Revealing Effect of Aggregation Structure of Plant Precursors on Rate Performance of Carbon Anode for Sodium‐Ion Batteries

Abstract Plant‐based hard carbon is a highly promising anode material for sodium‐ion batteries. Numerous studies have dedicated significant effort to the selection of precursors; however, there has been limited comprehensive research on the low‐rate performance of plant‐based hard carbon. Indeed, the aggregated structure of cellulose and hemicellulose in precursors has been underestimated regarding its influence on the material properties. In this study, the inherent aggregated structure of kapok fiber is optimized. It has been observed that the aggregation structure of the precursor significantly influences the content of highly disordered carbon post‐carbonization, consequently impacting the rate performance of the derived anode material. To address the problems, aluminum ions innovatively are used to support the crushed cellulose‐hemicellulose arrays, and the prepared carbon anode has a capacity retention rate of up to≈70% at a current density increased from 0.05 to 3.2 A g⁻¹. This research not only clarifies the mechanism by which the structure leads to the decline of rate performance but also innovatively introduces the ion coupling method to repair the structure, thereby achieving the optimization of rate performance.