Pole piece, secondary battery, and electronic device

Abstract

The utility model relates to a battery technical field discloses a kind of pole piece, secondary battery and electronic device, can improve the welding effect of tab and adapter piece.Pole piece includes pole piece main body and multiple tabs, tab is connected in pole piece main body along the side of first direction, multiple tabs are arranged along second direction, wherein, first direction is perpendicular to second direction.Pole piece main body includes current collector and active material layer coated in the surface of opposite two sides of current collector, the thickness of current collector is d μm, 4≤d≤5.5.Tab has tab white area, tab white area includes the welding area for being welded with adapter piece in the side of tab white area away from pole piece main body, the size of welding area in first direction is Amm, the spacing between welding area and the side edge of tab white area close to pole piece main body in first direction is Bmm, 4≤B / A≤7.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode, a secondary battery, and an electronic device. Background Technology

[0002] Secondary batteries (also known as rechargeable batteries) are those that, after being discharged, can be recharged by an external power source, converting electrical energy back into chemical energy and storing it, thus allowing for repeated charging and discharging. For prismatic batteries, they typically consist of two electrode assemblies. After the tabs of each battery assembly are welded to the adapter plate, the tabs are fixed inside the battery casing in a bent state.

[0003] Typically, electrode plates include current collectors used for output and input current. The thickness of the current collector is generally greater than or equal to 6μm. However, as energy density requirements increase, the thickness of the current collector needs to be reduced. This leads to a tendency for the tabs to fold during the winding or stacking process. To improve this folding phenomenon, the height of the tabs is usually reduced. However, reducing the tab height reduces the space reserved for bending, affecting the welding effect between the tabs and the adapter plate. Utility Model Content

[0004] To address the issue of electrode tab folding, this invention proposes an electrode sheet, a secondary battery, and an electronic device that can improve the welding effect between the electrode tab and the adapter sheet.

[0005] To achieve the above objectives, in a first aspect, this utility model provides an electrode sheet, comprising an electrode sheet body and a plurality of tabs, wherein the tabs are connected to one side of the electrode sheet body along a first direction, and the plurality of tabs are arranged along a second direction, wherein the first direction is perpendicular to the second direction; the electrode sheet body includes a current collector and an active material layer coated on opposite sides of the current collector, wherein the thickness of the current collector is dμm, 4≤d≤5.5;

[0006] The tab has a tab blank area, which includes a welding area located on the side of the tab blank area away from the electrode body for welding with the adapter piece. The welding area has a dimension of A mm in the first direction, and the distance between the welding area and the edge of the tab blank area near the electrode body in the first direction is B mm, where 4 ≤ B / A ≤ 7.

[0007] The electrode sheet provided by this utility model has a tab clearance area located between the welding area and the electrode sheet body, which serves as a bending reserve space for the tab. The size of the bending reserve space in the first direction is related to the value of B. By limiting 4≤B / A≤7, on the one hand, the size of the welding area can be improved, increasing the reliability of the welding. On the other hand, it ensures that the bending reserve size of the tab is sufficient. When the tab is welded to the adapter piece and is in a bent state, the large bending reserve size of the tab results in a small overall tensile force on the tab, preventing the active material layer near the tab clearance area from falling off, thereby further improving the welding quality.

[0008] In some possible implementations, the side of the electrode tab away from the electrode body is provided with R-angles at both ends in the second direction, the minimum distance between the two R-angles is Lmm, and the size of the welding area in the second direction is Cmm, wherein 0.91≤C / L≤0.98.

[0009] In some possible implementations, A and C satisfy the following condition: 2.6 ≤ C / A ≤ 4.2.

[0010] In some possible implementations, the tab has a dimension of H mm in the first direction, where 10 ≤ H ≤ 35.

[0011] In some possible implementations, the tab blank area is provided with reinforcing ribs on the side of the welding area facing the electrode body, and the reinforcing ribs protrude from the tab along the thickness direction of the tab;

[0012] The shape of the reinforcing rib is one or more of the following: dot-shaped, strip-shaped, wavy, and zigzag-shaped.

[0013] In some possible implementations, the tab further includes a coating area located between the tab blank area and the tab body, and the reinforcing rib extends from the tab blank area to the coating area; and / or

[0014] The electrode body includes an electrode blank area, which is located between the active material layer and the electrode tab, and the reinforcing rib extends from the electrode tab blank area to the electrode blank area.

[0015] In some possible implementations, the electrode is a negative electrode and the current collector is a copper foil.

[0016] In some possible implementations, each of the tabs is the same size in the first direction, or at least two of the tabs are different in size in the first direction.

[0017] In a second aspect, the present invention provides a secondary battery, including a casing, a top cover, and two sets of electrode assemblies disposed within the casing. The electrode assembly includes a positive electrode, a separator, and a negative electrode. The positive electrode, the separator, and the negative electrode are layered and then wound or stacked to form the electrode assembly. The negative electrode is an electrode as described in any possible embodiment of the first aspect.

[0018] The top cover fits onto the housing, and the top cover has an adapter piece on the side facing the housing;

[0019] The electrode assembly is located inside the housing. The tab of each negative electrode sheet includes a bending portion and a welding portion. The bending portion is connected between the welding portion and the electrode sheet body. The welding area is disposed in the welding portion. At least part of the portion between the welding area and the blank area of ​​the tab near the electrode sheet body is disposed in the bending portion.

[0020] The bending portion bends relative to the electrode body toward the other electrode assembly, and the welding portion is connected to the adapter piece through the welding area.

[0021] Thirdly, this utility model provides an electronic device including a secondary battery as described in the second aspect. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an electronic device in an embodiment of the present utility model;

[0023] Figure 2 This is a schematic diagram of the overall structure of a secondary battery in an embodiment of this utility model;

[0024] Figure 3 This is a cross-sectional view of a secondary battery with its casing removed, as described in an embodiment of this utility model.

[0025] Figure 4 This is a schematic diagram of the electrode assembly in one embodiment of the present utility model;

[0026] Figure 5 This is a schematic diagram showing one state of welding between the electrode tab and the adapter piece in an embodiment of this utility model;

[0027] Figure 6 This is a schematic diagram of the structure of an electrode sheet in an embodiment of this utility model;

[0028] Figure 7 This is a schematic diagram of a single electrode tab and electrode sheet in an embodiment of this utility model;

[0029] Figure 8aA schematic diagram of a structure in which dotted reinforcing ribs are provided in the blank area of ​​the electrode tab in an embodiment of this utility model;

[0030] Figure 8b This is a schematic diagram of another structure in which dotted reinforcing ribs are provided in the blank area of ​​the electrode tab in this utility model embodiment;

[0031] Figure 9a A schematic diagram of a structure in which a strip-shaped reinforcing rib is provided in the blank area of ​​the electrode tab in an embodiment of this utility model;

[0032] Figure 9b This is a schematic diagram of another structure in which a strip-shaped reinforcing rib is provided in the blank area of ​​the electrode tab in this utility model embodiment;

[0033] Figure 10 A schematic diagram of a structure in which a wave-shaped reinforcing rib is provided in the blank area of ​​the electrode tab in an embodiment of this utility model;

[0034] Figure 11 A schematic diagram of a structure in which a zigzag-shaped reinforcing rib is provided in the blank area of ​​the electrode tab in an embodiment of this utility model;

[0035] Figure 12 This is another structure for setting reinforcing ribs in the blank area of ​​the electrode tab in the embodiments of this utility model;

[0036] Figure 13 This is a schematic diagram of another structure of the electrode sheet in an embodiment of this utility model;

[0037] Figure 14 For based on Figure 13 A schematic diagram of a structure in which reinforcing ribs are set in the blank area of ​​the electrode tab;

[0038] Figure 15 This is a schematic diagram of another structure of the electrode sheet in an embodiment of this utility model;

[0039] Figure 16 For based on Figure 15 A schematic diagram of a structure in which reinforcing ribs are set in the blank area of ​​the electrode tab;

[0040] Figure 17 This is a schematic diagram of another structure of the electrode sheet in an embodiment of this utility model.

[0041] In the picture:

[0042] 1000 - Electronic device; 1100 - Body; 1200 - Secondary battery; 1210 - Housing; 1220 - Top cover; 1221 - Adapter piece; 1230 - Electrode assembly; 100 - Electrode; 100a - Positive electrode; 100b - Negative electrode; 110 - Electrode body; 111 - Current collector; 112 - Active material layer; 113 - Electrode blank area; 120 - Tab; 120a - Positive tab; 120b - Negative tab; 121 - Tab blank area; 122 - Welding area; 123 - Radius; 124 - Reinforcing rib; 125 - Coating area; 200 - Separator; M - Bending part; N - Welding part; S1 - First reinforcing area; S2 - Second reinforcing area; S3 - Third reinforcing area. Detailed Implementation

[0043] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0044] With the continuous development of new energy technologies, the application fields of secondary batteries are constantly expanding, and related technologies are also continuously advancing. Types of secondary batteries include nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, lithium-ion batteries, and polymer lithium-ion batteries. For lithium-ion batteries, the thickness of conventional electrode current collectors is greater than or equal to 6μm, but with the increasing demands for energy density, the thickness of the current collector needs to be reduced.

[0045] This application proposes an electrode with a current collector thickness of 4μm to 5μm, which also means that the tab thickness is reduced to 4μm to 5μm. Since the tab has a certain height, the top of the thinned tab is prone to folding. To solve this folding problem, the height of the tab can be reduced. However, since the tab is bent when installed in the battery casing after welding it to the adapter, the reduced height not only affects the welding area with the adapter but also reduces the space reserved for bending, thus affecting the welding effect between the tab and the adapter and negatively impacting the quality of the secondary battery.

[0046] Based on this, the present invention provides an electrode sheet, a secondary battery, and an electronic device that improves the electrode tab folding phenomenon and enhances the welding effect between the electrode tab and the adapter plate, thereby improving the quality of the secondary battery. The electrode sheet, secondary battery, and electronic device are described in detail below with reference to specific embodiments.

[0047] refer to Figure 1 , Figure 1This is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. The electronic device 1000 in this embodiment can be, for example, a vehicle, which may include a body 1100 and a battery pack. The battery pack may include one or more secondary batteries 1200. The battery pack is disposed inside the body 1100 to supply power to the vehicle and ensure its normal operation. In practical applications, 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, etc.

[0048] In other embodiments, the electronic device 1000 may be, for example, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and a power tool, etc. This embodiment does not limit the type of the electronic device 1000.

[0049] Please refer to the above. Figures 2 to 4 In this embodiment, the secondary battery 1200 may include a housing 1210, a top cover 1220, and an electrode assembly 1230. The housing 1210 has an internal accommodating space, and one end of the housing 1210 has an opening. The electrode assembly 1230 can be accommodated in the internal accommodating space of the housing 1210. The top cover 1220 can cover the opening of the housing 1210 and is fixedly connected to the housing 1210, so that the interior of the housing 1210 is in a relatively sealed state.

[0050] like Figure 4 As shown, the electrode assembly 1230 may include a positive electrode 100a, a negative electrode 100b, and a separator 200. The separator 200 is located between the positive electrode 100a and the negative electrode 100b to isolate them and prevent them from contacting each other, thus avoiding a short circuit. The positive electrode 100a, the separator 200, and the negative electrode 100b are simultaneously wound to form the electrode assembly 1230 in a wound state.

[0051] Combination Figure 4 and Figure 5 The positive electrode 100a includes a plurality of positive electrode tabs 120a, which are stacked in the thickness direction of the electrode assembly 1230 after the positive electrode 100a is wound. Similarly, the negative electrode 100b includes a plurality of negative electrode tabs 120b, which are stacked in the thickness direction of the electrode assembly 1230 after the negative electrode 100b is wound.

[0052] like Figures 2 to 5As shown, the electrode assembly 1230 generally consists of two sets, which are stacked within the housing 1210. A connector 1221 is provided on the side of the top cover 1220 facing the housing 1210. When the electrode assembly 1230 is placed inside the housing 1210, the positive electrode tab 120a and the negative electrode tab 120b are both located on the side of the electrode assembly 1230 facing the top cover 1220. During the assembly of the secondary battery, the two electrode assemblies 1230 can be placed on either side of the connector 1221, and the positive electrode tab 120a and the negative electrode tab 120b of each electrode assembly 1230 are welded to the connector 1221 respectively. Subsequently, the two electrode assemblies 1230 are bent relative to the connector 1221, and the electrode assembly 1230 and the connector 1221 are then placed into the housing 1210 as a whole, thus completing the assembly of the secondary battery 1200. At this time, both the positive electrode tab 120a and the negative electrode tab 120b are in a bent state.

[0053] As previously described, the electrode assembly 1230 of the secondary battery 1200 may include a positive electrode 100a and a negative electrode 100b. Specifically, the positive electrode 100a may include a positive current collector and a positive active material layer, and the negative electrode 100b may include a negative current collector and a negative active material layer. The positive active material layer is coated on a portion of the surface of the positive current collector, and the negative active material layer is coated on a portion of the surface of the negative current collector.

[0054] Taking the 1200 secondary battery as an example of a lithium-ion battery, the positive electrode current collector can be made of aluminum. The positive electrode active material layer can include positive electrode active materials, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. For high-nickel ternary lithium batteries, the positive electrode active material can be a ternary material composed of nickel, cobalt, and manganese (or aluminum). The negative electrode current collector can be made of copper. The negative electrode active material layer can include negative electrode active materials, such as carbon or silicon. The separator 200 can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0055] For ease of description, the following embodiments will be described using electrode 100. It should be noted that, unless otherwise specified, electrode 100 in the following embodiments can be either positive electrode 100a or negative electrode 100b.

[0056] In some embodiments, reference Figure 6In this embodiment, the electrode 100 may include an electrode body 110 and a plurality of tabs 120. The tabs 120 are connected to one side of the electrode body 110 along a first direction, and the plurality of tabs 120 are arranged at intervals along a second direction so that after the electrode 100 is wound, the tabs 120 can be approximately aligned. Here, the first direction is perpendicular to the second direction, and both the first and second directions are perpendicular to the thickness direction of the electrode 100. In practical applications, the first direction can be understood as the height direction of the tabs 120, and the second direction can be understood as the width direction of the tabs 120.

[0057] The electrode body 110 may include a current collector 111 and an active material layer 112 coated on opposite sides of the current collector 111. The coating area of ​​the active material layer 112 may completely cover a portion of the current collector 111 in the electrode body 110, or it may partially cover a portion of the current collector 111 in the electrode body 110. When the active material layer 112 partially covers a portion of the current collector 111 in the electrode body 110, the portion of the current collector 111 near the tab 120 is an area without the active material layer 112. Furthermore, if the thickness of the current collector 111 in this embodiment is set to d μm, then 4 ≤ d ≤ 5.5. That is, the thickness of the current collector 111 in this embodiment is reduced compared to the thickness of the current collector 111 in conventional technical solutions, which is beneficial for improving energy density.

[0058] Please refer to the above. Figure 6 and Figure 7 The tab 120 has a tab blank area 121, and a welding area 122 is provided on the side of the tab blank area 121 away from the electrode body 110. The tab 120 can be connected to the electrode through the welding area 122. Figure 5 The adapter piece 1221 is soldered. In practical applications, the entire tab 120 can be a tab blank area 121, in which case the size of the tab blank area 121 in the first direction is the same as the size of the electrode 120 in the first direction. Alternatively, the tab blank area 121 can be a portion of the tab 120, in which case the active material layer is coated on a portion of the tab 120, and the size of the tab blank area 121 in the first direction is smaller than the size of the electrode 120 in the first direction.

[0059] Specifically, the welding area 122 can be a square structure. Let the dimension of the welding area 122 in the first direction (i.e. the width of the welding area 122) be A mm, and the distance between the welding area 122 and the edge of the tab blank area 121 near the electrode body 110 in the first direction be B mm. Then A and B satisfy: 4 ≤ B / A ≤ 7.

[0060] It should be noted that when welding the tab 120 to the adapter piece 1221, multiple tabs 120 are usually pre-welded together ultrasonically first, and then a layer of tabs 120 near the adapter piece 1221 is welded to the adapter piece 1221 using laser welding. The laser welding area is located within the ultrasonic welding area, which prevents explosions during laser welding. Therefore, when using both ultrasonic welding and laser welding, the welding area 122 in this embodiment can be understood as the area where the tab 120 was ultrasonically welded. Alternatively, when welding the tab 120 to the adapter piece 1221, laser welding can also be used directly to weld the tab 120 to the adapter piece 1221. In this case, the tab 120 only has a laser welding area, and the welding area 122 in this embodiment can be understood as the area where the tab 120 was laser welded.

[0061] In this embodiment, the tab 120 can be considered as a structure formed after the current collector 111 is cut. That is, the tab 120 and the electrode body 110 are an integral structure, and the blank area 121 of the tab can be considered as the area of ​​the current collector 111 that is not coated with the active material layer 112. In this case, the thickness of the current collector 111 is the same as the thickness of the tab 120. When the thickness of the current collector 111 decreases, the thickness of the tab 120 also decreases. Alternatively, in some other embodiments, the tab 120 and the electrode body 110 can be cut separately, and then the tab 120 and the electrode body 110 are fixed by welding or other methods.

[0062] Combination Figure 2 , Figure 3 and Figure 7 The tab 120 may include a bending portion M and a welding portion N, with the bending portion M connecting the welding portion N and the tab body 110. The welding area 122 is located in the welding portion M, and the tab blank area 121, located on the side of the welding area 122 facing the tab body 110, is at least partially located in the bending portion M. When the electrode assembly 1230 and the adapter piece 1221 are integrally fixed to the housing 1210, the bending portion M of each electrode assembly 1230 can be bent relative to the tab body 110 towards the other electrode assembly 1230, so that the welding portion N can fit against the surface of the adapter piece 1221, ensuring a good welding effect between the welding area 122 and the adapter piece 1221.

[0063] It should be noted that at least a portion of the tab blank area 121 located on the side of the welding area 122 facing the tab body 110 is set in the bending portion M. This can be understood as the entire area of ​​the tab blank area 121 located on the side of the welding area 122 facing the tab body 110 being set in the bending portion M. Alternatively, it can be understood that a portion of the tab blank area 121 located on the side of the welding area 122 facing the tab body 110 is set in the welding portion M, and the other portion is set in the bending portion M. This can increase the area of ​​the welding portion N to a certain extent, so that the welding portion N can maintain a close fit with the adapter piece 1221 as much as possible, thereby ensuring the welding effect between the welding area 122 and the adapter piece 1221.

[0064] In this embodiment, by reducing the thickness of the current collector 111, the bending phenomenon of the tab 120 can be improved by reducing the overall height of the tab 120. Since the tab 120 includes a bending portion M, the size of the bending portion M and the distance B in the first direction between the welding area 122 and the edge of the tab blank area 121 near the electrode body 110 determine the size of the bending allowance space of the tab 120. Based on this, by limiting 4≤B / A≤7, the size of the welding area 122 can be guaranteed while also ensuring sufficient bending allowance space for the tab 120. When the tab 120 is in a bent state, the tension on the side of the tab blank area 121 near the electrode body 110 is small, preventing the active material layer near the tab blank area 121 from falling off. Understandably, if B / A < 4, it indicates that the width of the welding area 122 is large, resulting in a small bend allowance for the tab 120. When the tab 120 is bent, the side of the tab blank area 121 near the electrode body 110 experiences a large tensile force, causing the active material layer near the tab blank area 121 to shed material. Conversely, if B / A > 7, it indicates that the width of the welding area 122 is small, which can easily lead to poor welding results and reduced welding reliability when welding the tab 120 to the adapter piece 1221. Therefore, by limiting 4 ≤ B / A ≤ 7, reducing the height of the tab 120 to improve the bending situation not only increases welding reliability but also prevents the active material layer from shedding, thereby improving welding quality.

[0065] Furthermore, it is worth mentioning that the reduced thickness of the tab 120 leads to a decrease in the tensile force it can withstand during bending. By limiting 4 ≤ B / A ≤ 7, the welding tensile strength of the tab 120 can be improved, effectively preventing tearing of the tab 120.

[0066] In specific implementation, the B / A ratio can be, for example, 4, 4.5, 5, 5.5, 6, 6.5, 7, etc., or it can be any value between 4 and 7. This embodiment does not limit this.

[0067] As mentioned earlier, when the thickness of the current collector 111 is reduced, the tab folding phenomenon can be improved by lowering the height of the tab 120. As an optional implementation, when the thickness d of the current collector 111 is between 4 μm and 5.5 μm, the dimension of the tab 120 in the first direction (the height of the tab 120) is H mm, then H can satisfy: 10 ≤ H ≤ 35. Preferably, the height H of the tab 120 is 20 mm to 30 mm, thereby effectively solving the problem of tab folding.

[0068] In some embodiments, continue to refer to Figure 7 The tab 120 can be trapezoidal in shape, and its size gradually decreases in the direction from the electrode body 110 to the tab 120. The tab 120 may include two sides arranged along the second direction, with an angle of not more than 90° between the sides and the electrode body 110, thus reducing the risk of tearing.

[0069] Each tab's blank area 121, on the side furthest from the main body of the tab 120, is also provided with an R-angle 123 at both ends in the second direction. That is, the top two sides of the tab 120 are provided with R-angles 123. By setting the R-angles 123, the overall stiffness of the tab 120 can be improved, thereby reducing the phenomenon of the tab 120 folding.

[0070] In this embodiment, increasing the radius (R) angle 123 within a certain range helps to improve the folding phenomenon of the tab 120. However, if the radius (R) angle 123 is too large, it can easily affect the size of the welding area 122. Based on this, the minimum distance between the two radius (R) angles 123 is set to L mm, where L satisfies: 15 ≤ L ≤ 23. Here, since the side of the tab 120 furthest from the electrode body 110 has the smallest dimension in the second direction, the minimum distance between the two radius (R) angles 123 is the dimension in the second direction of the portion of the top edge of the tab 120 furthest from the electrode body 110 located between the two radius (R) angles 123.

[0071] It is understandable that if L < 15, it means the size of the R-angle 123 is small, and the improvement effect on the folding of the tab 120 is not significant. Conversely, if L > 23, it means the size of the R-angle 123 is large, and the welding area 122 needs to avoid the area where the R-angle 123 is located, resulting in a small welding area 122, which is not conducive to ensuring the welding effect. Therefore, by limiting 15 ≤ L ≤ 23, the folding of the tab 120 can be improved without affecting the welding effect, which is beneficial to improving the quality of the secondary battery 1200.

[0072] In specific implementations, L can be, for example, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, etc., or L can be any value between 15mm and 23mm. This embodiment does not limit this. As one preferred embodiment, L can be 19mm.

[0073] In some embodiments, continue to refer to Figure 7 Let the dimension of the welding area 122 in the second direction (i.e., the length of the welding area 122) be C mm. Then, C and L can satisfy the following condition: 0.91 ≤ C / L ≤ 0.98, that is, C is less than L. On the one hand, a certain gap is maintained between the welding area 122 and the R-angle 123, which increases the welding process window. When the tab 120 is welded to the adapter piece 1221, welding into the R-angle area can be avoided. On the other hand, since the tabs 120 will have a certain misalignment in the second direction after the electrode piece 100 is wound, by reserving the welding process window, welding into the R-angle area can also be avoided during welding, thereby ensuring the welding quality.

[0074] Furthermore, in this embodiment, the value is limited to 0.91 ≤ C / L ≤ 0.98. This means that if C / L < 0.91, the distance between the two radius corners 123 is large, while the length of the welding area 122 is small, resulting in a small welding area 122 and insufficient flow area. Conversely, if C / L > 0.98, the gap between the welding area 122 and the radius corners 123 is too small, making it easy to weld into the area containing the radius corners. Therefore, controlling the value to 0.91 ≤ C / L ≤ 0.98 not only ensures the flow area but also guarantees welding quality.

[0075] In specific implementation, C / L can be 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, etc., or it can be any value between 0.91 and 0.98. This embodiment does not limit it.

[0076] Furthermore, in this embodiment, A and C satisfy: 2.6 ≤ C / A ≤ 4.2. Since the welding area 122 determines the current-carrying area of ​​the secondary battery, when the width of the welding area 122 is within a certain range, the current-carrying area can be guaranteed by limiting the length of the welding area 122.

[0077] In this embodiment, if C / A < 2.6, it indicates that the length of the welding area 122 is small, and the area of ​​the welding area 122 is A*C, which easily leads to the welding area 122 being too small and unable to guarantee sufficient flow area. If C / A > 4.2, it indicates that the length of the welding area 122 is large, and the welding area 122 easily overlaps with the R-angle 123 in the second direction. When welding the tab 120 to the adapter piece 1221, it is easy to weld into the R-angle 123 area, resulting in poor welding effect. Thus, by limiting 2.6 ≤ C / A ≤ 4.2, not only can the flow area be guaranteed, but also a certain gap can be maintained between the welding area 122 and the R-angle 123 in the second direction, thereby increasing the welding process window of the tab 120.

[0078] In specific implementations, the C / A ratio can be, for example, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, etc., or the C / A ratio can be any value from 2.6 to 4.2. This embodiment does not limit this. Among them, as a preferred embodiment, the C / A ratio can be 3.2.

[0079] Furthermore, the width A of the welding area 122 can satisfy: 3mm≤A≤8mm, and correspondingly, the length B of the welding area 122 can satisfy: 20mm≤B≤35mm.

[0080] In some embodiments, reference Figures 8a to 11 The tab blank area 121 is located on the side of the welding area 122 facing the electrode body 110 and is provided with a reinforcing rib 124. The reinforcing rib 124 protrudes from the surface of the tab 120 along the thickness direction. By providing the reinforcing rib 124, the overall rigidity of the tab 120 can be enhanced, thereby effectively improving the folding of the tab 120.

[0081] In this embodiment, the reinforcing rib 124 and the tab 120 can be an integral structure, that is, the reinforcing rib 124 can be formed on the tab 120 by stamping. For example, the tab 120 can be rolled using an embossing roller to form the reinforcing rib 124 on the tab 120. Furthermore, the shape of the reinforcing rib 124 in this embodiment can be one or more of the following: dotted, striped, wavy, and zigzag shapes; that is, the reinforcing rib 124 on each tab 120 can be of one shape or a combination of multiple shapes.

[0082] As an optional implementation scheme, refer to Figure 8a and Figure 8b The reinforcing rib 124 can be dot-shaped, in which case multiple reinforcing ribs 124 can be provided in the blank area 121 of the electrode tab. For example... Figure 8a As shown, the multiple reinforcing ribs 124 can be arranged irregularly. Or, as... Figure 8bAs shown, the multiple reinforcing ribs 124 can be arranged in the form of M*N, where M is the number of reinforcing ribs 124 in the first direction and N is the number of reinforcing ribs 124 in the second direction.

[0083] As another alternative implementation scheme, refer to Figure 9a and Figure 9b The shape of the reinforcing rib 124 can be a strip. In this case, such as... Figure 9a As shown, the tab blank area 121 can be provided with a plurality of reinforcing ribs 124 spaced apart along the second direction, each reinforcing rib 124 extending along the first direction. Alternatively, as... Figure 9b As shown, the tab blank area 121 may be provided with a plurality of reinforcing ribs 124 spaced apart along the first direction, and each reinforcing rib 124 extends along the second direction.

[0084] As another alternative implementation scheme, refer to Figure 10 The reinforcing rib 124 can be wavy in shape. In this case, at least one reinforcing rib 124 extending along the second direction can be provided in the tab blank area 121. Specifically, the reinforcing rib 124 can be considered as composed of multiple sequentially connected arcs, so that the reinforcing rib 124 as a whole has a wavy structure. In this embodiment, the spacing between the two points of the reinforcing rib 124 that are farthest apart in the first direction can be designed according to actual production needs, and the number of reinforcing ribs 124 can also be designed according to the size of the reinforcing rib 124 in the first direction. When the number of reinforcing ribs 124 is greater than or equal to 2, multiple reinforcing ribs 124 can be arranged along the first direction.

[0085] As another alternative implementation scheme, refer to Figure 11 The shape of the reinforcing rib 124 can be a broken line shape. In this case, the reinforcing rib 124 may include multiple straight lines connected in sequence along the second direction, so that the reinforcing rib 124 as a whole can be regarded as being composed of multiple continuous W-shaped structures.

[0086] In some embodiments, refer again Figure 11 The portion of the tab blank area 121 located between the welding area 122 and the active material layer 112 may include a first reinforcing region S1 and a second reinforcing region S2 arranged along a first direction, wherein the second reinforcing region S2 is located between the first reinforcing region S1 and the tab body 110. A portion of the reinforcing rib 124 is located within the first reinforcing region S1, and another portion is located within the second reinforcing region S2.

[0087] In this embodiment, the depth h of the reinforcing rib 124 protruding from the surface of the tab 120 along its thickness direction is defined as the depth h of the reinforcing rib 124. Therefore, the depth h1 of the reinforcing rib 124 within the first reinforcing region S1 is greater than the depth h2 of the reinforcing rib 124 within the second reinforcing region S2. It can be understood that the greater the depth h of the reinforcing rib 124, the greater the stiffness of the tab 120, and the less likely the tab 120 is to fold. Since the first reinforcing region S1 is far from the electrode body 110, and the second reinforcing region S2 is close to the electrode body 110, the tab 120 in the first reinforcing region S1 is more prone to folding than the tab 120 in the second reinforcing region S2. Therefore, by increasing the depth h1 of the reinforcing rib 124 within the first reinforcing region S1, the structural stability of the tab 120 can be better balanced, preventing the tab 120 from folding.

[0088] Furthermore, since the second reinforcing region S2 is closer to the active material layer 112, if the depth h2 of the reinforcing rib 124 in the second reinforcing region S2 is too large, the second reinforcing region S2 will be subjected to excessive force when the reinforcing rib 124 is formed by stamping, which may easily cause the active material in the active material layer 112 near the tab 120 to fall off. Therefore, by making the depth h1 of the reinforcing rib 124 in the first reinforcing region S1 greater than the depth h2 of the reinforcing rib 124 in the second reinforcing region S2, not only can the phenomenon of tab 120 folding be better improved, but the loss of active material can also be prevented.

[0089] It should be noted that the reinforcing ribs 124 in the first reinforcing zone S1 and the second reinforcing zone S2 can be continuous or discontinuous, and this embodiment does not limit this.

[0090] Based on this, when the reinforcing rib 124 is composed of reinforcing ribs of at least two shapes, exemplarily, refer to Figure 12 The tab 120 may be provided with dot-shaped reinforcing ribs 124 and straight reinforcing ribs 124. The straight reinforcing ribs 124 may be provided in the first reinforcing region S1, and the dot-shaped reinforcing ribs 124 may be provided in the second reinforcing region S2. In this case, the reinforcing ribs 124 in the first reinforcing region S1 and the second reinforcing region S2 are discontinuous and can be formed by stamping respectively. This makes it easy to control the depth h of the reinforcing ribs 124 in the two reinforcing regions respectively.

[0091] Of course, in practical applications, when the reinforcing rib 124 is composed of at least two shapes of reinforcing rib 124, it can also be a dot-shaped reinforcing rib 124 and a wavy reinforcing rib 124, a straight reinforcing rib 124 and a wavy reinforcing rib 124, etc. Alternatively, the shape of the reinforcing rib 124 can also be a shape other than those described in the foregoing embodiments. The specific arrangement of the reinforcing rib 124 can be designed according to actual production needs, and this embodiment does not limit this.

[0092] In some embodiments, reference Figure 13 The tab 120 may also include a coating area 125, which is located between the tab blank area 121 and the electrode body 110. The coating area 125 may be coated with an active material layer. That is to say, the overall height of the tab 120 in this embodiment is the sum of the height of the coating area 125 and the height of the tab blank area 121.

[0093] In this embodiment, reference is also made to Figure 13 and Figure 14 A portion of the reinforcing rib 124 can extend from the tab blank area 121 to the coating area 125, thereby increasing the stiffness of the tab 120 by increasing the size of the reinforcing rib 124 and better preventing the tab 120 from bending. In this case, the tab 120 can also be provided with a third reinforcing area S3, located in the coating area 125. Furthermore, the depth h3 of the reinforcing rib 124 in the third reinforcing area S3 can be greater than the depth h2 of the reinforcing rib 124 in the second reinforcing area S2, but less than the depth h1 of the reinforcing rib 124 in the first reinforcing rib 124.

[0094] In this embodiment, the depth h of the reinforcing ribs 124 in the three reinforcing zones is different. The second reinforcing zone S2, with the smallest depth h, is located between the first reinforcing zone S1 and the third reinforcing zone S3, allowing the second reinforcing zone S2 to transition between the first reinforcing zone S1 and the third reinforcing zone S3. When the electrode assembly is inserted into the housing, the bending process of the tab 120 is easier, reducing the possibility of the tab 120 tearing and preventing the stress generated by bending from being transmitted to the electrode body 110, which could cause the active material layer 112 of the electrode body 110 to fall off.

[0095] It should be noted that when the reinforcing rib 124 extends from the tab blank area 121 to the coating area 125, the reinforcing rib 124 can be continuous or discontinuous. For example, the reinforcing rib 124 can be composed of dot-shaped reinforcing ribs 124 and strip-shaped reinforcing ribs 124, with the strip-shaped reinforcing ribs 124 located in the first reinforcing area S1 and the second reinforcing area S2, and the dot-shaped reinforcing ribs 124 located in the third reinforcing area S3.

[0096] In some embodiments, reference Figure 15 and Figure 16The tab blank area 121 extends to the junction where the tab 120 connects to the electrode body 110, and the active material layer 112 of the electrode body 110 is partially coated on the current collector 111. That is, the electrode body 110 includes a tab blank area 113, which is located between the active material layer 112 and the tab 120. At this time, the reinforcing rib 124 can extend from the tab blank area 121 to the tab blank area 113, thereby increasing the size of the reinforcing rib 124 in the first direction to further improve the stiffness of the tab 120, thereby better preventing the tab 120 from folding.

[0097] It should be noted that the aforementioned implementation examples Figures 6 to 16 In the illustrated scheme, all tabs 120 have the same height. In some other embodiments, reference... Figure 17 At least two tabs 120 have different heights; for example, along the second direction, the heights of each tab 120 increase or decrease sequentially. In this case, since the smaller the height of the tab 120, the less likely the tab 120 is to fold, it is only necessary to ensure that the tab 120 with the largest height satisfies the following condition: Figure 7 As shown, 4≤B / A≤7 can improve the welding effect of all 120 tabs.

[0098] In some embodiments, when the electrode 100 is a negative electrode, the current collector 111 can be a copper foil. Compared to composite current collectors with a polymer layer (e.g., PET plastic) and copper plating on both sides, although composite current collectors can achieve a very small thickness, the cost of the polymer substrate and coating material is relatively high. In this embodiment, copper is used as the material of the current collector 111, which can reduce the thickness of the current collector 111 while also reducing production costs.

[0099] The electrode sheet, secondary battery, and electronic device in this embodiment of the invention, by reducing the height of the electrode tab and limiting the width of the welding area and the blank area of ​​the electrode tab, effectively improve the electrode tab folding situation, while also increasing welding reliability and welding tensile strength. This is beneficial to improving the quality of the secondary battery, and consequently improving the reliability of the electronic device.

[0100] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this utility model without departing from the spirit and scope of this utility model. Therefore, if these modifications and variations of this utility model fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. An electrode sheet, characterized in that, It includes an electrode body and multiple electrode tabs, the electrode tabs being connected to one side of the electrode body along a first direction, and the multiple electrode tabs being arranged along a second direction, wherein the first direction is perpendicular to the second direction; The electrode body includes a current collector and an active material layer coated on opposite sides of the current collector. The thickness of the current collector is d μm, where 4 ≤ d ≤ 5.

5. The tab has a tab blank area, which includes a welding area located on the side of the tab blank area away from the electrode body for welding with the adapter piece. The welding area has a dimension of A mm in the first direction, and the distance between the welding area and the edge of the tab blank area near the electrode body in the first direction is B mm, where 4 ≤ B / A ≤ 7.

2. The electrode sheet according to claim 1, characterized in that, The electrode tab is provided with R-angles at both ends on the side away from the electrode body in the second direction, the minimum distance between the two R-angles is L mm, and the size of the welding area in the second direction is C mm, wherein 0.91≤C / L≤0.

98.

3. The electrode sheet according to claim 1, characterized in that, The condition for A and C is: 2.6 ≤ C / A ≤ 4.

2.

4. The electrode sheet according to claim 1, characterized in that, The dimension of the electrode tab in the first direction is H mm, where 10 ≤ H ≤ 35.

5. The electrode sheet according to claim 1, characterized in that, The tab blank area is provided with reinforcing ribs on the side of the welding area facing the electrode body, and the reinforcing ribs protrude from the tab along the thickness direction of the tab; The shape of the reinforcing rib is one or more of the following: dot-shaped, strip-shaped, wavy, and zigzag-shaped.

6. The electrode sheet according to claim 5, characterized in that, The electrode tab further includes a coating area located between the blank area of ​​the electrode tab and the electrode tab body, and the reinforcing rib extends from the blank area of ​​the electrode tab to the coating area; and / or The electrode body includes an electrode blank area, which is located between the active material layer and the electrode tab, and the reinforcing rib extends from the electrode tab blank area to the electrode blank area.

7. The electrode sheet according to claim 1, characterized in that, The electrode is a negative electrode, and the current collector is a copper foil.

8. The electrode sheet according to claim 1, characterized in that, Each of the electrodes has the same size in the first direction, or at least two of the electrodes have different sizes in the first direction.

9. A secondary battery, characterized in that, The device includes a housing, a top cover, and two sets of electrode assemblies disposed within the housing. Each electrode assembly includes a positive electrode, a diaphragm, and a negative electrode. The positive electrode, the diaphragm, and the negative electrode are stacked and then wound or laminated to form the electrode assembly. The negative electrode is an electrode as described in any one of claims 1-8. The top cover fits onto the housing, and the top cover has an adapter piece on the side facing the housing; The electrode assembly is located inside the housing. The tab of each negative electrode sheet includes a bending portion and a welding portion. The bending portion is connected between the welding portion and the electrode sheet body. The welding area is disposed in the welding portion. At least part of the portion between the welding area and the blank area of ​​the tab near the electrode sheet body is disposed in the bending portion. The bending portion bends relative to the electrode body toward the other electrode assembly, and the welding portion is connected to the adapter piece through the welding area.

10. An electronic device, characterized in that, Includes the secondary battery as described in claim 9.

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