Electrochemical performances of Cu6Sn5-modified Sn anode with multi-layer structure for Li-ion cell

Abstract

To better understand the influence of morphology and structure on the electrochemical performance of the anode materials, thick Sn film was prepared by pulse electrodeposition on Cu substrate and Cu₆Sn₅-modified Sn film was formed with a facile method by post deposition heat treatment of Sn film at 232 ± 2 °C in argon for 12 h. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the composition and morphology of Cu₆Sn₅-modified Sn film. The Cu₆Sn₅-modified Sn film was directly assembled in Li-ion coin cells as the anode and studied by charge/discharge and AC impedance. A thick Sn film was used as the control to compare its electrochemical performances with Cu₆Sn₅-modified Sn film. The Cu₆Sn₅-modified Sn anode is a multi-layer structure with unique morphology of a surface continuous layer and a micron-crystalline layer, and exhibited strong correlation between cyclic properties and its structure as well as morphology. The Cu₆Sn₅-modified Sn anode showed increased capacity compared with the Sn anode. The micro-crystallite layer displayed the highest capacity and capacity retention.