Abstract: In an electrochemical cell having a molybdenum terminal rod extending through a metallic housing, a feedthrough assembly for insulating the terminal rod from and bonding it to the housing. The assembly comprises an insulating body of aluminum nitride, yittria or mixtures thereof surrounding the rod. The terminal rod is welded to a molybdenum ring integrally bonded to the insulating body. Also integrally bonded to the insulating body is a second molybdenum ring, which is electrically insulated from the first ring and is employed to attach the insulator to the housing. In a preferred embodiment, the construction is employed in a lithium-iron sulfide cell to hermetically seal the terminal rod to the housing.