Rapid microwave-assisted synthesis strategy of dual-cationic molybdates as high-performance electrodes for alkaline battery-supercapacitor hybrid devices

Abstract

Metal molybdates have attracted considerable attention owing to the development and application of electrochemical energy storage materials and catalysts. However, a long reaction period is normally required during the preparation process of metal molybdates such as classic hydrothermal method. Herein, two groups of dual-cationic metal molybdates, CoxNi1−xMoO4 and CoxCa1−xMoO4 (0≤ x ≤1), were synthesized via a facile and rapid microwave-assisted method. The reaction time was shortened to 30 min via microwave irradiation. The additional redox reactions and increased pore structures induced by extra cation helped the dual-cationic metal molybdates to improve the capacity and extend the cycling span. The optimal electrode in each group was used as the positive electrode, and an active carbon (AC) electrode was used as the negative electrode to assemble the alkaline aqueous battery-supercapacitor hybrid (BSH) device, respectively. The two assembled BSH devices exhibited excellent application prospects and could achieve the highest energy density of 11.1 Wh kg−1 and 8.4 Wh kg−1, respectively. Apart from promising BSH devices, this research also provides a green and rapid synthesis strategy for fabricating other molybdenum-based materials for exceptional properties.