Patent ID: 7687188

Claim:
A sealed cell having a non-resealable safety valve structure, the sealed cell comprising: a cell can having an opening; an electrode body having a positive electrode, a negative electrode, and a separator for separating the positive electrode and the negative electrode, the electrode body housed in the cell can; an electrolytic solution housed in the cell can; and a sealing plate for sealing the opening of the cell can, the sealed cell wherein: the sealing plate has a valve structure that is thinner than a main body of the sealing plate serving as the safety valve, the valve structure broken as soon as pressure inside the sealed cell reaches or exceeds a predetermined value so as to permit a gas inside the sealed cell to be released outside the sealed cell; and the valve structure has a dome protruding toward an interior of the sealed cell, the dome having at a periphery thereof a break groove located on a surface of the sealing plate facing the interior of the sealed cell for facilitating the breakage of the valve structure.