Hydrangea-like mesoporous carbon architectures embedded with MnO_x nanoparticles for solid-state asymmetric supercapacitors with enhanced areal capacitance

Hydrangea-like mesoporous carbon architectures embedded with MnO_x nanoparticles (MnO_x@C) are synthesized via the pyrolysis of Mn-MOFs (Mn-based metal organic frameworks) grwon on nickel foam as a binder-free electrode for asymmetric supercapacitors. The as-prepared MnO_x@C featuring stacked carbon flakes with mesoporous structure and embedded with nanosized MnO_x particles exhibit superior electrochemical performances with a specific areal capacitance of 1518 mF cm^-2 at a current density of 3 mA cm^-2. An asymmetric supercapacitor that is fabricated using MnO_x@C as cathode and activated carbon as anode demonstrates remarkable areal power density of 12.2 W cm^-2, areal energy density of 169.4 mWh cm^-2 and excellent rate capability. This work provides a facile and effective strategy to construct MnO_x@C supercapacitive materials so as to efficiently enhance electron transport at the meantime achieve rapid ion diffusion.