貯氫合金電化學(xué)性能的影響
(浙江大學(xué) 材料與化工學(xué)院, 杭州 310027)
摘 要: 研究了V基固溶體型貯氫合金（TiV2.1Ni0.3和TiV2.1Ni0.5）與Cu粉進(jìn)行復(fù)合球磨處理對(duì)其相結(jié)構(gòu)及電化學(xué)性能的影響。X射線衍射和掃描電鏡分析表明，鑄態(tài)合金均由體心立方(bcc)結(jié)構(gòu)的V基固溶體主相和bcc結(jié)構(gòu)的TiNi基第二相組成；當(dāng)與Cu粉復(fù)合球磨處理后，合金均變成由V基固溶體主相和體心四方(bct)結(jié)構(gòu)的CuNi2Ti第二相組成，且合金顆粒的表面狀態(tài)發(fā)生改變。電化學(xué)測(cè)試表明，球磨處理后合金電極的最大放電容量增加了25~39 mA·h/g，100次循環(huán)容量保持率大幅提高，循環(huán)穩(wěn)定性得到顯著改善。結(jié)果表明，Cu粉復(fù)合球磨處理是通過(guò)同時(shí)改變V基合金的第二相成分和晶體結(jié)構(gòu)以及合金顆粒的表面狀態(tài)來(lái)改善合金的電極性能，這與其他傳統(tǒng)球磨方式僅通過(guò)改變合金的表面狀態(tài)來(lái)改善電極性能的作用機(jī)制有所不同。
關(guān)鍵字: 貯氫合金；V基固溶體；Cu粉復(fù)合球磨處理；相結(jié)構(gòu)；電化學(xué)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
