V2.1TiNi0.4Zrx(x=0～0.06)储氢电极合金的相结构及电化学性能*

系统研究了V2.1TiNi0.4Zrx(x=0耀0.06)储氢电极合金的相结构及电化学性能. 相结构分析表明, 所有合金均由体心立方(bcc)结构的V 基固溶体主相和第二相组成, 且第二相沿主相晶界形成三维网状分布;其中, 当Zr 含量x 臆0.02时合金的第二相为TiNi基相, 而当Zr含量x达0.04时, 其第二相变为C14型Laves相, 且主相和第二相的晶胞体积均随着x 的增加而增大.电化学性能测试表明, 添加Zr 元素可以改善合金的活化性能和提高最大放电容量; 同时, 随着Zr 含量x 的增大, 合金的高倍率放电性能得到明显提高, 但充放电循环稳定性逐渐降低. 在所研究的合金样品中, V2.1TiNi0.4Zr0.04合金具有相对较好的综合性能.

Phase Structures and Electrochemical Properties of V2.1TiNi0.4Zrx (x=0～0.06) Hydrogen Storage Electrode Alloys

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.