Preparation of exfoliated graphite containing manganese oxides with high electrochemical capacitance by microwave irradiation

Exfoliated graphite (EG) containing manganese oxides was rapidly and efficiently prepared by microwave irradiation. The maximum expanded volume of EG was up to 317 mL g−1 when the mass ratio of natural graphite and nitric acid to potassium permanganate was 1:2:2. EG showed specific capacitance of 97.5 F g−1 at a scan rate of 1 mV s−1 due to a pseudo-capacitance originated from the deposited manganese oxide particles on the surfaces of EG. After 400 cycles, the specific capacitance of EG increased by 21.2% of initial capacitance demonstrating good cycling stability.