Polystor Corporation

Sean Thompson

Frank L Martucci

Steven T Mayer

James L Kaschmitter

Jung H Souh

Disclosed are safe, easy to manufacture prismatic cells having scored regions strategically located on portions of the prismatic cell can or cell header. When they are located on the cell can, the scored regions are provided on the side of the can, rather than on the bottom of the can as in other designs. The scored region may be located on a corner of one side of the side of the cell can. Scored regions so located tend to release excess pressure over a relatively narrow and easier to control pressure range. Similar benefits can be obtained by placing the scored region on a 'dished' header of a prismatic cell. Such dished header designs have a vertical lip around the perimeter of a substantially flat horizontal portion. The scoring may be provided near one of the ends of the header's substantially flat portion.

Overcharge safety vents on prismatic cells

A cell pressure control system is disclosed which includes a conductive frangible tab which tears in response to a defined pressure. The frangible tab is affixed at one position to a stationary member and at another position to a deflection member which deflects in response to increasing internal cell pressure. When the cell pressure increases to a dangerous level, the deflection member exerts sufficient pressure on the frangible tab to cause it to break. When the tab breaks, the cell goes to open circuit, thus reducing the danger of continued pressure build up. If the cell's internal pressure continues to increase even after the pressure contact is opened, a second stage of the pressure control mechanism may be activated. Specifically, a pressure rupturable region in the above-mentioned deflection member will rupture and release the cell's internal pressure.

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Dublin, CA, United States of America

Sean Thompson