From biochar to battery electrodes: A pathway to green lithium and sodium-ion battery systems

Electrochemical energy storage devices that exhibit elevated power and energy density are essential for diminishing reliance on fossil fuels and serve a crucial function in the alternating storage of renewable energy. Among the myriad of energy storage technologies, carbon emerges as a superior electrode material due to its widespread availability, excellent electrical conductivity, and the ability to finely tune its intrinsic properties. In this context, biomass is a plentiful, cost-effective, and renewable resource for generating biochar that has garnered considerable research interest that is driven not only by its potential to address environmental challenges but also by its role in advancing sustainable energy storage technologies. Biochar is produced from biomass which can be tailored to optimize their structural and electrochemical attributes through various means, such as inducing porosity, expanding surface area, graphitization. This review explores the recent developments in the conversion and effective utilization of biomass, along with its derived biochar, as electrode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). It elaborates on diverse biomass sources and the pathway from technology development to commercialization while highlighting the potential of biochar to alleviate the pressure on essential raw materials. Additionally, it emphasizes the supplementary environmental sustainability benefits that these innovations confer.