Pole piece and secondary battery

Abstract

The embodiment of the utility model provides a pole piece which comprises a current collector comprising a current collector main body and a tab extending from the current collector main body along a first direction; the active material layer is arranged on at least one side of the current collector in the thickness direction, the tab is provided with a tab empty foil area without the active material layer, the pole piece further comprises a reinforcing rib, and in the first direction, the reinforcing rib continuously extends to the surface of the active material layer from the tab empty foil area. The utility model aims to provide a pole piece and a secondary battery so as to at least prevent a lug from being folded.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of pole piece and secondary battery. BACKGROUND

[0002] In the field of new energy power battery, the application of secondary battery is more and more widely, such as secondary battery (for example, lithium ion battery) can be applied to car, energy storage, mobile phone, tablet computer, wearable device, mobile power supply, electronic cigarette, digital product, electric tool, power device, energy storage device and other electronic devices. Secondary battery generally uses copper foil and aluminum foil as its current collector, and after die cutting, the tab is prone to bending, wrinkling and folding. SUMMARY

[0003] In view of the problems in the related art, the utility model aims to provide a kind of pole piece and secondary battery, to at least realize avoiding tab folding.

[0004] To achieve the above object, the embodiment of the present application provides a kind of pole piece, comprising: current collector, including current collector main body and tab that extends from current collector main body in first direction;Active material layer is arranged on at least one side of the current collector in the thickness direction, wherein the tab has tab empty foil area without active material layer, and wherein the pole piece further includes reinforcing rib, reinforcing rib continuously extends from the tab empty foil area to the surface of the active material layer in the first direction.

[0005] In some embodiments, the ratio of the width of the reinforcing rib in the direction perpendicular to its extension path to the depth of the tab recessed on the reinforcing rib is a, 6.67≥a≥1.1.

[0006] In some embodiments, along the first direction, the tab has tab coating area directly connected with the current collector main body and the tab empty foil area directly connected with the tab coating area in sequence, the active material layer is also arranged above the surface of the tab coating area, and the reinforcing rib continuously extends from the tab empty foil area to the part of the active material layer located on the tab coating area.

[0007] In some embodiments, the tab empty foil area is directly connected with the current collector main body, and the reinforcing rib continuously extends from the tab empty foil area to the part of the active material layer located on the current collector main body.

[0008] In some embodiments, along the first direction, the size of the tab coating area is d1, the size of the tab is d3, 0.15≥d1 / d3≥0.02.

[0009] In some embodiments, along the first direction, the size of the tab-coating region is d1, the reinforcing ribs are spaced apart from the portion of the active material layer on the current collector body by a distance d2, and 0.95≥d2 / d1≥0.1.

[0010] In some embodiments, 0.5≥d2 / d1≥0.2.

[0011] In some embodiments, the tab further comprises: an electrically conductive layer covering a surface of the current collector and located between the active material layer and the current collector, the active material layer having a first portion coated on a surface of the electrically conductive layer and a second portion extending beyond the electrically conductive layer along the first direction, the second portion being coated on a surface of the current collector, the reinforcing ribs continuously extending from the tab-foil-free region to the surface of the second portion and continuously extending from the surface of the second portion to the surface of the first portion.

[0012] In some embodiments, a ratio between a depth to which the reinforcing ribs are recessed on the active material layer and a thickness of the active material layer is f, and 0.85≥f≥0.3.

[0013] In some embodiments, a first edge of the tab is connected to the current collector body, and a second edge of the tab is disposed on two sides of the first edge in the first direction; each of the reinforcing ribs has at least one first bend and at least one second bend, the first bend and the second bend are alternately disposed in a tab width direction perpendicular to the first direction and connected by a connecting portion, the tab width direction being perpendicular to the first direction; wherein the first bend and the second bend are circular arc transitions, an inner angle of the first bend faces the first edge, and an inner angle of the second bend faces the second edge; a maximum width of the circular arc transition in a radius direction is y1, a width of the connecting portion perpendicular to an extension direction of the connecting portion is y2, and 2.5≥y1 / y2≥1.2.

[0014] In some embodiments, a distance between two adjacent first bends of a single reinforcing rib is b, wherein, in the tab width direction, the tab has a maximum width c1 and a minimum width c2, and 3≥c1 / b≥1.5 and / or 3≥c1 / b≥1.5.

[0015] The embodiment of the application further provides a secondary battery, comprising: a shell having at least one opening; at least one cover plate assembly comprising a cover plate body and a pole provided on the cover plate body, the cover plate body closing the opening and forming a containing cavity with the shell; an electrode assembly provided in the containing cavity, the electrode assembly comprising the above-mentioned pole piece, the tab blanking area comprising a welding area and a bending area, the welding area being welded with the pole or a transition piece electrically connected with the pole, and the bending area being located between the welding area and the current collector body; wherein, along the height direction of the secondary battery, the bending area is spaced apart from the active material layer.

[0016] In some embodiments, along the height direction of the secondary battery, the spacing distance between the bending area and the active material layer is d4, and 10mm>=d4>=4mm.

[0017] The beneficial technical effects of the utility model lie in:

[0018] The embodiment of the application forms a continuous reinforcing rib between the tab blanking area and the active material layer, so that the tab blanking area and the active material layer are connected into a whole under the action of the reinforcing rib, and a weak part is avoided to be formed at the junction of the tab blanking area and the active material layer, so that the tab is prevented from being folded at the weak part. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A schematic view after forming the reinforcing rib on the pole piece according to the first embodiment of the application is shown.

[0021] Figure 2 A schematic view after the die-cutting process of the pole piece according to the first embodiment of the application is shown.

[0022] Figure 3 A schematic view after forming the reinforcing rib on the pole piece according to the second embodiment of the application is shown.

[0023] Figure 4 A schematic view after the die-cutting process of the pole piece according to the second embodiment of the application is shown.

[0024] Figure 5 A schematic view after forming the reinforcing rib on the pole piece according to the second embodiment of the application is shown. Figure 4 An enlarged view of the A area in FIG. 8.

[0025] Figure 6 A cross-sectional view taken along Figure 4 line B-B of FIG. 1 is shown.

[0026] Figure 7 A schematic view showing the formation of the reinforcing rib on the pole piece according to the third embodiment of the present application is shown.

[0027] Figure 8 A schematic view showing the pole piece after the die-cutting process according to the third embodiment of the present application is shown.

[0028] Figure 9 A schematic view showing the pole tab in Figure 5 is shown.

[0029] Figure 10 A partial enlarged schematic view showing a portion of one of the fold line portions in Figure 9 is shown.

[0030] Figure 11 A schematic view showing the pole tab according to another embodiment of the present application is shown.

[0031] Figure 12 A schematic view showing a different embodiment from Figure 11 is shown.

[0032] Figure 13 A perspective view showing a secondary battery according to an embodiment of the present application is shown.

[0033] Figure 14 A perspective view showing a portion of an electrode assembly according to an embodiment of the present application is shown.

[0034] Figure 15 A cross-sectional view showing a secondary battery according to an embodiment of the present application is shown.

[0035] Figure 16 A schematic view showing the electronic device as a vehicle according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] For better understanding of the spirit of the embodiments of the present application, the same will be further described in conjunction with some preferred embodiments of the present application.

[0037] The embodiments of the present application will be described in detail in the following. In the entire description of the present application, the same or similar components and components having the same or similar functions are denoted by similar reference numerals. The embodiments described herein with respect to the accompanying drawings are of illustrative nature, diagrammatic nature and for providing a basic understanding of the present application. The embodiments of the present application should not be interpreted as a limitation of the present application.

[0038] As used herein, the terms "approximately," "about," "substantially" and "near" are used to describe and account for small variations. When used in connection with a event or circumstance, the terms can refer to instances in which the event or circumstance is the same, but can also refer to instances in which the event or circumstance is nearly the same.

[0039] In this description, relative terms such as "central," "longitudinal," "lateral," "forward," "rearward," "rightward," "leftward," "internal," "external," "lower," "higher," "horizontal," "vertical," "above," "below," "top," "bottom," and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the application be practiced with any particular orientation.

[0040] For convenience, "first," "second," "third," etc. can be used herein to describe different components of one or more figures. The first, second, third, etc. are not intended to denote a corresponding component.

[0041] After the die-cutting process, the pole piece needs to be wound into a large roll first. During the winding process, due to the softness of the tab, it is likely that the tab will be folded and inserted into the core and overlap with the pole piece body. The folded tab will subsequently enter the battery during the subsequent processing process, which will cause the internal resistance to increase. More seriously, the folded tab inserted into the core may cause a short circuit between the positive and negative electrodes, affecting the safety performance of the battery.

[0042] Figure 1 A schematic view showing the pole piece 100 after forming the reinforcing ribs 30 according to the first embodiment of the present application is shown. Figure 2 A schematic view showing the pole piece 100 after the die-cutting process according to the first embodiment of the present application is shown, in which the die-cutting is performed along the dashed line C in Figure 1 Figure 3 A schematic view showing the pole piece 100 after forming the reinforcing ribs 30 according to the second embodiment of the present application is shown. Figure 4 A schematic view showing the pole piece 100 after the die-cutting process according to the second embodiment of the present application is shown, in which the die-cutting is performed along the dashed line D in Figure 3 Figure 5 A schematic view showing the A area in Figure 4 Figure 6 A schematic view showing the B-B line in Figure 4 Figure 7 A schematic view showing the pole piece 100 after forming the reinforcing ribs 30 according to the third embodiment of the present application is shown. Figure 8 ​​​​A schematic view of the pole piece 100 according to the third embodiment of the present application after the die-cutting process is shown, in which the die-cutting is performed along the dashed line E in Figure 7 .

[0043] The first to third embodiments of the present application provide a pole piece 100, the pole piece 100 comprising a current collector 10 and active material layers 20, the active material layers 20 being disposed on both sides of the current collector 10 in the thickness direction, the current collector 10 comprising a current collector body 12 and a tab 14 extending out of the current collector body 12 in a first direction d; the active material layers 20 are at least coated on the surface of the current collector body 12. The tab 14 has a tab empty foil area 40 where no active material layer 20 is disposed, and in the first direction d, a reinforcing rib (also referred to as an embossing) 30 continuously extends from the tab empty foil area 40 to the surface of the active material layer 20 of one of the two active material layers 20 in the thickness direction of the current collector 10 to support the tab 14. The embodiments of the present application form a continuous reinforcing rib 30 between the tab empty foil area 40 and the active material layer 20, so that the tab empty foil area 40 and the active material layer 20 are joined together under the action of the reinforcing rib 30, avoiding the formation of a weak part at the junction of the tab empty foil area 40 and the active material layer 20, and causing the tab 14 to be folded at the weak part. At the same time, the root of the tab 14 is supported by the active material layer 20, and the tab empty foil area 40 and the active material layer 20 are joined together under the action of the reinforcing rib 30, improving the bending resistance of the tab 14 as a whole.

[0044] In some embodiments not shown in the figures, the active material layer 20 is disposed on one of the surfaces of the current collector 10 in the thickness direction, and the reinforcing rib 30 continuously extends from the tab empty foil area 40 to the active material layer 20.

[0045] The ratio of the width of the reinforcing rib 30 in the direction perpendicular to its extension path to the depth of the recess on the tab 14 is a, and 6.67≥a≥1.1. If a is greater than 6.67, the depth of the recess of the reinforcing rib 30 on the tab 14 is too small to ensure the reinforcing effect on the tab 14. If a is less than 1.1, the width of the reinforcing rib 30 is too small, which has the risk of crushing the tab 14.

[0046] In the first to third embodiments, the pole piece 100 can be a negative pole piece, and the current collector 10 is, for example, a copper foil, for example, see the enlarged view of the second embodiment Figure 5 , in which the reinforcing rib 30 continuously extends from the tab empty foil area 40 to the surface of the active material layer 20.

[0047] Referring to Figure 1 and Figure 2The first embodiment of the present application improves the prior art stripe-shaped reinforcing rib. Compared with the prior art (the reinforcing rib is only located in the tab empty foil area), the reinforcing rib 30 of the first embodiment of the present application continuously extends from the tab empty foil area 40 to the surface of the active material layer 20. First, the area where the active material layer 20 is located not only includes the current collector (foil) 10, but also the active material layer 20 on the surface thereof, and thus has a larger thickness and is less likely to be bent, so that the strength of the active material layer 20 can be relied on to reinforce the tab 14 as a whole, avoiding the formation of a weak part between the reinforcing rib 30 and the active material layer 20, and causing the tab 14 to be folded from the weak part. Second, the reinforcing effect of the tab 14 can be increased by connecting the reinforcing areas of the plurality of stripe-shaped reinforcing ribs 30 into a whole body by relying on the reinforcing effect of the active material layer 20.

[0048] In the second to third embodiments, for example, see the enlarged view of the second embodiment Figure 5 The difference from the first embodiment includes that the reinforcing rib 30 is W-shaped, which can utilize the stability of the triangle on the one hand, and the reinforcing rib 30 in the W shape is connected into a whole body, and the reinforcing effect on the tab 14 is better than that of the stripe-shaped reinforcing rib 30 of the first embodiment.

[0049] In the first and second embodiments, for example, see the enlarged view of the second embodiment Figure 5, along the first direction d, the tab 14 has, in sequence, a tab-coated region 42 directly connected to the current collector body 12, and a tab-foil-free region 40 directly connected to the tab-coated region 42, the active material layer 20 is disposed above the current collector body 12, the active material layer 20 is also disposed above the surface of the tab-coated region 42, and the reinforcing rib 30 continuously extends from the tab-foil-free region 40 to the surface of the portion of the active material layer 20 located on the tab-coated region 42. The active material layer 20 is disposed on the tab-coated region 42 of the tab 14, compared to the embodiment in which the tab 14 is entirely the tab-foil-free region 40, the active material layer 20 can provide reinforcement to the root of the tab 14, preventing the tab 14 from being folded as a whole. Along the first direction d, the size of the tab-coated region 42 (i.e. the height of the active material layer 20 located on the tab 14) is d1, and the size of the tab 14 (i.e. the height of the tab 14) is d3, 0.15≥d1 / d3≥0.02. If d1 / d3 is too large, such as greater than 0.15, on the one hand, it will lead to waste of the active material layer 20; on the other hand, it will lead to a decrease in the size of the tab-foil-free region 40 of the tab 14, and further lead to a decrease in the size of the welding region 400 available for welding and a decrease in the welding process window. If d1 / d3 is too small, such as less than 0.02, the reinforcement effect of the active material layer 20 on the tab 14 is too weak. When d1 / d3 is in a reasonable range, the size of the welding region 400 available for welding can be ensured, and at the same time, a large enough d1 can be provided, and further the reinforcing rib 30 can occupy a large enough size on the tab-coated region 42, so that the ability of the tab 14 as a whole to prevent folding is guaranteed.

[0050] Continuing to refer to Figure 5 Further, along the first direction d, the reinforcing rib 30 is spaced apart from the portion of the active material layer 20 located on the current collector body 12, and the spacing distance is d2, d1 and d2 satisfy 0.95≥d2 / d1≥0.1. That is, the reinforcing rib 30 is spaced apart from the main body of the negative electrode tab, if the proportion of d2 in d1 is too large, i.e. d2 / d1 is too large, such as greater than 0.95, it will lead to insufficient joint area of the reinforcing rib 30 on the tab-coated region 42, and insufficient reinforcement effect on the tab 14; if the proportion of d2 in d1 is too small, i.e. d2 / d1 is too small, such as less than 0.1, the reinforcing rib 30 may enter the reaction film region of the main body of the negative electrode tab due to processing errors, along the stacking direction of the tab 100, the reinforcing rib 30 is likely to overlap with the projection of the active material layer of the positive electrode tab, thereby causing problems such as edge lithium precipitation. Preferably, 0.5≥d2 / d1≥0.2.

[0051] In some embodiments, the active material layer 20 is directly coated on the surface of the current collector 10, in other embodiments, referring to Figure 6The conductive layer 50 is provided on the surface of the current collector 10, and the active material layer 20 has a first portion 21 coated on the surface of the conductive layer 50, and a second portion 22 extending beyond the conductive layer 50 in the first direction d and coated on the surface of the current collector 10. The reinforcing rib 30 continuously extends from the tab blanking area 40 to the surface of the second portion 22, and continuously extends from the surface of the second portion 22 to the surface of the first portion 21. The second portion 22 of the active material layer 20 is thin, and if the reinforcing rib 30 only extends to the second portion 22, the second portion 22 is easy to fall off. The reinforcing rib 30 extends to the surface of the first portion 21, i.e. to the surface of the active material layer 20 on the conductive layer 50, and the conductive layer 50 has certain support to the whole active material layer 20, and the active material layer 20 is prevented from falling off in the process of forming the reinforcing rib 30 by the conductive layer 50.

[0052] In Figure 7 to Figure 8 In the third embodiment shown in the figure, the tab blanking area 40 is directly connected to the current collector body 12, and the reinforcing rib 30 continuously extends from the tab blanking area 40 to the surface of the portion of the active material layer 20 on the current collector body 12. Compared with the first and second embodiments, the active material layer 20 is not cut off in the die-cutting step, and the waste of the active material layer 20 is reduced, and the cost is saved.

[0053] In some embodiments, the ratio between the depth of the recess of the reinforcing rib 30 in the active material layer 20 and the thickness of the active material layer is f, 0.85≥f≥0.3, that is, the ratio between the depth of the reinforcing rib 30 and the thickness of the portion of the active material layer 20 where the reinforcing rib 30 is located is 30%-85%. That is, in the cross-sectional view of the reinforcing rib 30 and the active material layer 20 taken along the direction perpendicular to the first direction d and parallel to the thickness direction, the ratio between the depth of the reinforcing rib 30 and the thickness of the active material layer 20 in the cross-sectional view is 30%-85%. If the ratio is too small, the reinforcing rib 30 is insufficient for the tab 14, and if the ratio is too large, the active material in the active material layer 20 is easy to fall off.

[0054] It should be noted that: please refer to Figure 6 If the active material layer 20 is provided with a thinning area near the edge of the tab, the ratio between the depth of the recess of the reinforcing rib 30 in the active material layer 20 and the thickness of the active material layer 20 at each position of the reinforcing rib 30 satisfies 30%-85%.

[0055] Figure 9 It is shown that Figure 5In some embodiments, the reinforcing rib 30 is in a zigzag shape. The zigzag reinforcing rib 30 can pass through the tab 150 along the tab width direction w (perpendicular to the first direction d). The zigzag reinforcing rib 30 has a plurality of first bending portions 1961 and second bending portions 1962, at which the reinforcing rib 30 is bent. It should be understood that the zigzag shape refers to a zigzag line composed of end portions of a plurality of connecting portions (which can extend along a straight line, such as the first connecting portion 192 and the second connecting portion 194 described below, or can take other forms, such as an arc) sequentially connected by bending portions (such as the first bending portion 1961 and the second bending portion 1962). The bending portion can be any suitable structure capable of functioning as an angle bending portion to change the extension direction of the zigzag line, which is not limited in the present application, for example, the bending portion can have a rounded corner. In some embodiments, the bending angle of each first bending portion 1961 and second bending portion 1962 is A1. The bending angle A1 is in the range of 28°-45°.

[0056] Since the triangle has good stability, the zigzag reinforcing rib 30, which is a stable structure similar to a triangle, can provide good reinforcement effect for the tab. However, if the bending angle A1 of the zigzag reinforcing rib 30 is too small, the distance along the tab width direction w in the bending angle A1 region will be too small, which will cause stress concentration in the tab 14 in the bending angle A1 region and eventually lead to tab 14 cracking and other conditions. On the other hand, after the distance is too small, the effect of the reinforcing rib 30 on both sides of the bending angle A1 approaches that of a single stripe-shaped reinforcing rib, which reduces the stability effect of the triangle. If the bending angle A1 is too large, the corresponding tab region in the bending angle A1 region becomes wide, and at this time, the reinforcing rib on both sides of the bending angle A1 is insufficient to effectively reinforce the tab region therebetween, which is prone to fold downward to the main body region of the tab.

[0057] Therefore, the inventors have found through experimental verification and research that by configuring the bending angle A1 in the range of 28°-45°, the tab 14 can be more effectively reinforced, and tab 14 cracking can be effectively avoided. Preferably, the angle A1 is in the range of 30°-35°. The value range of the angle A1 can further provide more effective reinforcement for the tab 14 and effectively avoid tab 14 cracking.

[0058] The first edge of the tab 14 is connected with the current collector body 12, and the second edge of the tab 14 is arranged on both sides of the first edge in the first direction d; each of the reinforcing ribs 30 has at least one first bending portion 1961 and at least one second bending portion 1962, the first bending portion 1961 and the second bending portion 1962 are arranged alternately in the tab width direction w and connected by a connecting portion, and the tab width direction w is perpendicular to the first direction d; wherein the first bending portion 1961 and the second bending portion 1962 are circular arc transitions, the inner angle of the first bending portion 1961 faces the first edge, and the inner angle of the second bending portion 1962 faces the second edge, that is, the first bending portion 1961 and the second bending portion 1962 of the reinforcing rib 30 respectively protrude towards the first direction d1 and the opposite direction of the first direction d1. In this way, the reinforcing rib 30 can provide more effective reinforcement effect on the tab 14 in the first direction d, and at the same time effectively avoid the tab 14 from being crushed.

[0059] The maximum width of the first bending portion 1961 and the second bending portion 1962 in the radius direction of the circular arc transition is y1 (y1 is, for example, the size of the portion of the axis Lx on the first bending portion 1961), the width of the connecting portion perpendicular to the extension direction thereof is y2, and 2.5≥y1 / y2≥1.2. The reinforcing rib involved in the present application can be processed by rolling or stamping, for example, the tab and the active material layer are rolled by using an embossing roller. When the ratio of y1 / y2 is lower than the lower limit value 1.2, it is difficult to form a smooth chamfer of the circular arc transition, for example, the tab 30 is easily damaged when the reinforcing rib 30 is rolled. If the ratio is higher than the upper limit value 2.5, wrinkles are easily generated in the area between adjacent connecting portions (for example, the first connecting portion 192 and the second connecting portion 194) during the rolling process, which is not conducive to the subsequent welding of the tab 30.

[0060] Specifically, the fold line-shaped reinforcing rib 30 can include at least one fold line portion 190G, and the plurality of fold line portions 190G are sequentially adjacent in the tab width direction w. Figure 10 A local enlarged schematic view of a part of one fold line portion 190G in Figure 9 In fact, Figure 9 Each fold line portion 190G outlined by a dashed box in Figure 10 A complete second bending portion 1962 is shown for ease of understanding.

[0061] Referring to Figure 9 and Figure 10Each of the fold line portions 190G can include a first connecting portion 192 and a second connecting portion 194. The first connecting portion 192 extends longitudinally from one end 192a thereof to another end 192b thereof. The second connecting portion 194 extends longitudinally from one end 194a thereof to another end 194b thereof. The one end 192a of the first connecting portion 192 is connected with the one end 194a of the second connecting portion 194. The other end 194b of the second connecting portion 194 of each of the fold line portions 190G is connected with the other end 192b of the first connecting portion 192 of the adjacent other fold line portion 190G. The first connecting portion 192 and the second connecting portion 194 are arranged at an angle A1. The angle A1 can be an angle defined between the inner sides 1921, 1941 of the first connecting portion 192 and the second connecting portion 194 opposite to each other. That is, the first connecting portion 192 and the second connecting portion 194 are arranged at the bending angle A1.

[0062] More specifically, the one end 192a of the first connecting portion 192 and the one end 194a of the second connecting portion 194 can be connected with each other by a first bending portion 1961. The inner sides of the first bending portion 1961 and the second bending portion 1962 are arranged as an inner fillet An with a radius Rn and a corresponding center O1. The inner sides 1921, 1941 of the first connecting portion 192 and the second connecting portion 194 opposite to each other are connected by the inner fillet An. In some embodiments, the radius Rn of the inner fillet An is not less than 0.5 mm. For the corresponding angle A1 in the range of 28°-45°, the vertex angle (at the first bending portion 1961 and the second bending portion 1962) is prone to be a stress concentration area. By arranging the inner sides of the first bending portion 1961 and the second bending portion 1962 as the inner fillet An and controlling the radius Rn of the inner fillet An to be not less than 0.5 mm, the stress concentration problem of the inner sides of the first bending portion 1961 and the second bending portion 1962 can be effectively alleviated.

[0063] In addition, the outer sides of the first bending portion 1961 and the second bending portion 1962 are arranged as an outer fillet Ao with a radius Ro and a corresponding center O2. The back sides 1922, 1942 of the first connecting portion 192 and the second connecting portion 194 away from each other are connected by the outer fillet Ao. In some embodiments, the radius Ro of the outer fillet Ao is not less than 1.5 mm. As described above, for the corresponding angle A1 in the range of 28°-45°, the vertex angle (at the first bending portion 1961 and the second bending portion 1962) is prone to be a stress concentration area. By arranging the outer sides of the first bending portion 1961 and the second bending portion 1962 as the outer fillet Ao and controlling the radius Ro of the outer fillet Ao to be not less than 1.5 mm, the stress concentration problem of the outer sides of the first bending portion 1961 and the second bending portion 1962 can be effectively alleviated.

[0064] Each folded portion 190G may also include an axis Lx passing through the centers O1 and O2. The axis Lx may be perpendicular to the tab width direction w. The first connecting portion 192 and the second connecting portion 194 may be symmetrical with respect to the axis Lx, and the first bent portion 1961 may also be symmetrical with respect to the axis Lx. The angle between the first connecting portion 192 or the second connecting portion 194 and the axis Lx is half of angle A1. For example, Figure 10 As shown, the angle A2 between the inner side 1941 of the second connecting part 194 and the axis Lx is 1 / 2 of the angle A1.

[0065] Figure 11 A schematic diagram of a tab 14 according to another embodiment of this application is shown. The tab 14 is provided with a reinforcing rib array, which includes a plurality of reinforcing ribs 30 arranged along a first direction d, with each adjacent pair of reinforcing ribs 30 spaced apart from each other, and at least one reinforcing rib 30 extending continuously from the tab empty foil region 40 to the surface of the active material layer. Each reinforcing rib 30 can be coupled with… Figure 9 to Figure 10 The reinforcing ribs 30 shown are the same or similar. By setting an array of reinforcing ribs on the tab 14 and spacing adjacent reinforcing ribs 30 apart along the first direction d, as many reinforcing ribs 30 as possible are used to cover the surface of the tab 14, forming a dense array of reinforcing ribs to achieve a stronger support effect for the tab 14.

[0066] In some embodiments, the distance between the vertices of two adjacent first bends 1961 of a single reinforcing rib 30 is b. In the tab width direction w, the tab 14 has a maximum width c1 and a minimum width c2. The ratio of c1 to b is in the range of 1.5-3, where 3 ≥ c1 / b ≥ 1.5, and / or the ratio of c2 to b is in the range of 1.5-3, where 3 ≥ c1 / b ≥ 1.5. When this ratio is greater than 1.5, it is possible to ensure that a reinforcing rib array with at least one W-shaped reinforcing rib 30 is formed on the tab 14 after rolling to ensure the reinforcing effect. However, if this ratio is too large, for example, greater than 3, the reinforcing rib array formed at this time is too dense and is prone to damaging the tab 14.

[0067] Figure 12 It shows the relationship with Figure 11 Different implementations, in Figure 11 In the illustrated embodiment, a single continuous reinforcing rib 30 extends continuously from one edge of the electrode 14 to the other without interruption in the width direction w of the electrode tab. Figure 12 In the illustrated embodiment, along the first direction d, a discontinuous reinforcing rib (also referred to as a truncated reinforcing rib) 30' is further provided between the upper and lower edges of the continuous reinforcing rib 30 and the tab 14 (not extending continuously from one edge of the tab 14 to the other along the tab width direction w). Compared to Figure 11In the shown embodiment, the stress concentration at the second bending portion 1962 of the lower end of the continuous reinforcing rib 30 is alleviated by providing the discontinuous reinforcing rib 30', and the active material layer 20 is prevented from being peeled off due to stress concentration during the rolling process.

[0068] Figure 13 A perspective view of a secondary battery 1300 according to an embodiment of the present application is shown. Figure 14 A perspective view of a partial electrode assembly 500 according to an embodiment of the present application is shown, Figure 15 A cross-sectional view of a secondary battery 1300 according to an embodiment of the present application is shown. The secondary battery 1300 is, for example, a prismatic battery, and the secondary battery 1300 can also be a cylindrical or pouch battery. The secondary battery 1300 includes a housing 600, a cover plate assembly 602, and an electrode assembly 500. The housing 600 has an opening, and the cover plate assembly 602 includes a cover plate body 613, polarity-opposed pole posts 611, 612 disposed on the cover plate body 613 (optionally, further including two adapter tabs respectively electrically connecting the pole posts 611, 612), wherein the cross-sectional view Figure 15 Only the pole post 612 and the corresponding adapter tab 618 are shown, and the cover plate body 613 closes the opening and forms a containing cavity with the housing 600. The electrode assembly 500 is disposed in the containing cavity, and the electrode assembly 500 includes any of the first to third embodiments of the negative electrode tab. The electrode assembly 500 can include the negative electrode tab, the separator, and the positive electrode tab stacked in sequence. The electrolyte can be located between the negative electrode tab, the separator, and the positive electrode tab.

[0069] It should be noted that the present application is exemplified by the housing 600 having one opening. In other embodiments not shown in the figures, the housing 600 has multiple openings, for example, two openings can be disposed at the two ends along the height direction h, and each opening is closed by a cover plate assembly 602. The positive electrode tabs and the negative electrode tabs are drawn out of the electrode assembly 500 in opposite directions.

[0070] Referring to Figure 14 , the electrode assembly 500 is, for example, a jelly-roll, and the electrode assembly 500 can also be a stack. The plurality of positive electrode tabs are bundled and fixed together, for example, by welding. The plurality of negative electrode tabs are bundled and fixed together, for example, by welding. Referring to Figure 15 , the secondary battery 1300 includes, for example, two electrode assemblies 500, and the electrode tabs 14 can be drawn out of the entire thickness of the electrode assembly 500 as shown in Figure 14 , or the electrode tabs 14 can be drawn out of half the thickness of the electrode assembly as shown in Figure 15 .

[0071] For reference Figure 15 and Figure 5The tab foil area 40 includes a welding area 400 that is welded to the adapter piece 618 (or directly welded to the terminal post 612 without the adapter piece 618), and a bending area 402 located between the welding area 402 and the current collector body 12. Along the height direction h of the secondary battery 1300, the bending area 402 is spaced from the active material layer to prevent the active material layer from falling off from the current collector 10 due to bending stress. Specifically, when the secondary battery 1300 is in the installed state, the distance between the bending area 402 and the active material layer along the height direction h is d4, where 10mm ≥ d4 ≥ 4mm. If d4 is too small, the distance between the bending area 402 and the edge of the active material layer is too close. The stress generated during the bending of the tab 14 is easily transmitted to the coating edge of the active material layer through the reinforcing rib 30, causing the edge of the active material layer to peel off. If d4 is too large, the distance between the bending area 402 and the edge of the active material layer is too far, resulting in the tab 14 occupying too much height space in the secondary battery 1300, causing wasted space. The height direction h typically points from the electrode assembly 500 to the cover assembly 602.

[0072] This utility model also provides an electronic device 1000. For ease of explanation, the following embodiments will use a vehicle as an example to illustrate the electronic device 1000. Figure 16 This illustration shows an electronic device 1000 in an embodiment of this application when it is a vehicle. A battery pack 1002 is installed inside the vehicle, and the battery pack 1002 can be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The battery pack 1002 provides electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part is a unit component that can obtain electrical power from the battery pack 1002 and perform corresponding tasks, such as a fan blade rotation unit or a vacuum cleaner's suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0073] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electrode sheet, characterized in that, include: The current collector includes a current collector body and an electrode extending from the current collector body along a first direction; An active material layer is disposed on at least one side of the current collector in the thickness direction. The electrode tab has an empty foil area without an active material layer, and the electrode sheet further includes reinforcing ribs that extend continuously from the empty foil area to the surface of the active material layer in the first direction.

2. The electrode sheet according to claim 1, characterized in that, The ratio of the width of the reinforcing rib in the direction perpendicular to its extension path to the depth of the reinforcing rib recessed on the electrode lug is a, and 6.67≥a≥1.

1.

3. The electrode sheet according to claim 1, characterized in that, Along the first direction, the electrode tab sequentially has an electrode tab coating area directly connected to the current collector body, and an electrode tab empty foil area directly connected to the electrode tab coating area. The active material layer is also disposed above the surface of the electrode tab coating area. The reinforcing rib extends continuously from the tab foil area to the portion of the active material layer located on the tab coating area.

4. The electrode sheet according to claim 1, characterized in that, The electrode foil area is directly connected to the current collector body, and The reinforcing rib extends continuously from the tab foil area to the portion of the active material layer located on the current collector body.

5. The electrode sheet according to claim 3, characterized in that, Along the first direction, the size of the tab coating area is d1, the size of the tab is d3, and 0.15≥d1 / d3≥0.

02.

6. The electrode sheet according to claim 3, characterized in that, Along the first direction, the size of the electrode coating area is d1, the reinforcing rib and the portion of the active material layer located on the current collector body are spaced apart, and the spacing distance is d2, 0.95≥d2 / d1≥0.

1.

7. The electrode sheet according to claim 6, characterized in that, 0.5≥d2 / d1≥0.

2.

8. The electrode sheet according to claim 3, characterized in that, Also includes: A conductive layer covers the surface of the current collector and is located between the active material layer and the current collector. The active material layer has a first portion coated on the surface of the conductive layer and a second portion extending beyond the conductive layer along the first direction. The second portion is coated on the surface of the current collector. The reinforcing rib extends continuously from the tab foil region to the surface of the second portion and from the surface of the second portion to the surface of the first portion.

9. The electrode sheet according to claim 1, characterized in that, The ratio between the depth of the reinforcing rib recessed on the active material layer and the thickness of the active material layer is f, where 0.85 ≥ f ≥ 0.

3.

10. The electrode sheet according to claim 1, characterized in that, The first edge of the electrode tab is connected to the current collector body, and the second edge of the electrode tab and the first edge are disposed on both sides of the electrode tab in the first direction; Each of the reinforcing ribs has at least one first bend and at least one second bend, the first bend and the second bend are alternately arranged in the tab width direction and connected by a connecting part, the tab width direction is perpendicular to the first direction; Wherein, the first bend and the second bend are circular arc transitions, the inner angle of the first bend faces the first edge, and the inner angle of the second bend faces the second edge; the maximum width of the circular arc transition in the radial direction is y1, and the width of the connecting part perpendicular to the extension direction of the connecting part is y2, 2.5≥y1 / y2≥1.

2.

11. The electrode according to claim 10, characterized in that, The distance between the vertices of two adjacent first bends of a single reinforcing rib is b. Wherein, in the direction of the tab width, the tab has a maximum width c1 and a minimum width c2, wherein: 3≥c1 / b≥1.5, and / or, 3≥c1 / b≥1.

5.

12. A secondary battery, characterized in that, include: The housing has at least one opening; At least one cover plate assembly includes a cover plate body and a pole post disposed on the cover plate body, wherein the cover plate body closes the opening and forms a receiving cavity with the housing; An electrode assembly is disposed within the receiving cavity, the electrode assembly comprising an electrode sheet as described in any one of claims 1-11, the electrode tab empty foil area comprising a welding area and a bending area, the welding area being welded to the electrode post or to an adapter piece electrically connected to the electrode post, the bending area being located between the welding area and the current collector body; wherein... Along the height direction of the secondary battery, there is a gap between the bending region and the active material layer.

13. The secondary battery according to claim 12, characterized in that, Along the height direction of the secondary battery, the distance between the bending area and the active material layer is d4, where 10mm ≥ d4 ≥ 4mm.

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