Patent ID: 6899978

Claim:
A rechargeable electrochemical cell which is subjected to multiple charging cycles and discharging cycles, each charging cycle having a charging portion corresponding to a gassing charge where a gas is generated in the rechargeable electrochemical cell and a charging portion below the gassing charge, the rechargeable electrochemical cell comprising; opposed positive and negative electrodes; an aqueous electrolyte in ionic contact with the electrodes for supporting current flow therebetween; and, deactivatable impeding means, disposed in the electrolyte and having a constituent thereof bonded to the negative electrodes, for forming a barrier for impeding the gassing charge, the deactivatable impeding means activated by the charging portion corresponding to the gassing charge and being deactivated by the charging portion below the gassing charge such that when activated, the deactivatable impeding means impedes the gassing charge to limit gas generation in the rechargeable electrochemical cell, and when deactivated, the deactivatable impeding means has substantially no charge limiting effect, the deactivatable impeding means being deactivated and having substantially no effect during the discharge cycle.