Hydrogen-enriched porous carbon nanosheets with high sodium storage capacity

A simple supercritical alcohol route was developed to fabricate hydrogen-enriched porous carbon nanosheets (H-PCNs). The as-prepared H-PCNs were tested as an anode active material for sodium ion batteries. Due to the unique hydrogen donation and alkoxylation ability associated with supercritical isopropanol, the hydrogen-to-carbon ratio of H-PCNs was as high as 2.3. The H-PCNs electrode exhibit an excellent reversible capacity of 300 mAh g−1 at 50 mA g−1 and remarkable cycling stability up to 2000 cycles at 1-5 A g−1. A high rate-performance of 74 mAh g−1 was also obtained at the high current density of 5 A g−1. The excellent electrochemical performance of H-PCNs for Na ion uptake is attributed to the high hydrogen-terminated groups and large amount of defects on the carbon sheets. In addition, the large interlayer spacing (0.38 nm), high specific surface area (147 m2 g−1) and high porosity (58%) would also contribute to the high Na ion uptake.