Orbital hybridization states of carbon assisted robust inorganic-rich solid electrolyte interphase towards high initial coulombic efficiency hard carbon anode

Hard carbon is a vital anode material for sodium-ion batteries; however, the nonuniform growth of solid electrolyte interphase (SEI) film substantially diminishes its initial coulombic efficiency (ICE) and cycle life. The chemical and morphological properties of surface highly influence the electrode/electrolyte interfacial reactions. In this study, we have tuned orbital hybridization states forming an interface enriched with sp² hybridized carbon (sp²–C), which decreases the binding energy to solvent molecules and inhibits excessive solvent decomposition during SEI formation. Benefiting from successfully constructed inorganic-rich SEI, the ICE increased to 91 % and sodium storage capacity reached 346 mAh/g. Besides, the capacity retention rate was 90.7 % after 700 cycles at 1 A/g higher than pristine electrode (83.8 %).