Battery cell and electric device

Abstract

Provided in the present application are a battery cell and an electric device comprising the battery cell. A first electrode sheet 23 of the battery cell comprises a first electrode sheet segment 231; the first electrode sheet segment 231 comprises a first current collector 2311, a first active material layer 2312, and a second active material layer 2313, wherein the first current collector has a first surface 23111 and a second surface 23112 arranged opposite each other, the first active material layer 2312 being disposed on the first surface 23111, and the second active material layer 2313 being disposed on the second surface 23112; the first surface 23111 has a first bare foil region Q1; the first active material layer 2312 is provided with a first tab accommodating groove 23121 that exposes the first bare foil region Q1, and the second active material layer 2313 is disposed in the area of the second surface 23112 opposite the first tab accommodating groove 23121. A first tab 30 of the battery cell has a first portion 31 accommodated in the first tab accommodating groove 23121 and welded to form a first weld mark Q. A second electrode sheet 24 of the battery cell comprises a second electrode sheet segment 241, the second electrode sheet segment 241 being arranged opposite to and facing the first electrode sheet segment 231 in a first direction. When viewed in the first direction, a first insulating member 40 covers the first weld mark Q. The first insulating member 40 can insulate and separate the area of the second active material layer 2313 corresponding to the first weld mark Q from the second electrode sheet segment 241, thereby preventing metal ions from depositing on the negative electrode surface, reducing the risk of lithium plating in the battery cell, and improving the safety performance of the battery cell.

Description

Battery cell and electric device Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application No. 202411389234X, filed on September 30, 2024, entitled "Battery cell and electric device", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery cell and an electric device. BACKGROUND

[0003] With the rapid development of new energy technology, battery cells have been widely used in electronic devices, electric vehicles, electric two-wheel vehicles, electric tools and other fields. As the application of battery cells becomes more and more widespread, higher requirements are placed on the safety of battery cells. SUMMARY

[0004] Embodiments of the present application provide a battery cell and an electric device to improve the safety performance of the battery cell.

[0005] In a first aspect, embodiments of the present application provide a battery cell, including a first pole piece, a first tab, a second pole piece and a first insulating piece. The first pole piece includes a first pole piece segment, and the first pole piece segment includes a first current collector, a first active material layer and a second active material layer. The first current collector has a first surface and a second surface oppositely arranged along a first direction, the first active material layer is arranged on the first surface, and the second active material layer is arranged on the second surface. The first surface has a first empty foil area, the first active material layer is provided with a first tab receiving groove exposing the first empty foil area, and the second surface is provided with the second active material layer opposite the first tab receiving groove. The first tab is partially received in the first tab receiving groove, and the first tab has a first portion overlapping the first empty foil area, and the first portion is welded with the first empty foil area to form a first welding mark. The second pole piece is opposite in polarity to the first pole piece, and the second pole piece includes a second pole piece segment, the second pole piece segment is arranged opposite to the first pole piece segment and facing the second surface along the first direction, and the second pole piece includes a second current collector. The first insulating piece is arranged between the second active material layer and the second current collector of the second pole piece segment, and the first insulating piece covers the first welding mark as viewed along the first direction.

[0006] In the one or more optional embodiments above, the first tab segment is only formed with the first empty foil area on the first surface, and the area corresponding to the first empty foil area on the second surface is covered by the second active material layer, so that the first tab can be formed with the first tab receiving groove on only one side of the first tab segment, simplifying the processing process of the first tab, reducing the waste of active material and capacity loss, and thus facilitating the energy density of the battery cell. During the process of welding the first part with the first empty foil area to form the first welding mark, the bonding network and the conductive network of the part of the second active material layer corresponding to the first welding mark can be damaged, resulting in the metal ions of the positive electrode not returning to the positive electrode or not being embedded in the negative electrode, thus causing lithium precipitation on the surface of the negative electrode and further causing the battery cell to precipitate lithium. The first insulating member is arranged between the second active material layer and the second current collector of the second tab segment, and the first insulating member covers the first welding mark when viewed in the first direction. The first insulating member can insulate and separate the area of the second active material layer corresponding to the first welding mark and the second tab segment, so as to prevent the metal ions from precipitating on the surface of the negative electrode, reduce the risk of lithium precipitation of the battery cell, and improve the safety performance of the battery cell.

[0007] In some embodiments of the first aspect of the application, along the length direction of the first tab segment, the size of the first insulating member is W1, the size of the first welding mark is W'3, and the size of the first tab receiving groove is K. Along the width direction of the first tab segment, the size of the first insulating member is L1, the size of the first welding mark is L'3, and the size of the first tab receiving groove is G. W'3 < W1 < K, L'3 < L1 < G.

[0008] In the one or more optional embodiments above, since the first part is welded with the first empty foil area, the heat generated by welding can easily cause the active material on the back surface opposite to the welding mark to be deactivated, resulting in lithium precipitation. Therefore, the size of the first insulating member needs to satisfy W'3 < W 1， L'2 < L1, and if the size of the first insulating member is equal to the size of the first tab receiving groove, the active material that is not deactivated by welding will be covered, resulting in a loss of energy density. When the size of the first insulating member is greater than the size of the first tab receiving groove, the excess part of the adhesive paper will cause the thickness of the tab to be relatively thick, and when the size of the first insulating member is smaller than the size of the tab receiving groove, the thickness of the first insulating member will be partially balanced with the depth of the first tab receiving groove. Therefore, W1 < K and L1 < G are limited.

[0009] In some embodiments of the first aspect of the application, along the length direction of the first tab segment, the size of the first part is W3, and along the width direction of the first tab segment, the size of the first part is L3. W3 < W1 and L3 < L1.

[0010] In one or more optional embodiments of the above, W3 < W1, L3 < L1, so that the first insulating member can completely cover the second active material layer in the region corresponding to the first portion as viewed in the first direction, further reducing the risk of lithium precipitation on the negative electrode surface due to the positive electrode not being able to return to the positive electrode or not being able to embed the metal ions of the negative electrode during the formation of the first weld, and improving the safety performance of the battery cell.

[0011] In some embodiments of the first aspect of the application, one of the first and second electrode tabs is a positive electrode tab, and the first insulating member is disposed on the positive electrode tab.

[0012] In one or more optional embodiments of the above, the first insulating member is disposed on the positive electrode tab, which can prevent metal ions in the region of the positive electrode tab corresponding to the first weld from precipitating from the positive electrode tab, thereby better reducing the risk of lithium precipitation on the battery cell and improving the safety performance of the battery cell.

[0013] In some embodiments of the first aspect of the application, the first electrode tab is a positive electrode tab, and the second active material layer has a first accommodating groove disposed on the surface facing the second electrode tab segment, and the first insulating member is at least partially disposed in the first accommodating groove.

[0014] In one or more optional embodiments of the above, by providing the first accommodating groove in the second active material layer and at least partially disposing the first insulating member in the first accommodating groove, not only is the first insulating member convenient to set, but also the first insulating member and the first electrode tab segment overlap in space, which can reduce the size of the battery cell in the thickness direction of the first insulating member, reduce the impact of the first insulating member on the energy density of the battery cell, and reduce the size difference between the parts of the battery cell, thereby alleviating the uneven stress on the electrode tab, the deterioration of the contact interface, and the appearance of black spots or even lithium precipitation in the interface after cycling, and also allowing the battery cell to have a high energy density and improving the safety performance of the battery cell.

[0015] In some embodiments of the first aspect of the application, the depth of the first accommodating groove is less than the thickness of the second active material layer.

[0016] In one or more optional embodiments of the above, the depth of the first accommodating groove is less than the thickness of the second active material layer, which can reduce the loss of the second active material in the second accommodating groove.

[0017] In some embodiments of the first aspect of the application, in the length direction of the first electrode tab segment, the size of the first insulating member is W1, and the size of the first accommodating groove is W2; in the width direction of the first electrode tab segment, the size of the first insulating member is L1, and the size of the first accommodating groove is L2; 0.1 mm ≤ W2-W1 ≤ 2 mm, and 0.1 mm ≤ L2-L1 ≤ 2 mm.

[0018] In one or more optional embodiments of the above, W2-W1≥0.1 mm, L2-L1≥0.1 mm, not only facilitating the installation of the first insulating member, but also reserving space for the expansion of the first insulating member and the active material layer during the circulation of the battery cell, relieving the problem of the active material layer and the first insulating member being extruded due to the expansion of the tab during the circulation of the battery cell, being conducive to improving the stability of the first insulating member, and further improving the safety performance of the battery cell. W2-W1≤2 mm, L2-L1≤2 mm, reducing space waste, being conducive to the battery cell having a high energy density, and also enabling the area of the region of the bottom wall of the first accommodating groove that is not covered by the first insulating member to be reduced, reducing the risk of lithium precipitation, and further improving the safety performance of the battery cell.

[0019] In some embodiments of the first aspect of the application, the second tab is a positive electrode tab, the second tab segment includes a second current collector and a third active material layer, and the third active material layer is arranged on the surface of the second current collector facing the first tab segment; the surface of the third active material layer facing the first tab segment is provided with a first accommodating groove, and the first insulating member is at least partially arranged in the first accommodating groove.

[0020] In one or more optional embodiments of the above, by arranging the first accommodating groove on the third active material layer and arranging the first insulating member in the first accommodating groove, not only is the arrangement of the first insulating member facilitated, but also the first insulating member and the second tab segment overlap in space, which can reduce the size of the battery cell in the thickness direction of the first insulating member, reduce the impact of the arrangement of the first insulating member on the energy density of the battery cell, and reduce the size difference between the parts of the battery cell, thereby relieving the situation of uneven surface of the battery cell caused by the arrangement of the first insulating member, relieving the problems of uneven stress on the tab, poor contact interface, and black spots or even lithium precipitation on the interface after circulation, and also enabling the battery cell to have a high energy density and improving the safety performance of the battery cell.

[0021] In some embodiments of the first aspect of the application, the depth of the first accommodating groove is less than the thickness of the third active material layer.

[0022] In one or more optional embodiments of the above, the depth of the first accommodating groove is less than the thickness of the third active material layer, which can reduce the loss of active material when the first accommodating groove is opened on the third active material layer.

[0023] In some embodiments of the first aspect of the application, along the length direction of the second tab segment, the size of the first insulating member is W1, and the size of the first accommodating groove is W2; along the width direction of the second tab segment, the size of the first insulating member is L1, and the size of the first accommodating groove is L2; 0.1 mm≤W2-W1≤4 mm, and 0.1 mm≤L2-L1≤3 mm.

[0024] In one or more optional embodiments of the above, W2-W1≥0.1 mm and L2-L1≥0.1 mm, not only facilitating the installation of the first insulating member, but also reserving space for the expansion of the first insulating member and the active material layer during the circulation of the battery cell, relieving the problem of the active material layer and the first insulating member being extruded due to the expansion of the tab during the circulation of the battery cell, being conducive to improving the stability of the first insulating member, and further improving the safety performance of the battery cell. W2-W1≤4 mm and L2-L1≤3 mm, reducing space waste, being conducive to the battery cell having a higher energy density, and also enabling the area of the region of the bottom wall of the first accommodating groove that is not covered by the first insulating member to be reduced, reducing the risk of lithium precipitation, and further improving the safety performance of the battery cell.

[0025] In some embodiments of the first aspect of the application, the depth of the first accommodating groove is greater than or equal to the thickness of the first insulating member.

[0026] In one or more optional embodiments of the above, the depth of the first accommodating groove is greater than or equal to the thickness of the first insulating member, so that the first insulating member can be completely accommodated in the first accommodating groove in the thickness direction of the first insulating member, avoiding the first insulating member extending out of the first accommodating groove in the thickness direction of the first insulating member, thereby avoiding the size of the battery cell in the thickness direction of the first insulating member being increased due to the arrangement of the first insulating member, reducing the loss of energy density of the battery cell due to the arrangement of the first insulating member, and enabling the battery cell to have a better energy density.

[0027] In some embodiments of the first aspect of the application, the depth of the first accommodating groove is T1, the thickness of the first insulating member is C1, and 0.1 μm≤T1-C1≤10 μm.

[0028] In one or more optional embodiments of the above, 0.1 μm≤T1-C1, so that the first insulating member does not protrude from the surface of the active material layer away from the current collector, avoiding the size of the battery cell in the thickness direction of the first insulating member being increased due to the arrangement of the first insulating member, reducing the influence of the energy density of the battery cell due to the arrangement of the first insulating member and reducing the size difference of each part of the battery cell, relieving the situation of the surface of the battery cell being uneven due to the arrangement of the first insulating member, thereby relieving the problems of uneven stress on the tab, poor contact interface, and black spots or even lithium precipitation in the interface after circulation, also enabling the battery cell to have a higher energy density, and further improving the safety performance of the battery cell. T1-C1≤10 μm, reducing space waste, and being conducive to the battery cell having a higher energy density.

[0029] In some embodiments of the first aspect of the application, the first tab is a positive tab, along the length direction of the first tab segment, the size of the first welding mark is W'3, and the size of the first insulating piece is W1; along the width direction of the first tab segment, the size of the first welding mark is L'3, and the size of the first insulating piece is L1; 0.1mm≤W1-W'3≤3mm, and 0.1mm≤L1-L'3≤3mm.

[0030] In one or more optional embodiments above, 0.1mm≤W1-W'3, and 0.1mm≤L1-L'3. Since the heat of welding spreads, the area affected by welding is slightly larger than the welding area, about 0.1mm. Therefore, the width and length of the first insulating piece need to exceed the welding mark by 0.1mm, so that the first insulating piece can completely cover the deactivated active material, better prevent the metal ions in the area of the positive tab corresponding to the first welding mark from being precipitated, reduce the risk of lithium precipitation of the battery cell, and improve the safety performance of the battery cell. W1-W'3≤3mm and L1-L'3≤3mm reduce the space occupied by the first insulating piece, thereby reducing the capacity loss of the battery cell, and thus facilitating the battery cell to have a higher energy density.

[0031] In some embodiments of the first aspect of the application, the first tab is a negative tab, along the length direction of the first tab segment, the size of the first welding mark is W'3, and the size of the first insulating piece is W1; along the width direction of the first tab segment, the size of the first welding mark is L'3, and the size of the first insulating piece is L1; 0.1mm≤W1-W'3≤5mm, and 0.1mm≤L1-L'3≤3mm.

[0032] In one or more optional embodiments above, 0.1mm≤W1-W'3, and 0.1mm≤L1-L'3. Since the area affected by welding is slightly larger than the welding area, about 0.1mm. Therefore, the width and length of the first insulating piece need to exceed the welding mark by 0.1mm, so that the first insulating piece can completely cover the deactivated active material, better prevent the metal ions in the area of the positive tab corresponding to the first welding mark from being precipitated, reduce the risk of lithium precipitation of the battery cell, and improve the safety performance of the battery cell. W1-W'3≤5mm and L1-L'3≤3mm reduce the space occupied by the first insulating piece, thereby reducing the capacity loss of the battery cell, and thus facilitating the battery cell to have a higher energy density.

[0033] In some embodiments of the first aspect of the application, the second tab further comprises a third tab segment, and the first tab segment is located between the second tab segment and the third tab segment; the third tab segment comprises a third current collector and a fourth active material layer, the fourth active material layer is arranged on the surface of the third current collector facing the first tab segment, the surface of the fourth active material layer facing the first tab segment is provided with a second accommodating groove, and the projection of the first part and the projection of the first insulating piece are both located in the second accommodating groove when viewed along the first direction.

[0034] In one or more optional embodiments of the above, by arranging the second accommodating groove in the fourth active material layer, and by observing in the first direction, the projection of the first portion and the projection of the first insulating member are both located in the second accommodating groove, the size of the battery cell in the thickness direction of the first insulating member can be reduced, the influence of the arrangement of the first insulating member on the energy density of the battery cell is reduced, and the size difference of the battery cell is reduced, so as to alleviate the surface unevenness of the battery cell caused by the arrangement of the first insulating member, thereby alleviating the problems of uneven stress on the tab, poor contact interface, and black spots or even lithium precipitation on the interface after cycling, and improving the safety performance of the battery cell.

[0035] In some embodiments of the first aspect of the application, along the length direction of the first tab segment, the size of the first insulating member is W1, and the size of the second accommodating groove is W4; along the width direction of the first tab segment, the size of the first insulating member is L1, and the size of the second accommodating groove is L4; 0.1mm≤W4-W1≤6mm, and 0.1mm≤L4-L1≤5mm.

[0036] In one or more optional embodiments of the above, 0.1mm≤W4-W1, and 0.1mm≤L4-L1. Not only can the first insulating member be completely embedded in the second accommodating groove in the length direction of the first tab segment and the width direction of the first tab segment, but also space is reserved for the expansion of the first insulating member and the active material layer during the cycling of the battery cell, thereby alleviating the problem of the active material layer and the first insulating member being squeezed due to the expansion of the tab during the cycling of the battery cell, which is conducive to improving the stability of the first insulating member and further improving the safety performance of the battery cell. W4-W1≤6mm and L4-L1≤5mm reduce the waste of space and the loss of the third active material, which is conducive to the battery cell having a high energy density.

[0037] In some embodiments of the first aspect of the application, the battery cell further comprises a second insulating member, the second insulating member is at least partially accommodated in the second accommodating groove, and the second insulating member covers the first welding mark when observed in the first direction.

[0038] In one or more optional embodiments of the above, the battery cell includes a second insulating piece disposed in the second accommodating groove of the third tab segment, the second insulating piece being capable of separating the first portion and the third tab segment, and reducing the risk of the burr of the first welding mark piercing the separator and causing short circuit. In the embodiment where the second tab is a positive tab, the second insulating piece can also prevent the precipitation of metal ions at the position corresponding to the first empty foil area of the positive tab, reducing the risk of lithium precipitation of the battery cell and improving the safety performance of the battery cell. The second insulating piece is disposed in the second accommodating groove of the third tab segment, which not only facilitates the arrangement of the second insulating piece, but also makes the second insulating piece and the third tab segment overlap in space, thereby reducing the size of the battery cell in the thickness direction of the second insulating piece, reducing the impact of the arrangement of the second insulating piece on the energy density of the battery cell and reducing the size difference between the parts of the battery cell, to alleviate the uneven stress on the tab, the deterioration of the contact interface, and the black spots and even lithium precipitation at the interface after cycling. In addition, the battery cell has a high energy density and improved safety performance.

[0039] In some embodiments of the first aspect, the second accommodating groove includes a first groove segment and a second groove segment, the first groove segment being closer to the third current collector than the second groove segment, a groove side surface of the first groove segment and a groove side surface of the second groove segment being connected by a first step surface, the second insulating piece being at least partially accommodated in the second groove segment and connected to the first step surface, and the projection of the first portion being located in the first groove segment when viewed in the first direction.

[0040] In one or more optional embodiments of the above, the second accommodating groove is a stepped groove, the second insulating piece is accommodated in the second groove segment, and the projection of the first portion is located in the first groove segment when viewed in the first direction, so that the sizes of the first groove segment and the second groove segment are matched with the sizes of the first portion and the second insulating piece respectively, thereby reducing the loss of the capacity of the fourth active material layer when the second accommodating groove is formed, and thus reducing the loss of the energy density of the battery cell.

[0041] In some embodiments of the first aspect, the second insulating piece extends beyond the end of the third tab segment close to the first tab in the width direction of the first tab.

[0042] In one or more optional embodiments of the above, the second insulating piece extends beyond the end of the third tab segment close to the first tab in the width direction of the first tab, reducing the risk of short circuit caused by the contact of the first tab with the edge of the third tab segment, and improving the safety performance of the battery cell.

[0043] In some embodiments of the first aspect of the present application, the battery cell further includes a third insulating piece connected to the first tab and located between the first current collector and the third current collector, the third insulating piece covering the first welding mark.

[0044] In one or more optional embodiments of the above, the battery cell includes a third insulating piece connected to the first tab and located between the first current collector and the third current collector, the third insulating piece covers the first portion, and the third insulating piece is capable of separating the first welding mark and the third tab segment, thereby reducing the risk of the burr of the first welding mark piercing the separator and causing a short circuit.

[0045] In some embodiments of the first aspect of the present application, the first tab receiving groove includes a third groove segment and a fourth groove segment, the third groove segment is closer to the first current collector than the fourth groove segment, and the groove side surface of the third groove segment and the groove side surface of the fourth groove segment are connected by a second step surface, and the third insulating piece is at least partially received in the fourth groove segment and connected to the second step surface.

[0046] In one or more optional embodiments of the above, the third insulating piece is received in the fourth groove segment and connected to the second step surface, the groove bottom surface of the third groove segment forms a first empty foil area, the first portion is located in the third groove segment, and the third insulating piece is located in the fourth groove segment, so that the sizes of the third groove segment and the fourth groove segment are matched with the sizes of the first portion and the third insulating piece, respectively, thereby reducing the loss of the capacity of the first active material layer during the processing of the first tab receiving groove, and thereby reducing the loss of the energy density of the battery cell.

[0047] In some embodiments of the first aspect of the present application, the first portion and the first empty foil area are connected by laser welding.

[0048] In the above technical solution, laser welding has high precision, high strength, non-contact welding, high automation, small heat-affected zone, small deformation, fast welding speed, and good material adaptability, so that the connection between the first portion and the first empty foil area is more temperature-resistant, and the influence on the second active material layer is small. Compared with ultrasonic welding, ultrasonic welding needs to set a welding head and a welding seat, and the active material layer opposite the tab is removed.

[0049] In some embodiments of the first aspect of the present application, the battery cell includes a separator disposed between the first tab and the second tab, and the first insulating piece is disposed on the separator.

[0050] In the above technical solution, the first insulating piece is disposed on the separator, which can prevent the precipitation of metal ions from the positive electrode, reduce the risk of lithium precipitation in the battery cell, and improve the safety performance of the battery cell.

[0051] In some embodiments of the first aspect of the present application, the first tab adjacent to the first insulating piece is provided with a first receiving groove, and the projection of the first insulating piece is located within the projection of the first receiving groove along the first direction; or the second tab adjacent to the first insulating piece is provided with a first receiving groove, and the projection of the first insulating piece is located within the projection of the first receiving groove along the first direction; and the first receiving groove is disposed on the active material layer of the second tab facing the first insulating piece.

[0052] In the technical solution described above, the projection of the first insulating member is located within the projection of the first accommodating groove, so that the influence of the thickness of the first insulating member can be reduced.

[0053] In a second aspect, the embodiments of the present application provide a power consuming device, which comprises the battery cell provided in any of the embodiments described above.

[0054] In one or more optional embodiments described above, the battery cell provided in any of the embodiments described above has high safety, so that the power consuming device provided with the battery cell has good power consuming safety. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0056] FIG. 1 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0057] FIG. 2 is a cross-sectional view of A1 in FIG. 1;

[0058] FIG. 3 is a schematic view of the cooperation between a first tab segment and a first insulating member provided in some embodiments of the present application;

[0059] FIG. 4 is a cross-sectional view of a battery cell provided in some other embodiments of the present application;

[0060] FIG. 5 is an enlarged view of A2 in FIG. 4;

[0061] FIG. 6 is a schematic view of the cooperation between a first tab segment and a first insulating member provided in some other embodiments of the present application;

[0062] FIG. 7 is a cross-sectional view of a battery cell provided in some further embodiments of the present application;

[0063] FIG. 8 is an enlarged view of A3 in FIG. 7;

[0064] FIG. 9 is a cross-sectional view of a battery cell provided in some yet further embodiments of the present application;

[0065] FIG. 10 is an enlarged view of A4 in FIG. 9;

[0066] FIG. 11 is a schematic view of the cooperation between a first tab segment and a first tab provided in FIG. 9;

[0067] FIG. 12 is a schematic view of the cooperation between a second tab segment and a first insulating member provided in FIG. 9;

[0068] Fig. 13 is a sectional view of an electric core according to still further embodiments of the present application;

[0069] Fig. 14 is an enlarged view of A5 in Fig. 13;

[0070] Fig. 15 is a sectional view of an electric core according to yet further embodiments of the present application;

[0071] Fig. 16 is an enlarged view of A6 in Fig. 15;

[0072] Fig. 17 is a sectional view of an electric core according to still further embodiments of the present application;

[0073] Fig. 18 is an enlarged view of A7 in Fig. 17;

[0074] Fig. 19 is a structural schematic view of a third electrode tab according to some embodiments of the present application;

[0075] Fig. 20 is a sectional view of an electric core according to yet further embodiments of the present application;

[0076] Fig. 21 is an enlarged view of A8 in Fig. 20;

[0077] Fig. 22 is a sectional view of an electric core according to still further embodiments of the present application;

[0078] Fig. 23 is an enlarged view of A9 in Fig. 22;

[0079] Fig. 24 is a structural schematic view of a third electrode tab according to further embodiments of the present application;

[0080] Fig. 25 is a sectional view of an electric core according to still further embodiments of the present application;

[0081] Fig. 26 is an enlarged view of A10 in Fig. 25;

[0082] Fig. 27 is a schematic view of a third electrode tab and a second insulating member according to some embodiments of the present application;

[0083] Fig. 28 is a sectional view of an electric core according to yet further embodiments of the present application;

[0084] Fig. 29 is an enlarged view of A11 in Fig. 28;

[0085] Fig. 30 is a sectional view of an electric core according to still further embodiments of the present application;

[0086] Fig. 31 is an enlarged view of A12 in Fig. 30;

[0087] Fig. 32 is a schematic view of a first electrode tab and a third insulating member according to further embodiments of the present application;

[0088] Fig. 33 is a sectional view of an electric core according to yet further embodiments of the present application;

[0089] FIG. 34 is a magnified view of A13 in FIG. 33;

[0090] FIG. 35 is a magnified view of A13 in FIG. 33 (annotated dimensions);

[0091] FIG. 36 is a cross-sectional view of an electric cell provided by yet further embodiments of the application;

[0092] FIG. 37 is a magnified view of A14 in FIG. 36;

[0093] FIG. 38 is a magnified view of A14 in FIG. 36 (annotated dimensions);

[0094] FIG. 39 is a schematic view of the cooperation of a first tab and a third insulating member provided by further embodiments of the application;

[0095] FIG. 40 is a magnified view of A15 in FIG. 1.

[0096] FIG. 40 is a magnified view of A15 in FIG. 1. DETAILED DESCRIPTION

[0097] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0098] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0099] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0100] It should be noted that: similar reference numbers and letters represent similar 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.

[0101] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0102] In the description of the embodiments of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "mount", "connect" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0103] At present, from the development of market situation, the application of battery cells is more and more extensive. Battery cells are widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, as well as electric tools, unmanned aerial vehicles, energy storage equipment and many other fields. With the continuous expansion of the application field of battery cells, the demand for battery cells is also increasing, and the safety requirements for battery cells are also increasing.

[0104] The electric core includes two polar pieces with opposite polarities, and the polar piece includes a main body part and a tab. A side active material layer of the current collector of the main body part is provided with a first tab accommodating groove to expose a part of a surface of the current collector of the main body part, that is, the first tab accommodating groove is opened on one side of the main body part of the polar piece, and the tab is welded with the exposed surface of the current collector of the main body part in the first tab accommodating groove, so as to realize the electrical connection of the tab and the current collector of the main body part. In the welding process of the tab and the current collector of the main body part, the bonding network and the conductive network of the active material at the position corresponding to the first tab accommodating groove on the other side of the current collector of the main body part may be damaged, so that the metal ions of the positive electrode cannot return to the positive electrode or cannot be embedded into the negative electrode, thereby causing the lithium to be precipitated on the surface of the negative electrode and further causing the electric core to precipitate lithium, thereby reducing the safety of the electric core.

[0105] Based on the above considerations, in order to alleviate the problem of low safety of the electric core, the electric core provided by the embodiments of the present application includes a first polar piece, a first tab, a second polar piece and a first insulating piece. The first polar piece includes a first polar piece segment, and the first polar piece segment includes a first current collector, a first active material layer and a second active material layer. The first current collector has a first surface and a second surface oppositely arranged along a first direction. The first active material layer is arranged on the first surface, and the second active material layer is arranged on the second surface. The first surface has a first empty foil area, and the first active material layer is provided with a first tab accommodating groove exposing the first empty foil area. When viewed along the first direction, the second active material layer covers the first tab accommodating groove. The first tab is partially accommodated in the first tab accommodating groove, and the first tab has a first part overlapping the first empty foil area. The first part is welded with the first empty foil area to form a first welding mark. The second polar piece is opposite to the first polar piece in polarity. The second polar piece includes a second polar piece segment, and the second polar piece segment is arranged opposite to the first polar piece segment and faces the second surface along the first direction. The second polar piece includes a second current collector. The first insulating piece is at least partially arranged between the first current collector and the second current collector, and the first insulating piece covers the first welding mark when viewed along the first direction.

[0106] The first pole segment is only formed with the first empty foil area on the first surface, and the area corresponding to the first empty foil area on the second surface is covered by the second active material layer, so that the first tab accommodating groove can be formed on one side of the first pole segment when the first pole piece is manufactured, the processing technology of the first pole piece is simplified, the waste of active material and the capacity loss are reduced, and thus the energy density of the battery cell is improved. During the process of welding the first part and the first empty foil area to form the first welding mark, the bonding network and the conductive network of the part of the second active material layer corresponding to the first welding mark can be damaged, so that the metal ions of the positive electrode cannot return to the positive electrode or cannot be embedded into the negative electrode, thereby causing the lithium to be precipitated on the surface of the negative electrode and further causing the battery cell to precipitate lithium. The first insulating member is at least partially arranged between the first current collector and the second current collector, and the first insulating member covers the first welding mark when viewed in the first direction. The first insulating member can insulate and separate the area of the second active material layer corresponding to the first welding mark and the second pole segment, so as to prevent the metal ions from being precipitated on the surface of the negative electrode, reduce the risk of lithium precipitation of the battery cell, and improve the safety performance of the battery cell.

[0107] The battery cell disclosed in the embodiments of the present application can be used in, but is not limited to, electric two-wheeled vehicles, power tools, unmanned aerial vehicles, energy storage devices and other electric devices. The battery cell disclosed in the embodiments of the present application can also be used as a power supply system of an electric device, so as to improve the safety performance of the battery cell.

[0108] The embodiments of the present application provide a power consumption device using the battery cell 100 as a power supply. The power consumption device can be, but is not limited to, an electronic device, a power tool, an electric vehicle, an unmanned aerial vehicle and an energy storage device. The electronic device can include a mobile phone, a tablet computer, a notebook computer and the like. The power tool can include a power drill, a power saw and the like. The electric vehicle can include an electric car, an electric motorcycle, an electric bicycle and the like.

[0109] As shown in FIG. 1, the battery cell 100 includes a housing 10 and an electrode assembly 20, and the electrode assembly 20 is accommodated in the housing 10.

[0110] The housing 10 forms an accommodation space. The accommodation space can be used to accommodate the electrode assembly 20, an electrolyte and the like. The housing 10 can be a hard shell, such as a steel shell or an aluminum shell, to form a steel shell battery cell or an aluminum shell battery cell. The housing 10 can also be formed of a relatively soft material, such as an aluminum plastic film or a steel plastic film, to form a soft package battery cell.

[0111] The electrode assembly 20 includes a first pole piece 23, a second pole piece 24 and a separator 25. The first pole and the second pole piece 24 are opposite in polarity, that is, one of the first pole piece 23 and the second pole piece 24 is a positive pole piece 21, and the other of the first pole piece 23 and the second pole piece 24 is a negative pole piece 22. In FIG. 1, the first pole piece 23 is shown as the positive pole piece 21, and the second pole piece 24 is shown as the negative pole piece 22.

[0112] The positive electrode tab 21 includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode current collector is provided with the positive electrode active material layer on at least one side. For a lithium ion battery, the material of the positive electrode current collector can be aluminum. The positive electrode active material layer can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate, etc. The positive electrode current collector can be a composite current collector or a non-composite current collector.

[0113] The negative electrode tab 22 includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode current collector is provided with the negative electrode active material layer on at least one side. For a lithium ion battery, the material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. The negative electrode current collector can be a composite current collector or a non-composite current collector.

[0114] The isolation film 25 insulates and separates the first electrode tab 23 and the second electrode tab 24, reducing the risk of short circuit of the battery 100. The material of the isolation film 25 can include PP (polypropylene) or PE (polyethylene), etc.

[0115] The electrode assembly 20 can be a laminated structure or a wound structure.

[0116] In the embodiment in which the electrode assembly 20 is a laminated structure, the first electrode tab 23, the isolation film 25 and the second electrode tab 24 are stacked in a certain order for one or more times.

[0117] In the embodiment in which the electrode assembly 20 is a wound structure, the first electrode tab 23, the isolation film 25 and the second electrode tab 24 are stacked in a certain order, and then wound to form a wound structure. The wound electrode assembly 20 can be a flat wound electrode assembly or a cylindrical electrode assembly. In FIG. 1, the case in which the electrode assembly 20 is a flat wound electrode assembly is shown.

[0118] The first electrode tab 23 includes a first electrode tab segment 231, and the first electrode tab segment 231 includes a first current collector 2311, a first active material layer 2312 and a second active material layer 2313. The first current collector 2311 has a first surface 23111 and a second surface 23112 oppositely arranged along a first direction X, the first active material layer 2312 is arranged on the first surface 23111, and the second active material layer 2313 is arranged on the second surface 23112.

[0119] In the embodiment in which the first electrode tab 23 is a positive electrode tab 21, the first current collector 2311 is a positive electrode current collector, and the first active material layer 2312 and the second active material layer are both positive electrode active material layers. In the embodiment in which the first electrode tab 23 is a negative electrode tab 22, the first current collector 2311 is a negative electrode current collector, and the first active material layer 2312 and the second active material layer 2313 are both negative electrode active material layers.

[0120] As shown in FIG. 1 and FIG. 2, the first surface 23111 has a first empty foil area Q1, and the first active material layer 2312 is provided with a first tab accommodating groove 23121 which exposes the first empty foil area Q1. Understandably, the depth of the first tab accommodating groove 23121 is the same as the thickness of the first active material layer 2312, and the first empty foil area Q1 is the groove bottom wall of the first tab accommodating groove 23121. In the width direction Y of the first tab segment, the first tab accommodating groove 23121 extends to one edge of the first active material layer 2312, and then the first tab accommodating groove 23121 has three groove side walls.

[0121] As viewed in the first direction X, the second active material layer 2313 covers the first tab accommodating groove 23121. Understandably, the second active material layer 2313 covers the area of the second surface 23112 corresponding to the first empty foil area Q1, that is, as viewed in the thickness direction of the first tab segment 231, the projection of the first empty foil area Q1 is located in the second active material layer 2313. The first tab segment 231 is only formed with the first empty foil area Q1 on the first surface 23111, and the area of the second surface 23112 corresponding to the first empty foil area Q1 is covered by the second active material layer 2313. In this way, the first tab accommodating groove 23121 can be formed on only one side of the first tab segment 231 when manufacturing the first tab 23, which simplifies the processing process of the first tab 23, reduces the waste of active material and capacity loss, and thus helps to improve the energy density of the battery cell 100.

[0122] As shown in FIG. 1, the electrode assembly 20 includes a flat area 20a and two bending areas 20b connected to the two ends of the flat area 20a. The first tab segment 231 can be a section of the first tab 23 located in the flat area 20a.

[0123] As shown in FIG. 2 and FIG. 3, the first tab 30 is partially accommodated in the first tab accommodating groove 23121, and the first tab 30 has a first part 31 overlapping the first empty foil area Q1. The first part 31 and the first empty foil area Q1 are welded to form a first welding mark Q.

[0124] The welding mark described in the present application refers to an area, that is, an area composed of multiple welding points, and does not refer to only one welding point.

[0125] In some embodiments, the first part 31 and the first empty foil area Q1 are welded by laser welding. Laser welding has high precision, high strength, non-contact welding, high automation, small heat-affected zone, small deformation, fast welding speed, good material adaptability, so that the connection between the first part and the first empty foil area is more temperature, and has less effect on the second active material layer.

[0126] In other embodiments, the first portion 31 and the first empty foil region Q1 can also be welded by ultrasonic welding.

[0127] Another portion of the first tab 30 extends out of the first tab receiving groove 23121 along the width direction Y of the first tab segment. The thickness of the first tab 30 can be less than the depth of the first tab receiving groove 23121. The thickness of the first tab 30 can also be greater than or equal to the depth of the first tab receiving groove 23121.

[0128] In some embodiments, along the length direction Z of the first tab segment, the size of the first empty foil region Q1 is W'7 and the size of the first portion 31 is W3, and along the width direction Y of the first tab segment, the size of the first empty foil region Q1 is L'7 and the size of the first portion 31 is L3, wherein 0.1mm≤W'7-W3≤3mm, 0.1mm≤L'7-L3≤3mm.

[0129] Exemplarily, W'7-W3 can be 0.1mm, 0.5mm, 0.7mm, 1mm, 1.3mm, 1.5mm, 1.7mm, 2mm, 2.3mm, 2.5mm, 2.7mm, 3mm, etc.

[0130] L'7-L3 can be 0.1mm, 0.5mm, 0.7mm, 1mm, 1.3mm, 1.5mm, 1.7mm, 2mm, 2.3mm, 2.5mm, 2.7mm, 3mm, etc.

[0131] W'7-W3≥0.1mm, L'7-L3≥0.1mm, which facilitates the first portion 31 to be accommodated in the first tab receiving groove 23121, and also reserves space for the connection between the first portion 31 and the first empty foil region Q1, reduces the risk of the welding energy of the first portion 31 and the first empty foil region Q1 damaging the first active material layer 2312 during welding, thereby reducing the lithium precipitation of the battery cell 100, improving the safety of the battery cell 100, and also reducing the capacity loss of the battery cell 100, which is conducive to the battery cell 100 having a higher energy density. W'7-W3≤3mm, L'7-L3≤3mm, which avoids the area of the first empty foil region Q1 not overlapping with the first tab 30 being too large to cause space waste and increase the risk of short circuit of the battery cell 100, which is conducive to the battery cell 100 having a higher energy density and safety performance.

[0132] It should be noted that W'7 can be the size of the first empty foil region Q1 in the length direction Z of the first tab segment, and L'7 can be the size of the first empty foil region Q1 in the width direction Y of the first tab segment; W3 can be the size of the first portion 31 in the length direction Z of the first tab segment, and L3 can be the size of the first portion 31 in the width direction Y of the first tab segment.

[0133] The size of the first portion 31 and the size of the first weld Q can be the same or different along the length direction Z of the first tab segment. The size of the first portion 31 and the size of the first weld Q can be the same or different along the width direction Y of the first tab segment. In FIGS. 2 and 3, the size of the first portion 31 is greater than the size of the first weld Q along the length direction Z of the first tab segment, and the size of the first portion 31 is greater than the size of the first weld Q along the width direction Y of the first tab segment.

[0134] The second tab 24 includes a second tab segment 241 disposed opposite the first tab segment 231 and facing the second surface 23112 along the first direction X. The second tab segment 241 can be a segment of the second tab 24 located in the flat area 20a. The first direction X, the thickness direction of the first tab segment 231, and the thickness direction of the second tab segment 241 are parallel.

[0135] The second tab segment 241 includes a second current collector 2411 and a third active material layer 2412 disposed on a surface of the second current collector 2411 facing the first tab segment 231. In an embodiment in which the second tab 24 is a positive electrode tab, the second current collector 2411 is a positive electrode current collector, and the third active material layer 2412 is a positive electrode active material layer. In an embodiment in which the second tab 24 is a negative electrode tab, the second current collector 2411 is a negative electrode current collector, and the third active material layer 2412 is a negative electrode active material layer.

[0136] As shown in FIG. 2, the battery cell 100 further includes a first insulating member 40 disposed at least partially between the first current collector 2311 and the second current collector 2411, covering the first portion 31 as viewed along the first direction X.

[0137] The first insulating member 40 can be located completely between the first current collector 2311 and the second current collector 2411. The first insulating member 40 can be located partially between the first current collector 2311 and the second current collector 2411, and another portion of the first insulating member 40 extends out of the first current collector 2311 and the second current collector 2411 along the width direction Y of the first tab segment and / or the length direction Z of the first tab segment.

[0138] The first insulating member 40 covers the first weld Q completely as viewed along the first direction X.

[0139] The first insulating member 40 can be disposed on the first tab segment 231, on the second tab segment 241, or on the separation film 25 between the first tab segment 231 and the second tab segment 241.

[0140] In the process of welding the first portion 31 and the first empty foil area Q1 to form the first welding spot Q, the bonding network and the conductive network of the second active material layer 2313 corresponding to the first welding spot Q can be damaged, so that the metal ions of the positive electrode cannot return to the positive electrode or cannot be embedded in the negative electrode, thereby causing the lithium to be precipitated on the surface of the negative electrode and further causing the lithium precipitation of the battery cell 100. The first insulating member 40 is at least partially arranged between the first current collector 2311 and the second current collector 2411, and the first insulating member 40 covers the first welding spot Q in the first direction X. The first insulating member 40 can insulate and separate the area of the second active material layer 2313 corresponding to the first welding spot Q and the second tab segment 241, so as to prevent the metal ions from being precipitated on the surface of the negative electrode, reduce the risk of lithium precipitation of the battery cell 100, and improve the safety performance of the battery cell 100.

[0141] In some embodiments, along the length direction Z of the first tab segment, the size of the first insulating member 40 is W1, the size of the first welding spot Q is W'3, and the size of the first tab receiving groove 23121 is K, and W'3

[0142] Along the width direction Y of the first tab segment, the size of the first insulating member 40 is L1, the size of the first welding spot Q is L'3, and the size of the first tab receiving groove 23121 is G, and L'3

[0143] W1 can be the size of the first insulating member 40 along the length direction Z of the first tab segment, and L1 can be the size of the first insulating member 40 along the width direction Y of the first tab segment.

[0144] In one or more optional embodiments above, due to the welding of the first portion and the first empty foil area, the heat generated by the welding can easily cause the deactivation of the active material on the back surface opposite to the welding spot, leading to lithium precipitation phenomenon, and therefore the size of the first insulating member is required to be W'3 1， If the size of the first insulating member is equal to the size of the first tab receiving groove, the active material that is not deactivated by welding will be covered, resulting in a loss of energy density, and when the size of the first insulating member is greater than the size of the first tab receiving groove, the excess part of the adhesive paper will cause the thickness of the tab to be relatively thick, and when the size of the first insulating member is smaller than the size of the first tab receiving groove, the thickness of the first insulating member will be partially balanced with the depth of the first tab receiving groove, so that W1

[0145] L'2 < L1, so that the first insulating piece 40 can completely cover the second active material layer 2313 corresponding to the region of the first welding mark Q when viewed in the first direction X, thereby reducing the risk of metal ions that cannot return to the positive electrode or cannot be embedded in the negative electrode of the region corresponding to the first welding mark Q of the positive electrode being precipitated on the surface of the negative electrode, thereby improving the safety performance of the battery cell 100. W1 < K and L1 < G, so that the first insulating piece 40 can be embedded in the first tab accommodating groove 23121, reducing the impact of the first insulating piece 40 on the energy density of the battery cell 100 and reducing the size difference between the parts of the battery cell 100, thereby alleviating the uneven stress on the pole piece, the deterioration of the contact interface, and the black spots and even lithium precipitation on the interface after the cycle. The problems can also be alleviated, and the battery cell 100 has a higher energy density, and the safety performance of the battery cell 100 can also be improved.

[0146] In some embodiments, the size of the first part in the length direction Z of the first pole piece segment is W3, and the size of the first part in the width direction Y of the first pole piece segment is L3, W3 < W1, and L3 < L1.

[0147] W3 < W1 and L3 < L1, so that the first insulating piece can completely cover the second active material layer 2313 corresponding to the region of the first part 31 when viewed in the first direction, further reducing the risk of metal ions that cannot return to the positive electrode or cannot be embedded in the negative electrode being precipitated on the surface of the negative electrode when the first welding mark Q is formed, thereby improving the safety performance of the battery cell 100.

[0148] In some embodiments, one of the first pole piece 23 and the second pole piece 24 is the positive electrode pole piece 21, and the first insulating piece 40 is arranged on the positive electrode pole piece 21.

[0149] The first insulating piece 40 can be bonded to the positive electrode pole piece 21. For example, the first insulating piece 40 is a glue paper, and the glue paper is bonded to the positive electrode pole piece 21.

[0150] The first insulating piece 40 is arranged on the positive electrode pole piece 21, which can prevent metal ions in the region of the positive electrode pole piece 21 corresponding to the first welding mark Q from being precipitated from the positive electrode pole piece 21, which can better reduce the risk of lithium precipitation of the battery cell 100, thereby improving the safety performance of the battery cell 100.

[0151] As shown in FIG. 2 and FIG. 3, in some embodiments, the first tab 23 is the positive electrode tab 21, and the first insulating piece 40 can be arranged on the surface of the second active material layer 2313 facing away from the first current collector 2311. The first insulating piece 40 arranged on the surface of the second active material layer 2313 facing away from the first current collector 2311 can prevent metal ions in the area of the second active material layer 2313 corresponding to the first empty foil area Q1 from being precipitated from the positive electrode tab 21, thereby better reducing the risk of lithium precipitation of the battery cell 100 and improving the safety performance of the battery cell 100.

[0152] In other embodiments, as shown in FIG. 4 and FIG. 5, the surface of the second active material layer 2313 facing the second tab segment 241 is provided with a first accommodating groove 50, and the first insulating piece 40 is at least partially arranged in the first accommodating groove 50.

[0153] The first accommodating groove 50 can extend to one end of the second active material layer 2313 close to the first tab 30 along the width direction Y of the first tab segment. In some embodiments, along the width direction Y of the first tab segment, a part of the first insulating piece 40 is accommodated in the first accommodating groove 50, and another part of the first insulating piece 40 extends out of the first accommodating groove 50 along the width direction Y of the first tab segment, so that a part of the first insulating piece 40 is accommodated in the first accommodating groove 50.

[0154] In some embodiments, the depth of the first accommodating groove can be less than the thickness of the first insulating piece 40, so that the first insulating piece 40 protrudes out of the first accommodating groove 50 in the first direction X, so that a part of the first insulating piece 40 is accommodated in the first accommodating groove 50. The depth of the first accommodating groove 50 is the size of the first accommodating groove 50 recessed from the surface of the second active material layer 2313 facing away from the first current collector 2311 to the direction close to the first current collector 2311.

[0155] Of course, in the embodiments in which the first tab 23 is the positive electrode tab, the first insulating piece 40 can be completely accommodated in the first accommodating groove 50.

[0156] By arranging the first accommodating groove 50 on the second active material layer 2313 and at least partially arranging the first insulating piece 40 in the first accommodating groove 50, not only is the arrangement of the first insulating piece 40 facilitated, but also the first insulating piece 40 and the first tab segment 231 overlap in space, which can reduce the size of the battery cell 100 in the thickness direction of the first insulating piece 40, reduce the impact of the arrangement of the first insulating piece 40 on the energy density of the battery cell 100, and reduce the size difference between the parts of the battery cell 100, thereby alleviating the uneven stress on the tab, the deterioration of the contact interface, and the black spots and lithium precipitation on the interface after cycling, thereby improving the energy density of the battery cell 100 and improving the safety performance of the battery cell 100.

[0157] In some embodiments, the depth of the first accommodation groove 50 can be less than the thickness of the second active material layer 2313. The thickness of the second active material layer 2313 is the dimension of the second active material layer 2313 in the first direction X. As shown in FIG. 4 and FIG. 5, the depth T1 of the first accommodation groove 50, and the thickness H2 of the second active material layer 2313, T1 < H2.

[0158] The depth of the first accommodation groove 50 being less than the thickness of the second active material layer 2313 can reduce the loss of active material when the first accommodation groove 50 is formed on the second active material layer 2313.

[0159] In other embodiments, the depth of the first accommodation groove 50 can be the same as the thickness of the second active material layer 2313, which facilitates the processing of the first accommodation groove 50.

[0160] As shown in FIG. 4-FIG. 6, in embodiments where the first tab 23 is a positive electrode tab 21, along the length direction Z of the first tab segment, the size of the first insulating member 40 is W1, and the size of the first accommodation groove 50 is W2, along the width direction Y of the first tab segment, the size of the first insulating member 40 is L1, and the size of the first accommodation groove 50 is L2, 0.1mm≤W2-W1≤2mm, 0.1mm≤L2-L1≤2mm.

[0161] After the first insulating member 40 is accommodated in the first accommodation groove 50, the first insulating member 40 can have a gap with any side wall of the first accommodation groove 50, which reduces the risk of the first insulating member 40 and the second active material layer 2313 being extruded. Also, the first insulating member 40 can avoid being on the second active material layer 2313 due to the tolerance in production.

[0162] Exemplarily, W2-W1 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0163] L2-L1 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0164] W2-W1≥0.1mm, L2-L1≥0.1mm, not only facilitates the installation of the first insulating piece 40, but also reserves space for the expansion of the first insulating piece 40 and the active material layer during the circulation of the battery cell 100, alleviates the problem of the active material layer and the first insulating piece 40 being extruded due to the expansion of the tab during the circulation of the battery cell 100, is conducive to improving the stability of the first insulating piece 40, and further improves the safety performance of the battery cell 100. W2-W1≤2mm, L2-L1≤2mm, reduces space waste, is conducive to the battery cell 100 having a high energy density, and can also reduce the area of the region of the bottom wall of the first receiving groove 50 that is not covered by the first insulating piece 40, reduce the risk of lithium precipitation, and further improve the safety performance of the battery cell 100.

[0165] As shown in FIGS. 2, 3, and 5, 6, in the embodiment in which the first tab 23 is a positive electrode tab 21, along the length direction Z of the first tab segment, the size of the first welding mark Q is W'3, and the size of the first insulating piece 40 is W1; along the width direction Y of the first tab segment, the size of the first welding mark Q is L'3, and the size of the first insulating piece 40 is L1; 0.1mm≤W1-W'3≤3mm, 0.1mm≤L1-L'3≤3mm.

[0166] As viewed along the first direction X, the first insulating piece 40 completely covers the first welding mark Q, and along the length direction Z of the first tab segment and the width direction of the first tab 23, the first insulating piece 40 can exceed the first welding mark Q or the first portion 31.

[0167] Exemplarily, W1-W'3 can be 0.1mm, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2mm, 2.3mm, 2.5mm, 2.7mm, 2.9mm, 3mm, etc.

[0168] Exemplarily, L1-L'3 can be 0.1mm, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2mm, 2.3mm, 2.5mm, 2.7mm, 2.9mm, 3mm, etc.

[0169] W1-W3≥0.1mm, L1-L'3≥0.1mm, due to the area affected by welding is slightly larger than the welding area, about 0.1mm, therefore, the width and length of the first insulating piece 40 need to be 0.1mm more than the welding mark, so that the first insulating piece 40 can completely cover the deactivated active material, and can better prevent the metal ions in the area corresponding to the first welding mark Q of the positive pole piece from being precipitated, reduce the risk of lithium precipitation of the battery cell 100, and improve the safety performance of the battery cell 100. W1-W'3≤3mm, L1-L'3≤3mm, reduce the space occupied by the first insulating piece 40, thereby reducing the capacity loss of the battery cell 100, thereby facilitating the battery cell 100 to have a higher energy density.

[0170] As shown in FIGS. 7 and 8, the second pole piece 24 is a positive pole piece 21, the second pole piece segment 241 includes a second current collector 2411 and a third active material layer 2412, the third active material layer 2412 is disposed on the surface of the second current collector 2411 facing the first pole piece segment 231, and the first insulating piece 40 is disposed on the surface of the third active material layer 2412 away from the second current collector 2411, which can prevent the metal ions in the area corresponding to the first empty foil area Q1 of the third active material layer 2412 from being precipitated from the positive pole piece 21, which can better reduce the risk of lithium precipitation of the battery cell 100, thereby improving the safety performance of the battery cell 100.

[0171] In other embodiments, as shown in FIGS. 9 and 10, the surface of the third active material layer 2412 facing the first pole piece segment 231 is provided with a first accommodating groove 50, and the first insulating piece 40 is at least partially disposed in the first accommodating groove 50.

[0172] The first accommodating groove 50 disposed on the third active material layer 2412 can extend to one end of the third active material layer 2412 close to the first pole tab 30 along the width direction Y of the first pole piece segment. In some embodiments, along the width direction Y of the first pole piece segment, a portion of the first insulating piece 40 is accommodated in the first accommodating groove 50, and another portion of the first insulating piece 40 extends out of the first accommodating groove 50 along the width direction Y of the first pole piece segment, so that a portion of the first insulating piece 40 is accommodated in the first accommodating groove 50.

[0173] In embodiments in which the second pole piece is a positive pole piece, the depth of the first accommodating groove 50 can be less than the thickness of the second insulating piece 70, so that the second insulating piece 70 protrudes out of the first accommodating groove in the first direction, so that a portion of the first insulating piece 40 is accommodated in the first accommodating groove 50. Wherein the depth of the first accommodating groove 50 is the size of the first accommodating groove 50 recessed from the surface of the third active material layer 2412 away from the second current collector 2411 to the direction close to the second current collector 2411.

[0174] Of course, in the embodiment in which the second tab 24 is a positive electrode tab, the first insulating member 40 can be completely accommodated in the first accommodation groove 50.

[0175] By providing the first accommodation groove 50 in the third active material layer 2412 and disposing the first insulating member 40 in the first accommodation groove 50, not only is the disposition of the first insulating member 40 facilitated, but also the first insulating member 40 and the second tab segment 241 spatially overlap, which can reduce the size of the battery cell 100 in the thickness direction of the first insulating member 40, reduce the impact of the disposition of the first insulating member 40 on the energy density of the battery cell 100, and reduce the size difference between parts of the battery cell 100, so as to alleviate the uneven stress on the tab, the deterioration of the contact interface, and the appearance of black spots or even lithium precipitation in the interface after cycling, thereby alleviating the problems of the tab, improving the safety performance of the battery cell 100, and enabling the battery cell 100 to have a higher energy density.

[0176] In some embodiments, the depth of the first accommodation groove 50 can be less than the thickness of the third active material layer 2412. The depth of the first accommodation groove 50 is the size of the first accommodation groove 50 recessed from the surface of the third active material layer 2412 away from the second current collector 2411 to the direction close to the second current collector 2411. The thickness of the third active material layer 2412 is the size of the third active material layer 2412 in the first direction X. As shown in FIG. 10, the depth T1 of the first accommodation groove 50 and the thickness H3 of the third active material layer 2412 satisfy T1 < H3.

[0177] The depth of the first accommodation groove 50 is less than the thickness of the third active material layer 2412, which can reduce the loss of active material when the first accommodation groove 50 is opened in the third active material layer 2412. Moreover, it prevents the metal foil from being exposed at the bottom of the first accommodation groove 50, which causes a safety risk.

[0178] In other embodiments, the depth of the first accommodation groove 50 can be the same as the thickness of the third active material layer 2412, which facilitates the processing of the first accommodation groove 50.

[0179] As shown in FIGS. 10-12, in the embodiment in which the first tab 23 is a negative electrode tab 22 and the second tab 24 is a positive electrode tab 21, along the length direction of the second tab segment 241, the size of the first insulating member 40 is W1, and the size of the first accommodation groove 50 is W2. Along the width direction of the second tab segment 241, the size of the first insulating member 40 is L1, and the size of the first accommodation groove 50 is L2. 0.1 mm ≤ W2-W1 ≤ 4 mm, and 0.1 mm ≤ L2-L1 ≤ 3 mm.

[0180] After the first insulating piece 40 is accommodated in the first accommodating groove 50 of the second tab segment 241, the first insulating piece 40 can have a gap with any side wall of the first accommodating groove 50, which reduces the risk of extrusion of the first insulating piece 40 and the third active material layer 2412. Also, the first insulating piece 40 can be prevented from being on the third active material layer 2412, thereby avoiding the thickness superposition and covering part of the active material.

[0181] Exemplarily, W2-W1 can be 0.1 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, etc.

[0182] L2-L1 can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, etc.

[0183] W2-W1≥0.1 mm and 0.1 mm≤L2-L1≥0.1 mm, which not only facilitates the installation of the first insulating piece 40, but also reserves space for the expansion of the first insulating piece 40 and the active material layer during the circulation of the battery cell 100, alleviates the problem of extrusion of the active material layer and the first insulating piece 40 caused by the expansion of the tab during the circulation of the battery cell 100, is conducive to improving the stability of the first insulating piece 40, and further improves the safety performance of the battery cell 100. W2-W1≤4 mm and L2-L1≤3 mm, which reduces the waste of space, is conducive to the battery cell 100 having a higher energy density, and also reduces the risk of lithium precipitation and further improves the safety performance of the battery cell 100.

[0184] In the embodiment in which the first tab 23 is the negative tab 22 and the second tab 24 is the positive tab 21, along the length direction Z of the first tab segment, the size of the first welding mark Q is W'3, and the size of the first insulating piece 40 is W1. Along the width direction Y of the first tab segment, the size of the first welding mark Q is L'3, and the size of the first insulating piece 40 is L1. 0.1 mm≤W1-W'3≤5 mm and 0.1 mm≤L1-L'3≤3 mm.

[0185] In the embodiment in which the first tab 23 is the negative electrode tab 22, the first insulating piece 40 completely covers the first welding mark Q as viewed in the first direction X, and in the length direction Z of the first tab segment and the width direction of the first tab 23, the first insulating piece 40 can extend beyond the first welding mark Q or the first portion 31.

[0186] Exemplarily, W1-W'3 can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2 mm, 2.3 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc.

[0187] Exemplarily, L1-L'3 can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2 mm, 2.3 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3 mm, etc.

[0188] W1-W'3≥0.1 mm, 0.1 mm≤L1-L'3≥0.1 mm, since the heat of welding will spread, the area affected by welding is slightly larger than the welding area, about 0.1 mm, so the width and length of the first insulating piece 40 need to be 0.1 mm larger than the welding mark, so that the first insulating piece 40 can completely cover the deactivated active material, better prevent the metal ions in the area corresponding to the first welding mark Q of the positive electrode tab from being precipitated, reduce the risk of lithium precipitation of the battery cell 100, and improve the safety performance of the battery cell 100. W1-W'3≤5 mm, L1-L'3≤3 mm, to reduce the space occupied by the first insulating piece 40, thereby reducing the capacity loss of the battery cell 100, thereby facilitating the battery cell 100 to have a higher energy density.

[0189] As shown in FIGS. 5 and 10, in some embodiments, the depth of the first accommodating groove 50 is greater than or equal to the thickness of the first insulating piece 40.

[0190] The thickness of the first insulating piece 40 is the dimension of the first insulating piece 40 in the first direction X.

[0191] The depth of the first accommodating groove 50 is greater than or equal to the thickness of the first insulating piece 40, so that the first insulating piece 40 can be completely accommodated in the first accommodating groove 50 in the thickness direction of the first insulating piece 40, avoiding the first insulating piece 40 extending out of the first accommodating groove 50 in the thickness direction thereof, thereby avoiding the increase in the size of the battery cell 100 in the thickness direction of the first insulating piece 40 due to the arrangement of the first insulating piece 40, thereby reducing the loss of energy density of the battery cell 100 due to the arrangement of the first insulating piece 40, so that the battery cell 100 has a better energy density.

[0192] In the embodiment in which the depth of the first accommodating groove 50 is greater than the thickness of the first insulating piece 40, the depth of the first accommodating groove 50 is T1, the thickness of the first insulating piece 40 is C1, and 0.1 μm≤T1-C1≤10 μm.

[0193] Exemplarily, T1-C1 can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.

[0194] T1-C1≥0.1 μm, the first insulating piece 40 will not protrude from the surface of the active material layer away from the current collector, avoiding the first insulating piece 40 increasing the size of the battery cell 100 in the thickness direction of the first insulating piece 40, reducing the influence of the setting of the first insulating piece 40 on the energy density of the battery cell 100 and reducing the size difference of each part of the battery cell 100, so as to alleviate the surface unevenness of the battery cell 100 caused by the setting of the first insulating piece 40, thereby alleviating the problems of uneven stress on the pole piece, poor contact interface and black spots on the interface after cycling, even lithium precipitation, and also making the battery cell 100 have a higher energy density, and also improving the safety performance of the battery cell 100. In addition, it is also convenient for the installation of the first insulating piece 40, and also reserves space for the expansion of the first insulating piece 40 and the active material layer during the cycling process of the battery cell 100, alleviating the problem of extrusion of the active material layer and the first insulating piece 40 caused by the expansion of the pole piece during the cycling process of the battery cell 100, which is conducive to improving the stability of the first insulating piece 40 and further improving the safety performance of the battery cell 100. T1-C1≤10 μm, reducing space waste, which is conducive to the battery cell 100 having a higher energy density.

[0195] The first accommodating groove 50 can have various structures, and in FIGS. 5 and 10, the first accommodating groove 50 is a rectangular groove.

[0196] The first accommodating groove 50 can also be a stepped groove. For example, as shown in FIGS. 13 and 14, the first accommodating groove 50 includes a first sub-groove section 51 and a second sub-groove section 52, the second sub-groove section 52 is closer to the first current collector 2311 than the first sub-groove section 51, the groove side surface of the first sub-groove section 51 and the groove side surface of the second sub-groove section 52 are connected by a connecting step surface 53, and the first insulating piece 40 is accommodated in the second sub-groove section 52 and connected to the connecting step surface 53 along the first direction X. The depth of the first sub-groove section 51 can be greater than or equal to the thickness of the first insulating piece 40, so that the first insulating piece 40 does not protrude out of the first sub-groove section 51 along the thickness direction of the first insulating piece 40. By setting the first accommodating groove 50 as a stepped groove, part of the active material can be left at the bottom of the first accommodating groove 50, and the safety problem caused by the exposure of the metal foil can be avoided.

[0197] In the embodiment in which the first accommodating groove 50 is a stepped groove, the size of the first sub-groove section 51 along the length direction of the first pole piece 23 is W 21 , the size of the first sub-groove section 51 along the width direction of the first pole piece 23 is L 21 , 0.1mm≤W 21 -W1≤4mm, 0.1mm≤L 21 -L1≤3mm.

[0198] After the first insulating piece 40 is accommodated in the first sub-groove section 51, a gap can exist between the first insulating piece 40 and any groove side wall of the first sub-groove section 51, which reduces the risk of extrusion between the first insulating piece 40 and the third active material layer 2412. In addition, the first insulating piece 40 can not reach the third active material layer 2412, thereby avoiding the thickness superposition and covering part of the active material.

[0199] For example, W 21 -W1 can be 0.1mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, etc.

[0200] L 21 -L1 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm, 3mm, etc.

[0201] W 21W1≥0.1mm, L 21 L1≥0.1mm, not only facilitates the installation of the first insulating piece 40, but also reserves space for the expansion of the first insulating piece 40 and the active material layer during the circulation of the battery cell 100, alleviates the problem of the active material layer and the first insulating piece 40 being extruded due to the expansion of the tab during the circulation of the battery cell 100, is conducive to improving the stability of the first insulating piece 40, and further improves the safety performance of the battery cell 100. 21 W1≤4mm, L 21 L1≤3mm, reduces space waste, is conducive to the battery cell 100 having a high energy density, and also enables the area of the region of the bottom wall of the first accommodating groove 50 that is not covered by the first insulating piece 40 to reduce the risk of lithium precipitation, further improving the safety performance of the battery cell 100.

[0202] As shown in FIGS. 15-19, in some embodiments, the second tab 24 further includes a third tab segment 242, the first tab segment 231 being located between the second tab segment 241 and the third tab segment 242; the third tab segment 242 includes a third current collector 2421 and a fourth active material layer 2422, the fourth active material layer 2422 being disposed on the surface of the third current collector 2421 facing the first tab segment 231, the surface of the fourth active material layer 2422 facing the first tab segment 231 being provided with a second accommodating groove 60, and the projection of the first part 31 and the projection of the first insulating piece 40 both being located within the second accommodating groove 60 when viewed along the first direction X.

[0203] As shown in FIGS. 16, 19 or FIGS. 18, 19, the second accommodating groove 60 is recessed from the surface of the fourth active material layer 2422 away from the third current collector 2421 to the third current collector 2421, i.e., the depth of the second accommodating groove 60 is the same as the thickness of the fourth active material layer 2422. The second accommodating groove 60 is provided on the fourth active material layer 2422 to expose the surface of the third current collector 2421 facing the first tab segment 231 to form a second empty foil area Q2.

[0204] In other embodiments, the depth of the second accommodating groove 60 can also be less than the thickness of the fourth active material layer 2422.

[0205] By providing the second accommodating groove 60 on the fourth active material layer 2422, the projection of the first part 31 and the projection of the first insulating piece 40 are both located within the second accommodating groove 60 when viewed along the first direction X, which can reduce the size of the battery cell 100 in the thickness direction of the first insulating piece 40, reduce the impact of the setting of the first insulating piece 40 on the energy density of the battery cell 100, and reduce the size difference between the parts of the battery cell 100, so as to alleviate the uneven surface of the battery cell 100 caused by the setting of the first insulating piece 40, thereby alleviating the problems of uneven stress on the tab, poor contact interface, and black spots or even lithium precipitation on the interface after circulation, and thus improving the safety performance of the battery cell 100.

[0206] The first pole segment 231 is disposed between the second pole segment 241 and the third pole segment 242 along the first direction X.

[0207] The projection of the first portion 31 and the projection of the first insulating piece 40 are both located within the second accommodating groove 60 when viewed along the first direction X, and the size of the first portion 31 is less than or equal to the size of the second accommodating groove 60 along the length direction Z of the first pole segment, and the size of the first insulating piece 40 is less than or equal to the size of the second accommodating groove 60 along the length direction Z of the first pole segment; the size of the first portion 31 is less than or equal to the size of the second accommodating groove 60 along the width direction Y of the first pole segment, and the size of the first insulating piece 40 is less than or equal to the size of the second accommodating groove 60 along the width direction Y of the first pole segment.

[0208] As shown in FIGS. 16, 18, and 19, the second accommodating groove 60 can be a rectangular groove.

[0209] In other embodiments, the second accommodating groove 60 can be a stepped groove. As shown in FIGS. 20-24, the second accommodating groove 60 includes a first groove segment 61 and a second groove segment 62, and the groove side surface of the first groove segment 61 and the groove side surface of the second groove segment 62 are connected by a first step surface 63. The first groove segment 61 is closer to the third current collector 2421 than the second groove segment 62 along the first direction X. The second insulating piece 70 is at least partially accommodated in the second groove segment 62 and connected to the first step surface 63. In embodiments in which the second accommodating groove 60 exposes the surface of the third current collector 2421 facing the first pole segment 231 to form the second empty foil area Q2, the first groove segment 61 is recessed to the third current collector 2421 to expose the third current collector 2421 to form the second empty foil area Q2. The projection of the first weld Q and the projection of the first portion 31 are both located within the first groove segment 61 when viewed along the first direction.

[0210] The second accommodating groove 60 is a stepped groove, and the second insulating piece 70 is accommodated in the second groove segment 62. The projection of the first portion 31 is located within the first groove segment 61 when viewed along the first direction X, so that the sizes of the first groove segment 61 and the second groove segment 62 match the sizes of the first portion 31 and the second insulating piece 70, respectively, thereby reducing the loss of the fourth active material layer 2422 in the process of forming the second accommodating groove 60, and reducing the loss of the energy density of the battery cell 100.

[0211] In embodiments in which the second accommodating groove 60 is a rectangular groove and the first pole segment 23 is a positive pole segment 21, the size of the first insulating piece 40 along the length direction Z of the first pole segment is W1, and the size of the second accommodating groove 60 along the length direction Z of the first pole segment is W4, and the size of the first insulating piece 40 along the width direction Y of the first pole segment is L1, and the size of the second accommodating groove 60 along the width direction Y of the first pole segment is L4, 0.1 mm≤W4-W1≤6 mm, and 0.1 mm≤L4-L1≤5 mm.

[0212] In the embodiment in which the second accommodating groove 60 is a rectangular groove and the second accommodating groove 60 exposes the third current collector 2421 to form the second empty foil area Q2, along the length direction Z of the first tab segment, the size of the second empty foil area Q2 is W'4, and along the width direction of the first tab 23, the size of the second empty foil area Q2 is L'4. Along the length direction Z of the first tab segment, the size of the second accommodating groove 60 is the same as that of the second empty foil area Q2, that is, W4=W'4. Along the width direction Y of the first tab segment, the size of the second accommodating groove 60 is the same as that of the second empty foil area Q2, that is, L4=L'4.

[0213] Exemplarily, W4-W1 can be 0.1 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0214] L4-L1 can be 0.1 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc.

[0215] W4-W1≥0.1 mm and L4-L1≥0.1 mm, not only can the first insulating member 40 be completely embedded in the second accommodating groove 60 in the length direction Z of the first tab segment and the width direction Y of the first tab segment, but also can reserve space for the expansion of the first insulating member 40 and the active material layer in the cycle process of the battery cell 100, alleviate the problem that the active material layer and the first insulating member 40 are extruded due to the expansion of the tab in the cycle process of the battery cell 100, and be conducive to improving the stability of the first insulating member 40 and further improving the safety performance of the battery cell 100. W4-W1≤6 mm and L4-L1≤5 mm, which can reduce the waste of space and the loss of the third active material, and be conducive to the battery cell 100 having a higher energy density.

[0216] In the embodiment in which the second accommodating groove 60 is a rectangular groove and the first tab 23 is a negative tab 22, the size of the first part 31 and the size of the first insulating member 40 can also be other relationships in the length direction Z of the first tab segment and the width direction Y of the first tab segment, such as 0.1 mm≤W4-W1≤5 mm and 0.1 mm≤L4-L1≤3 mm.

[0217] In the embodiment in which the second accommodating groove 60 is a stepped groove, along the length direction Z of the first tab segment, the size of the first groove segment 61 of the second accommodating groove 60 is W 41 , the size of the second groove segment 62 is W 42 , and the size of the second empty foil area Q2 is the same as that of the first groove segment 61 of the second accommodating groove 60, that is, W'4=W 41; along the width direction Y of the first tab segment, the size of the first slot segment 61 of the second receiving slot 60 is L 41 , the size of the second slot segment 62 is L 42 , the size of the second empty foil area Q2 is the same as the size of the first slot segment 61 of the second receiving slot 60, i.e. L'4 = L 41 . By setting the second receiving slot 60 as a stepped slot, part of the active material can be left at the bottom of the second receiving slot 60, avoiding the safety problem caused by the exposure of the metal foil.

[0218] In the embodiment in which the first tab 23 is the positive electrode tab 21 and the second receiving slot 60 is a stepped slot, 0.1mm≤W 41 -W3≤5mm, 0.1mm≤L 41 -L3≤3mm, that is, 0.1mm≤W'4-W3≤5mm, 0.1mm≤L'4-L3≤3mm, so that the projection of the first part 31 can be completely located in the first slot segment 61.

[0219] In the embodiment in which the first tab 23 is the negative electrode tab 22 and the second receiving slot 60 is a rectangular slot, 0.1mm≤W4-W3≤4mm, 0.1mm≤L4-L3≤3mm, that is, 0.1mm≤W'4-W3≤4mm, 0.1mm≤L'4-L3≤3mm, so that the projection of the first part 31 can be completely located in the second receiving slot 60.

[0220] As shown in FIGS. 15-24, in some embodiments, the battery cell 100 further comprises a second insulating piece 70, which is accommodated in the second receiving slot 60 and covers the first welding mark Q when viewed along the first direction X.

[0221] The second insulating piece 70 can completely cover the first welding mark Q when viewed along the first direction X.

[0222] The second insulating piece 70 can be completely accommodated in the second receiving slot 60. The second insulating piece 70 can also be partially accommodated in the second receiving slot 60.

[0223] The electric core 100 comprises a second insulating piece 70 arranged in the second accommodating groove 60 of the third tab segment 242. The second insulating piece 70 can separate the first part 31 and the third tab segment 242, and reduce the risk of the burr of the first welding mark Q piercing the isolation film 25 to cause short circuit. In the embodiment in which the second tab 24 is the positive tab 21, the second insulating piece 70 can also prevent the metal ions in the positive tab 21 from being precipitated at the position corresponding to the first empty foil area Q1, reduce the risk of lithium precipitation of the electric core 100, and improve the safety performance of the electric core 100. The second insulating piece 70 is arranged in the second accommodating groove 60 of the third tab segment 242. The arrangement of the second insulating piece 70 is facilitated, and the second insulating piece 70 and the third tab segment 242 are overlapped in space. The size of the electric core 100 in the thickness direction of the second insulating piece 70 can be reduced, the influence of the second insulating piece 70 on the energy density of the electric core 100 can be reduced, and the size difference of each part of the electric core 100 can be reduced. The uneven surface of the electric core 100 caused by the arrangement of the second insulating piece 70 can be alleviated, the uneven stress on the tab, the poor contact interface, and the black spots or lithium precipitation in the interface after the cycle can be alleviated, the electric core 100 has a high energy density, and the safety performance of the electric core 100 can be improved.

[0224] The second accommodating groove 60 can be recessed from the surface of the third current collector 2421 away from the third current collector 2421 to the direction close to the third current collector 2421. The recess depth of the second accommodating groove 60 can be less than or equal to the thickness of the fourth active material layer 2422. The second accommodating groove 60 can extend to one edge of the fourth active material layer 2422 in the direction extending out of the first tab accommodating groove 23121 along the first tab 30.

[0225] As shown in FIGS. 15-19, the second accommodating groove 60 can be a rectangular groove, which facilitates the molding of the second accommodating groove 60.

[0226] In the embodiment in which the second accommodating groove 60 is a rectangular groove as shown in FIGS. 15-19, the depth of the second accommodating groove 60 can be T2, and the thickness of the second insulating piece 70 can be C2, C2≤T2, so as to avoid the second insulating piece 70 protruding from the surface of the fourth active material layer 2422 away from the third current collector 2421.

[0227] In the embodiment in which the depth of the second accommodating groove 60 is less than the thickness of the second insulating piece 70, 0.1 μm≤T2-C2≤10 μm. Exemplarily, T2-C2 can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.

[0228] T2-C2≥0.1 pm, the second insulation piece 70 will not protrude from the surface of the fourth active material layer 2422 away from the third current collector 2421, avoiding the second insulation piece 70 increasing the size of the battery cell 100 in the thickness direction of the second insulation piece 70, reducing the influence of the second insulation piece 70 on the energy density of the battery cell 100 and reducing the size difference of each part of the battery cell 100, to alleviate the surface unevenness of the battery cell 100 caused by the setting of the second insulation piece 70, thereby alleviating the problems of uneven stress on the pole piece, poor contact interface, and black spots or even lithium precipitation on the interface after cycling. It also makes the battery cell 100 have a higher energy density, and can also improve the safety performance of the battery cell 100. In addition, it also facilitates the installation of the second insulation piece 70, and also reserves space for the expansion of the second insulation piece 70 and the fourth active material layer 2422 during the cycling process of the battery cell 100, alleviating the problem of extrusion of the fourth active material layer 2422 and the second insulation piece 70 caused by the expansion of the pole piece during the cycling process of the battery cell 100. It is beneficial to improve the stability of the second insulation piece 70 and further improve the safety performance of the battery cell 100. T2-C2≤10 pm, reducing space waste, which is beneficial to the battery cell 100 having a higher energy density.

[0229] As shown in FIGS. 20-24, in embodiments where the second receiving groove 60 is a stepped groove, the second insulation piece 70 is received in the second groove segment 62 and connected to the first step face 63. The depth of the second groove segment 62 can be greater than or equal to the thickness of the second insulation piece 70. The depth of the second groove segment 62 is T2. 21 T2 21 ≤C2. In some embodiments, 0.1 pm ≤ T2 21 -C2≤10 pm. Exemplarily, T2 21 -C2may be 0.1 pm, 0.5 pm, 1 pm, 1.5 pm, 2 pm, 2.5 pm, 3 pm, 3.5 pm, 4 pm, 4.5 pm, 5 pm, 5.5 pm, 6 pm, 6.5 pm, 7 pm, 7.5 pm, 8 pm, 8.5 pm, 9 pm, 9.5 pm, 10 pm, etc.

[0230] 0.1 pm ≤ T2 21-C2, the second insulating element 70 will not protrude from the surface of the fourth active material layer 2422 away from the third current collector 2421, thus avoiding the second insulating element 70 increasing the size of the cell 100 in the thickness direction of the second insulating element 70. This reduces the impact of the second insulating element 70 on the energy density of the cell 100 and reduces the dimensional differences of various parts of the cell 100, thereby alleviating the surface unevenness of the cell 100 caused by the second insulating element 70. This alleviates the problems of uneven electrode stress, deteriorated contact interface, and black spots or even lithium plating on the interface after cycling. It also makes the cell 100 have a higher energy density and improves the safety performance of the cell 100. In addition, it facilitates the installation of the second insulating element 70 and provides space for the expansion of the second insulating element 70 and the fourth active material layer 2422 during the cycling process of the cell 100. This alleviates the problem of the fourth active material layer 2422 and the second insulating element 70 being squeezed due to the expansion of the electrode during the cycling process of the cell 100, which is conducive to improving the stability of the second insulating element 70 and further improving the safety performance of the cell 100. T 21 -C2≤10μm reduces space waste and helps the cell 100 to have a higher energy density.

[0231] Along the length direction Z of the first pole segment, the size of the second insulating member 70 is W5, and along the width direction Y of the first pole segment, the size of the second insulating member 70 is L5.

[0232] In some embodiments, 0.1mm ≤ W5-W 41 This allows the second insulating element 70 to cover the second empty foil area Q2, reducing the risk of short circuit in the cell 100 and improving the safety performance of the cell 100.

[0233] In some embodiments, W5-W 41 The size should be ≤2mm to avoid the area of ​​the second insulating element 70 that does not correspond to the second empty foil area Q2 being too large, thereby reducing the space occupied by the second insulating element 70 and improving the energy density of the cell 100.

[0234] Of course, as shown in Figures 25 and 26, in the embodiment where the second receiving groove 60 is a rectangular groove, the second insulating member 70 can cover the second receiving groove 60, and the second insulating member 70 is connected to the surface of the fourth active material layer 2422 facing away from the third current collector 2421.

[0235] In the embodiment where the first electrode 23 is the positive electrode 21 and the second electrode 24 is the negative electrode 22, the size of the second insulating member 70 is W5 along the length direction Z of the first electrode segment, and the size of the second insulating member 70 is L5 along the width direction Y of the first electrode segment, with 0.1mm≤W5-W3≤4mm and 0.1mm≤L5-L3≤3mm.

[0236] Exemplarily, W5-W3 can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, etc.

[0237] L5-L3 can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc.

[0238] 0.1 mm≤W5-W3, 0.1 mm≤L5-L3, so that along the first direction X, the second insulating piece 70 can completely cover the first part 31, and in the process of cycling of the battery cell 100, the first tab 23 and the second tab 24 expand, causing a certain misalignment between the second insulating piece 70 and the first tab 30, so that the second insulating piece 70 can also completely cover the first part 31, further reducing the risk of short circuit caused by the burr of the first part 31 piercing the isolation film 25 at the connection position of the first part 31 and the first empty foil area Q1. W5-W3≤4 mm, L5-L3≤3 mm, reducing the influence of the second insulating piece 70 on the size of the battery cell 100, so that the battery cell 100 still has a high energy density even with the second insulating piece 70.

[0239] As shown in FIG. 27, along the width direction Y of the first tab segment, the second accommodating groove 60 extends to one end of the fourth active material layer 2422 close to the first tab 30. Along the width direction Y of the first tab, the second insulating piece 70 exceeds the third tab segment 242 at one end close to the first tab 30, reducing the risk of short circuit caused by the contact of the first tab 30 with the edge of the third tab segment 242, and improving the safety performance of the battery cell 100.

[0240] As shown in FIGS. 28 and 29 and FIGS. 30 and 31, in some embodiments, the battery cell 100 further includes a third insulating piece 80, the third insulating piece 80 being connected to the first tab 23 and located between the first current collector 2311 and the third current collector 2421, and the third insulating piece 80 covering the first welding mark Q.

[0241] The third insulating piece 80 completely covers the first welding mark Q. The third insulating piece can also completely cover the first part 31.

[0242] The battery cell 100 includes the third insulating piece 80, the third insulating piece 80 being connected to the first tab 23 and located between the first current collector 2311 and the third current collector 2421, and the third insulating piece 80 covering the first welding mark Q, so that the third insulating piece 80 can separate the first welding mark Q and the third tab segment 242, reducing the risk of short circuit caused by the burr of the first welding mark Q piercing the isolation film 25.

[0243] Along the length direction Z of the first tab segment, the size of the third insulating piece 80 is W6, and along the width direction of the first tab 23, the size of the third insulating piece 80 is L6.

[0244] As shown in FIG. 29, FIG. 32, and FIG. 31 and FIG. 32, in the embodiment in which the first tab 23 is the positive electrode tab 21 and the second receiving groove 60 is a rectangular groove, 0.1mm≤W6-W4≤9mm, 0.1mm≤L6-L4≤5mm.

[0245] Exemplarily, W6-W4may be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 8mm, 9mm, etc.

[0246] L6-L4may be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0247] Since the first tab 23 is the positive electrode tab 21, the third tab segment 242 is a part of the negative electrode tab 22, 0.1mm≤W6-W4, 0.1mm≤L6-L4, not only making the third insulating piece 80 able to completely cover the second receiving groove 60 when viewed along the first direction X, but also making the third insulating piece 80 set on the first tab segment 231 able to cover the positive electrode active material with a size exceeding the second receiving groove 60, reducing the risk of lithium precipitation of the battery cell 100 and improving the safety performance of the battery cell 100. W6-W4≤9mm, L6-L4≤5mm, reducing the space occupied by the third insulating piece 80, which is conducive to the battery cell 100 having a higher energy density.

[0248] In the embodiment in which the first tab 23 is the negative electrode tab 22 and the second receiving groove 60 is a stepped groove, along the length direction Z of the first tab segment, the size of the second groove segment 62 is W 42 , along the width direction of the first tab 23, the size of the second groove segment 62 is L 42 , 0.1mm≤W6-W 42 ≤9mm, 0.1mm≤L6-L 42 ≤5mm.

[0249] Exemplarily, W6-W 42 may be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 8mm, 9mm, etc.

[0250] L6-L 42 may be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0251] Since the first tab 23 is the positive electrode tab 21, the third tab segment 242 is a part of the negative electrode tab 22, 0.1mm≤W6-W 42 , 0.1mm≤L6-L 42 Not only can the third insulating piece 80 completely cover the second accommodating groove 60 when viewed along the first direction X, but also can cover the positive active material with a size exceeding the second accommodating groove 60 when the third insulating piece 80 is arranged at the first tab segment 231, thereby reducing the risk of lithium precipitation of the battery cell 100 and improving the safety performance of the battery cell 100. W6-W 42 ≤9mm, L6-L 42 ≤5mm, thereby reducing the space occupied by the third insulating piece 80 and facilitating the battery cell 100 to have a higher energy density.

[0252] In some embodiments, the first tab accommodating groove 23121 can be a rectangular groove.

[0253] As shown in FIGS. 28-32, in the embodiments in which the first tab accommodating groove 23121 is a rectangular groove, the third insulating piece 80 can be arranged at the surface of the first active material layer 2312 away from the first current collector 2311, facilitating the arrangement of the third insulating piece 80.

[0254] In other embodiments, the first tab accommodating groove 23121 can be a stepped groove, as shown in FIGS. 33-39, the first tab accommodating groove 23121 comprises a third groove segment 231211 and a fourth groove segment 231212, the third groove segment 231211 is closer to the first current collector 2311 than the fourth groove segment 231212, the groove side surface of the third groove segment 231211 and the groove side surface of the fourth groove segment 231212 are connected by a second step surface 231213, and the third insulating piece 80 is at least partially accommodated in the fourth groove segment 231212 and connected to the second step surface 231213.

[0255] The third insulating piece 80 is accommodated in the fourth groove segment 231212 and connected to the second step surface 231213, the groove bottom surface of the third groove segment 231211 forms a first empty foil area Q1, which corresponds to the first part 31 located in the third groove segment 231211, and the third insulating piece 80 is located in the fourth groove segment 231212, so that the sizes of the third groove segment 231211 and the fourth groove segment 231212 match the sizes of the first part 31 and the third insulating piece 80 respectively, thereby reducing the capacity loss of the first active material layer 2312 when the first tab accommodating groove 23121 is formed, and thereby reducing the energy density loss of the battery cell 100. Since the third insulating piece 80 needs to be smaller than the first tab accommodating groove 23121, and the edges of the third insulating piece 80 and the first tab accommodating groove 23121 will inevitably cause gaps, the first tab accommodating groove 23121 is made into a stepped shape, which can prevent the bottom of the first tab accommodating groove 23121 from exposing the metal foil material.

[0256] Since the groove bottom wall of the third slot segment 231211 forms the first empty foil area Q1, if the third insulating piece 80 covers the third slot segment 231211, that is, the third insulating piece 80 covers the first empty foil area Q1.

[0257] In the length direction Z of the first pole piece segment, the size of the third slot segment 231211 is W 71 , and the size of the fourth slot segment 231212 is W 72 In the width direction Y of the first pole piece segment, the size of the third slot segment 231211 is L 71 , and the size of the fourth slot segment 231212 is L 72 .

[0258] In some embodiments, 0.1mm≤W 72 -W6≤3mm, 0.1mm≤L 72 -L6≤3mm.

[0259] Exemplarily, W 72 -W6 can be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.

[0260] L 72 -L6 can be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.

[0261] 0.1mm≤W 72 -W6, 0.1mm≤L 72 -L6, in the length direction of the first pole piece 23 and the width direction of the first pole piece 23, the third insulating piece 80 can be accommodated in the fourth slot segment 231212, which can reduce the size of the battery cell 100 in the thickness direction of the third insulating piece 80, reduce the influence of the setting of the third insulating piece 80 on the energy density of the battery cell 100, and reduce the size difference of each part of the battery cell 100, so as to alleviate the uneven stress on the pole piece, the poor contact interface, and the black spots and even lithium precipitation on the interface after the cycle, thereby improving the safety performance of the battery cell 100. W 72 -W6≤3mm, L 72 -L6≤3mm, which reduces the space waste and the loss of the first active material, and is conducive to the battery cell 100 having a higher energy density.

[0262] In the embodiment in which the tab slot is a stepped slot and the first pole piece 23 is a negative pole piece 22, 0.1mm≤W5-W 72 ≤10mm, 0.1mm≤L5-L 72 ≤5mm.

[0263] Exemplarily, W5-W 72 may be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0264] L5-L 72 may be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc.

[0265] 0.1mm≤W5-W 72 , 0.1mm≤L5-L 72 so that when viewed along the first direction X, the area of the second insulating piece 70 covering the positive electrode tab 21 (the third tab segment 242) exceeds the projected area of the first tab receiving groove 23121 in the first direction X, reducing the risk of lithium precipitation of the battery cell 100 due to the negative electrode tab 22 being provided with the first tab receiving groove 23121. 72 ≤10mm, L5-L 72 ≤5mm, reducing the space occupied by the second insulating piece 70 inside the battery cell 100, which is conducive to the battery cell 100 having a higher energy density.

[0266] In embodiments where the tab groove is a rectangular groove and the first tab 23 is a negative electrode tab 22, along the length direction Z of the first tab segment, the size of the first tab receiving groove 23121 is W7, and along the width direction Y of the first tab segment, the size of the first tab receiving groove 23121 is L7, 0.1mm≤W5-W7≤10mm, 0.1mm≤L5-L7≤5mm.

[0267] Exemplarily, W5-W7may be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0268] L5-L7may be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc.

[0269] 0.1mm≤W5-W7, 0.1mm≤L5-L7, so that when viewed along the first direction X, the area of the second insulating piece 70 covering the positive electrode tab 21 (the third tab segment 242) exceeds the projected area of the first tab receiving groove 23121 in the first direction X, reducing the risk of lithium precipitation of the battery cell 100 due to the negative electrode tab 22 being provided with the first tab receiving groove 23121. W5-W7≤10mm, L5-L7≤5mm, reducing the space occupied by the second insulating piece 70 inside the battery cell 100, which is conducive to the battery cell 100 having a higher energy density.

[0270] In the embodiment in which the first tab accommodating groove 23121 is a stepped groove and the first tab 23 is a negative tab, 0.1 mm ≤ W6-W 71 ≤ 3 mm, and 0.1 mm ≤ L6-L 71 ≤ 3 mm, so that the third insulating member 80 can completely cover the first empty foil area Q1.

[0271] In the embodiment in which the first tab accommodating groove 23121 is a stepped groove, the depth of the fourth groove segment 231212 is T3, the thickness of the third insulating member 80 is C3, and 0.1 μm ≤ T3-C3 ≤ 10 μm.

[0272] Exemplarily, T3-C3 can be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.

[0273] 0.1 μm ≤ T3-C3, so the third insulating member 80 will not protrude from the surface of the first active material layer 2312 away from the first current collector 2311, avoiding that the third insulating member 80 increases the size of the battery cell 100 in the thickness direction of the third insulating member 80, reducing the influence of the setting of the third insulating member 80 on the energy density of the battery cell 100 and reducing the size difference of each part of the battery cell 100, so as to alleviate the situation that the surface of the battery cell 100 is uneven due to the setting of the third insulating member 80, thereby alleviating the problems of uneven stress on the tab, poor contact interface, and black spots or even lithium precipitation on the interface after cycling, and also making the battery cell 100 have a higher energy density and improving the safety performance of the battery cell 100. In addition, it is also convenient for the installation of the third insulating member 80, and also reserves space for the expansion of the third insulating member 80 and the first active material layer 2312 during the cycling process of the battery cell 100, alleviating the problem that the fourth active material layer 2422 and the third insulating member 80 are squeezed due to the expansion of the tab during the cycling process of the battery cell 100, which is conducive to improving the stability of the third insulating member 80 and further improving the safety performance of the battery cell 100. T3-C3 ≤ 10 μm, reducing space waste, which is conducive to the battery cell 100 having a higher energy density.

[0274] In other embodiments, the third insulating member 80 can also be arranged on the first part 31 and completely cover the welding mark Q1, or the third insulating member 80 is arranged on the first part 31 and completely covers the welding mark Q1 and the first part 31.

[0275] With reference to FIG. 1 and FIG. 40, in some embodiments, the battery cell 100 further comprises the second tab 110 and the fourth insulating piece 90, the second tab 24 comprises a fourth tab segment 243, the fourth tab segment 243 comprises a fourth current collector 2431, a fifth active material layer 2432 and a sixth active material layer 2433, the fourth current collector 2431 has a third surface 24311 and a fourth surface 24312 oppositely arranged along the first direction X, the fifth active material layer 2432 is arranged on the third surface 24311, the sixth active material layer 2433 is arranged on the fourth surface 24312, the third surface 24311 has a third empty foil area Q3, the fifth active material layer 2432 is provided with a second tab accommodating groove 24321 exposing the third empty foil area Q3, and the sixth active material layer 2433 covers the second tab accommodating groove 24321 as viewed along the first direction X; the second tab 110 is partially accommodated in the second tab accommodating groove 24321, and the second tab 110 has a second portion 1101 overlapping the third empty foil area Q3, and the second portion 1101 and the third empty foil area Q3 are welded to form a second welding mark Q'; the first tab 23 comprises a fifth tab segment 232, the fifth tab segment 232 is arranged opposite to the fourth tab segment 243 along the first direction X and faces the fourth surface 24312, and the fifth tab segment comprises a fifth current collector; and the fourth insulating piece 90 is at least partially arranged between the fourth current collector 2431 and the fifth current collector 2321, and the fourth insulating piece 90 covers the second welding mark Q' as viewed along the first direction X.

[0276] The fourth tab segment 243 is only provided with the third empty foil area Q3 on the third surface 24311, and the area corresponding to the third empty foil area Q3 on the fourth surface 24312 is covered by the sixth active material layer 2433, so that the second tab accommodating groove 24321 can be formed on one side of the fourth tab segment 243 when manufacturing the second tab 24, which simplifies the processing technology of the second tab 24, reduces the waste of active material and capacity loss, and is conducive to the energy density of the battery cell 100. Since the second portion 1101 and the third empty foil area Q3 are welded to form the second welding mark Q' during the process, the bonding network and the conductive network of the part of the sixth active material layer 2433 corresponding to the second welding mark Q' can be damaged, so that the metal ions of the positive electrode cannot return to the positive electrode or cannot be embedded in the negative electrode, thereby causing the lithium to be precipitated on the surface of the negative electrode and leading to the lithium precipitation of the battery cell 100. The fourth insulating piece 90 is at least partially arranged between the fourth current collector 2431 and the fifth current collector 2321, and the fourth insulating piece 90 covers the second welding mark Q' as viewed along the first direction X, so that the fourth insulating piece 90 can insulate and separate the area corresponding to the second welding mark Q' of the sixth active material layer 2433 and the fifth tab segment 232, so as to prevent the metal ions from being precipitated on the surface of the negative electrode, reduce the risk of lithium precipitation of the battery cell 100, and improve the safety performance of the battery cell 100.

[0277] The fourth pole segment 243 and the second pole segment 241 can be the same pole segment or different pole segments. The fifth pole segment 232 and the first pole segment 231 can be the same pole segment or different pole segments.

[0278] In some embodiments, the first insulating member 40 is provided with a first accommodating groove 50 adjacent to the first pole piece 23, and a projection of the first insulating member 40 is located within a projection of the first accommodating groove 50 along the first direction X. The first accommodating groove 50 is arranged on the second active material layer 2313 of the first pole piece 23 facing the first insulating member 40. Alternatively, the first insulating member 40 is provided with a first accommodating groove 50 adjacent to the second pole piece 24, and a projection of the first insulating member 40 is located within a projection of the first accommodating groove 50 along the first direction X. The first accommodating groove is arranged on the active material layer of the second pole piece 24 facing the first insulating member 40.

[0279] The projection of the first insulating member 40 is located within the projection of the first accommodating groove 50, which can reduce the influence of the thickness of the first insulating member 40.

[0280] The application also provides a power-consuming device, which comprises the battery cell 100 provided by any of the above embodiments.

[0281] The battery cell 100 provided by any of the above embodiments has high safety, and thus the power-consuming device provided with the battery cell 100 has good power consumption safety.

[0282] The above only describes the preferred embodiments of the application and is not used to limit the application. The application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An electric cell, comprising: a first tab including a first tab segment, the first tab segment including a first current collector, a first active material layer, and a second active material layer, the first current collector having a first surface and a second surface oppositely arranged along a first direction, the first active material layer being arranged on the first surface, the second active material layer being arranged on the second surface, the first surface having a first empty foil region, the first active material layer being provided with a first tab receiving groove exposing the first empty foil region, a region of the second surface opposite to the first tab receiving groove being provided with the second active material layer; a first tab, partially received in the first tab receiving groove, the first tab having a first portion overlapping the first empty foil region, the first portion being welded with the first empty foil region to form a first weld; a second tab opposite in polarity to the first tab, the second tab including a second tab segment, the second tab segment being oppositely arranged to the first tab segment along the first direction and facing the second surface, the second tab including a second current collector; a first insulating member arranged between the second active material layer and the second current collector of the second tab segment, the first insulating member covering the first weld as viewed along the first direction.

2. The electric cell of claim 1, wherein, Along a length direction of the first tab segment, a dimension of the first insulating member is W1, a dimension of the first weld is W'3, and a dimension of the first tab receiving groove is K; along a width direction of the first tab segment, a dimension of the first insulating member is L1, a dimension of the first weld is L'3, and a dimension of the first tab receiving groove is G, W'3 < W1 < K, and L'3 < L1 < G.

3. The electric cell of claim 2, wherein, Along the length direction of the first tab segment, a dimension of the first portion is W3; along the width direction of the first tab segment, a dimension of the first portion is L3, W3 < W1, and L3 < L1.

4. The electric cell of claim 1, wherein, One of the first tab and the second tab is a positive electrode tab, and the first insulating member is arranged on the positive electrode tab.

5. The electric cell of claim 1, wherein, The first tab is a positive electrode tab, the second active material layer is provided with a first receiving groove facing a surface of the second tab segment, and the first insulating member is at least partially arranged in the first receiving groove.

6. The electric cell of claim 5, wherein, Along the first direction, a depth of the first receiving groove is less than a thickness of the second active material layer.

7. The electric cell of claim 5, wherein, Along the length direction of the first tab segment, a dimension of the first insulating member is W1, and a dimension of the first receiving groove is W2; along the width direction of the first tab segment, a dimension of the first insulating member is L1, and a dimension of the first receiving groove is L2, 0.1 mm ≤ W2-W1 ≤ 2 mm, and 0.1 mm ≤ L2-L1 ≤ 2 mm.

8. The electric cell of claim 1, wherein, The second tab is a positive electrode tab, the second tab segment including a second current collector and a third active material layer, the third active material layer being arranged on a surface of the second current collector facing the first tab segment; The third active material layer is provided with a first receiving groove facing a surface of the first tab segment, and the first insulating member is at least partially arranged in the first receiving groove.

9. The electric cell of claim 8, wherein, The first accommodating groove has a depth less than a thickness of the third active material layer.

10. The electric cell of claim 8, wherein, In a length direction of the second pole piece segment, the first insulating member has a dimension W1 and the first accommodating groove has a dimension W2, and in a width direction of the second pole piece segment, the first insulating member has a dimension L1 and the first accommodating groove has a dimension L2, 0.1mm≤W2-W1≤4mm, and 0.1mm≤L2-L1≤3mm.

11. The cell of any of claims 5-10, wherein, The first accommodating groove has a depth greater than or equal to a thickness of the first insulating member.

12. The electric cell of claim 11, wherein, The first accommodating groove has a depth T1 and the first insulating member has a thickness C1, 0.1μm≤T1-C1≤10μm.

13. The electric cell of claim 4, wherein, The first pole piece is a positive pole piece, in a length direction of the first pole piece segment, the first weld mark has a dimension W'3 and the first insulating member has a dimension W1, and in a width direction of the first pole piece segment, the first weld mark has a dimension L'3 and the first insulating member has a dimension L1, 0.1mm≤L'3≤3mm, and 0.1mm≤L1-L'3≤3mm.

14. The electric cell of claim 4, wherein, The first pole piece is a negative pole piece, in a length direction of the first pole piece segment, the first weld mark has a dimension W'2 and the first insulating member has a dimension W1, and in a width direction of the first pole piece segment, the first weld mark has a dimension L'2 and the first insulating member has a dimension L1, 0.1mm≤W1-W'2≤5mm, and 0.1mm≤L1-L'2≤3mm.

15. The electrically core of claim 1, wherein, The second pole piece further comprises a third pole piece segment, and the first pole piece segment is located between the second pole piece segment and the third pole piece segment. The third pole piece segment comprises a third current collector and a fourth active material layer, the fourth active material layer is arranged on a surface of the third current collector facing the first pole piece segment, a surface of the fourth active material layer facing the first pole piece segment is provided with a second accommodating groove, and projections of the first portion and the first insulating member are both located in the second accommodating groove as viewed in the first direction.

16. The electric cell of claim 15, wherein, In a length direction of the first pole piece segment, the first insulating member has a dimension W1 and the second accommodating groove has a dimension W4, and in a width direction of the first pole piece segment, the first insulating member has a dimension L1 and the second accommodating groove has a dimension L4, 0.1mm≤W4-W1≤6mm, and 0.1mm≤L4-L1≤5mm.

17. The electric cell of claim 15, wherein, The battery cell further comprises a second insulating member, the second insulating member is at least partially accommodated in the second accommodating groove, and the second insulating member covers the first weld mark as viewed in the first direction.

18. The electric cell of claim 17, wherein, The second accommodating groove comprises a first groove segment and a second groove segment, the first groove segment is closer to the third current collector than the second groove segment, groove side surfaces of the first groove segment and the second groove segment are connected by a first step surface, the second insulating member is accommodated in the second groove segment and connected to the first step surface, and a projection of the first portion is located in the first groove segment as viewed in the first direction.

19. The electric cell of claim 17, wherein, In a width direction of the first pole piece, the second insulating member extends beyond an end of the third pole piece segment close to the first tab.

20. The electrically core of claim 15, wherein, The electric core further comprises a third insulating member connected to the first tab and located between the first current collector and the third current collector, the third insulating member covering the first welding spot.

21. The electrically cell of claim 20, wherein, The first tab receiving groove comprises a third groove segment and a fourth groove segment, the third groove segment being closer to the first current collector than the fourth groove segment, groove sides of the third groove segment and the fourth groove segment being connected by a second step surface, the third insulating member being at least partially received in the fourth groove segment and connected to the second step surface.

22. The electrically core of claim 1, wherein, The first portion and the first empty foil area are connected by laser welding.

23. The electrically core of claim 1, wherein, The electric core comprises a separator disposed between the first tab and the second tab, the first insulating member being disposed on the separator.

24. The electrically cell of claim 23, wherein, The first tab adjacent to the first insulating member is provided with a first receiving groove, in the first direction, a projection of the first insulating member being located within a projection of the first receiving groove; the first receiving groove is disposed on the second active material layer of the first tab facing the first insulating member, or The second tab adjacent to the first insulating member is provided with a first receiving groove, in the first direction, a projection of the first insulating member being located within a projection of the first receiving groove; the first receiving groove is disposed on the active material layer of the second tab facing the first insulating member.

25. An electric device comprising the electric core according to any one of claims 1-24.

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