Electroplated Sn-Zn alloy electrode for Li secondary batteries

Sn-based compounds have attracted great attentions because of their larger specific capacity for Li secondary batteries. An electroplating method has been developed to prepare a Sn-Zn based alloy. The structure and electrochemical performance of as-plated and heat-treated electrodes have been investigated in detail. Experimental results show that Cu(6)Sn(5) phase and many voids were formed in plated film after heat-treatment. At the same time, the component of Zn was segregated, forming two Zn layers. This multilayer structure in electrode was beneficial to strengthen the contact between the plated film and Cu foil, and to relax the volume expansion during cycling, which improved the cyclability of electrode. The discharge capacity of the heat-treated electrode remained over 450 mAh g(-1) after 50 cycles, while that of as-plated anode decreased seriously to 25 mAh g(-1). The charge-discharge reaction mechanism of a heat-treated anode also changed due to the formation of Cu(6)Sn(5) phase in the plated film. These results show that electroplated Sn-Zn alloy film on Cu foil is a promising anode material with larger specific capacity and long cycle life for Li secondary batteries.