Molecular dynamics investigation of functionalized and unfunctionalized Al2O3 nanofillers dispersed in P(EO)8/LiClO4: Polymer solid electrolytes

Abstract

Solid Polymer Electrolyte (SPEs) based on P(EO) 8 /LiClO 4 are promising for Lithium-Metal Batteries (LMBs), but their room-temperature performance remains limited by low Li + mobility and excessive polymer crystallinity. In this study, classical Molecular Dynamics (MD) simulation was used to investigate structural and transport properties of three systems: System 1: pristine P(EO) 8 /LiClO 4 , System 2: Unfunctionalized Al 2 O 3 nanofillers, and System 3: SO 3 H- functionalized Al 2 O 3 nanofillers. We evaluated Li + diffusion, conductivity, transference number of Li + , structure factor intensity, and interfacial adhesion with Li (100). The P(EO) 8 /LiClO 4 / Al 2 O 3 -SO 3 H (2 wt%) showed the best performance, with the highest Li + diffusion coefficient (8.11 × 10 −9 cm 2 /s), conductivity (1.69 × 10 −4 S/cm), and transport number (0.76), along with strong interfacial adhesion (−4491 Kcal/mol). Structure factor intensity revealed a sharper peak at q ≈ 0.12 Å −1 , indicating increased intermediate-range order. However, simulations also revealed that a very high Al₂O₃-SO₃H content (> 5 wt%) induces excessive intermediate-range ordering, with a decrease in Li + ion diffusion. These results confirm that the unique conductivity and compatibility of the polymer-electrolyte surface are likely to prevent the crystallization of solid polymers on the PEO base. • Acid-functionalized Al₂O₃-SO₃H (2 wt%) enhanced Li⁺ transport in PEO electrolytes. • Optimized composite: Li⁺ diffusion 8.11 × 10⁻⁹ cm²/s, conductivity 1.69 × 10⁻⁴ S/cm, t⁺ = 0.76. • Excess nanofiller (>5 wt%) induced intermediate-range ordering, reducing Li⁺ mobility. • Nanofillers reinforced interfacial adhesion with Li (100), improving compatibility. • Molecular insights for designing high performance PEO-based polymer electrolytes.