Influence of Cr or Co doping on electrode properties of V2.1TiNi0.5Hf0.05 hydrogen storage alloy
(College of Materials Science and Chemical Engineering, Zhejiang University,
Hangzhou 310027, China)
Hangzhou 310027, China)
Abstract: The microstructures and electrode properties of Cr or Co-doped V2.1TiNi0.5Hf0.05M0.113 (M=Cr, Co) hydrogen storage alloys were investigated. It is found that all alloys consist of a main phase of V-based solid solution with b.c.c. structure and a secondary phase of C14-type Laves phase with a three-dimensional network structure. After the doping of Cr or Co into V2.1TiNi0.5Hf0.05, the abundance and unit cell volume of the main phase decrease, and those of the secondary phase increase. The electrochemical measurements show that the discharge capacities of Cr-doped V2.1TiNi0.5Hf0.05Cr0.113 alloy and Co-doped V2.1TiNi0.5Hf0.05Co0.113 alloy are less than that of V2.1TiNi0.5Hf0.05 alloy, but their cycle stability and high-rate dischargeability are improved markedly. The results show that Cr or Co doping into V2.1TiNi0.5Hf0.05 alloy is significantly beneficial for the cycling stability.
Key words: V-based hydrogen storage alloys; Cr doping; Co doping; electrode properties; microstructure