Single battery and battery pack

Abstract

The utility model discloses a single battery and a battery pack, and belongs to the technical field of batteries, the single battery comprises a cover plate assembly, the cover plate assembly comprises a cover plate body and a pole, an electrode assembly comprises an electrode body and a tab structure connected with the electrode body, the tab structure comprises a plurality of tabs which are arranged in a stacked manner, each tab is provided with an indentation, and the indentation is arranged between the tabs. All the tabs and the pole columns are welded and form welding marks, the tab structure is provided with a first surface and a second surface which are arranged back to back in the stacking direction of the tabs, and the pole columns are welded with the tab structure on the second surface; wherein the welding mark covers at least one part of indentation of the tab on the first surface. By arranging the indentation on each tab, the strength of the tab structure is enhanced, the tab is prevented from being folded, and the indentation can play a role in indicating the welding position of the tab structure and the pole, so that the welding operation is convenient.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of single batteries, and particularly relates to a single battery and a battery pack. BACKGROUND

[0002] In recent years, with the rapid development of the new energy industry, the requirement for the energy density of lithium ion batteries is also higher and higher. At present, the energy density of the battery is mainly improved by reducing the thickness of the foil and increasing the thickness of the pole piece, or increasing the proportion of active substances in the aluminum shell.

[0003] However, the energy density of the battery is improved by reducing the thickness of the foil and increasing the thickness of the pole piece, which makes the tab more soft and thin, which leads to the inconvenience of welding between the tabs and the welding operation between the tabs and the pole. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims at solving the technical problems of tab deformation and inconvenient welding.

[0005] Technical scheme: The utility model provides a single battery, which comprises:

[0006] A shell body has a containing cavity;

[0007] A cover plate assembly comprises a cover plate body and a pole, the cover plate body is connected with the shell body and covers the containing cavity, and the pole is arranged in the cover plate body;

[0008] An electrode assembly is arranged in the containing cavity, the electrode assembly comprises an electrode body and a tab structure connected with the electrode body, the tab structure comprises a plurality of tabs arranged in layers, and each tab is provided with an indentation;

[0009] The electrode assembly has a first direction, the first direction is the layering direction of the tabs, the tab structure has a first surface and a second surface arranged opposite to each other in the first direction, all the tabs and the pole are welded and form a welding mark, the welding mark covers at least part of the indentation of the tab located on the first surface, and the pole is welded with the tab structure on the second surface.

[0010] In some embodiments, the welding mark covers part of the indentation of the tab located on the second surface.

[0011] In some embodiments, the tab structure is a full tab structure, the electrode body has an end face close to the cover plate body, the full tab structure is arranged between the end face and the cover plate body, the welding mark extends in a straight line on the first surface and is parallel to the end face, the electrode assembly has a second direction intersecting with the first direction, the second direction is the extension direction of the tab, along the second direction, part of the welding mark located on the first surface and the end face has a size L mm, the thickness of the electrode body in the first direction is M mm, and 0.5<=L-M<=4.5 is satisfied.

[0012] In some embodiments, the tab structure is a half-tab structure, the electrode body has an end face close to the cover body, the half-tab structure is arranged between the end face and the cover body, the welding mark extends in a straight line on the first face and is parallel to the end face, the electrode assembly has a second direction intersecting the first direction, the second direction is the extension direction of the tab, along the second direction, the welding mark and the end face are separated by a size L mm, the thickness of the electrode body in the first direction is M mm, and 0.5≤L-M / 2≤4.5 is satisfied.

[0013] In some embodiments, the tab structure includes a bending part and a connecting part, the bending part is located between the electrode body and the connecting part and is connected with the electrode body and the connecting part respectively, the connecting part is connected with the post, and at least part of the indentation on the second face and the welding mark are located in the connecting part.

[0014] In some embodiments, the indentation on the first face has opposite first and second ends, the electrode assembly has a second direction intersecting the first direction, the second direction is the extension direction of the tab, along the second direction, in the second direction, the first end is located between the second end and the electrode body, and the welding mark covers at least part of the first end.

[0015] In some embodiments, the indentation on the first face has a plurality of point-like indentations, the electrode assembly has a third direction intersecting the first direction, the third direction is the extension direction of the welding mark on the first face, the plurality of point-like indentations are arranged at intervals along the third direction, and at least part of the plurality of point-like indentations are covered by the welding mark.

[0016] In some embodiments, the indentation on the first face has a plurality of linear indentations, each linear indentation extends along a straight line, at least one linear indentation intersects the welding mark or one linear indentation coincides with the welding mark.

[0017] In some embodiments, the indentation on the first face has at least one planar indentation, the welding mark covers at least part of the planar indentation, and the shape of the planar indentation is one of a polygon, a circle, a semicircle, and an ellipse.

[0018] Correspondingly, the embodiments of the present application provide a battery pack including the monomer battery.

[0019] Beneficial effects: the single battery of the embodiment of the application comprises a shell, a cover plate assembly and an electrode assembly; the shell has a containing cavity; the cover plate assembly comprises a cover plate body and a pole, the cover plate body is connected with the shell and covers the containing cavity, and the pole is arranged in the cover plate body; the electrode assembly is arranged in the containing cavity, and the electrode assembly comprises an electrode body and a tab structure connected with the electrode body, the tab structure comprises a plurality of tabs arranged in layers, each tab is provided with an indentation, all the tabs and the pole are welded and have a welding mark, and the electrode assembly has a first direction, the first direction is a layering direction of the tabs, the tab structure has a first surface and a second surface arranged opposite to each other in the first direction, the welding mark covers at least part of the indentations of the tabs on the first surface, and the pole is welded with the tab structure on the second surface. In this way, by arranging the indentations on each tab, the tabs are not easy to deform, and the strength of the tab structure can be enhanced; meanwhile, the indentations on the first surface can indicate the welding position of the tab structure and the pole, so that the welding position corresponds to the position of the indentations, and the welding operation is facilitated.

[0020] The battery pack of the embodiment of the application comprises the single battery described above, and therefore can have all the technical features and beneficial effects of the single battery described above, which will not be described herein again. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort.

[0022] Figure 1 is a structural schematic view of a first tab and an indentation of the embodiment of the application;

[0023] Figure 2 is a structural schematic view of a first tab, an indentation and a welding mark of the embodiment of the application;

[0024] Figure 3 is a structural schematic view of a second tab and an indentation of the embodiment of the application;

[0025] Figure 4 is a structural schematic view of a second tab, an indentation and a welding mark of the embodiment of the application;

[0026] Figure 5 is a structural schematic view of a third tab and an indentation of the embodiment of the application;

[0027] Figure 6 is a structural schematic view of a third tab, an indentation and a welding mark of the embodiment of the application;

[0028] Figure 7 is a structural schematic diagram of a fourth tab and indentation of an embodiment of the present application;

[0029] Figure 8 is a structural schematic diagram of a fourth tab, indentation and welding mark of an embodiment of the present application;

[0030] Figure 9 is a structural schematic diagram of a fifth tab and indentation of an embodiment of the present application;

[0031] Figure 10 is a structural schematic diagram of a fifth tab, indentation and welding mark of an embodiment of the present application;

[0032] Figure 11 is a structural schematic diagram of a sixth tab and indentation of an embodiment of the present application;

[0033] Figure 12 is a structural schematic diagram of a sixth tab, indentation and welding mark of an embodiment of the present application;

[0034] Figure 13 is a structural schematic diagram of a first electrode assembly of an embodiment of the present application;

[0035] Figure 14 is a structural schematic diagram of a second electrode assembly of an embodiment of the present application;

[0036] Figure 15 is a structural schematic diagram of a single cell of an embodiment of the present application;

[0037] Figure 16 is a structural schematic diagram of two electrode assemblies assembled of an embodiment of the present application.

[0038] Reference signs: 1, housing; 2, cover plate assembly; 3, electrode assembly; 20, cover plate body; 21, pole post; 30, electrode body; 31, tab structure; 32, full tab structure; 33, half tab structure; 300, end face; 310, indentation; 311, welding mark; 312, first face; 313, second face; 314, bent portion; 315, connecting portion; 316, tab; 3100, first end; 3101, second end; 3102, dot-shaped indentation; 3103, linear indentation; 3104, planar indentation; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0039] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative work fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, at least one of which can be one, two or more, unless otherwise explicitly specified. In the description of the present application, "vertical" means completely vertical at 90° or almost completely vertical, for example, within the range of 80°-100°, it is considered as vertical, similarly, "parallel" means completely parallel or almost completely parallel, for example, within the range of 10° of complete parallel, it is considered as parallel.

[0041] The applicant has noticed that in recent years, with the rapid development of new energy industry, the requirement for energy density of lithium ion batteries is increasing. At present, the energy density of the battery is mainly improved by reducing the thickness of the foil and increasing the thickness of the pole piece, or increasing the proportion of active material in the aluminum shell. However, by reducing the thickness of the foil and increasing the thickness of the pole piece to improve the energy density of the battery, the tab will be more soft and thin, which will further cause the tab to deform and the welding to be inconvenient.

[0042] Therefore, the single battery of the embodiment of the present application comprises a shell, a cover plate assembly and an electrode assembly; the shell has a containing cavity; the cover plate assembly comprises a cover plate body and a pole, the cover plate body is connected with the shell and covers the containing cavity, and the pole is arranged in the cover plate body; the electrode assembly is arranged in the containing cavity, and comprises an electrode body and a tab structure connected with the electrode body; the tab structure comprises a plurality of tabs arranged in layers, each tab is provided with an indentation, all the tabs and the pole are welded and have a welding mark, the electrode assembly has a first direction, the first direction is the layering direction of the tabs, the tab structure has a first surface and a second surface arranged opposite in the first direction, and the pole is welded with the tab structure at the second surface; wherein the welding mark covers at least part of the indentations of the tabs at the first surface, and the welding mark covers at least part of the indentations in the layering direction of the tabs. In this way, by arranging the indentations on each tab, the tabs are less likely to be deformed, the strength of the tab structure can be enhanced, and the tabs are less likely to be folded; meanwhile, the indentations at the first surface can indicate the welding position of the tab structure and the pole, so that the welding position corresponds to the position of the indentations, and the welding operation is facilitated.

[0043] The single battery and the battery pack of the present application will be described in detail below with reference to the accompanying drawings. The features in the following embodiments and implementation manners can be combined with each other without conflict.

[0044] Figure 1 is a structural schematic view of a first tab 316 and an indentation 310 according to an embodiment of the present application; Figure 2 is a structural schematic view of a first tab 316, an indentation 310 and a welding mark 311 according to an embodiment of the present application; Figure 3 is a structural schematic view of a second tab 316 and an indentation 310 according to an embodiment of the present application; Figure 4 is a structural schematic view of a second tab 316, an indentation 310 and a welding mark 311 according to an embodiment of the present application; Figure 5 is a structural schematic view of a third tab 316 and an indentation 310 according to an embodiment of the present application; Figure 6 is a structural schematic view of a third tab 316, an indentation 310 and a welding mark 311 according to an embodiment of the present application; Figure 7 is a structural schematic view of a fourth tab 316 and an indentation 310 according to an embodiment of the present application; Figure 8 is a structural schematic view of a fourth tab 316, an indentation 310 and a welding mark 311 according to an embodiment of the present application; Figure 9 is a structural schematic view of a fifth tab 316 and an indentation 310 according to an embodiment of the present application; Figure 10 is a structural schematic view of a fifth tab 316, an indentation 310 and a welding mark 311 according to an embodiment of the present application; Figure 11 is a structural schematic view of a sixth tab 316 and an indentation 310 according to an embodiment of the present application; Figure 12is a structural schematic diagram of the sixth tab 316, indentation 310 and welding mark 311 of the embodiment of the present application; Figure 13 is a schematic diagram of the tab structure 31 of the first electrode assembly 3 of the embodiment of the present application; Figure 14 is a schematic diagram of the tab structure 31 of the second electrode assembly 3 of the embodiment of the present application; Figure 15 is a structural schematic diagram of a single battery of the embodiment of the present application; Figure 16 is a structural schematic diagram of the assembly of two electrode assemblies 3 of the embodiment of the present application.

[0045] Reference Figures 1 to 16 The embodiment of the present application provides a single battery, which comprises a shell, a cover plate assembly 2 and an electrode assembly 3; the shell 1 has a containing cavity; the cover plate assembly 2 comprises a cover plate body 20 and a pole 21, the cover plate body 20 is connected with the shell 1 and covers and seals the containing cavity, and the pole 21 is arranged in the cover plate body 20; the electrode assembly 3 is arranged in the containing cavity, the electrode assembly 3 comprises an electrode body 30 and a tab structure 31 connected with the electrode body 30, the tab structure 31 comprises a plurality of tabs 316 arranged in layers, each tab 316 is provided with an indentation 310, all the tabs 316 and the pole 21 are welded and formed with a welding mark 311, the electrode assembly 3 has a first direction X, the first direction X is the layering direction of the tabs 316, the tab structure 31 has a first surface 312 and a second surface 313 arranged oppositely in the first direction X, and the pole 21 is welded with the tab structure 31 at the second surface 313; wherein the welding mark 311 covers at least part of the indentation 310 of the tab 316 located at the first surface 312. The welding mark 311 covers at least part of the indentation 310 in the layering direction of the tab 316, i.e. the first direction X.

[0046] In some embodiments, in the preparation process of the single battery, the electrode assembly 3 is prepared by a rolling process, and the electrode assembly 3 rolled is cut into the tab structure 31 according to the design requirements. In the die cutting process of the tab structure 31, a pressure marking pattern operation is performed, that is, the indentation 310 is formed on each tab 316 along the first direction X, and the indentation 310 is generally a pressure groove, such as Figures 1 to 12The electrode assembly 3 is then hot-pressed to reduce internal voids and increase the energy density of the single battery. After the hot-pressing is completed, the tab structure 31 and the pole 21 are welded to form a weld 311 based on the indentation 310 on the tab 316, the weld 311 covering at least part of the indentation 310 in the thickness direction of the tab 316. The indentation 310 serves as an indication of the welding position, which is used as a reference position during welding, so that the tabs 316 can be more accurately welded between the tabs 316 and between the tab structure 31 and the pole 21. The electrode assembly 3 and the cover assembly 2 are assembled in the shell 1, and the sealing assembly of the shell 1 and the cover assembly 2 is completed. In this way, by providing the indentation 310 on each tab 316, the strength of the tab structure 31 can be enhanced, and the tab 316 is less likely to deform. At the same time, the indentation 310 on the first surface 312 can serve as an indication of the welding position of the tab structure 31 and the pole 21, making the welding operation more convenient, improving the production efficiency, and improving the safety and reliability of the single battery.

[0047] In some embodiments, along the first direction X, the welding mark 311 covers a part of the indentation 310 on the tab 316 of the second surface 313. That is, the welding mark 311 covers a part of the indentation 310 on the second surface 313, while another part of the indentation 310 is not covered. It is to be noted that for the indentation 310 of the first surface 312, it is required that the welding mark 311 covers at least a part of the indentation 310 on the tab 316 of the first surface 312, and the indentation 310 of the first surface 312 is used to accurately position the welding position, so as to ensure the good yield of the electrode assembly 3 into the shell. For the indentation 310 of the second surface 313, since the indentation 310 formed in the die-cutting process of the tab structure 31 is generated in the initial state where the tab structure 31 is not folded, that is, before welding, all the indentations 310 are nested and overlapped with each other; and when welding, the welding head presses the tab 316 from the first surface 312, so that all the tabs 316 are stacked together, and since one end of the tab 316 is connected to the electrode body 30, the pressing force of the welding head will make the tab 316 of the first surface 312 bend towards the second surface 313, and the tab 316 closer to the second surface 313 bends less, showing a trend that the tabs 316 stacked in the direction from the first surface 312 to the second surface 313, i.e. the first direction X, bend less and less, and eventually lead to the fact that the indentations 310 of different tabs 316 do not completely correspond in the first direction X, but are misaligned. When all the tabs 316 are welded to form the tab structure 31, and then the pole 21 is welded to the second surface 313 of the tab structure 31, at this time, the welding is still carried out with the indentation 310 of the first surface 312 as a reference, that is, the welding between the tab structure 31 and the pole 21 is carried out along the part of the welding mark 311 formed on the tab structure 31, so as to form another part of the welding mark 311. Therefore, the final position of the welding mark 311 does not completely overlap with the indentation 310 of the second surface 313 in the first direction X, and thus the welding mark 311 covers a part of the indentation 310 on the tab 316 of the second surface 313.

[0048] The applicant also found that when the tab 316 becomes more soft and thin, the tab 316 will become more prone to breakage, and when welding the stacked multiple tabs 316, the tab 316 is easily pulled off from the electrode body 30 due to the pressing of the welding head, and then the tab 316 is torn, which affects the overcurrent capacity of the battery, and the debris generated by the breakage can also cause short circuit; and after all the tabs 316 and the pole 21 are welded, the cover assembly 2 is covered on the shell 1, and since the tab 316 is more soft and thin, the tab 316 is more prone to folding or elongation due to the pressure of the cover body 20 towards the electrode body 30, and then the folded tab 316 is inserted into the electrode body 30, which can cause short circuit of the electrode body 30 and other problems.

[0049] Therefore, in order to solve the above problems, the electrode assembly 3 is provided with a cover assembly 2. Figure 2 ,Figure 4 、 Figure 6 、 Figure 8 、 Figure 10 、 Figure 12 and Figure 13 In the embodiment shown in FIG. 31, the tab structure 31 is a full tab structure 32, and the electrode body 30 leads out the tab structure 31 by a full tab leading-out mode. It can be understood that when the electrode body 30 is of a winding type, two tabs 316 are symmetrically arranged on each coil of the electrode body 30 with the diameter of the electrode body 30 as the center of symmetry. The electrode body 30 has an end face 300 close to the cover body 20, and the full tab structure 32 is arranged between the end face 300 and the cover body 20. The welding marks 311 extend in a straight line on the first face 312 and are parallel to the end face 300. The electrode assembly 3 has a second direction Y intersecting the first direction X, and the second direction Y is the extension direction of the tabs 316. Along the second direction Y, the welding marks 311 located between the first face 312 and the end face 300 have a size L mm, and the thickness of the electrode body 30 in the first direction X is M mm, which satisfies: 0.5≤L-M≤4.5.

[0050] It can be understood that the present application limits the range of L-M to ensure that the distance between the welding marks 311 and the roots of the tabs 316 is within a suitable range. On the one hand, it avoids the welding marks 311 at the welding position being too close to the end face 300 of the electrode body 30, which causes the tabs 316 to be pulled off. On the other hand, it avoids the tabs 316 of the tab structure 31 after welding being folded or redundant after the cover body 20 seals the shell 1, thereby improving the safety and reliability of the single battery.

[0051] In the embodiments of the present application, the full tab structure 32 is welded with the pole 21 by the preparation process of the single battery described above. Each group of embodiments selects 30 single batteries, and the specific structural parameters and performance test results after welding are shown in Table 1.

[0052] Table 1:

[0053]

[0054] It should be noted that the number of folds, the number of tear layers, and whether the tabs 316 are redundant can be obtained by visual inspection, cross-section judgment, or ultrasonic detection. A fold is considered to have a fold as long as it appears. The number of single batteries with folds is divided by the total number of single batteries to obtain the tab folding ratio. Similarly, a tear is considered to have a tear as long as it appears. The number of single batteries with tears is divided by the total number of single batteries to obtain the tab tearing ratio. A redundancy is considered to have a redundancy as long as it appears. The number of single batteries with redundancies is divided by the total number of single batteries to obtain the redundancy ratio (the judgment method in Table 2 is the same, and will not be described again).

[0055] As can be seen from Table 1, due to the presence of the indentation 310 on the tab 316, the strength of the tab 316 is increased, and no folding occurs. In Embodiments 1 to 3, the difference between the dimension L of the weld mark 311 on the first face 312 and the thickness M of the electrode body 30 along the extension direction of the tab 316 is less than 0.5, i.e., the distance between the weld mark 311 and the root of the tab 316 is close, which is easy to cause the tab 316 to be torn during welding of the welding head. In Embodiments 10 and 11, the difference between the dimension L of the weld mark 311 on the first face 312 and the thickness M of the electrode body 30 along the extension direction of the tab 316 is greater than 4.5, i.e., the distance between the weld mark 311 and the root of the tab 316 is far, and after the cover body 20 is assembled with the shell 1, the tab 316 is easy to be redundant and cause reverse insertion. However, in Embodiments 4 to 9, the difference between the dimension L of the weld mark 311 on the first face 312 and the thickness M of the electrode body 30 along the extension direction of the tab 316, i.e., the second direction Y, satisfies 0.5≤L-M≤4.5, by limiting the range of L-M, to ensure that the distance between the weld mark 311 and the root of the tab 316 is within a suitable range, which can not only avoid tearing and breaking of the tab 316 during welding, but also avoid reverse insertion of the tab 316 into the electrode body 30 due to the downward pressure of the cover body 20 after the cover body 20 is assembled.

[0056] In Figure 2 , Figure 4 , Figure 6 , Figure 8 , Figure 10 , Figure 12 and Figure 14 In the embodiments shown in FIGS. 1 to 5, the tab structure 31 is a full tab structure 32, and the electrode body 30 leads out the tab structure 31 by a full tab leading-out mode. It can be understood that when the electrode body 30 is a winding type, each coil of the electrode body 30 leads out two tabs 316. The electrode body 30 has an end face 300 close to the cover body 20, the tab structure 32 is arranged between the end face 300 and the cover body 20, the weld mark 311 extends linearly on the first face 312 and is parallel to the end face 300, the electrode assembly 3 has a second direction Y, the second direction Y intersects the first direction X, the second direction Y is the extension direction of the tab 316, along the second direction Y, the dimension L between the weld mark 311 on the first face 312 and the end face 300 is greater than 4.5 mm, the thickness of the electrode body 30 in the first direction X is M mm, and the following condition is satisfied: 0.5≤L-M / 2≤4.5.

[0057] It can be understood that, by limiting the range of L-M / 2, the application ensures that the distance between the welding mark 311 and the root of the tab 316 is within a proper range, on the one hand, avoiding the welding mark 311 of the welding position being too close to the end face 300 of the electrode body 30 to cause the tab 316 to be torn off, and on the other hand, avoiding the tab 316 of the tab structure 31 after welding from being inserted upside down due to folding / lengthening after the cover body 20 is sealed to the shell 1.

[0058] In the embodiments of the application, the half-tab structure 33 is welded to the pole 21 by using the preparation process of the single battery described above, and the specific structural parameters and the performance test results after welding are shown in Table 2.

[0059] Table 2:

[0060]

[0061] As can be seen from Table 2, due to the indentation 310 provided on the tab 316, the strength of the tab 316 is increased, and no folding occurs. In the embodiment 12 to the embodiment 14, L-M / 2<0.5, that is, the distance between the welding mark 311 and the root of the tab 316 is relatively close, which is easy to cause some tabs 316 to be torn during welding of the welding head. In the embodiment 21 and the embodiment 22, L-M / 2>4.5, that is, the distance between the welding mark 311 and the root of the tab 316 is relatively far, and when the cover body 20 is assembled to the shell 1, the tab 316 is easy to be redundant and cause the tab to be inserted upside down. However, in the embodiment 15 to the embodiment 20, L-M / 2 satisfies 0.5≤L-M / 2≤4.5, by limiting the range of L-M / 2, the distance between the welding mark 311 and the root of the tab 316 is ensured to be within a proper range, which can not only avoid the tab 316 from being torn or broken during welding, but also avoid the tab 316 from being inserted upside down after the cover body 20 is assembled due to the pressing of the cover body 20.

[0062] In Figure 16 In the embodiments shown in the drawings, the tab structure 31 includes a bending part 314 and a connecting part 315, the bending part 314 is located between the electrode body 30 and the connecting part 315 and is connected with the electrode body 30 and the connecting part 315 respectively, the connecting part 315 is connected with the pole 21, and at least part of the indentation 310 and the welding mark 311 of the second face 313 are located in the connecting part 315.

[0063] When welding, the welding head is pressed against the laminated tab 316 by the first surface 312. Since the tab 316 extends out of the electrode body 30 in the second direction Y, after being pressed, the part of the tab 316 connected to the electrode body 30 will be pulled, and the plurality of tabs 316 will be pulled and form the bending portion 314. The bending portion 314 also enables the tab structure 31 to deform when the tab structure 31 is welded to the pole 21 and when the cover body 20 is pressed down, thereby improving the fault tolerance during assembly. In addition, the bending portion 314 is located between the electrode body 30 and the connecting portion 315, and also enables the transition between the electrode body 30 and the connecting portion 315, so as to adapt to different stress changes, thereby improving the safety and reliability of the single battery. At least part of the welding mark 311 and the indentation 310 are arranged on the connecting portion 315, so as to realize welding with the pole 21 on the connecting portion 315, and further realize electrical connection between the electrode body 30 and the pole 21, thereby ensuring that the single battery can normally perform charging and discharging operations.

[0064] In some embodiments, the indentation 310 on the first surface 312 has opposite first and second ends 3100 and 3101, the electrode assembly 3 has a second direction Y intersecting the first direction X, the second direction Y being the extension direction of the tab 316, in the second direction Y, the first end 3100 is located between the second end 3101 and the electrode body 30, and the welding mark 311 covers at least part of the first end 3100. Figure 6 、 Figure 8 and Figure 10 In the embodiments shown in

[0065] In some embodiments, the indentation 310 on the first surface 312 has a plurality of point-like indentations 3102, the electrode assembly 3 has a third direction Z intersecting the first direction X, the third direction Z being the extension direction of the welding mark 311 on the first surface 312, the plurality of point-like indentations 3102 are arranged at intervals along the third direction Z, and at least part of the point-like indentations 3102 are covered by the welding mark 311. Exemplarily, in Figure 3 and Figure 4In the illustrated embodiment, the plurality of point-like indentations 3102 are arranged along the third direction Z at intervals to indicate the welding position of the tab structure 31 and the pole 21, prevent the partial tab 316 from cracking after welding of the tab structure 31, and prevent the problem of reverse insertion caused by lengthiness, thereby ensuring the yield of the electrode assembly 3 into the case, improving the production efficiency, and improving the safety and reliability of the single battery.

[0066] In some embodiments, the indentation 310 on the first surface 312 has a plurality of linear indentations 3103, each of which extends along a straight line, and at least one of the linear indentations 3103 intersects the welding mark 311 or one of the linear indentations 3103 coincides with the welding mark 311.

[0067] In Figure 1 and Figure 2 In the illustrated embodiment, the plurality of linear indentations 3103 extend along the second direction Y and the third direction Z, respectively, and the welding mark 311 partially coincides with the linear indentation 3103 extending along the third direction Z. By arranging the linear indentation 3103 along the third direction Z, on the one hand, the strength of the tab structure 31 can be enhanced to prevent the tab 316 from being folded; on the other hand, the welding position of the tab structure 31 and the pole 21 can be indicated to prevent the partial tab 316 from cracking after welding of the tab structure 31, the problem of reverse insertion caused by lengthiness, and ensure the yield of the electrode assembly 3 into the case, thereby improving the production efficiency and the safety and reliability of the single battery.

[0068] In Figure 5 and Figure 6 In the illustrated embodiment, the plurality of linear indentations 3103 extend along a direction inclined with respect to the second direction Y or the third direction Z and are sequentially connected, and the endpoints of the plurality of linear indentations 3103 are arranged at intervals along the third direction Z, which can be used to indicate the welding position of the tab structure 31 and the pole 21, prevent the partial tab 316 from cracking after welding of the tab structure 31, and prevent the problem of reverse insertion caused by lengthiness, thereby ensuring the yield of the electrode assembly 3 into the case, improving the production efficiency, and improving the safety and reliability of the single battery.

[0069] In some embodiments, the indentation 310 on the first surface 312 has at least one planar indentation 3104, the welding mark 311 covers at least part of the planar indentation 3104, and the shape of the planar indentation 3104 is one of a polygon, a circle, a semicircle, and an ellipse, which is not limited in the present application.

[0070] In Figure 7 and Figure 8In the illustrated embodiment, a plurality of triangular surface indentations 3104 are arranged in the middle of the tab structure 31. In this way, on the one hand, the strength of the tab structure 31 can be enhanced, and the problem of tab 316 folding can be prevented; on the other hand, the triangular side close to the electrode body 30 extends in the third direction Z, and the welding mark 311 coincides with the triangular surface indentation 3104 close to the electrode body 30, which can indicate the welding position of the tab structure 31 and the pole 21, prevent the tab structure 31 from cracking after welding, and prevent the problem of reverse insertion caused by the length, ensure the yield of the electrode assembly 3 into the shell, and improve the production efficiency and the safety and reliability of the single battery.

[0071] In Figure 9 and Figure 10 In the illustrated embodiment, a plurality of triangular surface indentations 3104 are arranged in the middle of the tab structure 31. In this way, on the one hand, the strength of the tab structure 31 can be enhanced, and the problem of tab 316 folding can be prevented; on the other hand, the triangular side close to the electrode body 30 extends in the third direction Z, and the welding mark 311 coincides with the triangular surface indentation 3104 close to the electrode body 30, which can indicate the welding position of the tab structure 31 and the pole 21, prevent the tab structure 31 from cracking after welding, and prevent the problem of reverse insertion caused by the length, ensure the yield of the electrode assembly 3 into the shell, and improve the production efficiency and the safety and reliability of the single battery.

[0072] In Figure 11 and Figure 12 In the illustrated embodiment, a plurality of triangular surface indentations 3104 are arranged in the middle of the tab structure 31. In this way, on the one hand, the strength of the tab structure 31 can be enhanced, and the problem of tab 316 folding can be prevented; on the other hand, the triangular side close to the electrode body 30 extends in the third direction Z, and the welding mark 311 coincides with the triangular surface indentation 3104 close to the electrode body 30, which can indicate the welding position of the tab structure 31 and the pole 21, prevent the tab structure 31 from cracking after welding, and prevent the problem of reverse insertion caused by the length, ensure the yield of the electrode assembly 3 into the shell, and improve the production efficiency and the safety and reliability of the single battery.

[0073] It should be noted that the point-like indentation 3102 described in the present application refers to the indentation 310 which is a point-like groove arranged on the surface of the tab 316. The linear indentation 3103 refers to the indentation 310 which is a linear groove extending on the surface of the tab 316. The surface indentation 3104 refers to the indentation 310 which is neither point-like nor linear, but the groove bottom has a certain area, so that the indentation 310 occupies a region of the surface of the tab 316.

[0074] In some embodiments, the monomer battery refers to a basic unit capable of realizing mutual conversion between chemical energy and electrical energy, and can be used to manufacture a battery or a battery pack, thereby being used to supply power to an electrical device or an energy storage device.

[0075] In some embodiments, the monomer battery can be a secondary battery monomer, which refers to a battery monomer that can be activated by charging after the battery monomer is discharged, and can be used continuously.

[0076] Correspondingly, the embodiments of the present application provide a battery pack comprising the monomer battery described above. The battery pack can be a single physical module comprising one or more monomer batteries to provide higher voltage and capacity. When the monomer batteries are multiple, the multiple monomer batteries can be connected in series, in parallel or in a mixed manner.

[0077] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0078] The monomer battery and the battery pack provided by the embodiments of the present application are described in detail above, and the principles and implementation manners of the present application are described by applying specific examples. The above embodiment descriptions are only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A single cell, characterized by, The application relates to a battery, comprising: a shell having a receiving cavity; a cover plate assembly comprising a cover plate body and a pole, the cover plate body being connected with the shell and covering the receiving cavity, and the pole being arranged in the cover plate body; an electrode assembly arranged in the receiving cavity, the electrode assembly comprising an electrode body and a tab structure connected with the electrode body, the tab structure comprising a plurality of tabs arranged in a stack, each of the tabs being provided with an indentation; the electrode assembly has a first direction, which is a stacking direction of the tabs, the tab structure has a first surface and a second surface arranged opposite to each other in the first direction, all the tabs and the pole are welded and form a weld, and the weld covers at least part of the indentations of the tabs on the first surface, and the pole is welded with the tab structure on the second surface.

2. The cell according to claim 1, wherein The weld covers part of the indentations of the tabs on the second surface.

3. The cell according to claim 1, wherein The tab structure is a full-tab structure, the electrode body has an end surface close to the cover plate body, the full-tab structure is arranged between the end surface and the cover plate body, the weld extends linearly on the first surface and is parallel to the end surface, the electrode assembly has a second direction intersecting the first direction, the second direction is an extension direction of the tabs, along the second direction, a distance between the weld on the first surface and the end surface is L mm, a thickness of the electrode body in the first direction is M mm, and 0.5<=L-M<=4.5 is satisfied.

4. The cell according to claim 1, wherein The tab structure is a half-tab structure, the electrode body has an end surface close to the cover plate body, the half-tab structure is arranged between the end surface and the cover plate body, the weld extends linearly on the first surface and is parallel to the end surface, the electrode assembly has a second direction intersecting the first direction, the second direction is an extension direction of the tabs, along the second direction, a distance between the weld on the first surface and the end surface is L mm, a thickness of the electrode body in the first direction is M mm, and 0.5<=L-M / 2<=4.5 is satisfied.

5. The cell according to claim 1, wherein The tab structure comprises a bending part and a connecting part, the bending part is arranged between and connected with the electrode body and the connecting part, the connecting part is connected with the pole, at least part of the indentations on the second surface and the weld are located in the connecting part.

6. The cell according to claim 1, wherein The indentations on the first surface have opposite first ends and second ends, the electrode assembly has a second direction intersecting the first direction, the second direction is an extension direction of the tabs, in the second direction, the first ends are located between the second ends and the electrode body, and the weld covers at least part of the first ends.

7. The cell according to claim 1, wherein The indentation on the first face has a plurality of dot-shaped indentations, the electrode assembly has a third direction intersecting the first direction, the third direction is the direction of extension of the weld on the first face, the plurality of dot-shaped indentations are arranged along the third direction and are at least partially covered by the weld.

8. The cell according to claim 1, wherein The indentation on the first face has a plurality of linear indentations, each of the linear indentations extends along a straight line, at least one of the linear indentations intersects the weld or one of the linear indentations coincides with the weld.

9. The cell of claim 1 wherein, The indentation on the first face has at least one planar indentation, the weld covers at least part of the planar indentation, and the planar indentation has one of a polygonal shape, a circular shape, a semicircular shape, and an elliptical shape.

10. A battery pack, characterized by, A single battery comprising the electrode assembly of any one of claims 1-9.

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