Developments in Sustainable Green Supercapacitors: A Minireview

This minireview revisits various biomass-derived carbon composites with metal oxides, layered double hydroxides, biopolymers, and the use of ionic liquids as electrolytes for green supercapacitors. These materials are abundant, stable, and nontoxic, offer high surface area, provide electrolyte accessibility due to their porous architecture, and have excellent electrical conductivity. Due to environmental concerns and the diminishing supply of fossil fuels, electrochemical energy storage devices have gained significant attention in recent years. Supercapacitors (SCs) hold a significant position due to their enhanced energy and power density compared to those of other energy storage devices. However, to utilize SCs effectively across various applications, their performance must be improved. Electronic devices are integral to daily life but can pose environmental hazards when discarded through conventional landfill or incineration methods. This is because these devices often contain harmful chemicals, such as sulfur, cyanide, and fluorine groups. To tackle this issue, there is increasing interest in developing green supercapacitor components, such as electrodes, electrolytes, binders, and conductive substrates, that are safe to dispose of and pose no environmental hazards. Since the electrode is crucial to a supercapacitor's performance, significant focus is devoted to developing electrode materials from clean and renewable sources, such as biomass-derived carbon and biopolymers. In fact, the use of such ecofriendly materials for electrodes and devices can advance other energy storage technologies as well.