Insight into structural, electronic, and chemical bonding properties of PEO-PEG-LiI polymer electrolyte: A first-principles investigation

Abstract

Quantum chemistry-based codes and methods provide valuable computational tools to study the atomic and molecular structure of any system. This paper provides insights into the electronic and structural properties of polyethylene oxide (PEO) and polyethylene glycol (PEG) based solid polymer electrolyte incorporated with lithium iodide as ion-conducting species using first principle method. PEO shows insulator characteristics with a broad bandgap of 5.2 eV which decreased significantly to 3.19 eV in PEO-PEG-LiI. The wide forbidden energy band gap of PEO-PEG-LiI concludes that conductivity in polymer electrolytes is predominantly ionic rather than electronic. The presence of hydrogen bonding between PEG and PEO shows their amazing compatibility. Hirschfield population analysis (HPA) quantify the interactions involved within the structure and explains the interaction of Li-ion with ether group of PEO. Overlapping of wavefunctions of C, O and H atoms in polymers proves the existence of partial ionic and partial covalent bonding among them.