Spinel NiCo ₂ O ₄ ‐Based Materials for High‐Performance Supercapacitors: Experimental and Theoretical Insights

Supercapacitors (SCs) have gained huge attention due to high power density, long life cycles, and fast charge–discharge capability, which can fulfill the rising demand for efficient and sustainable energy storage technologies. Spinel NiCo 2 O 4 has been considered as the leading candidate for supercapacitors because of excellent redox behavior, abundance, environmental friendliness, and high theoretical capacitance. On the other hand, shortcomings, such as poor electrical conductivity, less surface area, and structural instability, limit their practical applications. The present review demonstrates the recent development in synthetic protocols, structural modification, and hybrid formation with other materials to enhance the electrochemical performance of NiCo 2 O 4 ‐based electrode materials. The various‐shaped nanostructured spinel NiCo 2 O 4 has been integrated with carbonaceous, Oxide/hydroxide, polymers, transition metal disulfides, and other materials, showing remarkable improvement in specific capacitance, rate capability, and cyclic stability. In addition, density functional theory (DFT) studies are highlighted to elucidate atomistic‐level insights into electronic structure, ion diffusion, and electrode–electrolyte interactions, providing a mechanistic understanding of performance enhancement. By correlating theoretical predictions with experimental observations, this review identifies key structure–property–performance relationships governing NiCo 2 O 4 ‐based supercapacitors. Finally, existing challenges and future research directions are outlined to guide the rational design of high‐performance, durable, and scalable NiCo 2 O 4 ‐based electrode materials for advanced energy storage applications.