Trash to Energy: From Sugarcane Bagasse to High-Performance Anodes for Sodium-Ion Batteries

Sodium-ion batteries (NIBs) are considered as next-generation energy storage devices to substitute lithium-ion batteries in large-scale energy storage systems for smart grids and electric vehicles. Pursuing low-cost, resource-abundant, and high-performance anodes are decisive to the future growth and expansion of NIBs. Recently, several suitable cathode materials for NIBs have been successfully developed and investigated. However, the major hurdle is to obtain appropriate anode materials with reversible electrochemistry and fast kinetics for NIBs. Herein, we have successfully developed a new hard carbon (HC) anode derived from abundant sugarcane bagasse (SB) as the biomass precursor. We synthesized SB hard carbon (SB-HC) under various carbonization temperatures. SB has a unique balance of lignin, cellulose, and hemicellulose, which avoids full graphitization of the pyrolyzed carbon but guarantees an adequately ordered carbon structure for Na-ion transport. When compared to HC derived from waste apple biomass, which is rich in pectin and has less cellulose compared to SB, SB‐HC is less defective and has lower oxygen content. As a result, SB‐HC has a higher first‐cycle charge/discharge coulombic efficiency and enhanced cycling stability. In addition, SB‐HC has a distinctive flake‐like morphology, which can reduce Na+ diffusion length, resulting in outstanding high‐rate charge-discharge performance. The effects of pyrolysis temperature on electrochemical properties of both HC anodes are comprehensively studied.