fig4

Figure 4. Structural and surface evolution of HC125@ Co₃O₄ during cycling. (A) Ex situ XRD of the pristine electrode and HC125@Co₃O₄ electrode at different potentials during the second cycle at 0.05 A g^-1 (C/D mean charge/discharge), and (B) the corresponding potential and GCD curves. Ex situ XPS spectra of (C) Co_2p3/2 and (D) C1s for HC125@Co₃O₄ electrode in pristine, fully discharged-0.01 V and charged-3 V states during the second discharging/charging cycles at 0.05 A g⁻¹. (E) RDF and coordination number of Na⁺-PF₆^- in the presence of HC, Co, CoO and Co₃O₄.