Zr_(0.8)Ti_(0.2)(Ni_(0.6)Mn_(0.2)V_(0.2)Cr_(0.05))_x贮氢合金结构和电化学性能的研究

Structural and Electrochemical Properties of the Hydrogen Storage Alloys Zr_(0.8)Ti_(0.2)(Ni_(0.6)Mn_(0.2)V_(0.2)Cr_(0.05))_x

研究了Zr0.8Ti0.2(Ni0.6Mn0.2V0.2Cr0.05)x(x=1.8～2.4)贮氢合金中化学计量x对晶体结构和电化学性能的影响。结果表明:随着x值的增大,合金中C14相含量逐渐减少,C15相含量逐渐增加,C14和C15相的晶格常数均线性减小;随着x值的增大,合金电极的活化性能提高,高倍率放电性能和放电容量均先升高,至x=2.2时达到最大值(最大放电容量为370mAh/g);超化学计量合金电极的循环寿命随x值的增大而降低,但当x<2.2时,经充放电循环500次以后容量保持率仍在80%左右。当化学计量值x等于2.2时,合金电极的综合电化学性能最好。

We studied a series of Zr0.8Ti0.2(Ni0.6Mn0.2V0.2Cr0.05) (x) alloys (x = 1.8 similar to 2.4) in order to reveal the effects of the stoichiometry on the phase structures and electrochemical properties. It was found that Zr0.8Ti0.2 (Ni0.6Mn0.2V0.2Cr0.05). alloys consist of C14 and C15 Laves phase, and secondary phase Zr7Ni10 or TiNi. With increasing x value, abundance of C14 phase decreases and C15 phase increases. Increase of x value leads to decrease of the lattice parameters of both C14 and C15 phases. As the x value increases the activation property, the discharge capacity and the high rate dischargeability are improved and the highest capacity is found for x = 2.2, (370 mAh/g). For the over - stoichiometrical alloys, the cycling stability is deteriorated with increasing of x value. A critical x value is found at x 2.2, and Zr0.8Ti0.2(Ni0.6Mn0.2V0.2Cr0.05)(2.2) alloy shows the best comprehensive electrochemical performances.