Codoped Holey Graphene Aerogel by Selective Etching for High‐Performance Sodium‐Ion Storage

Abstract The pursuit of more efficient carbon‐based anodes for sodium‐ion batteries (SIBs) prepared from facile and economical methods is a very important endeavor. Based on the crystallinity difference within carbon materials, herein, a low‐temperature selective burning method is developed for preparing oxygen and nitrogen codoped holey graphene aerogel as additive‐free anode for SIBs. By selective burning of a mixture of graphene and low‐crystallinity carbon at 450 °C in air, an elastic porous graphene monolith with abundant holes on graphene sheets and optimized crystallinity is obtained. These structural characteristics lead to an additive‐free electrode with fast charge (ions and electrons) transfer and more abundant Na + storage active sites. Moreover, the heteroatom oxygen/nitrogen doping favors large interlayer distance for rapid Na + insertion/extraction and provides more active sites for high capacitive contribution. The optimized sample exhibits superior sodium‐ion storage capability, i.e., high specific capacity (446 mAh g −1 at 0.1 A g −1 ), ultrahigh rate capability (189 mAh g −1 at 10 A g −1 ), and long cycle life (81.0% capacity retention after 2000 cycles at 5 A g −1 ). This facile and economic strategy might be extended to fabricating other superior carbon‐based energy storage materials.