Closed-Pore Regulation of Hard Carbon Based on Rapid Diffusion Dynamics to Enhance Sodium Storage

Hard carbon, as a preferred anode material for sodium-ion batteries (SIBs), faces significant challenges in constructing a closed-pore structure and a rapid diffusion pathway under low-temperature carbonization. This severely hinders the reversible storage of sodium in hard carbon at high rates. This work proposes a thermal-mechanical coupling strategy to prepare biomass-derived carbon with abundant closed-pore structures and rapid diffusion kinetics for high-performance sodium storage. Under the dual influence of thermal and force fields, graphitic microcrystalline layers undergo reconstruction through slip and rearrangement processes. This transforms disordered amorphous carbon into an ordered carbon layer, forming effectively curved closed-pore walls that create abundant closed-pore structures within the carbon matrix. The PPHC-10 delivers a high reversible capacity of 333.01 mAh g –1 at 25 mA g –1, with a remarkable initial Coulombic efficiency of 84.6% and outstanding rate performance. Through in situ and ex situ characterizations, the sodium storage mechanism of PPHC-10 is elucidated as follows: an adsorption-insertion-pore filling. This study introduces a strategy for designing high-performance SIB anode materials with significant potential for industrial-scale production.