Mn and S-doped nickel molybdate/nickel molybdate hydrate micro-structures for supercapacitor applications
Ahmed H. Al-Naggar, Vijaykumar V. Jadhav, Shoyebmohamad F. Shaikh, Balaji G. Ghule, Rajaram S. Mane
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-NiMoO 4 and/ NiMoO 4 ⋅xH 2 O@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.