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

Abstract

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 (Cs) of 290 (± 5) F g−1 at a current rate of 0.5 A g−1, whereas cm-Mn3O4 obtained from the chemical conversion of cm-MnCO3 shows Cs 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 (τo = 140 ms), which allows it to deliver stored energy quickly at high power. Additionally, cp-Mn3O4 exhibits 71% capacitance retention after 15,000 cycles, 25 W h kg−1 energy density, and 202 W kg−1 power density at a current rate of 0.5 A g−1. Further, ex-situ XRD analysis demonstrates that cp-Mn3O4 retains its crystal structure to some extent even after prolonged cycles.