Abstract: The phase structures and electrochemical properties of the　V2.1TiNi0.4Zrx (x =0 ～0.06) hydrogen storage　electrode alloys have been investigated. It is found that all the alloys consist of a main phase of V－based solid solution　with a bcc structure and a secondary phase with a three－dimensional network structure. The secondary phase　precipitates along the grain boundaries of the main phase. For the alloys with Zr content x＝0.02, the secondary phase is the TiNi－based phase. As x reaches 0.04, the secondary phase changes into the C14－type Laves phase. Moreover, the　unit cells of both the main phase and the secondary phase expand with the increasing Zr content. Electrochemical　measurements show that activation behavior and maximum discharge capacities of the Zr－added alloy are better than　those of V2.1TiNi0.4 alloy. As the Zr content in the alloy increases, their high－rate dischargeability is improved　significantly, but their cycle stability degrades gradually. For the alloy with the Zr content of x=0.04, the best overall　electrochemical performances are obtained.

Key words: Hydrogen storage electrode alloy, Phase structure, Electrochemical property, V-based solid solution