Electrochemical impedance analysis of hydrogen storage alloy negative electrodes based on the porous electrode model

Electrochemical impedance method was applied to pasted-type negative electr odes (current collector: metal core sheet) of Ni-MH batteries. The followin g information was obtained during a charge-dis charge cycle test without di sassembling the batteries; 1) solution resistance, 2) contact resistance be tween particles of the active material, 3) impedance of the corrosion produ ct, 4) charge transfer resistance and capacitance of the electric double la yer at the interface between the electrolyte and the active material, 5) Wa rburg impedance caused by hydrogen diffusion in the active material. It was also clarified that the porosity of the electrode was very important to analyze impedance spectra measured by the pasted-type electrodes.