Cellulase-Mediated Modulation of Crystalline Cellulose Content and Pore Structure in a Biomass Precursor for High-Performance Sodium Storage in Hard Carbon Anodes

The composition and distribution of cellulose, hemicellulose, and lignin in biomass determine its crystallinity and pore structure, which in turn influence the electrochemical properties of the derived hard carbon. This study employed cellulase pretreatment to modify the composition and structure of bamboo precursors, facilitating the development of high-performance bamboo-based hard carbon anodes. During pretreatment, cellulase selectively removed cellulose from the amorphous regions of bamboo while preserving the crystalline cellulose, improving the crystallinity. The enzymatic action also created a porous structure on the bamboo surface. Following carbonization, the resulting hard carbon exhibited more ordered carbon layers, larger carbon microcrystals, and a richer microporous structure. Electrochemical testing revealed that the sodium storage capacity of cellulase-pretreated bamboo-based hard carbon (HC-BE-12 h) significantly increased from 280 mAh g^-1 to 345 mAh g^-1 at 20 mA g^-1, compared to untreated bamboo-based hard carbon (HC-RM). Additionally, the rate performance improved, with the capacity increasing from 232 mAh g^-1 to 276 mAh g^-1 at 1 A g^-1, and cycling stability was enhanced, achieving 94% capacity retention after 100 cycles at 1 A g^-1.