Defect-Rich MoO_3–<i>X</i> Nanobelts toward High-Performance Anodes for Aqueous Aluminum Ion Batteries

The utilization of flammable organic electrolytes for electrochemical energy storage is likely to be expensive and results in unsafe conditions. The aqueous metal ion energy storage devices have recently been investigated and explored. Among these devices, the aqueous rechargeable aluminum ion batteries have potential because of a small ion radius, excellent redox properties of Al3+, safety, and low cost. In this case, MoO3–X nanobelts with rich oxygen vacancies have been prepared by etching PH3 gas generated from the decomposition of NaH2PO2·H2O. The MoO3–X nanobelt electrode obtains a higher capacity of 154.5 mAh g–1 with higher cycle stability in the AlCl3 electrolyte in comparison with 82.8 mAh g–1 for general MoO3 nanobelts. The MoO3–X nanobelts have increased interplanar space, more sufficient micro/mesopores with a disordered structure, thus enhancing the high capability of Al3+ storage in terms of both intercalation and adsorption. This study suggests a strategy of introducing oxygen vacancies into transition metal oxides to promote their ion storage capabilities. This work is expected to synthesize other desirable metal-oxide-based anodes for high Al3+ storage in aqueous solution.