Mesoporous manganese dioxide prepared under acidic conditions as high performance electrode material for hybrid supercapacitors

High surface area mesoporous manganese dioxide (MnO2) with α-phase crystalline structure has been synthesized by the reduction of potassium permanganate with ethylene glycol under acidic conditions. Nitrogen sorption analyses show that MnO2 synthesized under acidic conditions exhibits a type IV isotherm, indicating a mesoporous character. Electrochemical performances of MnO2 samples as supercapacitor electrode materials have been studied in a three-electrode system. A hybrid supercapacitor based on using a composite material (MnO2&Activated Carbon) as the positive electrode and activated carbon as the negative electrode has been fabricated. The hybrid supercapacitor fabricated using MnO2 synthesized under acidic conditions has excellent large current charge–discharge performance, and shows a practical cell voltage of 1.8 V and a capacitance of 22.1 F g−1 after 1500 cycles even in the presence of the dissolved oxygen. MnO2 synthesized in the absence of acid shows poor cycle performance and a low capacitance.

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► High surface area and mesoporous MnO2 has been synthesized under acidic conditions.
► Hybrid supercapacitors with MnO2&AC based positive electrodes have been fabricated.
► The practical cell capacitance is high up to 22.1 F g−1 with a lower IR.
► The cycle stability of mesoporous MnO2 based supercapacitors is obviously improved.