A Universal Biomass Conversion Method for High-Performance Hard Carbon Anodes

Abstract

Sodium-ion batteries (SIBs) are increasingly recognized as a viable alternative for large-scale energy storage compared to lithium-ion batteries (LIBs) due to their abundant natural availability, widespread distribution, and cost-effectiveness of sodium resources. However, SIBs encounter challenges such as low specific capacity, unsatisfactory rate performance, and short cycling life due to the large radius (1.07 Å) and sluggish transport rate of sodium ions. This scenario underscores the need to explore advanced anode materials possessing the capability for rapid, stable, and efficient insertion/extraction of sodium ions. Herein, we develop a universal reciprocal biomass processing method to prepare a series of high-performance hard carbon anodes derived from biomass. The utilization of biomass-based deep eutectic solvents (DES) leads to the disruption of intramolecular and intermolecular hydrogen bonds within cellulose in biomass feedstock, resulting in increased disorder and expanded interlayer spacings of hard carbon during the pyrolysis process. The optimal hard carbon anode derived from macadamia nut shells (MNSs) exhibits enhanced sodium-ion transport and storage capabilities treated by DES, featuring a high reversible capacity of 297.07 mAh g−1 at 20 mA g−1 and good rate performance. Other biomass resources such as bamboo, coconut, and pine highlight the versatility of the proposed reciprocal biomass processing method for synthesizing high-performance hard carbon anodes. This study presents a universal and green method to process biomass resources for synthesizing high-performance hard carbon anode materials.

Keywords: Hard Carbon, Anodes, Deep eutectic solvent, Biomass, Sodium-ion battery