Electrochemical performance of a tin-coated carbon fibre electrode for rechargeable lithium-ion batteries

An Sn-carbon fibre composite electrode is fabricated by electrodepositing a thin film (0.5 +/- 0.1 mu m) of Sn with an ultrafine grain size (350 +/- 50 nm) on the 7.5 +/- 1.5 mu m diameter fibres of a carbon fibre paper (CFP). The electrochemical performance of the Sn-CFP composite being considered as an anode material for rechargeable Li-ion batteries is evaluated by conducting galvanostatic charge-discharge cycling tests. The Sn-CFP electrode displays a reversible planar capacity of 2.96 mAh cm(-2) with a capacity retention of 50% after twenty cycles, compared to the 23% measured for a 2.2 +/- 0.2 mu m thick Sn coating deposited on a Cu foil. The enhanced cycling performance of the Sn-CFP electrode is attributed to the double role played by carbon fibres, which act as randomly oriented current collectors in addition to being an active material. The small thickness and large surface area of the Sn coating on the carbon fibres enhances the coating's chemical reactivity and tolerance for volume change. It is suggested that transforming Sn to Sn oxides in Sn-CFP electrodes may improve the cycling performance of these composites as anode materials for rechargeable Li-ion batteries. (C) 2011 Elsevier B.V. All rights reserved.