RE–Sn (RE = Y, Ce and Gd) alloys as anode materials for lithium-ion batteries†
Abstract
A series of rare earth (RE) metal doped tin-based RE–Sn alloys, Y–Sn, Ce–Sn and Gd–Sn have been successfully prepared by arc-melting and high energy ball milling techniques. X-ray diffraction and energy-dispersive X-ray spectroscopy confirm that the as-prepared RE–Sn alloys with an RE : Sn atomic ratio close to 1 : 3 have the same main phase of RESn3 corresponding to the AuCu3-type structure and the RE–Sn solid solution. As anode materials for lithium-ion batteries, the RE–Sn alloys exhibit enhanced specific capacity and cycling performance compared with the pure Sn anode. In particular, the Gd–Sn alloy exhibits the best cycling performance. A high initial discharge capacity of 787 mA h g−1 and a reversible capacity of 333 mA h g−1 are obtained after 40 cycles at a current density of 50 mA g−1. The improved cycling stability can be attributed to the buffer effect of Gd with good elastic properties. Based on the charge–discharge curves, cyclic voltammetry curves and ex situ XRD patterns, our experiments suggest that the lithium insertion/extraction mechanisms of RE–Sn alloys occur via a displacement mechanism.