Patent ID: 8003248

Claim:
An electrical energy storage device, which comprises: a) a container having a surrounding sidewall providing an opening leading into the container; b) an electrode assembly comprising an anode, a cathode and an intermediate separator disposed inside the container; c) a lid secured to the open end of the container to provide a casing housing the electrode assembly, the lid having: i) a thickness of from about 0.020 inches to about 0.050 inches extending between spaced apart upper and lower planar surfaces joined by a peripheral edge, ii) a transition surface forming a boss protruding from either the upper or the lower planar surface, wherein the transition surface has a frusto-conical shape extending at an angle greater than 90° to 160° from a first end of the transition surface at the one of the upper and lower planar lid surface to a second end of the transition surface connected directly to a planar shoulder, and iii) wherein the planar shoulder has a width of from one-half to five times the lid thickness and extends from the transition surface to an annular perimeter surface defining a bore extending through the boss to the other of the upper and lower planar surface thereof; d) a terminal lead connected to one of the anode and the cathode and extending through the bore to a position spaced above the upper surface of the lid; e) a glass in direct sealing contact with the terminal lead and the bore of the boss to thereby provide the terminal lead in an insulated relationship with respect to the casing; and f) an electrolyte provided in the casing to activate the anode and cathode electrodes.