One-pot synthesis of pure phase Mn3O4 at room temperature and probing its long-term supercapacitive performance

Present work deals with one-pot synthesis of pure phase mesoporous Mn3O4 nanoparticles by novel, easy, and cost-effective method at ambient conditions and probing its long-term supercapacitive performance. The co-precipitation-routed submicron MnCO3 particles (cp-MnCO3) and commercially available MnCO3 (cm-MnCO3) have been used as the precursor materials in the synthesis procedure. The nanoparticles of cp-Mn3O4 synthesized using cp-MnCO3 exhibits specific capacitance (C-s) of 290 (+/- 5) F g(-1) at a current rate of 0.5Ag(-1), whereas cm-Mn3O4 obtained from the chemical conversion of cm-MnCO3 shows C-s value of 204 (+/- 5) F g(-1) at identical current rate. The better electrochemical behavior of cp-Mn3O4 is ascribed to its hierarchical pore size distribution and lower diffusion resistance, which facilitates an easy electrolytic ionic diffusion in the sample. cp-Mn3O4 also exhibits smaller relaxation time constant ((o)=140ms), which allows it to deliver stored energy quickly at high power. Additionally, cp-Mn3O4 exhibits 71% capacitance retention after 15,000cycles, 25Whkg(-1) energy density, and 202Wkg(-1) power density at a current rate of 0.5Ag(-1). Further, ex-situ XRD analysis demonstrates that cp-Mn3O4 retains its crystal structure to some extent even after prolonged cycles.