Progress in the synthesis of carbon aerogels for advanced energy storage applications

Carbon aerogels, usually prepared from organic aerogel precursors, have many merits such as being light weight, high porosity, large surface area, excellent conductivity, and high temperature resistance for broad applications in the fields of adsorption, catalysis, and energy storage. Particularly, the application of carbon aerogels in advanced energy storage devices has gained increasing attention in recent years. This paper discusses the preparation and application of carbon aerogels derived from organic precursors. The development of resin- and biomass-derived carbon aerogels for application in supercapacitors and rechargeable batteries (e.g., Li-ion batteries – LIBs) is highlighted. Furthermore, the development and challenges of the carbon aerogel industry are discussed. This work offers a strategic guide to build a close connection between carbon aerogels and the energy storage economy. In general, the electrochemical performances mostly rely on the surface structures and chemical characteristics of carbon aerogels. Carbon aerogels possessing a 3D hierarchical porous network structure with appropriate microporosity and mesoporosity, heteroatom (e.g., N, S) doping, and active metal nanoparticle (e.g., MnO₂, Co₃O₄) loading are key indexes to determine the capacitance, rate capability, and cycling stability of the assembled supercapacitors. Resin-derived carbon aerogels have the advantages of large specific surface area and highly tunable pores for application in supercapacitors, but the poor mechanical properties hinder their application in flexible supercapacitors. In addition, carbon aerogels for application in rechargeable batteries are mostly used as the supports for electroactive substances in LIBs and the separators of Li–S and Na–S batteries. Carbon aerogels derived from biomass precursors, in comparison with conventional resin precursors, are promising alternatives owing to the benefits of low cost (abundant in nature), sustainability, eco-friendliness, large specific surface areas, tunable pore structures, and strong mechanical properties. The challenges of promoting biomass-derived carbon aerogels for practical use include simplifying the procedure and further reducing the time and cost required for the preparation of carbon aerogels from diverse biomass precursors.