DEVELOPMENT OF SLIVER-ZINC CELLS OF IMPROVED LIFE AND ENERGY DENSITY

THIS SBIR PROGRAM IS AIMED AT IMPROVING THE CYCLE LIFE AND ENERGY DENSITY OF SILVER-ZINC CELLS, IN GENERAL AND PARTICULARLY THOST USED IN NAVAL PROPULSION SYSTEMS. WE INTEND TO ACHIEVE THOSE OBJECTIVES BY IMPROVING THE NEGATIVE (ZN) ELECTRODE AND THE SEPARATORS, WHICH ARE RESPONSIBLE FOR MOST OF THE SYSTEMS SHORTCOMINGS. NEGATIVE ELECTRODE IMPROVEMENTS ARE AIMED AT LIMITING THE "SHAPE CHANGE" OR MIGRATION OF THE ACTIVE MATERIAL FROM THE TOP AND EDGES TO THE CENTER OF THE PLATES, CREATING A DEPLETION AND DENSIFICATION PROBLEM, WHICH REDUCES CELL CAPACITY BY 50% IN 50-150 CYCLES DEPENDING ON DESIGN AND MODEOF OPERATION. AN ADDITIONAL GOAL IS TO ELIMINATE THE FORMATION OF ZINC DENDRITES, WHICH MAY PERFORATE THE SEPARATORS CAUSING CELL FAILURE BY INTERNAL SHORTING. THESE IMPROVEMENTS CAN HE REALIZED BY THE INTRODUCTION OF NEWLY DEVELOPED ADDITIVES TO THE NEGATIVE ELECTRODE.SEPARATOR IMPROVEMENTS ARE AIMED AT SEVERAL GOALS: INCREASED CHEMICAL RESISTANCE (FOR LONGER LIFE), DECREASED THICKNESS (FOR HIGHER ENERGY DENSITY), AND LOW ELECTROLYTIC RESISTANCE (FOR BETTER VOLTAGE) ARE MOST DESIRED. WE ARE PROPOSING TO DEVELOP SEVERAL MATERIALS WHICH WEHOPE WILL ACHIEVE THESE GOALS. DEVELOPMENT WORK ON THE NEGATIVE ADDITIVES AND SEPARATORS AND TESTING OF CELLS CONTAINING THEM IS PLANNED.