Spontaneous current and DC bias induced current in nickel-metal hydride secondary battery

The responses to biasing a nickel-metal hydride secondary battery with a dc pulse train, as well as to spontaneous discharging, are studied. A comparison is made between the current during biasing, i(e), and the current during off-biasing, i(g). It is suggested that both currents arise from the motion of the same charge carriers in the electrolyte., possibly the OH- ions. The only difference is that the motive force for i(e) is a bias voltage, while the motive force for i(g) is an open-circuit voltage of the battery. It is suggested that battery action proceeds by a single electrochemical reaction. In the course of discharging, the current drops abruptly by the formation of a resistive layer, possibly by depletion of the OH- ions in the vicinity of the positive electrode.