Advanced hybrid supercapacitors assembled with high-performance porous MnCo2O4.5 nanosheets as battery-type cathode materials

Porous MnCo2O4.5 nanosheets (NSs) were fabricated through a sequence of synthetic procedures containing initial solvothermal reactions, precursor aging in water, hydrothermal treatment, and final annealing conversion in air. These ultrathin NSs possessed a huge specific surface area of 104.93 m2 g−1 along with an average pore size of 14.15 nm. Electrochemical performance of the NSs was assessed in three-electrode & two-electrode systems. It was confirmed that the MnCo2O4.5 NSs delivered a specific capacity of 304.37 C g−1 at 1 A g−1 and 225.60 C g−1 at 10 A g−1 in 2 M of KOH electrolyte. To evaluate the practical application in electrochemical energy storage, a hybrid supercapacitor (HSC) was assembled with MnCo2O4.5 NSs as cathode and activated carbon (AC) as anode. The MnCo2O4.5 NSs//AC HSC exhibited a high energy density of 33.36 W h kg−1 at the power density of 950.83 W kg−1, and showed an outstanding cyclic durability with 100.04 % capacity retention over 5000 cycles at 6 A g−1. The current synthetic strategy provides a good pathway for the preparation of other transition metal oxides (TMOs)-based electrode materials with large surface area and superior electrochemical property for the further assembly of advanced HSC devices.