Zn2SnO4 nanowires versus nanoplates: electrochemical performance and morphological evolution during Li-cycling.

Zn2SnO4 nanowires have been synthesized directly on stainless steel substrate without any buffer layers by the vapor transport method. The structural and morphological properties are investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of Zn2SnO4 nanowires is examined by galvanostatic cycling and cyclic voltammetry (CV) measurements in two different voltage windows, 0.005-3 and 0.005-1.5 V vs Li and compared to that of Zn2SnO4 nanoplates prepared by hydrothermal method. Galvanostatic cycling studies of Zn2SnO4 nanowires in the voltage range 0.005-3 V, at a current of 120 mA g(-1), show a reversible capacity of 1000 (±5) mAh g(-1) with almost stable capacity for first 10 cycles, which thereafter fades to 695 mAh g(-1) by 60 cycles. Upon cycling in the voltage range 0.005-1.5 V vs Li, a stable, reversible capacity of 680 (±5) mAh g(-1) is observed for first 10 cycles with a capacity retention of 58% between 10-50 cycles. On the other hand, Zn2SnO4 nanoplates show drastic capacity fading up to 10 cycles and then showed a capacity retention of 80% and 70% between 10 and 50 cycles when cycled in the voltage range 0.005-1.5 and 0.005-3 V, respectively. The structural and morphological evolutions during cycling and their implications on the Li-cycling behavior of Zn2SnO4 nanowires are examined. The effect of the choice of voltage range and initial morphology of the active material on the Li-cycleabilty is also elucidated.