Battery cell and electric device

Abstract

A battery cell and an electric device. The battery cell comprises an electrode assembly; the electrode assembly comprises a first electrode sheet; the first electrode sheet comprises a first current collector and a first active material layer; in the thickness direction of the first current collector, at least one side of the first current collector is provided with the first active material layer; the surface of the at least one first active material layer facing away from the first current collector is provided with first recesses and second recesses at intervals; the first recesses and the second recesses are arranged at intervals in the length direction of the first current collector; and the volume of each first recess is greater than the volume of each second recess, so that the contact area between the first active material layer and an electrolyte can be increased with less loss of active materials, thereby improving the wettability and enabling the battery cell to have higher energy density and higher safety performance.

Description

Battery cells and electrical equipment

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 2025101796473, filed on February 18, 2025, entitled “Battery Cell and Electrical Equipment”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell and an electrical device. Background Technology

[0004] With the rapid development of new energy technologies, battery cells have been widely used in electronic devices, electric vehicles, electric two-wheelers, power tools, and other fields. As the application of battery cells becomes more widespread, higher requirements are being placed on their safety performance. Summary of the Invention

[0005] This application provides a battery cell and an electrical device to improve the safety performance of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell, the battery cell including an electrode assembly, the electrode assembly including a first electrode sheet, the first electrode sheet including a first current collector and a first active material layer, the first active material layer being disposed on at least one side of the first current collector along the thickness direction of the first current collector; wherein, at least one surface of the first active material layer opposite to the first current collector is provided with a first groove and a second groove at intervals, the first groove and the second groove being provided at intervals along the length direction of the first current collector, the volume of the first groove being greater than the volume of the second groove.

[0007] In one or more of the above optional embodiments, by providing a first groove and a second groove at intervals on the surface of at least one first active material layer facing away from the first current collector, the contact area between the first active material layer and the electrolyte can be increased. This facilitates the full wetting of the first electrode by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell. The volume of the first groove is larger than the volume of the second groove. Compared to providing only a larger first groove on the first active material layer, this solution reduces the loss of the first active material and the strength loss of the first electrode, resulting in better energy density and mechanical properties for the battery cell. Compared to providing only a smaller second groove on the first active material layer, this solution provides a larger contact area between the first active material layer and the electrolyte, facilitating the full wetting of the first electrode by the electrolyte, thereby improving the wetting performance of the battery cell. Therefore, this solution can increase the contact area between the first active material layer and the electrolyte with less loss of active material, improving wetting performance and thus enhancing the cycle performance and safety performance of the battery cell. Therefore, the battery cell provided by this solution can increase the contact area between the first active material layer and the electrolyte by losing less active material, thereby improving the wetting performance and enabling the battery cell to have higher energy density and higher safety performance.

[0008] In some embodiments of the first aspect of this application, the difference between the volume of the first groove and the volume of the second groove is greater than or equal to 0.07 mm3.

[0009] In one or more of the above optional embodiments, the difference between the volume of the first groove and the volume of the second groove is greater than or equal to 0.07 mm. 3 This results in a significant difference between the volume of the first groove and the volume of the second groove, which further increases the contact area between the first active material layer and the electrolyte by minimizing the loss of active material, thereby improving wetting performance and enabling the battery cell to have higher energy density and higher safety performance.

[0010] In some embodiments of the first aspect of this application, the size of the first groove is larger than the size of the second groove along the width direction of the first current collector.

[0011] In one or more of the above optional embodiments, by making the size of the first groove larger than the size of the second groove along the width direction of the first current collector, it is easier to achieve a volume of the first groove larger than the volume of the second groove. By making the size of the first groove larger than the size of the second groove along the width direction of the first current collector, compared to a solution where all grooves are of large length, this solution can improve the problem of weakened first electrode strength and greater loss of active material caused by the large length of all grooves. Compared to a solution where all grooves are of small length, this solution can improve the problem of insufficient wetting of the first electrode caused by the small length of all grooves, which is beneficial to improving the cycle performance of the battery cell. Furthermore, since the sizes of the first and second grooves are different along the width direction of the first current collector, if laser grooving is used during the manufacturing process, only the laser time needs to be adjusted to etch grooves of different lengths. If the sizes of the first and second grooves are different along the length direction of the first current collector, the laser frequency and intensity need to be adjusted, reducing the complexity of the manufacturing process.

[0012] In some embodiments of the first aspect of this application, when viewed along the thickness direction of the first current collector, the first groove and the first active material layer are separated by a distance at their opposite ends along the width direction of the first current collector, and the second groove and the first active material layer are separated by a distance at their opposite ends along the width direction of the first current collector.

[0013] In one or more of the above optional embodiments, when viewed along the thickness direction of the first current collector, the first groove and the first active material layer are both at two ends along the width direction of the first current collector, and the second groove and the first active material layer are both at two ends along the width direction of the first current collector. That is, neither the first groove nor the second groove extends to the two ends of the first active material layer along the width direction of the first current collector. Therefore, along the width direction of the first current collector, the edge region of the first electrode has better strength, reducing the risk of wrinkling or curling of the first electrode in the edge region of the width direction. This reduces the risk of problems such as lithium plating and short circuits in the cell caused by wrinkling of the first electrode, and improves the safety performance of the cell. Since both the first groove and the second groove are spaced apart from both ends of the first active material layer along the width direction of the first current collector, when it is necessary to connect the first electrode and the separator, the area between the first groove and the first active material layer, and between the second groove and the end face of the first active material layer in the width direction of the first current collector, can provide connection space for the separator to be connected to the first electrode. This provides a larger connection area for the connection of the first active material layer and the separator, which facilitates the connection of the first electrode and the separator and helps to improve the connection stability of the first electrode and the separator. It also reduces the risk of edge curling and wrinkling in the edge areas of the first electrode and the separator, thereby reducing the risk of lithium plating and short circuits in the cell caused by wrinkling and curling of the first electrode and the separator, and improving the safety performance of the cell.

[0014] In some embodiments of the first aspect of this application, when viewed along the thickness direction of the first current collector, at least one end of the first groove extends to the edge of the first active material layer along the width direction of the first current collector.

[0015] In one or more of the above optional embodiments, at least one end of the first groove extends to the edge of the first active material layer along the width direction of the first current collector, making the first groove larger in the width direction of the first current collector. This increases the volume of the first groove, allowing it to hold more electrolyte, which in turn facilitates the full wetting of the first electrode by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell. Furthermore, the extension of the first groove to the edge of the first active material layer facilitates the inflow of electrolyte into the first groove.

[0016] In some embodiments of the first aspect of this application, when viewed along the thickness direction of the first current collector, both ends of the first groove extend to the edge of the first active material layer along the width direction of the first current collector, and both ends of the second groove are at a distance from both ends of the first active material layer along the width direction of the first current collector.

[0017] In one or more of the above optional embodiments, both ends of the first groove extend to the edge of the first active material layer along the width direction of the first current collector, making the size of the first groove larger in the width direction of the first current collector. This increases the volume of the first groove, allowing it to hold more electrolyte, which in turn facilitates the full wetting of the first electrode by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell. The second groove is spaced from both ends of the first active material layer, meaning it does not extend to both ends of the first active material layer along the width direction of the first current collector. This results in better strength at the edge of the first electrode along the width direction of the first current collector, reducing the risk of wrinkling or curling at the edge of the first electrode in the width direction. This reduces the risk of lithium plating, short circuits, and other problems caused by wrinkling of the first electrode, thus improving the safety performance of the battery cell. Since there is a distance between the second groove and both ends of the first active material layer along the width direction of the first current collector, when it is necessary to connect the first electrode and the separator, the area between the end faces of the second groove and the first active material layer in the width direction of the first current collector can provide a connection space for the separator to be connected to the first electrode. This provides a larger connection area for the connection of the first active material layer and the separator, which facilitates the connection of the first electrode and the separator and helps to improve the connection stability of the first electrode and the separator. It also reduces the risk of edge curling and wrinkling in the edge areas of the first electrode and the separator, thereby reducing the risk of lithium plating and short circuits in the cell caused by wrinkling and curling of the first electrode and the separator, and improving the safety performance of the cell.

[0018] In some embodiments of the first aspect of this application, the first active material layer is provided with a plurality of first grooves and a plurality of second grooves, and the first grooves and second grooves are alternately arranged along the length direction of the first current collector.

[0019] In one or more of the above optional embodiments, by alternating the first groove and the second groove along the length direction of the first current collector, it is beneficial to uniformly wet the first electrode sheet, so that the battery cell has high cycle performance.

[0020] In some embodiments of the first aspect of this application, the distance between any adjacent first groove and second groove on the surface of the first active material layer away from the first current collector is W, 0.9 μm ≤ W ≤ 2.5 μm.

[0021] In one or more of the above optional embodiments, by ensuring that the spacing between adjacent first and second grooves on the surface of the first active material layer away from the first current collector is greater than or equal to 0.9 μm, the distribution of the first and second grooves is not too dense, ensuring a reasonable number of first and second grooves and reducing active material loss during the molding process. By ensuring that the spacing between adjacent first and second grooves on the surface of the first active material layer away from the first current collector is less than or equal to 2.5 μm, a sufficient number of first and second grooves can be formed on the first active material layer, resulting in a larger contact area between the first active material layer and the electrolyte. This facilitates thorough wetting of the first electrode and improves the cycle performance of the battery cell. Therefore, 0.9 μm ≤ W ≤ 2.5 μm can both reduce active material loss during the molding process of the first and second grooves and improve the cycle performance of the battery cell.

[0022] In some embodiments of the first aspect of this application, along the width direction of the first current collector, the size of the first active material layer is L, the size of the first groove is L1, the size of the second groove is L2, 0.85≤L1 / L≤1, and 0.81≤L2 / L≤0.95.

[0023] In one or more of the above optional embodiments, by using 0.85≤L1 / L and 0.81≤L2 / L, both the first groove and the second groove have relatively large dimensions in the width direction of the first current collector. This results in a larger volume for both the first and second grooves, allowing them to hold more electrolyte. This facilitates the full wetting of the first electrode sheet by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell. By using L1 / L≤1 and L2 / L≤0.95, the dimension of the second groove in the width direction of the first current collector is smaller than the dimension of the first active material layer. This reduces the loss of the first active material and the strength loss of the first electrode sheet during the molding of the first and second grooves, which is beneficial for the battery cell to have better energy density and mechanical properties. Therefore, 0.85≤L1 / L≤1 and 0.81≤L2 / L≤0.95 not only facilitates the full wetting of the first electrode sheet by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell, but also reduces the loss of active material and the strength loss of the first electrode sheet during the molding of the first and second grooves.

[0024] In some embodiments of the first aspect of this application, 75mm≤L1≤85mm, 60mm≤L2≤80mm.

[0025] In one or more of the above optional embodiments, by using 75mm≤L1 and 60mm≤L2, both the first and second grooves have relatively large dimensions in the width direction of the first current collector, resulting in larger volumes. This allows the first and second grooves to hold more electrolyte, facilitating thorough wetting of the first electrode and thus improving the cycle performance and safety of the battery cell. By using L1≤85mm and L2≤80mm, controlling the dimensions of the first and second grooves within a reasonable range in the width direction of the first current collector reduces the loss of the first active material and the strength loss of the first electrode during the molding of the first and second grooves, resulting in better energy density and mechanical properties of the battery cell. Therefore, 75mm≤L1≤85mm and 60mm≤L2≤80mm not only facilitates thorough wetting of the first electrode by the electrolyte, thus improving the cycle performance and safety of the battery cell, but also further reduces the loss of active material and the strength loss of the first electrode during the molding process of the first and second grooves.

[0026] In some embodiments of the first aspect of this application, a plurality of first grooves are provided on the surface of the first active material layer. The plurality of first grooves are arranged at intervals along the length direction of the first current collector. The distance between any two adjacent first grooves on the surface of the first active material layer is K1, where 1.8μm≤K1≤5μm.

[0027] In one or more of the above optional embodiments, by ensuring that the spacing between adjacent first grooves on the surface of the first active material layer away from the first current collector is greater than or equal to 1.8 μm, the distribution of the first grooves is not too dense, and the number of first grooves with a large volume is reasonable, thereby reducing the loss of active material during the first groove forming process. By ensuring that the spacing between adjacent first grooves on the surface of the first active material layer away from the first current collector is less than or equal to 5 μm, it is convenient to set a sufficient number of first grooves on the first active material layer, so that the contact area between the first active material layer and the electrolyte is large, which is conducive to the full wetting of the first electrode and the battery cell having better cycle performance. Therefore, 1.8 μm ≤ K1 ≤ 5 μm can both reduce the loss of active material during the first groove forming process and improve the cycle performance of the battery cell.

[0028] In some embodiments of the first aspect of this application, a plurality of second grooves are provided on the surface of the first active material layer. The plurality of second grooves are arranged at intervals along the length direction of the first current collector. The distance between any two adjacent second grooves on the surface of the first active material layer is K2, where 1.8μm≤K2≤5μm.

[0029] In one or more of the above optional embodiments, by ensuring that the spacing between adjacent second grooves on the surface of the first active material layer away from the first current collector is greater than or equal to 1.8 μm, the distribution of the second grooves is not too dense, ensuring a reasonable number of second grooves and thus reducing the loss of active material during the second groove forming process. By ensuring that the spacing between adjacent second grooves on the surface of the first active material layer away from the first current collector is less than or equal to 5 μm, a sufficient number of second grooves can be formed on the first active material layer, resulting in a larger contact area between the first active material layer and the electrolyte. This facilitates sufficient wetting of the first electrode and improves the cycle performance of the battery cell. Therefore, 1.8 μm ≤ K2 ≤ 5 μm can both reduce the loss of active material during the second groove forming process and improve the cycle performance of the battery cell.

[0030] In some embodiments of the first aspect of this application, 2μm≤K2≤2.5μm.

[0031] In one or more of the above optional embodiments, by ensuring that the spacing between adjacent second grooves on the surface of the first active material layer away from the first current collector is greater than or equal to 2 μm, the distribution of the second grooves is not too dense, resulting in a more reasonable number of second grooves and further reducing the loss of active material during the second groove forming process. By ensuring that the spacing between adjacent second grooves on the surface of the first active material layer away from the first current collector is less than or equal to 2.5 μm, a sufficient number of second grooves can be formed on the first active material layer, resulting in a larger contact area between the first active material layer and the electrolyte. This is beneficial for the first electrode to be fully wetted, which in turn benefits the cell's cycle performance. Therefore, 2 μm ≤ K2 ≤ 2.5 μm can further reduce the loss of active material during the second groove forming process and further improve the cell's cycle performance.

[0032] In some embodiments of the first aspect of this application, the depth of the first groove and the depth of the second groove are both less than the thickness of the first active material layer.

[0033] In one or more of the above optional embodiments, if the depth of the first groove and the depth of the second groove are both less than the thickness of the first active material layer, then the first current collector at the corresponding positions of the first groove and the second groove is not exposed, reducing the risk of short circuit in the battery cell and improving the safety performance of the battery cell. Since the depth of the first groove and the depth of the second groove are less than the thickness of the first active material layer, less loss of the first active material layer occurs during the forming process of the first groove and the second groove, reducing waste of active material and saving costs.

[0034] In some embodiments of the first aspect of this application, the depth of the first groove is H1, 14μm≤H1≤20μm, and the depth of the second groove is H2, 14μm≤H2≤20μm.

[0035] In one or more of the above optional embodiments, if the depth of the first groove is greater than or equal to 14 μm and the depth of the second groove is greater than or equal to 14 μm, then the depths of the first and second grooves are relatively large, resulting in larger volumes for both grooves. This allows both grooves to hold a larger amount of electrolyte, which is beneficial for the first electrode to be fully wetted, thus improving the cycle performance of the battery cell. If the depth of the first groove is less than or equal to 20 μm and the depth of the second groove is less than or equal to 20 μm, the loss of active material during the formation of the first and second grooves is reduced. If the first electrode is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating, thus improving the safety performance of the battery cell. Therefore, 14 μm ≤ H1 ≤ 20 μm and 14 μm ≤ H2 ≤ 20 μm are beneficial for both improving the cycle performance of the battery cell and reducing the loss of active material.

[0036] In some embodiments of the first aspect of this application, 15μm≤H1≤17μm, 15μm≤H2≤17μm.

[0037] In one or more of the above optional embodiments, if the depth of the first groove is greater than or equal to 15 μm and the depth of the second groove is greater than or equal to 15 μm, then the depths of the first and second grooves are larger, resulting in larger volumes of both grooves. This allows both grooves to hold more electrolyte, which is beneficial for the first electrode to be fully wetted, further improving the cycle performance of the cell. If the depth of the first groove is less than or equal to 17 μm and the depth of the second groove is less than or equal to 17 μm, the loss of active material during the formation of the first and second grooves is reduced. If the first electrode is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating and improving the safety performance of the cell. Therefore, 15 μm ≤ H1 ≤ 17 μm and 15 μm ≤ H2 ≤ 17 μm are beneficial for further improving the cycle performance of the cell and further reducing the loss of active material.

[0038] In some embodiments of the first aspect of this application, the width of the second groove on the surface of the first active material layer opposite to the first current collector is greater than the width of the first groove on the surface of the first active material layer opposite to the first current collector.

[0039] In one or more of the above optional embodiments, since the width of the second groove on the surface of the first active material layer away from the first current collector is greater than the width of the first groove on the surface of the first active material layer away from the first current collector, the volume of the second groove can be reduced to be smaller than the volume of the first groove by reducing the size of the second groove in other directions, which facilitates the processing and shaping of the first and second grooves.

[0040] In some embodiments of the first aspect of this application, the width of the first groove on the surface of the first active material layer away from the first current collector is W1, and the width of the second groove on the surface of the first active material layer away from the first current collector is W2, where 0.8 ≤ W1 / W2 ≤ 1.

[0041] In one or more of the above optional embodiments, by using 0.8 ≤ W1 / W2, the width difference between the first groove and the second groove on the surface of the first active material layer facing away from the first current collector is small. This is beneficial for uniform wetting of the first electrode and uniform current distribution, reducing the risk of lithium plating in the cell and improving the cell's safety performance. W1 / W2 ≤ 1 ensures that the width of the first groove on the surface of the first active material layer facing away from the first current collector is less than or equal to the width of the second groove on the same surface. This allows the volume of the second groove to be smaller than the volume of the first groove by reducing the dimensions of the second groove in other directions, thus facilitating the forming of both the first and second grooves. Therefore, 0.8 ≤ W1 / W2 ≤ 1 not only improves the cell's safety performance but also facilitates the processing and forming of the first and second grooves.

[0042] In some embodiments of the first aspect of this application, 60μm≤W1≤100μm, 60μm≤W2≤100μm.

[0043] In one or more of the above optional embodiments, by having a width of the first groove on the surface of the first active material layer facing away from the first current collector greater than or equal to 60 μm, and a width of the second groove on the surface of the first active material layer facing away from the first current collector greater than or equal to 60 μm, the first and second grooves have relatively large widths. This results in larger volumes for the first and second grooves, allowing them to hold more electrolyte. This facilitates thorough wetting of the first electrode, improves the cycle performance of the battery cell, and also makes the opening widths of the first and second grooves larger, facilitating electrolyte entry into the first and second grooves. By having a width of the first groove on the surface of the first active material layer facing away from the first current collector less than or equal to 100 μm, and a width of the second groove on the surface of the first active material layer facing away from the first current collector less than or equal to 100 μm, the loss of active material during the formation of the first and second grooves is reduced. If the first electrode is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating and improving the safety performance of the battery cell. Therefore, 60μm≤W1≤100μm and 60μm≤W2≤100μm are beneficial to improving the cycle performance of the battery cell and reducing the loss of active material.

[0044] In some embodiments of the first aspect of this application, 70μm≤W1≤80μm, 70μm≤W2≤80μm.

[0045] In one or more of the above optional embodiments, by having a width of the first groove on the surface of the first active material layer facing away from the first current collector greater than or equal to 70 μm, and a width of the second groove on the surface of the first active material layer facing away from the first current collector greater than or equal to 70 μm, the first and second grooves have larger widths, resulting in larger volumes of the first and second grooves. This allows both the first and second grooves to hold more electrolyte, further facilitating the full wetting of the first electrode and improving the cycle performance of the battery cell. It also makes the opening widths of the first and second grooves larger, facilitating electrolyte entry into the first and second grooves. By having a width of the first groove on the surface of the first active material layer facing away from the first current collector less than or equal to 80 μm, and a width of the second groove on the surface of the first active material layer facing away from the first current collector less than or equal to 80 μm, the loss of active material during the formation of the first and second grooves is further reduced. If the first electrode is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating and improving the safety performance of the battery cell. Therefore, 70μm≤W1≤80μm and 70μm≤W2≤80μm are beneficial for further improving the cycle performance of the battery cell and for further reducing the loss of active material.

[0046] In some embodiments of the first aspect of this application, both the first groove and the second groove extend along the width direction of the first current collector.

[0047] In one or more of the above optional embodiments, since both the first groove and the second groove extend along the width direction of the first collector, the dimensions of the first groove and the second groove along the width direction of the first collector are relatively large, which facilitates the manufacturing and forming of the first groove and the second groove.

[0048] In some embodiments of the first aspect of this application, the first electrode is a negative electrode.

[0049] In one or more of the above optional embodiments, if the first electrode is a negative electrode, then by providing a first groove and a second groove in the active material layer of the negative electrode, the contact area between the negative electrode active material layer and the electrolyte can be increased. This facilitates the full wetting of the negative electrode by the electrolyte, reduces the risk of lithium plating, and thus improves the cycle performance and safety performance of the battery cell. The volume of the first groove is larger than the volume of the second groove. Compared to providing only a larger first groove on the negative electrode active material layer, this solution can reduce the loss of negative electrode active material and the strength loss of the first electrode, reduce the risk of lithium plating, and contribute to better energy density and mechanical properties of the battery cell. Compared to providing only a smaller second groove on the negative electrode active material layer, this solution can provide a larger contact area between the negative electrode active material layer and the electrolyte, facilitating the full wetting of the negative electrode by the electrolyte, thereby improving the wetting performance of the battery cell. Therefore, this solution can increase the contact area between the negative electrode active material layer and the electrolyte with less loss of active material, improving wetting performance and thus improving the cycle performance and safety performance of the battery cell. Therefore, the battery cell provided by this solution can increase the contact area between the negative electrode active material layer and the electrolyte by losing less active material, thereby improving the wetting performance and enabling the battery cell to have higher energy density and higher safety performance.

[0050] In some embodiments of the first aspect of this application, the electrode assembly further includes a second electrode, the first electrode and the second electrode having opposite polarities, the second electrode including a second current collector and a second active material layer, the second active material layer being disposed on at least one side of the second current collector along the thickness direction of the second electrode; when viewed along the thickness direction of the first current collector, the first groove extends beyond both ends of the second active material layer along the width direction of the first current collector, and the second groove does not extend beyond both ends of the second active material layer along the width direction of the first current collector.

[0051] In one or more of the above optional embodiments, by having the first groove extend beyond both ends of the second active material layer along the width direction of the first current collector, while the second groove does not extend beyond both ends of the second active material layer, the portion of the first active material layer extending beyond the second active material layer can have better wetting properties, thereby improving the cycle performance of the battery cell. The fact that the second groove does not extend beyond both ends of the second active material layer along the width direction of the first current collector helps ensure the strength of the portion of the first electrode sheet extending beyond the second active material layer along the width direction of the first current collector, reducing the risk of the first electrode sheet curling. This reduces the risk of lithium plating, short circuits, and other problems caused by wrinkling and curling of the first electrode sheet and the separator, thus improving the safety performance of the battery cell.

[0052] In some embodiments of the first aspect of this application, along the width direction of the first current collector, the minimum distance between any end of the first groove and the end of the second active material layer is G1, and the minimum distance between any end of the second groove and the end of the second active material layer is G2, where 0.2mm≤G1≤1mm and 0.2mm≤G2≤1mm.

[0053] In one or more of the above optional embodiments, by ensuring that the minimum distance between any end of the first groove and the end of the second active material layer along the width direction of the first current collector is greater than or equal to 0.2 mm, the volume of the portion of the first groove extending beyond the second active material layer in the first active material layer is relatively large, which is beneficial for improving the wetting of the first electrode and enhancing the cycle performance of the battery cell. By ensuring that the minimum distance between any end of the first groove and the end of the second active material layer along the width direction of the first current collector is less than or equal to 1 mm, it is beneficial for reducing the loss of active material during the forming process of the first groove and enhancing the energy density of the battery cell. Therefore, 0.2 mm ≤ G1 ≤ 1 mm can both improve the wetting effect of the first electrode and enhance the cycle performance of the battery cell, while also reducing the loss of active material and enhancing the energy density of the battery cell. Since the two ends of the second groove do not extend beyond the two ends of the second active material layer along the width direction of the first current collector, and the minimum distance between any end of the second groove and the end of the second active material layer along the width direction of the first current collector is greater than or equal to 0.2 mm, it is beneficial to reduce the loss of active material during the molding process of the second groove, improve the energy density of the cell, and make the edge region of the first electrode sheet in the width direction of the first current collector better, reducing the risk of the first electrode sheet curling. The minimum distance between any end of the second groove and the end of the second active material layer is less than or equal to 1 mm, making the size of the second groove larger in the width direction of the first current collector. A larger volume of the second groove is beneficial to improving the wetting of the first electrode sheet and improving the cycle performance of the cell. Therefore, 0.2 mm ≤ G2 ≤ ​​1 mm can improve the wetting effect of the first electrode sheet, improve the cycle performance of the cell, reduce the loss of active material, and improve the energy density of the cell.

[0054] In some embodiments of the first aspect of this application, the first groove does not extend to the edge of the first active material layer along the length direction of the first current collector, and the second groove does not extend to the edge of the first active material layer along the length direction of the first current collector.

[0055] In one or more of the above optional embodiments, the first groove and the second groove do not extend to the edge of the first active material layer along the length direction of the first current collector, which facilitates the forming of the first groove and the second groove.

[0056] In some embodiments of the first aspect of this application, a first active material layer is provided on both sides of the first current collector along the thickness direction of the first current collector, and a first groove and a second groove are provided on both sides of the first active material layer.

[0057] In one or more of the above optional embodiments, by providing a first active material layer and a second active material layer on both sides of the first current collector, the contact area between the first electrode and the electrolyte is further increased, so that the first electrode can be fully wetted, thereby further improving the cycle performance of the battery cell.

[0058] Secondly, embodiments of this application provide an electrical device, which includes the battery cell provided in any embodiment of the first aspect.

[0059] In one or more of the above optional embodiments, the battery cell provided in the first aspect embodiment has better safety performance and cycle performance, which is beneficial to improving the power safety and power reliability of electrical equipment powered by the battery cell. Attached Figure Description

[0060] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope.

[0061] Figure 1 is a cross-sectional view of a battery cell provided in some embodiments of this application;

[0062] Figure 2 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0063] Figure 3 is a cross-sectional view along line A1-A1 in Figure 2;

[0064] Figure 4 is a schematic diagram of the first electrode sheet in an unfolded state according to some other embodiments of this application;

[0065] Figure 5 is a cross-sectional view along line A2-A2 in Figure 4;

[0066] Figure 6 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0067] Figure 7 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0068] Figure 8 is a schematic diagram of the first electrode sheet in an unfolded state according to some further embodiments of this application;

[0069] Figure 9 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0070] Figure 10 is a schematic diagram of the first electrode and the second electrode after they are fitted together according to some embodiments of this application (positional relationship between the first groove and the second active material layer).

[0071] Figure 11 is a schematic diagram of the first electrode and the second electrode after they are coupled together according to some embodiments of this application (positional relationship between the second groove and the second active material layer).

[0072] Figure 12 is a schematic diagram of the first electrode in an unfolded state provided in some other embodiments of this application;

[0073] Figure 13 is a cross-sectional view along line A3-A3 in Figure 12;

[0074] Figure 14 is a schematic diagram of the first electrode sheet in an unfolded state according to some other embodiments of this application;

[0075] Figure 15 is a cross-sectional view along line A4-A4 in Figure 14.

[0076] Icons: 100-cell; 10-casing; 20-electrode assembly; 21-first electrode; 211-first current collector; 212-first active material layer; 2121-first groove; 21211-first end; 21212-second end; 21213-first region; 21214-second region; 2122-second groove; 21221-third end; 21222-fourth end; 2123-first end face; 2124-second end face; 2125-first part; 2126-second part; 213-first tab; 22-second electrode; 221-second current collector; 222-second active material layer; 23-separator; X-thickness direction of the first current collector; Y-width direction of the first current collector; Z-length direction of the first current collector. Embodiments of the present invention

[0077] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0078] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0079] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0080] In the description of the embodiments of this application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0081] Currently, judging from market trends, the application of battery cells is becoming increasingly widespread. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in power tools, drones, energy storage devices, and many other fields. As the application areas of battery cells continue to expand, the market demand is also constantly increasing, and the requirements for battery cell safety are becoming increasingly stringent.

[0082] In related technologies, to improve the wetting effect of the electrode, grooves are typically created in the active material layer of the electrode. These grooves increase the contact area between the active material layer and the electrolyte, thereby improving the wetting effect. If the groove size is too large, it will lead to significant loss of active material and reduced electrode strength, resulting in decreased energy density and safety performance of the battery cell. If the groove size is too small, the electrode wetting effect will be insufficient, leading to reduced cycle performance and safety performance of the battery cell.

[0083] Based on the above considerations, in order to improve the safety performance of the battery cell, this application provides a battery cell including an electrode assembly, the electrode assembly including a first electrode sheet, the first electrode sheet including a first current collector and a first active material layer, the first active material layer being disposed on at least one side of the first current collector along the thickness direction of the first current collector; wherein, at least one surface of the first active material layer opposite to the first current collector is provided with a first groove and a second groove at intervals, the first groove and the second groove being provided at intervals along the length direction of the first current collector, and the volume of the first groove being greater than the volume of the second groove.

[0084] At least one surface of the first active material layer facing away from the first current collector is provided with a first groove and a second groove, which can increase the contact area between the first active material layer and the electrolyte, which is conducive to the first electrode being fully wetted by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell.

[0085] The volume of the first groove is larger than that of the second groove. Compared to simply providing a larger first groove on the first active material layer, this design reduces the loss of the first active material and the strength loss of the first electrode, which is beneficial for the cell to have better energy density and mechanical properties. Compared to simply providing a smaller second groove on the first active material layer, this design provides a larger contact area between the first active material layer and the electrolyte, facilitating the full wetting of the first electrode by the electrolyte, thereby improving the cell's wetting performance. Therefore, this design can increase the contact area between the first active material layer and the electrolyte with less loss of active material, improving wetting performance and thus enhancing the cell's cycle performance and safety performance. Therefore, the cell provided by this design can increase the contact area between the first active material layer and the electrolyte with less loss of active material, improving wetting performance and resulting in a cell with higher energy density and higher safety performance.

[0086] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical equipment such as electric two-wheelers, power tools, drones, and energy storage devices. The battery cells conforming to the operating conditions of this application can also be used as the power supply system for electrical equipment, which helps improve the safety performance of the battery cells.

[0087] This application provides an embodiment of an electrical device that uses a battery cell 100 as a power source. The electrical device can be, but is not limited to, electronic devices, power tools, electric vehicles, drones, and energy storage devices. Electronic devices can include mobile phones, tablets, laptops, etc.; power tools can include electric drills, chainsaws, etc.; and electric vehicles can include electric cars, electric motorcycles, electric bicycles, etc.

[0088] As shown in Figure 1, this application provides a battery cell 100, which includes a housing 10 and an electrode assembly 20, with the electrode assembly 20 housed within the housing 10.

[0089] The outer casing 10 forms a receiving space. This receiving space can be used to house the electrode assembly 20, electrolyte, etc. The outer casing 10 can be a rigid shell, such as a steel or aluminum shell, to form a steel-cased battery cell 100 or an aluminum-cased battery cell. The outer casing 10 can also be formed of a softer material, such as an aluminum-plastic film or a steel-plastic film, to form a pouch cell. Figure 1 shows the case where the battery cell 100 is a pouch cell.

[0090] The electrode assembly 20 includes a first electrode 21, a second electrode 22, and a separator 23. The first electrode 21 and the second electrode 22 have opposite polarities; that is, one of the first electrode 21 and the second electrode 22 is the positive electrode, and the other is the negative electrode. The separator 23 provides insulation between the first electrode 21 and the second electrode 22 to reduce the risk of short circuit in the cell 100. The material of the separator 23 may include PP (polypropylene) or PE (polyethylene), etc. In this embodiment, the first electrode 21 is the negative electrode.

[0091] The electrode assembly 20 can be a wound structure, in which the first electrode 21, the separator 23, the second electrode 22, and another separator 23 are stacked in a certain order and then wound to form the wound electrode assembly 20; or, the separator 23, the first electrode 21, the other separator 23, and the second electrode 22 are stacked in a certain order and then wound to form the wound electrode assembly 20. The wound electrode assembly 20 can also be a flat wound electrode assembly 20.

[0092] The electrode assembly 20 can also be a stacked structure, with the first electrode 21, the separator 23, and the second electrode 22 stacked in a certain order to form a stacked electrode assembly 20.

[0093] As shown in Figures 2 and 3, the first electrode 21 includes a first current collector 211 and a first active material layer 212. Along the thickness direction X of the first current collector, the first active material layer 212 is disposed on at least one side of the first current collector 211.

[0094] The thickness direction X of the first current collector is the thickness direction of the first electrode 21, and the thickness direction of the first electrode 21 is the stacking direction of the first current collector 211 and the first active material layer 212.

[0095] Along the thickness direction X of the first current collector, the first current collector 211 may have a first active material layer 212 disposed on one side, or the first current collector 211 may have a first active material layer 212 disposed on both sides. In an embodiment where the first electrode 21 is a positive electrode, the first current collector 211 is a positive current collector, and the first active material layer 212 is a positive active material layer. For lithium-ion cells, the material of the positive current collector can be aluminum. The positive active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The positive current collector can be a composite current collector or a non-composite current collector.

[0096] In an embodiment where the first electrode 21 is the negative electrode, the first current collector 211 is the negative current collector, and the first active material layer 212 is the negative active material layer. For lithium-ion cells, the negative current collector can be made of copper. The negative active material layer can be made of carbon or silicon, etc. The negative current collector can be a composite current collector or a non-composite current collector.

[0097] As shown in Figure 2, the first electrode 21 also includes a first tab 213, which protrudes from one end of the first current collector 211 along the width direction Y of the first current collector. The first tab 213 and the first current collector 211 can be separately configured and connected. The connection method between the first tab 213 and the first current collector 211 can be various, such as welding, using conductive adhesive, or riveting. When the first electrode 21 is in a wound state, the width direction Y of the first current collector corresponds to the extension direction of the winding axis.

[0098] The first tab 213 and the first current collector 211 can be integrally formed, with the first tab 213 connected to one end of the first current collector 211 along the width direction Y of the first current collector. The first tab 213 and the first current collector 211 can be formed by die-cutting a substrate. The first tab 213 can be a split tab or a full tab structure. In an embodiment where the first tab 213 is a split tab, the first electrode 21 can include multiple first tabs 213, which are spaced apart along the length direction Z of the first current collector. Figure 2 shows the case where the first tab 213 is a split tab.

[0099] As shown in Figures 2-5, at least one first active material layer 212 has a first groove 2121 and a second groove 2122 spaced apart on the surface opposite to the first current collector 211. The first groove 2121 and the second groove 2122 are spaced apart along the length direction Z of the first current collector, and the volume of the first groove 2121 is greater than the volume of the second groove 2122.

[0100] The length direction Z of the first current collector is the same as the length direction of the first electrode 21. When the first electrode 21 is in a wound state, the length direction Z of the first current collector corresponds to the winding direction. When the first electrode 21 is in an unfolded state, the thickness direction X, the width direction Y, and the length direction Z of the first current collector are perpendicular to each other.

[0101] In an embodiment where a first active material layer 212 is provided on both sides of the first current collector 211, a first active material layer 212 may be provided with a first groove 2121 and a second groove 2122.

[0102] As shown in Figures 3 and 5, in an embodiment where a first active material layer 212 is provided on both sides of the first current collector 211, both first active material layers 212 may also have a first groove 2121 and a second groove 2122. By providing a first active material layer 212 and a second active material layer 222 on both sides of the first current collector 211, the contact area between the first electrode 21 and the electrolyte is further increased, allowing the first electrode 21 to be fully wetted and further improving the cycle performance of the battery cell 100.

[0103] By providing a first groove 2121 and a second groove 2122 at intervals on the surface of at least one first active material layer 212 facing away from the first current collector 211, the contact area between the first active material layer 212 and the electrolyte can be increased, which is beneficial for the first electrode 21 to be fully wetted by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell 100.

[0104] The first groove 2121 is recessed from the surface of the first active material layer 212 away from the first current collector 211 toward the first current collector 211. The first groove 2121 forms a slot on the surface of the first active material layer 212 away from the first current collector 211.

[0105] The shape of the cross-section of the first groove 2121 can be various, such as rectangular, trapezoidal, arc, etc. Figure 3 shows the case where the cross-section of the first groove 2121 is rectangular, and Figure 5 shows the case where the cross-section of the first groove 2121 is trapezoidal.

[0106] The width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is not less than the width of the first groove 2121 at other locations along the thickness direction X of the first current collector. In an embodiment where the cross-sectional shape of the first groove 2121 is trapezoidal, the long base of the trapezoid is located on the surface of the first active material layer 212 facing away from the first current collector 211, that is, the width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than the width of the first groove 2121 at other locations along the thickness direction X of the first current collector, so that the first groove 2121 forms a larger opening on the first active material layer 212, facilitating the entry of electrolyte into the first groove 2121.

[0107] The second groove 2122 is recessed from the surface of the first active material layer 212 away from the first current collector 211 toward the first current collector 211. The second groove 2122 forms a slot on the surface of the first active material layer 212 away from the first current collector 211.

[0108] The shape of the cross-section of the second groove 2122 can be various, such as rectangular, trapezoidal, arc, etc. Figure 3 shows the case where the cross-section of the second groove 2122 is rectangular, and Figure 5 shows the case where the cross-section of the second groove 2122 is trapezoidal.

[0109] The width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is not less than the width of the second groove 2122 at other locations along the thickness direction X of the first current collector. In an embodiment where the cross-sectional shape of the second groove 2122 is trapezoidal, the long base of the trapezoid is located on the surface of the first active material layer 212 facing away from the first current collector 211, that is, the width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than the width of the second groove 2122 at other locations along the thickness direction X of the first current collector, so that the second groove 2122 forms a larger opening on the first active material layer 212, facilitating the entry of electrolyte into the second groove 2122.

[0110] The volume of the first groove 2121 is the size of the space defined by the first sealing surface and the bottom surface of the first groove 2121 when a first sealing surface is established around the bottom surface of the first groove 2121 in a circumferentially closed manner. For example, if the first groove 2121 does not extend to any edge of the first active material layer 212, then the first groove 2121 has a groove side surface (first sealing surface) that is circumferentially closed along its bottom surface. The groove side surface and the bottom surface of the first groove 2121 together define the first groove 2121, and the size of the space defined by the groove side surface and the bottom surface of the first groove 2121 is the volume of the first groove 2121. When the first groove 2121 extends to the edge of the first active material layer 212, the first groove 2121 has at least one unclosed groove side surface along its bottom surface. A virtual surface flush with the edge of the first active material layer 212 can be constructed at the unclosed part of the groove side surface of the first groove 2121 with reference to the edge of the first active material layer 212. This virtual surface is connected to the groove side surface of the first groove 2121 to form a first closed surface that is circumferentially closed along the bottom surface of the first groove 2121. The size of the space defined by the bottom surface of the first groove 2121 and the first closed surface is the volume of the first groove 2121.

[0111] The volume of the first groove 2121 can be obtained directly by measuring the length, width, and depth of the first groove 2121 and then using different volume calculation formulas according to the shape of the first groove. Alternatively, the volume of the first groove 2121 can be indirectly obtained by filling the first groove 2121 with a substance that will not be absorbed by the first electrode 21 and then measuring the volume of the substance filled in the first groove 2121.

[0112] The volume of the second groove 2122 is such that when a second sealing surface is established around the bottom surface of the second groove 2122, which is circumferentially closed along the bottom surface of the second groove 2122, the size of the space defined by the second sealing surface and the bottom surface of the second groove 2122 is the volume of the second groove 2122. For example, if the second groove 2122 does not extend to any edge of the first active material layer 212, then the second groove 2122 has a side surface (second sealing surface) circumferentially closed along its bottom surface. The side surface and the bottom surface of the second groove 2122 together define the second groove 2122, and the size of the space defined by the side surface and the bottom surface of the second groove 2122 is the volume of the second groove 2122. When the second groove 2122 extends to the edge of the first active material layer 212, the second groove 2122 has at least one unclosed groove side surface along its bottom surface. A virtual surface flush with the edge of the first active material layer 212 can be constructed at the unclosed part of the groove side surface of the second groove 2122 with reference to the edge of the first active material layer 212. This virtual surface is connected to the groove side surface of the second groove 2122 to form a second closed surface that is circumferentially closed along the bottom surface of the second groove 2122. The size of the space defined by the bottom surface of the second groove 2122 and the second closed surface is the volume of the second groove 2122.

[0113] The volume of the second groove 2122 can be directly obtained by measuring its length, width, and depth, and then using different volume calculation formulas based on its shape. Alternatively, the volume of the second groove 2122 can be indirectly obtained by filling it with a substance that is not absorbed by the first electrode 21, and then measuring the volume of the substance inside the groove.

[0114] The volume of the first groove 2121 is larger than that of the second groove 2122. Compared to only having a larger first groove 2121 on the first active material layer 212, this solution can reduce the loss of the first active material and the strength loss of the first electrode 21, which is beneficial for the battery cell 100 to have better energy density and mechanical properties. Compared to only having a smaller second groove 2122 on the first active material layer 212, this solution can provide a larger contact area between the first active material layer 212 and the electrolyte, which facilitates the full wetting of the first electrode 21 by the electrolyte, thereby improving the wetting performance of the battery cell 100. Therefore, this solution can increase the contact area between the first active material layer 212 and the electrolyte with less loss of active material, improve the wetting performance, and thus improve the cycle performance and safety performance of the battery cell 100. Therefore, the battery cell 100 provided by this solution can increase the contact area between the first active material layer 212 and the electrolyte and improve the wetting performance by losing less active material, so that the battery cell 100 has higher energy density and higher safety performance.

[0115] In some embodiments, the difference between the volume of the first groove 2121 and the volume of the second groove 2122 is greater than or equal to 0.07 mm. 3 .

[0116] For example, the volume of the first groove 2121 is at least 0.07 mm larger than the volume of the second groove 2122. 3 For example, the difference between the volume of the first groove 2121 and the volume of the second groove 2122 is 0.07 mm. 3 0.08mm 3 0.1mm 3 0.2mm 3 0.3mm 3 0.4mm 3 0.5mm 3 wait.

[0117] By ensuring that the difference between the volume of the first groove 2121 and the volume of the second groove 2122 is greater than or equal to 0.07 mm3, a large difference between the volumes of the first groove 2121 and the second groove 2122 is achieved. This allows for a greater increase in the contact area between the first active material layer 212 and the electrolyte with less loss of active material, thereby improving wetting performance and enabling the battery cell 100 to have higher energy density and higher safety performance.

[0118] For the same first active material layer 212, the number of first grooves 2121 can be one or more, and the number of second grooves 2122 can be one or more. Here, "multiple" means two or more.

[0119] In embodiments where there are multiple first grooves 2121, the multiple first grooves 2121 are spaced apart. In embodiments where there are multiple second grooves 2122, the multiple second grooves 2122 are spaced apart.

[0120] For example, as shown in Figures 2-5, the first active material layer 212 is provided with a plurality of first grooves 2121 and a plurality of second grooves 2122, and the first grooves 2121 and the second grooves 2122 are alternately arranged along the length direction Z of the first current collector.

[0121] Along the length direction Z of the first collector, the first groove 2121 and the second groove 2122 are alternately arranged, which means that along the length direction Z of the first collector, a second groove 2122 is arranged between two adjacent first grooves 2121, and a first groove 2121 is arranged between two adjacent second grooves 2122.

[0122] By alternating the arrangement of the first groove 2121 and the second groove 2122 along the length direction Z of the first current collector, it is beneficial to ensure uniform wetting of the first electrode 21, so that the cell 100 has high cycle performance.

[0123] In some embodiments, the distance between any two adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is W, 0.9μm≤W≤2.5μm.

[0124] W can be the minimum distance between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 away from the first current collector 211.

[0125] It should be noted that W is merely a symbol representing the minimum distance between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211, and does not mean that the minimum distance between any two adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is the same. It can be understood that the minimum distance between any two adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 satisfies 0.9μm~2.555μm.

[0126] W can be 0.9 μm, 1 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm, 2 μm, 2.1 μm, 2.3 μm, 2.5 μm, etc.

[0127] By ensuring that the spacing between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 0.9 μm, the distribution of the first grooves 2121 and second grooves 2122 is not too dense, ensuring a reasonable number of first grooves 2121 and second grooves 2122 and reducing active material loss during the molding process. By ensuring that the spacing between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 2.5 μm, a sufficient number of first grooves 2121 and second grooves 2122 can be provided on the first active material layer 212, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This facilitates the full wetting of the first electrode 21 and contributes to better cycle performance of the battery cell 100. Therefore, 0.9μm≤W≤2.5μm can reduce the loss of active material during the molding process of the first groove 2121 and the second groove 2122, and also improve the cycle performance of the cell 100.

[0128] Furthermore, 1.1μm≤W≤2μm.

[0129] Exemplarily, W can be 1.1 μm, 1.15 μm, 1.2 μm, 1.25 μm, 1.35 μm, 1.4 μm, 1.45 μm, 1.55 μm, 1.6 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.95 μm, 2 μm, etc.

[0130] By ensuring that the spacing between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 1.1 μm, the distribution of the first grooves 2121 and second grooves 2122 is not too dense, making the number of the first grooves 2121 and second grooves 2122 more reasonable, and further reducing the loss of active material during the molding process of the first grooves 2121 and second grooves 2122. By ensuring that the spacing between adjacent first grooves 2121 and second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 2 μm, it is convenient to set a sufficient number of first grooves 2121 and second grooves 2122 on the first active material layer 212, so that the contact area between the first active material layer 212 and the electrolyte is larger, which is conducive to the full wetting of the first electrode 21 and the better cycle performance of the battery cell 100. Therefore, 1.1μm≤W≤2μm can not only further reduce the loss of active material during the forming process of the first groove 2121 and the second groove 2122, but also further improve the cycle performance of the cell 100.

[0131] In an embodiment where a plurality of first grooves 2121 are provided on the surface of the first active material layer 212, the plurality of first grooves 2121 are arranged at intervals along the length direction Z of the first current collector, and the distance between any two adjacent first grooves 2121 on the surface of the first active material layer 212 is K1, where 1.8μm≤K1≤5μm.

[0132] K1 can be the minimum spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 away from the first current collector 211.

[0133] It should be noted that K1 is merely a symbol representing the minimum spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211, and does not mean that the minimum spacing between any two adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is the same. It can be understood that the minimum spacing between any two adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 satisfies 1.8μm~5μm.

[0134] For example, K1 can be 1.8μm, 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm, 5μm, etc.

[0135] By ensuring that the spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 1.8 μm, the distribution of the first grooves 2121 is not too dense, resulting in a reasonable number of large-volume first grooves 2121, thereby reducing the loss of active material during the molding process of the first grooves 2121. Conversely, by ensuring that the spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 5 μm, a sufficient number of first grooves 2121 can be formed on the first active material layer 212, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This facilitates the full wetting of the first electrode 21 and improves the cycle performance of the battery cell 100. Therefore, 1.8 μm ≤ K1 ≤ 5 μm not only reduces the loss of active material during the molding process of the first grooves 2121 but also improves the cycle performance of the battery cell 100.

[0136] Furthermore, 2μm≤K1≤2.5μm.

[0137] The minimum spacing between any two adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is 2μm~2.5μm.

[0138] For example, K1 can be 2μm, 2.1μm, 2.15μm, 2.25μm, 2.3μm, 2.35μm, 2.45μm, 2.5μm, etc.

[0139] By ensuring that the spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 2μm, the distribution of the first grooves 2121 is not too dense, resulting in a reasonable number of large-volume first grooves 2121, thereby further reducing the loss of active material during the molding process of the first grooves 2121. By ensuring that the spacing between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 2.5μm, it is easier to set a greater number of first grooves 2121 on the first active material layer 212, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This facilitates the full wetting of the first electrode 21 and improves the cycle performance of the battery cell 100. Therefore, 2μm≤K1≤2.5μm can both reduce the loss of active material during the molding process of the first grooves 2121 and improve the cycle performance of the battery cell 100.

[0140] In an embodiment where a plurality of second grooves 2122 are provided on the surface of the first active material layer 212, the plurality of second grooves 2122 are arranged at intervals along the length direction Z of the first current collector, and the distance between any two adjacent second grooves 2122 on the surface of the first active material layer 212 is K2, 1.8μm≤K2≤5μm.

[0141] K2 can be the minimum spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 away from the first current collector 211.

[0142] It should be noted that K2 is merely a symbol representing the minimum spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211, and does not mean that the minimum spacing between any two adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is the same. It can be understood that the minimum spacing between any two adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 satisfies 1.8μm~5μm.

[0143] For example, K2 can be 1.8μm, 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, 4μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm, 5μm, etc.

[0144] By ensuring that the spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 1.8 μm, the distribution of the second grooves 2122 is not too dense, ensuring a reasonable number of second grooves 2122 and thus reducing active material loss during the molding process of the second grooves 2122. Conversely, by ensuring that the spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 5 μm, a sufficient number of second grooves 2122 can be formed on the first active material layer 212, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This facilitates thorough wetting of the first electrode 21 and improves the cycle performance of the battery cell 100. Therefore, 1.8 μm ≤ K2 ≤ 5 μm not only reduces active material loss during the molding process of the first grooves 2121 but also improves the cycle performance of the battery cell 100.

[0145] Furthermore, 2μm≤K2≤2.5μm.

[0146] The minimum spacing between any two adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is 2μm~2.5μm.

[0147] For example, K2 can be 2μm, 2.1μm, 2.15μm, 2.25μm, 2.3μm, 2.35μm, 2.45μm, 2.5μm, etc.

[0148] By ensuring that the spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is greater than or equal to 2 μm, the distribution of the second grooves 2122 is not too dense, resulting in a more reasonable number of second grooves 2122, thereby further reducing the loss of active material during the molding process of the second grooves 2122. By ensuring that the spacing between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 2.5 μm, a sufficient number of second grooves 2122 can be formed on the first active material layer 212, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This facilitates the full wetting of the first electrode 21 and contributes to better cycle performance of the battery cell 100. Therefore, 2 μm ≤ K2 ≤ 2.5 μm not only further reduces the loss of active material during the molding process of the second grooves 2122 but also further improves the cycle performance of the battery cell 100.

[0149] As shown in Figures 2 and 4, in some embodiments, the first groove 2121 and the second groove 2122 both extend along the width direction Y of the first current collector.

[0150] The extension direction of the first groove 2121 is the direction in which the size of the first groove 2121 is the largest, that is, the size of the first groove 2121 is the largest in the width direction Y of the first current collector.

[0151] The extension direction of the second groove 2122 is the direction in which the size of the second groove 2122 is the largest, that is, the size of the second groove 2122 is the largest in the width direction Y of the first current collector.

[0152] Since both the first groove 2121 and the second groove 2122 extend along the width direction Y of the first current collector, the dimensions of the first groove 2121 and the second groove 2122 along the width direction Y of the first current collector are relatively large, which facilitates the manufacturing and forming of the first groove 2121 and the second groove 2122.

[0153] As shown in Figures 2 and 4, in some embodiments, the size of the first groove 2121 is larger than the size of the second groove 2122 along the width direction Y of the first current collector.

[0154] In this configuration, along the width direction Y of the first current collector, the first groove 2121 may extend beyond both ends of the second groove 2122, or one end of the first groove 2121 may be flush with one end of the second groove 2122, with the first groove 2121 extending beyond the other end of the second groove 2122, so that the size of the first groove 2121 is larger than the size of the second groove 2122 along the width direction Y of the first current collector. Figures 2 and 4 show the first groove 2121 extending beyond both ends of the second groove 2122 along the width direction Y of the first current collector.

[0155] By making the size of the first groove 2121 larger than the size of the second groove 2122 along the width direction Y of the first current collector, it is easier to achieve a larger volume for the first groove 2121 than for the second groove 2122. Compared to a solution where all grooves are of larger length, this solution improves the problem of weakened strength of the first electrode 21 and greater loss of active material caused by larger groove lengths. Conversely, compared to a solution where all grooves are of smaller length, this solution improves the problem of insufficient wetting of the first electrode 21 caused by smaller groove lengths, thus improving the cycle performance of the battery cell 100. Furthermore, since the first groove 2121 and the second groove 2122 have different sizes along the width direction Y of the first current collector, if laser grooving is used during manufacturing, only the laser time needs to be adjusted to create grooves of different lengths. If the sizes of the first groove 2121 and the second groove 2122 are different along the length direction Z of the first current collector, the laser frequency and intensity need to be adjusted, reducing the complexity of the manufacturing process.

[0156] Of course, in other embodiments, the dimensions of the first groove 2121 and the second groove 2122 can be the same along the width direction Y of the first current collector. The volume of the first groove 2121 can be greater than the volume of the second groove 2122 by changing the dimensions of the first groove 2121 in other directions. For example, when the dimensions of the first groove 2121 and the second groove 2122 can be the same along the width direction Y of the first current collector, the depth of the first groove 2121 is greater than the depth of the second groove 2122, and the width of the first groove 2121 is greater than the width of the second groove 2122.

[0157] As shown in Figures 2 and 4, in some embodiments, when viewed along the thickness direction X of the first current collector, the first groove 2121 and the first active material layer 212 are at opposite ends along the width direction Y of the first current collector, and the second groove 2122 and the first active material layer 212 are at opposite ends along the width direction Y of the first current collector.

[0158] That is, along the width direction Y of the first current collector, the first groove 2121 does not extend to the edge of the first active material layer 212, and the second groove 2122 does not extend to the edge of the first active material layer 212.

[0159] Along the width direction Y of the first current collector, the minimum distance between the two ends of the first groove 2121 and the end of the first active material layer 212 can be the same or different. Specifically, as shown in Figures 2 and 4, along the width direction Y of the first current collector, the first groove 2121 has a first end 21211 and a second end 21212, and the first active material layer 212 has a first end face 2123 and a second end face 2124, respectively. The first end 21211 is closer to the first end face 2123 than the second end face 2124, and the second end 21212 is closer to the second end face 2124 than the first end 21211. There is a distance between the first end 21211 and the first end face 2123, and there is a distance between the second end 21212 and the second end face 2124. The distance between the first end 21211 and the first end face 2123 and the distance between the second end 21212 and the second end face 2124 can be the same or different.

[0160] Along the width direction Y of the first current collector, the minimum distance between the two ends of the second groove 2122 and the end of the first active material layer 212 can be the same or different. Specifically, as shown in Figures 2 and 4, along the width direction Y of the first current collector, the second groove 2122 has a third end 21221 and a fourth end 21222, and the first active material layer 212 has a first end face 2123 and a second end face 2124, respectively. The third end 21221 is closer to the first end face 2123 than the fourth end 21222, and the fourth end 21222 is closer to the second end face 2124 than the third end 21221. There is a distance between the third end 21221 and the first end face 2123, and there is a distance between the fourth end 21222 and the second end face 2124. The distance between the third end 21221 and the first end face 2123 and the distance between the fourth end 21222 and the second end face 2124 can be the same or different.

[0161] In Figures 2 and 4, if the first groove 2121 does not extend to any edge of the first active material layer 212, then the side surface of the first groove 2121 is a first closed surface that is circumferentially closed along the bottom surface of the first groove 2121. If the second groove 2122 does not extend to any edge of the first active material layer 212, then the side surface of the second groove 2122 is a second closed surface that is circumferentially closed along the bottom surface of the second groove 2122.

[0162] Observing along the thickness direction X of the first current collector, the first groove 2121 and the first active material layer 212 are both at both ends along the width direction Y of the first current collector, and the second groove 2122 and the first active material layer 212 are both at both ends along the width direction Y of the first current collector. That is, neither the first groove 2121 nor the second groove 2122 extends to both ends of the first active material layer 212 along the width direction Y of the first current collector. Therefore, along the width direction Y of the first current collector, the edge area of ​​the first electrode 21 has better strength, reducing the risk of wrinkling or curling of the first electrode 21 in the width direction edge area, thereby reducing the risk of lithium plating, short circuit and other problems caused by wrinkling of the first electrode 21, and improving the safety performance of the battery cell 100. Since both the first groove 2121 and the second groove 2122 are at a distance from both ends of the first active material layer 212 along the width direction Y of the first current collector, when it is necessary to connect the first electrode 21 and the separator 23, the area between the first groove 2121 and the first active material layer 212, and between the second groove 2122 and the end face of the first active material layer 212 in the width direction Y of the first current collector, can provide connection space for the separator 23 to be connected to the first electrode 21. This provides a larger connection area for the connection of the first active material layer 212 and the separator 23, which facilitates the connection of the first electrode 21 and the separator 23 and helps to improve the connection stability of the first electrode 21 and the separator 23. It also reduces the risk of edge curling and wrinkling in the edge areas of the first electrode 21 and the separator 23, thereby reducing the risk of lithium plating, short circuits, and other problems caused by wrinkling and curling of the first electrode 21 and the separator 23, and improving the safety performance of the battery cell 100.

[0163] In other embodiments, when viewed along the thickness direction X of the first current collector, at least one end of the first groove 2121 extends to the edge of the first active material layer 212 along the width direction Y of the first current collector.

[0164] In this embodiment, along the width direction Y of the first current collector, only one end of the first groove 2121 extends to the edge of the first active material layer 212, while the other end of the first groove 2121 does not extend to the edge of the first active material layer 2122. In embodiments where there are multiple first grooves 2121, as shown in FIG6, the first ends 21211 of all the first grooves 2121 may extend to the first end face 2123 of the first active material layer 2122, while the second ends 21212 of all the first grooves 2121 may not extend to the second end face 2124 of the first active material layer 2122. Alternatively, as shown in FIG7, the second ends 21212 of all the first grooves 2121 may extend to the second end face 2124 of the first active material layer 2122, while the first ends 21211 of all the first grooves 2121 may not extend to the groove of the first active material layer 212. Alternatively, the first end 21211 of a portion of the first groove 2121 extends to the first end face 2123 of the first active material layer 212, and the second end 21212 of a portion of the first groove 2121 extends to the second end face 2124 of the first active material layer 212. For example, as shown in FIG8, the first end 21211 of one of two adjacent first grooves 2121 extends to the first end face 2123 of the first active material layer 212, while the second end 21212 of that first groove 2121 does not extend to the second end face 2124 of the first active material layer 212, and the second end 21212 of the other one extends to the second end face 2124 of the first active material layer 212, while the first end 21211 of that first groove 2121 does not extend to the first end face 2123 of the first active material layer 212.

[0165] Along the width direction Y of the first current collector, the first groove 2121 can extend to the two end faces of the first active material layer 212 at both ends. As shown in FIG9, the first end 21211 of the first groove 2121 extends to the first end face 2123 of the first active material layer 2122, and the second end 21212 of the first groove 2121 extends to the second end face 2124 of the first active material layer 2122.

[0166] In embodiments where there are multiple first grooves 2121, both ends of all the first grooves 2121 may extend to the two end faces of the first active material layer 212, or both ends of a portion of the first grooves 2121 may extend to the two end faces of the first active material layer 212.

[0167] Along the width direction Y of the first current collector, at least one end of the first groove 2121 extends to the edge of the first active material layer 212, making the dimension of the first groove 2121 larger in the width direction Y of the first current collector. This increases the volume of the first groove 2121, allowing it to hold more electrolyte. This, in turn, facilitates the full wetting of the first electrode 21 by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell 100. Furthermore, the extension of the first groove 2121 to the edge of the first active material layer 212 facilitates the inflow of electrolyte into the first groove 2121.

[0168] As shown in Figure 9, in some embodiments, when viewed along the thickness direction X of the first current collector, both ends of the first groove 2121 extend to the edge of the first active material layer 212 along the width direction Y of the first current collector, and both ends of the second groove 2122 are at a distance from both ends of the first active material layer 212 along the width direction Y of the first current collector.

[0169] That is, along the width direction Y of the first current collector, neither end of the second groove 2122 extends to the two ends of the first active material layer 212.

[0170] As shown in Figure 9, the two ends of the first groove 2121 extend to the two ends of the first active material layer along the width direction Y of the first current collector. The side surface of the first groove 2121 is a non-closed structure along the circumferential direction of the bottom surface of the first groove 2121. When measuring the volume of the first groove 2121, virtual surfaces are constructed at the two ends of the first groove 2121 along the width direction Y of the first current collector. These virtual surfaces are flush with and coplanar with the two edges of the first active material layer 212 in the width direction Y of the first current collector. The virtual surfaces and the side surface of the first groove 2121 together form a first closed surface that is circumferentially closed along the bottom surface of the first groove 2121.

[0171] Along the width direction Y of the first current collector, both ends of the first groove 2121 extend to the edge of the first active material layer 212, making the size of the first groove 2121 larger in the width direction Y of the first current collector. This increases the volume of the first groove 2121, allowing it to hold more electrolyte. This facilitates the full wetting of the first electrode 21 by the electrolyte, thereby improving the cycle performance and safety performance of the cell 100. The second groove 2122 is spaced from both ends of the first active material layer 212, meaning it does not extend to both ends of the first active material layer 212 along the width direction Y of the first current collector. Therefore, the edge region of the first electrode 21 has better strength along the width direction Y of the first current collector, reducing the risk of wrinkling or curling of the first electrode 21 in the width direction. This reduces the risk of lithium plating or short circuits in the cell 100 due to wrinkling of the first electrode 21, improving the safety performance of the cell 100. Since there is a distance between the second groove 2122 and both ends of the first active material layer 212 along the width direction Y of the first current collector, when it is necessary to connect the first electrode 21 and the separator 23, the area between the end face of the second groove 2122 and the first active material layer 212 in the width direction Y of the first current collector can provide a connection space for the separator 23 to be connected to the first electrode 21. This provides a larger connection area for the connection of the first active material layer 212 and the separator 23, which facilitates the connection of the first electrode 21 and the separator 23 and helps to improve the connection stability of the first electrode 21 and the separator 23. It also reduces the risk of edge curling and wrinkling in the edge areas of the first electrode 21 and the separator 23, thereby reducing the risk of lithium plating, short circuits and other problems caused by wrinkling and curling of the first electrode 21 and the separator 23, and improving the safety performance of the battery cell 100.

[0172] As shown in Figures 2-9, in some embodiments, the first groove 2121 does not extend to the edge of the first active material layer 212 along the length direction Z of the first current collector. That is, when the first electrode 21 is in the unfolded state, when viewed along the thickness direction X of the first current collector, both ends of the first groove 2121 are at a distance from both ends of the first active material layer 212 along the length direction Z of the first current collector.

[0173] The second groove 2122 does not extend to the edge of the first active material layer along the length direction of the first current collector. That is, when the first electrode 21 is in the unfolded state, when viewed along the thickness direction X of the first current collector, both ends of the second groove 2122 are at a distance from both ends of the first active material layer 212 along the length direction Z of the first current collector.

[0174] Since neither the first groove 2121 nor the second groove 2122 extends to the edge of the first active material layer 212 along the length direction Z of the first current collector, it is convenient to form the first groove 2121 and the second groove 2122.

[0175] As shown in Figures 2, 4, and 6-9, in some embodiments, along the width direction Y of the first current collector, the size of the first active material layer 212 is L, the size of the first groove 2121 is L1, the size of the second groove 2122 is L2, 0.85≤L1 / L≤1, and 0.81≤L2 / L≤0.95.

[0176] L represents the distance between the first end face 2123 and the second end face 2124 of the first active material layer 212 along the width direction Y of the first current collector. L1 represents the distance between the first end 21211 and the second end 21212 of the first groove 2121 along the width direction Y of the first current collector. L2 represents the distance between the third end 21221 and the fourth end 21222 of the second groove 2122 along the width direction Y of the first current collector. It should be noted that L1 is merely a symbol representing the size of the first groove 2121 in the width direction Y of the first current collector, and does not mean that any two first grooves 2121 have the same size in the width direction Y of the first current collector. It can be understood that, along the width direction Y of the first current collector, the relationship between the size L1 of any first groove 2121 and the width L of the first active material layer 212 satisfies 0.85~1, and the relationship between the size L1 of any second groove 2122 and the width L of the first active material layer 212 satisfies 0.81~0.95.

[0177] For example, L1 / L can be 0.85, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1, etc.

[0178] L2 / L can be 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, etc.

[0179] By using 0.85≤L1 / L and 0.81≤L2 / L, both the first groove 2121 and the second groove 2122 have relatively large dimensions in the width direction Y of the first current collector. This results in larger volumes for both grooves 2121 and 2122, allowing them to hold more electrolyte. This increases the contact area between the electrolyte and the first active material layer 212, and facilitates thorough wetting of the first electrode 21 by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell 100. By using L1 / L≤1 and L2 / L≤0.95, the dimension of the second groove 2122 in the width direction Y of the first current collector is smaller than the dimension of the first active material layer 212. This reduces the loss of the first active material and the strength loss of the first electrode 21 during the molding process of the first groove 2121 and the second groove 2122, contributing to better energy density and mechanical properties of the battery cell 100. Therefore, 0.85≤L1 / L≤1 and 0.81≤L2 / L≤0.95 not only facilitates a larger contact area between the first active material layer 212 and the electrolyte, but also ensures that the first electrode 21 is fully wetted by the electrolyte, thereby improving the cycle performance and safety performance of the battery cell 100. Furthermore, it reduces the loss of active material and the strength loss of the first electrode 21 during the forming process of the first groove 2121 and the second groove 2122.

[0180] In some embodiments, 75mm ≤ L1 ≤ 85mm.

[0181] Understandably, the dimension of any first groove 2121 in the width direction Y of the first current collector satisfies 75mm~85mm.

[0182] For example, L1 can be 75mm, 76mm, 77mm, 78mm, 79mm, 80mm, 81mm, 82mm, 83mm, 84mm, 85mm, etc.

[0183] In some embodiments, 60mm≤L2≤80mm.

[0184] Understandably, the dimension of any second groove 2122 in the width direction Y of the first current collector satisfies 60mm~80mm.

[0185] For example, L2 can be 60mm, 62mm, 64mm, 66mm, 68mm, 70mm, 72mm, 74mm, 76mm, 78mm, 80mm, etc.

[0186] By using 75mm≤L1 and 60mm≤L2, both the first groove 2121 and the second groove 2122 have larger dimensions in the width direction Y of the first current collector, resulting in larger volumes for both grooves. This allows them to hold more electrolyte, increasing the contact area between the first active material layer 212 and the electrolyte, and ensuring the first electrode 21 is fully wetted by the electrolyte, thus improving the cycle performance and safety performance of the battery cell 100. By using L1≤85mm and L2≤80mm, the dimensions of the first groove 2121 and the second groove 2122 are controlled within a reasonable range in the width direction Y of the first current collector. This reduces the loss of the first active material and the strength loss of the first electrode 21 during the molding of the first groove 2121 and the second groove 2122, resulting in better energy density and mechanical properties for the battery cell 100. Therefore, 75mm≤L1≤85mm and 60mm≤L2≤80mm are conducive to a larger contact area between the first active material layer 212 and the electrolyte, which is conducive to the first electrode 21 being fully wetted by the electrolyte. This is beneficial to improving the cycle performance and safety performance of the battery cell 100, and can further reduce the loss of active material and the strength loss of the first electrode 21 during the forming process of the first groove 2121 and the second groove 2122.

[0187] The depth of the first groove 2121 refers to the depth to which the first groove 2121 is recessed from the surface of the first active material layer 212 away from the first current collector 211 and towards the first current collector 211. The depth of the second groove 2122 refers to the depth to which the second groove 2122 is recessed from the surface of the first active material layer 212 away from the first current collector 211 and towards the first current collector 211. In some embodiments, both the first groove 2121 and the second groove 2122 are smaller than the thickness of the first active material layer 212. In this case, the first current collector 211 at the corresponding positions of the first groove 2121 and the second groove 2122 is not exposed. This not only avoids the first current collector 211 being exposed at the corresponding positions of the first groove 2121 and the second groove 2122, reducing the risk of short circuit in the battery cell 100, but also reduces the loss of active material during the molding process of the first groove 2121 and the second groove 2122, reducing the waste of active material and saving costs.

[0188] The depth of the first groove 2121 and the depth of the second groove 2122 can be the same or different.

[0189] As shown in Figures 3 and 5, in some embodiments, the depth of the first groove 2121 is H1, where 14μm≤H1≤20μm.

[0190] H1 represents the depth of the first groove 2121, which is recessed from the surface of the first active material layer 212 away from the first current collector 211 towards the first current collector 211. H1 is merely a symbol representing the depth of the first groove 2121 and does not imply that any two first grooves 2121 have the same depth. It can be understood that the depth of any first groove 2121 satisfies 14μm~20μm.

[0191] For example, H1 can be 14μm, 14.5μm, 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.5μm, 18μm, 18.5μm, 19μm, 19.5μm, 20μm, etc.

[0192] In some embodiments, the depth of the second groove 2122 is H2, where 14μm≤H2≤20μm.

[0193] H2 represents the dimension by which the second groove 2122 is recessed from the surface of the first active material layer 212 away from the first current collector 211 towards the first current collector 211. H2 is merely a symbol representing the depth of the second groove 2122 and does not imply that any two second grooves 2122 have the same depth. It can be understood that the depth of any second groove 2122 satisfies 14μm~20μm.

[0194] For example, H2 can be 14μm, 14.5μm, 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.5μm, 18μm, 18.5μm, 19μm, 19.5μm, 20μm, etc.

[0195] If the depth of the first groove 2121 is greater than or equal to 14 μm and the depth of the second groove 2122 is greater than or equal to 14 μm, then the depths of the first groove 2121 and the second groove 2122 are relatively large, resulting in larger volumes of the first groove 2121 and the second groove 2122. This provides a larger contact area between the first active material layer 212 and the electrolyte, which is beneficial for the first electrode 21 to be fully wetted and improves the cycle performance of the cell 100. If the depth of the first groove 2121 is less than or equal to 20 μm and the depth of the second groove 2122 is less than or equal to 20 μm, then the loss of active material during the formation of the first groove 2121 and the second groove 2122 is reduced. If the first electrode 21 is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode 21 is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating and improving the safety performance of the cell 100. Therefore, 14μm≤H1≤20μm and 14μm≤H2≤20μm are beneficial to improving the cycle performance of cell 100 and reducing the loss of active material.

[0196] Furthermore, 15μm≤H1≤17μm, 15μm≤H2≤17μm.

[0197] That is, the depth of any first groove 2121 is 15μm~17μm, and the depth of any second groove 2122 is 15μm~17μm.

[0198] For example, H1 can be 15μm, 15.1μm, 15.2μm, 15.3μm, 15.4μm, 15.6μm, 15.7μm, 15.8μm, 15.9μm, 16.1μm, 16.2μm, 16.3μm, 16.4μm, 16.6μm, 16.7μm, 16.8μm, 16.9μm, 17μm, etc.

[0199] H2 can be 15μm, 15.1μm, 15.2μm, 15.3μm, 15.4μm, 15.6μm, 15.7μm, 15.8μm, 15.9μm, 16.1μm, 16.2μm, 16.3μm, 16.4μm, 16.6μm, 16.7μm, 16.8μm, 16.9μm, 17μm, etc.

[0200] With the depth of the first groove 2121 greater than or equal to 15 μm and the depth of the second groove 2122 greater than or equal to 15 μm, the depths of the first groove 2121 and the second groove 2122 are larger, resulting in larger volumes of the first groove 2121 and the second groove 2122. This allows for a larger contact area between the first active material layer 212 and the electrolyte, which is beneficial for the first electrode 21 to be fully wetted, further improving the cycle performance of the cell 100. With the depth of the first groove 2121 less than or equal to 17 μm and the depth of the second groove 2122 less than or equal to 17 μm, the loss of active material during the formation of the first groove 2121 and the second groove 2122 is reduced. If the first electrode 21 is a positive electrode, less loss of positive active material is beneficial for improving energy density; if the first electrode 21 is a negative electrode, less loss of negative active material is beneficial for reducing the risk of lithium plating and improving the safety performance of the cell 100. Therefore, 15μm≤H1≤17μm and 15μm≤H2≤17μm are beneficial to further improve the cycle performance of cell 100 and further reduce the loss of active material.

[0201] In some embodiments, the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 is greater than the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211.

[0202] In this embodiment, the width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is the dimension of the first groove 2121 along the length direction Z of the first current collector on the surface of the first active material layer 212 facing away from the first current collector 211. The width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is the dimension of the second groove 2122 along the length direction Z of the first current collector on the surface of the first active material layer 212 facing away from the first current collector 211.

[0203] Since the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 is greater than the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211, the volume of the second groove 2122 can be reduced to be smaller than the volume of the first groove 2121 by reducing the size of the second groove 2122 in other directions, thereby facilitating the processing and shaping of the first groove 2121 and the second groove 2122.

[0204] Of course, in other embodiments, the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 may be the same as the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211, or the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 may be less than the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211.

[0205] As shown in Figures 2-9, in some embodiments, the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211 is W1, and the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 is W2, where 0.8≤W1 / W2≤1.

[0206] W1 / W2 can be 0.8, 0.82, 0.84, 0.85, 0.87, 0.9, 0.91, 0.92, 0.95, 0.97, 0.98, 1, etc.

[0207] By ensuring that 0.8 ≤ W1 / W2, the width difference between the first groove 2121 and the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is small. This is beneficial for uniform wetting of the first electrode 21 and uniform current distribution, reducing the risk of lithium plating in the cell 100 and improving the safety performance of the cell 100. By ensuring that W1 / W2 ≤ 1, the width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to the width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211. This allows the volume of the second groove 2122 to be smaller than the volume of the first groove 2121 by reducing the dimensions of the second groove 2122 in other directions, thus facilitating the forming of the first groove 2121 and the second groove 2122. Therefore, 0.8 ≤ W1 / W2 ≤ 1 is beneficial for both improving the safety performance of the cell 100 and facilitating the processing and forming of the first groove 2121 and the second groove 2122.

[0208] In some embodiments, 60μm≤W1≤100μm.

[0209] W1 is merely a symbol representing the width of adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211, and does not mean that any two first grooves 2121 have the same width on the surface of the first active material layer 212 facing away from the first current collector 211. That is, the width of any first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 satisfies 60μm~100μm.

[0210] For example, W1 can be 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0211] In some embodiments, 60μm≤W2≤100μm.

[0212] W2 is merely a symbol representing the width of adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211, and does not mean that any two second grooves 2122 have the same width on the surface of the first active material layer 212 facing away from the first current collector 211. That is, the width of any second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 satisfies 60μm~100μm.

[0213] For example, W2 can be 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0214] With the width of the first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211 being greater than or equal to 60 μm, and the width of the second groove 2122 on the surface of the first active material layer 212 away from the first current collector 211 being greater than or equal to 60 μm, the first groove 2121 and the second groove 2122 have a large width, resulting in a large volume of the first groove 2121 and the second groove 2122. This allows both the first groove 2121 and the second groove 2122 to hold a large amount of electrolyte, resulting in a large contact area between the first active material layer 212 and the electrolyte. This facilitates the full wetting of the first electrode 21, improves the cycle performance of the battery cell 100, and also makes the groove opening width of the first groove 2121 and the groove opening width of the second groove 2122 larger, which facilitates the entry of electrolyte into the first groove 2121 and the second groove 2122. By ensuring that the width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 100 μm, and the width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 100 μm, the loss of active material during the formation of the first groove 2121 and the second groove 2122 is reduced. If the first electrode 21 is a positive electrode, less loss of positive active material is beneficial to improving energy density; if the first electrode 21 is a negative electrode, less loss of negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the cell 100. Therefore, 60 μm ≤ W1 ≤ 100 μm and 60 μm ≤ W2 ≤ 100 μm are beneficial to both improving the cycle performance of the cell 100 and reducing the loss of active material.

[0215] Furthermore, 70μm≤W1≤80μm, 70μm≤W2≤80μm.

[0216] That is, the width of any first groove 2121 on the surface of the first active material layer 212 away from the first current collector 211 is 70μm~80μm. For example, W1 can be 70μm, 71μm, 72μm, 73μm, 74μm, 75μm, 76μm, 77μm, 78μm, 79μm, 80μm, etc.

[0217] The width of any second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is 70μm~80μm. W2 can be 70μm, 71μm, 72μm, 73μm, 74μm, 75μm, 76μm, 77μm, 78μm, 79μm, 80μm, etc.

[0218] With the first groove 2121 having a width greater than or equal to 70 μm on the surface of the first active material layer 212 away from the first current collector 211, and the second groove 2122 having a width greater than or equal to 70 μm on the surface of the first active material layer 212 away from the first current collector 211, the first groove 2121 and the second groove 2122 have larger widths, resulting in larger volumes of the first groove 2121 and the second groove 2122. This allows both the first groove 2121 and the second groove 2122 to hold more electrolyte, resulting in a larger contact area between the first active material layer 212 and the electrolyte. This further facilitates the full wetting of the first electrode 21, further improving the cycle performance of the battery cell 100. It also makes the groove opening width of the first groove 2121 and the groove opening width of the second groove 2122 larger, making it easier for the electrolyte to enter the first groove 2121 and the second groove 2122. By ensuring that the width of the first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 is less than or equal to 80 μm, and the width of the second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is also less than or equal to 80 μm, the loss of active material during the formation of the first groove 2121 and the second groove 2122 is further reduced. If the first electrode 21 is a positive electrode, less loss of positive active material is beneficial to improving energy density; if the first electrode 21 is a negative electrode, less loss of negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the cell 100. Therefore, 70 μm ≤ W1 ≤ 80 μm and 70 μm ≤ W2 ≤ 80 μm are beneficial to further improving the cycle performance of the cell 100 and further reducing the loss of active material.

[0219] In some embodiments, the first electrode 21 is a negative electrode.

[0220] The first electrode 21 is the negative electrode. By setting a first groove 2121 and a second groove 2122 on the active material layer of the negative electrode, the contact area between the active material layer and the electrolyte can be increased. This facilitates the full wetting of the negative electrode by the electrolyte, reduces the risk of lithium plating, and thus improves the cycle performance and safety performance of the cell 100. The volume of the first groove 2121 is larger than the volume of the second groove 2122. Compared to setting only the larger first groove 2121 on the negative electrode active material layer, this solution can reduce the loss of negative electrode active material and the strength loss of the first electrode 21, reduce the risk of lithium plating, and help the cell 100 have better energy density and mechanical properties. Compared to a design with only a small second groove 2122 on the negative electrode active material layer, this solution provides a larger contact area between the negative electrode active material layer and the electrolyte, facilitating thorough wetting of the negative electrode sheet by the electrolyte and thus improving the wetting performance of the cell 100. Therefore, this solution increases the contact area between the negative electrode active material layer and the electrolyte with minimal loss of active material, improving wetting performance and consequently enhancing the cycle performance and safety performance of the cell 100. Thus, the cell 100 provided by this solution can increase the contact area between the negative electrode active material layer and the electrolyte with minimal loss of active material, improving wetting performance and resulting in higher energy density and higher safety performance.

[0221] As shown in Figures 10 and 11, in some embodiments, the electrode assembly 20 further includes a second electrode 22, the first electrode 21 and the second electrode 22 having opposite polarities, the second electrode 22 including a second current collector 221 and a second active material layer 222, the second active material layer 222 being disposed on at least one side of the second current collector 221 along the thickness direction of the second electrode 22; when viewed along the thickness direction X of the first current collector, the first groove 2121 extends beyond both ends of the second active material layer 222 along the width direction Y of the first current collector, and the second groove 2122 does not extend beyond both ends of the second active material layer 222.

[0222] In an embodiment where the first electrode 21 is a negative electrode, the second electrode 22 is a positive electrode.

[0223] Along the width direction Y of the first current collector, the first active material layer 212 extends beyond both ends of the second active material layer 222. Specifically, along the width direction Y of the first current collector, the first active material layer 212 includes a first portion 2125 and a second portion 2126 extending beyond the second active material layer 222, with the first portion 2125 and the second portion 2126 located on opposite sides of the second active material layer 222. Along the width direction Y of the first current collector, the first groove 2121 includes a first region 21213 and a second region 21214, with the first region 21213 located in the first portion 2125 and the second region 21214 located in the second portion 2126, such that the first groove 2121 extends beyond both ends of the second active material layer 222. A portion of the second groove 2122 is located in the first portion 2125, and another portion of the first groove 2121 is located in the second portion 2126, such that the second groove 2122 extends beyond both ends of the second active material layer 222.

[0224] The two ends of the second groove 2122 along the width direction Y of the first current collector can be flush with the two ends of the second active material layer 222 along the width direction Y of the first current collector, or the second active material layer 222 can extend beyond the two ends of the second groove 2122 along the width direction Y of the first current collector, so that the second groove 2122 does not extend beyond the two ends of the second active material layer 222 along the width direction Y of the first current collector. Figure 11 shows the case where the second active material layer 222 extends beyond the two ends of the second groove 2122 along the width direction Y of the first current collector.

[0225] By extending the first groove 2121 beyond both ends of the second active material layer 222 along the width direction Y of the first current collector, while the second groove 2122 does not extend beyond both ends of the second active material layer 222, the portion of the first active material layer 212 extending beyond the second active material layer 222 can have better wetting properties, thereby improving the cycle performance of the cell 100. The fact that the second groove 2122 does not extend beyond both ends of the second active material layer 222 along the width direction Y of the first current collector helps ensure the strength of the portion of the first electrode 21 extending beyond the second active material layer 222 along the width direction Y of the first current collector, reducing the risk of the first electrode 21 curling. This reduces the risk of problems such as lithium plating and short circuits in the cell 100 caused by wrinkling and curling of the first electrode 21 and the separator 23, thus improving the safety performance of the cell 100.

[0226] As shown in Figures 10 and 12, in some embodiments, along the width direction Y of the first current collector, the minimum distance between any end of the first groove 2121 and the end of the second active material layer 222 is G1, and the minimum distance between any end of the second groove 2122 and the end of the second active material layer 222 is G2, where 0.2mm≤G1≤1mm and 0.2mm≤G2≤1mm.

[0227] Along the width direction Y of the first current collector, the minimum distance between any end of the first groove 2121 and the end of the second active material layer 222 can be the dimension of the region of the first groove 2121 located in the first part 2125 along the width direction Y of the first current collector or the dimension of the region of the first groove 2121 located in the second part 2126 along the width direction Y of the first current collector.

[0228] The dimension of the first groove 2121 located in the region of the first part 2125 (first region 21213) along the width direction Y of the first current collector satisfies 0.2mm~1mm. The dimension of the first groove 2121 located in the region of the second part 2126 (second region 21214) along the width direction Y of the first current collector satisfies 0.2mm~1mm.

[0229] For example, G1 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc.

[0230] Along the width direction Y of the first current collector, the minimum distance between any end of the second groove 2122 and the end of the second active material layer 222 can be the dimension along the width direction Y of the first current collector, which is the dimension of the end of the second groove 2122 near the first part 2125 and the end of the second active material layer 222 near the first part 2125.

[0231] The dimensions of the second groove 2122 near the first part 2125 and the end of the second active material layer 222 near the first part 2125 along the width direction Y of the first current collector are 0.2mm to 1mm. The dimensions of the second groove 2122 near the second part 2126 and the end of the second active material layer near the second part 2126 along the width direction Y of the first current collector are 0.2mm to 1mm.

[0232] For example, G2 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc.

[0233] By ensuring that the minimum distance between any end of the first groove 2121 and the end of the second active material layer 222 is greater than or equal to 0.2 mm along the width direction Y of the first current collector, the volume of the portion of the first groove 2121 extending beyond the second active material layer 222 is relatively large, which is beneficial for improving the wetting of the first electrode 21 and enhancing the cycle performance of the battery cell 100. Conversely, by ensuring that the minimum distance between any end of the first groove 2121 and the end of the second active material layer 222 is less than or equal to 1 mm along the width direction Y of the first current collector, the loss of active material during the molding process of the first groove 2121 is reduced, thus increasing the energy density of the battery cell 100. Therefore, 0.2 mm ≤ G1 ≤ 1 mm can both improve the wetting effect of the first electrode 21 and enhance the cycle performance of the battery cell 100, while also reducing active material loss and increasing the energy density of the battery cell 100. Since the two ends of the second groove 2122 do not extend beyond the two ends of the second active material layer 222 along the width direction Y of the first current collector, the minimum distance between any end of the second groove 2122 and the end of the second active material layer 222 along the width direction Y of the first current collector is greater than or equal to 0.2 mm. This helps to reduce the loss of active material during the molding process of the second groove 2122, improve the energy density of the cell, and make the edge strength of the first electrode 21 in the width direction Y of the first current collector better, reducing the risk of the first electrode 21 curling. The minimum distance between any end of the second groove 2122 and the end of the second active material layer 222 is less than or equal to 1 mm, making the size of the second groove 2122 larger in the width direction Y of the first current collector. The volume of the second groove 2122 is larger, which helps to improve the wetting of the first electrode 21 and improve the cycle performance of the cell 100. Therefore, 0.2mm≤G2≤1mm can improve the wetting effect of the first electrode 21, improve the cycle performance of the cell 100, reduce the loss of active material, and increase the energy density of the cell 100.

[0234] As shown in Figures 12-15, among all the first grooves 2121 and the second grooves, at least one of the two furthest apart along the length direction Z of the first current collector can extend to the edge of the first active material layer 212 along the length direction Z of the first current collector.

[0235] Among all the first grooves 2121 and second grooves, the two furthest apart along the length direction Z of the first current collector can be two first grooves 2121, two second grooves 2122, or one can be a first groove 2121 and the other a second groove 2122. Figures 12 and 13 show the case where the two furthest apart along the length direction Z of the first current collector are two first grooves 2121, and both of these furthest apart extend to the edge of the first active material layer 212 along the length direction Z of the first current collector. In Figures 12 and 13, the two first grooves 2121 extending to the edge of the first active material layer 212 in the length direction Z of the first current collector also extend to the edge of the first active material layer 212 in the width direction Y of the first current collector. When calculating the volume of the first groove 2121, virtual surfaces that are flush with the edge of the first active material layer 212 in the width direction Y of the first current collector need to be constructed at both ends of the first groove 2121 along the width direction Y of the first current collector. On one side of the first groove 2121 extending to the edge of the first active material layer 212 in the length direction Z of the first current collector, a virtual surface that is flush with the edge of the first active material layer 212 in the width direction Y of the first current collector also needs to be constructed. All virtual surfaces and the groove side of the first groove 2121 together form a first closed surface that is circumferentially closed along the bottom surface of the first groove 2121.

[0236] Figures 14 and 15 show the case where, among all the second grooves 2122, the two furthest apart along the length Z of the first current collector are two separate second grooves 2122, and both of these furthest apart extend to the edge of the first active material layer 212 along the length Z of the first current collector. In Figures 14 and 15, if the two second grooves 2122 extending to the edge of the first active material layer 212 along the length Z of the first current collector do not extend to the edge of the first active material layer 212 along the width Y of the first current collector, then when calculating the volume of the second groove 2122, it is only necessary to construct a virtual surface flush with the edge of the first active material layer 212 along the width Y of the first current collector on one side of the second groove 2122 extending to the edge of the first active material layer 212 along the length Z of the first current collector. This virtual surface and the side surface of the second groove 2122 together form a second closed surface circumferentially closed along the bottom surface of the second groove 2122.

[0237] This application also provides an electrical device, which includes the battery cell 100 provided in any of the above embodiments.

[0238] The battery cell 100 provides electrical energy for the operation of electrical equipment. The battery cell 100 provided in any of the above embodiments has good safety performance and cycle performance, which is beneficial to improving the electrical safety and reliability of electrical equipment powered by the battery cell 100.

[0239] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art.

Claims

1. A battery cell, comprising: An electrode assembly includes a first electrode, the first electrode including a first current collector and a first active material layer, and the first active material layer is disposed on at least one side of the first current collector along the thickness direction of the first current collector. In this embodiment, at least one surface of the first active material layer facing away from the first current collector is provided with a first groove and a second groove at intervals, the first groove and the second groove are provided at intervals along the length direction of the first current collector, and the volume of the first groove is greater than the volume of the second groove.

2. The battery cell according to claim 1, wherein, The difference between the volume of the first groove and the volume of the second groove is greater than or equal to 0.07 mm. 3 .

3. The battery cell according to claim 1 or 2, wherein, Along the width direction of the first current collector, the size of the first groove is larger than the size of the second groove.

4. The battery cell according to claim 3, wherein, Viewed along the thickness direction of the first current collector, the first groove and the first active material layer are at opposite ends along the width direction of the first current collector, and the second groove and the first active material layer are at opposite ends along the width direction of the first current collector.

5. The battery cell according to claim 3 or 4, wherein, Viewed along the thickness direction of the first current collector, at least one end of the first groove extends to the edge of the first active material layer along the width direction of the first current collector.

6. The battery cell according to claim 5, wherein, Viewed along the thickness direction of the first current collector, both ends of the first groove extend to the edge of the first active material layer along the width direction of the first current collector, and both ends of the second groove are at a distance from both ends of the first active material layer along the width direction of the first current collector.

7. The battery cell according to any one of claims 1-6, wherein, The first active material layer is provided with a plurality of first grooves and a plurality of second grooves, and the first grooves and second grooves are alternately arranged along the length direction of the first current collector.

8. The battery cell according to claim 7, wherein, The distance between any two adjacent first and second grooves on the surface of the first active material layer away from the first current collector is W, where 0.9 μm ≤ W ≤ 2.5 μm.

9. The battery cell according to any one of claims 1-8, wherein, Along the width direction of the first current collector, the size of the first active material layer is L, the size of the first groove is L1, the size of the second groove is L2, 0.85≤L1 / L≤1, 0.81≤L2 / L≤0.

95.

10. The battery cell according to claim 9, wherein, 75mm≤L1≤85mm, 60mm≤L2≤80mm.

11. The battery cell according to any one of claims 1-10, wherein, The surface of the first active material layer is provided with a plurality of first grooves, which are arranged at intervals along the length direction of the first current collector. The distance between any two adjacent first grooves on the surface of the first active material layer is K1, where 1.8μm≤K1≤5μm.

12. The battery cell according to any one of claims 1-11, wherein, The surface of the first active material layer is provided with a plurality of second grooves, which are arranged at intervals along the length direction of the first current collector. The distance between any two adjacent second grooves on the surface of the first active material layer is K2, where 1.8μm≤K2≤5μm.

13. The battery cell according to any one of claims 1-12, wherein, The depth of the first groove and the depth of the second groove are both less than the thickness of the first active material layer; the depth of the first groove is H1, 14μm≤H1≤20μm, and the depth of the second groove is H2, 14μm≤H2≤20μm.

14. The battery cell according to any one of claims 1-13, wherein, The width of the second groove on the surface of the first active material layer away from the first current collector is greater than the width of the first groove on the surface of the first active material layer away from the first current collector.

15. The battery cell according to any one of claims 1-14, wherein, The width of the first groove on the surface of the first active material layer away from the first current collector is W1, and the width of the second groove on the surface of the first active material layer away from the first current collector is W2, where 0.8 ≤ W1 / W2 ≤ 1.

16. The battery cell according to claim 15, wherein, 60μm≤W1≤100μm, 60μm≤W2≤100μm.

17. The battery cell according to any one of claims 1-16, wherein, The electrode assembly further includes a second electrode, the first electrode and the second electrode have opposite polarities, the second electrode includes a second current collector and a second active material layer, and the second active material layer is disposed on at least one side of the second current collector along the thickness direction of the second electrode. Viewed along the thickness direction of the first current collector, the first groove extends beyond both ends of the second active material layer along the width direction of the first current collector, while the second groove does not extend beyond both ends of the second active material layer.

18. The battery cell according to claim 17, wherein, Along the width direction of the first current collector, the minimum distance between any end of the first groove and the end of the second active material layer is G1, and the minimum distance between any end of the second groove and the end of the second active material layer in the width direction is G2, where 0.2mm≤G1≤1mm and 0.2mm≤G2≤1mm.

19. An electrical appliance comprising a battery cell according to any one of claims 1-18.

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