Sustainable Carbon Materials from Sucrose as Anodes for Sodium-Ion Batteries

The implementation of sodium-ion batteries for renewable energy storage requires the development of sustainable electrode materials. Usually, these materials are produced through complex energy-intensive processes that are challenging to scale and involve expensive and/or toxic reagents. In this study, sustainable hard carbon materials, some doped with iron, synthesized from sucrose using a simple, fast, and cost-effective two-step eco-friendly process, are investigated as anodes for sodium-ion batteries. The influence of physicochemical and structural material properties on electrode reversible capacity, cycling stability, and efficiency is analyzed. The SC900 material, which exhibits a certain development of graphite-like structure, though not strictly graphitic, showed the best electrochemical performance, providing discharge capacities exceeding 100 mAh g^-1 after 400 cycles with excellent cycling stability and high coulombic efficiency. The capacity of the materials increases as d₀₀₂ decreases, (i.e., as the degree of structural order increases), to the optimum value of ~0.3700 nm. However, a further decrease in d₀₀₂ to values characteristic of quasi-graphitic materials, as a consequence of the catalytic effect of iron, hinders Na⁺-ion storage, which, in addition to the low electrochemical activity of the iron oxides present, leads to much lower capacities.