Solvothermal‐Derived Hierarchical NiFe ₂ O ₄ Hollow Microspheres as High‐Performing Anodic Material for Advanced Supercapacitor Applications

Hierarchical NiFe 2 O 4 hollow microspheres were designed via an easy and straightforward one‐pot solvothermal technique using the aid of controlled self‐assembly and Ostwald‐ripening‐driven hollow microstructure formation strategies. Comprehensive morphological characterizations confirmed the phase‐pure inverse spinel ferrite with high crystallinity displaying an appreciable surface area of 57.0 m 2 g −1 . The mesoporous hollow structure was endorsed by the self‐assembling of ethylene glycol stabilized ferrite nanoparticles that tailored the electronic band gap as verified from DFT studies and boosted the charge storage capability. The electroactive material exhibited notable specific capacitance of 437 and 560 F g −1 at voltage scan rate of 10 mV s −1 and current density of 5 A g −1 , respectively, in neutral electrolyte. The symmetric cell delivered specific energy of 15.46 Wh kg −1 @ specific power of 662.51 W kg −1 (0.2 A g −1 ) in the potential window of 1.1 V using neutral aqueous electrolyte. In contrast, the asymmetric AC//NiFe 2 O 4 coin cell configuration displayed specific energy of 76.5 Wh kg −1 @ specific power of 1080 W kg −1 (0.3 A g −1 ) in the potential window of 1.8 V. Thus, the versatile charge storing responses placed it as a promising candidate for next‐generation high‐performance electrochemical energy‐storage systems.