Covalent Organic Frameworks-Based Hybrid Materials for Electrochemical Energy Storage: Advances in Supercapacitors and Batteries.

The growing global energy demand and the need for sustainable energy technologies have accelerated the development of advanced electrochemical energy storage systems. Covalent organic frameworks, class of crystalline porous polymers formed through reversible covalent bonding, have emerged as promising materials for energy storage applications. Their tunable porosity, high surface area, structural diversity, and high chemical stability make them attractive electrode materials for supercapacitors and rechargeable batteries. This review highlights recent advances in COF-based composites and their enhanced electrochemical performance in different energy storage devices. Particular emphasis is given to rational design strategies in which COFs are combined with conductive polymers, carbon-based nanomaterials, and metal oxides. These hybrid structures help overcome the inherent limitations of pristine COFs, such as low electrical conductivity and limited redox activity. The relationship between structure, properties, and electrochemical performance of COF-based electrodes is critically discussed for batteries and supercapacitors. Key performance parameters, including specific capacity, rate capability, and cycling stability, are systematically analyzed. Despite significant progress, several challenges remain, with scalable synthesis methods, cost-effectiveness, and long-term stability. Upcoming research should focus on the development of multifunctional COF composites, environmentally friendly synthesis approaches, and the application of machine learning techniques to accelerate the optimization of high-performance energy storage materials.