Edge Graphitized Oxygen‐Rich Carbon Based on Stainless Steel‐Assisted High‐energy Ball Milling for High‐Capacity and Ultrafast Sodium Storage

Oxygen doping is an effective strategy for constructing high‐performance carbon anodes in Na ion batteries; however, current oxygen‐doped carbons always exhibit low doping levels and high‐defect surfaces, resulting in limited capacity improvement and low initial Coulombic efficiency (ICE). Herein, a stainless steel‐assisted high‐energy ball milling is exploited to achieve high‐level oxygen doping (19.33%) in the carbon framework. The doped oxygen atoms exist dominantly in the form of carbon‐oxygen double bonds, supplying sufficient Na storage sites through an addition reaction. More importantly, it is unexpected that the random carbon layers on the surface are reconstructed into a quasi‐ordered arrangement by robust mechanical force, which is low‐defect and favorable for suppressing the formation of thick solid electrolyte interfaces. As such, the obtained carbon presents a large reversible capacity of 363 mAh g −1 with a high ICE up to 83.1%. In addition, owing to the surface‐dominated capacity contribution, an ultrafast Na storage is achieved that the capacity remains 139 mAh g −1 under a large current density of 100 A g −1 . Such good Na storage performance, especially outstanding rate capability, has rarely been achieved before.