Performance improvement of Sn–Co alloy film anodes for lithium-ion batteries

Abstract

Three sets of Sn – Co alloy films were electrochemically deposited onto nodule-type Cu foil in aqueous solution. The results of X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) proved that the electrochemical current density and the depositing time had influence on the structure and the morphology of the alloy films. The electrochemical properties of the Sn – Co alloy film electrodes for lithium-ion battery were investigated by galvanostatic charge-discharge test and cyclic voltammetry (CV). The Sn – Co alloy with the thickness of 0.8 μm created at the current density of 15 mA cm-2 presents excellent electrochemical performance with the discharge capacity of 949.3 mAh g-1 at the first cycle and 661.1 mAh g-1 after 70 cycles. The high coulombic efficiency of almost 100% can be observed at different current rate. The improved performance is attributed to the structure of Cu foil, the optimized Co content and thickness of the alloy film, which were beneficial to strengthen the adhesion of the active materials to the current collector, shorten diffusion length of lithium ions and reduce the electrical resistance.