Electrochemical Behavior of the Biomass Hard Carbon Derived from Waste Corncob as a Sodium-Ion Battery Anode

Biomass-derived hard carbon exhibits remarkable potential as an anode material for sodium-ion batteries (SIBs) owing to its inexpensive cost, availability of resources, and excellent electrochemical performance. However, the relatively low initial Coulombic efficiency (ICE) significantly confines the realistic application of hard carbon anode materials in SIBs. In this work, corncob-derived hard carbon (CDHC) materials were synthesized from biomass waste corncob. It has been found that the interlayer spacing of the synthesized hard carbon material is greater than 0.37 nm, which clearly surpasses the layer spacing of graphite. This larger layer spacing is favorable for the intercalation and deintercalation ability of sodium ions during the charging and discharging processes. When CDHC is applied by the anode of sodium-ion batteries, it shows excellent sodium storage performance, with a maximum reversible capacity of approximately 311 mAh g^–1 and the first Coulombic efficiency close to 80%.