Highly porous nanocomposites of Mn doped cobalt-based hydroxide/sulfide as high-performance electrode materials for hybrid supercapacitors

Abstract

Cobalt-based nanomaterials are a highly promising class of energy storage materials with high theoretical capacity and excellent long-term service life, such as metal doping and structural porousness of these cobalt-based nanocomposites, have been regarded as effective methods to further increase their active sites and improve their conductivity and performance. However, synthesizing cathode materials with high specific capacity and energy density through simplistic methods remains an immense obstacle. In this study, Mn doped cobalt-based hydroxide/sulfide nanocomposites with large pore volume as well as specific surface area were successfully synthesized. The Co(OH)2/CoS electrode doped with Mn has better charge storage capacity (capacity increase from 586.5C g−1 to 1030.8C g−1 at 0.5 A g−1), excellent rate performance (with a capacity retention of 75.8 % at 10 A g−1). Additionally, a hybrid supercapacitor (HSC) was constructed utilizing Mn-Co(OH)2/CoS and activated carbon (AC). HSC exhibited excellent charge storage capacity (166.3 F g−1 at 0.5 A g−1) and remained at 164.1 % of its original value after 30,000 cycles of testing with high current density. In addition, at a power density of 410.0 W kg−1, the assembled HSC device demonstrates a significant energy density of 62.1 Wh kg−1, revealing that porous Mn-Co(OH)2/CoS electrode materials showed excellent energy storage properties.