Smart construction of MnCo2O4 microspheres with multiple interiors: Morphological evolution and structure-performance relationship for supercapacitor electrodes

Abstract

The development of a simple and general approach for manufacturing complex hollow structures is essential to achieve rapid dynamic response and high energy density storage for supercapacitor electrodes. Herein, we report a versatile heating rate-controlled synthetic route to prepare MnCo2O4 microspheres with multiple interiors. Comparative study reveals that MnCo2O4 microspheres with core–shell structure (MCO-CSS) process the highest specific surface area (91.6 m2 g−1) and oxygen vacancy density (0.16), which can provide more electroactive sites for surface Faradic reaction and further facilitate the kinetics of rapid charge storage. While the porous shell and well-defined gap endow MCO-CSS with excellent permeability and low-resistance pathways for electrolyte ions, as well as enhanced volume change accommodation. Benefiting from the structural advantages, MCO-CSS displays an excellent specific capacitance of 1064.4F g−1 at 1 A g−1, remarkable rate capability, and satisfactory cycle stability (89.1% capacitance retention at 2 A g−1 over 1000 cycles). Additionally, an asymmetric supercapacitor device, with an MCO-CSS cathode and porous carbon spheres anode, delivers a remarkable energy density of 33.9 Wh kg−1 at a power density of 187.4 W kg−1, as well as 84.13% capacitance retention over 3000 cycles at 1 A g−1.