Fig. 6. XPS fitting results for the SEI layer in different electrolytes. (a) C 1s, (b) O 1s, and (c) F 1s, (d) the molecular energy levels of the HOMO and the LUMO of the solvent molecules and potassium salts: FSI− and DME in the DME electrolyte; FSI− in the EC/DEC electrolyte and KPF6 in the EC/DEC electrolyte, and (e) SEI species ratio.
