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

Abstract

The 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.

Self-Propagating Fabrication of a 3D Graphite@rGO Film Anode for High-performance Potassium-Ion Batteries

“…The pore size distribution curve in Figure 2e confirms the well-developed mesopores in 3D-G@rGO with pore sizes ranging from 1 to 100 nm, which can be conducive for ion transportation and improve the rate capability of graphite anode. 46,47 Fourier transform infrared (FTIR) spectra of 3D-G@rGO-5:5 shows the appearance of absorption peaks at 1246, 1574, and 1732 cm −1 corresponding to the stretching vibrations of C−O−C, C�C, and C�O/O�C−OH, 48 respectively, as shown in Figure S2. X-ray photoelectron spectroscopy (XPS) was further conducted to quantitatively analyze the oxygencontaining functional groups, and the oxygen content in 3D-G@rGO is determined to be approximately ∼12.0 wt % (Figure 2f).…”

“…Fourier transform infrared (FTIR) spectra of 3D-G@rGO-5:5 shows the appearance of absorption peaks at 1246, 1574, and 1732 cm –1 corresponding to the stretching vibrations of C–O–C, CC, and CO/OC–OH, respectively, as shown in Figure S2. X-ray photoelectron spectroscopy (XPS) was further conducted to quantitatively analyze the oxygen-containing functional groups, and the oxygen content in 3D-G@rGO is determined to be approximately ∼12.0 wt % (Figure f).…”

Recent advances in rational design for high-performance potassium-ion batteries

“…455 Furthermore, doping is often accompanied by a widening of the interlayer spacing, which promotes the insertion/extraction of potassium ions in the carbon anode, thereby improving the potassium storage capacity. 465–470 In 2016, Share et al 377 successfully increased the potassium storage capacity of graphite from the theoretical maximum value of 279 mA h g −1 to 350 mA h g −1 by doping nitrogen into few-layer graphene (Fig. 35a and b).…”

In Situ Chemical Modulation of Graphitization Degree of Carbon Fibers and Its Potassium Storage Mechanism

“…[ 7a ] Although some progress has been achieved, the volume expansion during repeated cycling remains not negligible and the capacity of graphite anode is still unsatisfactory (<100 mA h g −1 at 1 A g −1 ), with inadequate cycling lifetime (<200 cycles). [ 11 ] At the same time, it remains a challenge to balance the high capacity and initial coulombic efficiency (ICE).…”