The cell performance of both the vanadium oxide nanofibers with the δ-phase structure and the thermal product at 500 °C was studied. The δ-phase showed a capacity of just 110 mAh/g when discharged to 1.75 V, as shown in Fig. 3a; this capacity decayed even further on cycling. This is much lower than the ammonium analog, NH4V4O10, which also showed a low polarization [6]. However, the electrochemical properties were dramatically improved after heating the vanadium oxide nanofibers to 500 °C in air, forming single sheet V2O5. This V2O5 still showed the belt-shape morphology with dimensions less than 100 nm (Fig. 3b). This material showed the typical multi-step discharge behavior of crystalline V2O5[24], but as shown in Fig. 3c these steps are lost and a continuous cycling behavior is found as reported for ω-V2O5[24] and [25], where the lithium and vanadium ions have become randomized giving a rock-salt structure. The cell capacity is remarkably high, approaching 360 mAh/g in the first cycle, exceeding the 200 mAh/g typical of bulk V2O5[24]. The capacity is reversible and remains above 240 mAh/g for at least 25 cycles. However, there is a slight overcharge on each cycle, which we associate with reaction with the electrolyte. As observed for the reactive Mn3O4 anode material [2], this was solved by the addition of a small amount of LiBOB to the electrolyte, 5% LiBOB and 95% LiPF6, leading to a more effective protective layer [15] and [16]. Fig. 3d shows that the cycling efficiency is now close to 100%, but there is a loss in the capacity of the vanadium oxide. Higher levels of LiBOB were found to give even lower cell capacities and with usually lower efficiencies.