Nano-composites SnO(VOx) as anodes for lithium ion batteries

Nano-composites of SnO(V₂O₃) _x (x = 0, 0.25, and 0.5) and SnO(VO)_0.5 are prepared from SnO and V₂O₃/VO by high-energy ball milling (HEB) and are characterized by X-ray diffraction (XRD), scanning electron microscopy, and high-resolution transmission electron microscopy techniques. Interestingly, SnO and SnO(VO)_0.5 are unstable to HEB and disproportionate to Sn and SnO₂, whereas HEB of SnO(V₂O₃) _x gives rise to SnO₂.VO _x . Galvanostatic cycling of the phases is carried out at 60 mA g⁻¹ (0.12 C) in the voltage range 0.005–0.8 V vs. Li. The nano-SnO(V₂O₃)_0.5 showed a first-charge capacity of 435 (±5) mAh g⁻¹ which stabilized to 380 (±5) mAh g⁻¹ with no noticeable fading in the range of 10–60 cycles. Under similar cycling conditions, nano-SnO (x = 0), nano-SnO(V₂O₃)_0.25, and nano-SnO(VO)_0.5 showed initial reversible capacities between 630 and 390 (±5) mAh g⁻¹. Between 10 and 50 cycles, nano-SnO showed a capacity fade as high as 59%, whereas the above two VO _x -containing composites showed capacity fade ranging from 10% to 28%. In all the nano-composites, the average discharge potential is 0.2–0.3 V and average charge potential is 0.5–0.6 V vs. Li, and the coulombic efficiency is 96–98% after 10 cycles. The observed galvanostatic cycling, cyclic voltammetry, and ex situ XRD data are interpreted in terms of the alloying–de-alloying reaction of Sn in the nano-composite “Sn-VO _x -Li₂O” with VO _x acting as an electronically conducting matrix.