A lithium battery having a weldable feedthrough which is compatible with liquid electrolytes containing organic solvents and lithium salts under long term use conditions. The feedthrough comprises a pin of niobium or tantalum and ductile alloys thereof and a low silica insulating glass positioned around a portion of the pin in sealing engagement with the pin. The feedthrough is assembled into an aperture of the battery case where it provides an electrically conductive pathway from the anode or cathode to the exterior of the case and provides a hermetic seal.