Multi-tab winding battery cell and preparation method thereof

Abstract

The invention discloses a multi-tab winding battery cell which comprises a winding core formed by sequentially stacking and winding a first pole piece, a diaphragm and a second pole piece, the first pole piece is provided with a plurality of first tabs along the length direction of the pole piece, and the second pole piece is provided with a plurality of second tabs along the length direction of the pole piece; the plurality of second tabs are sequentially stacked to form a U-shaped second tab group, and the first tab group and the second tab group are respectively positioned at corners on two sides of the roll core; the distance between the forward projection of the first tab group and the forward projection of the second tab group in the thickness direction of the battery cell is a, and a is greater than 0 mm. Compared with the prior art, the multi-tab winding battery cell provided by the invention has the advantages that the design of the wide tabs provides a wider external tab welding base station for the battery cell, and meanwhile, the battery can keep higher efficiency in the charging and discharging processes; and the distribution of the current on the pole piece is more uniform, and the problems of local overheating and performance reduction are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a multi-electrode winding battery core and a preparation method thereof. Background Art

[0002] Lithium-ion batteries, with their many advantages such as excellent high energy density, high safety, environmental protection and design flexibility, have shown broad application prospects in many fields such as digital products and information communications.

[0003] Multi-electrode winding batteries, with their unique multi-electrode structure, have achieved low internal resistance, low temperature rise, and high-rate charge and discharge capabilities, and have been widely used in various digital products. In its related technologies, it is usually necessary to determine the length and width of the positive and negative pole pieces and the spacing between the pole pieces according to the specific model through precise theoretical calculations, and then use the winding process to make the final battery cell. However, in the actual production process, due to the precision limitations of the production equipment and fluctuations in the production process, the consistency of the pole pieces is poor, which makes it difficult to align the pole pieces of the multi-electrode winding battery cell, which not only affects the welding quality of the battery cell, but also leads to problems such as uneven center size of the pole pieces, which ultimately seriously affects the yield rate and production efficiency.

[0004] In addition, digital battery products come in various forms, most of which are customized in size. For each product form, the pole piece size and pole ear position need to be precisely designed and die-cut. This process is complex and has low universality.

[0005] In view of the above problems still existing in the tabs of the current multi-tab wound battery cells, it is indeed necessary to provide a technical solution to the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-tab wound battery cell, further adjust the width and position of the tabs, provide a wider external tab welding base, reduce the die-cutting accuracy requirements, and improve the product yield.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A multi-electrode winding battery core, comprising a winding core formed by stacking and winding a first pole piece, a diaphragm and a second pole piece in sequence;

[0009] The first pole piece is provided with a plurality of first pole lugs along the length direction of the pole piece, and the second pole piece is provided with a plurality of second pole lugs along the length direction of the pole piece; the polarities of the first pole piece and the second pole piece are opposite;

[0010] A plurality of the first pole lugs are stacked in sequence to form a first pole lug group, and a plurality of the second pole lugs are stacked in sequence to form a second pole lug group. The first pole lug group and the second pole lug group are respectively located at the corners on both sides of the winding core, so that the first pole lug group and the second pole lug group both form U-shaped pole lug groups; there is a spacing a between the forward projections of the first pole lug group and the second pole lug group along the thickness direction of the battery cell, and a>0mm.

[0011] Preferably, the widths of the first to nth first pole ears of the first pole piece are A1, A2, ....An respectively, the thickness of the first pole piece is T1; the thickness of the second pole piece is T2; wherein A1 and An satisfy the relationship: An=A1+(n-1)×π×(T1+T2+2×T3), n≥1.

[0012] Preferably, the widths of the first to the nth second pole ears of the second pole piece are C1, C2, ..., Cn respectively; C1 and A1 satisfy the relationship: C1=A1.

[0013] Preferably, the C1 and the Cn-1 satisfy the relationship: C1 and Cn-1 satisfy the relationship: Cn-1=C1+(n-2)×π×(T1+T2+2×T3);

[0014] When n is an odd number, the width Cn of the nth second pole ear satisfies the relationship: Cn=C1+(n-1)×π×(T1+T2+2×T3);

[0015] When n is an even number, the width Cn of the nth second pole tab satisfies the relationship: 2Cn=C1+(n-1)×π×(T1+T2+2×T3).

[0016] Preferably, the distance between the n+1th pole lug and the nth pole lug of the first pole piece is En, and En satisfies the relationship: En>An.

[0017] Preferably, the distance between the n+1th pole lug and the nth pole lug of the second pole piece is Fn, and Fn satisfies the relationship: Fn>Cn.

[0018] Preferably, A1 is 5-300 mm.

[0019] Preferably, C1 is 5-300 mm.

[0020] Preferably, the coating width of the first pole piece is B, the coating width of the second pole piece is D, and B and D satisfy the relationship: D>B.

[0021] The present invention also provides a method for preparing a multi-electrode wound battery cell, comprising the following steps:

[0022] Step 1: Set the values ​​of A1, C1, E1 and F1, measure the thickness T1 of the diaphragm, the thickness T2 of the first pole piece, the thickness T3 of the second pole piece, calculate the spacing and width of the multi-electrode tabs, and die-cut according to the set data;

[0023] Step 2: Wind the first pole piece, the separator and the second pole piece in sequence to obtain a multi-electrode wound battery cell.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a multi-tab wound battery cell. When the battery cell is rolled up, only the spacing of the forward projections of the first tab group and the second tab group along the thickness direction of the battery cell is limited to be greater than 0 mm, and a relatively large tab width can be adopted. On the one hand, the design of the wide tab provides the battery cell with a wider external tab welding base, reduces the die-cutting accuracy requirements, and improves the product yield; at the same time, it helps the battery to maintain a higher efficiency during the charging and discharging process; it can also make the current distribution on the pole piece more uniform, avoiding the problems of local overheating and performance degradation; further, the wider tab can also provide a larger contact area and stronger structural support, thereby improving the mechanical strength and durability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a forward projection in the thickness direction of a wound battery cell according to an embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a first pole piece according to an embodiment of the present invention;

[0027] Figure 3 Schematic diagram of the structure of the second pole piece according to an embodiment of the present invention.

[0028] Among them, 1, first pole piece; 11, first pole lug group; 111, first pole lug; 2, second pole piece; 21, second pole lug group; 211, second pole lug; 3, winding core. DETAILED DESCRIPTION

[0029] In order to make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] According to a first aspect of the present invention, the present invention provides a multi-electrode wound battery cell, comprising a winding core 3 formed by stacking and winding a first pole piece 1, a separator, and a second pole piece 2 in sequence;

[0031] The first pole piece 1 is provided with a plurality of first pole ears 111 along the length direction of the pole piece, and the second pole piece 2 is provided with a plurality of second pole ears along the length direction of the pole piece; the polarities of the first pole piece and the second pole piece are opposite;

[0032] A plurality of first pole tabs are stacked in sequence to form a first pole tab group, and a plurality of second pole tabs are stacked in sequence to form a second pole tab group. The first pole tab group and the second pole tab group are respectively located at the corners on both sides of the winding core, so that the first pole tab group and the second pole tab group both form U-shaped pole tab groups; there is a spacing a between the forward projections of the first pole tab group and the second pole tab group along the thickness direction of the battery cell, and a>0mm.

[0033] The multi-tab wound battery cell of the present invention adjusts the forward projection spacing between the first tab group 11 and the second tab group 21 in the thickness direction of the battery cell to ensure that the spacing is greater than 0 mm, thereby allowing a relatively wide tab design. This innovative design brings multiple advantages: first, the wide tab provides a wider external tab welding platform for the battery cell, effectively reducing the requirements for die-cutting accuracy and significantly improving the product qualification rate; second, the wide tab design helps the battery maintain higher efficiency during the charging and discharging process, ensuring smooth and efficient energy conversion; third, it can also promote the uniform distribution of current on the pole piece, effectively prevent local overheating, avoid performance degradation, and ensure the stable operation of the battery; further, the wide tab not only increases the contact area, but also enhances the support of the structure, thereby significantly improving the mechanical strength and durability of the battery, providing a solid guarantee for the long-term use of the battery.

[0034] In one embodiment of the present invention, the widths of the first to nth first pole tabs 111 of the first pole sheet 1 are A1, A2, .... An, respectively, and the thickness of the first pole sheet 1 is T1; the thickness of the second pole sheet 2 is T2; wherein A1 and An satisfy the relationship: An = A1 + (n-1) × π × (T1 + T2 + 2 × T3), n ≥ 1. The width of An is calculated by this formula, and finally a multi-pole tab with gradually widening from A1 to An can be obtained, and finally the pole tab is bent toward the bending direction of the battery cell, and stacked to form a U-shaped first pole tab group 11.

[0035] In one embodiment of the present invention, the widths of the first to the nth second pole tabs of the second pole piece 2 are C1, C2, ..., Cn respectively; wherein C1 and A1 satisfy the relationship: C1=A1.

[0036] In one embodiment of the present invention, C1 and Cn-1 satisfy the relationship: Cn-1=C1+(n-2)×π×(T1+T2+2×T3); the width of Cn is calculated by this formula, and finally a multi-pole ear with gradually widening from C1 to Cn-1 can be obtained, and finally the pole ear is bent toward the bending direction of the battery cell and stacked to form a U-shaped second pole ear group 21.

[0037] When n is an odd number, the width Cn of the nth second pole ear satisfies the relationship: Cn=C1+(n-1)×π×(T1+T2+2×T3);

[0038] When n is an even number, the width Cn of the nth second pole tab satisfies the relationship: 2Cn=C1+(n-1)×π×(T1+T2+2×T3).

[0039] The width of Cn is calculated by the formula, and finally the second pole lug group 21 bent toward the bending direction of the battery cell and stacked to form a U-shape can be obtained. It should be noted that for the nth second pole lug, when n is an odd number, the width Cn of the nth second pole lug satisfies the relationship: Cn=C1+(n-1)×π×(T1+T2+2×T3); when n is an even number, the width Cn of the nth second pole lug satisfies the relationship: 2Cn=C1+(n-1)×π×(T1+T2+2×T3).

[0040] The multi-ear tab design of the battery cell of the present invention shows a trend of gradually widening from the first ear to the last ear; the design of increasing width enables relatively wide ears to carry the flow of large currents, thereby effectively promoting efficiency improvement during the charging and discharging cycle of the battery. In addition, it can also promote a more balanced distribution of current on the electrode, effectively avoiding the hidden dangers of local overheating and performance degradation. Furthermore, the widened ears not only provide a wider contact surface, but also significantly enhance the support force of the structure, thereby fundamentally improving the mechanical stability and durability of the battery.

[0041] In one embodiment of the present invention, the distance between the n+1th pole lug and the nth pole lug of the first pole piece 1 is En, and En satisfies the relationship: En>An.

[0042] In one embodiment of the present invention, the distance between the n+1th pole lug and the nth pole lug of the second pole piece 2 is Fn, and Fn satisfies the relationship: Fn>Cn.

[0043] In one embodiment according to the present invention, A1 is 5-300 mm.

[0044] In one embodiment of the present invention, C1 is 5-300 mm.

[0045] In one embodiment of the present invention, the coating width of the first pole piece 1 is B, the coating width of the second pole piece 2 is D, and B and D satisfy the relationship: D> B. Generally speaking, the second pole piece 2 is a negative electrode, and the first pole piece 1 is a positive electrode, and the coating width of the active material of the negative electrode is greater than the coating width of the active material of the positive electrode.

[0046] According to a second aspect of the present invention, the present invention also provides a method for preparing a multi-electrode wound battery cell, comprising the following steps:

[0047] Step 1: Set the values ​​of A1, C1, E1 and F1, measure the thickness T1 of the diaphragm, the thickness T2 of the first pole piece 1, the thickness T3 of the second pole piece 2, and calculate the spacing and width of the multi-pole ears, and die-cut according to the set data; wherein, C1=A1; A1 and An satisfy the relationship: An=A1+(n-1)×π×(T1+T2+2×T3); C1 and Cn satisfy the relationship: Cn=C1+(n-1)×π(T1+T2+2×T3), when n is an even number, the width Cn of the nth second pole ear satisfies the relationship: 2Cn=C1+(n-1)×π×(T1+T2+2×T3); and E(n-1)>A(n-1), F(n-1)>C(n-1), calculate the spacing and width of the multi-pole ears according to these data formulas, and die-cut according to the set data.

[0048] Step 2: Wind the first pole piece 1, the separator and the second pole piece 2 in sequence to obtain a multi-electrode wound battery cell.

[0049] The die-cutting precision requirement of this battery cell is low, which can avoid the problems of misalignment of the tabs, inconsistent welding area and unstable center distance caused by the fluctuation of the thickness of the positive and negative pole pieces and the diaphragm and the fluctuation of the entry position. At the same time, it can reduce the die-cutting precision of the pole pieces and improve the production yield. Compared with other complex manufacturing processes, this design can simplify the production process and reduce manufacturing costs.

[0050] In one embodiment of the present invention, the multi-tab wound battery cell in step 2 can be subjected to secondary die-cutting of the first tab group 11 and the second tab group 21 as required.

[0051] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A multi-electrode wound battery cell, characterized in that: It includes a winding core formed by stacking and winding a first pole piece, a diaphragm, and a second pole piece in sequence; The first pole piece is provided with a plurality of first pole ears along the length direction of the pole piece, and the second pole piece is provided with a plurality of second pole ears along the length direction of the pole piece; the polarities of the first pole piece and the second pole piece are opposite; A plurality of the first pole lugs are stacked in sequence to form a first pole lug group, and a plurality of the second pole lugs are stacked in sequence to form a second pole lug group. The first pole lug group and the second pole lug group are respectively located at the corners on both sides of the winding core, so that the first pole lug group and the second pole lug group both form U-shaped pole lug groups; there is a spacing a between the forward projections of the first pole lug group and the second pole lug group along the thickness direction of the battery cell, and a>0mm.

2. The multi-electrode wound battery cell according to claim 1, characterized in that: The widths of the first to nth first pole ears of the first pole piece are A1, A2, ....An respectively, the thickness of the first pole piece is T1; the thickness of the second pole piece is T2; wherein A1 and An satisfy the relationship: An=A1+(n-1)×π×(T1+T2+2×T3), n≥1.

3. The multi-electrode wound battery cell according to claim 2, characterized in that: The widths of the first to the nth second pole ears of the second pole piece are C1, C2, ....Cn respectively; C1 and A1 satisfy the relationship: C1=A1.

4. The multi-electrode wound battery cell according to claim 3, characterized in that: The C1 and the Cn-1 satisfy the relationship: Cn-1=C1+(n-2)×π×(T1+T2+2×T3); When n is an odd number, the width Cn of the nth second pole ear satisfies the relationship: Cn=C1+(n-1)×π×(T1+T2+2×T3); When n is an even number, the width Cn of the nth second pole tab satisfies the relationship: 2Cn=C1+(n-1)×π×(T1+T2+2×T3).

5. The multi-electrode wound battery cell according to claim 2, characterized in that: The distance between the n+1th pole lug and the nth pole lug of the first pole piece is En, and En satisfies the relationship: En>An.

6. The multi-electrode wound battery cell according to claim 2, characterized in that: The distance between the n+1th pole lug and the nth pole lug of the second pole piece is Fn, and Fn satisfies the relationship: Fn>Cn.

7. The multi-electrode wound battery cell according to claim 2, characterized in that: The A1 is 5-300 mm.

8. The multi-electrode wound battery cell according to claim 3, characterized in that: The C1 is 5-300 mm.

9. The multi-electrode wound battery cell according to claim 1, characterized in that: The coating width of the first pole piece is B, the coating width of the second pole piece is D, and B and D satisfy the relationship: D>B.

10. A method for preparing a multi-electrode wound battery cell according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Set the values ​​of A1, C1, E1 and F1, measure the thickness T3 of the diaphragm, the thickness T1 of the first pole piece, the thickness T2 of the second pole piece, and calculate the spacing and width of the multi-electrode tabs, and die-cut according to the set data; Step 2: Wind the first pole piece, the separator and the second pole piece in sequence to obtain a multi-electrode wound battery cell.

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