Graphene Oxide Block Derived Edge‐Nitrogen Doped Quasi‐Graphite for High K+ Intercalation Capacity and Excellent Rate Performance

Abstract

AbstractThe intercalation capacity at low potential of carbon‐based anode plays a significant role for developing potassium ion batteries (PIBs) with high energy density. However, the inferior rate and cyclic performance caused by repeated insertion/extraction of large K+ tremendously restricts the practical application of PIBs. Herein, a quasi‐graphite structure with abundant edge‐nitrogen doping, micropores structure, and enhanced graphite nanodomains via in situ polymerization of oligoaniline in‐between graphene oxide blocks and subsequent carbonization is proposed. The macro‐ordered multilayered structure with micro‐ordered graphite nanodomains can provide efficient K+ insertion/extraction channels, thus greatly increasing the intercalation capacity at low potentials. Moreover, the high edge‐nitrogen doping (97%) is of great importance for improving K+ transfer kinetics, particularly at high current densities. As a result, the anode exhibits a high discharge capacity below 0.5 V (303 mAh g−1 at 0.05 A g−1), outstanding rate performance (113 mAh g−1 at 5 A g−1), and long‐term cycle stability (176 mAh g−1 at 1 A g−1 after 2000 cycles). The K+ intercalation mechanism and enhanced kinetics are systematically probed by in situ Raman spectroscopy, ex situ X‐ray diffraction (XRD) spectra, and theoretical calculations. This results demonstrate that the construction of quasi‐graphite with heteroatom doping is feasible for large ion storage.