Self-discharge performance of Ni-MH battery by using electrodes with hydrophilic/hydrophobic surface

The polytetrafluoroethylene (PTFE) and carboxymethyl cellulose (CMC) film is separately coated on the surface of the metal hydride (MH) and Ni(OH)2 electrodes to obtain the electrodes with hydrophobic or hydrophilic surface. The effects of the surface treatment on the oxygen and hydrogen evolution from the electrodes are studied by using cyclic voltammetry tests. Although the positive and negative active materials of the Ni-MH batteries show a lower self-decomposition rate after the CMC treatment, the self-discharge rate of the batteries show little change. On the contrary, the self-discharge rate of the batteries decreases from 35.9% to 27.1% by using the PTFE-treated Ni(OH)2 electrodes, which might be related to the suppression of the reaction between NiOOH and H2 by the hydrophobic film.