V_3TiNi_(0.56)Al_(0.2)Cr_x(x=0～0.3)贮氢合金的微结构及电化学性能

Microstructure and electrochemical properties of V_3TiNi_(0.56)Al_(0.2)Cr_x(x=0～0.3) hydrogen storage alloys

采用自蔓延高温合成法制备V3TiNi0.56Al0.2Crx(x=0～0.3)贮氢合金,经XRD和电化学测试等研究Cr添加量对合金微结构及电化学性能的影响。结果表明:当x为0、0.1和0.2时,V3TiNi0.56Al0.2Crx合金均由V基固溶体主相和TiNi相组成;当x=0.3时,合金由V基固溶体主相和具有六方结构的C14型Laves相组成;随着Cr含量的增加,合金主相的晶胞常数和晶胞逐渐减小;添加Cr以后,合金电极的最大放电容量降低,对活化性能基本没有影响;此外,添加Cr可使合金循环性能得到明显改善,V3TiNi0.56Al0.2Cr0.3合金经过10次充放电循环后,容量保持率为99%,大电流放电性能最好;随着Cr含量的增加,合金中氢的扩散系数逐渐增大。

The V3TiNi0.56Al0.2Crx（x=0-0.3） hydrogen storage materials were prepared by self-propagating high-temperature synthesis.The influences of Cr content on the microstructure and electrochemical properties of these alloys were studied by X-ray diffraction and electrochemical measurement.The results show that when x are 0,0.1 and 0.2,the alloys are composed of V-based solid solution as main phase and TiNi phase.When x=0.3,the alloys are composed of V-based solid solution as main phase and laves phase of C14 with hexagonal structure.The unit cell constant and the quantity of unit cell both reduce gradually with increasing Cr addition.The maximum discharge capacity of the alloy electrode is decreased by introduction of Cr,whereas the activation behavior is almost not affected.The cycling capability of the alloys are improved obviously,the capacity of V3TiNi0.56Al0.2Cr0.3 alloy keeps 99% after ten times of charge,and discharge,and good discharge properties can be got under heavy current.The diffusion coefficient of hydrogen in the alloys increases with increasing Cr addition.