Design of “Sandwich” Structure Cellulose Based Separator Via Al2o3 Electrospinning for Sodium Ion Battery

Abstract

Cellulose is an attractive and sustainable separator material several key issues still hinder its practical application. In this study, a novel thin cellulose-polyacrylonitrile-alumina fibrous separator (LF-ALO) with a ‘sandwich’ structure was prepared via electrospinning on a cellulose-based paper separator (LF). Compared to LF, the LF-ALO separator demonstrates superior thermal dimensional stability, enhanced mechanical properties (19.7 MPa) and significantly higher electrolyte wettability (316%). This is attributed to the exceptional stability of alumina and the unique structure formed by spun fibers. The LF-ALO separator has excellent ion transference number (tNa+=0.85) and strong affinity for sodium ions effectively reduce the internal resistance of the battery and enhance charge/discharge efficiency. In addition, the composite separator features an aperture that is more appropriately sized, which can effectively mitigate the short-circuit phenomenon caused by excessively large LF apertures. Furthermore, the half-cell assembled with NFM as the cathode achieves a high capacity of 130 mAh g−1 at 0.1 C. This study presents a novel structural design strategy for separators with exceptional mechanical properties, favorable wettability, and high thermal stability, suitable for sodium-ion batteries.

Keywords: alumina, LF-ALO, electrospinning, sodium-ion batteries