Pole piece, secondary battery and electronic device

Abstract

The embodiment of the utility model provides a pole piece which comprises a composite current collector which comprises a base material layer, a first metal layer and a second metal layer, and the first metal layer and the second metal layer are arranged on the two sides of the base material layer respectively in the thickness direction of the pole piece; the pole lug is provided with a pole lug body which protrudes relative to the composite current collector in the first direction of the pole piece, in the first direction, the pole lug is provided with a fixing area at one end, facing the composite current collector, of the pole lug body, and the fixing area is connected with the first metal layer and the second metal layer; and the reinforcing ribs extend from the tab body to the fixing area. The utility model aims to provide a pole piece and a secondary battery so as to at least prevent a lug from being folded.

Description

TECHNICAL FIELD

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

[0002] Composite current collector is plated with metal layer on the surface of organic polymer film, and has good mechanical properties and electrical conductivity, when lithium ion battery adopts composite current collector, tab and composite current collector are welded, due to the soft tab, bending, wrinkle and pleat and other problems are prone to occur after die cutting. SUMMARY

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

[0004] To achieve the above object, the embodiment of the present application provides a kind of pole piece, comprising: composite current collector, including substrate layer, first metal layer and second metal layer, along the thickness direction of the pole piece, the first metal layer and the second metal layer are respectively arranged on the two sides of the substrate layer;Tab, with tab body protruding compared to the composite current collector along the first direction of the pole piece, in the first direction, the fixed area is provided at the end of the tab body towards the composite current collector, the fixed area is connected with the first metal layer and the second metal layer, reinforcing rib extends from the tab body to the fixed area.

[0005] In some embodiments, along the second direction of the pole piece, the width of the fixed area is greater than the width of the tab body, and the second direction is perpendicular to the first direction.

[0006] In some embodiments, along the second direction, the ratio of the width of the fixed area to the width of the tab body is ≥1.2.

[0007] In some embodiments, the pole piece further comprises: an active material layer covering the surface of the composite current collector, along the first direction, the active material layer is spaced apart from the fixed area.

[0008] In some embodiments, along the first direction, the ratio of the spacing distance between the active material layer and the fixed area to the size of the fixed area ranges from 0.02 to 0.8.

[0009] In some embodiments, the whole or part of the reinforcing rib is W-shaped reinforcing rib.

[0010] In some embodiments, the fixed area and the first metal layer and the second metal layer are welded to form a weld mark, and the reinforcing rib extends from the tab body to the inside of the weld mark of the fixed area.

[0011] In some embodiments, the electrode further includes an insulating layer covering the surface of the composite current collector, wherein the insulating layer is connected between the active material layer and the fixing region along the first direction.

[0012] Embodiments of this application also provide a secondary battery, including: an electrode assembly, including a stacked negative electrode, a separator, and a positive electrode, wherein the negative electrode and / or the positive electrode are the aforementioned electrodes.

[0013] In some embodiments, the electrode assembly is a wound body formed by winding the negative electrode, the diaphragm, and the positive electrode. The wound body includes a straight region and a bent region located on both sides of the straight region along a second direction of the electrode assembly. The fixing region of the tab is located in the straight region of the wound body and is spaced apart from the bent region along the second direction.

[0014] In some embodiments, the electrode assembly is a stacked body formed by stacking the negative electrode, the diaphragm, and the positive electrode, the stacked body including two opposite sides along a second direction, the diaphragm extending back and forth between the two sides to form a space that alternately accommodates the negative electrode and the positive electrode, and the fixing region of the tab is spaced apart from the edge of the electrode along the second direction.

[0015] Embodiments of this application also provide an electronic device including the aforementioned secondary battery.

[0016] The beneficial technical effects of this utility model are as follows:

[0017] The embodiments of this application extend the reinforcing rib to the fixing area. With the cooperation of the fixing area and the reinforcing rib, the electrode tab and the composite current collector can be connected into a whole under the force of the reinforcing rib, thereby strengthening the electrode tab as a whole and avoiding the formation of a weak part at the junction of the fixing area and the electrode tab body, which would cause the electrode tab to fold at the weak part. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A composite current collector and tab according to an embodiment of this application are shown.

[0020] Figure 2 The diagram shows the use of reinforcing rollers to form reinforcing ribs on the electrode lugs.

[0021] Figure 3 and Figure 4 A schematic diagram of the connection between the electrode tab and the composite current collector is shown, in which... Figure 4 It is along Figure 3 The cross-sectional view taken from line AA.

[0022] Figure 5 The die-cutting process for the electrode sheet is shown.

[0023] Figure 6 The electrode sheet after the die-cutting process according to other embodiments of this application is shown.

[0024] Figure 7 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0025] Figure 8 A partial perspective view of an electrode assembly according to an embodiment of this application is shown.

[0026] Figure 9 A cross-sectional view is shown when the electrode assembly is a stacked body.

[0027] Figure 10 It shows the corresponding Figure 9 The electrode sheet of the embodiment shown.

[0028] Figure 11 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation

[0029] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0030] 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.

[0031] 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.

[0032] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0033] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0034] When using composite current collectors for the electrode, the tabs are welded to the composite current collector. Due to the softness of the tabs, there is a high possibility that the tabs may fold over and overlap with the composite current collector when inserted into the electrode assembly. These folded tabs will subsequently be assembled into the battery along with the electrode assembly, leading to increased internal resistance. More seriously, the insertion of folded tabs into the electrode assembly can cause a short circuit between the positive and negative terminals, affecting battery safety performance.

[0035] Figures 1 to 5 The formation process of the electrode 100 according to an embodiment of this application is shown. Figure 1 The composite current collector 10 and the tab 20 according to an embodiment of this application are shown. Figure 2 The diagram shows the use of an embossing roller to roll a reinforcing rib (also known as embossing) 30 onto the tab 20. Figure 3 and Figure 4 A schematic diagram showing the connection between the tab 20 and the composite current collector 10 is provided. Figure 4 It is along Figure 3 The cross-sectional view taken from line AA. Figure 5 The illustration shows a die-cutting process (e.g., using a laser or a tool) performed on the electrode 100, wherein the fixing region 24 of the electrode tab 20 is not removed. Figure 6 In other embodiments shown, during the die-cutting process, a portion of the fixing region 24 of the tab 20 and a portion of the composite current collector 10 electrically connected to the fixing region 24 are further removed.

[0036] See Figure 5 or Figure 6 An embodiment of this application provides an electrode 100, including a composite current collector 10 and an electrode tab 20. See also Figure 4The composite current collector 10 includes a substrate layer 12 [material such as polyethylene terephthalate (PET) / polypropylene (PP) / polyethylene (PE)], a first metal layer 14, and a second metal layer 16 (e.g., a plating layer, material such as Al / Cu). Along the thickness direction T of the electrode 100, the first metal layer 14 and the second metal layer 16 are respectively disposed on both sides of the substrate layer 12. The tab 20 (e.g., a metal material) has a tab body 22 protruding from the composite current collector 10 along a first direction H of the electrode 100. In the first direction H, the tab 20 has a fixing area 24 at one end of the tab body 22 facing the composite current collector 10. The fixing area 24 is connected to the first metal layer 14 and the second metal layer 16 (e.g., welded by ultrasonic roll welding). A reinforcing rib 30 extends from the tab body 22 to the fixing area 24. The fixed area 24 is stacked and connected with the composite current collector to form a strong whole. If the reinforcing rib 30 does not extend to the fixed area 24, a weak point is easily formed at the junction of the tab body 22 and the fixed area 24, causing the tab 20 to fold at the weak point. In the embodiment of this application, the reinforcing rib 30 is extended to the fixed area 24. In this way, with the cooperation of the fixed area 24 and the reinforcing rib 30, the tab 20 and the composite current collector 10 can be connected into a whole under the force of the reinforcing rib 30, thereby strengthening the tab 20 as a whole and avoiding the formation of a weak point at the junction of the fixed area 24 and the tab body 22, which would cause the tab 14 to fold at the weak point.

[0037] It is understandable that when the fixing area 24 of the electrode tab and the composite current collector 10 are fixed by ultrasonic roll welding, although part of the structure of the reinforcing rib 30 on the fixing area 24 may be damaged, the remaining structure of the reinforcing rib 30 will still connect the electrode tab 20 and the composite current collector 10 into a whole. Generally speaking, the remaining part of the reinforcing rib 30 can be observed in the fixing area 24, and the reinforcing rib 30 extends from the electrode body 22 to the fixing area 24. There is no weak part at the junction of the electrode body 22 and the fixing area 24.

[0038] In some embodiments, the fixing region 24 is welded to the first metal layer 14 and the second metal layer 16 to form a weld mark, and the reinforcing rib 30 extends from the tab body 22 into the interior of the weld mark of the fixing region 24. The fixing region 24 is laminated and welded to the composite current collector to form a weld mark with greater hardness. Under the force of the reinforcing rib 30, the tab 20 and the composite current collector 10 are connected into a whole, thereby strengthening the tab 20 as a whole.

[0039] In some embodiments, the fixing area 24 of the tab 20 can be divided into two parts, which are respectively disposed on opposite sides of the composite current collector 10 along its thickness direction T. In this case, one part of the tab 20 overlaps the upper surface of the composite current collector 10, and the other part overlaps the lower surface of the composite current collector 10, and can be connected by ultrasonic roll welding. This allows the first metal layer 14 and the second metal layer 16 to be interconnected electrically, jointly performing the function of current transmission.

[0040] See Figure 5 or Figure 6 Along the second direction W of the electrode 100, the width of the fixing region 24 is greater than the width of the tab body 22, and the second direction W is perpendicular to the first direction H. The fixing region 24 of the tab 20 is wider than the tab body 22, providing stronger support at the base of the tab 20 and preventing the tab 20 from folding over. In some embodiments, along the second direction W of the electrode 100, the ratio of the width of the fixing region 24 to the width of the tab body 22 is ≥1.2. If the ratio of the width of the fixing region 24 to the width of the tab body 22 is too small, for example, less than 1.2, the support for the tab 20 will be insufficient.

[0041] Reference Figures 4 to 6 The electrode 100 also includes an active material layer 40, which covers the surface of the composite current collector 10. Specifically, active material layers 40 are respectively disposed on both sides along the thickness direction of the electrode 100, respectively covering the first metal layer 14 and the second metal layer 16; along the first direction H, the active material layer 40 is spaced apart from the fixing area 24. That is to say, between the fixing area 24 of the electrode tab 20 and the coating area of ​​the composite current collector 10, the composite current collector 10 also has a current collector blank area 18. Figures 1 to 5When the active material layer 40 is coated first, and then the fixing area 24 and the composite current collector 10 are fixed, the fixing area 24 and the composite current collector 10 are placed between two ultrasonic welding heads. The two ultrasonic welding heads vibrate and rub to form a weld mark. If the current collector blank area 18 is not set, the stress generated during the fixing process will be transmitted to the active material layer 40, causing the edges to easily peel off. More seriously, it may even weld directly onto the active material layer 40. When the fixing area 24 and the composite current collector 10 are fixed first, and then the active material layer 40 is coated, if the current collector blank area 18 is not set, the coating edge of the active material layer 40 will be uneven, which will lead to a decrease in the uniformity of the coating thickness at the edge of the active material layer 40. By setting the current collector blank area 18, when welding the fixing area 24 and the composite current collector 10, the stress generated during the fixing process can be avoided from affecting the edge of the active material layer 40, resulting in uneven edges. On the other hand, since the composite current collector 10 has a current collector blank area 18, the electrode 100 is not coated with an active material layer 40 in the current collector blank area 18, so the thickness is small. The current collector blank area 18 is not fixed to the electrode tab 20. Therefore, the strength of the electrode 100 at the current collector blank area 18 is low, and the electrode tab 20 may fold over as a whole from the current collector blank area 18. By keeping the width of the fixing area 24 of the electrode tab 20 wider than the electrode tab body 22 in the die-cutting process, stronger support is provided at the root of the electrode tab 20 to prevent the electrode tab 20 from folding over as a whole.

[0042] Furthermore, along the first direction H, the ratio of the distance h1 between the active material layer 40 and the fixed region 24 to the size h2 of the fixed region 24 ranges from 0.02 to 0.8. If h1 / h2 is less than 0.02, the distance h1 between the current collector blank area 18 and the fixed area 24 is too small, and the size h2 of the fixed area 24 is relatively large, resulting in excessive stress transfer when fixing the fixed area 24 and the composite current collector 10. If h1 / h2 is greater than 0.8, the current collector blank area 18 is too large, and the fixed area 24 is relatively smaller, which can easily cause the tab 20 to fold. The fixed area 24 needs to be wider to prevent the tab 20, along with its fixed area 24 and the part of the composite current collector 10 corresponding to the fixed area 24, from folding. However, the width of the fixed area 24 has an upper limit. As explained later regarding the secondary battery 1300, the fixed area 24 needs to be separated from the bending area 200 of the winding body in the prismatic battery. The fixed area 24 also needs to be separated from the lateral edge of the electrode 100 of the stacked body in the prismatic battery or pouch battery.

[0043] The reinforcing rib 30 can be a striped reinforcing rib (not shown) parallel to the first direction H. Since the reinforcing rib 30 extends from the tab body 22 to the fixing area 24, and the fixing area 24 is welded to the composite current collector 10, the part where the fixing area 24 is located has greater strength. The strength of this part and the reinforcing rib 30 can be used to strengthen the tab 20 as a whole, avoiding the formation of a weak point between the tab body 22 and the fixing area 24, which would cause the tab 20 to fold over from the weak point. Secondly, relying on the strengthening effect of the fixing area 24, the strengthened areas of multiple striped reinforcing ribs 30 can be connected to form a whole, increasing the strengthening effect on the tab 14.

[0044] When the reinforcing rib 30 is wholly or partially W-shaped, the stability of the triangle can be utilized, and the W-shaped reinforcing rib itself can be connected into a whole, which has a better reinforcing effect on the tab 20 than the striped reinforcing rib 30.

[0045] In one example, when the electrode 100 is a positive electrode, an insulating layer (also called tab adhesive) is provided on the composite current collector 10. The insulating layer covers the surface of the composite current collector 10 and is connected between the active material layer 40 and the fixing area 24 along the first direction H. By using the insulating layer to fill the blank area 18 of the current collector, the strength of the blank area 18 of the current collector is increased, and the tab 20 is prevented from bending in the blank area 18 of the current collector.

[0046] Figure 7 A perspective view of a secondary battery 1300 according to an embodiment of this application is shown. Figure 8 A partial perspective view of an electrode assembly 500 according to an embodiment of this application is shown. The secondary battery 1300 is a prismatic battery; in other embodiments, the secondary battery 1300 may also be a cylindrical battery or a pouch battery. When the secondary battery 1300 is a prismatic battery, it includes a housing 600, a cover assembly 602, and an electrode assembly 500. The housing 600 has an opening, and the cover assembly 602 includes a cover body 613 and electrode posts 611 and 612 of opposite polarity disposed on the cover body 613. The cover body 613 closes the opening and forms a receiving cavity with the housing 600. The electrode assembly 500 is disposed within the receiving cavity and includes a stacked negative electrode, a separator, and a positive electrode. The negative electrode and / or the positive electrode are electrode 100 according to an embodiment of this application.

[0047] See Figure 8When the secondary battery 1300 is a prismatic battery, the electrode assembly 500 is, for example, a wound body formed by winding a negative electrode, a separator, and a positive electrode. The wound body includes a bending region 220 and a straight region 210. The bending region 220 is located on both sides of the straight region 210 along the second direction W of the electrode assembly 500. The fixing region 24 of the tab 20 is located in the straight region 210 of the wound body and is spaced apart from the bending region 220 along the second direction W. That is, in the case of... Figures 3 to 5 In the die-cutting process shown, for the portion of the electrode 100 corresponding to the bending area 220, the fixing area 24 of the tab 20 and the portion of the composite current collector 10 sandwiched by the fixing area 24 are cut off together. This is to avoid affecting the bending and winding of the electrode 100 due to the hardness of the fixing area 24 and the composite current collector 10 after welding and fixing.

[0048] When the 1300 secondary battery is a square-shell battery or a pouch battery, such as Figure 9 As shown in the cross-sectional view, the electrode assembly 500 is a stacked body formed by stacking a negative electrode 100', a diaphragm 502 and a positive electrode 100" and the stacked body includes two opposite sides 504 along its second direction W. The diaphragm 502 extends back and forth between the two sides 504 to form a space that alternately accommodates the negative electrode 100' and the positive electrode 100".

[0049] Figure 10 It shows the corresponding Figure 9 In the embodiment shown, along the second direction W, the fixing area 24 of the tab 20 is spaced apart from the edge of the electrode 100. Especially for the negative electrode 100', the negative electrode 100' is wider than the positive electrode 100'". In the die-cutting process, the end of the fixing area 24 of the tab 24 along the second direction W is cut off to avoid puncturing due to the hardness of the fixing area 24 after it is welded and fixed to the composite current collector 10. Figure 9 The diaphragm 502 shown.

[0050] This utility model also provides an electronic device 1000. For ease of explanation, the following embodiments will use a vehicle as an example to illustrate the electronic device 1000. Figure 11This illustration shows an electronic device 1000 in an embodiment of this application when it is a vehicle. A battery pack 1002 is installed inside the vehicle, and the battery pack 1002 can be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The battery pack 1002 provides electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part is a unit component that can obtain electrical power from the battery pack 1002 and perform corresponding tasks, such as a fan blade rotation unit or a vacuum cleaner's suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0051] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An electrode sheet, characterized in that, include: A composite current collector includes a substrate layer, a first metal layer, and a second metal layer. Along the thickness direction of the electrode, the first metal layer and the second metal layer are respectively disposed on both sides of the substrate layer. The electrode has an electrode body that protrudes relative to the composite current collector along a first direction of the electrode sheet. In the first direction, the electrode body has a fixing area at one end facing the composite current collector, and the fixing area is connected to the first metal layer and the second metal layer. The reinforcing rib extends from the tab body to the fixing area.

2. The electrode sheet according to claim 1, characterized in that, Along the second direction of the electrode, the width of the fixing area is greater than the width of the electrode body, and the second direction is perpendicular to the first direction.

3. The electrode sheet according to claim 2, characterized in that, Along the second direction, the ratio of the width of the fixing region to the width of the tab body is ≥1.

2.

4. The electrode sheet according to claim 2, characterized in that, Also includes: An active material layer covers the surface of the composite current collector, and along the first direction, the active material layer is separated from the fixed area.

5. The electrode sheet according to claim 4, characterized in that, Along the first direction, the ratio of the distance between the active material layer and the fixed region to the size of the fixed region ranges from 0.02 to 0.

8.

6. The electrode sheet according to claim 1, characterized in that, The reinforcing rib is wholly or partially W-shaped.

7. The electrode sheet according to claim 1, characterized in that, The fixing area is welded to the first metal layer and the second metal layer to form a weld mark, and the reinforcing rib extends from the tab body into the interior of the weld mark of the fixing area.

8. The electrode sheet according to claim 4, characterized in that, Also includes: An insulating layer covers the surface of the composite current collector, and along the first direction, the insulating layer is connected between the active material layer and the fixing region.

9. A secondary battery, characterized in that, include: An electrode assembly includes a stacked negative electrode, a separator, and a positive electrode, wherein the negative electrode and / or the positive electrode are the electrodes as described in any one of claims 1-8.

10. The secondary battery according to claim 9, characterized in that, The electrode assembly is a wound body formed by winding the negative electrode sheet, the diaphragm and the positive electrode sheet. The wound body includes a straight region and a bent region located on both sides of the straight region along a second direction of the electrode assembly. The fixing region of the electrode tab is located in the straight region of the wound body and is spaced apart from the bent region along the second direction.

11. The secondary battery according to claim 9, characterized in that, The electrode assembly is a stacked body formed by layering the negative electrode, the separator, and the positive electrode. The stacked body includes two opposite sides along a second direction, and the separator extends back and forth between the two sides to form spaces that alternately accommodate the negative electrode and the positive electrode. Along the second direction, the fixing area of ​​the electrode tab is spaced apart from the edge of the electrode sheet.

12. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 9 to 11.

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