Acidic Potassium Permanganate-Induced Hierarchical Pores in Bamboo-Based Hard Carbon for High-Performance Sodium-Ion Batteries

Due to its unique structure and high capacity, bamboo-based hard carbon is often regarded as the most promising anode material for sodium-ion batteries. However, low sodium storage ability and poor Na⁺ transportation limit the development of bamboo-derived hard carbon. In this study, bamboo powder (BP) was pretreated with acidic potassium permanganate, in which the strong oxidizing properties introduced more oxygen-containing functional groups into the carbon skeleton. In addition, the two-step carbonization process facilitated the formation of hierarchical pore structures in the bamboo-based hard carbon (BP-A-P). Electrochemical measurements demonstrated that BP-A-P exhibited superior activity and stability. Under the current multiplication of 0.1 C, a reversible specific capacity of 338 mAh/g was achieved with a high first Coulombic efficiency of 81.7%. The excellent performance in sodium transportation and storage is mainly attributed to the rich micropores and abundant closed pores, which are induced by acidic potassium permanganate. Moreover, BP-A-P exhibits superior stability with a specific capacity maintained at 273 mAh/g after 100 cycles. Thus, acidic potassium permanganate treatment provides a new strategy for achieving complex hierarchical pores in bamboo-based hard carbon for high-performance sodium-ion batteries.