Sustainable carbon electrode materials from biomass for redox flow batteries

Redox flow batteries (RFBs) are emerging as a promising technology for large-scale energy storage due to their flexibility, scalability, and long cycle life. These batteries play a crucial role in achieving optimal efficiency and performance for stationary energy storage applications. Carbon materials are integral to improving the performance of RFBs, particularly in electrodes and bipolar plates, due to their high conductivity, chemical stability, and large surface area. The shift towards sustainable alternatives has led to increased research interest in biomass-derived carbon materials as potential electrode components, offering a viable solution for developing fossil-free materials. This review provides a comprehensive overview of biomass-derived carbon materials and their applications in RFBs. The discussion includes the classification of biomass sources—plant-based, animal-derived, and microorganism-derived—as well as various synthesis techniques such as carbonization and activation (chemical, acid, alkali, salt, and physical activation). The relationship between biomass precursors and synthesis technologies is explored to highlight their impact on material properties. Additionally, the article delves into the properties of biomass-derived carbon materials and their role in RFB applications, including their use as electrode materials, conductive additives, and electrocatalysts. Specific carbon structures such as graphite, carbon nanotubes, graphene, and carbon felts are examined for their contributions to enhancing electrochemical performance. While graphite electrodes offer stability and conductivity, their low surface area and poor wettability limit performance. Carbon nanotubes and graphene, on the other hand, provide higher surface area and superior electrical conductivity, improving redox reaction efficiency. Furthermore, biomass-derived carbon materials have potential applications in separators and electrolytes, expanding their role in sustainable battery technologies. This article highlights recent advancements in designing biomass-derived carbon structures for RFBs, emphasizing their ability to enhance material efficiency, reduce costs, and improve the feasibility of RFBs for sustainable energy storage applications. By leveraging biomass as a carbon source, the development of environmentally friendly and cost-effective energy storage systems can be accelerated, paving the way for greener and more efficient battery technologies.