Pole piece, secondary battery and electronic device

Abstract

The embodiment of the utility model provides a pole piece, a secondary battery and an electronic device, the pole piece comprises a pole piece main body, the pole piece main body comprises a current collector and active material layers, the current collector is provided with two opposite surfaces along the thickness direction of the current collector, and the two surfaces are respectively coated with the active material layers; the tab extends out of the pole piece main body along the first direction, the tab is provided with a second reinforcing rib area and a first reinforcing rib area along the first direction, the second reinforcing rib area is arranged between the first reinforcing rib area and the active substance layer, reinforcing ribs are arranged in the first reinforcing rib area and the second reinforcing rib area, and the first reinforcing rib area and the second reinforcing rib area are arranged along the first direction. The depth of the reinforcing ribs in the first reinforcing rib area is larger than that of the reinforcing ribs in the second reinforcing rib area. According to the technical scheme provided by the invention, the possibility that the tab is bent is reduced, and meanwhile, the active substance of the pole piece can be prevented from falling off.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly to a tab, a secondary battery and an electronic device. BACKGROUND

[0002] For secondary batteries in the field of new energy power batteries, copper foil and aluminum foil are generally used as current collectors of tabs. With the thinning of the foil, the bending resistance of the foil itself is extremely low, and the tab ears are prone to folding and even tearing, which greatly affects the production efficiency and yield of the battery.

[0003] The existing technology improves the bending strength of the tab ear by setting a reinforcing rib on the surface of the tab ear. Compared with the tab ear without the reinforcing rib, the strength of the tab ear can be improved, and the possibility of tab ear bending can be reduced. However, the existing reinforcing rib structure still has some deficiencies. CONTENT OF THE UTILITY MODEL

[0004] In view of the problems in the related art, the purpose of the present application is to provide a tab, a secondary battery and an electronic device, which can reduce the possibility of tab ear bending while avoiding the active material of the tab from falling off.

[0005] To achieve the above-mentioned purpose, an embodiment of the present application provides a tab, which comprises: a tab body comprising a current collector and an active material layer, the current collector having two surfaces opposite along the thickness direction of the current collector, and the two surfaces are respectively coated with the active material layer; and a tab ear extending from the tab body along a first direction, the tab ear being provided with a second reinforcing rib area and a first reinforcing rib area along the first direction, wherein along the first direction, the second reinforcing rib area is arranged between the first reinforcing rib area and the active material layer, and the first reinforcing rib area and the second reinforcing rib area are provided with reinforcing ribs, wherein the depth of the reinforcing ribs in the first reinforcing rib area is greater than the depth of the reinforcing ribs in the second reinforcing rib area.

[0006] In some embodiments, the tab ear comprises a tab ear blank area and a tab ear coating area, the tab ear coating area being connected between the tab ear blank area and the tab body, the active material layer is also coated on the tab ear coating area, the tab ear is further provided with a third reinforcing rib area, the third reinforcing rib area is located at the surface of the active material layer in the tab ear coating area and the part adjacent to the junction, the reinforcing ribs in the third reinforcing rib area and the reinforcing ribs in the second reinforcing rib area form a continuous reinforcing rib, and the depth of the reinforcing ribs in the third reinforcing rib area is greater than the depth of the reinforcing ribs in the second reinforcing rib area.

[0007] In some embodiments, the ratio between the depth of the reinforcing ribs in the third reinforcing rib area and the thickness of the active material layer where the reinforcing ribs are located is 30%-85%.

[0008] In some embodiments, the reinforcing ribs in the first reinforcing rib region, the reinforcing ribs in the second reinforcing rib region and the reinforcing ribs in the third reinforcing rib region form at least one continuous reinforcing rib; or, the reinforcing ribs in the first reinforcing rib region and the reinforcing ribs in the second reinforcing rib region form at least one continuous reinforcing rib.

[0009] In some embodiments, the ratio of the width of the at least one continuous reinforcing rib to the corresponding depth thereof is a, and 1.1≤a≤6.67.

[0010] In some embodiments, the tab is connected to a first edge of the tab body, the first edge extends along a second direction perpendicular to the first direction, the reinforcing ribs in the third reinforcing rib region have end portions in the opposite direction of the first direction, and the end portions have a gap between the first edge in the opposite direction of the first direction.

[0011] In some embodiments, the reinforcing ribs in the third reinforcing rib region include two reinforcing ribs arranged at an angle, and the two reinforcing ribs are connected to each other to form a V-shaped structure.

[0012] In some embodiments, the tab further includes a conductive layer, a portion of the conductive layer is located between the active material layer and the current collector of the tab body, another portion of the conductive layer extends to the third reinforcing rib region along the first direction, and the active material layer in the tab coating area covers the other portion of the conductive layer, wherein the reinforcing ribs in the third reinforcing rib region have end portions in the opposite direction of the first direction, and the end portions overlap the conductive layer in the thickness direction of the tab.

[0013] In some embodiments, the tab is connected to a first edge of the tab body, and a second edge of the tab is arranged on both sides of the tab in the first direction from the first edge; each continuous reinforcing rib has at least one first transition portion and at least one second transition portion, the first transition portion and the second transition portion are arranged alternately in the tab width direction perpendicular to the first direction and are connected by a connecting portion; wherein the first transition portion and the second transition portion are circular arc transition regions, the inner angle of the first transition portion faces the first edge, and the inner angle of the second transition portion faces the second edge; the maximum width of the circular arc transition region is y1, the width of the connecting portion perpendicular to the extension direction of the connecting portion is y2, and 1.2≤y1 / y2≤2.5.

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

[0015] The embodiments of the present application also provide a secondary battery, comprising an electrode assembly, the electrode assembly comprising a positive electrode tab, a negative electrode tab, and a separator between the positive electrode tab and the negative electrode tab, wherein at least one of the positive electrode tab and the negative electrode tab is the tab of any one of the above.

[0016] In some embodiments, the negative electrode tab of the secondary battery is the tab of any one of the above.

[0017] The embodiments of the present application also provide an electronic device comprising the secondary battery of any one of the above.

[0018] The beneficial technical effects of the present application are that:

[0019] The technical solution of the present application sets the depth of the reinforcing ribs in the second reinforcing rib area of the tab to be less than the depth of the reinforcing ribs in the first reinforcing rib area, which can avoid the reinforcing ribs near the root of the tab from falling off the active material around them due to excessive stress caused by the large depth during the forming process. In addition, by setting the depth of the reinforcing ribs in the second reinforcing rib area to be shallower than the depth of the reinforcing ribs in the first reinforcing rib area and the third reinforcing rib area, the depth of the reinforcing ribs is configured to change from the first reinforcing rib area to the third reinforcing rib area, and the second reinforcing rib area with a smaller depth is used to transition between the first reinforcing rib area and the third reinforcing rib area, which can make the tab easier to bend in the subsequent bending process, reduce the possibility of the tab tearing, and avoid the stress generated by bending from being transmitted to the interface of the tab coating area to cause the active material to fall off. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0021] Figures 1A-1F is a schematic diagram showing different manufacturing stages of manufacturing a tab according to an embodiment of the present application.

[0022] Figure 2 is Figure 1F is a partial enlarged view of the area A1 of the tab shown.

[0023] Figure 3A and Figure 3B are cross-sectional schematic diagrams of the first reinforcing rib area and the second reinforcing rib area of the tab according to the present application, respectively.

[0024] Figure 3CThis is a cross-sectional schematic diagram of the third reinforcing rib region of the electrode lug according to this application.

[0025] Figure 3D This is a schematic diagram of a continuous reinforcing rib according to an embodiment of this application.

[0026] Figure 4 A schematic cross-sectional view of an electrode according to some other embodiments is shown.

[0027] Figures 5A-5B This is a schematic diagram illustrating different manufacturing stages of an electrode sheet according to another embodiment of this application.

[0028] Figure 6 A schematic diagram of an electrode sheet according to yet another embodiment of this application is shown.

[0029] Figure 7 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0030] Figure 8 A cross-sectional schematic diagram of a secondary battery according to an embodiment of this application is shown.

[0031] Figure 9 yes Figure 8 A cross-sectional schematic diagram of the electrode assembly of the secondary battery.

[0032] Figure 10 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation

[0033] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0034] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0035] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0036] 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 intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the

[0037] For the sake of description, "first," "second," "third," etc. can be used herein to distinguish between different components of one figure or series of figures. The "first," "second," "third," etc. are not intended to describe corresponding components.

[0038] A secondary battery refers to a battery that can be used continuously by activating active materials through charging after discharging the battery. The types of secondary batteries can include a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, a lithium-ion battery, a polymer lithium-ion battery, etc. The electrode assembly of a secondary battery mainly includes a positive electrode tab and a negative electrode tab, and the positive electrode tab and the negative electrode tab are separated by a separator. The positive electrode tab, the negative electrode tab, and the separator are formed into an electrode assembly in a winding or stacking manner, and the electrode assembly is sealed in a case to form a secondary battery.

[0039] The positive electrode tab can include a positive electrode current collector and a positive electrode active material layer coated on part of the surface of the positive electrode current collector. The negative electrode tab can include a negative electrode current collector and a negative electrode active material layer coated on part of the surface of the negative electrode current collector. In some embodiments, for example, in a lithium-ion battery, the material of the positive electrode current collector can be aluminum. The positive electrode active material layer can include a positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganate, etc. For a high-nickel ternary lithium battery, the positive electrode active material can be a ternary material composed of nickel, cobalt, manganese (or aluminum). The material of the negative electrode current collector can be copper. The negative electrode active material layer can include a negative electrode active material, which can be carbon or silicon, etc. The material of the separator can be, for example, PP (polypropylene) or PE (polyethylene), etc.

[0040] Figures 1A-1F is a schematic diagram showing different manufacturing stages of manufacturing a tab according to an embodiment of the present application. First, referring to Figure 1AAs shown, the current collector 110 is coated with an active material layer 130 on both of the side surfaces thereof in the thickness direction. The active material layer 130 can be coated on the current collector 110 by a coating device. An edge portion 110e of the current collector 110 in the width direction is not coated with the active material layer 130 to form an empty foil region. In some embodiments in which the electrode tab is formed as a negative electrode tab, the current collector 110 is a negative electrode current collector, and the active material layer 130 is a negative electrode active material layer. In some embodiments, the material of the negative electrode current collector can be, for example, copper, and the thickness can be 4.5-6 micrometers. In some embodiments in which the electrode tab is formed as a positive electrode tab, the current collector 110 is a positive electrode current collector, and the active material layer 130 is a positive electrode active material layer. In some embodiments, the material of the positive electrode current collector can be aluminum, and the thickness can be 10-12 micrometers. After the active material layer 130 is coated, the current collector 110 and the active material layer 130 can be cut along the dashed line L1, thereby obtaining Figure 1B a single electrode assembly 100 for forming a single electrode tab 100 as shown in the middle.

[0041] Referring to Figure 1C As shown, the current collector 110 is coated with an active material layer 130 on both of the side surfaces thereof in the thickness direction. The active material layer 130 can be coated on the current collector 110 by a coating device. An edge portion 110e of the current collector 110 in the width direction is not coated with the active material layer 130 to form an empty foil region. In some embodiments in which the electrode tab is formed as a negative electrode tab, the current collector 110 is a negative electrode current collector, and the active material layer 130 is a negative electrode active material layer. In some embodiments, the material of the negative electrode current collector can be, for example, copper, and the thickness can be 4.5-6 micrometers. In some embodiments in which the electrode tab is formed as a positive electrode tab, the current collector 110 is a positive electrode current collector, and the active material layer 130 is a positive electrode active material layer. In some embodiments, the material of the positive electrode current collector can be aluminum, and the thickness can be 10-12 micrometers. After the active material layer 130 is coated, the current collector 110 and the active material layer 130 can be cut along the dashed line L1, thereby obtaining Figure 1D and Figure 1E As shown, the current collector 110 is coated with an active material layer 130 on both of the side surfaces thereof in the thickness direction. The active material layer 130 can be coated on the current collector 110 by a coating device. An edge portion 110e of the current collector 110 in the width direction is not coated with the active material layer 130 to form an empty foil region. In some embodiments in which the electrode tab is formed as a negative electrode tab, the current collector 110 is a negative electrode current collector, and the active material layer 130 is a negative electrode active material layer. In some embodiments, the material of the negative electrode current collector can be, for example, copper, and the thickness can be 4.5-6 micrometers. In some embodiments in which the electrode tab is formed as a positive electrode tab, the current collector 110 is a positive electrode current collector, and the active material layer 130 is a positive electrode active material layer. In some embodiments, the material of the positive electrode current collector can be aluminum, and the thickness can be 10-12 micrometers. After the active material layer 130 is coated, the current collector 110 and the active material layer 130 can be cut along the dashed line L1, thereby obtaining Figure 1E is Figure 1D a cross-sectional view of Figure 1D , a plurality of tabs 150 are formed at intervals along the length direction of the electrode tab 100. The uncut portions of the current collector 110 and the active material layer 130 can be referred to as a tab body 160. Referring to Figure 1E , the tab body 160 includes the current collector 110 and the active material layer 130, in which the active material layer 130 covers both of the surfaces of the current collector 110 in the thickness direction. In addition, a thinned region 130e can be formed at the edge of the active material layer 130 in the direction D1 (which can be referred to as a first direction), and the thinned region 130e is connected to the uniformly coated region of the active material layer 130. The thickness of the thinned region 130e gradually decreases in the direction D1.

[0042] The tab 150 extends from the tab body 160 along a direction D1 (parallel to the width direction of the tab). The tab 150 is connected to a first edge 160e of the tab body 160, which extends along a direction D2 (may be referred to as a second direction) perpendicular to the direction D1. The first edge 160e is disposed on both sides of the tab 150 in the direction D1. The direction D2 can be the width direction of the tab 150, and the width of each tab 150 can decrease as the distance from the tab body 160 increases. In the tab width direction, each tab 150 can have a maximum width c1 and a minimum width c2. Specifically, in the present embodiment, the tab 150 can include a tab blank area 152 formed by the current collector 110 not covered by the active material layer 130. The tab 150 can also include a tab coated area 154 connected between the tab blank area 152 and the tab body 160. The tab coated area 154 protrudes from the edge 160e of the tab body 160 perpendicular to the direction D1. Moreover, the active material layer 130 also coats the tab coated area 154. The present application illustrates the tab formed by cutting the current collector coated with active material, and the tab involved in the present application can also be connected to the tab body 160 by other means such as welding.

[0043] Referring to Figure 1F A partial enlarged view of the area A1 of the tab 100 is shown in FIG. 2B, which shows the reinforcing ribs 190 formed on the surface of each tab 150. In some embodiments, the reinforcing ribs 190 can be formed before or after the tab is cut. Preferably, the reinforcing ribs are formed on the tab before the tab is cut. In some embodiments, the tab is rolled with an embossing roller before the tab is cut to form reinforcing ribs on the tab, and this use of the embossing roller to form reinforcing ribs can also be referred to as embossing.

[0044] Figure 2 A partial enlarged view of the area A1 of the tab 100 is shown in FIG. 2B, which shows the reinforcing ribs 190 formed on the surface of each tab 150. In some embodiments, the reinforcing ribs 190 can be formed before or after the tab is cut. Preferably, the reinforcing ribs are formed on the tab before the tab is cut. In some embodiments, the tab is rolled with an embossing roller before the tab is cut to form reinforcing ribs on the tab, and this use of the embossing roller to form reinforcing ribs can also be referred to as embossing. Figure 1F A partial enlarged view of the area A1 of the tab 100 is shown in FIG. 2B, which shows the reinforcing ribs 190 formed on the surface of each tab 150. In some embodiments, the reinforcing ribs 190 can be formed before or after the tab is cut. Preferably, the reinforcing ribs are formed on the tab before the tab is cut. In some embodiments, the tab is rolled with an embossing roller before the tab is cut to form reinforcing ribs on the tab, and this use of the embossing roller to form reinforcing ribs can also be referred to as embossing. Figure 2 As shown in FIG. 2B, the tab 150 can be provided with a second reinforcing rib area 192 and a first reinforcing rib area 191 along the direction D1. The second reinforcing rib area 192 is disposed between the first reinforcing rib area 191 and the active material layer 130. The first reinforcing rib area 191 and the second reinforcing rib area 192 are disposed in the tab blank area 152. The second reinforcing rib area 192 is closer to the junction 130b between the active material layer 130 and the tab blank area 152. The second reinforcing rib area 192 is a region of the tab blank area 152 closer to the junction 130b, and the first reinforcing rib area 191 is a region of the tab blank area 152 farther from the junction 130b.

[0045] The reinforcing ribs 190 are disposed in both the first reinforcing rib area 191 and the second reinforcing rib area 192. Figure 3Aand Figure 3B are schematic cross-sectional views of the first and second reinforcement rib regions 191 and 192, respectively, and the cross-sections are perpendicular to the thickness direction of the tab and pass through the tab along the length direction of the tab. Reference is made to Figure 3A and Figure 3B The reinforcement ribs 190 in the first reinforcement rib region 191 have a depth H1, and the reinforcement ribs 190 in the second reinforcement rib region 192 have a depth H2. The depths H1 and H2 refer to the depth of the recesses, for example, caused by rolling, of the surface of the tab in the region of the reinforcement ribs, specifically the surface of the current collector 110 in the present embodiment. The depth H1 of the reinforcement ribs 190 in the first reinforcement rib region 191 is greater than the depth H2 of the reinforcement ribs 190 in the second reinforcement rib region 192. In one embodiment, the minimum depth of the reinforcement ribs in the first reinforcement rib region 191 is greater than the maximum depth of the reinforcement ribs in the second reinforcement rib region 192. In another embodiment, the average depth of the reinforcement ribs in the first reinforcement rib region 191 is greater than the average depth of the reinforcement ribs in the second reinforcement rib region 192.

[0046] The deeper the reinforcement ribs formed on the tab, the less likely the tab is to be folded over, provided that the tab is not cracked. However, the second reinforcement rib region 192 is adjacent to the active material layer 130, and if the depth of the reinforcement ribs in the second reinforcement rib region 192 is too deep, the stress on the second reinforcement rib region during rolling is also greater, and the active material at the interface 130b is likely to be detached. Therefore, by setting the depth H2 of the reinforcement ribs 190 in the second reinforcement rib region 192 to be less than the depth H1 of the reinforcement ribs 190 in the first reinforcement rib region 191, the present technical solution can avoid the active material near the reinforcement ribs at the root of the tab in the prior art being detached due to excessive stress caused by the greater depth during forming (for example, rolling forming), and can reduce the likelihood of the tab being folded over.

[0047] In addition, the tab 150 can also be provided with a third reinforcement rib region 193, which is located at the surface of the portion of the tab coating area 154 adjacent to the interface 130b, and the third reinforcement rib region 193 is provided with reinforcement ribs. By extending the reinforcement ribs 190 into the tab coating area 154, the bending resistance provided by the reinforcement ribs to the tab can be increased.

[0048] Figure 3C is a schematic cross-sectional view of the third reinforcement rib region 193, and the cross-section is perpendicular to the thickness direction of the tab and passes through the tab along the length direction of the tab. Reference is made to Figure 3CIn some embodiments, the depth H3 of the ribs 190 in the third rib region 193 is also greater than the depth H2 of the ribs 190 in the second rib region 192, so as to increase the bending resistance provided by the ribs in the third rib region 193. Further, the second rib region 192 with the smallest rib depth can be used to transition between the first rib region 191 and the third rib region 193. The technical solution of the present application sets the depth of the ribs in the second rib region 192 to be shallower than the depths of the ribs in the first rib region 191 and the third rib region 193, so that the depth of the ribs 190 is configured to change from the first rib region 191 to the third rib region 193, and the second rib region 192 with the smaller depth is used to transition between the first rib region 191 and the third rib region 193, which can make the electrode assembly easier to bend when it is put into the shell, reduce the possibility of tearing of the tab, and avoid the stress generated by bending from being transmitted to the junction 130b of the tab coating area 154, causing the active material to fall off.

[0049] If the second rib region 192 with the smaller depth is not set to transition, the tab will be prone to folding at the junction 130b.

[0050] In some embodiments, the ribs in the first rib region 191 and the ribs in the second rib region 192 form at least one continuous and uninterrupted rib. In some embodiments, the ribs in the third rib region 193 and the ribs in the second rib region 192 form a continuous and uninterrupted rib. In actual implementation, the embossing roller can be designed to have a convex rib pattern, and the ribs can be formed by rolling the electrode tab with the embossing roller.

[0051] In some embodiments, the ratio between the depth H3 of the ribs in the third rib region 193 and the thickness of the active material layer 130 where the ribs are located is 30%-85%. In one example, the thickness of the active material layer in the third rib region 193 is uniform. In another example, the active material layer in the third rib region 193 has a thinned area 130e, and it should be understood that at least a part of the ribs in the third rib region 193 will be located in the thinned area 130e of the active material layer 130, and for this part of the ribs, the ratio between the depth of the ribs at each position in the third rib region 193 and the thickness of the active material layer at that position is 30%-85%.

[0052] If the ratio of the depth of the reinforcing ribs in the third reinforcing rib region 193 to the active material layer 130 is greater than 85%, the depth of the reinforcing ribs in the third reinforcing rib region 193 is too deep, which can easily cause the active material to fall off. If the ratio is less than 30%, the depth of the reinforcing ribs in the third reinforcing rib region 193 is too small, and the bending strength of the tab is small. By setting the ratio between the depth of the reinforcing ribs in the third reinforcing rib region 193 and the thickness of the active material layer 130 to 30%-85%, the active material can be prevented from falling off, and sufficient bending strength of the tab can be provided.

[0053] In some embodiments, the reinforcing ribs in the first reinforcing rib region 191, the reinforcing ribs in the second reinforcing rib region 192, and the reinforcing ribs in the third reinforcing rib region 193 form at least one continuous reinforcing rib, connecting the tab blank area 152 and the tab coating area 154 into one whole, and further supporting the tab blank area 152 by the active material layer 130 coated on the tab coating area 154 to improve the bending resistance of the tab. In actual implementation, the embossing roller can be designed to have a convex rib pattern, and the reinforcing ribs can be formed by rolling the tab with the embossing roller.

[0054] In the present embodiment, the reinforcing ribs 190 on the tab 150 can include a plurality of V-shaped structure reinforcing ribs connected in sequence, each V-shaped structure reinforcing rib being formed by two reinforcing ribs arranged at an angle, and the V-shaped angle at the bottom of each V-shaped structure reinforcing rib extending into the tab coating area 154. The reinforcing ribs in the third reinforcing rib region 193 can be the part of the reinforcing ribs 190 extending into the tab coating area 154. Therefore, the reinforcing ribs in the third reinforcing rib region 193 include at least two reinforcing ribs arranged at an angle, and the two reinforcing ribs are connected to each other to form at least one V-shaped structure 199. In the case of multiple V-shaped structures 199, the multiple V-shaped structures 199 in the third reinforcing rib region 193 can be spaced apart along the length direction of the tab. Such V-shaped structure of the reinforcing ribs 190 can provide stronger tab stability, and the V-shaped structure 199 extending into the tab coating area 154 can further improve the bending resistance of the tab 150.

[0055] In some embodiments, the reinforcing ribs within the third reinforcing rib region 193 have end portions 198, which in this embodiment are the end portions of the V-shaped structures 199, in the direction opposite to the direction D1. Between the end portions 198 and the edge 160e of the pole piece body 160 in the direction opposite to the direction D1, there is a gap d, the size of which in the direction opposite to the direction D1 is > 0. If the reinforcing ribs 190 enter the area of the pole piece body 160, at this time, the reinforcing ribs 190 are likely to overlap with the projection of the active material layer of another pole piece (for example, the positive pole piece) in the secondary battery, thereby causing the occurrence of problems such as edge lithium precipitation in the secondary battery. By setting the gap d to be greater than zero, the end portions 198 of the reinforcing ribs 190 are spaced apart from the edge 160e of the pole piece body 160, so as to avoid the reinforcing ribs 190 from entering the area of the pole piece body 160, which can avoid causing the occurrence of problems such as edge lithium precipitation in the secondary battery when the pole piece 100 is used to form a secondary battery.

[0056] Figure 3D is a schematic view of a continuous reinforcing rib 190 according to an embodiment of the present application. Referring to Figure 3D , each continuous reinforcing rib 190 has at least one first transition portion 1901 and at least one second transition portion 1902, the first transition portion 1901 and the second transition portion 1902 are alternately arranged in the tab width direction perpendicular to the direction D1 and are connected by a connecting portion 1903. The first transition portion 1901 protrudes along the direction D1, and the second transition portion 1902 protrudes in the opposite direction of the direction D1. In this embodiment, the first transition portion 1901 and the second transition portion 1902 are respectively circular arc transition regions. The inner angle of the first transition portion 1901 is directed towards the first edge 160e (for example, see Figure 1D ), and the inner angle of the second transition portion 1902 is directed towards the second edge 150e (for example, see Figure 1D ). The maximum width of the circular arc transition region (the first transition portion 1901 and the second transition portion 1902) in the radius direction is y1 (at this time, y1 is the maximum width y of a single continuous reinforcing rib 190), and the width of the connecting portion 1903 perpendicular to the extension direction thereof is y2, and the ratio of y1 to y2 is in the range of 1.2-2.5, i.e. 1.2≤y1 / y2≤2.5. If y1 / y2 is lower than the lower limit value 1.2, it is difficult to form a smooth chamfer of the circular arc transition region, and the tab 150 is easily damaged during the formation (for example, rolling) of the reinforcing rib. If y1 / y2 is higher than the upper limit value 2.5, the area between the adjacent continuous reinforcing ribs 190 is prone to wrinkles during the formation (for example, rolling) of the reinforcing rib, for example, the triangular area formed by the continuous reinforcing rib 190 is prone to wrinkles, which is not conducive to the subsequent welding of the tab 150.

[0057] In some embodiments, the ratio of the maximum width c1 (as described above with reference to Figure 1D ) of the tab 150 to b is in the range of 1.5-3, 1.5≤c1 / b≤3. The ratio of the minimum width c2 (as described above with reference to Figure 1D ) of the tab 150 to b is in the range of 1.5-3, 1.5≤c2 / b≤3. When c1 / b and / or c2 / b is greater than 1.5, it is possible to form at least one W-shaped continuous reinforcement rib 190 on the tab 150 after the reinforcement rib is formed, for example, by rolling, to ensure the reinforcement effect; however, if c1 / b and / or c2 / b is too large, for example, greater than 3, the continuous reinforcement rib 190 formed at this time is too dense in the width direction of the tab, which is prone to crushing the tab.

[0058] In some embodiments, the ratio of the width (for example, any one of y1 and y2 described above) of the at least one continuous reinforcement rib 190 to the depth thereof at different positions is a, specifically, the ratio of the width of the at least one continuous reinforcement rib 190 to the depth of the at least one continuous reinforcement rib 190 at different positions along the thickness direction of the tab is a, 1.1≤a≤6.67. If the ratio a is less than 1.1, the width of the reinforcement rib 190 is relatively narrow, the stress concentration point of the edge is concentrated, and the problem of crushing is prone to occur. If the ratio a is greater than 6.67, the depth of the reinforcement rib is relatively small, and after the reinforcement rib is formed (for example, embossed by an embossing roller), the depth of the concave part of the reinforcement rib cannot meet the reinforcement requirement of the tab.

[0059] Figure 4 A cross-sectional schematic view of a tab 100A according to some other embodiments is shown. Figure 4 Aspects of the tab 100A shown can be similar to the above description of the tab 100 with reference to Figures 1A-3D The differences of the tab 100A are described below. With reference to Figure 4 shown, in the present embodiment, the tab 100A can further include a conductive layer 125. A portion of the conductive layer 125 is located between the active material layer 130 and the current collector 110 of the tab body 160. Another portion of the conductive layer 125 extends along the direction D1 to the third reinforcement rib region 193, and is arranged between the active material layer and the current collector 110 in the third reinforcement rib region 193. The other portion of the conductive layer 125 is covered by the active material layer 130 in the tab coating area of the tab 150. The active material layer 130 in the third reinforcement rib region 193 can exceed the conductive layer 15 along the direction D1. Among them, the end of the reinforcement rib in the third reinforcement rib region 193 (such as Figure 2The end portion 198 in the thickness direction of the pole piece overlaps with the conductive layer 125, i.e., the end portion of the reinforcing rib in the third reinforcing rib region 193 extends onto the active material layer 130 above the conductive layer 125. The conductive layer 125 can be a metal conductive layer, a carbon material layer, a composite material of carbon material and metal particles, or the like. In this embodiment, by providing the conductive layer 125 in the pole piece, the adhesion and / or support of the active material by the conductive layer can be utilized to avoid the active material layer 130 from falling off during the formation of the reinforcing rib.

[0060] Figures 5A-5B are schematic diagrams showing different manufacturing stages of manufacturing the pole piece 100B according to another embodiment of the present application. In this embodiment, as shown in Figure 5A , the side of the current collector 110 of the pole piece 100B which is not coated with the active material layer 130 can be tab cut according to the dashed line L3. After the tab cut, as shown in Figure 5B , a plurality of tabs 150’ are formed which are spaced apart along the length direction of the pole piece 100B. The tabs 150’ extend out of the first edge 160e of the pole piece body 160 along the direction D1. Unlike the above-described embodiments with reference to Figures 1A-3D , in the pole piece 100B of this embodiment, the tabs 150’ are only composed of the tab blank foil region. The junction 130b’ of the active material layer 130 and the tab 150’ (i.e., the tab blank foil region) can be aligned with the first edge 160e along the length direction of the pole piece.

[0061] In this embodiment, similar to the above-described embodiments with reference to Figures 1A-3D , the tabs 150’ can include a first reinforcing rib region 191 and a second reinforcing rib region 192. The second reinforcing rib region 192 is closer to the junction 130b’ of the active material layer 130 and the tab 150’. The depth of the reinforcing rib 190 in the first reinforcing rib region 191 is greater than the depth of the reinforcing rib 190 in the second reinforcing rib region 192. By setting the depth of the reinforcing rib in the second reinforcing rib region 192 to be less than the depth of the reinforcing rib in the first reinforcing rib region 191, the depth of the reinforcing rib in the second reinforcing rib region 192 can be prevented from being too deep to cause the active material to fall off; at the same time, if the reinforcing rib in the second reinforcing rib region is cancelled, the tab can be folded over in the second reinforcing rib region.

[0062] In addition, the pole piece 100B can include a third reinforcing rib region 193 which is located at the surface of the part of the active material layer 130 adjacent to the junction 130b’. The reinforcing rib 190 extends into the region of the pole piece body 160 so that the third reinforcing rib region 193 is provided with the reinforcing rib. The reinforcing rib in the third reinforcing rib region 193 can be utilized to increase the anti-folding strength of the reinforcing rib provided to the tab.

[0063] In some embodiments, the depth of the ribs within the third rib region 193 is greater than the depth of the ribs within the second rib region 192. In this way, the second rib region 192, which has the smallest depth, can be used to transition between the first rib region 191 and the third rib region 193. By setting the depth of the ribs within the second rib region 192 to be shallower than the depth of the ribs within both the first rib region 191 and the third rib region 193, the second rib region 192, which has a smaller depth, is used to transition between the first rib region 191 and the third rib region 193, which can make the tab folding process easier when the electrode assembly is inserted into the case, reduce the possibility of tab tearing, and avoid the stress generated by folding from being transmitted to the interface 130b’ to cause active material to fall off.

[0064] Figure 6 A schematic diagram of a tab 100C according to yet another embodiment of the application is shown. Reference is made to Figure 6 In this embodiment, in the tab 100C of this embodiment, the tab 150’ is composed of only a tab empty foil region. The interface 130b’ between the active material layer 130 and the tab 150’ (i.e. the tab empty foil region) can be aligned with the first edge 160e along the tab length direction. The tab 150’ can include a first rib region 191 and a second rib region 192. The second rib region 192 is closer to the interface 130b’ between the active material layer 130 and the tab 150’. The depth of the ribs within the first rib region 191 can be greater than the depth of the ribs within the second rib region 192. By setting the depth of the ribs within the second rib region 192 to be smaller than the depth of the ribs within the first rib region 191, it can be avoided that the depth of the ribs within the second rib region 192 is too deep to cause active material to fall off; at the same time, the possibility of tab folding is reduced.

[0065] In this embodiment, the ribs 190 do not extend onto the active material layer 130, and the tab 150’ is not provided with a third rib region. Other aspects of the tabs 100B, 100C can be similar to the tab 100 described above, and are not repeated here.

[0066] Figure 7 A perspective schematic diagram of a secondary battery according to an embodiment of the application is shown. Figure 8 A cross-sectional schematic diagram of a secondary battery according to an embodiment of the application is shown. Figure 9 is Figure 8 a cross-sectional schematic diagram of an electrode assembly of a secondary battery in

[0067] In combination with Figures 7-8As shown, the secondary battery 500 can include a case 200 including a peripheral sidewall 109 and an end wall 111 connected to one end of the peripheral sidewall 109, and an opening 205 is provided at the other end of the peripheral sidewall 109 opposite to the end wall 111. A top cover assembly 220 is covered on the opening 205 of the case 200 for defining a receiving cavity together with the case 200, and the electrode assembly 120 is located in the receiving cavity.

[0068] The end wall 111 is the height direction Z of the secondary battery 500 in the direction of the top cover assembly 220. The height direction Z can correspond to the above-mentioned direction D1. In the present embodiment, two electrode assemblies 120 are stacked in the case 200 along the thickness direction of the electrode assembly 120. In other embodiments, more than two electrode assemblies 120 can be provided in the case 200.

[0069] In some embodiments, referring to Figure 9 As shown, the electrode assembly 120 is a winding body formed by winding the first tab 201, the second tab 202, and the separator 204 between the first tab 201 and the second tab 202. In other embodiments, the electrode assembly 120 can also be a laminated body formed by sequentially laminating the first tab 201, the second tab 202, and the separator 204 between the first tab 201 and the second tab 202. The electrode assembly 120 can be flat. Correspondingly, the case 200 can have a flat shape and have a cuboid shape. The plurality of first lugs 121 of the first tab 201 and the plurality of second lugs 122 of the second tab 202 can be stacked in the thickness direction of the electrode assembly 120, respectively.

[0070] In combination with Figures 7-9 As shown, the top cover assembly 220 includes a top cover body 221 and a first electrode terminal 223 and a second electrode terminal 224 provided on the top cover body 221. The first electrode terminal 223 and the second electrode terminal 224 can pass through the top cover body 221 and be insulated from the top cover body 221. One of the first electrode terminal 223 and the second electrode terminal 224 is a positive electrode terminal, and the other is a negative electrode terminal. The electrode assembly 120 is provided with lugs at one end thereof, and in the present embodiment, the first lugs 121 and the second lugs 122 at one end of the electrode assembly 120 are connected to the corresponding first electrode terminal 223 and the second electrode terminal 224, respectively. In some embodiments, the first lugs 121 and the second lugs 122 can be connected to the first electrode terminal 223 and the second electrode terminal 224, respectively, through corresponding adapter pieces 226. The first lugs 121 and the second lugs 122 can be welded to the adapter pieces 226 after being bent.

[0071] In some embodiments, one of the first tab 201 and the second tab 202 is a positive electrode tab, and the other is a negative electrode tab. In some embodiments, at least one of the positive electrode tab and the negative electrode tab of the electrode assembly 120 is the above-mentioned tab 100, the tab 100A, the tab 100B, or the tab 100C. Correspondingly, one of the first tab 121 and the second tab 122 is a positive electrode tab, and the other is a negative electrode tab. At least one of the positive electrode tab and the negative electrode tab of the electrode assembly 120 is the corresponding tab 150 or the tab 150' of the above-mentioned tab 100, the tab 100A, the tab 100B, or the tab 100C. In some embodiments, the negative electrode tab of the electrode assembly 120 is the above-mentioned tab 100, the tab 100A, the tab 100B, or the tab 100C, and the negative electrode tab is the above-mentioned tab 150 or the tab 150'.

[0072] It should be understood that Figures 7-9 The above-mentioned tab 100, the tab 100A, the tab 100B, or the tab 100C of the present application can also be used to form any other appropriate type of secondary battery, such as a soft package battery, a cylindrical battery, etc.

[0073] Figure 10 A schematic diagram of the electronic device according to the embodiments of the present application is shown when the electronic device is a vehicle. Referring to FIG. 1, the electronic device according to the embodiments of the present application is a vehicle 1. Figure 10In some embodiments, the electronic device 1000 can be a vehicle. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, but is not limited thereto. The working part of the electronic device 1000 can be a vehicle body. The battery pack 1002 can be arranged at the bottom of the vehicle body and provide power support for driving of the vehicle or operation of electrical elements in the vehicle. However, in some other embodiments, the electronic device 1000 can also be a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, or the like. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, or the like. The working part can obtain power from the battery pack 1002 and make corresponding working unit components, such as a fan blade rotating unit, a dust suction working unit of a dust collector, or the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, an electric airplane toy, or the like. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, or the like. The battery pack 1002 can include a plurality of secondary batteries, such as the secondary battery 500 described above.

[0074] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, or the like within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pole piece, characterized in that, Comprise: a pole piece body comprising a current collector and an active material layer, the current collector having two surfaces opposite along a thickness direction of the current collector, the two surfaces respectively coated with the active material layer; and a tab extending out from the pole piece body along a first direction, the tab being provided with a second rib area and a first rib area along the first direction, wherein, along the first direction, the second rib area is provided between the first rib area and the active material layer, and the first rib area and the second rib area are provided with ribs, 2. The pole piece of claim 1, wherein the tab comprises a tab empty foil area and a tab coated area, the tab coated area being connected between the tab empty foil area and the pole piece body, and the active material layer is also coated on the tab coated area, the tab is further provided with a third rib area, the third rib area being located at a part of the surface of the active material layer in the tab coated area, the ribs in the third rib area form a continuous rib with the ribs in the second rib area, wherein the depth of the ribs in the third rib area is greater than the depth of the ribs in the second rib area.

3. The pole piece of claim 2, wherein the ratio between the depth of the ribs in the third rib area and the thickness of the active material layer where the ribs are located is 30%-85%.

4. The pole piece of claim 2, wherein the ribs in the first rib area, the ribs in the second rib area and the ribs in the third rib area form at least one continuous rib; or the ribs in the first rib area and the ribs in the second rib area form at least one continuous rib.

5. The pole piece of claim 4, wherein the ratio between the width of the at least one continuous rib and the corresponding depth of the at least one continuous rib is a, and 1.1≤a≤6.

67.

6. The pole piece of claim 2, wherein the tab is connected to a first edge of the pole piece body, the first edge extending along a second direction perpendicular to the first direction, the ribs in the third rib area have an end portion in the opposite direction of the first direction, and the end portion has a gap between the first edge and the end portion along the opposite direction of the first direction.

7. The pole piece of claim 6, wherein the ribs in the third rib area comprise two ribs arranged at an angle, and the two ribs are connected to each other to form a V-shaped structure.

8. The pole piece of claim 2, wherein Further comprise: a conductive layer, a part of the conductive layer being located between the active material layer and the current collector of the pole piece body, another part of the conductive layer extending to the third rib area along the first direction, and the active material layer in the tab coated area covering the other part of the conductive layer, The reinforcing ribs in the third reinforcing rib region have end portions in the opposite direction of the first direction, which overlap the conductive layer in the thickness direction of the pole piece.

9. The pole piece of claim 4, wherein, The tab is connected to a first edge of the pole piece body, and a second edge of the tab is disposed on both sides of the first edge in the first direction; Each of the continuous reinforcing ribs has at least one first transition portion and at least one second transition portion, the first and second transition portions are alternately disposed in a tab width direction perpendicular to the first direction and connected by a connecting portion; The first and second transition portions are circular arc transition regions, the inner angle of the first transition portion faces the first edge, and the inner angle of the second transition portion faces the second edge; the maximum width of the circular arc transition region is y1, and the width of the connecting portion perpendicular to the extension direction of the connecting portion is y2, 1.2≤y1 / y2≤2.

5.

10. The pole piece of claim 9, wherein, The distance between the vertices of two adjacent first transition portions of a single continuous reinforcing rib is b, In the tab width direction, the tab has a maximum width c1 and a minimum width c2, wherein: 1.5≤c1 / b≤3, and / or, 1.5≤c2 / b≤3.

11. A secondary battery characterized by comprising: Comprising: An electrode assembly comprising a positive electrode pole piece, a negative electrode pole piece, and a separator between the positive electrode pole piece and the negative electrode pole piece, At least one of the positive electrode pole piece and the negative electrode pole piece is the pole piece of any one of claims 1-10.

12. An electronic device, comprising: A secondary battery comprising the secondary battery of claim 11. A secondary battery comprising the secondary battery of claim 11.

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