Advances in graphene-based electrodes for high-performance supercapacitors

Supercapacitors (SCs) are crucial energy storage devices because of their high power density, long cycle life, and excellent charge/discharge performance. However, their lower energy density compared to batteries has driven extensive research into advanced materials and composite designs. This paper discusses recent progress in SC technology, focusing on electrode and electrolyte development. Hybrid electrodes enhance both electric double-layer capacitors (EDLCs) and pseudocapacitors, optimizing energy and power density. Graphene-based materials, including ternary and quaternary composites, are promising due to their high specific capacitance, conductivity, and longevity. Innovations like 3D graphene foam, graphene aerogels, and graphene-doped metal oxides address restacking issues, thereby improving cycle life. Electrolytes are critical for SC performance. Aqueous electrolytes are cost-effective and safe but have a narrow voltage window, limiting energy density. Organic and ionic liquid electrolytes offer higher energy density but suffer from relatively high costs and issues related to their high viscosity. Hybrid electrolytes combine the benefits of both, enhancing compatibility with advanced electrode architectures. This review highlights the synergistic evolution of electrodes and electrolytes, paving the way for a new generation of high-performance supercapacitors with improved energy storage capabilities.