NixCu6−xSn5 alloys as negative electrode materials for rechargeable lithium batteries

A series of Ni doped NixCu6−xSn5 (x = 0, 0.5, 1, 2, 4) alloys were prepared by mechanical alloying, followed by annealing at 400 °C. The Ni doped alloys show the similar structure with that of Cu6Sn5 and Ni3Sn2, which can be indexed to a hexagonal Ni2In type cell, but differ in the electrochemical performance as the anodes of Li-ion batteries. The electrochemical tests show that the cycling reversibility of NixCu6−xSn5 increases at the expense of the reversible capacity with the increasing amount of Ni content. The proper amount Ni doped alloy, Ni2Cu4Sn5 showed better cycle performance with a reversible capacity of 200 mAh g−1 (1680 mAh ml−1). The relative stability of the alloy was also investigated using the first-principles density-functional theory with pseudopotentials and plane wave basis (VASP).