Revolutionary NiCo layered double hydroxide electrodes: Advances, challenges, and future prospects for high-performance supercapacitors

The increasing global energy demand and transition to renewable sources emphasize the critical need for advanced energy storage technologies. Supercapacitors, with their high power density, rapid charge/discharge rates, and long cycle life, have emerged as a promising solution. Among various electrode materials, NiCo layered double hydroxides (NiCoLDHs) are particularly notable due to their tunable composition, large surface area, high electrical conductivity, multiple redox states, and exceptional redox activity. This review comprehensively explores the structural and electrochemical properties of NiCoLDHs, highlighting recent advancements in their development as revolutionary electrode materials for supercapacitors. Strategies for enhancing capacitance, such as doping with metals/non-metals, hybridization with carbon materials (e.g., graphene, carbon nanotubes, biomass-derived carbon), and integration with metal oxides, sulfides, selenides, MXenes, MOFs, and conducting polymers, are systematically discussed. Additionally, synthetic methodologies and their impact on electrochemical performance are explored. Current challenges, including scalable synthesis, structural stability, and enhanced energy and power densities, are addressed. Insights from computational modeling and density functional theory provide guidance for optimizing performance at commercial scales. This work provides an overview of advances in NiCoLDHs for next-generation, cost-effective, and sustainable energy storage devices.