Structure and Dynamics of Ions in a Poly(ethylene oxide) Matrix Near a Graphite Surface

Abstract

Solid polymer electrolytes are being explored as replacements for organic electrolytes in lithium-ion batteries due to their less flammable nature and high mechanical strength. However, challenges remain, such as low ionic conductivity, and significant interfacial impedance with electrodes. Understanding the structure and dynamics of ions within polymer electrolytes and near the anode is crucial for enhancing battery performance and safety. In this study, the structural and dynamic properties of lithium cation (Li⁺) and bis(trifluoromethane sulfonyl)imide anion (TFSI⁻) in poly(ethylene oxide) matrix are examined in bulk PEO-LiTFSI electrolyte and in the presence of a graphite surface using molecular dynamics simulations. The findings suggest that the presence of graphite surface does not affect the coordination of oxygen atoms around the Li⁺ ions. Results also show that the dynamics of the ions and ether oxygen is hindered near the graphite surface compared to the region away from the graphite surface.