RE贮氢合金充放电过程的原位XRD观测  

In situ X-ray diffraction observation on R.E.-based hydrogen-storage-alloy electrode during initial charge/discharge cycles

作　　者：王超群[1] 郑青军[1] 王宁[1] 邢政良[1] 李国勋[1] 

机构地区：[1]北京有色金属研究总院,北京100088

出　　处：《电源技术》2000年第2期94-96,共3页Chinese Journal of Power Sources

基　　金：国家自然科学基金资助项目! ( 5 95 710 2 0 )

摘　　要：采用原位X射线衍射 (XRD)观测稀土贮氢合金在初始充放电过程的结构变化。在第 1周期以 1 5 0mA/ g充电 1 6 5min ,贮氢合金的谱线发生宽化 ,但无明显的结构相变 ;在第 2周期充电 1 2h发生α→β转变 ,合金电极处于平台区 ,5 0mA/ g放电至 - 0 .6V时出现新的氢化物相即γ相 ,它是α/ β相界面内应力产生的 ;在第 3周期充电后γ相先是增加 ,然后减少 ,放电后 β相含量减少 ,γ相渐渐消失。稀土贮氢合金在初始几周充放电过程中的相结构转变机制与氢压下的活化机制相似 。The transition of phase constituent of R.E. based hydrogen storage alloy electrode during initial charge/discharge cycles were observed by means of in situ X ray diffraction. In the first cycle, the electrode was charged at 1500 mA/g for 165 min and the broadening of diffraction lines was observed while there were no phase transition existed. In the second cycle, the phase constituent of the alloy transited from α phase to β phase after being charged at 150 mA/g for 12 h when it was at the reaction plateau. A new hydride, the γ phase hydride, was produced when the electrode was discharged to -0.6 V at 50 mA/g. The γ phase hydride is considered to be a metastable phase that exists only in the presence of lattice strain around the interface between α phase and β phase. After the third cycle, the amount of γ phase hydride increased at first and then gradually decreased up to disappearance after being discharged at 50 mA/g as well as the decrease of the content of β phase. The results show that the transition mechanism of the phase constituent of R.E. based hydrogen storage alloy electrode during initial charge/discharge cycles is similar to its activation mechanism at hydrogen atmosphere. However, the two mechanism are not same completely.

关 键 词：稀土贮氢合金 充放电过程 XRD观测 MH-NI电池 

分 类 号：TG139.7[一般工业技术—材料科学与工程] TM912.2[金属学及工艺—合金]