A battery pole piece and a battery

Abstract

This invention discloses a battery electrode and a battery, relating to the field of battery manufacturing technology. The battery electrode includes a current collector and multiple tabs spaced apart along the length of the current collector. Each tab has a first side edge and a second side edge arranged opposite each other along its length. A first root fillet is formed at the connection between the first side edge and the current collector, and a second root fillet is formed at the connection between the second side edge and the current collector, wherein the radius of the first root fillet is larger than the radius of the second root fillet. Furthermore, the inclination angle of the first side edge towards the central axis of the tab is smaller than the inclination angle of the second side edge. This invention aims to solve the problem of tabs easily folding during high-speed conveying and winding processes in the prior art by optimizing the streamlined morphology and root stress distribution of the tabs, and by incorporating a differentiated tab assembly design at the feed end and the winding end, thereby improving the manufacturing yield and safety of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a battery electrode and a battery. Background Technology

[0002] Batteries are widely used in automotive power batteries and other fields due to their high energy density and long cycle life. In existing battery electrode manufacturing and winding processes, the tabs typically employ a symmetrical rectangular or trapezoidal structure design, with the root rounded corners and side edge inclination angles usually consistent left and right. However, during the high-speed conveyor belt transport and entry into the winding floating roller, this symmetrical tab structure is highly susceptible to folding at the root due to sudden stress changes and stress concentration when cutting into and out of the guide roller contact surface, thus forming a crescent-shaped crease at the root. This folding not only reduces the cell manufacturing yield, but in severe cases, the folded tab can be drawn into the cell, puncturing the separator and causing an internal short circuit, posing a serious safety hazard.

[0003] Therefore, how to optimize the tab structure to eliminate the risk of flipping during high-speed tape transport, thereby improving the safety and production yield of the battery cells, has become an urgent technical problem to be solved. Summary of the Invention

[0004] The main objective of this invention is to provide a battery electrode and a battery that aims to improve the safety and production yield of the battery cell by optimizing the electrode structure to eliminate the risk of flipping during high-speed conveying.

[0005] To achieve the above objectives, the present invention proposes a battery electrode sheet, comprising a current collector and a plurality of tabs spaced apart along the length direction of the current collector; each tab has a first side edge and a second side edge disposed opposite to each other along the length direction; the edge at which the first side edge connects with the current collector forms a first root fillet, and the edge at which the second side edge connects with the current collector forms a second root fillet, wherein the radius of the first root fillet is greater than the radius of the second root fillet; the first side edge is inclined toward the central axis of the tab to form a first tilt angle, and the second side edge is inclined toward the central axis of the tab to form a second tilt angle, wherein the angle value of the first tilt angle relative to the edge of the current collector is less than the angle value of the second tilt angle relative to the edge of the current collector.

[0006] Preferably, the angle value of the first tilt angle is... , The angle value of the second tilt angle is , .

[0007] Preferably, the radius of the first root fillet is , The radius of the second root fillet is , .

[0008] Preferably, the electrode tab further has a top edge connecting the first side edge and the second side edge; the edge where the first side edge connects to the top edge forms a first top rounded corner, and the edge where the second side edge connects to the top edge forms a second top rounded corner; the radius of the first top rounded corner is [missing information]. , The radius of the second top rounded corner is , .

[0009] Preferably, the plurality of tabs includes a main tab group distributed along the length direction of the current collector, an inlet tab group located at the electrode inlet end, and a tail tab group located at the electrode outlet end; the root width of the tab in the main tab group at the connection point with the current collector is [missing information]. , .

[0010] Preferably, the width of the top edge of the electrode in the main electrode assembly is , The height of the electrode in the main electrode assembly is... , .

[0011] Preferably, the tab assembly consists of four tabs arranged sequentially along the direction away from the feed end, and the root widths of the four tabs are sequentially [missing information]. , , , , , and , .

[0012] Preferably, the terminal electrode assembly consists of six electrodes arranged sequentially along the direction close to the terminal end, and the root widths of the six electrodes are sequentially as follows: , , , , , , , , , and , .

[0013] Preferably, the height of the last two electrodes in the tail electrode assembly is... , .

[0014] This application also discloses a battery, including the battery electrode as described in any of the above.

[0015] The above technical solution has the following advantages: This invention creates an asymmetric streamlined shape in the feeding direction by setting the radius of the first root fillet at the connection between the first side edge of the tab and the current collector to be larger than the radius of the second root fillet at the connection between the second side edge and the current collector, and setting the inclination angle of the first side edge towards the central axis of the tab to be smaller than the inclination angle of the second side edge. This structural design, with a gentler incline and a steeper rear, effectively disperses stress concentration at the root of the tab during high-speed conveyor belt movement. In particular, the gentler incline angle of the first side edge and the larger root fillet significantly reduce the impact resistance when the tab cuts into the roller, while the steeper incline angle of the second side edge ensures structural rigidity and springback stability when the tab leaves the contact area. This significantly reduces the folding rate of the tab during winding, eliminates the risk of crescent-shaped creases at the root of the tab, and effectively improves the manufacturing yield and safety of the battery. Attached Figure Description

[0016] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the battery electrode provided in an embodiment of the present invention. Detailed Implementation

[0017] 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 merely some, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort should fall within the scope of protection of the present application.

[0018] Example 1 like Figure 1 As shown, this embodiment provides a battery electrode sheet, specifically applied in a square aluminum-cased lithium iron phosphate battery system. Of course, its structural design concept can also be applied to other types of wound batteries. This battery electrode sheet mainly consists of a current collector and multiple tabs spaced apart along the length of the current collector. The current collector, as a carrier of the active material and a current collector, is typically made of metal foil; for the positive electrode of a lithium iron phosphate battery, the current collector is specifically made of aluminum foil.

[0019] In the structural layout of the electrode sheet, multiple tabs 30 extend outward from one edge of the current collector. To facilitate the description of the force state of the tabs 30 during the electrode sheet's movement, we define the two edges of the tabs 30 along the length of the electrode sheet as the first side edge 10 and the second side edge 20, respectively. In this embodiment, the feeding direction of the electrode sheet during manufacturing is defined as the reference. The first side edge 10 corresponds to the side where the tab 30 first contacts the roller pressing or passing mechanism when moving with the current collector, i.e., the cutting-in side; while the second side edge 20 corresponds to the side where the tab 30 later contacts the roller pressing or passing mechanism, i.e., the cutting-out side.

[0020] In this embodiment, the tab 30 adopts an asymmetrical streamlined shape resembling a sports car. This design is not for aesthetic purposes, but rather to meet the stress distribution requirements of fluid mechanics and materials mechanics. Specifically, the first side edge 10 of each tab 30 smoothly transitions to the edge at the connection with the current collector, forming a first root fillet, and the second side edge 20 smoothly transitions to the edge at the connection with the current collector, forming a second root fillet. To effectively disperse the stress concentration experienced by the root of the tab 30 during high-speed belt travel, and especially to prevent the tab 30 from abruptly folding when entering the float roller, the radius of the first root fillet in this embodiment is designed to be larger than the radius of the second root fillet.

[0021] The first side edge 10 is inclined towards the central axis of the tab 30 to form a first inclination angle, while the second side edge 20 is inclined towards the central axis of the tab 30 to form a second inclination angle. The inclination angle referred to here is the angle between the tangent of the side edge and the straight line of the current collector edge. In this embodiment, the angle of the first inclination angle relative to the current collector edge is smaller than the angle of the second inclination angle relative to the current collector edge. This asymmetrical design, with a gentler front and steeper rear, allows the first side edge 10 of the tab 30 to engage at a gentler angle when it cuts into the roller body at high speed with the electrode sheet, thereby significantly reducing the impact resistance experienced by the tab 30 and eliminating the risk of crescent-shaped creases at the root commonly found in traditional symmetrical rectangular tabs 30.

[0022] The specific dimensions of the electrode tab 30 in the main electrode tab assembly were precisely defined. The angle value of the first tilt angle is... ,in This angle range, verified through extensive experiments, represents the optimal range for balancing the current-carrying area and anti-bending performance of the balance tab 30. Correspondingly, the angle value of the second tilt angle is... ,in Regarding the dimensions of the root fillet, the radius of the first root fillet, i.e., the fillet radius on the tangent side, is... ,in This larger fillet radius provides a wide stress relief zone; while the fillet radius of the second root fillet, i.e., the cut-out side, is... ,in Compared to the symmetrical 5mm rounded corners commonly used in existing technologies, this embodiment significantly increases the root rounded corner size and achieves a differentiated distribution, effectively improving the tear resistance and fatigue resistance of the root of the tab 30.

[0023] The top structure of the tab 30 also employs an optimized design. The tab 30 has a top edge connecting the first side edge 10 and the second side edge 20, which is substantially parallel to the edge of the current collector. The edge where the first side edge 10 connects to the top edge forms a first top fillet, and the edge where the second side edge 20 connects to the top edge forms a second top fillet. To accommodate the tilt angle of the side edges and further optimize the current density distribution, the radius of the first top fillet is... ,in The radius of the second top rounded corner is ,in This asymmetrical arrangement of the top rounded corners, combined with the root rounded corners and the side edge inclination angles, together form the asymmetrical streamlined profile of the tab 30.

[0024] In terms of macroscopic dimensions, the root width of a single electrode 30 at its connection with the current collector, i.e., the bottom width of the electrode 30, in the main electrode tab assembly of this electrode sheet is [missing information]. ,in The width of the top edge of the tab 30 is... ,in The height of the tab 30, i.e., the vertical distance from the edge of the current collector to the top edge of the tab 30, is... ,in Furthermore, the distance between the base of the tab 30 and the edge of the active material coating area on the current collector is set to 2mm, with an allowable tolerance range of ±0.5mm. This blank area ensures that the coating is not damaged during the cutting of the tab 30 and subsequent welding processes. This set of dimensional parameters ensures that the tab 30 has sufficient current-carrying cross-sectional area to meet the high-rate charging and discharging requirements of large-capacity square aluminum-cased cells such as 133Ah, while effectively controlling the temperature rise of the tab 30 under high current operation.

[0025] To accommodate the changes in tension and curvature caused by the continuous variation in electrode diameter during the winding process, the electrode tabs 30 in this embodiment are divided into three functional groups along the length of the current collector: the main tab group, the electrode entry tab group located at the electrode inlet end, and the electrode termination tab group located at the electrode termination end. This partitioned design fully considers the characteristics of the electrode curvature being extremely high at the winding needle during the initial winding stage and the tension release of the electrode during the final winding stage.

[0026] The electrode lug assembly consists of four lugs arranged sequentially along the direction away from the feed end. The root width of these four lugs 30 is designed to increase progressively, successively being... ( ), ( ), ( )and ( ), until transitioning to the main electrode assembly This gradually wide design allows the tab 30 to better adapt to the small curvature radius of the winding needle during the initial winding stage, avoiding excessive compression or wrinkling at the winding center due to the tab 30 being too wide.

[0027] The final electrode assembly consists of six electrodes arranged sequentially along the direction closest to the final end. The root width of these six electrodes (30mm) adopts a decreasing design, successively as follows: ( ), ( ), ( ), ( ), ( )and ( Furthermore, to prevent poor contact or spatial interference between the outermost tab 30 and the housing after winding and installation, the height of the last two tabs 30 in the finishing tab assembly has been specially adjusted, as described previously. Reduced to ,in This height-level clearance design improves the safety and assembly yield of the battery cells after they are installed in the casing.

[0028] The aforementioned tab 30 morphology is formed using a high-precision laser cutting process. Laser cutting not only precisely cuts the complex asymmetric curves and gradient dimensions, but also minimizes the heat-affected zone and eliminates burrs, further reducing the risk of the tab 30 puncturing the separator. By adopting the electrode structure described in this embodiment, in actual production verification, the tab 30 folding rate was significantly reduced from the original 1.75% to 0.02%, greatly improving the battery manufacturing yield and long-term operational reliability.

[0029] Example 2 This embodiment further illustrates the specific construction of a battery incorporating the aforementioned electrode structure. The battery is specifically designed as a square aluminum-cased lithium iron phosphate battery with a nominal capacity of 133Ah. The core components of the battery include a wound cell, which is manufactured by a winding process using a positive electrode, a negative electrode, and a separator between them. The positive electrode employs the electrode structure with asymmetrical sports car-shaped tabs 30 detailed in Embodiment 1.

[0030] During the battery winding process, the electrode sheets pass through tension control mechanisms such as floating rollers when traveling at high speed. Traditional tab 30 structures are typically symmetrical rectangular or trapezoidal. During high-speed entry and exit from the guide roller contact surface, the root of the tab 30 is prone to folding due to sudden stress changes, and subsequently being drawn into the cell, causing a serious internal short circuit hazard. The electrode structure used in this embodiment solves this problem through a specific asymmetrical design.

[0031] Specifically, when the electrode moves along the feed direction, the first side edge 10 of the tab 30 serves as the cutting side, at a first tilt angle. ( The gentler inclination angle and radius are ( The large-sized first root with rounded corners contacts the guide roller or cutter component. This design makes the stress transition of the tab 30 extremely smooth at the moment of contact, like the streamlined front of a sports car cutting through the wind, effectively avoiding the crescent-shaped bending of the root of the tab 30 due to excessive contact resistance. Subsequently, the second side edge 20 of the tab 30 serves as the cutting side, with a second tilt angle. ( The steeper inclination angle and radius are ( The second root rounded corner of the electrode detaches from the contact area, ensuring the structural rigidity and rebound stability of the electrode 30 during rapid detachment.

[0032] Furthermore, during the battery assembly process, after the battery cells are wound, they need to be installed into a square aluminum casing. At this time, the terminal tabs located at the end of the electrode assembly play a crucial role. Because the outer diameter of the wound battery cell is the largest, the outer tab 30 is closest to the casing cover. In this embodiment, the height of the last two tabs 30 of the terminal tab assembly is intentionally reduced to... ( Compared to the main electrode assembly ( The height difference provides necessary safety clearance for the welding of the top cover and the explosion-proof valve structure, preventing assembly interference or insulation film puncture risks caused by excessively high tabs 30. Meanwhile, the width of the tail tab assembly is from... ( Gradually decrease to ( The design also allows the outer tab 30 to naturally close during the bus welding process, avoiding edge overflow after the multi-layer tab 30 is stacked, and further improving the energy density and assembly yield of the battery.

[0033] Example 3 This embodiment focuses on the optimization of the manufacturing process of the above-mentioned electrode structure and the significant technical effects it brings, especially the improvement made to address the problem of high folding rate of the tab 30 in the prior art.

[0034] In existing conventional manufacturing processes, tabs of the same type and specification typically employ a symmetrical design, with a root width generally of 53mm and an allowable tolerance of ±0.5mm; the side edge inclination angle is usually uniformly 84.8°. The top corner radius is 8mm, and the root corner radius is 5mm. In actual large-scale mass production data, the folding rate of this traditionally designed tab 30 during the slitting and rolling process can reach up to 1.75%, which is a significant loss for power battery manufacturing that pursues ultimate safety and cost control.

[0035] This embodiment comprehensively innovates the above parameters through the laser cutting process of tab 30. First, by setting the laser cutting program, the shape of tab 30 is reconstructed into an asymmetric racing car shape in the feeding direction. In controlling the laser cutting path, the root width of tab 30 is increased to... ( This increases the load-bearing width at the base of the 30-pole lug, thereby improving the overall torsional stiffness.

[0036] Meanwhile, the trajectory parameters of the laser cutting were finely adjusted: the cutting angle on the infeed side was set to... ( ),Cooperate ( The rounded corner trajectory; the cutting angle of the cut-out side is set to... ( ),Cooperate ( The rounded corner trajectory of the top corner is also adjusted accordingly to the cutting side. ( ) and the cut side ( The asymmetric combination of these parameters is not an arbitrary numerical adjustment, but rather based on the dynamic analysis of the folding trajectory of the floating rollers during the conveyor belt operation.

[0037] Through the implementation of the above process parameters, in the mass production verification of 133Ah lithium iron phosphate cells, the folding rate of tab 30 achieved a qualitative leap, significantly reducing from the original 1.75% to 0.02%. This result indicates that the electrode structure and its manufacturing parameters described in this embodiment greatly improve the forward and reverse folding phenomenon of tab 30 during the tape-carrying process, eliminate the hidden danger of tab 30 folding into the core, thereby effectively ensuring the consistency of the cell's electrical performance, reducing the safety risks of self-discharge and internal short circuits, and meeting the stringent requirements of automotive-grade power batteries for high quality and high safety.

[0038] This application also discloses a battery, including the battery electrode as described in any of the above.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application. Content not described in detail in this application belongs to the prior art known to those skilled in the art.

Claims

1. A battery electrode, characterized in that, The device includes a current collector and a plurality of tabs spaced apart along the length of the current collector. Each tab has a first side edge and a second side edge arranged opposite to each other along the length of the current collector. The edge where the first side edge connects with the current collector forms a first root fillet, and the edge where the second side edge connects with the current collector forms a second root fillet, wherein the radius of the first root fillet is greater than the radius of the second root fillet. The first side edge is inclined toward the central axis of the tab to form a first tilt angle, and the second side edge is inclined toward the central axis of the tab to form a second tilt angle, wherein the angle value of the first tilt angle relative to the edge of the current collector is less than the angle value of the second tilt angle relative to the edge of the current collector.

2. The battery electrode according to claim 1, characterized in that, The angle value of the first tilt angle is , The angle value of the second tilt angle is , .

3. The battery electrode according to claim 2, characterized in that, The radius of the first root fillet is , The radius of the second root fillet is , .

4. The battery electrode according to claim 3, characterized in that, The electrode tab also has a top edge connecting the first side edge and the second side edge; the edge where the first side edge connects to the top edge forms a first top rounded corner, and the edge where the second side edge connects to the top edge forms a second top rounded corner; the radius of the first top rounded corner is... , The radius of the second top rounded corner is , .

5. The battery electrode according to claim 4, characterized in that, The plurality of tabs includes a main tab group distributed along the length of the current collector, an inlet tab group located at the electrode inlet end, and a tail tab group located at the electrode outlet end; the root width of the tab in the main tab group at the connection point with the current collector is [missing information]. , .

6. The battery electrode according to claim 5, characterized in that, The width of the top edge of the electrode in the main electrode assembly is , The height of the electrode in the main electrode assembly is... , .

7. The battery electrode according to claim 5, characterized in that, The tab assembly consists of four tabs arranged sequentially along the direction away from the feed end, and the root widths of the four tabs are respectively: , , , , , and , .

8. The battery electrode according to claim 5, characterized in that, The terminal electrode assembly consists of six electrodes arranged sequentially along the direction close to the terminal end, with the root widths of the six electrodes being sequentially as follows: , , , , , , , , , and , .

9. The battery electrode according to claim 6, characterized in that, The height of the last two electrodes in the tail electrode assembly is: , .

10. A battery, characterized in that, Including the battery electrode as described in any one of claims 1-9.

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