Insights into the role of Mn doping in NiCo2S4 for enhanced electrochemical performance in supercapacitor applications

s The present study demonstrates a successful synthesis of manganese-doped nickel cobalt sulfides (Mn-NiCo 2 S 4 ), which deliver marked improvements in electrochemical properties compared to pristine NiCo 2 S 4 . Comprehensive structural, morphological, compositional, surface, and electronic characterizations provide clear insights into the enhanced performance. Specifically, we identify three primary factors contributing to the superior electrochemical behaviors of Mn-NiCo 2 S 4 : ( i ) the appearance of hollow nanorods, which facilitates electrolyte access and improves ionic transport; ( ii ) the synergistic effects arising from the Faradaic reactions, which play a crucial role in boosting the electrochemical performance of Mn-NiCo 2 S 4 compared to the unmodified NiCo 2 S 4 ; and ( iii ) the enhances electronic conductivity from increased electron density and effective charge redistribution due to Mn doping confirmed by density functional theory simulations and experimental observations, leading to reduced internal resistance and improved electrochemical kinetics. Remarkably, Mn-NiCo 2 S 4 achieves an exceptional specific capacity of 470   C   g -1 at a current density of 1   A   g -1 . Additionally, the Mn-NiCo 2 S 4 //AC asymmetric supercapacitor delivers impressive energy densities ranging from 37.09 to 84.85   Wh   kg -1 , corresponding to power densities decreasing from 7.09 to 0.79   kW   kg -1 ; maintaining 50.52% capacity retention after 10,000 cycles at 2   mA   cm -2 . These results underscore the potential of Mn-NiCo 2 S 4 and related doped materials as next-generation electrodes for advanced, high-performance supercapacitors, paving the way for significant advancements in energy storage technology.