One Stone, Three Birds: Innovations and Challenges of Layered Double Hydroxides in Batteries, Supercapacitors, and Hydrogen Production

Layered double hydroxides (LDHs), notable for their unique two-dimensional layered structures, have attracted significant research attention due to their exceptional versatility and promising performance in energy storage and conversion applications. This comprehensive review systematically addresses the fundamentals and diverse synthesis strategies for LDHs, including co-precipitation, hydrothermal synthesis, electrochemical deposition, sol-gel processes, ultrasonication, and exfoliation techniques. The synthesis methods profoundly influence the physicochemical properties, morphology, and electrochemical performance of LDHs, necessitating a detailed understanding to optimize their applications. In this paper, the role of LDHs in batteries, supercapacitors, and hydrogen production is critically evaluated. We discuss their incorporation in various battery systems, such as lithium-ion, lithium–sulfur, sodium-ion, chloride-ion, zinc-ion, and zinc–air batteries, highlighting their structural and electrochemical advantages. Additionally, the superior pseudocapacitive behavior and high energy densities offered by LDHs in supercapacitors are elucidated. The effectiveness of LDHs in hydrogen production, particularly through electrocatalytic water splitting, underscores their significance in renewable energy systems. This review paper uniquely integrates these three pivotal energy technologies, outlining current innovations and challenges, thus fulfilling a critical need for the scientific community by providing consolidated insights and guiding future research directions.