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 hard carbon microstructure for achieving a high plateau capacity still remains a significant challenge. Here, 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%, and an 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 the hard carbon. Combined in-situ Raman, in-situ XRD, and ex-situ XPS provide the insight into the sodium storage mechanism in hard carbon. This work offers an efficient strategy for constructing pseudo-graphite domains, contributing to a deep understanding of the sodium storage in hard carbon.