Hydrothermal Self-assembly of Manganese Dioxide/Manganese Carbonate/Reduced Graphene Oxide Aerogel for Asymmetric Supercapacitors

• Three-dimensional aerogels of MnO2/MnCO3/graphene were synthesized.
• The nanostructures of MnCO3 nanoparticles and MnO2 nanorods were investigated.
• The energy density reaches 17.8 W h kg−1 at 400 W kg−1.

A facile strategy has been used to prepare MnO2/MnCO3/rGO aerogels (MGA) with good electrical conductivity and high mechanical strength. Shape-controlled rod-like MnO2 and particle-shaped MnCO3 hybrid nanostructures is incorporated with reduced graphene oxide (rGO). The 3D aerogels were tailored and directly used as the electrode of supercapacitor without adding polymer binder or conductive additives. Asymmetric supercapacitors were fabricated using MGA as the positive electrode and rGO aerogel (GA) as the negative electrode in a neutral aqueous Na2SO4 electrolyte. The asymmetric supercapacitor exhibits an energy density of 17.8 W h kg−1 with a power density of 400 W kg−1 in a stable potential window of 0–1.6 V. In this study, we first provide a new pathway to fabricate MnO2/MnCO3/rGO ternary composite for aerogel-based asymmetric supercapacitors.