Emerging Trends in Nickel Sulfide Electrodes for High‐Performance Supercapacitors: Synthesis, Mechanisms, and Nanocomposite Innovations

Electrochemical supercapacitors (SCs) are increasingly recognized as pivotal in the field of energy storage, distinguished by their substantial specific capacitance, robust cyclic stability, and remarkable power density. These devices are not only environmentally friendly but also cost‐effective, which enhances their appeal in sustainable technological applications. One material that has gained significant interest lately is nickel sulfide (NiS). This compound is being explored for its potential in pseudocapacitors due to its unique chemical and physical traits that elevate electrochemical performance. This review focuses on the latest developments in SC electrodes based on NiS. It presents an in‐depth analysis of the energy storage mechanisms employed by NiS, along with a comprehensive examination of the different methods used for its synthesis. The versatility of NiS allows for various nanostructural morphologies, which are crucial in optimizing its functionality and efficiency. Additionally, the integration of NiS with other materials is discussed extensively. This includes combinations with carbon, oxides, and other sulfides, forming innovative nanocomposites. These composites are crucial for enhancing the electrochemical properties and performance of SCs. The review also explores how these material integrations influence the overall energy storage capacity and efficiency, presenting a forward‐looking perspective on the potential advancements in SC technology.