Zr系贮氢合金晶体结构与电极特性间关系

ＡＢ２型Ｌａｖｅｓ相ＺｒＣｒ（０．４）Ｍｎ（０．２）Ｖ（０．１）Ｎｉ（１．３）贮氢合金经球磨非晶化处理后，相同化学成分的贮氢合金电极容量锐减，合金的晶体结构与其电化学放电容量密切相关．在晶态合金中，主要是Ｚｒ２Ｂ２（Ｂ＝Ｃｒ，Ｍｎ，Ｖ，Ｎｉ）四面体间隙的氢对电化学放电容量作出贡献，而在非晶态合金中，则是Ｚｒ３Ｂ，Ｚｒ４四面体间隙的氢．由于静电作用，都只有一半的间隙位置能容纳氢原子．非晶化处理导入额外的能量，以致降低合金中氢的电化学反应激活能．

RELATIONSHIP BETWEEN CRYSTAL CHARACTERISTICS AND ELECTROCHEMICAL PROPERTIES OF Zr BASED HYDROGEN STORAGE ALLOY

The electrochemical discharge capacity is in close relation with its crystal characteristics of AB2 type Laves phase hydrgoen storage alloy ZrCr0.4 Mn0.2V0.1Ni0.3, its capacity decreased shapoly from 324 mA · h / g to 25 mA · h / g after amorphization by mechanical milling of the crystalline (as-cast) alloy with stainless steel balls. Hydrogen atoms stored in the Zr2B2(B=Cr, Ni or V) tetrahedral interstitial sites of as-cast alloy lattice mainly contributed to its electrochemical capacity. However, for the amopohous alloy with the same composition the contribution to the electrochemical capacity is mainly resulted from the hydrogen atoms in Zr3B and Zr4 sites. It is believed that only haif sites in the crystilline or amorphous alloys can adsorb and desorb hydrogen atoms reversely. Extra energy induced during milling process can reduce the potential of electrochemical discharging of hydrogen reaction. Correspondent: YANG Xiaoguang, lecturer, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027