Sustainable bio-derived functional materials enabling efficient aqueous zinc-ion batteries: a mini review

The increasing need for safe, low-cost and sustainable electrochemical power storage has spurred the development of aqueous zinc-ion batteries (ZIBs) as a possible alternative to lithium-ion batteries. Among the variety of cathode materials explored, biomass-derived carbon compounds have attracted considerable attention due to their renewable origin, tunable porosity, abundant surface functional groups, and eco-friendly synthesis methods. However, the biomass source of these materials dictates their electrochemical performance, but more significantly their chemical structure, including pore architecture, defect density, graphitization degree, heteroatom functionalization, and interfacial chemistry. This mini review provides a critical summary of the correlation between the structural properties of biomass-derived carbon materials and their Zn²⁺ storage mechanisms and emphasizes the effects of structural engineering on ion adsorption, charge transfer, diffusion kinetics, pseudocapacitive behavior, and cycling stability. Recent progress in heteroatom doping, hierarchical porous designs and metal-organic framework (MOF)-derived carbon composites are presented with focus on their roles in boosting electrochemical performance. The review does not summarize individual findings but develops structure-property-performance correlations that give essential insights for rational design of high-performance biomass-based cathodes. Finally, the current challenges, such as scalable synthesis, mechanistic understanding with operando characterization, structural stability, and practical device integration, are critically discussed along with future perspectives for the development of sustainable and high-energy-density zinc-ion energy storage systems.