Flake Cu-Sn Alloys as Negative Electrode Materials for Rechargeable Lithium Batteries

Abstract

We have prepared the intermetallic compound using mechanical-alloying, gas-atomizing, and melt-spinning techniques. The electrochemical performance of the compound is critically dependent on its morphology due to different preparation methods. The alloy created by mechanical alloying, consisting of thick flake powder, has the best battery performance of all compounds. It delivers a rechargeable capacity of 200 mAh/g (2000 Ah/L) over 50 cycles when the cycled voltage range is restricted to 0.2-1.5 V. The effect of the mechanical-alloying time and Cu/Sn ratio on its battery performance was further investigated. The presence of excess Cu in alloy, relative to showed improved cyclability at the expense of capacity, whereas an excess of Sn resulted in poor cyclability. A lithium-ion cell based on a flaked Cu-Sn microcomposite alloy negative electrode and a 5 V positive electrode was assembled. The cell showed an average working voltage at 4.0 V and cycled well with a reversible capacity of ca. 200 mAh/g based on the pure Cu-Sn alloy when a cell was cycled between 3.5 and 4.6 V. © 2001 The Electrochemical Society. All rights reserved.