Edge-Nitrogen Enriched Porous Carbon Nanosheets Anodes with Enlarged Interlayer Distance for Fast Charging Sodium-Ion Batteries

The application of nitrogen-doped porous carbon for sodium-ion batteries (SIBs) has attracted tremendous attention. Herein, a series of edge-nitrogen enriched porous carbon nanosheets (ENPCNs) are synthesized by annealing g-C3N4 and glucose in a sealed graphite crucible at different temperatures (T = 700, 800, and 900 degrees C). Surprisingly, under the closed thermal treatment condition, the ENPCNs-T possess a high N-doping level (>12.62 at%) and different carbon interlayer distance ranging from 0.429 to 0.487 nm. By correlating the carbon interlayer distance with the N configurations of ENPCNs-T materials, a reasonable perception of the important influence of pyrrolic N on the increase of carbon interlayer distance is proposed. When applied as anode materials for SIBs, the ENPCNs-800 exhibits a remarkable capacity (294.1 mAh g(-1) at 0.1 A g(-1)), excellent rate performance (132.8 mAh g(-1) at 10 A g(-1)), and outstanding cycle life (180.6 mAh g(-1) at 1 A g(-1) after 1000 cycles with a capacity retention of 104.7%). Meanwhile, the characterizations of cyclic voltammetry, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy demonstrate that the edge-nitrogen doping and enlarged carbon interlayer distance improve the capacity and fast charging performance of ENPCNs-800. Considering the detailed investigation of the Na+ storage mechanism and excellent electrochemical performance of ENPCNs-800, this work can pave a new avenue for the research of SIBs.

Automated summary

This study successfully synthesized a series of edge-nitrogen enriched porous carbon nanosheets (ENPCNs) to address the drawbacks of anode materials in sodium-ion batteries (SIBs). Among them, ENPCNs-800 exhibited excellent capacity, rate performance, and cycle life, possibly improved by edge-nitrogen doping and enlarged carbon interlayer distance.