Lithiation/delithiation performance of CU6Sn5 with carbon paper as current collector

Lithiation/delithiation of CU6Sn5 both electrochemically and mechanochemically prepared on a carbon paper (CP) current collector was investigated by repeated galvanostatic cycles with time-limited charges to insert different amounts of lithium per SO atom (Li/Sn) into the alloy. The results demonstrated that, unlike Cu6Sn5 electrodeposited on Cu foil, both electrochemical and mechanochemical Cu6Sn5 on CP can undergo hundreds of lithiation/delithiation cycles with Li/Sn > 2 at high current density (0.74 mA cm(-2)), thereby delivering constant amounts of charge with coulombic efficiency near 100%. The Cu6Sn5 /CP electrodes with a loading of 6.6 mg cm(-2) and charge limited to 2.43 Li/Sn yielded a specific capacity of 330 mAh g(-1) and a capacity per geometric area of 2.18 mAh cm(-2). These values compare well with those of graphite-based anodes of commercial batteries. The significant improvement in cyclability performance of the Cu6Sn5 /CP electrodes is due to the CP current collector's three-dimensional conductive matrix, which preserves the electric contact over cycling so that alloy cracking becomes less detrimental for the electric contact. (C) 2004 The Electrochemical Society. All rights reserved.