Thin films of Cu2Sb and Cu9Sb2 as anode materials in Li-ion batteries

Thin Cu2Sb films have been prepared by heat-treating Sb films. electrodeposited on Cu substrates. The influence of the electrodeposition conditions and the heat-treatment period on composition and morphology of the films were investigated (SEM and XRD) and the obtained films were tested as anode materials for Li-ion batteries. The Cu2Sb material showed a stable capacity of 290 mAh g(-1) (close to the theoretical capacity of 323 mAh g-1) during more than 60 cycles. The presence of 9-11% (w/w) Sb2O3 in the electrodeposited films resulted in smaller particles but also slowed down formation of Cu2Sb during the heat-treatment step. The presence of Sb2O3 was found to decrease the cycling stability although structural reversibility of Cu2Sb was obtained both with and without Sb2O3. Longer heat-treatment of pure Sb films resulted in the formation of Cu9Sb2 which was shown to be reduced at a lower potential than Cu2Sb. The Cu9Sb2 was converted to Cu2Sb during repeated cycling and the capacity of the latter Cu2Sb material was found to be 230 mAh g(-1). While reduction of the materials was complicated by simultaneous formation of an SEI layer, three plateaus Could be identified during the oxidation of Li3Sb, indicating the presence of three separate one-electron oxidation reactions. (c) 2008 Elsevier Ltd. All rights reserved.