Oxygen functionalization boosted sodium adsorption-intercalation in coal based needle coke

In this work, oxygen functional groups (OFGs) was introduced into needle coke to increase sodium storage sites (CO) and tailor the interlayer distances from 3.44 to 3.84 Å for Na+ adsorption and intercalation. The OFGs are determined precisely using X-ray absorption near-edge structure spectroscopy and thermogravimetric-mass spectrometry. Benefiting from the coordination of fast surface redox reaction kinetics and boosted Na+ intercalation process, the resulting material under optimal oxidization realizes a superior reversible capacity of 385 mA h g−1 at 0.05 A g−1, showing great potentials in the large-scale application for sodium ion batteries anodes.