Perspectives on critical properties of fullerene derivatives for rechargeable battery applications

C_n fullerene materials, composed exclusively of carbon atoms arranged in closed cages featuring pentagonal and hexagonal patterns, have garnered significant interest for their application in rechargeable batteries due to their distinctive and fascinating properties. Nonetheless, pristine C_n fullerenes exhibit several limitations that hinder their full potential, such as low specific capacities, suboptimal physicochemical properties, limited electronic conductivity, and uncertain redox potentials. Consequently, C_n fullerene derivatives, which incorporate additional functional groups, have emerged as promising candidates to address these shortcomings in rechargeable battery systems, as their properties can be chemically fine-tuned for optimal performance. From this perspective, a brief yet profound overview of fullerene derivatives and their application in batteries is presented according to their roles, specifically as 1) electrode active materials, 2) electrolyte additives, and 3) others. Particularly, the critical properties necessary for rechargeable batteries are summarized, suggesting that they have a high potential for more advanced battery systems.