Heat-Treatment Effects of V-Based Solid Solution Alloy with TiNi-Based Network Structure on Hydrogen Storage and Electrode Properties.

Abstract Heat-treatment at 973–1473 K was conducted on a V 3 TiNi 0.56 alloy which consisted of a V-based solid solution main phase for hydrogen storage and a TiNi-based secondary phase for electrochemical reaction. Heat-treatment at 1073 K was found to improve the durability during electrical charge-discharge cycles in NiMH cells because the corrosive vanadium content in the secondary phase was decreased by the heat-treatment. High-rate capability, however, was decreased by heat-treatment above 1273 K because of the increased grain size of the main phase and degradation of the TiNi-based network structure of the secondary phase.