Battery cell and battery

Abstract

The utility model provides a battery cell and a battery, the battery cell comprises a first pole piece, a second pole piece and a diaphragm, the diaphragm is arranged between the first pole piece and the second pole piece, and the battery cell is formed by winding after the first pole piece, the diaphragm and the second pole piece are laminated; the first pole piece comprises a first end and a second end, the first end is a winding starting point of the first pole piece, and the second end is a winding ending point of the first pole piece; the first pole piece comprises a current collector and an active substance, the current collector is provided with a first surface and a second surface which are arranged along the lamination direction, the active substance is arranged on the first surface and the second surface, the tail end of the current collector corresponds to the second end of the first pole piece, the tail end of the current collector is provided with a third surface, and the third surface is arranged on the second surface. The third surface faces the winding direction; a first chamfer is arranged at the joint of the third face and the first face, and a second chamfer is arranged at the joint of the third face and the second face. And the problem of short circuit of the battery cell can be effectively avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy, and in particular to a battery cell and a battery. Background Art

[0002] In modern soft-pack battery technology, cylindrical cells typically use a copper foil tail structure. This not only reduces the use of separators during production, improving internal cell space utilization, and reducing the internal resistance of lithium-ion batteries during subsequent use, but also increases the capacity of lithium-ion batteries. However, due to the expansion of the negative electrode after charging, internal stress, and burrs and steps on the cathode sheet, the negative electrode copper foil is prone to breaking at the end of the cathode sheet, causing a short circuit within the battery. The negative electrode expands after charging, increasing stress within the cell. This makes it more likely that the cathode sheet will break, which can damage the interior of the cell and cause a short circuit. Furthermore, if barbs form on the cathode sheet after the internal stress increases, they are more likely to pierce the separator, causing a short circuit within the cell. The electrode sheets are typically cut during manufacturing, and burrs are easily formed at the ends of the electrode sheets during the cutting process. Therefore, there is a need for a battery cell that can effectively prevent internal short circuits in the battery. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a battery cell that can effectively avoid the problem of battery cell short circuit.

[0004] The utility model also provides a battery.

[0005] According to an embodiment of the first aspect of the present invention, a battery cell includes a first electrode sheet, a second electrode sheet and a diaphragm, the diaphragm is arranged between the first electrode sheet and the second electrode sheet, and the battery cell is formed by stacking and winding the first electrode sheet, the diaphragm and the second electrode sheet; the first electrode sheet includes a first end and a second end, the first end is the winding starting point of the first electrode sheet, and the second end is the winding end point of the first electrode sheet; the first electrode sheet includes a current collector and an active material, the current collector is provided with a first surface and a second surface along the stacking direction, the active material is provided on the first surface and the second surface, the tail end of the current collector corresponds to the second end of the first electrode sheet, and the tail end of the current collector is provided with a third surface, and the third surface faces the winding direction; the connection between the third surface and the first surface is provided with a first chamfer, and the connection between the third surface and the second surface is provided with a second chamfer.

[0006] According to an embodiment of the first aspect of the present invention, a battery cell has at least the following beneficial effects: by providing a first chamfer and a second chamfer at the end of the first pole piece, the stress concentrated at the end of the first pole piece is dispersed by the chamfer, thereby making the end of the first pole piece less susceptible to cracking. At the same time, the first chamfer and the second chamfer also reduce burrs at the end of the first pole piece. As a result, the diaphragm in the battery cell is less likely to be punctured, thereby reducing the possibility of short circuits within the battery cell.

[0007] According to some embodiments of the present invention, the first chamfer and the second chamfer are rounded corners.

[0008] According to some embodiments of the present invention, the rounded corners are formed by extrusion.

[0009] According to some embodiments of the present invention, the current collector on the first pole piece is aluminum foil.

[0010] According to some embodiments of the present invention, the first electrode is a positive electrode.

[0011] According to some embodiments of the present invention, after the first pole piece, the diaphragm and the second pole piece are wound to form a battery core, the second pole piece covers the second end of the first pole piece.

[0012] According to some embodiments of the present invention, a finishing glue is provided at one end of the second pole piece close to the winding end point, so that the one end of the second pole piece close to the winding end point is fixed on the second pole piece.

[0013] According to some embodiments of the present invention, the head end of the current collector corresponds to the first end of the first pole piece, the head end of the current collector is provided with a fourth surface, the fourth surface is facing the winding direction, the connection between the fourth surface and the first surface is provided with a third chamfer, and the connection between the fourth surface and the second surface is provided with a fourth chamfer.

[0014] According to some embodiments of the present invention, after the first pole piece, the diaphragm and the second pole piece are stacked, they are wound with the second pole piece as the inner side to form a battery cell, and one end of the second pole piece close to the winding starting point is wound and wrapped inside the second pole piece.

[0015] A battery according to an embodiment of the second aspect of the present invention includes the battery cell described in any one of the above embodiments.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a schematic structural diagram of the battery cell of the present utility model;

[0018] Figure 2 It is a partial enlarged schematic diagram of the battery cell of the present utility model;

[0019] Figure 3 This is a schematic structural diagram of a die for extruding rounded corners in a battery cell of the present invention.

[0020] Figure Number:

[0021] 1. First pole piece; 11. First surface; 12. Second surface; 13. Third surface; 14. Current collector; 15. Tail end; 16. First chamfer; 17. Second chamfer; 18. First end; 19. Second end; 2. Second pole piece; 3. Diaphragm; 41. First part; 42. Second part; 43. Extrusion surface; 44. Mating surface. DETAILED DESCRIPTION

[0022] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0023] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] In the description of this utility model, "a plurality" means more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0025] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0026] In modern technology, batteries, as key components for energy storage and supply, are widely used in various electronic devices, vehicles, and energy storage systems. However, a short circuit at one end of a battery can pose a variety of hazards. When a battery short circuits, the current flows abnormally, potentially damaging the battery's internal structure, such as deformation, corrosion, or melting of electrode materials, and evaporation or leakage of the electrolyte. Short circuits accelerate the imbalance of chemical reactions within the battery, leading to decreased battery performance and shortening its service life. For certain types of batteries, such as lithium-ion batteries, short circuits can trigger thermal runaway or explosion, generating large amounts of heat and gas, causing the battery to rupture, burn, or even explode. The excessive short-circuit current can subject circuit boards to stress beyond their design limits, causing them to burn and disrupting the proper operation of electronic equipment. The excessive current caused by a short circuit can damage the internal components of electronic equipment, reducing their performance and stability, and in severe cases, even causing device failure.

[0027] The manufacture of electrode sheets is a critical step in the lithium battery production process, directly impacting battery performance and quality. The main raw materials for electrode sheets include active materials (such as lithium cobalt oxide for the positive electrode and graphite for the negative electrode), binders (such as PVDF and SBR), and conductive agents (such as carbon black and carbon nanotubes). These materials must be mixed in specific proportions to produce a uniform and stable slurry. The active material, binder, and conductive agent are placed in a blender in specific proportions, and an appropriate amount of solvent (such as NMP) is added. High-speed stirring is performed. The stirring speed and duration must be controlled to ensure uniform dispersion of the slurry, free of bubbles and agglomerates. After stirring, the slurry is tested for viscosity, solids content, particle size distribution, and other indicators to ensure that the slurry meets quality requirements. The prepared slurry is evenly coated on the surface of a metal current collector (such as copper or aluminum foil). The coating process requires controlled coating speed, thickness, and uniformity to ensure electrode sheet quality. Common coating methods include blade coating, extrusion coating, and transfer coating. After coating, the electrode sheets are sent to a drying machine for drying to remove the solvent and form dry electrode sheets. During the drying process, parameters such as temperature, humidity, and air speed must be controlled to ensure uniform drying of the electrode sheets and to avoid defects such as cracks and bubbles. The dried electrode sheets are then compacted in a roller press to increase their density and strength. During the roller press, parameters such as pressure and speed must be controlled to ensure that the compaction meets the required compaction. The surface of the rolled electrode sheets should be flat and free of defects such as cracks and bubbles. The rolled electrode sheets are then cut according to the dimensions specified by the battery design. During the cutting process, parameters such as cutting speed and accuracy must be controlled to ensure that the electrode sheet size and shape meet the required specifications. The cut electrode sheets are also quality inspected to ensure that they are free of defects such as burrs and wavy edges. Quality inspection and control are required at every stage of the electrode manufacturing process. This includes quality inspection of raw materials, slurry, coating and drying processes, and electrode sheet quality inspection after rolling and cutting. Only through strict quality control can we ensure that the quality and performance of the electrode meet the requirements. During the slitting process, burrs are easily formed on the electrode.

[0028] Reference Figure 1 and Figure 2 A battery cell according to an embodiment of the first aspect of the present invention includes a first electrode sheet 1, a second electrode sheet 2, and a separator 3. The separator 3 is disposed between the first electrode sheet 1 and the second electrode sheet 2. The battery cell is formed by stacking the first electrode sheet 1, the separator 3, and the second electrode sheet 2 and then winding them. The first electrode sheet 1 includes a first end and a second end, the first end being the starting point of winding the first electrode sheet 1, and the second end being the end point of winding the first electrode sheet 1. When winding the battery cell, the first electrode sheet 1, the separator 3, and the second electrode sheet 2 are stacked in sequence. After stacking, the battery cell is wound along the length of the first electrode sheet 1 from the first end to the second end, thereby forming a cylindrical battery cell shape.

[0029] The first electrode sheet 1 includes a current collector 14 and active material. The current collector 14 is provided with a first surface 11 and a second surface 12 arranged along the stacking direction. The active material is disposed on the first surface 11 and the second surface 12. The tail end 15 of the current collector 14 corresponds to the second end of the first electrode sheet 1 and is provided with a third surface 13, which faces the winding direction. A first chamfer 16 is provided at the junction between the third surface 13 and the first surface 11, and a second chamfer 17 is provided at the junction between the third surface 13 and the second surface 12. The chamfers prevent excessive concentration of internal stress on the first electrode sheet 1 during the winding process, thereby reducing the risk of cracking the current collector 14 on the first electrode sheet 1. The chamfers can be formed by pressing, polishing, or casting. By chamfering the tail end 15 of the current collector 14, burrs formed during cutting are reduced, effectively preventing burrs from piercing the diaphragm 3 and causing short circuits. The chamfers can be configured in various ways, such as rounded corners and flat chamfers. After the first chamfer 16 and the second chamfer 17 are provided to reduce the burrs on the current collector 14 , the self-discharge phenomenon of the battery cell can also be effectively prevented.

[0030] Cell self-discharge refers to the phenomenon in which the internal charge of a cell spontaneously decreases or dissipates while the cell is in storage or unused. Burrs on the current collector 14 can exacerbate this phenomenon. Cell self-discharge causes a continuous loss of charge within the battery, which means the battery's effective capacity gradually decreases. Over time, if the self-discharge rate is too rapid, the battery's usable capacity will significantly decrease, affecting the device's usable time and the battery's overall lifespan. In a battery pack or battery pack, if the self-discharge performance of each cell is inconsistent, the remaining charge in each cell will vary significantly after long periods of storage or storage. This can cause cells with lower charge levels to be easily overcharged or over-discharged during series charging or discharging, affecting the performance and stability of the entire battery pack. In extreme cases, excessive self-discharge can cause excessive pressure inside the cell and even lead to safety issues. While this is relatively rare, it is still a risk that requires attention.

[0031] According to some embodiments of the present invention, the first chamfer 16 and the second chamfer 17 are rounded corners. Setting the chamfers as rounded corners not only better disperses the stress on the first pole piece 1, but also makes the end of the first pole piece 1 smoother, thereby reducing burrs on the tail end 15 of the current collector 14. Furthermore, the first chamfer 16 and the second chamfer 17 are configured as interconnected arc surfaces, so that the tail end 15 of the current collector 14 forms a 180° semicircular arc surface or an elliptical arc surface.

[0032] According to some embodiments of the present invention, the rounded corners are formed by extrusion. Extrusion can reduce burrs and make processing more convenient. Figure 3 Specifically, a mold is used to extrude the current collector 14 to form the first chamfer 16 and the second chamfer 17. The mold includes a first part 41 and a second part 42, and an extrusion surface 43 and a matching surface 44 are respectively provided on the first part 41 and the second part 42. The extrusion surface 43 enables the first part 41 and the second part 42 to extrude the tail of the current collector 14 at the same time, and at this time the first part 41 and the second part 42 are close to each other. Moreover, when the first part 41 and the second part 42 are close to each other and the matching surfaces 44 on the first part 41 and the second part 42 are in contact with each other, the extrusion is completed. The extrusion surface 43 is further set to a plane and an arc surface, and the arc surface extrude the current collector 14 to form a fillet, and the plane abuts against the first surface 11 and the second surface 12 on the current collector 14, so that the connection between the fillet and the first surface 11 or the second surface 12 is smoother.

[0033] According to some embodiments of the present invention, the first electrode sheet 1 is a positive electrode sheet, and the current collector 14 on the first electrode sheet 1 is aluminum foil. The selection of copper and aluminum foil for the electrode sheet is primarily based on material properties, battery performance requirements, and cost considerations. Copper foil, as the negative electrode current collector 14, requires good electrical conductivity to ensure smooth current transmission within the battery. Furthermore, copper foil is relatively soft, making it suitable for manufacturing battery electrode sheets, particularly during winding and lamination processes, where it can reduce the risk of brittle fracture during processing. With the advancement of lithium battery technology, the thickness of copper foil has gradually decreased to reduce battery volume and weight. Currently, the thickness of negative electrode copper foil has been reduced from 12μm to 6μm or even thinner to meet the demand for lightweight batteries. Aluminum foil also has good electrical conductivity and is relatively soft, making it suitable for manufacturing battery positive electrode sheets. The conductivity of aluminum foil helps effectively transmit the electrical energy generated by the positive electrode material to the external circuit. Aluminum forms a dense oxide film in air, which protects the aluminum surface and prevents further oxidation. At the same time, in the electrolyte, this oxide film can also play a certain protective role and improve the safety of the battery. The positive electrode potential of the lithium battery is relatively high, and the use of aluminum foil as the positive electrode current collector 14 can maintain stability at high potentials. In contrast, copper foil is easily oxidized at high potentials and is therefore not suitable for use as the positive electrode current collector 14. The thickness of the positive electrode aluminum foil is generally between 5-20μm, and the specific thickness depends on the type of battery and operating conditions. Thinner aluminum foil can reduce resistance and improve battery performance, but too thin aluminum foil may increase the risk of battery pinholes or tears, so it needs to be selected according to actual conditions.

[0034] Therefore, to improve battery performance, the positive electrode sheet is typically aluminum foil, and the negative electrode sheet is typically copper foil. Furthermore, the aluminum foil needs to be thicker than the copper foil, and a thicker thickness makes it easier to create the first chamfer 16 and the second chamfer 17. Therefore, the current collector 14 in the first electrode sheet 1 is aluminum foil, and the first electrode sheet 1 is configured as the positive electrode sheet.

[0035] According to some embodiments of the present invention, after the first electrode 1, diaphragm 3, and second electrode 2 are wound to form a battery cell, the second electrode 2 covers the second end of the first electrode 1. Because the second end of the first electrode 1 is provided with a first chamfer 16 and a second chamfer 17, the second end of the first electrode 1 is less likely to puncture the diaphragm 3. When the first end of the first electrode 1 is separated by a layer of diaphragm 3 and pressed against the second electrode 2, the interior of the battery cell is safer and less likely to cause a short circuit. However, if the end of the second electrode 2 near the winding end is separated by a layer of diaphragm 3 and pressed against the first electrode 1, it is more likely to puncture the diaphragm 3, causing the burr on the end of the second electrode 2 near the winding end to puncture the diaphragm 3 and cause a short circuit. Therefore, the second electrode 2 covers the second end of the first electrode 1, that is, the end of the second electrode 2 near the winding end extends beyond the second end of the first electrode 1. At this time, the second end of the first electrode 1 is wrapped from both sides by two layers of the second electrode 2 through the diaphragm 3. The end of the second pole piece 2 near the winding end is connected to the second pole piece 2 through a separator 3. If the battery cell is squeezed and a burr on the end of the second pole piece 2 near the winding end pierces the separator 3, it will only connect to the second pole piece 2 itself, and a short circuit will not occur. This arrangement eliminates the need to use thick tape at the end of the battery cell to prevent burrs from piercing the separator 3. This can increase the energy density of the battery cell.

[0036] According to some embodiments of the present invention, a finishing glue is provided at one end of the second pole piece 2 near the winding end point, so that the end of the second pole piece 2 near the winding end point is fixed to the second pole piece 2. The finishing glue fixes the end of the second pole piece 2 near the winding end point, thereby making the structure of the entire battery cell more stable.

[0037] According to some embodiments of the present invention, the head end of the current collector 14 corresponds to the first end of the first pole piece 1. The head end of the current collector 14 is provided with a fourth surface, which faces the winding direction. The connection between the fourth surface and the first surface 11 is provided with a third chamfer, and the connection between the fourth surface and the second surface 12 is provided with a fourth chamfer. The head end of the current collector 14 corresponds to the starting point of the cell winding. To prevent burrs at the head end of the current collector 14 from puncturing the diaphragm 3 and causing a short circuit, the third and fourth chamfers are provided at the head end of the current collector 14. This not only reduces burrs but also reduces the risk of rupture of the current collector 14.

[0038] According to some embodiments of the present invention, after the first electrode sheet 1, separator 3, and second electrode sheet 2 are stacked, they are wound with the second electrode sheet 2 as the inner side to form a battery cell. The end of the second electrode sheet 2 near the winding starting point is wound and wrapped inside the second electrode sheet 2. By winding and wrapping the end of the second electrode sheet 2 near the winding starting point inside the second electrode sheet 2, even if a burr appears on the end of the second electrode sheet 2 near the winding starting point, it will not connect to the first electrode sheet 1, and a short circuit will not occur. This further enhances the safety of the battery cell.

[0039] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A battery cell, characterized in that: The battery cell comprises a first pole piece, a second pole piece and a diaphragm, wherein the diaphragm is arranged between the first pole piece and the second pole piece, and the battery cell is formed by stacking the first pole piece, the diaphragm and the second pole piece and then winding them; the first pole piece comprises a first end and a second end, the first end is the starting point of the winding of the first pole piece, and the second end is the end point of the winding of the first pole piece; The first pole piece includes a current collector and an active material. The current collector is provided with a first surface and a second surface along a stacking direction. The active material is provided on the first surface and the second surface. The tail end of the current collector corresponds to the second end of the first pole piece. The tail end of the current collector is provided with a third surface, and the third surface faces the winding direction. A first chamfer is provided at a connection between the third surface and the first surface, and a second chamfer is provided at a connection between the third surface and the second surface.

2. A battery cell according to claim 1, characterized in that: The first chamfer and the second chamfer are rounded corners.

3. A battery cell according to claim 2, characterized in that: The rounded corners are formed by extrusion.

4. A battery cell according to claim 3, characterized in that: The current collector on the first pole piece is aluminum foil.

5. The battery cell according to claim 4, characterized in that: The first electrode is a positive electrode.

6. The battery cell according to claim 1, characterized in that: After the first pole piece, the diaphragm and the second pole piece are wound to form a battery core, the second pole piece covers the second end of the first pole piece.

7. The battery cell according to claim 6, characterized in that: A finishing glue is provided on one end of the second pole piece close to the winding end point, so that the end of the second pole piece close to the winding end point is fixed on the second pole piece.

8. The battery cell according to claim 1, characterized in that: The head end of the current collector corresponds to the first end of the first pole piece. The head end of the current collector is provided with a fourth surface, and the fourth surface faces the winding direction. The connection between the fourth surface and the first surface is provided with a third chamfer, and the connection between the fourth surface and the second surface is provided with a fourth chamfer.

9. The battery cell according to claim 7, characterized in that: After the first pole piece, the diaphragm and the second pole piece are stacked, they are wound with the second pole piece as the inner side to form a battery cell, and one end of the second pole piece close to the winding starting point is wound and wrapped inside the second pole piece.

10. A battery, characterized in that: The invention comprises the battery cell described in any one of claims 1 to 9.

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