On the discharging process of titanium-based hydrogen storage alloy electrode via a.c. impedance analysis

An a.c. impedance technique is applied to study the frequency response during the discharging process of an electrode fabricated from titanium-based hydrogen storage alloy. Conditions are discussed under which either diffusion or adsorption of hydrogen control the overall electrode process. The impedance spectra obtained at different discharge states of the electrode reveal that the rate-determining-step (RDS) of the discharging process varies from an electrochemical process to diffusion of hydrogen along with the discharging of the electrode. The impedance spectra obtained at different temperatures of discharging also show a significant variation of RDS. A further understanding of the discharging process of titanium-based hydrogen storage alloy electrode is discussed.