Battery cell, cylindrical battery, and electric device

Abstract

The utility model provides a kind of electric core, cylindrical battery and electric equipment, the electric core is wound to form cylindrical shape by pole piece and diaphragm, the pole piece includes current collector and active material layer, active material layer is at least partially arranged in the thickness direction of current collector at least one side, active material layer is equipped with multiple recessed structures on the surface away from current collector, the area proportion of recessed structure gradually decreases in the direction from the winding starting end to the terminal end of pole piece, the electric core can improve the infiltration effect of electrolyte to the inner ring pole piece of cylindrical battery.

Description

Technical Field

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

[0002] In related technologies, with the increasing demand for high capacity in cylindrical batteries, the height of the electrode plates and the diameter of the cell in cylindrical batteries have also increased. When electrolyte is injected into the cell of a cylindrical battery to wet the electrode plates, the electrode plates near the inner ring are more tightly closed, making it more difficult for the electrolyte to wet the inner ring electrode plates. The electrode plates that are not wetted by electrolyte will develop black spots during the use of the cylindrical battery, which will affect the charge and discharge performance of the cylindrical battery and reduce the cycle life of the cylindrical battery. Utility Model Content

[0003] In view of the above-mentioned technical problems, the present invention provides an electrode sheet and a battery pack to improve the wetting effect of the electrolyte on the inner electrode sheet of the cylindrical battery, so as to at least partially solve the above-mentioned technical problems.

[0004] In a first aspect, the present invention provides a battery cell, wherein the battery cell is formed into a cylindrical shape by winding an electrode and a separator, the electrode comprising: a current collector; an active material layer, which is at least partially disposed on at least one side of the current collector in the thickness direction, the active material layer having a plurality of recessed structures on the surface opposite to the current collector, and the area ratio of the recessed structures gradually decreasing in the direction from the starting end to the ending end of the winding of the electrode.

[0005] Optionally, in the first turn of the electrode, the area of ​​the recessed structure accounts for 45% to 60% of the total area of ​​the current turn; in the last turn of the electrode, the area of ​​the recessed structure accounts for 20% to 35% of the total area of ​​the current turn.

[0006] Optionally, the area ratio of the recessed structure in the first turn of the electrode winding and the area ratio of the recessed structure in the last turn of the electrode winding are the area difference, and the product of the area difference and the diameter of the cell satisfies 1 to 40.

[0007] Optionally, the plurality of said recessed structures are arranged at intervals along the length of the active material layer, or the plurality of said recessed structures are arranged in an array on the active material layer.

[0008] Optionally, the recessed structure is constructed as a circular groove, and the number of the circular grooves is multiple and arranged at intervals on the surface of the active material layer.

[0009] Optionally, the circular groove is recessed inward along the thickness direction of the active material layer, or the circular groove penetrates the active material layer along the thickness direction of the active material layer.

[0010] Optionally, the distance between the center of the recessed structure closest to the edge of the electrode and the end face of the electrode ranges from 10 to 150 μm.

[0011] Optionally, the projected area of ​​the recessed structure toward the active material layer is A, and in the plurality of recessed structures, A gradually increases along the direction from both ends to the middle of the cell.

[0012] Secondly, this utility model provides a cylindrical battery, including the cell described in any of the above-mentioned optional solutions.

[0013] Thirdly, this utility model provides an electrical device, including the cylindrical battery described in the above-mentioned optional solution.

[0014] Through the above-described technical solution, namely the battery cell provided by this utility model, after the battery cell is formed by winding the electrode sheets and the separator, the degree of electrolyte wetting of the inner electrode sheets can be improved by using a concave structure with a varying area ratio along the starting and ending points of the electrode winding. This can be understood as the degree of electrode sheet tightening from the starting to the ending point of the electrode winding being a process of decreasing tightness; that is, the closer the electrode sheet is to the center, the tighter the tightening, making it more difficult for the electrolyte to enter and wet the inner electrode sheet, while the closer the electrode sheet is to the outer edge, the tighter the tightening... The looser the electrolyte, the easier it is for it to enter the electrode and wet the outer ring of the electrode. Therefore, by setting a recessed structure with a higher area ratio at the starting end of the electrode winding, that is, the inner ring of the electrode, when the cell is wetted by electrolyte, more electrolyte can flow into the recessed structure of the inner ring of the electrode and be stored temporarily. This can improve the degree of wettability of the inner ring of the electrode, thereby reducing or avoiding the phenomenon of black spots in cylindrical batteries during use, improving the charge and discharge performance of cylindrical batteries, and also increasing the cycle life of cylindrical batteries. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram showing the cooperation between the current collector and the active material layer in the deployed state in an exemplary embodiment of this utility model.

[0017] Figure 2 This is a schematic diagram illustrating another arrangement of the current collector and the active material layer in the deployed state, as provided in an exemplary embodiment of this utility model.

[0018] Figure 3 This is a schematic diagram of a battery cell in a wound state provided in an exemplary embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram illustrating another method of the battery cell in a wound state provided in an exemplary embodiment of this utility model;

[0020] Figure 5 This is a schematic diagram of the recessed structure arranged on the surface of the active material layer in an exemplary embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Current collector;

[0023] 2. Active material layer; 210. Depression structure;

[0024] D. Diameter. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] In related technologies, with the increasing demand for high capacity in cylindrical batteries, the height of the electrode plates and the diameter of the cell in cylindrical batteries have also increased. When filling the cylindrical battery with electrolyte to wet the electrode plates, the electrode plates near the inner ring are more tightly closed, making it more difficult for the electrolyte to wet the inner ring electrode plates. The electrode plates that are not wetted by electrolyte will develop black spots during the use of the cylindrical battery, which will affect the charge and discharge performance of the cylindrical battery and reduce the cycle life of the cylindrical battery.

[0027] In view of the above-mentioned technical problems, the first aspect of this utility model provides a battery cell, with reference to... Figures 1 to 5 As shown, the battery cell can be formed into a cylindrical shape by winding an electrode and a separator. The electrode includes a current collector 1 and an active material layer 2. Specifically, the active material layer 2 is at least partially disposed on at least one side of the current collector 1 in the thickness direction. The active material layer 2 has a plurality of recessed structures 210 on the surface away from the current collector 1. The area ratio of the recessed structures 210 gradually decreases in the direction from the starting end to the ending end of the winding.

[0028] Through the above technical solution, namely the battery cell provided by this utility model, after the battery cell is formed by winding the electrode sheets and the separator, the degree of electrolyte wetting of the inner electrode sheets can be improved by using the recessed structure 210 with a varying area ratio from the starting end to the ending end of the electrode winding. This can be understood as the degree of electrode sheet tightening from the starting end to the ending end of the electrode winding being a process of decreasing tightness. Specifically, the closer the electrode sheet is to the center, the tighter the tightening, making it more difficult for the electrolyte to enter and wet the inner electrode sheet; the closer the electrode sheet is to the outer edge, the tighter the tightening. The looser the electrode, the easier it is for the electrolyte to enter the electrode and wet the outer ring electrode. Therefore, by setting a recessed structure 210 with a higher area ratio at the starting end of the electrode winding, that is, the inner ring of the electrode, when the cell is wetted by the electrolyte, more electrolyte can flow into the recessed structure 210 of the inner ring of the electrode and be stored temporarily. This can improve the degree of wettability of the inner ring of the electrode, thereby reducing or avoiding the phenomenon of black spots in cylindrical batteries during use, improving the charge and discharge performance of cylindrical batteries, and also increasing the cycle life of cylindrical batteries.

[0029] It should be noted that in the above specific embodiments, the current collector 1 can be understood as the positive or negative electrode of the battery, and the active material layer 2 can be understood as any suitable material disposed on the surface of the current collector 1 and having conductive function, so as to realize the charging and discharging process of the battery. In this embodiment, the current collector 1 of the positive electrode can be, for example, aluminum foil, aluminum alloy foil, or composite current collector (e.g., aluminum-carbon composite current collector), etc. This embodiment does not make specific limitations on this. Correspondingly, the specific material of the active material layer 2 connected to the current collector 1 of the positive electrode can include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, or lithium titanate, etc., or at least one of non-metallic elements such as fluorine, phosphorus, boron, chlorine, silicon, or sulfur. The appropriate material can be selected according to the actual situation.

[0030] Correspondingly, the current collector 1 of the negative electrode can be made of copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, or copper foam; or it can be made of composite current collectors such as lithium copper composite current collector, carbon copper composite current collector, nickel copper composite current collector, or titanium copper composite current collector. Correspondingly, the specific material of the active material layer 2 connected to the current collector 1 of the negative electrode can include at least one of natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, and silicon-carbon composite. The appropriate material can be selected according to the actual situation. Since the technology of using the above materials to apply to the current collector 1 and the active material layer 2 in the battery field is already very mature, this embodiment will not elaborate further.

[0031] It should be further explained that, in the above embodiments, the area ratio of the recessed structure 210 of the electrode gradually decreases from the starting end to the ending end of the winding. This can be understood as: the starting end of the electrode winding can be... Figure 3 The position 'a' in the text is also... Figure 5 The end point of the electrode winding can be located on the left side of the center. Figure 3 The d position in the middle is also... Figure 5 The position on the right side of the middle, combined with Figure 3 The degree of electrode winding and Figure 5 The change in the area ratio of the recessed structure 210 is clearly visible. The closer the electrode is to the outer ring, the smaller the area ratio of the recessed structure 210 on the corresponding active material layer 2. The closer the electrode is to the inner ring, the larger the area ratio of the recessed structure 210 on the corresponding active material layer 2. Thus, when wetted with electrolyte, more electrolyte can be stored through the denser recessed structure 210, thereby improving the wetting effect.

[0032] Taking the positive electrode as an example, the positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are released from the crystal lattice of the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (e.g., lithium ions in a lithium battery) are released from the negative electrode and intercalated into the crystal lattice of the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0033] Furthermore, the aforementioned positive electrode sheet generally includes a positive current collector and a positive active material layer. The positive active material layer can be coated on at least one surface of the positive current collector in the manner described above. The positive active material layer includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following materials: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination of two or more. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides (such as LiNi1 / 3Co1 / 3Mn1 / 3O2, LiNi0.5Co0.2Mn0.3O2, LiNi0.5Co0.25Mn0.25O2, LiNi0.6Co0.2Mn0.2O2, LiNi0.8Co0.1Mn0.1O2, lithium nickel cobalt aluminum oxides (such as LiNi0.85Co0.15Al0.05O2) and their modified compounds.

[0034] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0035] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0036] Conversely, taking the negative electrode as an example, during battery charging, active ions (such as Li) from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through the external circuit to maintain charge balance; during discharge, the active ions (such as Li) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the negative electrode through the external circuit to maintain charge balance; thus achieving energy storage and release.

[0037] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder.

[0038] The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-nitrogen composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0039] The electrolyte mentioned in the above embodiments can be understood as a liquid electrolyte that transports active ions. It is a liquid material that conducts ions while isolating electrons, and the electrolyte can be composed of chemical substances such as solvents, electrolyte salts, and additives; the solvent can be selected from carbonates, carboxylic acid esters, or ethers, etc.; the electrolyte salt can be selected from lithium salts, sodium salts, or zinc salts; the additives can be selected from vinylene carbonate, fluoroethylene carbonate, propylene sulfite, vinyl sulfite, etc.

[0040] The diaphragm mentioned in the above embodiments can be disposed between the positive and negative electrode plates to separate them and prevent short circuits. The diaphragm can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be provided on the surface of the diaphragm. The coating can be an inorganic coating and / or an organic coating. The inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0041] In some implementations, reference Figures 1 to 5 As shown, in the first turn of the electrode winding, the area of ​​the recessed structure 210 accounts for 45% to 60% of the total area of ​​the current turn; in the last turn of the electrode winding, the area of ​​the recessed structure 210 accounts for 20% to 35% of the total area of ​​the current turn.

[0042] Using the above method, the first turn of the electrode winding can be understood as the innermost turn of the electrode, and the last turn of the electrode winding can be understood as the outermost turn of the electrode. Figure 3 and Figure 4Two different winding methods for the electrode sheets are shown. Figure 3 This can be understood as the starting and ending ends of the electrode being located at the same position circumferentially after winding. Figure 3 This can be understood as follows: after the electrode is wound, the starting end and the ending end are located at different positions on the circumference of the electrode. Regardless of whether the starting end and the ending end are located at the same position on the circumference after the electrode is wound, the innermost ring of the electrode can represent... Figure 3 and Figure 4 Positions from a to b, and the outermost ring of the electrode can all represent this. Figure 3 and Figure 4 In the position from c to d, that is, in the electrode winding direction, a to b can be the innermost ring, and c to d can be the outermost ring. By limiting the area ratio of the recessed structure 210 from a to b to 45% to 60%, the wetting effect of the innermost ring of the electrode when immersed in electrolyte can be maximized. It also prevents the innermost ring of the electrode from having an excessively large area ratio of the recessed structure 210, which could lead to insufficient coating of active material. This also limits the lower limit of the amount of active material coated, thus ensuring the charge and discharge performance of the battery. Similarly, limiting the area ratio of the recessed structure 210 from c to d to 20% to 35% can also maximize the wetting effect of the outermost ring of the electrode when immersed in electrolyte. It also prevents the area ratio of the recessed structure 210 from being too large on the outer ring, which could lead to insufficient coating of active material. This also limits the lower limit of the amount of active material coated, thus ensuring the charge and discharge performance of the battery.

[0043] In some implementations, reference Figures 1 to 3 ,as well as Figure 5 As shown, the area ratio of the recessed structure 210 in the first turn of the electrode winding and the area ratio of the recessed structure 210 in the last turn of the electrode winding is the area difference, and the product of the area difference and the cell diameter D satisfies 1 to 40.

[0044] By limiting the product range of the area difference and the cell diameter D, the energy density and electrolyte wetting degree of the battery can be further optimized. This can be understood as... Figure 3In the example, the area ratio of the recessed structure 210 in the inner ring (a to b) can be represented by M1, and the area ratio of the recessed structure in the outer ring (c to d) can be represented by M2. That is, the value range of (M1-M2)*D needs to be within the range of 1 to 40. If (M1-M2)*D exceeds the maximum value of the above range, one situation is that the difference between M1 and M2 is too large, which means that the area ratio of the recessed structure 210 in the inner ring is too large. In this case, although the difficulty of wetting the inner ring is reduced, it is also easy to reduce the amount of active material coated, thereby reducing the overall battery energy density. Another situation is that the diameter D value becomes larger. Although the diameter D value will increase the overall energy density of the battery, the inner ring is more difficult to wet. Therefore, setting the value range of (M1-M2)*D between 1 and 40 can ensure the energy density of the battery itself and also ensure that the inner ring is easier to wet.

[0045] In some implementations, reference Figures 1 to 5 As shown, multiple recessed structures 210 are arranged at intervals along the length of the active material layer 2, or multiple recessed structures 210 are arranged in an array on the active material layer 2.

[0046] In this way, multiple recessed structures 210 are arranged at intervals or in an array on the active material layer 2, which can further improve the wetting degree of the electrolyte on the inner ring of the battery cell, i.e., it can be referred to Figure 5 As shown, in Figure 5 In the left-to-right direction of the diagram, that is, in the direction from the starting end to the ending end of the cell, multiple recessed structures 210 are arranged at intervals on the active material layer 2. In the direction from the starting end to the ending end, the distance between two adjacent recessed structures 210 gradually increases. It can be clearly seen that the area ratio of the recessed structure 210 decreases from the starting end to the ending end. That is, the area ratio of the recessed structure 210 closer to the inner ring is larger, and the area ratio of the recessed structure 210 closer to the outer ring is smaller. With this arrangement, the inner ring can be more easily wetted by the electrolyte.

[0047] It should be noted that the process of immersing the cylindrical battery in electrolyte as mentioned in the above embodiments actually involves immersing the cylindrical battery in an electrolyte bath after the battery cell is wound, i.e., the battery cell is wound into the shape described above. Figure 3 or Figure 4 After shaping, insert it into the cylindrical battery casing, then immerse one end of the cylindrical battery in the electrolyte bath. The electrolyte will gradually seep from one end of the cylindrical battery into the middle of the battery along its height. This can also be understood as the electrolyte flowing along... Figure 5The electrolyte is immersed in the middle of the cell from bottom to top in the middle of the height direction. The inner ring of the cell has a larger area ratio of concave structure 210. Even when it is rolled up tightly, there will be tiny gaps. The electrolyte can penetrate into the inner ring of the cell through these tiny gaps to wet the cell, thereby improving the electrolyte wetting effect and reducing or avoiding the occurrence of black spots during the subsequent use of cylindrical batteries.

[0048] Furthermore, in the above embodiments, the specific structure of the recessed structure 210 can be any suitable structure, as long as the recessed structure 210 can be recessed relative to the surface of the active material layer 2, for example, refer to Figure 1 , Figure 2 and Figure 5 As shown, in this embodiment, the recessed structure 210 can be constructed as a circular groove.

[0049] There can be multiple circular grooves, which are arranged at intervals on the surface of the active material layer 2.

[0050] In this way, the circular tank can maximize the retention volume of the electrolyte. That is, when the electrolyte flows through the circular tank, more electrolyte can be retained through the circular tank, thereby improving the wetting effect.

[0051] Alternatively, in other embodiments not shown in the figure, the recessed structure 210 can also be constructed as a groove of other structural forms, such as a rectangular groove or an irregular groove, which will not be elaborated on in this embodiment.

[0052] In some implementations, reference Figure 1 , Figure 2 as well as Figure 5 As shown, the circular groove is recessed inward along the thickness direction of the active material layer 2, or the circular groove penetrates the active material layer 2 along the thickness direction of the active material layer 2.

[0053] In the above manner, the circular groove can be recessed inward on the surface of the active material layer 2 or penetrate through the active material layer 2. When the circular groove penetrates through the active material layer 2, the wetting degree of the electrolyte can be further improved. However, since the circular groove on the active material layer 2 is usually made by rolling, manufacturing a through groove usually has a high processing difficulty. When the circular groove does not penetrate through the surface of the active material layer 2, that is, when it is only recessed inward, the processing difficulty of the circular groove can be reduced, but the wetting effect of the electrolyte will be further reduced. The appropriate arrangement of the circular groove can be selected according to the actual situation. This embodiment does not limit it too much.

[0054] Furthermore, combined Figure 1 and Figure 2As shown, the active material layer 2 can be arranged on one side of the current collector 1 or on both sides of the current collector 1. The appropriate arrangement method can be selected according to the actual situation and material requirements. This embodiment does not limit this too much.

[0055] In some implementations, reference Figure 5 As shown, the distance between the center of the recessed structure 210 closest to the edge of the electrode and the end face of the electrode ranges from 10 to 150 μm.

[0056] In this way, the distance range between the pattern center of the recessed structure 210 closest to the edge of the electrode and the end face of the electrode can be understood as: the pattern center of the recessed structure 210, and... Figure 5 The position of the battery cell in the upper or lower part of the image refers to its distance from one end of the cell. Figure 5 The indicated H1 distance, which is limited to 10-150μm, can prevent the recessed structure 210 from being too far from one end of the cell. This can also reduce or prevent the electrolyte from failing to enter the middle of the cell during the process of immersing from one end of the cell into the middle, thus reducing the difficulty of the electrolyte wetting the inside of the cell.

[0057] In some implementations, reference Figure 5 As shown, the projected area of ​​the recessed structure 210 toward the active material layer 2 is A. Among the multiple recessed structures 210, A gradually increases along the direction from both ends of the cell to the middle.

[0058] Through the above method, the projected areas of the multiple recessed structures 210 are different, which can be used as a reference. Figure 5 As shown, the recessed structure 210 closer to the center of the cell has a larger projected area, which allows more electrolyte to flow into the larger recessed structure 210, thus improving the wetting effect.

[0059] In a second aspect, this utility model provides a cylindrical battery that includes the battery cell mentioned in the above specific embodiments and has all the beneficial effects of the above specific embodiments. That is, the cylindrical battery using the above-mentioned wound battery cell also has the beneficial effect of improving the electrolyte wetting effect, thereby reducing or preventing black spots from appearing in the cylindrical battery during use, and also improving the charge and discharge performance and cycle life of the battery.

[0060] A third aspect of this utility model provides an electrical device that includes the cylindrical battery mentioned in the above-described specific embodiments and has all the beneficial effects of the above-described specific embodiments. The electrical device can be a smartphone, tablet computer, walkie-talkie, etc. in communication equipment, an LED lamp in lighting equipment, or any suitable electrically driven device such as an industrial robot, motor driver, frequency converter, or actuator in industrial control equipment.

[0061] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric cell, characterized by, The battery cell is formed into a cylindrical shape by winding electrodes and a separator, wherein the electrodes include: current collector(1); An active material layer (2) is at least partially disposed on at least one side of the current collector (1) in the thickness direction. The active material layer (2) has a plurality of recessed structures (210) on the surface away from the current collector (1). The area ratio of the recessed structures (210) gradually decreases in the direction from the starting end to the ending end of the winding of the electrode.

2. The electric cell of claim 1, wherein, In the first turn of the electrode, the area of ​​the recessed structure (210) accounts for 45% to 60% of the total area of ​​the current turn; In the last turn of the electrode, the area of ​​the recessed structure (210) accounts for 20% to 35% of the total area of ​​the current turn.

3. The electric cell of claim 2, wherein, The area ratio of the recessed structure (210) in the first turn of the electrode and the area ratio of the recessed structure (210) in the last turn of the electrode are the area difference, and the product of the area difference and the diameter (D) of the cell satisfies 1 to 40.

4. The cell of any of claims 1-3, wherein, The plurality of said recessed structures (210) are arranged at intervals along the length of the active material layer (2), or the plurality of said recessed structures (210) are arranged in an array on the active material layer (2).

5. The electric cell of claim 4, wherein, The recessed structure (210) is constructed as a circular groove, and the number of the circular grooves is multiple and arranged at intervals on the surface of the active material layer (2).

6. The electric cell of claim 5, wherein, The circular groove is recessed inward along the thickness direction of the active material layer (2), or the circular groove penetrates the active material layer (2) along the thickness direction of the active material layer (2).

7. The cell of any one of claims 1 to 3, wherein, The distance between the center of the recessed structure (210) closest to the edge of the electrode and the end face of the electrode ranges from 10 to 150 μm.

8. The battery cell according to claim 7, characterized in that, The projected area of ​​the recessed structure (210) toward the active material layer (2) is A. Among the plurality of recessed structures (210), A gradually increases along the direction from both ends of the battery cell to the middle.

9. A cylindrical battery, characterized by Includes the battery cell as described in any one of claims 1-8.

10. An electric device, characterized by Including the cylindrical battery as described in claim 9.

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