Patent ID: 8741477

Claim:
A bipolar secondary battery comprising: a plurality of bipolar electrodes stacked in a stacking direction, each bipolar electrode including a current collector with a first active material layer formed on a first surface of the current collector and the first active material layer having outer edges, and a second active material layer formed on a second surface of the current collector opposite the first surface and the second active material layer having outer edges; electrolyte layers disposed between the first active material layer and the second active material layer of immediately-adjacent pairs of bipolar electrodes of the plurality of bipolar electrodes; and a plurality of seal members, each disposed between the current collectors of each immediately-adjacent pairs of bipolar electrodes and about an outer periphery of the electrolyte layer in order to prevent leakage of an electrolyte solution of the electrolyte layers; wherein the outer edges of the first active material layers are positioned further from a center of the battery in a planar direction than the outer edges of the second active material layers, the planar direction being perpendicular to the stacking direction of the plurality of bipolar electrodes; and wherein each of the seal members includes a first edge portion and a second edge portion, the first edge portion having an inner surface facing an outer edge of the first active material layer and the second edge portion having an inner surface facing an outer edge of the second active material layer, and the second edge portion extending closer to the center of the battery in the planar direction than the first edge portion such that the second edge portion is overlapping the outer edge of the first active material layer in the stacking direction with the current collector provided therebetween.