Structural and electrochemical modification of graphitic carbons by vapor-phase iodine-incorporation

Pristine and mechanically-milled graphitic carbons were chemically modified by vapor-phase iodine-incorporation. The effectiveness of iodine uptake during vapor iodation was gauged for pristine and mechanically-milled graphite. The doping of electronegative iodine, which is capable of triggering charge transfer reaction with carbon, was found to develop structural disordering, carbon–polyiodide covalent compounds (C–I3, C–I5), enhanced mesoporosity and reduced BET surface area in graphitic carbons. These intrinsic changes in iodine-modified graphite led to improved non-faradaic capacitance and development of faradaic pseudocapacitive reaction at ∼3.2 V versus Li. As a result, iodation develops manifold (∼100%) increment in gravimetric and volumetric capacity of precursor graphite, when tested versus Li. The effect of iodine-incorporation on physical and electrochemical properties of graphite is reported in detail.