A new cathode material for sodium-ion batteries, the sodium vanadium bronze γ-Na 0.96 V 2 O 5 , is easily synthesized by chemical sodiation of the γ′-V 2 O 5 polymorph at room temperature. This low-cost soft chemistry route leads to fine particles with high purity and high crystallinity. The crystal features and morphology of the γ-Na 0.96 V 2 O 5 material have been characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. It exhibits a layered structure with orthorhombic symmetry (Pnma space group) isomorphic to that of the lithiated γ-LiV 2 O 5 bronze. This cathode material is evaluated by charge−discharge experiments. Promising electrochemical performance is outlined. A quantitative Na extraction process is observed at a high voltage of 3.4 V versus Na + /Na, and a reversible electrochemical behavior is demonstrated with an initial specific capacity of 125 mAh g −1 , which remains at 112 mAh g −1 after 50 cycles at C/5. The structural reversibility of the sodium extraction−insertion reaction in γ-Na 0.96 V 2 O 5 is demonstrated upon cycling. This new vanadium bronze competes with the well-known cathode materials for sodium-ion batteries such as NaNi 1/3 Mn 1/3 Co 1/3 O 2 and NaFePO 4 .

Low‐cost, easily processable, and environmentally friendly rechargeable aqueous zinc batteries have great potential for large‐scale energy storage, which justifies their receiving extensive attention in recent years. An original concept based on the use of a binary Li+/Zn2+ aqueous electrolyte is described herein for the case of the Zn/V2O5 system. In this hybrid, the positive side involves mainly the Li+ insertion/deinsertion reaction of V2O5, whereas the negative electrode operates according to zinc dissolution–deposition cycles. The Zn//3 mol L−1 Li2SO4–4 mol L−1 ZnSO4///V2O5 cell worked in the narrow voltage range of 1.6–0.8 V with capacities of approximately 136–125 mA h g−1 at rates of C/20–C/5, respectively. At 1 C, the capacity of 80 mA h g−1 was outstandingly stable for more than 300 cycles with a capacity retention of 100 %. A detailed structural study by XRD and Raman spectroscopy allowed the peculiar response of the V2O5 layered host lattice on discharge–charge and cycling to be unraveled. Strong similarities with the well‐known structural changes reported in nonaqueous lithiated electrolytes were highlighted, although the emergence of the usual distorted δ‐LiV2O5 phase was not detected on discharge to 0.8 V. The pristine host structure was restored and maintained during cycling with mitigated structural changes leading to high capacity retention. The present electrochemical and structural findings reveal a reaction mechanism mainly based on Li+ intercalation, but co‐intercalation of a few Zn2+ ions between the oxide layers cannot be completely dismissed. The presence of zinc cations between the oxide layers is thought to relieve the structural stress induced in V2O5 under operation, and this resulted in a limited volume expansion of 4 %. This fundamental investigation of a reaction mechanism operating in an environmentally friendly aqueous medium has not been reported before.