is covered by the negative active material layer. Along the circumferential direction of the negative current collector, the negative active material layer wraps around the outer peripheral surface of the negative current collector and extends along the length direction of the negative current collector. The mass of the negative active material layer ranges from 100 mg / m to 130 mg / m.

11. The battery cell according to claim 10, characterized in that, The negative electrode active material layer includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent, and the mass percentage ratio of the three components is (80%~95%):(1%~10%):(1%~10%).

12. The battery cell according to claim 11, characterized in that, The negative electrode adhesive includes sodium carboxymethyl cellulose and styrene-butadiene rubber, wherein the mass ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:(1.5-3).

13. A battery device, characterized in that, It includes at least one battery cell as described in any one of claims 1-12, wherein when there are multiple battery cells, the multiple battery cells are electrically connected in series and / or in parallel.

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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