Coal-Based modified Carbon for High Performance Sodium-Ion Battery

The porous carbon has been synthesized with anthracite as the carbon precursor, NaCl as the template, NaOH as the activator, followed by high-temperature annealing. The coal-based graphene is successfully synthesized by the modified Hummers method. The structure and morphology characterizations of the as-synthesized coal-based carbon are performed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectra, and Nitrogen adsorption/desorption isotherms. The coal-based porous carbon shows outstanding electrochemical performance as anode for sodium-ion battery without adding any conductive agent due to its porous structure, and after 1000 cycles at the current density of 500 mA/g, it can provide the specific capacity of 150.4 mA h/g with 92.4% capacity retention based on the capacity of the tenth cycle, and also demonstrate good rate capability. The coal-based graphene also displays excellent long-life cycling performance, with 175.3 mA h/g specific capacity after 100 cycles at a high current density of 500 mA/g, after 1000 cycles, keeping almost no fading, which is attributed to its small dynamic impedance of sodium ion intercalation/de-intercalation. Thereby, the coal-based porous carbon/graphene could be considered as one of the most promising anodes of sodium-ion batteries.