Biological pretreatment of bamboo biomass toward hierarchical carbon architectures for high-rate sodium storage

Abstract

Sodium-ion batteries (SIBs) demand sustainable anode materials to address the limitations of lithium resources. Bamboo, a fast-growing and structurally hierarchical biomass, holds promise as a precursor for hard carbon (HC) anodes, yet conventional carbonization struggles to optimize its rigid crystalline domains. Here, we propose a fungal-carbonization coupling strategy using white-rot fungi (Trametes versicolor) to biologically pretreat bamboo, achieving selective delignification and hemicellulose removal. This enzymatic process disrupts the hydrogen-bonded cellulose networks, reducing crystallinity and generating defect-rich amorphous matrices. During carbonization, the pretreated precursor evolves into a hierarchical architecture featuring curved graphene-like domains and closed nano-pores, synergistically enhancing ion diffusion and adsorption. The optimized HC anode exhibits a reversible capacity of 336 mAh g⁻¹ at 30 mA g⁻¹, an initial coulombic efficiency of 91.25%, and 66.7% capacity retention after 1000 cycles. Full-cell and flexible pouch-cell prototypes demonstrate remarkable cycling stability (approximately 80% and 77% retention after 200 cycles), outperforming most biomass-derived carbons. This work demonstrates a sustainable strategy for biological deconstruction-guided carbon engineering, offering new insights into designing advanced carbonaceous materials from biomass resources.