Laminated multi-tab battery cell, lithium battery and vehicle

Abstract

According to the laminated multi-tab battery cell, the lithium battery and the vehicle provided by the embodiment of the invention, the heights of the positive electrode tab and the negative electrode tab are respectively and symmetrically arranged according to the lamination direction, so that the calculation amount of the tab sizes is reduced, all the tab sizes can be obtained only by calculating half of the tab size, subsequent assembly and positioning are facilitated, the production efficiency is improved, and the production cost is reduced. The reject ratio in the production process is reduced; and the structural design enables the internal structure of the battery to be more balanced, deformation caused by uneven stress is reduced when the charging and discharging volume changes, and the stability and safety of the battery structure are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field related to batteries, and in particular, relates to a stacked multi-tab battery cell, a lithium battery, and a vehicle. Background Art

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] With the rapid development of new energy vehicles and the energy storage field, the iteration speed of lithium battery products is getting faster and faster. To meet the performance requirements such as ultra-fast charging, ultra-long endurance, and high energy, the number of layers of battery electrode sheets and the number of winding turns are increasing. Whether it is the stacking or winding process, the increase in the number of electrode sheet layers or winding turns has a certain impact on the welding yield of the tabs. If the tab size is not designed reasonably, in the ultrasonic welding or laser welding process of the tabs, since the positioning fixture fixes the tabs, it is extremely easy to cause tearing and fracture at the root of the tabs, affecting the current-carrying capacity of the battery. In addition, in some application scenarios of the battery, due to external vibrations, jitters, etc., if the tab size is unreasonable, tearing and fracture phenomena will also occur, and metal chips have been generated at the fracture, which is likely to cause a short circuit of the battery. The above two phenomena seriously threaten the product quality and safety. Therefore, a reasonable tab size design is particularly important.

[0004] In the prior art, CN118720442A proposes a tab gradient design and gives a relatively accurate calculation formula. However, in this patent, the size of each tab needs to be calculated, and the more tabs are designed, the greater the calculation amount. CN117832647A proposes a multi-tab staggered winding method to improve the tab alignment and welding defects. However, the calculation of the tab spacing size in this patent is not accurate enough. If the electrode sheet thickness or tab die-cutting fluctuates, the tabs are likely to be misaligned after winding. When the tabs are misaligned to form an overlapping area, the number of overlapping tab layers is too many, resulting in uneven surfaces of the tabs, and the pressing cannot be flat on the tab surface, which has a great impact on the yield of the laser welding process. Therefore, this process method has strict requirements for the consistency of the electrode sheet manufacturing process. If there are defects, the entire electrode sheet will be scrapped, and the manufacturing cost is relatively high. Summary of the Invention

[0005] To overcome the above-mentioned deficiencies of the prior art, the present invention provides a stacked multi-tab battery cell, a lithium battery, and a vehicle, which reduces the calculation amount of the tab size, makes the internal structure of the battery more balanced, reduces the deformation caused by uneven stress during the charge and discharge volume change, and enhances the structural stability and safety of the battery.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a stacked multi-tab battery cell, comprising: a plurality of positive electrode sheets, a plurality of negative electrode sheets and a plurality of separator layers. The positive electrode sheets and the negative electrode sheets are alternately stacked, and the separator layers are disposed between the positive electrode sheets and the negative electrode sheets. The positive electrode sheets and the negative electrode sheets are respectively provided with positive tabs and negative tabs. In the stacking direction, the heights of the positive tabs and the negative tabs are symmetrically arranged respectively.

[0008] Preferably, the plurality of positive tabs and the plurality of negative tabs are stacked in a staggered manner.

[0009] Preferably, the distance from the left side of the negative tab and the positive tab corresponding to an odd number to the left side of the corresponding negative electrode sheet and positive electrode sheet is equal to the distance from the right side of the negative tab and the positive tab corresponding to an even number to the right side of the corresponding negative electrode sheet and positive electrode sheet.

[0010] The distance from the right side of the negative tab and the positive tab corresponding to an odd number to the right side of the corresponding negative electrode sheet and positive electrode sheet is equal to the distance from the left side of the negative tab and the positive tab corresponding to an even number to the left side of the corresponding negative electrode sheet and positive electrode sheet.

[0011] Preferably, there are (2n + 4) positive electrode sheets and (2n + 5) negative electrode sheets, where n is an integer not less than 1. Then the heights of the (2n - 1)th negative tab and the (2n)th positive tab are respectively the sum of the width of the pre-welding mark of the tab and the distance from the bottom of the mark to the top of the tab side of the battery cell.

[0012] Preferably, in the stacking direction, with the (2n - 1)th negative tab as the center, the heights of the negative tabs on both sides of the center are symmetrically arranged.

[0013] Preferably, in the stacking direction, with the (2n)th positive tab as the center, the heights of the positive tabs on both sides of the center are symmetrically arranged.

[0014] Preferably, both the positive tabs and the negative tabs are trapezoidal structures.

[0015] Preferably, the number of separator layers is twice the number of negative electrode sheets.

[0016] In a second aspect, the present invention provides a lithium battery, comprising the above-mentioned stacked multi-tab battery cell.

[0017] In a third aspect, the present invention provides a vehicle, which uses the above-mentioned lithium battery.

[0018] The above one or more technical solutions have the following beneficial effects:

[0019] In the present invention, in the stacking direction, the heights of the positive electrode tab and the negative electrode tab are symmetrically arranged respectively, reducing the calculation amount of the tab size. Only half of the tab size needs to be calculated to obtain all the tab sizes. Moreover, the current-carrying area of the tab is increased, thereby improving the current-carrying capacity of the battery cell, enhancing the fast charging efficiency, and reducing the temperature rise of the battery cell, etc. In addition, this structural design makes the internal structure of the battery more balanced. When the volume changes during charging and discharging, the deformation caused by uneven stress is reduced, enhancing the structural stability and safety of the battery.

[0020] Advantages of additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The schematic diagrams in the specification forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0022] Figure 1 It is a schematic diagram of the design of the laminated multi-layer tab size in the embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the calculation of the height gradient of the negative electrode tab in the embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the calculation of the height gradient of the positive electrode tab in the embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of the design of the staggered stacking and cutting of the laminated multi-layer tabs in the embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram after pre-welding of the tabs in the embodiment of the present invention Figure 1 ;

[0027] Figure 6 It is a schematic diagram after pre-welding of the tabs in the embodiment of the present invention Figure 2 ;

[0028] In the figure, 10, tab; 20, electrode plate; 30, electrode plate cutting position; 40, separator; 50, positive electrode plate; 501, positive electrode upper coating layer; 502, aluminum foil; 503, positive electrode lower coating layer; 60, negative electrode plate; 601, negative electrode upper coating layer; 602, copper foil; 603, negative electrode lower coating layer; 70, tab welding area; 80, battery housing; 90, tab after ultrasonic welding. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0030] It should be noted that the terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0031] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0032] This embodiment discloses a stacked multi-tab battery cell, including: a plurality of positive electrode sheets, a plurality of negative electrode sheets, and multiple layers of separators. The positive electrode sheets and the negative electrode sheets are alternately stacked, and the separators are disposed between the positive electrode sheets and the negative electrode sheets; the positive electrode sheets and the negative electrode sheets are respectively provided with positive electrode tabs and the negative electrode tabs; in the stacking direction, the heights of the positive electrode tabs and the negative electrode tabs are symmetrically arranged respectively.

[0033] As a possible implementation manner, a plurality of the positive electrode tabs and a plurality of the negative electrode tabs are all staggeredly stacked and arranged.

[0034] As a possible implementation manner, for the negative electrode tabs and the positive electrode tabs corresponding to odd numbers, the distances from the left sides of the negative electrode tabs and the positive electrode tabs to the left sides of the corresponding negative electrode sheets and positive electrode sheets are equal to the distances from the right sides of the negative electrode tabs and the positive electrode tabs corresponding to even numbers to the right sides of the corresponding negative electrode sheets and positive electrode sheets;

[0035] For the negative electrode tabs and the positive electrode tabs corresponding to odd numbers, the distances from the right sides of the negative electrode tabs and the positive electrode tabs to the right sides of the corresponding negative electrode sheets and positive electrode sheets are equal to the distances from the left sides of the negative electrode tabs and the positive electrode tabs corresponding to even numbers to the left sides of the corresponding negative electrode sheets and positive electrode sheets.

[0036] As a possible implementation manner, there are (2n + 4) positive electrode sheets and (2n + 5) negative electrode sheets; where n is an integer not less than 1; then the heights of the (2n - 1)-th negative electrode tab and the (2n)-th positive electrode tab are respectively the sum of the width of the pre-welding imprint of the tab and the distance from the bottom of the imprint to the top of the side of the battery cell tab.

[0037] As a possible implementation manner, in the stacking direction, with the (2n - 1)-th negative electrode tab as the center, the heights of the negative electrode tabs on both sides of the center are symmetrically arranged.

[0038] As a possible implementation manner, in the stacking direction, with the (2n)-th positive electrode tab as the center, the heights of the positive electrode tabs on both sides of the center are symmetrically arranged.

[0039] As a possible implementation, both the positive electrode tab and the negative electrode tab are trapezoidal structures.

[0040] As Figure 1 shown, it is a schematic diagram of the laminated multi-tab size design provided by this embodiment. The positive and negative electrode coils pass through a laser die-cutting machine, and the tabs 10 are regularly cut into trapezoids. Denote the height of the first tab (E1) as H1, the height of the second tab (E2) as H2, and so on. The height of the 2nth tab (E 2n ) is H 2n , and the height of the (2n + 1)th tab (E 2n+1 ) is H 2n+1 . The appearance dimensions of the positive and negative electrodes are the same.

[0041] As Figure 2 shown, due to the internal structure of the battery cell, the total number of negative electrode sheets 60 is generally odd, the total number of positive electrode sheets 50 is generally even, and the number of layers of the separator 40 is twice the number of layers of the negative electrode sheet 50. The negative electrode sheet 60 includes a negative electrode upper coating layer 601, a copper foil 602, and a negative electrode lower coating layer 603; the positive electrode sheet 50 includes a positive electrode upper coating layer 501, an aluminum foil 502, and a positive electrode lower coating layer 503.

[0042] Assume that the number of layers of the positive electrode sheet of the battery cell is (2n + 4), then the number of negative electrode layers is (2n + 5), where n ≥ 1; the width of the pre-welding mark in the tab welding area 70 is W; after the tabs are pre-welded, the distance from the bottom end of the welding mark to the top of the battery cell tab side is denoted as D, and the height of a certain negative electrode tab in the middle of the negative electrode is D + W. Assume that the middle negative electrode sheet is the E 2n-1 th sheet, then the height H 2n-1 of its negative electrode tab = D + W.

[0043] Given the thickness T1 of the positive electrode sheet, the thickness T2 of the negative electrode sheet, and the thickness T3 of the separator, the height of the upper and lower adjacent negative electrode tabs can be obtained, that is:

[0044] …

[0045]

[0046] H 2n-1 = D + W;

[0047]

[0048]

[0049] …

[0050] From the above formula, it is obtained that H 2n+1 = H 2n-3 , H 2n+3 = H 2n-5 H2n+3 = H 2n-7 Taking the (2n - 1)-th layer negative electrode sheet as the center and being symmetrical in the stacking direction, in this embodiment, the total ear gradient size can be obtained by calculating only the ear height above or below the (2n - 1)-th layer. Among them, H 2n-4 , H 2n-2 , H 2n , H 2n+2 , H 2n+4 etc. represent the height of the positive electrode ears; H 2n-5 , H 2n-3 , H 2n-1 , H 2n+3 , H 2n+5 etc. represent the height of the negative electrode ears.

[0051] If one layer of positive electrode sheet, one layer of negative electrode sheet and two layers of separator are regarded as a unit, then the thickness T of a unit is T = T1 + T2 + 2T3, and the ear height of the negative electrode sheet can be simplified as: N is a positive integer. For example: That is At this time, N = 1.

[0052] Calculation of the positive electrode ear gradient size, as Figure 3 shown, similarly, H 2n = D + W, that is: N is a positive integer.

[0053] After the ear size is designed, to improve the current-carrying capacity and welding yield of the ears, in this embodiment, the pole roll is cut according to a certain rule to obtain the required electrode sheets for stacking, as Figure 4 shown. The distance from the left side of the ears of the odd-numbered sheets of the positive and negative electrodes to the left side of the corresponding electrode sheets is L1, and the distance from the right side of the ears of the odd-numbered sheets of the positive and negative electrodes to the right side of the corresponding electrode sheets is L2; the distance from the left side of the ears of the even-numbered sheets of the positive and negative electrodes to the left side of the corresponding electrode sheets is L3, L3 = L2, and the distance from the right side of the ears of the even-numbered sheets of the positive and negative electrodes to the right side of the corresponding electrode sheets L4 = L1; L5 is the total length of the positive and negative electrode sheets; stack the electrode sheets according to this size; after stacking, ultrasonic welding is used to preliminarily shape the ears. The positional relationship between the ears 90 and the battery case 80 after ultrasonic welding is as Figure 5 and Figure 6 shown.

[0054] In this embodiment, 1 electrode sheet has 1 ear, that is, the number of positive / negative electrode ears is equal to the number of positive / negative electrode sheets. Therefore, the total number of ears is equal to the number of positive electrode sheets + the number of negative electrode sheets. Thus, the total number of ears is (4n + 9), where n ≥ 1.

[0055] It should be noted that the above description of left and right is based on the stacking direction.

[0056] In this embodiment, by designing the gradient mirror of the tab, only half of the tab size needs to be calculated to obtain all the tab sizes; after welding, the root of the tab is in a "trapezoidal" structure, and the shape change of the tab root is milder; the redundant part at the tab root is not easily inserted into the electrode plate, improving the safety of the battery cell. The tabs are stacked in a staggered manner, solving the problems of ultra-thick multi-layer tabs and low welding yield; the tabs are stacked in a staggered manner to form double tabs, which improves the current-carrying capacity compared with single tabs.

[0057] This embodiment also provides a lithium battery, including the above-mentioned stacked multi-tab battery cell.

[0058] This embodiment also provides a vehicle using the above-mentioned lithium battery.

[0059] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A laminated multi-electrode battery cell, comprising: A plurality of positive electrode sheets, a plurality of negative electrode sheets and a multilayer separator, wherein the positive electrode sheets and the negative electrode sheets are alternately stacked, and the separator is arranged between the positive electrode sheets and the negative electrode sheets; the positive electrode sheets and the negative electrode sheets are respectively provided with a positive electrode tab and a negative electrode tab; it is characterized in that, according to the stacking direction, the heights of the positive electrode tab and the negative electrode tab are respectively arranged symmetrically.

2. A laminated multi-electrode battery cell as claimed in claim 1, characterized in that: The plurality of positive electrode tabs and the plurality of negative electrode tabs are stacked and arranged in a staggered manner.

3. A laminated multi-electrode battery cell as claimed in claim 1, characterized in that: The distances from the left side of the negative electrode tab and the positive electrode tab corresponding to the odd numbers to the corresponding negative electrode sheet and the left side of the positive electrode sheet are equal to the distances from the right side of the negative electrode tab and the positive electrode tab corresponding to the even numbers to the corresponding right side of the negative electrode sheet and the positive electrode sheet; The distance from the right side of the negative electrode tab and the positive electrode tab corresponding to the odd numbers to the corresponding negative electrode sheet and the right side of the positive electrode sheet is equal to the distance from the left side of the negative electrode tab and the positive electrode tab corresponding to the even numbers to the corresponding negative electrode sheet and the left side of the positive electrode sheet.

4. A laminated multi-electrode battery cell as claimed in claim 1, characterized in that: There are (2n+4) positive electrode sheets and (2n+5) negative electrode sheets; wherein n is an integer not less than 1; the height of the (2n-1)th negative electrode tab and the height of the (2n)th positive electrode tab are respectively the sum of the width of the tab pre-weld weld mark and the distance from the bottom of the weld mark to the top of the tab side of the battery cell.

5. A laminated multi-electrode battery cell as claimed in claim 4, characterized in that: According to the stacking direction, with the (2n-1)th negative electrode tab as the center, the heights of the negative electrode tabs on both sides of the center are symmetrically arranged.

6. A laminated multi-electrode battery cell as claimed in claim 4, characterized in that: According to the stacking direction, with the (2n)th positive electrode tab as the center, the heights of the positive electrode tabs on both sides of the center are symmetrically arranged.

7. A laminated multi-electrode battery cell as claimed in claim 1, characterized in that: The positive electrode tab and the negative electrode tab both have a trapezoidal structure.

8. A laminated multi-electrode battery cell as claimed in claim 1, characterized in that: The number of the separator layers is twice the number of the negative electrode sheets.

9. A lithium battery, characterized in that: A laminated multi-pole battery cell comprising any one of claims 1 to 8.

10. A vehicle, characterized in that: A lithium battery as claimed in claim 9 is used.

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