“…As shown in Figure a, C (sp 2 ), C–H, C–O, OC–O, C–F, -CF 2 , and −CF 3 species can be found on the C-1s HRXPS of all three DPEs at around 284.3, 285.5, 286.3, 288.3, 289.8, 291.8, and 293.7 eV, respectively. − Noticeably, compared with the pristine DPE, the cycled DPEs show lower intensities of −CF 2 and −CF 3 and higher intensities of C–F, OC–O, C–O, and C–H, implying the degradation of the PTFE binder and oxidation of the carbonate electrolyte to form CEI layers on the surfaces of the DPEs. As displayed in Figure b, the pristine DPE exhibits a strong OC bond (531.5 eV) with an Li-O signal from the NMC lattice (529.0 eV); after cycling, the Li-O signal disappears, and an O-C peak at 533.1 eV is observed. − Such observations of O-1s HRXPS further confirm the formation of CEI on the DPE surface.…”