Synthesis, Fabrication and Characterisation of DOPO-based Electrospun Polyimide Separator for Lithium Metal Battery

This study describes the synthesis and electrospinning fabrication of the DOPO-based polyimide (ES-DOPO-60) separator. The ES-DOPO-60 separator was evaluated for its thermal, mechanical, wettability, solvent-absorption, and porosity characteristics. The above-mentioned qualities of ES-DOPO-60 have been analysed and found to demonstrate superior separator characteristics in comparison to the traditional Celgard 2500. Furthermore, the ES-DOPO-60 non-woven fabric was immersed in a 1 M LiPF6/EC: DMC solution for 72 hours and subsequently used for electrochemical characterisation. The ES-DOPO-60 demonstrated a solvent uptake of 525%, significantly surpassing that of the traditional Celgard 2500 separator, resulting in an exceptional ionic conductivity of 1.36 × 10-4 Scm-1 at 30 °C. Additionally, the ES-DOPO-60 separator exhibited a wider electrochemical stability window of 5V, facilitating the use of higher-energy-density cathodes for advanced lithium-metal battery applications. The lithium transference number of ES-DOPO-60 is calculated to be 0.478, which is relatively superior to that of the Celgard 2500 system, which may help in dendritic suppression. These exceptional thermal, mechanical, and electrochemical characteristics of the ES-DOPO-60 separator make it a promising candidate for their potential applications in lithium metal battery systems.