Multi-tab winding type laminated battery cell structure

Abstract

The utility model belongs to the technical field of electrochemical energy storage, and discloses a multi-tab winding type laminated cell structure, which is formed by winding a positive pole piece, a negative pole piece and a diaphragm, the positive pole piece and the negative pole piece are respectively provided with 2n tabs, and n is the number of turns of cell winding; two tabs exist when the positive pole piece and the negative pole piece are wound by one circle, and the two tabs of each circle of the positive pole piece and the negative pole piece are symmetrically distributed on the two sides of the roll core; all tabs after the positive pole piece is wound are arranged side by side to form a positive pole tab of the battery cell; and after the negative pole piece is wound, all tabs of the negative pole piece are arranged side by side to form a negative pole tab of the battery cell. According to the utility model, high-efficiency production can be realized in a winding manner, the battery has low battery core internal resistance comparable to that of a laminated battery, meanwhile, the dislocation of the tabs is relatively small, and the weight and the cost of the battery are reduced; therefore, the rate capability of the battery is improved, and meanwhile, the production efficiency and the yield are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of electrochemical energy storage, and specifically relates to a battery core structure of a lithium ion battery. Background Art

[0002] As a new energy electrochemical energy storage device, lithium-ion batteries currently have two main production methods for battery cells: winding and stacking. Compared with the winding method, stacked batteries have multiple layers of pole pieces and each layer of pole pieces leads to a pole ear, and then the single pole ears are connected to each other by welding. This connection method is equivalent to connecting all the pole pieces in parallel, thereby reducing the internal resistance of the battery. However, the complex production method of stacked batteries leads to low production efficiency and poor consistency. Usually, a wound battery has only one pole ear for two layers of pole pieces wound in one circle, so the electron transmission path is longer for the pole piece, which results in a large internal resistance of the battery, poor rate, and increased temperature. However, the winding mechanism of the wound battery has a faster winding speed and high production efficiency. Utility Model Content

[0003] The utility model focuses on solving the technical problems of large internal resistance of wound cells and low production efficiency of stacked cells, and provides a multi-electrode wound stacked cell structure. By optimizing the wound cell structure, it has the advantages of both the production efficiency of wound cells and the small internal resistance of stacked cells, and is suitable for the industrial application of lithium-ion batteries.

[0004] In order to achieve the above-mentioned purpose of the invention, the utility model is implemented through the following technical solutions:

[0005] The utility model provides a multi-electrode winding laminated battery core structure, which is wound by a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet and the negative electrode sheet are both provided with 2n electrode sheets, and n is the number of turns of the battery core; each time the positive electrode sheet and the negative electrode sheet are wound, there are two electrode sheets, and the two electrode sheets of each turn in the positive electrode sheet are symmetrically distributed on both sides of the winding core, and the two electrode sheets of each turn in the negative electrode sheet are symmetrically distributed on both sides of the winding core;

[0006] After the positive electrode sheet is wound, all the tabs thereof are arranged side by side to form the positive electrode tab of the battery cell; after the negative electrode sheet is wound, all the tabs thereof are arranged side by side to form the negative electrode tab of the battery cell; and there is a distance between the positive electrode tab and the negative electrode tab on the winding core.

[0007] Furthermore, for the positive electrode sheet and the negative electrode sheet, the innermost tab of the battery cell manufactured by winding is the first tab, and the distances between adjacent tabs are L1 to L2n respectively; wherein L1, L3, L5 ... L(2n-1) are odd-numbered tab distances, and L2, L4, L6, ... L2n are even-numbered tab distances; by designing different ΔLa and ΔLb, all the tabs of the positive electrode sheet are located at the same position of the battery cell body, and all the tabs of the negative electrode sheet are located at another same position of the battery cell body; wherein ΔLa is the increment of the odd-numbered tab distances, and ΔLb is the increment of the even-numbered tab distances.

[0008] Furthermore, ΔLa=m*ΔC, 5%≤m≤95%; ΔLa+ΔLb=ΔC; ΔC is the circumference increment of the outer pole piece relative to the inner pole piece in two adjacent turns caused by the increase in the number of winding turns of the battery cell.

[0009] Furthermore, n≥2, 10mm≤L1~Ln≤500mm.

[0010] Furthermore, in two adjacent circles of positive electrode sheets, the width of the outer circle of the pole lug is smaller than the width of the inner circle of the pole lug, and in two adjacent circles of negative electrode sheets, the width of the outer circle of the pole lug is smaller than the width of the inner circle of the pole lug.

[0011] Furthermore, for the positive electrode sheet and the negative electrode sheet, the difference in width between the outer ring and the inner ring of the ear is Δt, Δt = (T 外 -T 内 ) / n; where T 外 is the width of the outermost lug, T 内 is the width of the innermost lug, and n is the number of turns of the battery cell.

[0012] The beneficial effects of the utility model are:

[0013] Compared with the prior art, the utility model can achieve high-efficiency production through winding, and has a low cell internal resistance comparable to that of a laminated battery, while also ensuring that the tab misalignment is small, reducing battery weight and cost; thus, the battery rate performance is improved, while the production efficiency and yield are improved.

[0014] Firstly, a multi-ear symmetrical design is adopted to ensure that there are two ears for each circle of positive electrode sheets and negative electrode sheets, that is, there is one ear for each layer of electrode sheets. The parallel connection of multiple layers of electrode sheets reduces the internal resistance of the battery and improves the rate performance of the battery. In addition, due to the increase in the number of ears, the cumulative tolerance of the ear position continues to increase with the increase in the number of winding layers, and the ears are more likely to be misaligned. Therefore, the utility model also adopts a size gradient method for the ear processing. The size of the outer ring ear is smaller than the width of the inner ring ear to ensure the alignment of the ears, thereby reducing the ear misalignment caused by the tolerance accumulation.

[0015] It can be seen that the utility model not only solves the disadvantage of large internal resistance of wound battery cells, but also solves the disadvantage of low production efficiency of stacked battery cells, and is suitable for industrial application of lithium-ion batteries; finally, the direct welding technology of the ear and the cover plate is adopted to eliminate the use of the connecting plate, reduce the weight of the battery, reduce the cost, and at the same time reduce the internal resistance of the battery welding point, thereby achieving the purpose of reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The expanded diagram of the pole piece used in traditional winding; where: 1-1 is the pole piece; 1-2 is the pole ear; L1, L2, L3 are the distances between the pole ears;

[0017] Figure 2 The figure above is an unfolded view of the pole piece used in the multi-pole winding laminated cell structure, and its pole pieces have the same size; among them: 2-1 is the pole piece; 2-2 is the pole piece; Figure 2 The figure below is an unfolded diagram of the pole piece used in the multi-pole winding laminated battery cell, and the width of the pole piece changes gradually; among them: 2-3 is the pole piece, 2-4 is the pole piece; L1~Ln is the distance between the pole pieces;

[0018] Figure 3 The front view and top view of the multi-electrode winding laminated battery cell structure of the utility model; wherein: 3-1 is the battery cell body; 3-2 is the positive electrode ear; 3-3 is the negative electrode ear;

[0019] Figure 4 The front view and top view of the traditional wound battery cell structure; wherein: 4-1 is the battery cell body; 4-2 is the positive electrode ear; 4-3 is the negative electrode ear;

[0020] Figure 5 This is a schematic diagram of a battery structure in which a multi-electrode winding laminated battery structure of the utility model is prepared using pole pieces with equal-sized poles; wherein: 5-1 is the battery body; 5-2 is the positive pole ear; 5-3 is the negative pole ear;

[0021] Figure 6 This is a schematic diagram of a battery cell structure in which a multi-electrode winding laminated battery cell structure of the utility model is prepared using a pole piece with a gradually varying pole ear; wherein: 6-1 is the battery cell body; 6-2 is the positive pole ear; and 6-3 is the negative pole ear. DETAILED DESCRIPTION

[0022] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods. In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution of the embodiments of the utility model will be clearly and completely described below in conjunction with the example diagrams of the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the described embodiments of the utility model, all other embodiments obtained by those skilled in the art belong to the protection scope of the utility model.

[0023] The utility model provides a multi-electrode winding laminated battery cell structure, which is wound by a positive electrode sheet, a negative electrode sheet and a diaphragm. The positive electrode sheet and the negative electrode sheet are both provided with 2n electrode ears, where n is the number of turns of the battery cell, that is, there are two electrode ears for each turn of the positive electrode sheet and the negative electrode sheet. For the positive electrode sheet, the two electrode ears of each turn are symmetrically distributed on both sides of the winding core; for the negative electrode sheet, the two electrode ears of each turn are symmetrically distributed on both sides of the winding core. After the positive electrode sheet is wound, all its electrode ears are basically aligned, forming the positive electrode ear of the battery cell side by side. After the negative electrode sheet is wound, all its electrode ears are basically aligned, forming the negative electrode ear of the battery cell side by side. The positive electrode ear and the negative electrode ear of the battery cell have a spacing on the winding core.

[0024] The innermost tab of the battery cell produced when the pole piece is wound is the first tab, and the first tab is closest to the cutting position of the pole piece. In this way, the distances between adjacent tabs are L1 to L2n, where L1, L3, L5...L(2n-1) are odd-numbered tab distances, and L2, L4, L6,...L2n are even-numbered tab distances. By designing different odd-numbered tab distance increments ΔLa and even-numbered tab distance increments ΔLb, all tabs of the positive pole piece are located at the same position of the battery cell body, and all tabs of the negative pole piece are located at another same position of the battery cell body.

[0025] As a preferred solution, n≥2, 10mm≤L1~Ln≤500mm; the distances between two adjacent odd-numbered pole tabs L(2m-1) and L(2m+1) increase by ΔLa, and the distances between two adjacent even-numbered pole tabs L2m and L(2m+2) increase by ΔLb; wherein m is 1…n-1.

[0026] Among them, ΔLa+ΔLb=ΔC, ΔC is the circumference increment of the outer pole piece relative to the inner pole piece in two adjacent turns caused by the increase in the number of turns of the battery cell, ΔC=2π(r 外 -r 内 ), r 外 is the radius length of the outer pole piece in two adjacent turns when winding, r 内 is the radius length of the inner pole piece in two adjacent turns when winding. Preferably, ΔLa=m*ΔC (5%≤m≤95%).

[0027] In addition, as n increases, the size of the tabs in each circle of the positive and negative pole sheets is the same, and the width of the tabs in two adjacent circles decreases by the difference of Δt. In other words, the width of the outer tab in two adjacent circles of the positive and negative pole sheets is smaller than the width of the inner tab, and the width difference is Δt. Δt=(T 外 -T 内 ) / n,T 外 is the width of the outermost lug, T 内 is the width of the innermost lug, and n is the number of turns of the battery cell.

[0028] The method for manufacturing the multi-electrode wound laminated battery core structure comprises the following steps:

[0029] The positive and negative pole pieces are die-cut to designed sizes by laser or hardware knife, and the positive and negative pole pieces and the separator are wound on a winding machine to obtain the multi-electrode winding stacked battery cell as described above.

[0030] As a preferred embodiment, the die-cutting method comprises the following steps:

[0031] S1, a complete pole piece required for cell winding as the total pole piece length C;

[0032] S2. Mark holes are cut out of the pole pieces in the die-cutting machine to distinguish the head and tail of different pole pieces;

[0033] S3, set the length of the electrode inserted into the battery cell as length S1, which is the distance from the MArk hole to the first pole ear of the electrode;

[0034] S4, setting the initial lengths of L1 and L2 according to the insertion length of the electrode sheet winding inside the battery cell and the center distance of the electrode lugs, and designing the position of each electrode lug according to the increments ΔLa and ΔLb of the odd-numbered electrode lug spacing and the even-numbered electrode lug spacing;

[0035] S5. Set the pole piece tail length Sn according to the total pole piece length C: Sn = CS-(L1+L2+...Ln)

[0036] S6, repeat S1 to S5 until all the pole pieces are die-cut.

[0037] The multi-tab wound laminated battery cell and the cover plate are directly connected by laser welding to form a finished battery product.

[0038] Comparative Example 1

[0039] Figure 1 The figure shows the pole piece used in the traditional winding method of preparing the battery cell; Figure 4 Shown is a battery cell prepared by conventional winding method.

[0040] The total length of the positive electrode sheet 1-1 is 13125 mm, and the total length of the negative electrode sheet 1-1 is 13425 mm.

[0041] When the positive electrode is die-cut, the insertion length S1 of the positive electrode sheet 1-1 inside the battery cell is 190mm, the distance L1 between the first pole ear 1-2 and the second pole ear 1-2 is 293.3mm, the distances between the pole ears 1-2 from L1 to Ln are close, and are in equal increments of 1.91mm, the number n of the pole ears 1-2 is 38, the positive electrode tail length Sn is 380mm, and the pole sheet thickness is 133μm.

[0042] When the negative electrode is die-cut, the insertion length S1 of the negative electrode sheet 1-1 inside the battery cell is 220mm, ensuring that the negative electrode insertion length covers the positive electrode insertion length. The distance L1 between the first pole ear 1-2 and the second pole ear 1-2 is 292.4mm. The distances between the pole ears L1~Ln 1-2 are close and have equal increments of 1.91mm. The number n of the pole ears 1-2 is 39. The negative electrode tail length is 20mm, ensuring that the negative electrode tail covers the positive electrode tail. The pole sheet thickness is 95μm.

[0043] The die-cut positive electrode sheet 1-1, negative electrode sheet 1-1 and 12 μm thick separator are wound on a winding machine to obtain Figure 4 In the conventional winding battery cell shown, each time the positive electrode sheet 1-1 and the negative electrode sheet 1-1 are wound one circle, there is one electrode tab, so that the positive electrode tab 4-2 and the negative electrode tab 4-3 are distributed on a single side of the battery cell body 4-1.

[0044] Embodiment 1

[0045] Figure 2 The figure above shows the pole piece of a wound laminated multi-pole battery cell; Figure 3 The figure shows a wound laminated multi-pole battery cell; the spacing between two adjacent odd-numbered poles L(2m-1) and L(2m+1) increases by ΔLa, and the spacing between two adjacent even-numbered poles L2m and L(2m+2) increases by ΔLb.

[0046] The total length of the positive electrode sheet 2-1 is 15413 mm, and the total length of the negative electrode sheet 2-1 is 15759 mm. The tabs 2-2 of the positive electrode sheet 2-1 and the negative electrode sheet 2-1 are of the same size.

[0047] When the positive electrode is die-cut, the insertion length S1 of the positive electrode sheet 2-1 inside the battery cell is 126.98 mm, the spacing L1 between the first pole ear 2-2 and the second pole ear 2-2 is the first spacing between the odd-numbered pole ears 2-2, which is 63 mm, and the increment ΔLa of the spacings L(2m-1) and L(2m+1) between two adjacent odd-numbered pole ears 2-2 is 0.83; the spacing L2 between the second pole ear 2-2 and the third pole ear 2-2 is the first spacing between the even-numbered pole ears, which is 227.43 mm, and the increment ΔLb of the spacings L2m and L(2m+2) between two adjacent even-numbered pole ears 2-2 is 0.73, the number 2n of the pole ears 2-2 is 76, the tail length Sn of the positive electrode sheet 2-1 is 260 mm, and the thickness of the positive electrode sheet 2-1 is 133 μm.

[0048] When the negative electrode is die-cut, the insertion length S1 of the negative electrode sheet 2-1 inside the battery cell is 232 mm, the spacing L1 between the first pole ear 2-2 and the second pole ear 2-2 is the first spacing between the odd-numbered pole ears 2-2, which is 63.54 mm, and the increment ΔLa of the spacing L(2m-1) and L(2m+1) of the two odd-numbered pole ears 2-2 is 0.86; the spacing L2 between the second pole ear 2-2 and the third pole ear 2-2 is the first spacing between the even-numbered pole ears, which is 227.54 mm, and the increment ΔLb of the spacing L2n and L2n+2 of the two even-numbered pole ears 2-2 is 0.78, the number 2n of the pole ears 2-2 is 78, the tail length Sn of the negative electrode sheet 2-1 is 103 mm, and the thickness of the negative electrode sheet 2-1 is 95 μm.

[0049] The die-cut positive electrode sheet 2-1, negative electrode sheet 2-1 and 12 μm thick separator are wound on a winding machine to obtain Figure 3 In the wound laminated multi-electrode battery cell shown, the positive electrode tab 3-2 and the negative electrode tab 3-3 are distributed on both sides of the battery cell body 3-1, and there are two tabs in each circle of the positive electrode sheet 2-1 and the negative electrode sheet 2-1.

[0050] Figure 5 The cell is made of pole pieces with equal-sized pole tabs used in wound laminated multi-pole tab cells. The positive pole tab 5-2 and the negative pole tab 5-3 on the cell body 5-1 are outwardly misaligned due to tolerance; the cell is directly connected to the cover plate by laser welding to form a finished battery. Compared with comparative example 1, the internal resistance of this embodiment is significantly reduced.

[0051] Embodiment 2

[0052] Figure 2 The figure below shows the pole piece of a wound laminated multi-pole battery cell; Figure 6 It is a wound laminated multi-pole battery cell; the spacing between two adjacent odd-numbered poles L(2m-1) and L(2m+1) increases by ΔLa, and the spacing between two adjacent even-numbered poles L2m and L(2m+2) increases by ΔLb.

[0053] The total length of the positive electrode sheet 2-3 is 15413 mm, and the total length of the negative electrode sheet 2-3 is 15759 mm.

[0054] When the positive electrode is die-cut, the insertion length S1 of the positive electrode sheet 2-3 inside the battery cell is 126.98mm, the spacing L1 between the first pole ear 2-4 and the second pole ear 2-4 is the first spacing of the odd-numbered pole ears 2-4, which is 63mm, and the increment ΔLa of the spacing L(2m-1) and L(2m+1) of the two odd-numbered pole ears 2-4 is 0.83; the spacing L2 between the second pole ear 2-4 and the third pole ear 2-4 is the first spacing of the even-numbered pole ears 2-4, which is 227.43mm, and the increment ΔLb of the spacing L2m and L(2m+2) of the two even-numbered pole ears 2-4 is 0.73; the width direction dimension of the pole ear 2-4 decreases by 0.1mm from L1 to Ln, the number 2n of the pole ears 2-2 is 76, the tail length Sn of the positive pole sheet 2-3 is 260mm, and the thickness of the positive pole sheet 2-3 is 133μm.

[0055] When the negative electrode is die-cut, the insertion length S1 of the negative electrode sheet 2-3 inside the battery cell is 232mm, the spacing L1 between the first pole ear 2-4 and the second pole ear 2-4 is the first spacing of the odd-numbered pole ears 2-4, which is 63.54mm, and the increment ΔLa of the spacing L(2m-1) and L(2m+1) of the two odd-numbered pole ears 2-4 is 0.86; the spacing L2 between the second pole ear 2-4 and the third pole ear 2-4 is the first spacing of the even-numbered pole ears, which is 227.54mm, and the increment ΔLb of the spacing L2m and L(2m+2) of the two even-numbered pole ears 2-4 is 0.78; the width direction dimension of the pole ear 2-4 decreases by 0.1mm from L1 to Ln, the number 2n of the pole ears 2-2 is 78, the tail length Sn of the positive pole sheet 2-3 is 103mm, and the thickness of the positive pole sheet 2-3 is 95μm.

[0056] The die-cut positive electrode sheet 2-3, negative electrode sheet 2-3 and 12 μm thick separator are wound on a winding machine to obtain Figure 3 In the wound laminated multi-electrode tab battery cell shown, the positive electrode tab 3-2 and the negative electrode tab 3-3 are distributed on both sides of the battery cell body 3-1, and there are two tabs in each circle of the positive electrode sheet 2-3 and the negative electrode sheet 2-3.

[0057] Figure 6 The battery cell is made of a pole sheet with a gradually changing pole size used in a wound laminated multi-pole-ear battery cell, and the positive pole ear 6-2 and the negative pole ear 6-3 have a reduced dislocation of the gathered position on the battery cell body 6-1; the battery cell is directly connected to the cover plate by laser welding to form a finished battery. Compared with the comparative example 1, the internal resistance of this embodiment is significantly reduced; compared with the example 1, the dislocation of the gathered position of the positive pole ear 6-2 and the negative pole ear 6-3 to both sides is significantly reduced.

[0058] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A multi-electrode winding laminated battery cell structure, which is wound by a positive electrode sheet, a negative electrode sheet and a separator, characterized in that: The positive electrode sheet and the negative electrode sheet are both provided with 2n pole tabs, where n is the number of turns of the battery cell; each time the positive electrode sheet and the negative electrode sheet are wound one turn, there are two pole tabs, and the two pole tabs of each turn of the positive electrode sheet are symmetrically distributed on both sides of the winding core, and the two pole tabs of each turn of the negative electrode sheet are symmetrically distributed on both sides of the winding core; After the positive electrode sheet is wound, all the tabs thereof are arranged side by side to form the positive electrode tab of the battery cell; after the negative electrode sheet is wound, all the tabs thereof are arranged side by side to form the negative electrode tab of the battery cell; and there is a distance between the positive electrode tab and the negative electrode tab on the winding core.

2. The multi-electrode wound laminated battery structure according to claim 1, characterized in that: For the positive electrode sheet and the negative electrode sheet, the innermost tab of the battery cell manufactured by winding is the first tab, and the distances between adjacent tabs are L1 to L2n respectively; wherein L1, L3, L5 ... L(2n-1) are odd-numbered tab distances, and L2, L4, L6, ... L2n are even-numbered tab distances; by designing different ΔLa and ΔLb, all the tabs of the positive electrode sheet are located at the same position of the battery cell body, and all the tabs of the negative electrode sheet are located at another same position of the battery cell body; wherein ΔLa is the increment of the odd-numbered tab distances, and ΔLb is the increment of the even-numbered tab distances.

3. The multi-electrode wound laminated battery cell structure according to claim 2, characterized in that: ΔLa=m*ΔC, 5%≤m≤95%; ΔLa+ΔLb=ΔC; ΔC is the circumference increment of the outer pole piece relative to the inner pole piece in two adjacent turns caused by the increase in the number of winding turns of the battery cell.

4. The multi-electrode wound laminated battery structure according to claim 1, characterized in that: Said n≥2, 10mm≤L1~Ln≤500mm.

5. The multi-electrode wound laminated battery structure according to claim 1, characterized in that: The width of the outer ear of two adjacent circles of positive electrode sheets is smaller than the width of the inner ear, and the width of the outer ear of two adjacent circles of negative electrode sheets is smaller than the width of the inner ear.

6. The multi-electrode wound laminated battery structure according to claim 5, characterized in that: For the positive electrode and the negative electrode, the difference between the outer and inner ear widths is Δt, Δt = (T 外 -T 内 ) / n; where T 外 is the width of the outermost lug, T 内 is the width of the innermost lug, and n is the number of turns of the battery cell.

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