Lignocellulolytic Bacterial Engineering for Tailoring the Microstructure of Hard Carbon as a Sodium-Ion Battery Anode with Fast Plateau Kinetics

Abstract

Lignocellulosic biomass-derived pyrolysis hard carbon (LCB-HC) shows promising commercial potential as an anode material for sodium-ion batteries (SIBs). LCB compromises multiple biopolymer carbon sources, including cellulose, hemicellulose, and lignin, which influence the formation and microstructure of pyrolysis HC. However, the poor plateau kinetics of LCB-HC is one of the main obstacles that severely limits its energy density with high power density, which could be attributed to the narrow interlayer distance and the lack of abundant closed pores for the intercalation/filling of Na⁺. Herein, we proposed a bottom-up approach to tailoring the microstructure of LCB-HC by regulating the components of the LCB precursor at the molecular level using bioenzymes secreted by lignocellulolytic bacteria. This mild and efficient enzymatic hydrolysis pathway partially depolymerized the biopolymers of basswood specifically, thereby enabling the construction of a small curved-graphite domain architecture with increased closed pores and an enlarged interlayer distance of LCB-HC, benefiting the low-voltage plateau Na⁺ storage with accelerated kinetics. As a result, the basswood-derived HC delivers a reversible capacity of 366.4 mAh g^-1 and performed remarkable plateau capacity retainability with a high proportion of 74.3% even with increased current density to 1000 mA g^-1. Such a microbial-chemistry-assisted approach provided insights into tailoring the microstructure of LCB-HC to construct high-performance SIB anode materials.