球磨Mg0.97La0.03Ni合金的热稳定性及电性能研究

采用XRD、DTA、SEM及电池性能测试仪等对球磨Mg0.97La0.03Ni合金的结构、形貌、活化性能、热稳定性、电化学稳定性及容量衰减机理等进行了详细的研究。结果表明：样品的热稳定性及循环稳定性随着球磨时间的延长而增加。经400r／min球磨50h的样品在第二次活化时即达到最大值450mAh／g．经25次循环充放电后．该样品的容量与其最大值相比下降了53％．容量衰减的主要原因有：在循环充放电过程中．非晶体逐渐分解生成Mg2NiH4和Ni等晶体相，同时在颗粒表面形成腐蚀产物Mg(OH)2等。

The thermal stability and electrochemical characteristics of the Mg0.97La0.03Ni alloys prepared by ball milling

The structure, activation properties, thermal stability, electrochemical stability and the degradation mechanism of the discharge capacity of the Mg_(0.97)La_(0.03)Ni alloys prepared by ball milling were investigated by using the X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM) and the battery test apparatus. The results showed that the thermal and electrochemical stabilities would be improved by prolonging the milling time. The Mg_(0.97)La_(0.03)Ni alloys could reach their maximum electrochemical discharge capacities (about 450mAh/g) at the second charge/discharge cycle. The discharge capacity decreased 53 percent after the 25th charge/discharge cycles, and the degradation mechanism of the capacity was as following: the amorphous structure would decomposed to the crystalline Mg_2NiH_4 and Ni phases and the Mg(OH)_2 phase would formed on the surface of the particles during the charge/discharge cycling.