Present development and future perspectives on biowaste-derived hard carbon anodes for room temperature sodium-ion batteries

Sodium-ion batteries are regarded as an affordable alternative to commercial lithium-ion batteries in energy storage systems because of their abundant resources and comparable energy storage capabilities. Hard carbon is a prospective anode material to consider for the commercialization of sodium-ion batteries due to its promising electrochemical performance and the possibility of using renewable resources of bio-waste to obtain hard carbon. However, numerous disadvantages, including low initial coulombic efficiency and voltage hysteresis, continue to constrain the use of hard carbon in sodium-ion batteries. Various strategies have been attempted to address these challenges to transfer present promising research opportunities into practical applications. This review provides recent insights on bio-waste-derived hard carbons, which are classified into different types of hard carbon precursors, the effect of carbonization temperature and doping on the physical characteristics, and the variation in the property of hard carbon under different synthetic parameters is directly correlated with sodium storage process. We discuss the associated sodium storage mechanisms in-depth. This work also provides a future perspective on bio-waste-derived hard carbons and the feasibility of their practical utilization in room temperature type low-cost sodium-ion batteries.