Electrochemical characterization of novel layered Cu2MS4 materials for Li-ion batteries (M = Mo)

Abstract

Electrochemical performance of Cu2MoS4 was evaluated. When the cutoff potential is limited between 1.6 and 3.0 V. the material can give stable cycle performance of up to 100 mA hg(-1). However, the material shows slow kinetics within this region. The material can give a discharge capacity of up to 653 mA hg(-1) when discharged to 0.6 V vs. Li/Li+, with a first cycle efficiency of 61.3%. This corresponds to an insertion of 8.5 Li and an extraction of 5.2 Li from the material. XRD and XPS measurements both suggest Cu displacement from the material during discharge and charge, which is a possible reason for the poor cycle stability of the material. A reaction mechanism is proposed based on the XPS analysis. Better cycle performance is observed for Cu2MoS4/GO composite. (C) 2013 Elsevier Ltd. All rights reserved.