贮氢合金电化学性能的影响
(浙江大学 材料与化工学院, 杭州 310027)
摘 要: 研究了V基固溶体型贮氢合金（TiV2.1Ni0.3和TiV2.1Ni0.5）与Cu粉进行复合球磨处理对其相结构及电化学性能的影响。X射线衍射和扫描电镜分析表明，铸态合金均由体心立方(bcc)结构的V基固溶体主相和bcc结构的TiNi基第二相组成；当与Cu粉复合球磨处理后，合金均变成由V基固溶体主相和体心四方(bct)结构的CuNi2Ti第二相组成，且合金颗粒的表面状态发生改变。电化学测试表明，球磨处理后合金电极的最大放电容量增加了25~39 mA·h/g，100次循环容量保持率大幅提高，循环稳定性得到显著改善。结果表明，Cu粉复合球磨处理是通过同时改变V基合金的第二相成分和晶体结构以及合金颗粒的表面状态来改善合金的电极性能，这与其他传统球磨方式仅通过改变合金的表面状态来改善电极性能的作用机制有所不同。
关键字: 贮氢合金；V基固溶体；Cu粉复合球磨处理；相结构；电化学性能
（ College of Materials Science and Chemical Engineering,
Zhejiang University, Hangzhou 310027, China）
Abstract: The influence of ball-milling with Cu powder on the phase structure and electrochemical properties of V-based solid solution type hydrogen storage alloys (TiV2.1Ni0.3 and TiV2.1Ni0.5) were investigated systematically. X-ray diffraction and scanning electron microscope analysis show that the as-cast alloys consist of V-based solid solution main phase and TiNi-based secondary phase with bcc structure. However, the alloys ball-milled with Cu powder are composed of V-based solid solution main phase and CuNi2Ti secondary phase with bct structure, and the surface shapes of the milled alloys are changed synchronously. The electrochemical measurements show that the maximum discharge capacities of the alloys ball-milled with Cu powder increase and the cycling stability is noticeably improved. As a result, the ball-milling with Cu powder influences the bulk crystal structure and the surface shape, which is quite different from traditional ball-milling.
Key words: hydrogen storage alloy; V-based solid solution; ball-milling with Cu powder; phase structure; electrochemical property
