IntroductionLithium-ion batteries (LIBs) are urgently needed as one of the most important energy storage devices have been broadly studied in recent years. 1 To build a high-quality lithium ion battery (LIBs), several factors should be taken into account, including energy density, rate capability, lightweight, cost, safety, environmental friendliness, natural abundance 2,3and sustainability. 4–9 There has been an intensive search interest to achieve this goal on the new cathode and anode materials with promising energy storage electrochemical performance. 10–16 In the case of anode materials, concerns about the long-term availability of a few elements have naturally driven researchers toward vanadium, titanium, iron, and copper. 17–22 Moreover, the facile and energy-saving material synthesis, rich structural chemistry, and multiple valence bonding states of vandadium-based materials have stimulated a great effort toward the development of high energy saving vanadium-based electrode materials, including metal vanadate’s 23,24 and V 3 O 7 , 25 V 6 O 13 , 26,27 V 2 O 5, 28–30 VO 2 31–33.V2O5 is one of the primary transition metals and also frequently studied both as anode and cathode for LIBs.
If consider a full reduction state from V5+ to V0, V2O5 gains a theoretical capacity of 1472 mAhg?1, among all metal oxides, and thus can be an ideal material for preparing high energy anodes for LIBs 19–22. It is generally accepted that vanadium-based oxide materials have a comparatively strong vanadium-oxygen bond which reacts with lithium through the insertion/de-insertion reaction, 34,35. Graphite is the most successful commercially used conventional anode material for LIBs, but can deliver only a low theoretical capacity of 372 mAhg1, so it cannot meet the ever growing demands for high energy density.36, 37 On the other hand, as another important energy storage technology is Na-ion batteries (NIBs). NIBs have attracted more and more attention owing to the abundance and low cost of the Na source.7, 8 Unfortunately, the radius of Na ions is larger than that of Li ions so that the number of available and high-performance anode materials for NIBs is still limited, so the majority of successful anode materials for LIBs, such as commercial graphite, are not suitable for NIBs.9, 10 Therefore, there is also an urgent need to find new and readily available anode materials for NIBs.