Lithiation/delithiation performance of Cu6Sn5 with carbon paper as current collectors

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 Sn 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 lithiathion/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 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 for geometric area of 2.18 mAh cm-2, which compare well with the values of graphite-based anodes of commercial batteries. The significant improvement on cyclability performance of the Cu6Sn5/CP electrodes is due to the carbon paper 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.