Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment, the battery cell comprises an electrode assembly, a click assembly comprises a first pole piece, the first pole piece comprises a first current collector and a first active material layer, and the first active material layer is arranged on at least one side of the first current collector along the thickness direction of the first current collector; wherein a first groove and a second groove are formed in the surface, deviating from the first current collector, of at least one first active material layer at intervals, the first groove and the second groove are formed in the length direction of the first current collector at intervals, and the volume of the first groove is larger than that of the second groove; according to the invention, the contact area between the first active material layer and the electrolyte can be increased through the active material with less loss, and the infiltration performance is improved, so that the cell has higher energy density and higher safety performance.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular, to an electric core and an electrical device using the same. Background Art

[0002] With the rapid development of new energy technologies, electric cores have been widely used in fields such as electronic devices, electric vehicles, electric two-wheelers, and electric tools. With the increasingly widespread application of electric cores, higher requirements have been put forward for the safety performance of electric cores. Summary of the Invention

[0003] Embodiments of the present application provide an electric core and an electrical device using the same to improve the safety performance of the electric core.

[0004] In a first aspect, an embodiment of the present application provides an electric core, which includes an electrode assembly. The electrode assembly includes a first electrode tab. The first electrode tab includes a first current collector and a first active material layer. Along the thickness direction of the first current collector, at least one side of the first current collector is provided with a first active material layer. Wherein, a first groove and a second groove are spaced apart on the surface of at least one first active material layer facing away from the first current collector. The first groove and the second groove are spaced apart along the length direction of the first current collector. The volume of the first groove is larger than the volume of the second groove.

[0005] In one or more of the above optional embodiments, by spacing the first groove and the second groove 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, which is beneficial to the first electrode tab being fully wetted by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the electric core. The volume of the first groove is larger than the volume of the second groove. Compared with only providing a first groove with a larger volume on the first active material layer, this solution can reduce the loss of the first active material and the loss of the strength of the first electrode tab, which is beneficial to the electric core having better energy density and mechanical properties. Compared with only providing a second groove with a smaller volume on the first active material layer, this solution can provide a larger contact area between the first active material layer and the electrolyte, facilitating the first electrode tab being fully wetted by the electrolyte, thereby improving the wetting performance of the electric core. Therefore, this solution can increase the contact area between the first active material layer and the electrolyte with less loss of active materials, improve the wetting performance, and thus improve the cycle performance and safety performance of the electric core. Therefore, the electric core provided by this solution can increase the contact area between the first active material layer and the electrolyte with less loss of active materials, improve the wetting performance, so that the electric core has a higher energy density and a higher safety performance.

[0006] In some embodiments of the first aspect of the present 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 mm 3 .

[0007] 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 2 , such that there is a large difference between the volume of the first groove and the volume of the second groove, which can further achieve an increase in the contact area between the first active material layer and the electrolyte with less loss of active material, improve the wetting performance, and enable the battery cell to have a high energy density and high safety performance.

[0008] In some embodiments of the first aspect of the present application, along the width direction of the first current collector, the size of the first groove is larger than the size of the second groove.

[0009] 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 convenient to achieve that the volume of the first groove is 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 with the solution where the lengths of all grooves are larger, this solution can improve the problems of weakened strength of the first electrode plate and large loss of active material caused by the large lengths of all grooves. Compared with the solution where the lengths of all grooves are smaller, this solution can improve the problem of insufficient wetting of the first electrode plate caused by the small lengths of all grooves, which is beneficial to improving the cycling performance of the battery cell. Moreover, since the sizes of the first groove and the second groove are different along the width direction of the first current collector, if the laser grooving method is used during the manufacturing process, only the laser time needs to be adjusted to groove grooves with different lengths. If the sizes of the first groove and the second groove 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.

[0010] In some embodiments of the first aspect of the present application, when observing along the thickness direction of the first current collector, there is a distance between the two opposite ends of the first groove and the first active material layer along the width direction of the first current collector, and there is a distance between the two ends of the second groove and the first active material layer along the width direction of the first current collector.

[0011] In one or more of the above optional embodiments, when observed along the thickness direction of the first current collector, the first groove has a distance from both ends of the first active material layer along the width direction of the first current collector, and the second groove has a distance from both ends of the first active material layer along the width direction of the first current collector, that is, neither the first groove nor the second groove extends to both ends of the first active material layer along the width direction of the first current collector. Then, along the width direction of the first current collector, the strength of the edge region of the first electrode tab is better, reducing the risk of wrinkling and curling at the edge region of the first electrode tab in the width direction, thereby reducing the risk of problems such as lithium plating and short circuit in the battery cell caused by wrinkling of the first electrode tab, and improving the safety performance of the battery cell. Since along the width direction of the first current collector, both the first groove and the second groove have a distance from both ends of the first active material layer, in the case where the first electrode tab and the separator need to be connected, the region between the end faces of the first groove and the first active material layer and 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 connecting the separator to the first electrode tab, can provide a relatively large connection area for connecting the first active material layer and the separator, facilitating the connection between the first electrode tab and the separator and being conducive to improving the connection stability between the first electrode tab and the separator, reducing the risk of curling and wrinkling at the edge regions of the first electrode tab and the separator, thereby reducing the risk of problems such as lithium plating and short circuit in the battery cell caused by wrinkling and curling of the first electrode tab and the separator, and improving the safety performance of the battery cell.

[0012] In some embodiments of the first aspect of the present application, when observed 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.

[0013] In one or more of the above optional embodiments, along the width direction of the first current collector, at least one end of the first groove extends to the edge of the first active material layer, such that the size of the first groove in the width direction of the first current collector is relatively large, which is conducive to increasing the volume of the first groove, enabling more electrolyte to be accommodated in the first groove, thereby facilitating the first electrode tab to be fully wetted by the electrolyte, and thus being conducive to improving the cycle performance and safety performance of the battery cell. And the extension of the first groove to the edge of the first active material layer is conducive to the inflow of the electrolyte into the first groove.

[0014] In some embodiments of the first aspect of the present application, when observed 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 there is a distance between both ends of the second groove and both ends 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, along the width direction of the first current collector, both ends of the first groove extend to the edges of the first active material layer, such that the size of the first groove in the width direction of the first current collector is larger, which is beneficial to increasing the volume of the first groove, enabling the first groove to accommodate more electrolyte, thereby facilitating the sufficient wetting of the first electrode sheet by the electrolyte, and thus being beneficial to improving the cycle performance and safety performance of the battery cell. There is a distance between both ends of the second groove and the first active material layer, that is, the second groove does not extend to both ends of the first active material layer along the width direction of the first current collector. Then, along the width direction of the first current collector, the strength of the edge region of the first electrode sheet is better, reducing the risk of wrinkling and curling of the edge region of the first electrode sheet in the width direction, thereby reducing the risk of problems such as lithium plating and short circuit in the battery cell caused by the wrinkling of the first electrode sheet, and improving the safety performance of the battery cell. Since there is a distance between both ends of the second groove and the first active material layer along the width direction of the first current collector, in the case where the first electrode sheet and the separator need to be connected, the region 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 a connection space for connecting the separator to the first electrode sheet, can provide a larger connection area for connecting the first active material layer and the separator, facilitating the connection between the first electrode sheet and the separator and being beneficial to improving the connection stability between the first electrode sheet and the separator, reducing the risk of curling and wrinkling of the edge regions of the first electrode sheet and the separator, thereby reducing the risk of problems such as lithium plating and short circuit in the battery cell caused by the curling and wrinkling of the first electrode sheet and the separator, and improving the safety performance of the battery cell.

[0016] In some embodiments of the first aspect of the present 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 the second grooves are alternately arranged along the length direction of the first current collector.

[0017] In one or more of the above optional embodiments, by alternately arranging the first grooves and the second grooves along the length direction of the first current collector, it is beneficial to the uniform wetting of the first electrode sheet, so that the battery cell has a high cycle performance.

[0018] In some embodiments of the first aspect of the present application, the distance between any adjacent first groove and second groove on the surface of the first active material layer facing away from the first current collector is W, and 0.9μm ≤ W ≤ 2.5μm.

[0019] In one or more of the above optional embodiments, the distance between adjacent first grooves and second grooves on the surface of the first active material layer facing away from the first current collector is greater than or equal to 0.9 μm, so that the distribution of the first grooves and the second grooves is not too dense, the number of the first grooves and the second grooves is reasonable, and the loss of active material during the forming process of the first grooves and the second grooves is reduced. By making the distance between adjacent first grooves and second grooves on the surface of the first active material layer facing away from the first current collector less than or equal to 2.5 μm, it is convenient to set a sufficient number of first grooves and second 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 beneficial to the first electrode sheet being fully wetted and beneficial to the cell having good cycle performance. Therefore, 0.9 μm ≤ W ≤ 2.5 μm can not only reduce the loss of active material during the forming process of the first grooves and the second grooves, but also improve the cycle performance of the cell.

[0020] In some embodiments of the first aspect of the present application, along the width direction of the first current collector, the size of the first active material layer is L, and the size of the first groove is L 1 , and the size of the second groove is L 2 , 0.85 ≤ L 1 / L ≤ 1, 0.81 ≤ L 2 / L ≤ 0.95.

[0021] In one or more of the above optional embodiments, by 0.85 ≤ L 1 / L, 0.81 ≤ L 2 / L, the first grooves and the second grooves both have relatively large sizes in the width direction of the first current collector, so that the volumes of the first grooves and the second grooves are both large, and more electrolyte can be accommodated in the first grooves and the second grooves, which is beneficial to the first electrode sheet being fully wetted by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the cell. By L 1 / L ≤ 1, L 2 / L ≤ 0.95, the size of the second groove in the width direction of the first current collector is smaller than the size of the first active material layer, which can reduce the loss of the first active material and the loss of the strength of the first electrode sheet during the forming process of the first grooves and the second grooves, and is beneficial to the cell having good energy density and mechanical properties. Therefore, 0.85 ≤ L 1 / L ≤ 1, 0.81 ≤ L 2 / L ≤ 0.95 is beneficial to the first electrode sheet being fully wetted by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the cell, and can also reduce the loss of active material and the loss of the strength of the first electrode sheet during the forming process of the first grooves and the second grooves.

[0022] In some embodiments of the first aspect of the present application, 75 mm ≤ L 1≤85 mm, 60 mm ≤ L 2 ≤80 mm.

[0023] In one or more of the above optional embodiments, by 75 mm ≤ L 1 , 60 mm ≤ L 2 , the first groove and the second groove both have relatively large dimensions in the width direction of the first current collector, so that the first groove and the second groove both have larger volumes, so that more electrolyte can be accommodated in the first groove and the second groove, which is beneficial to the first electrode being fully wetted by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the battery cell. By L 1 ≤85 mm, L 2 ≤80 mm, controlling the dimensions of the first groove and the second groove in the width direction of the first current collector within a reasonable range can reduce the loss of the first active material and the loss of the strength of the first electrode during the formation of the first groove and the second groove, which is beneficial to the battery cell having better energy density and mechanical properties. Therefore, 75 mm ≤ L 1 ≤85 mm, 60 mm ≤ L 2 ≤80 mm is both beneficial to the first electrode being fully wetted by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the battery cell, and can further reduce the loss of active material and the loss of the strength of the first electrode during the formation of the first groove and the second groove.

[0024] In some embodiments of the first aspect of the present application, a plurality of first grooves are provided on the surface of the first active material layer, and the plurality of first grooves are arranged at intervals along the length direction of the first current collector, and the distance between any two adjacent first grooves on the surface of the first active material layer is K 1 , 1.8 μm ≤ K 1 ≤5 μm.

[0025] In one or more of the above optional embodiments, by the distance between adjacent first grooves on the surface of the first active material layer facing away from the first current collector being 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 larger volumes is reasonable, thereby reducing the loss of active material during the formation of the first grooves. By the distance between adjacent first grooves on the surface of the first active material layer facing away from the first current collector being less than or equal to 5 μm, it is convenient to provide 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 relatively large, which is beneficial to the first electrode being fully wetted and beneficial to the battery cell having better cycle performance. Therefore, 1.8 μm ≤ K 1 ≤5 μm can both reduce the loss of active material during the formation of the first grooves and improve the cycle performance of the battery cell.

[0026] In some embodiments of the first aspect of the present application, a plurality of second grooves are provided on the surface of the first active material layer, and 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 K 2 , 1.8 μm ≤ K 2 ≤ 5 μm.

[0027] In one or more of the above optional embodiments, by making the distance between adjacent second grooves on the surface of the first active material layer facing away from the first current collector greater than or equal to 1.8 μm, the distribution of the second grooves is not too dense, the number of the second grooves is reasonable, and thus the loss of the active material during the formation of the second grooves is reduced. By making the distance between adjacent second grooves on the surface of the first active material layer facing away from the first current collector less than or equal to 5 μm, it is convenient to provide a sufficient number of second 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 beneficial to the first electrode being fully wetted and beneficial to the cell having good cycling performance. Therefore, 1.8 μm ≤ K 2 ≤ 5 μm can not only reduce the loss of the active material during the formation of the second grooves, but also improve the cycling performance of the cell.

[0028] In some embodiments of the first aspect of the present application, 2 μm ≤ K 2 ≤ 2.5 μm.

[0029] In one or more of the above optional embodiments, by making the distance between adjacent second grooves on the surface of the first active material layer facing away from the first current collector greater than or equal to 2 μm, the distribution of the second grooves is not too dense, the number of the second grooves is more reasonable, and thus the loss of the active material during the formation of the second grooves is further reduced. By making the distance between adjacent second grooves on the surface of the first active material layer facing away from the first current collector less than or equal to 2.5 μm, it is convenient to provide a sufficient number of second 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 beneficial to the first electrode being fully wetted and beneficial to the cell having good cycling performance. Therefore, 2 μm ≤ K 2 ≤ 2.5 μm can not only further reduce the loss of the active material during the formation of the second grooves, but also further improve the cycling performance of the cell.

[0030] In some embodiments of the first aspect of the present 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.

[0031] In one or more of the above optional embodiments, since 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 first current collector at the corresponding positions of the first groove and the second groove is not exposed, reducing the risk of short circuit of 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, during the formation process of the first groove and the second groove, less loss of the first active material layer occurs, reducing the waste of active materials and saving costs.

[0032] In some embodiments of the first aspect of the present application, the depth of the first groove is H 1 , 14 μm ≤ H 1 ≤ 20 μm, and the depth of the second groove is H 2 , 14 μm ≤ H 2 ≤ 20 μm.

[0033] In one or more of the above optional embodiments, since 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, the depths of the first groove and the second groove are relatively large, so that the volumes of the first groove and the second groove are both relatively large, enabling both the first groove and the second groove to accommodate more electrolyte, which is conducive to the first electrode being fully wetted and improving the cycle performance of the battery cell. Since 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 substances during the formation process of the first groove and the second groove is reduced. If the first electrode is a positive electrode, less loss of the positive active substance is beneficial to improving the energy density. If the first electrode is a negative electrode, less loss of the negative active substance is beneficial to reducing the risk of lithium deposition and improving the safety performance of the battery cell. Therefore, 14 μm ≤ H 1 ≤ 20 μm, 14 μm ≤ H 2 ≤ 20 μm, which is beneficial to improving the cycle performance of the battery cell and can also reduce the loss of active substances.

[0034] In some embodiments of the first aspect of the present application, 15 μm ≤ H 1 ≤ 17 μm, 15 μm ≤ H 2 ≤ 17 μm.

[0035] In one or more of the above optional embodiments, when 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, the depths of the first groove and the second groove are greater, so that the volumes of the first groove and the second groove are both larger, and more electrolyte can be accommodated in both the first groove and the second groove, which is beneficial to the full wetting of the first electrode sheet and further improves the cycle performance of the battery cell. When 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 groove and the second groove is reduced. If the first electrode sheet is a positive electrode sheet, less loss of positive active material is beneficial to improving the energy density. If the first electrode sheet is a negative electrode sheet, less loss of negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the battery cell. Therefore, 15 μm ≤ H1 ≤ 17 μm and 15 μm ≤ H2 ≤ 17 μm are beneficial to further improving the cycle performance of the battery cell and further reducing the loss of active material.

[0036] In some embodiments of the first aspect of the present application, the width of the second groove on the surface of the first active material layer facing away from the first current collector is greater than the width of the first groove on the surface of the first active material layer facing away from the first current collector.

[0037] In one or more of the above optional embodiments, when the width of the second groove on the surface of the first active material layer facing away from the first current collector is greater than the width of the first groove on the surface of the first active material layer facing away from the first current collector, the volume of the second groove can be made smaller than the volume of the first groove by reducing the size of the second groove in other directions, which is convenient for the processing and forming of the first groove and the second groove.

[0038] In some embodiments of the first aspect of the present application, the width of the first groove on the surface of the first active material layer facing away from the first current collector is W 1 and the width of the second groove on the surface of the first active material layer facing away from the first current collector is W 2 , 0.8 ≤ W 1 / W 2 ≤ 1.

[0039] In one or more of the above optional embodiments, when 0.8 ≤ W 1 / W 2 , 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, which is beneficial to the uniform wetting of the first electrode sheet and the uniform current distribution, reduces the risk of lithium plating of the battery cell, and improves the safety performance of the battery cell. W 1 / W 2≤ 1, such 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 surface of the first active material layer facing away from the first current collector. The volume of the second groove can be made smaller than that of the first groove by reducing the size of the second groove in other directions, thus facilitating the formation of the first groove and the second groove. Therefore, 0.8 ≤ W 1 / W 2 ≤ 1, which is beneficial to improving the safety performance of the battery cell and also facilitates the processing and formation of the first groove and the second groove.

[0040] In some embodiments of the first aspect of the present application, 60 μm ≤ W 1 ≤ 100 μm, 60 μm ≤ W 2 ≤ 100 μm.

[0041] In one or more of the above optional embodiments, by making the 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 the 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 groove and the second groove have a relatively large width, so that the volumes of the first groove and the second groove are relatively large, enabling both the first groove and the second groove to accommodate more electrolyte. This is conducive to the first electrode being fully wetted, improving the cycle performance of the battery cell. It also makes the notch widths of the first groove and the second groove relatively large, facilitating the entry of electrolyte into the first groove and the second groove. By making the 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 the 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 groove and the second groove is reduced. If the first electrode is a positive electrode, less loss of positive active material is beneficial to improving the energy density. If the first electrode 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 battery cell. Therefore, 60 μm ≤ W 1 ≤ 100 μm, 60 μm ≤ W 2 ≤ 100 μm, which is beneficial to improving the cycle performance of the battery cell and can also reduce the loss of active material.

[0042] In some embodiments of the first aspect of the present application, 70 μm ≤ W 1 ≤ 80 μm, 70 μm ≤ W 2 ≤ 80 μm.

[0043] In one or more of the above optional embodiments, when the width of the first groove on the surface of the first active material layer facing away from the first current collector is greater than or equal to 70 μm, and the width of the second groove on the surface of the first active material layer facing away from the first current collector is greater than or equal to 70 μm, the first groove and the second groove have a larger width, so that the volumes of the first groove and the second groove are larger, and more electrolyte can be accommodated in both the first groove and the second groove, which further facilitates the full wetting of the first electrode sheet and further improves the cycling performance of the battery cell. It also makes the notch widths of the first groove and the second groove larger, facilitating the entry of the electrolyte into the first groove and the second groove. When 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 80 μm, and the width of the second groove on the surface of the first active material layer facing away from the first current collector is less than or equal to 80 μm, the loss of the active material during the formation of the first groove and the second groove is further reduced. If the first electrode sheet is a positive electrode sheet, less loss of the positive active material is beneficial to improving the energy density. If the first electrode sheet is a negative electrode sheet, less loss of the negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the battery cell. Therefore, 70 μm ≤ W 1 ≤ 80 μm, 70 μm ≤ W 2 ≤ 80 μm, which is beneficial to further improving the cycling performance of the battery cell and further reducing the loss of the active material.

[0044] In some embodiments of the first aspect of the present application, both the first groove and the second groove extend along the width direction of the first current collector.

[0045] In one or more of the above optional embodiments, when both the first groove and the second groove extend along the width direction of the first current collector, the dimensions of the first groove and the second groove along the width direction of the first current collector are larger, which facilitates the manufacturing and forming of the first groove and the second groove.

[0046] In some embodiments of the first aspect of the present application, the first electrode sheet is a negative electrode sheet.

[0047] In one or more of the above optional embodiments, if the first electrode tab is a negative electrode tab, by providing the first groove and the second groove in the active material layer of the negative electrode tab, the contact area between the negative electrode active material layer and the electrolyte can be increased, which is beneficial to the full wetting of the negative electrode tab by the electrolyte, reduces the risk of lithium deposition, and thus is beneficial to improving the cycle performance and safety performance of the battery cell. The volume of the first groove is larger than that of the second groove. Compared with only providing the first groove with a larger volume on the negative electrode active material layer, this solution can reduce the loss of negative electrode active material and the loss of the strength of the first electrode tab, reduce the risk of lithium deposition, and is beneficial to the battery cell having better energy density and mechanical properties. Compared with only providing the second groove with a smaller volume 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, facilitate the full wetting of the negative electrode tab by the electrolyte, and thus improve 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 while losing less active material, improve the wetting performance, and thus improve 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, improve the wetting performance, and enable the battery cell to have a high energy density and high safety performance.

[0048] In some embodiments of the first aspect of the present application, the electrode assembly further includes a second electrode tab. The first electrode tab and the second electrode tab have opposite polarities. The second electrode tab includes a second current collector and a second active material layer. Along the thickness direction of the second electrode tab, the second active material layer is provided on at least one side of the second current collector; when observing 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.

[0049] In one or more of the above optional embodiments, by making the first groove extend beyond both ends of the second active material layer and the second groove not extend beyond both ends of the second active material layer along the width direction of the first current collector, the portion of the first active material layer that extends beyond the second active material layer can have better wetting performance, which is beneficial to improving the cycle performance of the battery cell. Along the width direction of the first current collector, the second groove does not extend beyond both ends of the second active material layer, which is beneficial to ensuring the strength of the portion of the first electrode tab that extends beyond the second active material layer along the width direction of the first current collector, reducing the risk of curling of the first electrode tab, and thus reducing the risk of problems such as lithium deposition and short circuit in the battery cell caused by wrinkling and curling of the first electrode tab and the separator, and improving the safety performance of the battery cell.

[0050] In some embodiments of the first aspect of the present 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 G 1, the minimum distance between any end of the second groove and the end of the second active material layer is G 2 , 0.2 mm ≤ G 1 ≤ 1 mm, 0.2 mm ≤ G 2 ≤ 1 mm.

[0051] In one or more of the above optional embodiments, by 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 greater than or equal to 0.2 mm, and the volume of the first groove in the portion where the first active material layer extends beyond the second active material layer is relatively large, which is beneficial to improving the wetting of the first electrode sheet and enhancing the cycle performance of the battery cell. By 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 less than or equal to 1 mm, which is beneficial to reducing the loss of active material during the forming process of the first groove and increasing the energy density of the battery cell. Therefore, 0.2 mm ≤ G 1 ≤ 1 mm, which can not only improve the wetting effect of the first electrode sheet and enhance the cycle performance of the battery cell, but also reduce the loss of active material and increase 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 in the width direction of the first current collector, by the width direction of the first current collector, the minimum distance between any end of the second groove and the end of the second active material layer is greater than or equal to 0.2 mm, which is beneficial to reducing the loss of active material during the forming process of the second groove and increasing the energy density of the battery cell, and making the strength of the edge region of the first electrode sheet in the width direction of the first current collector better, reducing the risk of curling of the first electrode sheet. 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 in the width direction of the first current collector relatively large, and the volume of the second groove is relatively large, which is beneficial to improving the wetting of the first electrode sheet and enhancing the cycle performance of the battery cell. Therefore, 0.2 mm ≤ G 2 ≤ 1 mm, which can not only improve the wetting effect of the first electrode sheet and enhance the cycle performance of the battery cell, but also reduce the loss of active material and increase the energy density of the battery cell.

[0052] In some embodiments of the first aspect of the present 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.

[0053] In one or more of the above optional embodiments, since neither the first groove nor the second groove extends to the edge of the first active material layer along the length direction of the first current collector, it is convenient to form the first groove and the second groove.

[0054] In some embodiments of the first aspect of the present application, along the thickness direction of the first current collector, first active material layers are provided on both sides of the first current collector, and first grooves and second grooves are provided in the first active material layers on both sides.

[0055] In one or more of the above optional embodiments, first active material layers and second active material layers are provided in the first active material layers on both sides of the first current collector, further increasing the contact area between the first electrode sheet and the electrolyte, enabling the first electrode sheet to be fully wetted, and further improving the cycle performance of the battery cell.

[0056] In a second aspect, an embodiment of the present application provides an electrical device, which includes the battery cell provided in any embodiment of the first aspect.

[0057] In one or more of the above optional embodiments, the battery cell provided in the embodiment of the first aspect has good safety performance and cycle performance, which is beneficial to improving the electrical safety and reliability of the electrical device powered by the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope.

[0059] Figure 1 It is a cross-sectional view of the battery cell provided in some embodiments of the present application;

[0060] Figure 2 It is a schematic diagram of the first electrode sheet in an unfolded state provided in some embodiments of the present application;

[0061] Figure 3 For Figure 2 It is a cross-sectional view taken along the direction of A1-A1 in

[0062] Figure 4 It is a schematic diagram of the first electrode sheet in an unfolded state provided in some other embodiments of the present application;

[0063] Figure 5 For Figure 4 It is a cross-sectional view taken along the direction of A2-A2 in

[0064] Figure 6 It is a schematic diagram of the first electrode sheet in an unfolded state provided in some other embodiments of the present application;

[0065] Figure 7 It is a schematic diagram of the first electrode sheet in an unfolded state provided in some other embodiments of the present application;

[0066] Figure 8Schematic diagram of the first pole piece in the unfolded state provided by some other embodiments of the present application;

[0067] Figure 9 Schematic diagram of the first pole piece in the unfolded state provided by some more other embodiments of the present application;

[0068] Figure 10 Schematic diagram of the cooperation between the first pole piece and the second pole piece provided by some embodiments of the present application (the positional relationship between the first groove and the second active material layer);

[0069] Figure 11 Schematic diagram of the cooperation between the first pole piece and the second pole piece provided by some embodiments of the present application (the positional relationship between the second groove and the second active material layer);

[0070] Figure 12 Schematic diagram of the first pole piece in the unfolded state provided by some other more embodiments of the present application;

[0071] Figure 13 Cross-sectional view taken along the A3 - A3 direction in 12;

[0072] Figure 14 Schematic diagram of the first pole piece in the unfolded state provided by some other embodiments of the present application;

[0073] Figure 15 Cross-sectional view taken along the A4 - A4 direction in 14.

[0074] Icon: 100 - battery cell; 10 - outer shell; 20 - electrode assembly; 21 - first pole piece; 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 pole piece; 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. Detailed implementation manners

[0075] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0076] Accordingly, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0077] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0078] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0079] Currently, from the perspective of the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as in multiple fields such as electric tools, drones, and energy storage devices. With the continuous expansion of the application fields of battery cells, the market demand for them is also continuously increasing, and the requirements for the safety of battery cells are getting higher and higher.

[0080] In related technologies, in order to improve the wetting effect of the electrode sheet, grooves are usually provided in the active material layer of the electrode sheet. By providing the grooves, the contact area between the active material layer and the electrolyte can be increased, thereby improving the wetting effect of the electrode sheet. If the size of the grooves is too large, it will cause serious loss of active material and reduction in the strength of the electrode sheet, resulting in a decrease in the energy density and safety performance of the battery cell. If the size of the grooves is too small, it will lead to insufficient wetting effect of the electrode sheet, resulting in a decrease in the cycle performance and safety performance of the battery cell.

[0081] Based on the above considerations, in order to improve the safety performance of the battery cell, an embodiment of the present application provides a battery cell, which includes an electrode assembly. The electrode assembly includes a first electrode sheet. The first electrode sheet includes a first current collector and a first active material layer. Along the thickness direction of the first current collector, at least one side of the first current collector is provided with a first active material layer; wherein, first grooves and second grooves are spaced apart on the surface of at least one first active material layer facing away from the first current collector. The first grooves and the second grooves are spaced apart along the length direction of the first current collector, and the volume of the first grooves is larger than the volume of the second grooves.

[0082] On the surface of at least one first active material layer facing away from the first current collector, a first groove and a second groove are spaced apart, which can increase the contact area between the first active material layer and the electrolyte, facilitating the full wetting of the first electrode sheet by the electrolyte, thereby being beneficial to improving the cycle performance and safety performance of the battery cell.

[0083] The volume of the first groove is larger than that of the second groove. Compared with only setting the first groove with a larger volume on the first active material layer, this solution can reduce the loss of the first active material and the loss of the strength of the first electrode sheet, being beneficial to the battery cell having better energy density and mechanical properties. Compared with only setting the second groove with a smaller volume on the first active material layer, this solution can provide a larger contact area between the first active material layer and the electrolyte, facilitating the full wetting of the first electrode sheet 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 materials, improve the wetting performance, and thus improve 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 materials, improve the wetting performance, making the battery cell have a higher energy density and a higher safety performance.

[0084] The battery cell disclosed in the embodiments of the present application can be used, but is not limited to, power-consuming devices such as electric two-wheel vehicles, electric tools, drones, and energy storage devices. It is also possible to use the battery cell of the present application working conditions as the power supply system of the power-consuming device. In this way, it is beneficial to improve the safety performance of the battery cell.

[0085] The embodiments of the present application provide a power-consuming device using the battery cell 100 as a power source. The power-consuming device can be, but is not limited to, electronic devices, electric tools, electric transportation vehicles, drones, and energy storage devices. Among them, the electronic devices can include mobile phones, tablets, laptop computers, etc., the electric tools can include electric drills, electric saws, etc., and the electric transportation vehicles can include electric vehicles, electric motorcycles, electric bicycles, etc.

[0086] As Figure 1 shown, the embodiments of the present application provide a battery cell 100, which includes a housing 10 and an electrode assembly 20, and the electrode assembly 20 is accommodated in the housing 10.

[0087] The housing 10 forms an accommodation space. The accommodation space can be used to accommodate the electrode assembly 20, the electrolyte, etc. The housing 10 can be a rigid housing. For example, the housing 10 is a steel shell or an aluminum shell to form a steel shell battery cell 100 or an aluminum shell battery cell. The housing 10 can also be formed of a relatively soft material. For example, the housing 10 is an aluminum plastic film or a steel plastic film to form a soft package battery cell. Figure 1 The case where the battery cell 100 is a soft package battery cell is shown in

[0088] The electrode assembly 20 includes a first electrode tab 21, a second electrode tab 22, and a separator 23. The first electrode tab 21 and the second electrode tab 22 have opposite polarities, that is, one of the first electrode tab 21 and the second electrode tab 22 is a positive electrode tab, and the other is a negative electrode tab. The separator 23 insulates and separates the first electrode tab 21 and the second electrode tab 22 to reduce the risk of short circuit of the battery cell 100. The material of the separator 23 may include PP (polypropylene) or PE (polyethylene), etc. In this embodiment, the first electrode tab 21 is a negative electrode tab.

[0089] The electrode assembly 20 may be a wound structure. The first electrode tab 21, the separator 23, the second electrode tab 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 tab 21, another separator 23, and the second electrode tab 22 are stacked in a certain order and then wound to form the wound electrode assembly 20. The wound electrode assembly 20 may be a flat wound electrode assembly 20.

[0090] The electrode assembly 20 may also be a stacked structure. The first electrode tab 21, the separator 23, and the second electrode tab 22 are stacked in a certain order to form the stacked electrode assembly 20.

[0091] As Figure 2 、 Figure 3 shown, the first electrode tab 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.

[0092] The thickness direction X of the first current collector is the thickness direction of the first electrode tab 21, and the thickness direction of the first electrode tab 21 is the stacking direction of the first current collector 211 and the first active material layer 212.

[0093] Along the thickness direction X of the first current collector, the first active material layer 212 may be disposed on one side of the first current collector 211, or the first active material layer 212 may be disposed on both sides of the first current collector 211. In the embodiment where the first electrode tab 21 is a positive electrode tab, the first current collector 211 is a positive current collector, and the first active material layer 212 is a positive active material layer. For a lithium-ion battery cell, the material of the positive current collector may be aluminum. The positive active material layer may be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The positive current collector may be a composite current collector or a non-composite current collector.

[0094] In an embodiment where the first electrode sheet 21 is a negative electrode sheet, the first current collector 211 is a negative current collector, and the first active material layer 212 is a negative active material layer. For a lithium-ion battery cell, the material of the negative current collector can be copper. The negative active material layer can be a carbon material, a silicon material, or the like. The negative current collector can be a composite current collector or a non-composite current collector.

[0095] As Figure 2 shown, the first electrode sheet 21 further includes a first tab 213. Along the width direction Y of the first current collector, the first tab 213 protrudes from one end of the first current collector 211. The first tab 213 and the first current collector 211 can be separately provided and connected, and there can be various connection methods between the first tab 213 and the first current collector 211. For example, the first tab 213 and the first current collector 211 are connected by welding, conductive adhesive, riveting, etc. When the first electrode sheet 21 is in a wound state, the width direction Y of the first current collector corresponds to the extending direction of the winding axis.

[0096] The first tab 213 and the first current collector 211 can be integrally formed. Along the width direction Y of the first current collector, the first tab 213 is connected to one end of the first current collector 211. The first tab 213 and the first current collector 211 can be formed by die-cutting the base material. The first tab 213 can be a split tab, and the first tab 213 can also be a full-tab structure. In an embodiment where the first tab 213 is a split tab, the first electrode sheet 21 can include a plurality of first tabs 213, and the plurality of first tabs 213 are spaced along the length direction Z of the first current collector. Figure 2 The case where the first tab 213 is a split tab is shown in

[0097] As Figures 2 - 5 shown, a first groove 2121 and a second groove 2122 are spaced on the surface of at least one first active material layer 212 facing away from the first current collector 211. The first groove 2121 and the second groove 2122 are spaced along the length direction Z of the first current collector, and the volume of the first groove 2121 is larger than the volume of the second groove 2122.

[0098] The length direction Z of the first current collector is the length direction of the first electrode sheet 21. When the first electrode sheet 21 is in a wound state, the length direction Z of the first current collector corresponds to the winding direction. When the first electrode sheet 21 is in an unfolded state, the thickness direction X of the first current collector, the width direction Y of the first current collector, and the length direction Z of the first current collector are perpendicular to each other in pairs.

[0099] In an embodiment where the first active material layers 212 are provided on both sides of the first current collector 211, one of the first active material layers 212 can be provided with the first groove 2121 and the second groove 2122.

[0100] AsFigure 3 , Figure 5 As shown in Figure 5 , in the embodiment where the first active material layers 212 are provided on both sides of the first current collector 211, the two first active material layers 212 can also be provided with the first grooves 2121 and the second grooves 2122. By providing the first active material layers 212 and the second active material layers 222 on both sides of the first current collector 211, the contact area between the first electrode tab 21 and the electrolyte is further increased, so that the first electrode tab 21 can be fully wetted, and the cycling performance of the battery cell 100 is further improved.

[0101] By providing the first grooves 2121 and the second grooves 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 to the first electrode tab 21 being fully wetted by the electrolyte, thereby being beneficial to improving the cycling performance and safety performance of the battery cell 100.

[0102] The first groove 2121 is recessed from the surface of the first active material layer 212 facing away from the first current collector 211 towards the direction close to the first current collector 211. The first groove 2121 forms a notch on the surface of the first active material layer 212 facing away from the first current collector 211.

[0103] The cross-sectional shape of the first groove 2121 can be various. For example, the cross-sectional shape of the first groove 2121 can be rectangular, trapezoidal, arc-shaped, etc. Figure 3 The case where the cross-sectional shape of the first groove 2121 is rectangular is shown in Figure 3 . Figure 5 The case where the cross-sectional shape of the first groove 2121 is trapezoidal is shown in Figure 5 .

[0104] 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 positions along the thickness direction X of the first current collector. In the embodiment where the cross-sectional shape of the first groove 2121 is trapezoidal, the long bottom side 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 positions along the thickness direction X of the first current collector, so as to form a larger opening of the first groove 2121 on the first active material layer 212 to facilitate the electrolyte to enter the first groove 2121.

[0105] The second groove 2122 is recessed from the surface of the first active material layer 212 facing away from the first current collector 211 towards the direction close to the first current collector 211. The second groove 2122 forms a notch on the surface of the first active material layer 212 facing away from the first current collector 211.

[0106] The shape of the cross-section of the second groove 2122 can be various. For example, the shape of the cross-section of the second groove 2122 can be rectangular, trapezoidal, arc-shaped, etc. Figure 3 The case where the shape of the cross-section of the second groove 2122 is rectangular is shown. Figure 5 The case where the shape of the cross-section of the second groove 2122 is trapezoidal is shown.

[0107] 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 positions along the thickness direction X of the first current collector. In the embodiment where the shape of the cross-section of the second groove 2122 is trapezoidal, the long bottom side 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 positions along the thickness direction X of the first current collector, so as to form a larger opening of the second groove 2122 on the first active material layer 212, facilitating the electrolyte to enter the second groove 2122.

[0108] The volume of the first groove 2121 is the size of the space defined by the first closed surface and the bottom surface of the first groove 2121 when a first closed surface that is circumferentially closed along the outer periphery of the bottom surface of the first groove 2121 is established on the bottom surface of the first groove 2121. For example, when the first groove 2121 does not extend to any edge of the first active material layer 212, the first groove 2121 has a groove side surface (the first closed surface) that is circumferentially closed along its bottom surface. The groove side surface and the bottom surface of the first groove 2121 jointly 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 the circumference of 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 jointly form a first closed surface that is circumferentially closed along the bottom surface of the first groove 2121, and the size of the space defined by the bottom surface and the first closed surface of the first groove 2121 is the volume of the first groove 2121.

[0109] Among them, the volume of the first groove 2121 can be directly obtained by measuring the length, width and depth of the first groove 2121 and then adopting different volume calculation formulas according to the shape of the first groove. The volume of the first groove 2121 can also be indirectly obtained by filling a substance that cannot be absorbed by the first pole piece 21 into the first groove 2121 and then measuring the volume of the substance filled in the first groove 2121.

[0110] The volume of the second groove 2122 is the size of the space defined by the second closed surface and the bottom surface of the second groove 2122 when a second closed surface that is circumferentially closed along the bottom surface of the second groove 2122 is established on the outer periphery of the bottom surface of the second groove 2122. For example, when the second groove 2122 does not extend to any edge of the first active material layer 212, the second groove 2122 has a groove side surface (the second closed surface) that is circumferentially closed along its bottom surface. The groove side surface and the bottom surface of the second groove 2122 jointly define the second groove 2122, and the size of the space defined by the groove 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 a groove side surface that is at least partially unclosed circumferentially 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 jointly 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.

[0111] Among them, the volume of the second groove 2122 can be directly obtained by measuring the length, width and depth of the second groove 2122 and then adopting different volume calculation formulas according to the shape of the second groove 2122. The volume of the second groove 2122 can also be indirectly obtained by filling a substance that cannot be absorbed by the first pole piece 21 into the second groove 2122 and then measuring the volume of the substance filled in the second groove 2122.

[0112] The volume of the first groove 2121 is greater than the volume of the second groove 2122. Compared with only the first groove 2121 with a larger volume being provided 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 pole piece 21, which is conducive to the battery cell 100 having better energy density and mechanical properties. Compared with only the second groove 2122 with a smaller volume being provided 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 is convenient for achieving full infiltration of the first pole piece 21 by the electrolyte, thereby improving the infiltration performance of the battery cell 100. Therefore, this solution can increase the contact area between the first active material layer 212 and the electrolyte under the condition of less loss of active material, improve the infiltration 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 by losing less active material, improve the infiltration performance, so that the battery cell 100 has a higher energy density and higher safety performance.

[0113] 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 .

[0114] Exemplarily, the volume of the first groove 2121 is at least 0.07 mm greater 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.

[0115] 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 , so that the volume of the first groove 2121 and the groove volume of the second groove 2122 have a large difference, which can further increase the contact area between the first active material layer 212 and the electrolyte by losing less active material, improve the wetting performance, and make the battery cell 100 have higher energy density and higher safety performance.

[0116] For the same first active material layer 212 , the number of the first grooves 2121 may be one or more, and the number of the second grooves 2122 may be one or more, wherein the “more” refers to two or more.

[0117] In embodiments where the number of the first grooves 2121 is multiple, the multiple first grooves 2121 are arranged at intervals. In embodiments where the number of the second grooves 2122 is multiple, the multiple second grooves 2122 are arranged at intervals.

[0118] Exemplarily, as Figures 2 - 5 shown, the first active material layer 212 is provided with multiple first grooves 2121 and multiple 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.

[0119] The fact that the first grooves 2121 and the second grooves 2122 are alternately arranged along the length direction Z of the first current collector means that, along the length direction Z of the first current collector, one second groove 2122 is arranged between two adjacent first grooves 2121, and one first groove 2121 is arranged between two adjacent second grooves 2122.

[0120] By alternately arranging the first grooves 2121 and the second grooves 2122 along the length direction Z of the first current collector, it is beneficial to make the first pole piece 21 evenly infiltrated, so that the battery cell 100 has high cycle performance.

[0121] In some embodiments, the distance between any adjacent first groove 2121 and second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 is W, and 0.9μm ≤ W ≤ 2.5μm.

[0122] W may be the minimum distance between any adjacent first groove 2121 and second groove 2122 on the surface of the first active material layer 212 facing away from the first current collector 211.

[0123] It should be noted that W is only a characterization symbol of the minimum distance between any adjacent first groove 2121 and second groove 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 distances between any 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 are the same. It can be understood that the minimum distances between any 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 all satisfy 0.9μm to 2.555μm.

[0124] W may be 0.9μm, 1μm, 1.1μm, 1.3μm, 1.5μm, 1.7μm, 1.9μm, 2μm, 2.1μm, 2.3μm, 2.5μm, etc.

[0125] 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, so that the distribution of the first grooves 2121 and the second grooves 2122 is not too dense, the number of the first grooves 2121 and the second grooves 2122 is reasonable, and the loss of active material during the forming process of the first grooves 2121 and the second grooves 2122 is reduced. 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, which facilitates setting 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 large, which is beneficial to the first pole piece 21 being fully wetted and beneficial to the battery cell 100 having good cycling performance. Therefore, 0.9 μm ≤ W ≤ 2.5 μm can not only reduce the loss of active material during the forming process of the first grooves 2121 and the second grooves 2122, but also improve the cycling performance of the battery cell 100.

[0126] Further, 1.1 μm ≤ W ≤ 2 μm.

[0127] 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.

[0128] 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, so that the distribution of the first grooves 2121 and the second grooves 2122 is not too dense, the number of the first grooves 2121 and the second grooves 2122 is more reasonable, and the loss of active material during the forming process of the first grooves 2121 and the second grooves 2122 is further reduced. 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, which facilitates setting 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 beneficial to the first pole piece 21 being fully wetted and beneficial to the battery cell 100 having better cycling performance. Therefore, 1.1 μm ≤ W ≤ 2 μm can not only further reduce the loss of active material during the forming process of the first grooves 2121 and the second grooves 2122, but also further improve the cycling performance of the battery cell 100.

[0129] 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 K 1 , 1.8 μm ≤ K 1 ≤ 5 μm.

[0130] K1 may be the minimum distance between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211.

[0131] It should be noted that K 1 is only a characterization symbol for the minimum distance 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 distance 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 distance 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 all satisfies 1.8 μm to 5 μm.

[0132] Exemplarily, K 1 can be 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5 μm, etc.

[0133] By making the distance between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 greater than or equal to 1.8 μm, the distribution of the first grooves 2121 is not too dense, so that the number of first grooves 2121 with a larger volume is reasonable, thereby reducing the loss of active material during the forming process of the first grooves 2121. By making the distance between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 less than or equal to 5 μm, it is convenient to set a sufficient number of first grooves 2121 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 beneficial to the first electrode sheet 21 being fully wetted and beneficial to the cell 100 having good cycling performance. Therefore, 1.8 μm ≤ K 1 ≤ 5 μm can not only reduce the loss of active material during the forming process of the first grooves 2121, but also improve the cycling performance of the cell 100.

[0134] Further, 2 μm ≤ K 1 ≤ 2.5 μm.

[0135] The minimum distance 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 all satisfies 2 μm to 2.5 μm.

[0136] Exemplarily, K 1 can be 2 μm, 2.1 μm, 2.15 μm, 2.25 μm, 2.3 μm, 2.35 μm, 2.45 μm, 2.5 μm, etc.

[0137] By making the distance between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 greater than or equal to 2 μm, the distribution of the first grooves 2121 is not too dense, and the number of the first grooves 2121 with a larger volume is reasonable, thereby further reducing the loss of active material during the forming process of the first grooves 2121. By making the distance between adjacent first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 less than or equal to 2.5 μm, it is convenient to set a larger number of first grooves 2121 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 beneficial to the first electrode sheet 21 being fully wetted and beneficial to the battery cell 100 having better cycle performance. Therefore, 2 μm ≤ K 1 ≤ 2.5 μm, which can not only reduce the loss of active material during the forming process of the first grooves 2121, but also improve the cycle performance of the battery cell 100.

[0138] 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 K 2 , 1.8 μm ≤ K 2 ≤ 5 μm.

[0139] K 2 can be the minimum distance between adjacent second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211.

[0140] It should be noted that K 2 is only a characterization symbol for the minimum distance 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 distance 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 distance 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 all satisfies 1.8 μm to 5 μm.

[0141] Exemplarily, 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.

[0142] By making 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 greater than or equal to 1.8μm, the distribution of the second grooves 2122 is not too dense, the number of the second grooves 2122 is reasonable, and thus the loss of active material during the formation of the second grooves 2122 is reduced. By making 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 less than or equal to 5μm, it is convenient to set a sufficient number of 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 large, which is beneficial to the first electrode sheet 21 being fully wetted and beneficial to the battery cell 100 having good cycle performance. Therefore, 1.8μm ≤ K 2 ≤ 5μm, which can not only reduce the loss of active material during the formation of the first grooves 2121, but also improve the cycle performance of the battery cell 100.

[0143] Furthermore, 2μm ≤ K 2 ≤ 2.5μm.

[0144] 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 all satisfies 2μm to 2.5μm.

[0145] Exemplarily, K 2 can be 2μm, 2.1μm, 2.15μm, 2.25μm, 2.3μm, 2.35μm, 2.45μm, 2.5μm, etc.

[0146] By making 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 greater than or equal to 2μm, the distribution of the second grooves 2122 is not too dense, the number of the second grooves 2122 is more reasonable, and thus the loss of active material during the formation of the second grooves 2122 is further reduced. By making 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 less than or equal to 2.5μm, it is convenient to set a sufficient number of 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 large, which is beneficial to the first electrode sheet 21 being fully wetted and beneficial to the battery cell 100 having good cycle performance. Therefore, 2μm ≤ K 2≤2.5 μm, which can further reduce the loss of active material during the formation of the second groove 2122 and further improve the cycle performance of the battery cell 100.

[0147] As Figure 2 , Figure 4 shown, in some embodiments, both the first groove 2121 and the second groove 2122 extend along the width direction Y of the first current collector.

[0148] The extending 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 in the width direction Y of the first current collector is the largest.

[0149] The extending 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 in the width direction Y of the first current collector is the largest.

[0150] By both the first groove 2121 and the second groove 2122 extending along the width direction Y of the first current collector, the sizes of the first groove 2121 and the second groove 2122 in the width direction Y of the first current collector are larger, which facilitates the manufacturing and formation of the first groove 2121 and the second groove 2122.

[0151] As Figure 2 , Figure 4 shown, in some embodiments, along the width direction Y of the first current collector, the size of the first groove 2121 is larger than the size of the second groove 2122.

[0152] Among them, 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 is flush with one end of the second groove 2122, and the first groove 2121 extends beyond the other end of the second groove 2122, so that along the width direction Y of the first current collector, the size of the first groove 2121 is larger than the size of the second groove 2122. Figure 2 And Figure 4 shows that along the width direction Y of the first current collector, the first groove 2121 extends beyond both ends of the second groove 2122.

[0153] Along the width direction Y of the first current collector, the size of the first groove 2121 is larger than that of the second groove 2122, facilitating the realization that the volume of the first groove 2121 is larger than that of the second groove 2122. Along the width direction Y of the first current collector, the size of the first groove 2121 is larger than that of the second groove 2122. Compared with the solution where the lengths of all grooves are relatively large, this solution can improve the problems of weakening the strength of the first pole piece 21 and large loss of active material caused by the relatively large lengths of all grooves. Compared with the solution where the lengths of all grooves are relatively small, this solution can improve the problem of insufficient infiltration of the first pole piece 21 due to the relatively small lengths of all grooves, which is beneficial to improving the cycling performance of the battery cell 100. Moreover, the sizes of the first groove 2121 and the second groove 2122 are different along the width direction Y of the first current collector. During the manufacturing process, if the laser grooving method is used, only the laser time needs to be adjusted to groove grooves with 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.

[0154] Of course, in some other embodiments, along the width direction Y of the first current collector, the sizes of the first groove 2121 and the second groove 2122 can be the same, and the volume of the first groove 2121 can be made larger than that of the second groove 2122 by changing the sizes of the first groove 2121 in other directions. For example, when the sizes of the first groove 2121 and the second groove 2122 are the same along the width direction Y of the first current collector, the depth of the first groove 2121 is greater than that of the second groove 2122, and the width of the first groove 2121 is greater than that of the second groove 2122.

[0155] As Figure 2 、 Figure 4 shown, in some embodiments, when observed along the thickness direction X of the first current collector, there is a distance between the two opposite ends of the first groove 2121 and the first active material layer 212 along the width direction Y of the first current collector, and there is a distance between the two ends of the second groove 2122 and the first active material layer 212 along the width direction Y of the first current collector.

[0156] 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.

[0157] Along the width direction Y of the first current collector, the minimum distances between the two ends of the first groove 2121 and the ends of the first active material layer 212 can be the same or different. Specifically, as Figure 2 、 Figure 4As shown, along the width direction Y of the first current collector, the first groove 2121 has opposite first end 21211 and second end 21212, the first active material layer 212 has opposite first end face 2123 and second end face 2124, the first end 21211 is closer to the first end face 2123 than the second end face 2124, 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, there is a distance between the second end 21212 and the second end face 2124, and the distance between the first end 21211 and the first end face 2123 may be the same as or different from the distance between the second end 21212 and the second end face 2124.

[0158] Along the width direction Y of the first current collector, the minimum distances between the two ends of the second groove 2122 and the ends of the first active material layer 212 may be the same or different. Specifically, as Figure 2 、 Figure 4 shown, along the width direction Y of the first current collector, the second groove 2122 has opposite third end 21221 and fourth end 21222, the first active material layer 212 has opposite first end face 2123 and second end face 2124, the third end 21221 is closer to the first end face 2123 than the fourth end face 21222, 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, there is a distance between the fourth end 21222 and the second end face 2124, and the distance between the third end 21221 and the first end face 2123 may be the same as or different from the distance between the fourth end 21222 and the second end face 2124.

[0159] In Figure 2 、 Figure 4 where the first groove 2121 does not extend to any edge of the first active material layer 212, the groove side surface of the first groove 2121 is a first closed surface that is circumferentially closed along the groove bottom surface of the first groove 2121. Where the second groove 2122 does not extend to any edge of the first active material layer 212, the groove side surface of the second groove 2122 is a second closed surface that is circumferentially closed along the groove bottom surface of the second groove 2122.

[0160] When observing along the thickness direction X of the first current collector, there is a distance between both ends of the first groove 2121 and the first active material layer 212 along the width direction Y of the first current collector, and there is a distance between both ends of the second groove 2122 and the first active material layer 212 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. Then, along the width direction Y of the first current collector, the strength of the edge region of the first electrode tab 21 is better, reducing the risk of wrinkling and curling at the edge region of the first electrode tab 21 in the width direction, thereby reducing the risk of problems such as lithium deposition and short circuit in the battery cell 100 caused by the wrinkling of the first electrode tab 21, and improving the safety performance of the battery cell 100. Since there is a distance between both ends of the first groove 2121 and the second groove 2122 and the first active material layer 212 along the width direction Y of the first current collector, in the case where the first electrode tab 21 and the separator 23 need to be connected, the region between the end faces of the first groove 2121 and the first active material layer 212 and between 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 connecting the separator 23 to the first electrode tab 21, can provide a relatively large connection area for connecting the first active material layer 212 and the separator 23, facilitating the connection between the first electrode tab 21 and the separator 23 and being conducive to improving the connection stability between the first electrode tab 21 and the separator 23, reducing the risk of curling and wrinkling at the edge regions of the first electrode tab 21 and the separator 23, thereby reducing the risk of problems such as lithium deposition and short circuit in the battery cell 100 caused by the wrinkling and curling of the first electrode tab 21 and the separator 23, and improving the safety performance of the battery cell 100.

[0161] In some other embodiments, when observing 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.

[0162] Among them, 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, and the other end of the first groove 2121 does not extend to the edge of the first active material layer 212. Among them, in embodiments where there are multiple first grooves 2121, as Figure 6 shown, the first ends 21211 of all the first grooves 2121 can extend to the first end face 2123 of the first active material layer 212, and the second ends 21212 of all the first grooves 2121 do not extend to the second end face 2124 of the first active material layer 212. Or, as Figure 7As shown, the second ends 21212 of all the first grooves 2121 extend to the second end face 2124 of the first active material layer 212, and the first ends 21211 of all the first grooves 2121 do not extend to the grooves of the first active material layer 212. Alternatively, the first ends 21211 of some of the first grooves 2121 extend to the first end face 2123 of the first active material layer 212, and the second ends 21212 of some of the first grooves 2121 extend to the second end face 2124 of the first active material layer 212. For example, as Figure 8 shown, 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, the second end 21212 of this first groove 2121 does not extend to the second end face 2124 of the first active material layer 212, the second end 21212 of the other first groove 2121 extends to the second end face 2124 of the first active material layer 212, and the first end 21211 of this first groove 2121 does not extend to the first end face 2123 of the first active material layer 212.

[0163] Along the width direction Y of the first current collector, both ends of the first groove 2121 can extend to the two end faces of the first active material layer 212 respectively. As Figure 9 shown, the first end 21211 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 the first groove 2121 extends to the second end face 2124 of the first active material layer 212.

[0164] In embodiments where there are multiple first grooves 2121, both ends of all the first grooves 2121 can extend to the two end faces of the first active material layer 212 respectively, or both ends of some of the first grooves 2121 can extend to the two end faces of the first active material layer 212 respectively.

[0165] 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, so that the size of the first groove 2121 in the width direction Y of the first current collector is larger, which is beneficial to increasing the volume of the first groove 2121, enabling more electrolyte to be accommodated in the first groove 2121, which is beneficial to the first electrode sheet 21 being fully infiltrated by the electrolyte, and thus beneficial to improving the cycle performance and safety performance of the battery cell 100. And the extension of the first groove 2121 to the edge of the first active material layer 212 is beneficial to the inflow of the electrolyte into the first groove 2121.

[0166] As Figure 9As shown, in some embodiments, when observed along the thickness direction X of the first current collector, both ends of the first groove 2121 extend to the edges of the first active material layer 212 along the width direction Y of the first current collector, and there is a distance between both ends of the second groove 2122 and both ends of the first active material layer 212 along the width direction Y of the first current collector.

[0167] That is, along the width direction Y of the first current collector, neither end of the second groove 2122 extends to both ends of the first active material layer 212.

[0168] As Figure 9 shown, if both ends of the first groove 2121 extend to both ends of the first active material layer along the width direction Y of the first current collector, then the groove side surface of the first groove 2121 is a non-closed structure circumferentially along the groove bottom surface of the first groove 2121. When measuring the volume of the first groove 2121, at both ends of the first groove 2121 along the width direction Y of the first current collector, a virtual surface that is flush and coplanar with the two edges of the first active material layer 212 in the width direction Y of the first current collector is constructed, and the virtual surface and the groove side surface of the first groove 2121 together form a first closed surface that is circumferentially closed along the groove bottom surface of the first groove 2121.

[0169] Along the width direction Y of the first current collector, both ends of the first groove 2121 extend to the edges of the first active material layer 212, such that the size of the first groove 2121 in the width direction Y of the first current collector is larger, which is conducive to increasing the volume of the first groove 2121, enabling more electrolyte to be accommodated in the first groove 2121, thereby facilitating the full wetting of the first electrode sheet 21 by the electrolyte, and thus being conducive to improving the cycling performance and safety performance of the battery cell 100. The second groove 2122 has a distance from both ends of the first active material layer 212, that is, the second groove 2122 does not extend to both ends of the first active material layer 212 along the width direction Y of the first current collector. Then, along the width direction Y of the first current collector, the strength of the edge region of the first electrode sheet 21 is better, reducing the risk of wrinkling and curling of the edge region of the first electrode sheet 21 in the width direction, thereby reducing the risk of problems such as lithium deposition and short circuit in the battery cell 100 caused by the wrinkling of the first electrode sheet 21, and improving the safety performance of the battery cell 100. Since the second groove 2122 has a distance from both ends of the first active material layer 212 along the width direction Y of the first current collector, in the case where the first electrode sheet 21 and the separator 23 need to be connected, the region 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 a connection space for connecting the separator 23 to the first electrode sheet 21, can provide a relatively large connection area for connecting the first active material layer 212 and the separator 23, facilitating the connection between the first electrode sheet 21 and the separator 23 and being conducive to improving the connection stability between the first electrode sheet 21 and the separator 23, reducing the risk of curling and wrinkling of the edge regions of the first electrode sheet 21 and the separator 23, thereby reducing the risk of problems such as lithium deposition and short circuit in the battery cell 100 caused by the wrinkling and curling of the first electrode sheet 21 and the separator 23, and improving the safety performance of the battery cell 100.

[0170] As Figures 2 - 9 shown, in some embodiments, the first groove 2121 does not extend to the edges of the first active material layer 212 along the length direction Z of the first current collector, that is, when the first electrode sheet 21 is in the unfolded state, viewed along the thickness direction X of the first current collector, both ends of the first groove 2121 have a distance from both ends of the first active material layer 212 along the length direction Z of the first current collector.

[0171] The second groove 2122 does not extend to the edges of the first active material layer along the length direction of the first current collector, that is, when the first electrode sheet 21 is in the unfolded state, viewed along the thickness direction X of the first current collector, both ends of the second groove 2122 have a distance from both ends of the first active material layer 212 along the length direction Z of the first current collector.

[0172] 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.

[0173] As Figure 2 , Figure 4 , Figures 6 - 9 shown, 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 L 1 , and the size of the second groove 2122 is L 2 , where 0.85 ≤ L 1 / L ≤ 1, 0.81 ≤ L 2 / L ≤ 0.95.

[0174] L is 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. L 1 is 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. L 2 is 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 L 1 is only a characterization symbol for the size of the first groove 2121 in the width direction Y of the first current collector, and does not mean that the sizes of any two first grooves 2121 in the width direction Y of the first current collector are the same. It can be understood that along the width direction Y of the first current collector, the relationship between the size L 1 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 L 1 of any second groove 2122 and the width L of the first active material layer 212 satisfies 0.81 - 0.95.

[0175] Exemplarily, L 1 / L can be 0.85, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1, etc.

[0176] L 2 / 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.

[0177] By 0.85 ≤ L 1 / L, 0.81 ≤ L 2 / L such that both the first groove 2121 and the second groove 2122 have relatively large dimensions in the width direction Y of the first current collector, so that the volumes of the first groove 2121 and the second groove 2122 are both relatively large, enabling the first groove 2121 and the second groove 2122 to accommodate more electrolyte, which is beneficial to increasing the contact area between the electrolyte and the first active material layer 212, facilitating the full wetting of the first electrode sheet 21 by the electrolyte, and thus beneficial to improving the cycling performance and safety performance of the battery cell 100. By L 1 / L ≤ 1, L 2 / L ≤ 0.95 such that 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, which can reduce the loss of the first active material and the loss of the strength of the first electrode sheet 21 during the formation process of the first groove 2121 and the second groove 2122, and is beneficial for the battery cell 100 to have better energy density and mechanical properties. Therefore, 0.85 ≤ L 1 / L ≤ 1, 0.81 ≤ L 2 / L ≤ 0.95 is both beneficial to making the contact area between the first active material layer 212 and the electrolyte relatively large, facilitating the full wetting of the first electrode sheet 21 by the electrolyte, and thus beneficial to improving the cycling performance and safety performance of the battery cell 100, and can also reduce the loss of the active material and the loss of the strength of the first electrode sheet 21 during the formation process of the first groove 2121 and the second groove 2122.

[0178] In some embodiments, 75 mm ≤ L 1 ≤ 85 mm.

[0179] It can be understood that the dimension of any first groove 2121 in the width direction Y of the first current collector satisfies 75 mm to 85 mm.

[0180] Exemplarily, L 1 can be 75 mm, 76 mm, 77 mm, 78 mm, 79 mm, 80 mm, 81 mm, 82 mm, 83 mm, 84 mm, 85 mm, etc.

[0181] In some embodiments, 60 mm ≤ L 2 ≤ 80 mm.

[0182] It can be understood that the dimension of any second groove 2122 in the width direction Y of the first current collector satisfies 60 mm to 80 mm.

[0183] Exemplarily, L 2 can be 60 mm, 62 mm, 64 mm, 66 mm, 68 mm, 70 mm, 72 mm, 74 mm, 76 mm, 78 mm, 80 mm, etc.

[0184] By 75 mm ≤ L 1, 60mm ≤ L 2 , such that both the first groove 2121 and the second groove 2122 have relatively large dimensions in the width direction Y of the first current collector, so that both the first groove 2121 and the second groove 2122 have larger volumes, so that the first groove 2121 and the second groove 2122 can accommodate more electrolyte, thereby facilitating an increase in the contact area between the first active material layer 212 and the electrolyte, facilitating the first electrode sheet 21 to be fully wetted by the electrolyte, and thus facilitating an improvement in the cycle performance and safety performance of the battery cell 100. By L 1 ≤ 85mm, L 2 ≤ 80mm, controlling the dimensions of the first groove 2121 and the second groove 2122 in the width direction Y of the first current collector within a reasonable range can reduce the loss of the first active material and the strength loss of the first electrode sheet 21 during the formation of the first groove 2121 and the second groove 2122, which is beneficial for the battery cell 100 to have better energy density and mechanical properties. Therefore, 75mm ≤ L 1 ≤ 85mm, 60mm ≤ L 2 ≤ 80mm, that is, it is beneficial to make the contact area between the first active material layer 212 and the electrolyte relatively large, beneficial for the first electrode sheet 21 to be fully wetted by the electrolyte, thereby facilitating an improvement in the cycle performance and safety performance of the battery cell 100, and can further reduce the loss of active material during the formation of the first groove 2121 and the second groove 2122 and the strength loss of the first electrode sheet 21.

[0185] The depth of the first groove 2121 refers to the depth of the first groove 2121 from the surface of the first active material layer 212 facing away from the first current collector 211 towards the first current collector 211. The depth of the second groove 2122 refers to the depth of the second groove 2122 from the surface of the first active material layer 212 facing away from the first current collector 211 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, then the first current collector 211 at the corresponding positions of the first groove 2121 and the second groove 2122 is not exposed, which can not only avoid the exposure of the first current collector 211 at the corresponding positions of the first groove 2121 and the second groove 2122, reduce the risk of short circuit of the battery cell 100, but also reduce the loss of active material during the formation of the first groove 2121 and the second groove 2122, reduce the waste of active material and save costs.

[0186] The depth of the first groove 2121 and the depth of the second groove 2122 may be the same or different.

[0187] Such as Figure 3 、 Figure 5 shown, in some embodiments, the depth of the first groove 2121 is H 1 , 14μm ≤ H1 ≤ 20 μm.

[0188] H 1 is the dimension of the first groove 2121 that 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. H 1 is merely a representative symbol of the depth of the first groove 2121 and does not mean that the depths of any two first grooves 2121 are the same. It can be understood that the depth of any first groove 2121 satisfies 14 μm to 20 μm.

[0189] Exemplarily, H1 can be 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, etc.

[0190] In some embodiments, the depth of the second groove 2122 is H 2 , 14 μm ≤ H 2 ≤ 20 μm.

[0191] H 2 is the dimension of the second groove 2122 that 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. H 2 is merely a representative symbol of the depth of the second groove 2122 and does not mean that the depths of any two second grooves 2122 are the same. It can be understood that the depth of any second groove 2122 satisfies 14 μm to 20 μm.

[0192] Exemplarily, H2 can be 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, etc.

[0193] When 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, the depths of the first groove 2121 and the second groove 2122 are relatively large, so that the volumes of the first groove 2121 and the second groove 2122 are relatively large, and the contact area between the first active material layer 212 and the electrolyte is relatively large, which is conducive to the first pole piece 21 being fully wetted and improves the cycle performance of the battery cell 100. When 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, the loss of active material during the formation of the first groove 2121 and the second groove 2122 is reduced. If the first pole piece 21 is a positive pole piece, less loss of positive active material is conducive to improving the energy density. If the first pole piece 21 is a negative pole piece, less loss of negative active material is conducive to reducing the risk of lithium plating and improving the safety performance of the battery cell 100. Therefore, 14 μm ≤ H 1 ≤ 20 μm, 14 μm ≤ H 2 ≤ 20 μm, which is beneficial to improving the cycle performance of the battery cell 100 and reducing the loss of active material.

[0194] Furthermore, 15 μm ≤ H 1 ≤ 17 μm, 15 μm ≤ H 2 ≤ 17 μm.

[0195] That is, the depth of any first groove 2121 satisfies 15 μm to 17 μm, and the depth of any second groove 2122 satisfies 15 μm to 17 μm.

[0196] Exemplarily, H1 can be 15 μm, 15.1 μm, 15.2 μm, 15.3 μm, 15.4 μm, 15.6 μm, 15.7 μm, 15.8 μm, 15.9 μm, 16.1 μm, 16.2 μm, 16.3 μm, 16.4 μm, 16.6 μm, 16.7 μm, 16.8 μm, 16.9 μm, 17 μm, etc.

[0197] H2 can be 15 μm, 15.1 μm, 15.2 μm, 15.3 μm, 15.4 μm, 15.6 μm, 15.7 μm, 15.8 μm, 15.9 μm, 16.1 μm, 16.2 μm, 16.3 μm, 16.4 μm, 16.6 μm, 16.7 μm, 16.8 μm, 16.9 μm, 17 μm, etc.

[0198] By the depth of the first groove 2121 being greater than or equal to 15 μm and the depth of the second groove 2122 being greater than or equal to 15 μm, the depths of the first groove 2121 and the second groove 2122 are greater, such that the volumes of the first groove 2121 and the second groove 2122 are greater, such that the contact area between the first active material layer 212 and the electrolyte is greater, thereby facilitating the sufficient wetting of the first electrode tab 21 and further improving the cycling performance of the battery cell 100. By the depth of the first groove 2121 being less than or equal to 17 μm and the depth of the second groove 2122 being less than or equal to 17 μm, the loss of the active material during the forming process of the first groove 2121 and the second groove 2122 is reduced. If the first electrode tab 21 is a positive electrode tab, less loss of the positive active material is beneficial to improving the energy density. If the first electrode tab 21 is a negative electrode tab, less loss of the negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the battery cell 100. Therefore, 15 μm ≤ H1 ≤ 17 μm, 15 μm ≤ H2 ≤ 17 μm, which is beneficial to further improving the cycling performance of the battery cell 100 and can further reduce the loss of the active material.

[0199] In some embodiments, 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 first groove 2121 on the surface of the first active material layer 212 facing away from the first current collector 211.

[0200] 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 on the surface of the first active material layer 212 facing away from the first current collector 211 along the length direction Z of the first current collector. 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 on the surface of the first active material layer 212 facing away from the first current collector 211 along the length direction Z of the first current collector.

[0201] By 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 being greater than 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, the volume of the second groove 2122 can be made smaller than the volume of the first groove 2121 by reducing the dimensions of the second groove 2122 in other directions, thereby facilitating the processing and forming of the first groove 2121 and the second groove 2122.

[0202] Of course, in some other embodiments, 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 may be the same as 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, or 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 may be less than 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.

[0203] As Figures 2 - 9 shown, in some embodiments, 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 W 1 , 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 W 2 , 0.8 ≤ W 1 / W 2 ≤ 1.

[0204] W 1 / W 2 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.

[0205] By 0.8 ≤ W 1 / W 2 , 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, which is beneficial to the uniform infiltration of the first pole piece 21 and the uniform current distribution, reduces the risk of lithium deposition in the battery cell 100, and improves the safety performance of the battery cell 100. W 1 / W 2 ≤ 1 makes 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 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. The volume of the second groove 2122 can be made smaller than the volume of the first groove 2121 by reducing the dimensions of the second groove 2122 in other directions, thus facilitating the formation of the first groove 2121 and the second groove 2122. Therefore, 0.8 ≤ W 1 / W 2 ≤ 1 is both beneficial to improving the safety performance of the battery cell 100 and facilitating the processing and formation of the first groove 2121 and the second groove 2122.

[0206] In some embodiments, 60 μm ≤ W 1 ≤ 100 μm.

[0207] W 1 ​​​​​​​​​​It is only 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 the widths of any two first grooves 2121 on the surface of the first active material layer 212 facing away from the first current collector 211 are the same. 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 60 μm to 100 μm.

[0208] Exemplarily, W 1 can be 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, etc.

[0209] In some embodiments, 60 μm ≤ W 2 ≤ 100 μm.

[0210] W 2 It is only 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 the widths of any two second grooves 2122 on the surface of the first active material layer 212 facing away from the first current collector 211 are the same. 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 60 μm to 100 μm.

[0211] Exemplarily, W 2 can be 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, etc.

[0212] When 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 or equal to 60 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 greater than or equal to 60 μm, the first groove 2121 and the second groove 2122 have a relatively large width, so that the volumes of the first groove 2121 and the second groove 2122 are relatively large, so that a relatively large amount of electrolyte can be accommodated in both the first groove 2121 and the second groove 2122, so that the first active material layer 212 and the electrolyte have a relatively large contact area, which is conducive to the first pole piece 21 being fully wetted, improving the cycling performance of the battery cell 100. It also makes the notch width of the first groove 2121 and the notch width of the second groove 2122 relatively large, facilitating the entry of the electrolyte into the first groove 2121 and the second groove 2122. When 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 the active material during the forming process of the first groove 2121 and the second groove 2122 is reduced. If the first pole piece 21 is a positive pole piece, less loss of the positive active material is conducive to improving the energy density. If the first pole piece 21 is a negative pole piece, less loss of the negative active material is conducive to reducing the risk of lithium plating and improving the safety performance of the battery cell 100. Therefore, 60 μm ≤ W 1 ≤ 100 μm, 60 μm ≤ W 2 ≤ 100 μm, which is not only conducive to improving the cycling performance of the battery cell 100, but also can reduce the loss of the active material.

[0213] Further, 70 μm ≤ W 1 ≤ 80 μm, 70 μm ≤ W 2 ≤ 80 μm.

[0214] 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 70 μm to 80 μm. For example, W1 can be 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, etc.

[0215] 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 70 μm to 80 μm. W2 can be 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, etc.

[0216] When 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 or equal to 70 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 greater than or equal to 70 μm, the first groove 2121 and the second groove 2122 have a larger width, so that the volumes of the first groove 2121 and the second groove 2122 are larger, so that more electrolyte can be accommodated in both the first groove 2121 and the second groove 2122, so that the first active material layer 212 and the electrolyte have a larger contact area, which is further conducive to the first pole piece 21 being fully wetted and further improving the cycle performance of the battery cell 100. It also makes the notch width of the first groove 2121 and the notch width of the second groove 2122 larger, facilitating the entry of the electrolyte into the first groove 2121 and the second groove 2122. When 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 less than or equal to 80 μm, the loss of the active material during the forming process of the first groove 2121 and the second groove 2122 is further reduced. If the first pole piece 21 is a positive pole piece, less loss of the positive active material is beneficial to improving the energy density. If the first pole piece 21 is a negative pole piece, less loss of the negative active material is beneficial to reducing the risk of lithium plating and improving the safety performance of the battery cell 100. Therefore, 70 μm ≤ W 1 ≤ 80 μm, 70 μm ≤ W 2 ≤ 80 μm, which is beneficial to further improving the cycle performance of the battery cell 100 and can further reduce the loss of the active material.

[0217] In some embodiments, the first pole piece 21 is a negative pole piece.

[0218] If the first electrode tab 21 is a negative electrode tab, by providing a first groove 2121 and a second groove 2122 in the active material layer of the negative electrode tab, the contact area between the negative active material layer and the electrolyte can be increased, which is beneficial for the negative electrode tab to be fully wetted by the electrolyte, reducing the risk of lithium plating, and thus conducive to improving the cycling performance and safety performance of the battery cell 100. The volume of the first groove 2121 is larger than that of the second groove 2122. Compared with only providing the first groove 2121 with a larger volume on the negative active material layer, this solution can reduce the loss of negative active material and the strength loss of the first electrode tab 21, reduce the risk of lithium plating, and is beneficial for the battery cell 100 to have better energy density and mechanical properties. Compared with only providing the second groove 2122 with a smaller volume on the negative active material layer, this solution can provide a larger contact area between the negative active material layer and the electrolyte, facilitating the full wetting of the negative electrode tab by the electrolyte, thereby improving the wetting performance of the battery cell 100. Therefore, this solution can increase the contact area between the negative active material layer and the electrolyte while losing less active material, improve the wetting performance, and thus improve the cycling 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 negative active material layer and the electrolyte by losing less active material, improve the wetting performance, enabling the battery cell 100 to have a higher energy density and a higher safety performance.

[0219] As Figure 10 , Figure 11 shown, in some embodiments, the electrode assembly 20 further includes a second electrode tab 22. The first electrode tab 21 and the second electrode tab 22 have opposite polarities. The second electrode tab 22 includes a second current collector 221 and a second active material layer 222. Along the thickness direction of the second electrode tab 22, the second active material layer 222 is provided on at least one side of the second current collector 221; when observing 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 in 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.

[0220] In the embodiment where the first electrode tab 21 is a negative electrode tab, the second electrode tab 22 is a positive electrode tab.

[0221] Along the width direction Y of the first current collector, both ends of the first active material layer 212 extend beyond those 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 part 2125 and a second part 2126 that extend beyond the second active material layer 222, and the first part 2125 and the second part 2126 are respectively located on both 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. The first region 21213 is located in the first part 2125, and the second region 21214 is located in the second part 2126, so that the first groove 2121 extends beyond both ends of the second active material layer 222. A part of the second groove 2122 is located in the first part 2125, and the other part of the first groove 2121 is located in the second part 2126, so that the second groove 2122 extends beyond both ends of the second active material layer 222.

[0222] Both ends of the second groove 2122 along the width direction Y of the first current collector may be flush with both ends of the second active material layer 222 along the width direction Y of the first current collector, or along the width direction Y of the first current collector, the second active material layer 222 extends beyond both 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 both ends of the second active material layer 222 along the width direction Y of the first current collector. Figure 11 The situation where the second active material layer 222 extends beyond both ends of the second groove 2122 along the width direction Y of the first current collector is shown.

[0223] By making the first groove 2121 extend beyond both ends of the second active material layer 222 and the second groove 2122 not extend beyond both ends of the second active material layer 222 along the width direction Y of the first current collector, the part of the first active material layer 212 that extends beyond the second active material layer 222 can have better wettability, which is beneficial to improving the cycling performance of the battery cell 100. 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 is beneficial to ensuring the strength of the part of the first electrode tab 21 that extends beyond the second active material layer 222 along the width direction Y of the first current collector, reducing the risk of curling of the first electrode tab 21, and thus reducing the risk of problems such as lithium plating and short circuit of the battery cell 100 caused by wrinkling and curling of the first electrode tab 21 and the separator 23, and improving the safety performance of the battery cell 100.

[0224] As Figure 10 、 Figure 12 shown, 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 G 1The minimum distance between any end of the second groove 2122 and the end of the second active material layer 222 is G 2 , 0.2 mm ≤ G 1 ≤ 1 mm, 0.2 mm ≤ G 2 ≤ 1 mm.

[0225] 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 first groove 2121 in the region of the first part 2125 along the width direction Y of the first current collector or the dimension of the first groove 2121 in the region of the second part 2126 along the width direction Y of the first current collector.

[0226] The dimension of the region (the first region 21213) of the first groove 2121 in the first part 2125 along the width direction Y of the first current collector satisfies 0.2 mm to 1 mm. The dimension of the region (the second region 21214) of the first groove 2121 in the second part 2126 along the width direction Y of the first current collector satisfies 0.2 mm to 1 mm.

[0227] Exemplarily, G 1 can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0228] 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 of the end of the second groove 2122 close to the first part 2125 and the end of the second active material layer 222 close to the first part 2125 along the width direction Y of the first current collector or the dimension of the end of the second groove 2122 close to the second part 2126 and the end of the second active material layer 222 close to the second part 2126 along the width direction Y of the first current collector.

[0229] The dimension of the end of the second groove 2122 close to the first part 2125 and the end of the second active material layer 222 close to the first part 2125 along the width direction Y of the first current collector satisfies 0.2 mm to 1 mm. The dimension of the end of the second groove 2122 close to the second part 2126 and the end of the second active material layer close to the second part 2126 along the width direction Y of the first current collector satisfies 0.2 mm to 1 mm.

[0230] Exemplarily, G 2 can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0231] By 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 greater than or equal to 0.2 mm. The volume of the first groove 2121 in the part where the first active material layer 212 extends beyond the second active material layer 222 is relatively large, which is beneficial to improving the wetting of the first electrode sheet 21 and enhancing the cycling performance of the battery cell 100. By 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 less than or equal to 1 mm, which is beneficial to reducing the loss of active material during the forming process of the first groove 2121 and increasing the energy density of the battery cell 100. Therefore, 0.2 mm ≤ G 1 ≤ 1 mm can not only improve the wetting effect of the first electrode sheet 21 and enhance the cycling performance of the battery cell 100, but also reduce the loss of active material and increase the energy density of the battery cell 100. Since both ends of the second groove 2122 do not extend beyond both ends of the second active material layer 222 in the width direction Y of the first current collector, by 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 is greater than or equal to 0.2 mm, which is beneficial to reducing the loss of active material during the forming process of the second groove 2122 and increasing the energy density of the battery cell, and making the strength of the edge region of the first electrode sheet 21 in the width direction Y of the first current collector better, reducing the risk of curling of the first electrode sheet 21. 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 in the width direction Y of the first current collector relatively large and the volume of the second groove 2122 relatively large, which is beneficial to improving the wetting of the first electrode sheet 21 and enhancing the cycling performance of the battery cell 100. Therefore, 0.2 mm ≤ G 2 ≤ 1 mm can not only improve the wetting effect of the first electrode sheet 21 and enhance the cycling performance of the battery cell 100, but also reduce the loss of active material and increase the energy density of the battery cell 100.

[0232] As Figures 12 - 15 shown, among all the first grooves 2121 and the second grooves, in the length direction Z of the first current collector, at least one of the two farthest apart can extend to the edge of the first active material layer 212 in the length direction Z of the first current collector.

[0233] Among them, among all the first grooves 2121 and the second grooves, in the length direction Z of the first current collector, the two farthest apart can be two first grooves 2121, or two second grooves 2122, or one is a first groove 2121 and the other is a second groove 2122. Figure 12 、 Figure 13Among all the first grooves 2121 and second grooves, in the length direction Z of the first current collector, the two that are farthest apart are two first grooves 2121, and both of the two that are farthest apart extend to the edge of the first active material layer 212 in the length direction Z of the first current collector. Figure 12 , Figure 13 In, for the two first grooves 2121 that extend to the edge of the first active material layer 212 in the length direction Z of the first current collector and 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, it is necessary to construct virtual planes flush with the edge of the first active material layer 212 in the width direction Y of the first current collector at both ends of the first groove 2121 along the width direction Y of the first current collector, and construct a virtual plane flush with the edge of the first active material layer 212 in the width direction Y of the first current collector on the side where the first groove 2121 extends to the edge of the first active material layer 212 in the length direction Z of the first current collector. All the virtual planes and the groove 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.

[0234] Figure 14 , Figure 15 Among all the second grooves 2122, in the length direction Z of the first current collector, the two that are farthest apart are two second grooves 2122, and both of the two that are farthest apart extend to the edge of the first active material layer 212 in the length direction Z of the first current collector. Figure 14 , Figure 15 In, for the two second grooves 2122 that extend to the edge of the first active material layer 212 in the length direction Z of the first current collector but do not 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 second groove 2122, it is only necessary to construct a virtual plane flush with the edge of the first active material layer 212 in the width direction Y of the first current collector on the side where the second groove 2122 extends to the edge of the first active material layer 212 in the length direction Z of the first current collector. The virtual plane and the groove side surface of the second groove 2122 together form a second closed surface that is circumferentially closed along the bottom surface of the second groove 2122.

[0235] The embodiment of the present application also provides an electrical device, and the electrical device includes the battery cell 100 provided in any of the above embodiments.

[0236] The battery cell 100 provides electrical energy for the operation of the electrical device. The battery cell 100 provided in any of the above embodiments has good safety performance and cycling performance, which is beneficial to improving the electrical safety and electrical reliability of the electrical device powered by the battery cell 100.

[0237] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and variations can be made to the present application.

Claims

1. A battery cell, characterized in that: include: An electrode assembly, comprising a first pole piece, wherein the first pole piece comprises a first current collector and a first active material layer, and along a thickness direction of the first current collector, at least one side of the first current collector is provided with the first active material layer; Among them, a first groove and a second groove are arranged at intervals on the surface of at least one of the first active material layers facing away from the first current collector, the first groove and the second groove are arranged at intervals along the length direction of the first current collector, and the volume of the first groove is greater than that of the second groove.

2. The battery cell according to claim 1, characterized in that: 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, characterized in that: Along a width direction of the first current collector, a size of the first groove is greater than a size of the second groove.

4. The battery cell according to claim 3, characterized in that: Observed along the thickness direction of the first current collector, the first groove has a distance from two opposite ends of the first active material layer along the width direction of the first current collector, and the second groove has a distance from two opposite ends of the first active material layer along the width direction of the first current collector.

5. The battery cell according to claim 3, characterized in that: When viewed along the thickness direction of the first current collector, at least one end of the first groove extends to an edge of the first active material layer along the width direction of the first current collector.

6. The battery cell according to claim 5, characterized in that: Observed 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 distanced from both ends of the first active material layer along the width direction of the first current collector.

7. The battery cell according to claim 1, characterized in that: The first active material layer is provided with a plurality of the first grooves and a plurality of the second grooves, and the first grooves and the second grooves are alternately arranged along the length direction of the first current collector.

8. The battery cell according to claim 7, characterized in that: A distance between any adjacent first grooves and second grooves on a surface of the first active material layer facing away from the first current collector is W, and 0.9 μm≤W≤2.5 μm.

9. The battery cell according to claim 1, characterized in that: 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, characterized in that: 75mm≤L1≤85mm, 60mm≤L2≤80mm.

11. The battery cell according to claim 1, characterized in that: A plurality of first grooves are arranged on the surface of the first active material layer, and 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, and 1.8 μm≤K1≤5 μm.

12. The battery cell according to claim 1, characterized in that: A plurality of second grooves are provided on the surface of the first active material layer, and 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, and 1.8 μm≤K2≤5 μm.

13. The battery cell according to claim 1, characterized in that: 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, 14 μm≤H1≤20 μm, and the depth of the second groove is H2, 14 μm≤H2≤20 μm.

14. The battery cell according to any one of claims 1 to 13, characterized in that: A width of the second groove on a surface of the first active material layer facing away from the first current collector is greater than a width of the first groove on a surface of the first active material layer facing away from the first current collector.

15. The battery cell according to any one of claims 1 to 13, characterized in that: 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 W 2， 0.8≤W1 / W2≤1.

16. The battery cell according to claim 15, characterized in that: 60μm≤W1≤100μm, 60μm≤W2≤100μm.

17. The battery cell according to any one of claims 1 to 13, characterized in that: The electrode assembly further includes a second pole piece, the first pole piece and the second pole piece have opposite polarities, the second pole piece 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 pole piece; When viewed along the thickness direction of the first current collector, the first groove exceeds two ends of the second active material layer along the width direction of the first current collector, and the second groove does not exceed two ends of the second active material layer.

18. The battery cell according to claim 17, characterized in that: 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, 0.2mm≤G1≤1mm, 0.2mm≤G2≤1mm.

19. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-18.

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