Patent ID: 9281511
Filing Date: 2016-03-08
CPC Classification: H01M,Y02E,Y02P

Claim Text:
1. A battery cell comprising: at least one electrode assembly formed by flatly winding a band-shaped positive electrode and a band-shaped negative electrode stacked with a separator therebetween; a cell case in which the electrode assembly is housed; a positive-electrode external terminal structure arranged outside the cell case; a negative-electrode external terminal structure arranged outside the cell case; a first current collector electrically connected to a layer stack composed only of the band-shaped positive electrode and located on one end side of the electrode assembly in a width direction thereof, and electrically connected to the positive-electrode external terminal structure, the width direction being parallel to a winding axis of the electrode assembly; and a second current collector electrically connected to a layer stack composed only of the band-shaped negative electrode and located on the other end side of the electrode assembly in the width direction, and electrically connected to the negative-electrode external terminal structure, wherein a cross-section of the electrode assembly orthogonal to the winding axis has a short axis and a long axis, the first current collector is connected to any one of: part of both of a pair of positive-electrode layer stack sections; part of any one of the pair of positive-electrode layer stack sections; and the whole of any one of the pair of the positive-electrode layer stack sections, of the layer stack composed only of the band-shaped positive electrode, the pair of the positive-electrode layer sections extending in a direction of the long axis respectively in two regions bounded by a first virtual plane passing through the winding axis and the long axis of the electrode assembly, the second current collector is connected to any one of: part of both of a pair of negative-electrode layer stack sections; part of any one of the pair of negative-electrode layer stack sections; and the whole of any one of the pair of the negative-electrode layer stack sections, of the layer stack composed only of the band-shaped negative electrode, the pair of the negative-electrode layer stack sections extending in the direction of the long axis respectively in the two regions, a connecting location between the first current collector and the positive-electrode layer stack section and a connecting location between the second current collector and the negative-electrode layer stack section are set so as to be asymmetrical to each other with respect to a second virtual plane passing through a center of a width of the electrode assembly and being orthogonal to the first virtual plane and the winding axis, the width being a length of the electrode assembly in the width direction, a portion of the negative-electrode layer stack section located in a position symmetrical to the connecting location between the first current collector and the positive-electrode layer stack section with respect to the second virtual plane is held in an open state from one end to the other end in a direction of the short axis, and a portion of the positive-electrode layer stack section located in a position symmetrical to the connecting location between the second current collector and the negative-electrode layer stack section with respect to the second virtual plane is held in an open state from one end to the other end in a direction of the short axis.