Covalently Induced Grafting of C2N Nanoflakes onto Reduced Graphene Oxide with Dominant Pseudocapacitive Behaviors for a High-Rate Sodium-Ion Battery Anode

Nitrogen-doped carbon materials are widely used in sodium-ion batteries, but their uncertain doping structure, low nitrogen content, and sluggish sodiation kinetics hinder their practical application. Herein, thin-layer carbon nitride (C2N) with accurate nitrogen bonding location, ultrahigh nitrogen content, and an inherent nanohole structure is covalently confined onto the surface of reduced graphene oxide (C2N/rGO) via an SN1 nucleophilic substitution reaction combined with in situ polymerization. Benefiting from the abundant active sites, a short ion/electron transfer distance, and good conductivity, the C2N/rGO electrode delivers a capacity of 218.1 mAh g–1 after 1000 cycles at 1 A g–1. Moreover, the Na-storage mechanism is proven to be a capacity governed process through cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) methods. This work demonstrates a viable strategy to design an atomically ordered porous nitrogen-containing two-dimensional (2D) carbon material with excellent electrochemical performances.