A high-capacity and long-life aqueous rechargeable zinc battery using a metal oxide intercalation cathode

Although non-aqueous Li-ion batteries possess significantly higher energy density than their aqueous counterparts, the latter can be more feasible for grid-scale applications when cost, safety and cycle life are taken into consideration. Moreover, aqueous Zn-ion batteries have an energy storage advantage over alkali-based batteries as they can employ Zn metal as the negative electrode, dramatically increasing energy density. However, their development is plagued by a limited choice of positive electrodes, which often show poor rate capability and inadequate cycle life. Here we report a vanadium oxide bronze pillared by interlayer Zn²⁺ ions and water (Zn_0.25V₂O₅ṡnH₂O), as the positive electrode for a Zn cell. A reversible Zn²⁺ ion (de)intercalation storage process at fast rates, with more than one Zn²⁺ per formula unit (a capacity up to 300 mAh g^‑1), is characterized. The Zn cell offers an energy density of ∼450 Wh l^‑1 and exhibits a capacity retention of more than 80% over 1,000 cycles, with no dendrite formation at the Zn electrode.