The effect of nitrogen-rich ionic liquid [EMIMDCA] on the electronic structure of solid polymer electrolyte (PEO-LiTFSI).

Abstract

In our work, the ab-initio methods based on density functional theory (DFT) formalism are used to investigate the effect of nitrogen-rich ionic liquid (EMIMDCA; 1-ethyl-3-methylimidazolium dicyanamide) on the electronic structure of SPE (solid polymer electrolyte) (PEO-LiTFSI) electrolyte with B3LYP method and LANL2DZ basis set. The differences in energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), i.e., energy gap ([Formula: see text]) of the PEO, [EMIMDCA], SPE, and ionogel (IG), are found 5.74, 6.59, 3.25, and 2.80eV, respectively. In SPE, the reduced band gap ([Formula: see text]) is due to the transportation of cation of LiTFSI (Li+ ion). Finally, the reduced band gap of IG confirms that IL enhances the transportation of cation of LiTFSI (Li+ ion) through the oxygen atom of PEO. The global and local chemical descriptors and electrochemical stability windows (ESWs) are calculated using the HOMO-LUMO energy levels. Partial charge analysis is studied by Mulliken population analysis and molecular electrostatic potential surface.