Dual separator design for medical implantable electrochemical cells

An electrochemical cell comprises a casing having an open- ended container closed by a lid. An anode and cathode are housed inside the casing. The cathode housed inside a primary separator envelope is electrically connected to a positive polarity terminal pin electrically isolated from the casing by a glass-to- The anode is electrically connected to the casing metal seal.serving as a negative terminal. The primary separator enveloping the cathode is contained in a secondary separator comprising an open-ended bag-shaped member extending to an open annular edge. The open annular edge of the secondary separator resides between the cathode electrically connected to the terminal pin and the anode electrically connected to the casing. An electrolyte provided in the casing activates the anode and cathode.