The application of Zn-Al-hydrotalcite as a novel anodic material for Ni-Zn secondary cells

摘要

ZnAl-CO_3 layered double hydroxides (LDHs) are prepared by the constant pH co-precipitation method in this study and proposed as a novel anodic material for Nickel-Zinc secondary cells. The as-prepared samples are well-crystallized and have the plate-like morphology. It is shown that the reversibility of the electrode reaction of the ZnAl-hydrotalcites is much better than that of ZnO electrode in alkaline system probably due to the lamellar structure of ZnAl-hydrotalcites and the presence of aluminum ions. In spite of a little lower specific capacity, Zn-Al-hydrotalcite electrode has more stable cycling performance, higher charge efficiency and utilization ratio in comparison with ZnO electrode. The effect of Zn/ Al molar ratio on the electrochemical performance is investigated and ZnAl-hydrotalcites with Zn/Al molar ratio of 4:1 exhibit the best performance. It delivers an initial discharge capacity of 400 mAh g~(-1) and the capacity retention ratio of 92.7% over 50 cycles. This proves that ZnAl-hydrotalcites electrode is more stable than ZnO electrode in alkaline electrolyte, thus resulting in much better cycling stability.