Plasma-promoted surface regulation of a novel integrative carbon network for boosting the long-cycle capability of sodium-ion storage

In the process of Na + -storage in hard carbon materials, the sluggish (de)sodiation kinetics and irreversible reactions of surface groups with electrolytes are bottlenecks that limit the rate performance and long-term cycle stability. We successfully prepared a novel integrative carbon network material (ICN) on a large scale, and the carbon structure and surface oxygen groups were regulated to increase the rate and cycle capability using a plasma-assisted catalyst-free carbonization process. ICNs typically have ultrathin carbon nanofiber units (∼10 nm) interconnected by sp 2 hybrid covalent bonds, which form an interface-free integrative conductive network and ultra-short ion/electron transport pathways. The order degree of surface carbon stacking, interlayer spacing, and the content of –C O groups can be regulated by surface plasma treating to further boost kinetics and enhance reversible reactions. Thus, the ICN exhibits all-round improvements in terms of a large reversible capacity (389.5 mAh g −1 after 100 cycles at 50 mA g −1 ), a superior rate capability (285 mAh g −1 at 2000 mA g −1 after 3000 cycles), and good cycling stability (retain 72.2% after 10,000 cycles at 2000 mA g −1 ). According to the analysis of the dynamics, the capacitive mechanism by which Na + quickly inserts/adsorbs with the surface/subsurface atoms is primarily responsible for the excellent electrochemical performance. A full cell made up of an ICN anode and a Na 3 V 2 (PO 4 ) 3 cathode successfully lit the diode, demonstrating the ultra-high rate capability of ICN in practical application. It has a reversible capacity of 101.9 mAh g −1 at 1000 mA g −1 and maintains 76% after 2000 cycles, demonstrating the ultra-high rate capability of ICN in practical application. These results suggest a new perspective on the structure design of carbon-based materials for fast and long-life sodium-storage anodes.