Wafer-biscuits-like few-graphene-layers carbon with N, P, S triple-doping for efficient and stable sodium-ion storage

Carbon-based materials are one of the most attractive anodes for sodium-ion batteries because of their wide availability, facile synthesis, and low cost. However, rational designing carbon-based architecture towards upgrading the electrochemical performance of anodes for sodium storage has been a great challenge. Herein, we prepared N, P, S triple-doped few-graphene-layers carbon with expanded interlayer spacing via a scalable template approach. The few-graphene-layers carbon negatively replicates the structure of the layered template to generate a wafer-biscuit-like architecture, which prevents the restack of carbon nanosheets. The interlayer spacing and heteroatom contents of wafer-biscuit-like carbon architecture can be modulated by varying carbonization temperatures. Consequently, the optimum carbon anode delivers a high reversible capacity of 329 mAh g−1, good rate capability, and long-term stability of 300 cycles at 1 A g−1. Furthermore, the sodium storage mechanism of wafer-biscuit-like carbon anodes has been systematically explored.