Recent Progress in the Synthesis of Layered Double Hydroxides and Their Surface Modification for Supercapacitor Application

The need for energy storage and the rapid development of new electronic platforms have prompted intense research into small and secure energy storage devices, particularly supercapacitors (SCs). Layered double hydroxides (LDHs) are potential electrode materials for SCs because of their excellent physicochemical and electrical characteristics. They involve interlayer spacing, high oxidation states, simplicity of synthesis, and distinct morphologies. Despite their potential, several kinds of LDHs still face constraints, such as particle aggregation, moderate surface area, and high resistance, which limit their use in energy storage. To overcome these challenges and enhance the electrochemical performance of LDHs, they have used strategies such as anion intercalation, oxygen vacancy, heteroatom, surfactant, fluorine, and metal doping, which have been demonstrated as electrode materials for SCs. Therefore, this review discusses recent advances in different LDHs and studies comparing bare and modified LDH for three- and two-electrode systems, with an emphasis on their morphologies, surface areas, and electrical properties for SC applications. It was found that modified LDHs achieve enhanced electrochemical performance in comparison to their corresponding bare LDHs. Consequently, there are potential opportunities to modify the surface of the recently invented LDHs for electrochemical investigations, which could result in improving their performance. This review also presents future perspectives on LDH-based energy storage devices for supercapacitors.