Hexagonal MoO3 as Zinc Intercalation Anode towards Zinc Metal-Free Zinc-Ion Battery

Aqueous rechargeable zinc-ion batteries (ZIBs) are attractive candidates in energy storage technology. However, the formation of Zn dendrite at potential close to the Zn/Zn2+ redox potential can severely limit the battery rechargeability and energy density. Herein, hexagonal MoO3 (h-MoO3) is proposed as an intercalation anode (discharge potential of 0.36 V (vs Zn2+/Zn)) as a potential replacement to the Zn metal plate for the first time, which showed a specific capacity of 120 mAh g−1 at 0.2 A g−1 with superior cyclic stability. Furthermore, the zinc metal-free full cell was successfully demonstrated by this h-MoO3 anode and Zn0.2MnO2 cathode. The cell delivered a specific capacity of 56.7 mAh g−1 which corresponds to an energy density of 61 Wh kg−1 (based on the total mass of anode and cathode materials), higher than most aqueous zinc ion batteries. Furthermore, excellent cyclic life was recorded as the full ZIB cell achieved ca. 100 % of its original capacity after 1000 cycles. Based on the preliminary investigation of utilizing h-MoO3 as ZIB anode, the results have shown significant promise in the feasibility of achieving Zn ion full batteries for energy storage applications.