In situ preparation of pseudo-graphite domains in hard carbon via molecular engineering towards high-performance Na-ion batteries

Abstract

Hard carbon has gained significant attention as a potential anode material for sodium-ion batteries owing to its affordability and high specific capacity. Nevertheless, the efficient regulation of the hard carbon microstructure for achieving a high plateau capacity still remains a significant challenge. Herein, hard carbon materials enriched with pseudo-graphite domains are prepared by controlling esterification to in situ introduce benzene ring structures into glucose. The optimized hard carbon (GI25) exhibits a remarkable specific capacity of 312.6 mAh g⁻¹, achieving an impressive initial coulombic efficiency (ICE) of 91.9%, as well as excellent cycling stability (capacity retention of 97.7% at 100 mA g⁻¹ after 100 cycles) and rate performance (177.4 mAh g⁻¹ at 1000 mA g⁻¹). Experimental results and density functional theory (DFT) calculations unlock the diffusion dynamics of sodium ions in hard carbon. Combined in situ Raman, in situ XRD, and ex situ XPS provide insight into the sodium storage mechanism in hard carbon. This work offers an efficient strategy for constructing pseudo-graphite domains, contributing to a deeper understanding of sodium storage in hard carbon.