摘要
采用熔体快淬法制备了(Mg70.6Ni29.4)90Nd10的非晶贮氢合金带,用X射线衍射仪和高分辨电镜对该合金在充放电循环过程中的组织结构演变进行了动态跟踪。结果表明:(Mg70.6Ni29.4)90Nd10贮氢合金在充放电循环过程中由非晶态慢慢晶化为纳米晶,初生相NdMg2Ni9在循环过程中逐渐转化为Mg2Ni,α-Mg和Nd2H5相。电化学性能测试表明,由于微观结构的变化对其放电容量的影响过程分为3个阶段:首先是前两个循环的活化过程,在第3个循环达到放电容量最高值(580.5 mAh.g-1);接下来是放电容量显著降低的4～10个循环阶段;最后是放电容量保持稳定的11～20个循环。研究发现NdMg2Ni9相的存在和保持合金的非晶结构是提高镁基电极合金循环稳定性的重要因素。
The amorphous Mg-based hydrogen-storage alloy （MgT0.6Ni29.4）90Nd10 was prepared by melt-spinning. The phase structures of the ribbons before and after charge/discharge cycling were characterized by high-resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD） analysis, respectively. It was found that the amorphous structure crystallized step by step, the NdMg2Ni9 phase formed at beginning, and then gradually decomposed into Mg2Ni, α-Mg and Nd2H5 phases as hydrogenation/dehydrogenation proceeded. The following results of electrochemical property showed that the change process of discharge capacity for （Mg70.6 Ni29.4）90Nd10 amorphous alloy was divided into three stages. At first stage was the first two cycles of activation, and the discharge capacity reached the highest value （580.5 mAh·g^-1） in the third cycle, and then followed by the stage of significant reduce of the discharge capacity from 4 to 10 cycles, the final stage was the stable discharge capacity of 11 to 20 cycles. It was found that the existence of NdMg2Ni9 phase and to maintain a large number of amorphous structures were important factors to improve the cycle stability.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2011年第6期759-763,共5页
Journal of the Chinese Society of Rare Earths
基金
中国博士后科学基金(20100481299)
山东省博士基金(BS2009CL039)
山东省博士后创新基金(201003130)
山东省高校科技计划(J11LD03)资助
关键词
Mg—Ni—Nd系贮氢合金
微观结构
放电容量
非晶
稀土
Mg-Ni-Nd hydrogen-storage alloy
microstructure
discharge capacity
amorphous alloy
rare earths
