Covalent organic frameworks in supercapacitors: Unraveling the pros and cons for energy storage

Covalent organic frameworks are a type of crystalline porous materials that have recently been discovered. They are formed by covalent bonding and can have various molecular structures. Covalent organic frameworks can be synthesized using different methods and have gained significant attention in scientific research. They are now recognized as essential materials in technology due to their unique advantages. These advantages include their large surface area and porosity, high modifiability, presence of conjugated structures, availability of sufficient building blocks, low density, and high chemical stability. Covalent organic frameworks possess these properties because of the efficient linking of atoms in two and three dimensions, which allows for the construction of extended framework structures. Covalent bonds hold the molecules together and connect them to larger covalent structures. One particular area of interest is the development of energy storage devices. Covalent organic frameworks show promising capacitive response and the potential for high capacitance. Their capacitive behavior has attracted significant attention, especially regarding the various morphologies that can be achieved through different synthetic processes. However, the main challenge hindering the widespread use of covalent organic frameworks in electrochemical energy storage systems is their low specific capacitance and poor electrochemical performance, primarily due to their limited electrical conductivity. Efforts have been made to enhance the performance of covalent organic framework -based -materials by incorporating redox-active groups into the covalent organic framework skeleton, controlling morphology and hydrogen bonding, and creating hybrid systems with conducting polymers, carbon materials, chalcogenides, metal oxides, and other materials. Additionally, research has focused on developing advanced nanocomposites, such as binary, ternary, and quaternary systems, for cutting-edge energy storage applications. These endeavors aim to maximize the positive effects of covalent organic frameworks while minimizing their limitations. This review article provides a concise introduction to covalent organic frameworks, discusses the advantages and disadvantages of using covalent organic frameworks in supercapacitors, and gives a brief overview of the technology. It then delves into the latest advancements in covalent organic framework design and its composites. Furthermore, it examines the fundamental principles and strategies employed in this field to improve the performance of covalent organic frameworks-based materials in energy storage applications.