Facile preparation of MnO₂@C composite nanorods for high-performance supercapacitors

Novel MnO₂@C composite nanorods were successfully prepared by a facile solvothermal method. The results showed that a uniform carbon layer was formed around the MnO₂ nanorods. The carbon layer provided a highly conductive pathway to boost the charge transport involved during the capacitance generation. The electrochemical properties of MnO₂@C composite nanorods were investigated by cyclic voltammetry and galvanostatic charge–discharge. The composites as electrode materials of supercapacitors exhibited high specific capacitance (295 F/g) compared with MnO₂ nanorods (149 F/g) with a wide operation window (0–1.0 V). The electrochemical impedance spectroscopic studies showed the charge-transfer resistance (R_ct) of the MnO₂@C composite nanorods (1.10 Ω) was much lower than that of pure MnO₂ (2.53 Ω). Moreover, the MnO₂@C composite nanorods exhibited excellent cycling behavior with no more than 5 % capacitance loss after 2000 cycles. These results indicated that the MnO₂@C composite nanorods could be a promising electrode material for high-performance electrochemical capacitors.