Design and synthesis of Ni-Co and Ni-Mn layered double hydroxides hollow microspheres for supercapacitor

Abstract

The development of electrode materials with hierarchically porous structure and high electrochemical stability is crucial for the electric energy density of supercapacitors. Hollow microspheres of Ni-Co layered double hydroxides (LDHs) and Ni-Mn LDHs are fabricated with a simple co-precipitation method at low temperature using SiO2 microspheres as a sacrifice template. The as-fabricated two LDH hollow microspheres possess a unique 3D architecture and exhibit high specific capacitance, as well as excellent rate and cycling performances as electrode materials of supercapacitors. A specific capacitance of 1766.4 F g−1 at 1 A g−1 is achieved for Ni-Co LDHs electrode, much higher than that of Ni-Mn LDHs. A hybrid capacitor composed of Ni-Co LDHs hollow spheres and activated carbon is fabricated and evaluated for practical application, providing an energy density of 44.3 Wh kg−1 at a power density of 0.425 kW kg−1. This study indicates that the hollow LDH microsphere prepared by our method is a promising material for supercapacitors.