JP-2026061930-A5 -

Dates

Publication Date

20260507

Application Date

20240930

Description

Figure 2 is an unfolded view of the electrode winding 20. That is, Figure 2 schematically represents a part of the laminate S20 obtained by unfolding the electrode winding 20. The laminate S20 includes a positive electrode 21, a negative electrode 22, and a separator 23. In the laminate S20, the positive electrode 21 and the negative electrode 22 are laminated to each other via the separator 23. The separator 23 has, for example, two base materials, namely a first separator member 23A and a second separator member 23B. Therefore, the electrode winding 20 has a four-layer laminate S20 in which the positive electrode 21, the first separator member 23A, the negative electrode 22, and the second separator member 23B are laminated in that order. The positive electrode 21, the first separator member 23A, the negative electrode 22, and the second separator member 23B are all substantially strip-shaped members with the W direction as the short side and the L direction as the long side. Furthermore, in the configuration example of the first joint 61 shown in Figure 9A, the ratio of length 61L (a+1) to length 61La , 61L (a+1)/ 61La , is substantially equal to the ratio of length 61L (a+2) in the winding direction (θ direction) from the (a+1)th first folded portion 61B(a+1) to the (a+2)th first folded portion 61B (a+2) counting from the winding center, 61L (a+2)/ 61L (a+1). Specifically, the ratio of length 61L2 to length 61L1 (61L2)/(61L1) is substantially equal to the ratio of length 61L3 to length 61L2 (61L3)/(61L2), and the ratio (61L3)/(61L2) is substantially equal to the ratio of length 61L4 to length 61L3 (61L4)/(61L3). That is, {(61L2/61L1)}≒{(61L3/61L2)}≒{(61L4/61L3)} That's how it is. In particular, in the example configuration of the second joint 62 shown in Figure 10A, the length 62 Lb in the winding direction (θ direction) of the electrode winding body 20 from the (b+1)th second folded portion 62B(b+1) to the (b+1)th second folded portion 62B(b+1) counted from the winding center of the electrode winding body 20 is longer than the length 62 Lb in the winding direction (θ direction) of the electrode winding body 20 from the bth second folded portion 62Bb to the (b+1)th second folded portion 62B (b+1) counted from the winding center of the electrode winding body 20. Specifically, in the example configuration of the second joint 62 shown in Figure 10A, length 62L2 is longer than length 62L1 (62L1 < 62L2), length 62L3 is longer than length 62L2 (62L2 < 62L3), and length 62L4 is longer than length 62L3 (62L3 < 62L4). In other words, in the example configuration of the second joint 62 shown in Figure 10A, the dimensions of the second joint 62 in the winding direction (θ direction) gradually increase from the winding center side toward the winding outer circumference side. Furthermore, in the configuration example of the second joint 62 shown in Figure 10A, the ratio of length 62L (b+1) to length 62Lb , 62L (b+1)/ 62Lb , is substantially equal to the ratio of length 62L (b+2) in the winding direction (θ direction) from the (b+1)th second folded portion 62B(b+1) to the (b+2)th second folded portion 62B (b+2) counted from the winding center, 62L (b+2)/ 62L (b+1). Specifically, the ratio of length 62L2 to length 62L1, (62L2)/(62L1), is substantially equal to the ratio of length 62L3 to length 62L2, (62L3)/(62L2), and the ratio (62L3)/(62L2) is substantially equal to the ratio of length 62L4 to length 62L3, (62L4)/(62L3). That is, {(62L2/62L1)}≒{(62L3/62L2)}≒{(62L4/62L3)} That's how it is. <3. Variations> (First variation) Next, a secondary battery 1A, which is a first modified example of the secondary battery 1 of the above embodiment, will be described. Figure 13A is a plan view showing an example of the configuration of the first joint portion 61-1 between the upper end face 41 of the electrode winding body 20 and the positive electrode current collector plate 24 in the secondary battery 1A. Figure 13B is a schematic plan view showing an enlarged view of the first joint portion 61-1 shown in Figure 13A. In the first joint 61 of the above embodiment, the ratio of length 61L (a+1) to length 61La , 61L (a+1)/ 61La , is substantially equal to the ratio of length 61L (a+2)/61L(a+1) to length 61L(a+1) in the winding direction (θ direction) from the (a+1)th first folded portion 61B (a+1) to the (a+2)th first folded portion 61B (a+2) counting from the winding center. In contrast, in the first joint 61-1 of this modified example, the ratio 61L (a+1)/ 61La and the ratio 61L (a+2)/ 61L (a+1) are different. Specifically, the ratio of length 61L3 to length 61L2 (61L3)/(61L2) is greater than the ratio of length 61L2 to length 61L1 (61L2)/(61L1). In addition, in secondary battery 1A, the second junction 62 can have the same configuration as the first junction 61-1. (Third variation) Next, secondary batteries 1C-1 and 1C-2 will be described as third modifications of the secondary battery 1 of the above embodiment. Figure 15A is a