MnCO3: a novel electrode material for supercapacitors

In this manuscript, MnCO3 is introduced as a novel electrode material for supercapacitors. MnCO3 was synthesized by a hydrothermal method using KMnO4 and commercial sugar as precursors. The synthesized product was characterized by powder X-ray diffraction, SEM, TEM and Raman spectroscopic studies. Rietveld refinement of powder X-ray diffraction confirmed the formation of a pure phase of MnCO3. Microscopic studies revealed particles of different shapes with sizes varying from 0.1 to 0.3 mm. Elemental mapping demonstrated a uniform distribution of manganese, carbon, and oxygen and there are no other impurity elements observed. The capacitive storage performance of MnCO3 was evaluated in three different electrolytes, namely, 0.1 M Na2SO4, 0.1 M Mg(ClO4)(2) and 6 M KOH by cyclic voltammetry and galvanostatic charge-discharge cycling. A high specific capacitance of 216 F g(-1) was obtained at a high loading level of 1.5 mg cm(-2) for submicron sized particles of MnCO3 in a 0.1 M Mg(ClO4)(2) electrolyte. Good reversibility, high coulombic efficiency, respectable rate performance and long cycle-life are also reported for MnCO3. This study opens up ample avenues to explore a new class of carbonate based materials for supercapacitor applications.