Regulatory mechanism of inorganic fillers on Zn2+ transport in PEO–Zn(TFSI)2 electrolyte within all-solid-state zinc-ion batteries

Abstract

All-solid-state zinc-ion batteries (ZIBs) require electrolytes that deliver both high ionic conductivity and high safety; however, the Zn²⁺ migration mechanisms in composite solid electrolytes remain unclear. In this work, we combine molecular dynamics (MD) simulations with density functional theory (DFT) calculations to study Zn²⁺ transport in a PEO-Zn(TFSI)₂ matrix and in its composites containing SiO₂, ZnPS₃, and a ZnPS₃/MoS₂ hybrid filler, with a particular focus on bulk plasticization and interfacial transport pathways. The results show that SiO₂ delivers a modest low-temperature gain primarily by reducing crystallinity. ZnPS₃ weakens ZnO coordination while forming a Zn-P-dominated interfacial network and a space-charge layer, thereby enhancing diffusion across a broad temperature window. Surface states on ZnPS₃(001) induce electron accumulation that electrostatically drives Zn²⁺ enrichment at the interface. The introduction of MoS₂ further enhances the interfacial dipole and geometric connectivity, resulting in a relative increase of approximately 1.5–2.4 times in the MSD slope at medium-to-high temperatures compared to PEO + ZnPS₃. MD and DFT calculations demonstrate that the synergistic effect of chemically driven coordination exchange and geometrically guided epitaxial channels substantially enhances zinc ion mobility within the electrolyte.