Synergistic effects of halloysite nanotubes in electrospun PVDF-HFP separator for advanced sodium ion battery

Abstract

Sodium-ion batteries (SIBs) emerge as a sustainable option for energy storage, standing out as a cost-effective and resource-abundant substitute to lithium-ion batteries (LIBs). However, the development of sustainable SIBs necessitates the innovation of separator materials capable of enhancing battery efficiency and safety. This research highlights the fabrication and characterization of a novel separator made up of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) filled with halloysite nanotubes (HNTs) via the electrospinning technique for SIBs application. The electrospun composite separator was systematically fabricated and comprehensively characterized to investigate its morphological, electrochemical, thermal and mechanical properties. Field emission scanning electron microscopy (FESEM) analysis revealed a well-dispersed HNTs network within the PVDF-HFP matrix, resulting in a fibrous structure with enhanced mechanical strength (23.6 MPa). Electrochemical performance was evaluated through electrochemical impedance spectroscopy (EIS) and cyclic charge-discharge (GCD). The halloysite filled PVDF-HFP separator demonstrated higher ion conductivity (2.11 mS cm⁻¹) and electrochemical stability at ambient temperature, leading to enhanced battery performance, including higher specific capacity (171 mA h g⁻¹) at 0.1C-rate. Thermal stability studies confirmed the improved thermal resistance of the composite separator, crucial for maintaining structural integrity under high temperatures. The incorporation of HNTs into the structure of PVDF-HFP contributes to the development of robust and efficient separators for SIBs, facilitating the development of sustainable and scalable energy storage.