Mn and S-doped nickel molybdate/nickel molybdate hydrate micro-structures for supercapacitor applications

Abstract

The scientific community is still attempting to understand the synergistic interaction between heteroatom doping and the design of rational heterostructured metal oxides. This is a significant and efficient method for constructing high-capacity electrochemical energy storage systems. In the present work, manganese (Mn) and sulfur (S) are co-doped precisely into nickel molybdate and nickel molybdate-hydrate on 3D nickel-foam (Mn-S-NiMoO4 and/ NiMoO4 center dot xH2O@NiF denoted as Mn-S-NMO) using a novel chemical approach for ameliorating the charge storage kinetics. The Mn-S-NMO electrode has demonstrated incredible specific capacitance of 10758.75 F g-1 at 6 A g-1 compared to the undoped NMO (2280 F g-1 at 6 A g-1) electrode, which is one of the highest reported values for metal oxides to date. The as-availed remarkable specific capacitance of Mn-S-NMO is attributed to its unique crystal structure, the collaboration of dual-ion dopants, interfacial synergistic modifications, the presence of multi-valent ions, defined oxygen vacancies, improved conductivity, increased active sites, rapid ion diffusion and electron transfer, charge-transfer efficiency, and reliable cycling stability. Moreover, a symmetric supercapacitor consisting Mn-S-NMO//Mn-S-NMO configuration achieves an energy/power density of 52.4 Wh kg-1//2100 W kg-1 and also demonstrates durable redox cycle life with 88.7% specific capacitance retention even after 20000 redox cycles at an excessive current density of 15 Ag-1. The resultant symmetric supercapacitor, developed by combining two devices in series, has successfully powered a "CNED" colorful panel made up of 42 LEDs at full brightness for 10 min, demonstrating (through synergistic modulation) the practical significance and scientific merits of the heteroatom-doped Mn-S-NMO electrode for real-world commercial appliances.