Fig. 5: XPS analysis of hard carbon anodes.
From: Consummating ion desolvation in hard carbon anodes for reversible sodium storage
a, b XPS spectra of C 1s with different etching times (0–25 min) collected from the cycled hard carbon in 1 M NaPF6-EC/DEC electrolytes (a) and corresponding fitting results (b) at etching time of 0, 0.5, 5.5, 12, and 25 min. c, d XPS spectra of C 1s with different etching times (0–25 min) collected from the cycled hard carbon in 1 M NaPF6-G2 electrolytes (c) and corresponding fitting results (d) at etching time of 0, 0.5, 5.5, 12 and 25 min. e, f The C 1s (e) and Na 1s (f) peak position changes of cycled hard carbons with etching time. The gray line shows the Na 1s peak position changes of hard carbons immersed in ether electrolytes. g The F 1s signal intensity changes with etching time.
