Ni/Mn electroactive nanohybrids physic-chemical properties for ulterior new generation of supercapacitors

Abstract

In this paper, highly mesoporous hierarchical mono- and bi- Ni and/or Mn based hydroxide and/or carbonate nanohybrids were synthesized using a facile free template hydrothermal method and investigated as high-performance electroactive nanomaterials for ulterior new generation of supercapacitors. Controlling the Ni/Mn precursors molar ratio and the growth conditions can offer preponderances for performances enhancing via a comparative products physic-chemical properties which were carried out using different techniques like: XRD, FTIR, Raman, XPS, HRTEM/FESEM, EDS, UV–visible and BET. The structural results confirmed the formation of MnCO3, α-3Ni(OH)2·2H2O and Ni(HCO3)2 phases in the synthesized nanomaterials, with different morphologies (nanofibers, nanocubes, porous micro/nanoflowers) depending on the hydrothermal synthesis conditions. Meanwhile, the influence of Ni and Mn transition metal species co-existence on the resulting composition and their optical properties were also discussed. Moreover, their electrochemical measurements were also performed in a 6 M KOH aqueous electrolyte using three electrode system. The results show that 2Ni(HCO3)2/MnCO3 nanohybrid exhibited the highest specific capacitance (capacity) of 2777 F g−1 at 5 mV s−1 (320 mAh.g−1 at 1 A g−1) with high rate capability. This excellent electrochemical kinetics performance is ascribed to the optimized composition of Ni/Mn and its unique nanostructured configuration with intercalated ions, indicating a great potential of this new kind of nanohybrids to deliver both high energy density and high power density in future energy storage devices.