V_(2.1)TiNi_(0.4)Zr_(0.06)Cu_(0.03)M_(0.10)(M=Cr,Co,Fe,Nb,Ta)储氢合金的微结构及电化学性能

Microstructure and Electrochemical Properties of V_(2.1)TiNi_(0.4)Zr_(0.06)Cu_(0.03)M_(0.10)(M=Cr, Co, Fe, Nb, Ta) Hydrogen Storage Alloys

采用磁悬浮感应熔炼方法制备了V2.1TiNi0.4Zr0.06Cu0.03M0.10(M=Cr,Co,Fe,Nb,Ta)储氢电极合金,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、电子衍射能谱(EDS)分析和电化学测试等手段系统研究了添加元素M对合金微结构与电化学性能的影响.结果表明,所有合金均由BCC结构的V基固溶体主相和C14型Laves第二相组成,且第二相沿主相晶界形成三维网状分布;Cr、Nb和Ta元素主要分布在合金主相中,而Co和Fe元素主要分布在第二相中.电化学性能测试表明,在V2.1TiNi0.4Zr0.06Cu0.03合金中掺加Cr、Co、Fe、Nb或Ta元素后,虽然会降低最大放电容量,但能有效抑制合金中V和Ti的腐蚀溶出,提高电极充放电循环稳定性;同时还能明显改善合金的高倍率放电性能.相比之下,V2.1TiNi0.4Zr0.06Cu0.03Cr0.10合金具有最佳的综合电化学性能.

V2.1TiNi0.4Zr0.06Cu0.03M0.10（M=Cr, Co, Fe, Nb, Ta） hydrogen storage alloys were prepared by induction melting with magnetic levitation. The effects of an additive element M on the microstructure and electrochemical properties of these alloys were investigated by means of X-ray diffractiuon （XRD）, scanning electron midroscopy（SEM）, electron diffraction spectroscopy （EDS） analyses and electrochemical measurements. The results show that all these alloys consist of a V-based solid solution main phase with bcc structure and a Cl4-type Laves secondary phase in the form of a three-dimensional network. Cr, Nb or Ta predominantly exist in the main phase and Co or Fe is mainly distributed in the secondary phase. Adding Cr, Co, Fe, Nb or Ta into the V2.1TiNi0.4Zr0.06Cu0.03 alloy can effectively restrict the dissolution of vanadium and titanium as well as improve the corrosion resistance and cycling stability of the alloy electrode. The maximum discharge capacity of the alloy, however, decreases to some extent. Doping with Cr, Co, Nb or Ta increases the high-rate dischargeability of the alloy. Among the alloy samples studied, the V2.1TiNi0.4Zr0.06Cu0.03Cr0.10 alloy possessed the best overall electrochemical properties.