A capacitor having at least two side-by-side anodes with a cathode current collector disposed between the anodes and housed inside a casing is described. Cathode active material is supported on the opposed major faces of the current collector and the current collector/cathode active material subassembly is housed in a first separator envelope. The first separator envelope is positioned between the side-by-side anodes and this electrode assembly is then contained in a second separator envelope. The two anodes can be connected in parallel inside or outside casing, or they can be unconnected to each other. There is also cathode active material supported on inner surfaces of the casing in a face-to-face alignment with an adjacent one of the anodes. That way, the second separator envelope also prevents direct physical contact between the anode pellets and the cathode active material supported on the casing sidewalls.

A capacitor having at least two side-by-side anodes with a cathode current collector disposed between the anodes and housed inside a casing is described. Cathode active material is supported on the opposed major faces of the current collector and the current collector/cathode active material subassembly is housed in a first separator envelope. The first separator envelope is positioned between the side-by-side anodes and this electrode assembly is then contained in a second separator envelope. The two anodes can be connected in parallel inside or outside casing, or they can be unconnected to each other. There is also cathode active material supported on inner surfaces of the casing in a face-to-face alignment with an adjacent one of the anodes. That way, the second separator envelope also prevents direct physical contact between the anode pellets and the cathode active material supported on the casing sidewalls.

An object is to obtain a power storage device which can prevent infiltration of a fluid such as water through a gas exhaust tube. A power storage device of the present invention includes a power storage case housing battery cells, a gas exhaust tube communicating between the interior and exterior of the power storage case, and an infiltration prevention mechanism unit preventing a fluid from passing through the gas exhaust tube and infiltrating from the exterior into the interior of the power storage case. The infiltration prevention mechanism unit includes a valve case having a flow path communicating between the interior and exterior of the power storage case, a valve body housed in the valve case and selectively movable to a closed position and an open position, and a guide member guiding the valve body movably in the fluid flow direction.

A cell balancing module according to an embodiment of the present invention comprises: a main board on which a plurality of cell balancing resistors are mounted; at least one sub-board on which a plurality of cell balancing resistors are mounted and which is formed above the main board while being spaced a predetermined distance apart therefrom; and at least one connector which supports the sub-board to be spaced apart from the main board and electrically connects the sub-board to the main board.

A capacitor is provided with a case having a receptacle with an expandable section that allows the receptacle to extend axially when internal pressure builds within the case as a result of a fault. Terminals are mounted on the cover and electrically connected to the electrodes of a capacitor element through an interrupter plate, via leads. The plate is attached to the section of the case that extends under pressure, whereby the plate is drawn away from the cover, thereby breaking the electrical connections to the terminal. The plate may also work in conjunction with a cover that expands outward in response to internal pressure, to provide a second pressure interrupter mechanism.

The invention concerns an electrical energy storage assembly (capacitor or battery) comprising: -an envelope (20) including: *at least one lateral wall (21), and *an open end, -an electrochemical element (30) intended to be contained in the envelope (20) and -at least one cover (40) intended to be positioned at the open end of the envelope (20), each cover (40) including: *a cover wall (41, 45) intended to cover the open end of the envelope (20), *a lateral face (42, 43) at the periphery of the cover wall (41, 45) and intended to be facing the lateral wall (21) of the envelope (20), -at least one electrically insulating elastic annular ring (50) intended to be positioned between the lateral wall (21) of the envelope (20) and the lateral wall (42, 43) of the cover (40).

The invention concerns an electrical energy storage assembly (capacitor or battery) comprising: -an envelope (20) including: *at least one lateral wall (21), and *an open end, -an electrochemical element (30) intended to be contained in the envelope (20) and -at least one cover (40) intended to be positioned at the open end of the envelope (20), each cover (40) including: *a cover wall (41, 45) intended to cover the open end of the envelope (20), *a lateral face (42, 43) at the periphery of the cover wall (41, 45) and intended to be facing the lateral wall (21) of the envelope (20), -at least one electrically insulating elastic annular ring (50) intended to be positioned between the lateral wall (21) of the envelope (20) and the lateral wall (42, 43) of the cover (40).

A housing having an overpressure protection includes a pressure relief opening with a diaphragm sealing plug to be closed in a fluid-tight manner. The diaphragm sealing plug has a central portion and an angled free peripheral portion. The free peripheral portion in the non-pressurized operating state extends away from the central portion in the direction of the housing external side. The central portion, by way of an increasing housing internal pressure in the axial direction, is deformable in such a manner that the peripheral portion by way of a tension stress that is derived from the deformation of the central portion in a manner proportional to the pressure is releasable from the housing wall in the axial direction in a progressive manner from the inside to the outside such that the diaphragm sealing plug releases the pressure relief opening when a predefined maximum housing internal pressure is reached or exceeded.

An object of the invention is to provide a hydrogen-releasing film which rarely undergoes the deterioration in hydrogen-releasing performance even when used for a long period. In addition, it is another object of the present invention to provide a safety valve for an electrochemical element, wherein the valve is provided with the hydrogen-releasing film, and to provide an electrochemical element having the safety valve. A hydrogen-releasing film having a metal layer, wherein at least one surface of the hydrogen-releasing film has a water contact angle of 85 or more.

An object of the invention is to provide a hydrogen-releasing film which rarely undergoes the deterioration in hydrogen-releasing performance even when used for a long period. In addition, it is another object of the present invention to provide a safety valve for an electrochemical element, wherein the valve is provided with the hydrogen-releasing film, and to provide an electrochemical element having the safety valve. A hydrogen-releasing film having a metal layer, wherein at least one surface of the hydrogen-releasing film has a water contact angle of 85 or more.