ZIF‐67 In Situ Grown PAN Spun Membrane Gel Electrolyte for Sodium‐Sulfur Batteries

ABSTRACT Sodium‐sulfur (Na‐S) batteries are promising next‐generation energy storage systems due to their high theoretical energy density and low cost. Nevertheless, two critical challenges hinder their practical application: (1) safety risks arising from sodium dendrite growth, and (2) energy loss (via polysulfide shuttle effects and capacity fade) leading to rapid performance degradation. In this work, we address these issues with a composite gel polymer electrolyte (GPE), which is fabricated by integrating metal–organic framework–modified polyacrylonitrile (PAN) electrospun membranes with polyethylene oxide (PEO) denoted as PEO/PAN@ZIF‐67 (PPZ). Pure PAN spun film with PEO is named PAN/PEO (PP). The resulting electrolyte exhibits an ionic conductivity of 4.2 × 10 ⁻⁴ S cm ⁻¹ and an enhanced Na ⁺ transference number () of 0.384. Symmetric Na cells demonstrate stable cycling for 400 h with a low overpotential of 130 mV. Moreover, we used sulfurized polyacrylonitrile (SPAN) as the cathode material. The SPAN/PPZ GPE/Na full cell retains a high reversible capacity of 691 mAh g ⁻¹ after 500 cycles at 1 A g ⁻¹ with minimal capacity decay. Both Na/PPZ GPE/Na and SPAN/PPZ GPE/Na configurations exhibit exceptional performance at 50°C, attributed to the dual functionality of the composite GPE: effective suppression of polysulfide shuttling and stabilization of the Na anode interface, thereby enhancing safety and cycling stability.