A high-performance solid-state electrolyte Na4ZrF8 with exceptional ionic conductivity and electrochemical and interfacial stability†
Abstract
We propose a promising sodium fluoride solid-state electrolyte (SSE), Na4ZrF8 (NZF), by using density functional theory combined with ab initio molecular dynamics simulations and grand potential phase diagram analysis. NZF exhibits excellent dynamic, thermal, and mechanical stability, along with a wide band gap of 8.18 eV. It delivers a high ionic conductivity of 3.5 mS cm−1 at 300 K, with a low activation energy of 0.22 eV and migration energy barriers of 0.23 eV in 2D channels and 0.36 eV in 3D channels. NZF also shows a broad electrochemical stability window (0.62–5.89) V, and an oxidation potential exceeding 5 V. Furthermore, it exhibits exceptionally lower interfacial reaction energies (<20 meV per atom) with polyanion cathodes, thus ensuring superior compatibility with high-voltage cathodes. These attributes highlight NZF's potential as a high-performance SSE for sodium-ion batteries and complement recent experimental advances in zirconium-based halide metal-ion conductors such as: Li4ZrCl4O2 [Nature Commun. 2023, 14, 3807], Li4ZrF8 [Adv. Energy Mater. 2022, 12, 2201808], NaxZrCl4+x and Na0.5ZrCl4F0.5 [Nature Commun. 2025, 16, 2808].
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers