Abstract: In one embodiment, an energy storage device comprises a container containing a first electrode generating a positive charge, a second electrode generating a negative charge, and an electrolyte in ionic contact with the electrodes. The container comprises a base and one or more walls defining an opening in the container, the base having a first terminal in electrical connection with the first electrode. A cap is shaped to close the opening and is electrically isolated from the container, while having a second terminal in electrical connection with the second electrode. A collector plate is interposed between the first electrode and the base and is electrically conductive, providing the electrical connection between the first electrode and the first electrical terminal and exhibiting an extension with a concave side oriented in the direction of the base, which is connected to the base by interference fitting against a mating protrusion on the base.

Abstract: Porous separator is sandwiched between electrode films with attached current collector foil to obtain an electrode sheet. The electrode sheet is formed into a jellyroll for use in a double layer capacitor. The jellyroll is inserted into a can through an open end to rest against the can's bottom. A collector plate is pressed against the jellyroll, crunching current collector foil protruding from each end of the jellyroll. The bottom and the collector plate include indentations of reduced thickness. Laser is applied to the indentations to weld the foil on each end of the jellyroll to the bottom or collector plate. The laser application pattern, for example, a zigzag pattern, results in the total length of laser welds along each indentation being considerably longer than the length of the indentation, reducing contact resistance between (1) the foil and the bottom, and (2) the foil and the current collector.

Abstract: Porous separator is sandwiched between electrode films with attached current collector foil to obtain an electrode sheet. The electrode sheet is formed into a jellyroll for use in a double layer capacitor. The jellyroll is inserted into a can through an open end to rest against the can's bottom. A collector plate is pressed against the jellyroll, crunching current collector foil protruding from each end of the jellyroll. The bottom and the collector plate include indentations of reduced thickness. Laser is applied to the indentations to weld the foil on each end of the jellyroll to the bottom or collector plate. The laser application pattern, for example, a zigzag pattern, results in the total length of laser welds along each indentation being considerably longer than the length of the indentation, reducing contact resistance between (1) the foil and the bottom, and (2) the foil and the current collector.