NOVELTY - The electrochemical cell (20) has (1) a cylindrical container (22); (2) a cathode (24) having void (26) filled with cell ingredients (28); (3) an end plate; (4) an ionically permeable separator (30); (5) a negative current collector (32); (6) a compressed seal member which prevents flow of cell ingredients; and (7) a vent member which opens when internal cell pressure exceeds specific threshold.    USE - For power generation.    ADVANTAGE - The electrochemical cell has improved seal and vent mechanism that increases the usable internal volume of cell cavity. The seal and vent may be designed having properties that are compatible with their respective functions. The seal prevents leakage of internal cell ingredients into ambient environment during normal operation, while the vent provides internal pressure dissipation once the internal cell pressure exceeds maximum permissible threshold. The vent is closed to block an aperture extending through the end plate only when the internal cell pressure is below the specific threshold, and is opened to allow pressurized internal cell ingredients to escape from the cell when the internal pressure exceeds specific pressure.    DETAILED DESCRIPTION - The electrochemical cell has    (1) a cylindrical container having an axially extending sidewall;    (2) a cathode having an inner surface that defines a centrally disposed void filled with internal cell ingredients;    (3) an end plate which defines an extending aperture connected to the container;    (4) an ionically permeable separator interposed between the cell ingredients and the cathode;    (5) a negative current collector at least partially disposed within the void and electrically connected to the cell ingredients, where the current collector has a distal end that is connected to the end plate;    (6) a compressed seal member disposed between the end plate and the container, where the seal prevents the cell ingredients from flowing; and    (7) a vent member separate from the seal member providing a blockage to the aperture.    The vent opens when an internal cell pressure exceeds a predetermined threshold.    DESCRIPTION OF DRAWING(S) - The figure shows sectional view of negative terminal end of electrochemical cell.    Electrochemical cell (20)    Cylindrical container (22)    Cathode (24)    Void (26)    Cell ingredients (28)    Separator (30)    Negative current collector (32)    Seal and vent mechanism (60)