An electrical energy storage device such as a wet tantalum electrolytic capacitor or an electrochemical cell such as a lithium/silver vanadium oxide cell is described. The enclosure comprises a drawn casing portion having a planar face wall supporting a surrounding sidewall and is shaped to nest the anode, cathode and intermediate separator components. A mating cover is a stamped planar piece of similar material having a periphery edge welded to the edge of the casing portion surrounding sidewall. In order to prevent heat generated during the welding process from damaging the separator, the anode portion adjacent to the weld site is contoured. This provides sufficient space between the weld and the separator supported on the anode at the contour so that what heat is transmitted to the separator by convection and conduction mechanism will not damage the separator.