INFLUENCE OF RECHARGE POTENTIAL AND ACID CONCENTRATION ON THE DISCHARGE BEHAVIOR OF PBO2 ELECTRODES

During the recharge of PbO2 electrodes, the electrode single potential and the acid concentration within its porous system usually changes over a wide range. A potentiostat and the Eloflux technique of forced flow-through of the electrolyte has been applied to keep these parameters homogeneous over all of the electrode for the whole period of recharge. A distinct dependence of the discharge capacity at a given rate on potential and acid-concentration conditions of the proceeding recharge has been found. Low recharge potentials and low acid concentration lead to a reversible capacity decay, while high potentials and high acid concentration may recover a previous capacity loss. This is in agreement with previous findings without forced flow-through of the electrolyte, where cycling with low initial recharge current densities induced a reversible capacity decay that reversed (or prevented) when recharge was performed with a high initial current density. These results support the 'Kugelhaufen' model which describes the reversible insufficient mass utilization (RIMU).