Enhanced Ionic Diffusion via Refined Pillared 1D Channels for Sodium Metal Batteries

Abstract

In sodium-metal batteries (SMBs), the tunability of metal-organic frameworks (MOFs) pore structures in electrolytes enhances sodium ion transport and anion selectivity. However, the underlying mechanism of these pore structures, especially on ion transport and anion filtration, Dremains unclear. Herein, two zinc-based azole hybrid frameworks (AHF) featuring pillared 1D channels are synthesized. The refined MOF-based electrolyte, BPDC@PH, exhibits an ionic mobility number of 0.87 and an ionic conductivity of 7.74 × 10⁻⁴ S cm⁻¹ at 35 °C, with cycling stability exceeding 1000 hours at 1.0 mA cm⁻², which is comparable to existing MOF-based electrolytes. Density functional theory calculations and molecular dynamics simulations reveal that the enlarged AHF-BPDC channels enhance Na⁺ diffusion and TFSI⁻ adsorption, with a diffusion coefficient of 5.733 × 10⁻¹⁰ m² s⁻¹Time-of-flight secondary ion mass spectrometry (TOF-SIMS) conforms efficient NaTFSI transport and rapid NaF deposition, ensuring 1000-cycle stability and over 99% efficiency. The refined MOFs with pillared 1D channels present a promising strategy for developing advanced ssGPEs for highly efficient SMBs.