Sustainable development of artificial graphite anode material for Li-ion batteries from almond nutshells biochar

The growing demand for graphite as anode material in lithium-ion batteries (LIBs) has intensified the search for sustainable alternatives to conventional fossil-derived sources, motivating the exploration of abundant biomass-based precursors and catalytic strategies for low-temperature graphitization. Almond nutshell biochar was converted into graphitic carbon via catalytic treatment, studying the influence of the transition metal catalyst (Fe, Ni and Co) on the graphitization degree and electrochemical performance. Metallic Fe was found to be the most effective catalyst, and the graphitization temperature, iron-based catalyst nature and catalyst to biomass ratio were systematically studied and compared to those of commercial graphite and synthetised petroleum coke graphite. Iron catalysed graphite exhibits highly ordered graphitic carbon structure at 1300°C with a graphitization degree of 0.962 and a low I D /I G ratio of 0.06. The optimized material delivered a discharge capacity of 332 mAh g⁻¹, comparable to petroleum coke–derived graphite treated at 2800°C and approaching commercial artificial graphite (343 mAh g⁻¹). Catalyst nature and loading strongly affected structural ordering and electrochemical behaviour, with metallic Fe promoting higher crystallinity, while Fe₂O₃-derived samples exhibited improved rate capability due to a higher defect density. This work demonstrates that the catalytic graphitization of almond nutshell biochar can be used to produce battery-grade graphite at significantly lower temperatures. This highlights the potential of using agricultural biomass as a sustainable source of materials for LIB anodes.