Effects of sulfuric acid treatment on the microstructure and electrochemical performance of a polyacrylonitrile (PAN)-based carbon anode Original Research Article

To examine whether acid treatment of a non-graphitizing hard carbon influences positively or negatively its electrochemical anodic performance, this study reports the effects of sulfuric acid treatment on the microstructural changes and electrochemical performance of PAN-based hard carbons prepared at various temperatures. It was found that PAN-based hard carbons heat treated at 900 °C (TAN9) exhibit an increased reversible capacity by up to ∼20% and a decreased irreversible capacity by up to ∼8% following the sulfuric acid treatment (TAN9S series). Since small changes in microstructure, except for slight reductions in surface area and crystallite size (La) value, were observed after sulfuric acid treatment, it was speculated that the capacity responses of samples in series TAN9S were due to the introduction of new functional groups such as single bondSO3H and single bondSO4H. As the newly introduced functional groups are st