fig5

Figure 5. Interfacial chemistry with different separators. (A) Compositions of the SEI on Cu foil substrates after five cycles at the current of 0.5 mAh·cm^-2 and corresponding XPS patterns by Li 1s, F 1s and C 1s. TEM characterization of the SEI on Cu foil after five cycles at the current of 0.5 mAh·cm^-2 with different separators: (B) PP, (C) PEI, (D) PEI-EDA. TEM characterization of the LFP cathode after one cycle with different separators: (E) PP, (F) PEI, (G) PEI-EDA. OLEMS of Li|| LFP cells with different separators: (H) PP, (I) PEI, (J) PEI-EDA. (K) Li stripping/plating behavior with PP, PEI and PEI-EDA separators. SEI: Solid electrolyte interphases; XPS: X-ray photoelectron spectroscopy; PEI-EDA: ethylenediamine grafting polyetherimide; PEI: polyetherimide; PP: polypropylene; TEM: transmission electron microscope; OLEMS: online electrochemical mass spectroscopy; LFP: LiFePO_4.