A secondary battery

Abstract

The utility model belongs to the technical field of energy storage equipment relates to a secondary battery, including the adapter piece and the electrode subassembly, the electrode subassembly includes two electric core units of side by side arrangement, every electric core unit includes the flat winding body and the first tab and the second tab of same polarity, the thickness direction of winding body is same with the arrangement direction of two electric core units, winding body includes respectively located the first area and the second area of winding center two sides, the first tab is connected in the first area, the second area includes the outer area and the inner area of winding center of winding body relative to the outer area more close, the second tab is connected in the outer area, the first tab and the second tab of two electric core units in electrode subassembly are all connected with same adapter piece, the utility model is favorable for reducing the resistance between the part of pole piece and the adapter piece of winding body outer circle, and then reduces the heat production of electric core unit in the use process.

Description

Technical Field

[0001] This utility model relates to the field of energy storage equipment technology, and in particular to a secondary battery. Background Technology

[0002] Secondary batteries, such as lithium-ion batteries, typically consist of a casing and battery cells housed within it. Due to limitations in electrode welding processes, for battery cells using a winding process, the electrode layer on one side of the winding center usually has electrodes extending from the winding body. The winding body is connected to structures such as adapter plates via these electrodes. As the spacing between adjacent electrodes gradually increases from the winding center towards the outer layers of the winding body, this increases the resistance between the portion of the electrode on the outer edge of the winding body and the adapter plates. Consequently, the overall resistance of the battery cell increases. With the same output current, this increases heat generation during use and reduces the energy conversion efficiency of the secondary battery. Summary of the Invention

[0003] This invention provides a secondary battery to solve the technical problems of high cell unit resistance and low energy conversion efficiency in secondary batteries.

[0004] This utility model provides a secondary battery, including an adapter plate and an electrode assembly. The electrode assembly includes two cell units arranged side by side. Each cell unit includes a flat wound body and a first tab and a second tab with the same polarity. The thickness direction of the wound body is the same as the arrangement direction of the two cell units. Along the thickness direction of the wound body, the wound body includes a first region and a second region located on both sides of the winding center, and the first electrode tab is connected to the first region; Along the thickness direction of the wound body, the second region includes an outer layer region and an inner layer region that is closer to the winding center of the wound body than the outer layer region, and the second electrode tab is connected to the outer layer region; The first tab and the second tab of the two battery cells in the electrode assembly are both connected to the same adapter plate. The first regions of the winding bodies in the two battery cells in the electrode assembly are close to each other, and the second regions of the winding bodies in the two adjacent battery cells are far apart from each other.

[0005] In one embodiment of the present invention, the arrangement direction of the two battery cells in the electrode assembly is a first direction. Along the first direction, in the battery cell adjacent to the wall of the secondary battery casing, the outer layer region is closer to the wall of the casing than the inner layer region.

[0006] In one embodiment of the present invention, the secondary battery includes two electrode assemblies, which are arranged side by side along the first direction and are adjacent to the walls of two shells of the secondary battery that are opposite to each other along the first direction.

[0007] In one embodiment of the present invention, both the first electrode tab and the second electrode tab are trapezoidal structures, and the bottom edge of both the first electrode tab and the second electrode tab are connected to the winding body. The angle between the waistline of the first electrode tab and the bottom edge is θ2, and the angle between the waistline of the second electrode tab adjacent to the wall of the housing in the electrode assembly and the bottom edge is θ1, where θ1 > θ2.

[0008] In one embodiment of the present invention, both the first electrode tab and the second electrode tab are trapezoidal structures, and the bottom edge of both the first electrode tab and the second electrode tab are connected to the winding body. The angle between the waistline of the first electrode tab and the bottom edge is θ2, and the angle between the waistline of the second electrode tab in the electrode assembly away from the wall of the housing and the bottom edge is θ3, where θ2 > θ3.

[0009] In one embodiment of the present invention, the winding body includes a plurality of electrode layers stacked along the thickness direction of the winding body, the first electrode tab is connected to at least a portion of the electrode layers in the first region, and the second electrode tab is connected to at least a portion of the electrode layers in the outer region. The number of the first electrode tabs is m, the number of the second electrode tabs is n, and 0.25≤n / m≤0.75.

[0010] In one embodiment of the present invention, each of the second tabs is connected to each of the electrode layers in the outer layer region in a one-to-one correspondence.

[0011] In one embodiment of the present invention, the electrode layer of the outer region includes a first electrode layer connected to the second electrode tab and a second electrode layer not connected to the second electrode tab, and the first electrode layer and the second electrode layer are alternately arranged along the thickness direction of the winding body.

[0012] In one embodiment of this utility model, n / m = 0.5.

[0013] In one embodiment of the present invention, the width of the first electrode tab connected to one end of the winding body is w1, and the width of the second electrode tab connected to one end of the winding body is w2, where w1 < w2.

[0014] The beneficial effects of this utility model are as follows: The secondary battery proposed in this utility model connects tabs to the first and second regions on both sides of the winding center of the winding body, and the tabs connected to the second region are connected to the outer layer region of the second region. The outer layer region is closer to the outer ring of the winding body, which reduces the spacing between the tabs of the electrode sheets located on the outer ring of the winding body. This helps to reduce the resistance between the electrode sheets located on the outer ring of the winding body and the adapter plate, thereby reducing the heat generation of the cell unit during use and improving the energy conversion efficiency of the secondary battery during use. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0016] In the attached diagram: Figure 1 This is a schematic diagram of the battery cell unit provided in this embodiment; Figure 2 This is a schematic diagram of the electrode assembly provided in this embodiment; Figure 3 This is a schematic diagram of the structure of the secondary battery provided in this embodiment; Figure 4 This is a schematic diagram of the structure of the first electrode and the second electrode provided in this embodiment.

[0017] The attached figures are labeled as follows: 1. First electrode tab 2. Second electrode tab 3. Adapter plate 4. Winding body 5. Battery cell unit 6. Electrode assembly 7. Wall 8. First region 9. Second region 10. Inner layer region 11. Outer layer region 12. First direction T. Detailed Implementation

[0018] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0019] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0020] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0021] Please see Figures 1-3 This embodiment provides a secondary battery, including an adapter 3 and an electrode assembly 6. The electrode assembly 6 includes two battery cell units 5 arranged side by side, such as... Figure 1 As shown, each battery cell unit 5 includes a first tab 1, a second tab 2, and a flat wound body 4. In the electrode assembly 6, the side-by-side direction of the two battery cell units 5 is the first direction T, and the thickness direction of the wound body 4 is set along the first direction T, that is, the thickness direction of the wound body 4 is the same as the first direction T. The wound body 4 is the main structure of the battery cell unit 5, and its thickness direction is also the thickness direction of the battery cell unit 5. In this embodiment, the secondary battery is a lithium-ion battery. The first tab 1 and the second tab 2 have the same polarity. The first tab 1 and the second tab 2 can both be positive tabs or both be negative tabs. It can be understood that when the first tab 1 and the second tab 2 are positive tabs, the battery cell unit 5 also includes a negative tab, and when the first tab 1 and the second tab 2 are negative tabs, the battery cell unit 5 also includes a positive tab.

[0022] Along the thickness direction of the wound body 4, the wound body 4 includes a first region 8 and a second region 9, which are located on both sides of the winding center of the wound body 4. A first electrode tab 1 is connected to the first region 8. In this embodiment, the first electrode tab 1 extends from the electrode sheet of the wound body 4 located in the first region 8.

[0023] Along the thickness direction of the winding body 4, the second region 9 includes an outer layer region 11 and an inner layer region 10. The inner layer region 10 is closer to the winding center of the winding body 4 than the outer layer region 11. The second tab 2 is connected to the outer layer region 11, and the first tab 1 and the second tab 2 of the two battery cells 5 in the electrode assembly 6 are both connected to the same adapter piece 3.

[0024] In this embodiment, in the thickness direction of the winding body 4, the outer layer region 11 is closer to the outside of the winding body 4 than the inner layer region 10, and the inner layer region 10 is closer to the inside of the winding body 4 than the outer layer region 11. The first tab 1 extends from the electrode sheet of the winding body 4 located in the outer layer region 11. The outer layer region 11 is closer to the outer ring of the winding body 4, which reduces the spacing along the length of the electrode sheet between the tabs of the portion of the electrode sheet located in the outer ring of the winding body 4. This helps to reduce the resistance between the portion of the electrode sheet located in the outer ring of the winding body 4 and the adapter plate 3, thereby reducing the heat generation of the cell unit 5 during use and improving the energy conversion efficiency of the secondary battery during use.

[0025] Meanwhile, in this embodiment, the first regions 8 of the winding bodies 4 in the two battery cells 5 of the electrode assembly 6 are close to each other, while the second regions 9 of the winding bodies 4 in the two adjacent battery cells 5 are far apart. Because the first regions 8 of the two battery cells 5 in the electrode assembly 6 are close to each other, the first tabs 1 of the two battery cells 5 in the electrode assembly 6 are also close to each other and located in the middle region along the thickness direction of the winding body 4 of the electrode assembly 6. The large number of first tabs 1 and their location in the middle region of the electrode assembly 6 facilitates heat dissipation from the middle region of the electrode assembly 6 to the outside through the first tabs 1, increasing the overall heat dissipation capacity of the electrode assembly 6.

[0026] In one embodiment, along the first direction T, that is, along the arrangement direction of the two cell units 5 in the electrode assembly 6, the outer layer region 11 of the two cell units 5 adjacent to the wall portion 7 of the secondary battery casing in the electrode assembly 6 is closer to the casing wall portion 7 than its inner layer region 10. The proximity of the outer layer region 11 to the casing wall portion 7 means that the second tab 2 connected to the outer layer region 11 is also closer to the casing wall portion 7, which facilitates the conduction of heat generated by the second tab 2 to the outside of the casing through the casing wall portion 7, thereby improving the heat dissipation capacity of the second tab 2.

[0027] like Figure 2 As shown, specifically in one embodiment, the secondary battery includes two electrode assemblies 6 arranged side-by-side along a first direction T, that is, the side-by-side direction of the two electrode assemblies 6 is the same as the arrangement direction of the two cell units 5 in the electrode assembly 6. Each of the two electrode assemblies 6 is connected to a corresponding adapter piece 3. The casing of the secondary battery has two opposing walls 7 along the first direction T, and the two electrode assemblies 6 are adjacent to the two walls 7 respectively, that is, one electrode assembly 6 is close to one wall 7, and the other electrode assembly 6 is close to the other wall 7. The two electrode assemblies 6 can dissipate heat to the outside of the casing through their respective walls 7, which is beneficial to improving the heat dissipation effect of the electrode assemblies 6.

[0028] like Figure 4As shown, in one embodiment, both the first tab 1 and the second tab 2 are trapezoidal, and the bottom edges of both the first tab 1 and the second tab 2 are connected to the winding body 4. In the two cell units 5 of the electrode assembly 6, the second tab 2 of one cell unit 5 is adjacent to the wall 7 of the housing, while the second tab 2 of the other cell unit 5 is relatively far from the wall 7 of the housing. In the electrode assembly 6, the angle between the waistline and the bottom edge of the second tab 2 of the cell unit 5 adjacent to the wall 7 of the housing is θ1, while the angle between the waistline and the bottom edge of the first tab 1 is θ2, where θ1 > θ2. Since θ1 > θ2, under the same conditions, it is advantageous to increase the cross-sectional area of ​​the second tab 2, thereby helping to reduce the resistance of the second tab 2.

[0029] In another embodiment, both the first tab 1 and the second tab 2 are trapezoids whose bottom edges are connected to the winding body 4. The angle between the waistline of the first tab 1 and its bottom edge is θ2, and the angle between the waistline of the second tab 2 in the electrode assembly 6, which is away from the wall 7 of the housing, and its bottom edge is θ3, where θ2 > θ3. The second tab 2 in the electrode assembly 6, which is away from the wall 7 of the housing, is close to the wall 7 of the housing, and its heat dissipation effect is better. Since θ2 > θ3, under the same conditions, the size of the second tab 2 in the electrode assembly 6, which is away from the wall 7 of the housing, can be reduced, thereby helping to improve the energy density of the cell unit 5.

[0030] like Figures 1-4 As shown, specifically, in this embodiment, both the first tab 1 and the second tab 2 are trapezoids whose bottom edges are connected to the winding body 4. The angle between the waistline of the second tab 2 of the cell unit 5 adjacent to the wall portion 7 of the housing and the bottom edge is θ1, the angle between the waistline of the first tab 1 and the bottom edge is θ2, and the angle between the waistline of the second tab 2 of the electrode assembly 6 away from the wall portion 7 of the housing and the bottom edge is θ3, where θ1 > θ2 > θ3.

[0031] In one embodiment, the width of the first tab 1 connected to one end of the winding body 4 is w1, and the width of the second tab 2 connected to one end of the winding body 4 is w2, where w1 < w2. In the electrode assembly 6, the second tab 2 is closer to the outer layer of the winding body 4 than the first tab 1. Therefore, the spacing between adjacent tabs on the outer layer of the winding body 4 along the length of the electrode is larger. Thus, under the same conditions, the larger width of the second tab 2 connected to one end of the winding body 4 is beneficial for increasing the cross-sectional area of ​​the second tab 2, reducing the resistance of the second tab 2, thereby reducing the heat generation of the cell unit 5 during use, and improving the energy conversion efficiency of the secondary battery during use.

[0032] In some embodiments, the outer electrode layer includes a first electrode layer connected to the second tab 2 and a second electrode layer not connected to the second tab 2, with the first and second electrode layers alternately arranged along the thickness direction of the winding body 4. The absence of second tabs in a portion of the outer electrode layer helps reduce the overall number of second tabs 2, thereby reducing the weight of the battery cell and increasing the energy density per unit weight of the secondary battery. The alternating arrangement of the first and second electrode layers along the thickness direction of the winding body 4 ensures a more uniform distribution of the second tabs 2 on the portion of the electrode located on the outer ring of the winding body 4.

[0033] In one embodiment, the wound body 4 includes multiple electrode layers stacked along the thickness direction of the wound body 4. First electrode tabs 1 are connected one-to-one with at least a portion of the electrode layers in the first region 8, and second electrode tabs 2 are connected one-to-one with at least a portion of the electrode layers in the outer region 11. The number of first electrode tabs 1 is m, and the number of second electrode tabs 2 is n, where m > n. Heat from the electrode assembly 6 can be conducted outwards through the electrode tabs. Since m > n, the number of first electrode tabs 1 is greater than the number of second electrode tabs 2. This results in a larger number of electrodes located in the middle of the electrode assembly 6 along the arrangement direction of the two battery cells 5, which helps increase the thermal conductivity in the middle of the electrode assembly 6 and thus improves the overall heat dissipation effect of the electrode assembly 6.

[0034] In this embodiment, 0.25 ≤ n / m ≤ 0.75. The number of first tabs 1 is usually kept constant, while the number of second tabs 2 is adjusted according to the actual situation of the secondary battery. Increasing the number of second tabs 2 helps to reduce the resistance between the portion of the electrode located on the outer ring of the winding body 4 and the adapter piece 3. Decreasing the number of second tabs 2 helps to reduce the weight of the secondary battery and increase the energy density per unit weight of the secondary battery. Specifically, in this embodiment, n / m = 0.5.

[0035] The beneficial effects of this utility model are as follows: The secondary battery proposed in this utility model connects tabs to the first and second regions on both sides of the winding center of the winding body, and the tabs connected to the second region are connected to the outer layer of the second region. This reduces the spacing between the tabs of the portion of the electrode sheet located on the outer ring of the winding body, which helps to reduce the resistance between the portion of the electrode sheet located on the outer ring of the winding body and the adapter plate. This, in turn, reduces the heat generated by the cell unit during use and improves the energy conversion efficiency of the secondary battery during use.

[0036] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A secondary battery, characterized in that, The device includes an adapter plate and an electrode assembly. The electrode assembly includes two battery cells arranged side by side. Each battery cell includes a flat winding body and a first electrode and a second electrode with the same polarity. The thickness direction of the winding body is the same as the arrangement direction of the two battery cells. Along the thickness direction of the wound body, the wound body includes a first region and a second region located on both sides of the winding center, and the first electrode tab is connected to the first region; Along the thickness direction of the wound body, the second region includes an outer layer region and an inner layer region that is closer to the winding center of the wound body than the outer layer region, and the second electrode tab is connected to the outer layer region; The first tab and the second tab of the two battery cells in the electrode assembly are both connected to the same adapter plate. The first regions of the winding bodies in the two battery cells in the electrode assembly are close to each other, and the second regions of the winding bodies in the two adjacent battery cells are far apart from each other.

2. The secondary battery according to claim 1, characterized in that, The arrangement direction of the two cell units in the electrode assembly is a first direction. Along the first direction, in the cell unit adjacent to the wall of the secondary battery casing, the outer layer region is closer to the wall of the casing than the inner layer region.

3. The secondary battery according to claim 2, characterized in that, The secondary battery includes two electrode assemblies, which are arranged side by side along the first direction and are adjacent to the walls of two shells of the secondary battery that are opposite each other along the first direction.

4. The secondary battery according to claim 3, characterized in that, Both the first electrode tab and the second electrode tab are trapezoidal structures, and the bottom edge of the first electrode tab and the bottom edge of the second electrode tab are connected to the winding body. The angle between the waistline of the first electrode tab and the bottom edge is θ2. The angle between the waistline of the second electrode tab adjacent to the wall of the housing in the electrode assembly and the bottom edge is θ1, where θ1 > θ2.

5. The secondary battery according to claim 3, characterized in that, Both the first electrode tab and the second electrode tab are trapezoidal structures, and the bottom edge of the first electrode tab and the bottom edge of the second electrode tab are connected to the winding body. The angle between the waistline of the first electrode tab and the bottom edge is θ2, and the angle between the waistline of the second electrode tab in the electrode assembly away from the wall of the housing and the bottom edge is θ3, where θ2 > θ3.

6. The secondary battery according to claim 1, characterized in that, The winding body includes multiple electrode layers stacked along the thickness direction of the winding body. The first electrode tab is connected to at least a portion of the electrode layers in the first region, and the second electrode tab is connected to at least a portion of the electrode layers in the outer region. The number of the first electrode tabs is m, and the number of the second electrode tabs is n, where 0.25 ≤ n / m ≤ 0.

75.

7. The secondary battery according to claim 6, characterized in that, Each of the second tabs is connected to each of the electrode layers in the outer layer region in a one-to-one correspondence.

8. The secondary battery according to claim 6, characterized in that, The outer layer region includes a first electrode layer connected to the second electrode tab and a second electrode layer not connected to the second electrode tab. The first electrode layer and the second electrode layer are alternately arranged along the thickness direction of the winding body.

9. The secondary battery according to claim 6, characterized in that, n / m=0.

5.

10. The secondary battery according to any one of claims 1 to 9, characterized in that, The width of the first tab connected to one end of the winding body is w1, and the width of the second tab connected to one end of the winding body is w2, where w1 < w2.

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