Battery pole group and preparation method thereof, single battery, battery pack and electric device

Abstract

The application provides a battery pole group, a preparation method thereof, a single battery, a battery pack and a power utilization device, and solves the problems of complicated preparation process and low production efficiency of the battery pole group. The battery pole group comprises: a continuous first pole piece, which extends along a first length direction and repeatedly turns back in a thickness direction to form a plurality of first pole piece parts, and the first pole piece extends out first pole lugs at both ends in a second length direction; a continuous second pole piece, which is opposite in polarity, extends along a third length direction and repeatedly turns back in the thickness direction to form a plurality of second pole piece parts, and the second pole piece extends out second pole lugs at both ends in the second length direction; a diaphragm, which is located between the first pole piece and the second pole piece in the thickness direction; two first pole lugs are located on both sides of the first pole piece part, and two second pole lugs are located on both sides of the second pole piece part. The continuous pole piece is directly turned back to form the laminated pole piece part, the pole piece slitting process is omitted, and the production efficiency of the battery cell is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a battery electrode assembly and its preparation method, a single cell, a battery pack, and an electrical device. Background Technology

[0002] In the manufacturing of stacked lithium-ion batteries, the core electrode assembly is typically formed by stacking multiple independent electrode units sequentially. Specifically, an active material is first coated onto the current collector, dried, and then the continuous electrode strip is cut into strips of the required width. These strips are then rolled to increase compaction density, followed by a second precision cut to the size of a single cell, ultimately resulting in a large number of independent, separate positive and negative electrode sheets. These independent electrode sheets must be grasped, transported, positioned, and precisely stacked alternately with a separator to assemble a complete battery electrode assembly.

[0003] The aforementioned "independent electrode manufacturing and stacking" process paradigm dictates that the production process inevitably involves multiple slitting operations and a large amount of material handling and positioning, resulting in numerous production steps and long process times, which has become a key bottleneck restricting battery production capacity and cost control. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide a battery electrode assembly and its preparation method, a single cell, a battery pack, and an electrical device, so as to improve the problem of cumbersome battery electrode assembly preparation process and low production efficiency in the prior art.

[0005] In a first aspect, embodiments of this application provide a battery electrode assembly, comprising: A continuous first electrode extends along a first length direction of the first electrode and repeatedly folds back and forth in the thickness direction of the battery electrode assembly to form a plurality of first electrode portions, and the first electrode extends first tabs at both ends along a second length direction of the battery electrode assembly; A continuous second electrode sheet, with polarity opposite to that of the first electrode sheet, extends along its own third length direction and repeatedly folds back and forth in the thickness direction to form a plurality of second electrode sheet portions, and second electrode tabs extend from both ends of the second electrode sheet along the second length direction; and, A diaphragm, along the thickness direction, is located between the first electrode and the second electrode; Along the thickness direction, a plurality of first electrode portions and a plurality of second electrode portions are alternately stacked; along the length direction, two first electrode tabs are located on both sides of the first electrode portion, and two second electrode tabs are located on both sides of the second electrode portion.

[0006] Optionally, the number of folds of the first electrode, the second electrode, and the diaphragm are all even, and the number of the first electrode portion and the number of the second electrode portion are both odd.

[0007] Optionally, along the folding path of the battery electrode assembly, one of the first tabs is connected to the beginning of the first first electrode portion, and the other first tab is connected to the end of the last first electrode portion; Along the folding path of the battery electrode assembly, one of the second electrode tabs is connected to the beginning of the first second electrode portion, and the other second electrode tab is connected to the end of the last second electrode portion; Along the thickness direction, two first electrodes and two second electrodes are alternately arranged.

[0008] Optionally, the first electrode includes a plurality of first folded segments, and the first electrode portion and the first folded segments are arranged alternately along the extending direction of the first electrode; The second electrode includes a plurality of second folded segments, and the second electrode portion and the second folded segments are arranged alternately along the extending direction of the second electrode; The diaphragm includes a plurality of first isolation segments and a plurality of second isolation segments. Along the extension direction of the diaphragm, the first isolation segments and the second isolation segments are arranged alternately. Along the thickness direction, the first isolation segments are located between the first electrode portion and the second electrode portion, and the second isolation segments are located between the first folded segment and the second folded segment.

[0009] Optionally, the first electrode includes a first current collector and a first active layer. The first current collector is provided with a plurality of first coating sections and a plurality of first bending sections. Along the extending direction of the first current collector, the plurality of first coating sections and the plurality of first bending sections are arranged alternately. The first active layer is disposed on the first coating section to form the first electrode portion. The first bending section is not provided with the first active layer to form the first folded section. The second electrode includes a second current collector and a second active layer. The second current collector is provided with a plurality of second coating sections and a plurality of second bending sections. Along the extension direction of the second current collector, the plurality of second coating sections and the plurality of second bending sections are arranged alternately. The second active layer is provided on the second coating section to form the second electrode portion. The second bending section is not provided with the second active layer to form the second folded section. Along the thickness direction, a first exhaust channel is formed between the first folded section and the second isolation section, and a second exhaust channel is formed between the second folded section and the second isolation section.

[0010] Secondly, embodiments of this application provide a method for preparing a battery electrode assembly, the method being used to prepare the battery electrode assembly as described in the first aspect, the method comprising: A continuous first electrode is provided, the first electrode comprising a plurality of first coated regions and a plurality of first uncoated regions alternately arranged along its own first length direction, and first tabs are formed at both ends of the first length direction; A continuous second electrode sheet is provided, which has the opposite polarity to the first electrode sheet. The second electrode sheet includes a plurality of second coated areas and a plurality of second uncoated areas alternately arranged along its own third length direction, and second tabs are formed at both ends of the third length direction. The first electrode is folded at the first uncoated area to form a plurality of first electrode portions; The second electrode is folded at the second uncoated area to form a plurality of second electrode portions; The folded first electrode portion, separator, and second electrode portion are alternately stacked along the thickness direction of the first electrode portion, so that each pair of adjacent first electrode portions and second electrode portions with opposite polarities are separated by the separator, forming the battery electrode group; and the two first electrode tabs are located on both sides of the first electrode portion along the second length direction of the battery electrode group, and the two second electrode tabs are located on both sides of the second electrode portion along the second length direction.

[0011] Thirdly, embodiments of this application provide a method for preparing a battery electrode assembly, the method being used to prepare the battery electrode assembly as described in the first aspect, the method comprising: A continuous first electrode is provided, the first electrode including a plurality of first coated areas and a plurality of first uncoated areas alternately arranged along its own first length direction, and first tabs are formed at both ends of the first electrode along its length direction. A continuous second electrode sheet is provided, which has the opposite polarity to the first electrode sheet. The second electrode sheet includes a plurality of second coated areas and a plurality of second uncoated areas alternately arranged along its own third length direction, and second tabs are formed at both ends of the third length direction. The first electrode, the diaphragm, and the second electrode are sequentially stacked to form a composite component; The composite component is folded at the first uncoated area and the second uncoated area, such that the first coated area and the second coated area are alternately arranged in the thickness direction of the composite component to form a plurality of first electrode portions and second electrode portions that are alternately stacked in the thickness direction. Each pair of adjacent first electrode portions and second electrode portions with opposite polarities is separated by the separator to form the battery electrode group. Two first electrode tabs are located on both sides of the first electrode portion along the second length direction of the battery electrode group, and two second electrode tabs are located on both sides of the second electrode portion along the second length direction.

[0012] Fourthly, embodiments of this application provide a single-cell battery, comprising: The battery electrode assembly as described in the first aspect; or... Such as the battery electrode assembly prepared in the second aspect; or, Such as the battery electrode assembly prepared in the third aspect.

[0013] Fifthly, embodiments of this application provide a battery pack including at least one single cell as described in the fourth aspect.

[0014] Sixthly, embodiments of this application provide an electrical appliance, including: Electricity-consuming entities; The battery pack as described in the fifth aspect is electrically connected to the power-consuming body.

[0015] To address the technical problem of cumbersome and inefficient manufacturing processes caused by stacking multiple independent electrode sheets in stacked lithium-ion batteries, this application adopts a continuous first electrode sheet and a second electrode sheet. The first electrode sheet extends along the length direction and is repeatedly folded back and forth in the thickness direction to form multiple stacked first electrode sheet portions. Similarly, the second electrode sheet extends along the length direction and is repeatedly folded back and forth in the thickness direction to form multiple stacked second electrode sheet portions. A separator is used to separate the first electrode sheet portion and the second electrode sheet portion along the thickness direction. The first electrode tab and the second electrode tab extend from both ends of the first electrode sheet and the second electrode sheet respectively and are located on both sides of the stacked electrode sheet portion, forming a folded electrode assembly structure. This eliminates the need to first cut the electrode sheet into multiple segments before stacking, thereby saving the first and second cutting processes, simplifying the production process, and improving the stacking speed and overall production efficiency of the battery cell. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an electrical device provided for some embodiments of this application.

[0017] Figure 2 for Figure 1 A cross-sectional view of the battery pack of the electrical equipment shown.

[0018] Figure 3This is a schematic diagram of the structure of a battery electrode assembly provided in some embodiments of this application.

[0019] Figure 4 for Figure 3 The diagram shows the structure of the first electrode in the battery electrode assembly when it is not folded.

[0020] Figure 5 for Figure 3 The diagram shows the structure of the second electrode in the battery electrode assembly when it is not folded.

[0021] Explanation of reference numerals in the attached figures: 100. Electrical equipment; 110. Main power supply unit; 110a. Battery compartment; 120. Battery pack; 121. Housing; 121a. First inner cavity; 122. Single cell; 1. Battery electrode assembly; 11. First electrode; 111. First electrode portion; 112. First folded section; 113. First current collector; 1131. First coated section; 1132. First bent section; 114. First active layer; 12. Second electrode; 121. Second electrode portion; 122. Second folded section; 123. Second current collector; 1231. Second coated section; 1232. Second bent section; 124. Second active layer; 13. Separator; 131. First insulating section; 132. Second insulating section; 14. First tab; 15. Second tab; 16. First venting channel; 17. Second venting channel; X1, First length direction; X2, Second length direction; X3, Third length direction; Z, Thickness direction. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. It is understood that the implementation schemes described and shown herein are non-limiting examples. It should be noted that, without contradiction, the technical features in different embodiments can be freely combined.

[0023] Please see Figure 1 , Figure 1 This is a schematic diagram of an electrical device 100 provided in some embodiments of this application. Figure 1In the illustrated embodiment, an electric vehicle is used as an example of the electrical device 100 for illustrative purposes, and this should not be construed as a specific limitation of this application. In other embodiments, the electrical device may also be a mobile phone, a laptop computer, a mobile charging station, or other similar devices.

[0024] Please continue reading. Figure 1 The electrical device 100 includes a power-consuming body 110 and a battery pack 120. The battery pack 120 is fixed to the power-consuming body 110 and electrically connected to the power-consuming components of the power-consuming body 110 to supply power to the power-consuming components of the power-consuming body 110. Specifically, the power-consuming body 110 may have a battery compartment 110a, and the battery pack 120 is fixed inside the battery compartment 110a.

[0025] Please see Figure 2 , Figure 2 for Figure 1 The diagram shows a cross-sectional view of the battery pack 120 of the electrical device 100. The battery pack 120 may include a housing 140 and at least one row of individual battery cells 142. The housing 140 encloses a first inner cavity 141. The individual battery cells 142 are disposed in the first inner cavity 141 of the housing 140 and fixed relative to the housing 140. The housing 140 protects the individual battery cells 142 from external forces causing vibration and impact that could damage them. The housing 140 may be a metal or plastic structural component.

[0026] A single cell 142 is the most basic electrochemical unit, capable of storing and releasing electrical energy. Single cells 142 can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0027] Figure 2 In the battery pack 120 shown, there are multiple individual cells 142. These individual cells 142 can be electrically connected in series, in parallel, or in a mixed configuration. A mixed configuration means that the individual cells 142 are connected in both series and parallel relationships, which can be specifically designed according to the power requirements of the electrical device 100. In some other embodiments, the battery pack 120 may contain only one individual cell 142.

[0028] The single-cell battery 142 includes a casing and a battery electrode assembly 1. The casing has a receiving cavity and a first opening communicating with the receiving cavity. The receiving cavity is used to receive the electrode assembly and electrolyte. The first opening is used to place the battery electrode assembly within the receiving cavity.

[0029] The outer casing can be generally rectangular in shape, so that the individual battery 142 is also generally rectangular. The outer casing can be a metal casing. In some examples, the casing can be an aluminum alloy casing, so that the casing has a lighter weight, which is beneficial to the lightweight of the individual battery 142, and thus to the overall lightweight of the electrical device 100. In other examples, the casing can also be a stainless steel casing, a titanium alloy casing, etc., so that the casing has higher strength, which in turn gives the individual battery 142 better strength and stronger resistance to puncture and vibration damage. In other embodiments, the shape of the casing can also be cylindrical, irregular, etc.

[0030] Battery electrode assembly 1 is disposed within the receiving cavity and immersed in the electrolyte. To address the problems of cumbersome battery electrode assembly fabrication processes and low production efficiency in existing technologies, please refer to [link to relevant documentation]. Figure 3 The battery electrode assembly 1 has a second length direction X2 and a thickness direction Z, and the thickness direction Z is generally perpendicular to the second length direction X2.

[0031] Battery electrode assembly 1 can be used in lithium-ion batteries as the core of electrochemical power generation within the battery. The basic components of battery electrode assembly 1 include a continuous first electrode 11, a continuous second electrode 12, and a separator 13. The first electrode 11 and the second electrode 12 have opposite polarities; one can serve as the positive electrode, and the other as the negative electrode. The separator 13 is located between the first electrode 11 and the second electrode 12, spatially separating the positive and negative electrodes while allowing ions from the electrolyte to pass through.

[0032] The battery electrode assembly 1 includes a continuous first electrode 11. The first electrode 11 extends along its first length direction X1 and repeatedly folds back and forth in the thickness direction Z of the battery electrode assembly 1 to form a plurality of first electrode portions 111 arranged along the thickness direction Z. First tabs 14 extend from both ends of the first electrode 11 along the second length direction X2 of the battery electrode assembly 1. The first tabs 14 are used for electrical connection with an external circuit or bus structure.

[0033] The battery electrode assembly 1 also includes a continuous second electrode 12 with opposite polarity to the first electrode 11. The second electrode 12 extends along its third length direction X3 and repeatedly folds back and forth in the thickness direction Z, forming multiple second electrode portions 121 arranged along the thickness direction Z. Second tabs 15 extend from both ends of the second electrode 12 along the second length direction X2 of the battery electrode assembly 1. A separator 13 is located between the first electrode 11 and the second electrode 12 along the thickness direction Z, separating all the first electrode portions 111 and the second electrode portions 121. Viewed along the second length direction X2, two first tabs 14 are located on both sides of the first electrode portion 111, and two second tabs 15 are located on both sides of the second electrode portion 121.

[0034] It should be explained that the continuity of the first electrode 11 means that the electrode is a continuous whole in physical form, not composed of multiple separate sheets spliced ​​together. The first electrode 11 extends along the first length direction X1, meaning that its main body spreads along the first length direction X1, while its folding action occurs in the thickness direction Z. This arrangement makes the two ends of the electrode in the first length direction X1 the optimal locations for leading out the tabs. The first electrode portion 111 refers to the main planar region of the first electrode 11 after folding, which is substantially parallel to the plane defined by the second length direction X2 and the width direction. These regions are the main sites of electrochemical reactions. The structure and operation of the second electrode 12 correspond to the first electrode 11; its continuity, extension, folding, and the formation of the second electrode portion 121 are consistent with the first electrode 11. The two second tabs 15 also extend from both ends of the second length direction X2. The separator 13 is a porous insulating film made of polyethylene, polypropylene, or a composite thereof, and its thickness is less than that of the first electrode portion 111 and the second electrode portion 121. The separator 13 separates the positive and negative electrodes in the thickness direction Z and remains continuous along the extension direction of the electrodes, folding back along with the electrodes. Along the thickness direction Z, multiple first electrode portions 111 and multiple second electrode portions 121 are alternately stacked.

[0035] Through the above construction, continuous electrode sheets are directly folded back to form a folded electrode group structure for the stacked electrode section. This eliminates the need to first cut the electrode sheets into multiple segments before stacking, thus saving the traditional slitting processes such as first-stage and second-stage cutting, simplifying the production process, and significantly improving the cell stacking speed and overall production efficiency. The first tab 14 and the second tab 15 are led out from both ends in the length direction X, facilitating busbar connection when multiple electrode groups are connected in parallel.

[0036] In another possible configuration, the number of folds in the first electrode 11 and the second electrode 12 can be adjusted according to the cell capacity requirements, for example, forming three, five, seven or more stacked electrode sections. The tabs can also be led out at both ends along the length with different widths and shapes to accommodate different busbar requirements. The separator 13 can also be composed of multiple layers of different materials to provide superior thermal closure performance.

[0037] To more reliably enable the first tab 14 and the second tab 15 to be led out from different sides of the battery electrode group 1, facilitate external bus connections, and avoid congestion of the tab leads, the number of folds of the first electrode 11, the second electrode 12, and the separator 13 can be set to an even number, in which case the number of first electrode portions 111 and second electrode portions 121 are both odd.

[0038] The number of folds refers to the total number of times the electrode changes direction in the thickness direction Z. When a continuous electrode sheet is started from one end, it is first bent to form an electrode portion, then bent in the opposite direction to form a second electrode portion, and so on. If an even number of bends are performed, the two ends of the electrode sheet will be located on different sides of the entire stack or on the same side, depending on the starting position and the specific folding method. By limiting the number of folds to an even number, and ensuring that the number of first electrode portions 111 and second electrode portions 121 are both odd, it can be reliably guaranteed that the starting and ending ends of the first electrode 11 are located at opposite ends of the battery electrode assembly 1 in the second length direction X2, thus ensuring that the first tabs 14 located at the starting and ending ends are located on both sides of the first electrode portion 111. The same principle applies to the second electrode 12 and the second tab 15. This achieves a reliable opposite-side tab arrangement. For example, if the number of folds is 4, 6, or 8, the corresponding number of first electrode portions 111 is 5, 7, or 9.

[0039] This design ensures that tabs of different polarities are naturally distributed on different end faces of the laminate, avoiding the space constraints and connection difficulties caused by leading all tabs out on the same side. When multiple battery electrode groups 1 are connected in parallel to form a battery pack, tabs of the same polarity on the same side can be easily connected by the same busbar, while the opposite-side arrangement increases the spatial distance between busbars of different polarities, improving safety and reliability. The opposite-side tab arrangement also facilitates the arrangement of the cold plate in the battery thermal management system, allowing for a more efficient cooling solution to be arranged on the tabless side.

[0040] In another possible configuration, the number of folds may not be even. By adjusting the starting and ending positions of the electrode plates, or the extension length in the longitudinal direction, the lead-out position of the electrode tabs can also be controlled to some extent.

[0041] To arrange the tabs of different polarities more orderly along the thickness direction Z, increase the creepage distance between tabs of opposite polarities, reduce the risk of short circuits, and facilitate current sharing and collection for each electrode section, one first tab 14 can be connected to the beginning of the first first electrode section 111, and the other first tab 14 is connected to the end of the last first electrode section 111, viewed along the folding path of the battery electrode group 1. Similarly, one second tab 15 is connected to the beginning of the first second electrode section 121, and the other second tab 15 is connected to the end of the last second electrode section 121, viewed from the thickness direction Z. The two first tabs 14 and the two second tabs 15 are intersecting.

[0042] The folding path starts from the beginning of the first electrode 11 and proceeds along the extension direction of the electrode, sequentially passing through the first bend, the first first electrode portion 111, the second bend, the second first electrode portion 111, and finally the end of the last first electrode portion 111. By confining the first tab 14 to both ends of the folding path, the tab is prevented from being drawn out in the middle of the first electrode 11, maximizing the utilization of the electrode material. Furthermore, this configuration of tabs at both ends, combined with the corresponding configuration of the second electrode 12, naturally forms an alternating tab layout in the thickness direction Z. Viewed from the stacking direction, i.e., along the thickness direction Z, the first tab 14 and the second tab 15 appear alternately. This increases the spatial distance between tabs of different polarities, especially the creepage surface distance, effectively reducing the risk of short circuits inside the battery due to factors such as cell expansion, impurities, or electrolyte leakage. Simultaneously, the orderly tab arrangement facilitates subsequent ultrasonic welding or laser welding processes, which is beneficial for automated production.

[0043] To ensure electrical isolation throughout the entire path of the electrode folding, especially at bends, and to prevent direct contact between the positive and negative electrodes from causing internal short circuits, the first electrode 11 may include multiple first folded segments 112 and multiple first electrode portions 111, with the first electrode portions 111 and first folded segments 112 alternating along the extending direction of the first electrode 11. Correspondingly, the second electrode 12 includes multiple second folded segments 122 and multiple second electrode portions 121, with the second electrode portions 121 and second folded segments 122 alternating along the extending direction of the second electrode 12. The diaphragm 13 is divided into multiple first isolation segments 131 and multiple second isolation segments 132, with the first isolation segments 131 and second isolation segments 132 alternating along the extending direction of the diaphragm 13. In the thickness direction Z, the first isolation segment 131 is located between the first electrode portions 111 and the second electrode portions 121, undertaking the main isolation function. The second isolation segment 132 is located between the first folded segments 112 and the second folded segments 122, providing isolation for the bends.

[0044] The first folded segment 112 is a transitional curved portion on the first electrode 11 connecting two adjacent first electrode portions 111, and its shape can be arc-shaped, U-shaped, or V-shaped. The first electrode portion 111 is the main planar section on the electrode coated with the active material. The alternating arrangement of the two defines the folded configuration of the electrode. The second folded segment 122 and the second electrode portion 121 of the second electrode 12 correspond to this structure. The first isolation segment 131 of the diaphragm 13 is the planar coverage area corresponding to the first electrode portion 111 and the second electrode portion 121, while the second isolation segment 132 is the curved coverage area corresponding to the first folded segment 112 and the second folded segment 122. By clearly defining these sections in the design and manufacturing process, it can be ensured that the second isolation section 132 of the diaphragm 13 precisely follows the shape of the first folded section 112 and the second folded section 122, and fits tightly with them or maintains a small, uniform gap. Thus, at the folding and turning points of the electrode, there is always an insulating diaphragm between the exposed solids of the positive and negative electrodes, preventing local direct contact between the positive and negative electrodes caused by diaphragm displacement or wrinkling during the folding process, which is beneficial to improving the insulation reliability inside the electrode assembly.

[0045] Alternatively, the length ratio of the first folded section 112 to the first electrode portion 111 can be adjusted according to the thickness and energy density requirements of the electrode assembly. The second insulating section 132 of the diaphragm can be designed to have higher ductility or porosity than the first insulating section 131 to accommodate bending deformation.

[0046] To establish a through-channel venting system within the battery cell in the event of extreme conditions such as thermal runaway, preventing the explosion-proof valve from failing due to blockage of gaps caused by active layer expansion, and to improve electrolyte wetting and storage. Please see [link to relevant documentation]. Figure 4 and Figure 5 The first current collector 113 of the first electrode 11 can be divided into multiple first coated sections 1131 and multiple first bent sections 1132. Along the extending direction of the first current collector 113, the multiple first coated sections 1131 and multiple first bent sections 1132 are arranged alternately. A first active layer 114 is only provided on the first coated sections 1131, and these portions form the first electrode portion 111. The first bent sections 1132 do not have the first active layer 114, thus forming a first folded section 112. The second electrode 12 correspondingly includes a second current collector 123 and a second active layer 124. The second current collector 123 is divided into multiple second coated sections 1231 and multiple second bent sections 1232, which are arranged alternately along its extending direction. The second active layer 124 is only provided on the second coated sections 1231, forming the second electrode portion 121. The second bent sections 1232 do not have the second active layer 124, thus forming a second folded section 122. In the thickness direction Z, a first exhaust channel 17 is formed between the first folded section 112, which is not covered by an active layer, and the second isolation section 132 of the diaphragm 13. Correspondingly, a second exhaust channel 16 is formed between the second folded section 122 and the second isolation section 132.

[0047] The first current collector 113 is a metal foil, such as aluminum or copper foil, that carries the first active layer 114. The first coated section 1131 is the area whose surface is covered with active material, and the first bent section 1132 is the area that is intentionally left blank and uncoated with active material. The first active layer 114 contains active materials, conductive agents, and binders that can reversibly insert and extract lithium ions. When the battery is fully charged or overheated, both the first active layer 114 and the second active layer 124 will experience significant volume expansion in the thickness direction. Since the first electrode portion 111 and the second electrode portion 121 are tightly stacked, this expansion will severely compress the gap between adjacent electrode portions. However, at the first folded section 112, since there is no active layer, there is no volume expansion problem, and the small gaps between it and the separator 13, and between the separator 13 and the second folded section 122, are retained. These gaps form a first venting channel 17 and a second venting channel 16 that run through the width direction at each bend of the folded area. When gas is generated inside the battery cell due to side reactions, the gas can flow rapidly along these channels to the top edge of the cell, eventually reaching the explosion-proof valve. This allows the valve to open in time to release pressure and prevent the battery from exploding. Simultaneously, these unused current collector areas serve as additional storage space for excess electrolyte, helping to extend the battery's cycle life.

[0048] In a preferred embodiment, the first folded segment 112 and the first bent segment 1132 can be designed with multiple overlapping layers to enhance structural stability, while still maintaining sufficient gaps. More alternatively, the current collector surface in the blank area can be roughened to enhance its ability to adsorb electrolyte.

[0049] This application also provides a method for preparing the battery electrode assembly 1 as described above, specifically including a preparation method of first folding and then stacking the electrodes.

[0050] In this method, a continuous first electrode 11 is first provided. The first electrode 11 includes a plurality of first coated regions and a plurality of first uncoated regions alternately arranged along its first length direction X1, and first tabs 14 are pre-formed at both ends of the first length direction X1. Simultaneously, a continuous second electrode 12 with opposite polarity to the first electrode 11 is provided. The second electrode 12 includes a plurality of second coated regions and a plurality of second uncoated regions alternately arranged along its third length direction X3, and second tabs 15 are pre-formed at both ends of its third length direction X3. Then, the first electrode 11 is folded at the first uncoated regions to form a plurality of first electrode portions 111 arranged along the thickness direction. The second electrode 12 is folded at the second uncoated regions to form a plurality of second electrode portions 121 arranged along the thickness direction. Finally, the folded first electrode portions 111, the separator 13, and the folded second electrode portions 121 are alternately stacked along the thickness direction Z, such that each pair of adjacent first electrode portions 111 and second electrode portions 121 with opposite polarities are separated by the separator 13, forming the battery electrode assembly 1. Furthermore, two first tabs 14 are located on both sides of all the first electrode portions 111 along the second length direction X2 of the battery electrode assembly 1, and two second tabs 15 are located on both sides of all the second electrode portions 121 along the second length direction X2.

[0051] In this method, the first coated area and the first uncoated area correspond to the subsequently formed first coated section 1131 and first bent section 1132, or the first electrode portion 111 and the first folded section 112, respectively. Folding at the first uncoated area means that the folding action occurs precisely at the bending section of the flexible current collector without the active layer covering it. This avoids problems such as powder shedding and cracking of the active layer during bending, ensuring the integrity of the electrode and the yield of the electrode assembly. By adopting the assembly method of first folding the positive and negative electrodes back into shape separately and then performing alternating insert-type stacking, the process steps are clear, and it is easy to control the alignment and tension of each electrode portion. The process parameters of the positive and negative electrode folding back, such as the radius and temperature of the folding blade, can be optimized separately to obtain a neater bending shape.

[0052] The above preparation method requires only one continuous folding action to form multiple stacked electrode portions, replacing the traditional multi-step process of die-cutting electrodes into single sheets and then stacking them one by one, significantly shortening the stacking process time. By selecting the folding point in the uncoated area, the flexibility of the area without active material is utilized for bending, effectively preventing coating peeling.

[0053] Alternatively, the steps of folding the first electrode 11 and folding the second electrode 12 can be performed in parallel to further shorten the manufacturing cycle. The diaphragm 13 can be a pre-folded corrugated diaphragm or a flat diaphragm that is bent along with the first electrode portion 111 and the second electrode portion 121 when they are stacked.

[0054] This application also provides another method for preparing battery electrode assembly 1, which is a method of first compositing the electrode sheet and the separator into one piece and then folding the whole assembly.

[0055] The method first provides a continuous first electrode 11 and a continuous second electrode 12, with the polarity opposite to that of the first electrode 11. Both electrodes are divided into coated and uncoated areas as described above, and have tabs at their longitudinal ends. Next, the first electrode 11, separator 13, and second electrode 12 are sequentially stacked from top to bottom or bottom to top to form an unclamped strip-shaped composite assembly. Then, this composite assembly is integrally folded at the first uncoated area of ​​the first electrode 11 and the second uncoated area of ​​the second electrode 12. During the folding process, the first and second coated areas are alternately arranged in the thickness direction Z, ultimately forming multiple first electrode portions 111 and second electrode portions 121 stacked along the thickness direction Z. Each adjacent first electrode portion 111 and second electrode portion 121 with opposite polarities is pre-separated by a separator 13 to form the battery electrode assembly 1. Finally, the two first tabs 14 are located on both sides of the first electrode portion 111 along the second length direction X2 of the battery electrode group 1, and the two second tabs 15 are located on both sides of the second electrode portion 121 along the second length direction X2.

[0056] This method of layering and then folding completes the relative positioning and pre-bonding of the positive electrode, separator, and negative electrode before the formal bending and forming. Pre-bonding can be achieved through methods such as rolling and hot pressing, making the composite component a single strip. Then, the entire strip is simultaneously bent in the designed blank folding area. The advantage of this is that the separator 13 is always sandwiched between the first electrode 11 and the second electrode 12 throughout the process, fundamentally avoiding the risk of separator displacement or wrinkling in subsequent stacking processes, ensuring full coverage of the electrode by the separator, especially at the bending apex, where the second separating section 132 of the separator 13 can precisely separate the first folding section 112 and the second folding section 122. Since the positive and negative electrodes and the separator are bent together, the adhesion between adjacent layers is higher, which helps to reduce interface resistance and makes the final battery electrode assembly 1 more consistent and neat in the thickness direction Z.

[0057] This overall folding method further simplifies the assembly logic, reduces the complex operations of multi-axis robots, and allows multiple stacked pairs to be formed in one go, thereby improving the production cycle time.

[0058] In an alternative approach, the first electrode 11 and the second electrode 12 can be pre-bent to create creases before forming the composite assembly, thus guiding a more precise overall folding path. The heating temperature during folding can also be precisely controlled to prevent the diaphragm micropores from closing while securing the diaphragm.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery electrode assembly, characterized in that, include: A continuous first electrode extends along a first length direction of the first electrode and repeatedly folds back and forth in the thickness direction of the battery electrode assembly to form a plurality of first electrode portions, and first tabs extend from both ends of the first electrode along a second length direction of the battery electrode assembly. A continuous second electrode sheet with opposite polarity to the first electrode sheet extends along its own third length direction and repeatedly folds back and forth in the thickness direction to form a plurality of second electrode sheet portions, and second electrode tabs extend from both ends of the second electrode sheet along the second length direction; as well as, A diaphragm, along the thickness direction, is located between the first electrode and the second electrode; Along the thickness direction, a plurality of first electrode portions and a plurality of second electrode portions are alternately stacked; along the second length direction, two first electrode tabs are located on both sides of the first electrode portion, and two second electrode tabs are located on both sides of the second electrode portion.

2. The battery electrode assembly according to claim 1, characterized in that, The number of folds of the first electrode, the second electrode, and the diaphragm is all even, and the number of the first electrode portion and the number of the second electrode portion are both odd.

3. The battery electrode assembly according to claim 1, characterized in that, Along the folding path of the battery electrode assembly, one of the first tabs is connected to the beginning of the first first electrode portion, and the other first tab is connected to the end of the last first electrode portion; Along the folding path of the battery electrode assembly, one of the second electrode tabs is connected to the beginning of the first second electrode portion, and the other second electrode tab is connected to the end of the last second electrode portion; Along the thickness direction, two first electrodes and two second electrodes are alternately arranged.

4. The battery electrode assembly according to claim 1, characterized in that, The first electrode includes a plurality of first folded segments, and the first electrode portion and the first folded segments are arranged alternately along the extending direction of the first electrode. The second electrode includes a plurality of second folded segments, and the second electrode portion and the second folded segments are arranged alternately along the extending direction of the second electrode; The diaphragm includes a plurality of first isolation segments and a plurality of second isolation segments. Along the extension direction of the diaphragm, the first isolation segments and the second isolation segments are arranged alternately. Along the thickness direction, the first isolation segments are located between the first electrode portion and the second electrode portion, and the second isolation segments are located between the first folded segment and the second folded segment.

5. The battery electrode assembly according to claim 4, characterized in that, The first electrode includes a first current collector and a first active layer. The first current collector is provided with a plurality of first coating sections and a plurality of first bending sections. Along the extension direction of the first current collector, the plurality of first coating sections and the plurality of first bending sections are arranged alternately. The first active layer is provided on the first coating section to form the first electrode portion. The first bending section is not provided with the first active layer to form the first folded section. The second electrode includes a second current collector and a second active layer. The second current collector is provided with a plurality of second coating sections and a plurality of second bending sections. Along the extension direction of the second current collector, the plurality of second coating sections and the plurality of second bending sections are arranged alternately. The second active layer is provided on the second coating section to form the second electrode portion. The second bending section is not provided with the second active layer to form the second folded section. Along the thickness direction, a first exhaust channel is formed between the first folded section and the second isolation section, and a second exhaust channel is formed between the second folded section and the second isolation section.

6. A method for preparing a battery electrode assembly, characterized in that, The method is used to prepare the battery electrode assembly according to any one of claims 1-5, and the method includes: A continuous first electrode is provided, the first electrode comprising a plurality of first coated regions and a plurality of first uncoated regions alternately arranged along its own first length direction, and first tabs are formed at both ends of the first length direction; A continuous second electrode sheet is provided, which has the opposite polarity to the first electrode sheet. The second electrode sheet includes a plurality of second coated areas and a plurality of second uncoated areas alternately arranged along its own third length direction, and second tabs are formed at both ends of the third length direction. The first electrode is folded at the first uncoated area to form a plurality of first electrode portions; The second electrode is folded at the second uncoated area to form a plurality of second electrode portions; The folded first electrode portion, separator, and second electrode portion are alternately stacked along the thickness direction of the first electrode portion, so that each pair of adjacent first electrode portions and second electrode portions with opposite polarities are separated by the separator to form a battery electrode group; and two first electrode tabs are located on both sides of the first electrode portion along the second length direction of the battery electrode group, and two second electrode tabs are located on both sides of the second electrode portion along the second length direction.

7. A method for preparing a battery electrode assembly, characterized in that, The method is used to prepare the battery electrode assembly according to any one of claims 1-5, and the method includes: A continuous first electrode is provided, the first electrode comprising a plurality of first coated regions and a plurality of first uncoated regions alternately arranged along its own first length direction, and first tabs are formed at both ends of the first length direction; A continuous second electrode sheet is provided, which has the opposite polarity to the first electrode sheet. The second electrode sheet includes a plurality of second coated areas and a plurality of second uncoated areas alternately arranged along its own third length direction, and second tabs are formed at both ends of the third length direction. The first electrode, the diaphragm, and the second electrode are sequentially stacked to form a composite component; The composite component is folded at the first uncoated area and the second uncoated area, such that the first coated area and the second coated area are alternately arranged in the thickness direction of the composite component to form a plurality of first electrode portions and second electrode portions that are alternately stacked in the thickness direction. Each pair of adjacent first electrode portions and second electrode portions with opposite polarities is separated by the separator to form the battery electrode group. Two first electrode tabs are located on both sides of the first electrode portion along the second length direction of the battery electrode group, and two second electrode tabs are located on both sides of the second electrode portion along the second length direction.

8. A single-cell battery, characterized in that, include: The battery electrode assembly as described in any one of claims 1 to 5; or, The battery electrode assembly prepared by the method as described in claim 6; or, The battery electrode assembly prepared by the method of claim 7.

9. A battery pack, characterized in that, include: At least one single cell as described in claim 8.

10. An electrical appliance, characterized in that, include: Electricity-consuming entities; The battery pack as described in claim 9 is electrically connected to the power-consuming body.

Images