The deterioration behavior of a metal hydride electrode based on the V0.66Ti0.22Ni0.12 alloy

The deterioration behavior of a V0.66Ti0.22Ni0.12 alloy electrode during charge-discharge cycling in KOH electrolyte and its degradation mechanism were investigated. The alloy electrode was completely deteriorated within 10 cycles. Coating the alloy particles with Ni or Cu improved to some extent the cycle life but the capacity for decay with cycling was still significant. The capacity for loss of the V0.66Ti0.22Ni0.12 alloy electrode with cycling was ascribed to the dissolution of V and Ti (mainly V) from the near-surface region into the electrolyte and the formation of TiO2 layer on the alloy particle surface which resulted in increases of the contact resistance between particles and the reaction resistance on the alloy surface.