Tailoring Ni─Co─MOF‐Derived Porous Nanostructures for Optimized Supercapacitor Electrode Performance

Supercapacitors have emerged as a vital component of energy storage systems because of their fast charge–discharge rate, high power density, and outstanding cyclic stability. This work examines the electrochemical performance of three nanostructured electrodes, S1 (S‐doped Ni─Co/C‐1:1), S2 (S‐doped Ni─Co/C‐1:2), and S3 (S‐doped Ni─Co/C‐2:1), synthesized by the coprecipitation route. Using the X‐ray diffraction (XRD) technique, well‐crystallized spinel phases are identified with average crystallite sizes of 13.4 nm (S1), 15.2 nm (S2), and 18.6 nm (S3). Scanning electron microscopy (SEM) displays that S3 presents a highly porous nanostructure with uniform morphology, whereas high‐resolution transmission electron microscopy (HRTEM) confirms lattice fringes with the interplanar spacing of 0.20 nm corresponding to the (111) plane. Brunauer–Emmett–Teller (BET) surface area analysis indicates the maximum value of specific surface area of 120.414 m 2 g −1 reported for S3. Electrochemical behavior by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) methods reveals excellent capacitive behavior whereby the S3 electrode can deliver a maximum specific capacitance of 1240 F/g at 1.0 A/g while retaining 87% capacitance after 8000 cycles. Electrochemical impedance spectroscopy (EIS) gives solution resistance and charge‐transfer resistance for the S3 as between 1.8 Ω and 3.2 Ω, respectively. The Dunn model indeed confirms pseudocapacitive dominance, with 90% at 100 mV s −1 capacitive contribution. Such results place S3 in the ranks of prospective electrode materials for advanced supercapacitors while suggesting an efficient platform to tune the metal ratio of metal–organic frameworks (MOFs) to maximize surface area and kinetics of charge transfer. Additionally, the pronounced pseudocapacitance exhibited by S3 is a good pointer on how to approach rational design of hybrid energy storage systems.