fig4

Figure 4. Electrochemical performance, structural evolution, and surface information of N/P-MC@RGO anode during the K⁺ storage. (A) Cycling performance at a rate of 0.5 A g^-1. (B) EIS spectra achieved after different cycles under a constant charging/discharging rate of 0.2 A g^-1. (C) Ex situ Raman spectra, (D) C1s and K2p, (E) O1s XPS spectra for N/P-MC@RGO during the different charging/discharging stages. (F) TEM image, (G) ADF-STEM image, and the corresponding EDS mapping of (H) C-K, (I) O-K, and (J) K-K for N/P-MC@RGO after the long-term cycles.