Preparation and performance of SPEI/PEI blending separator for enhanced lithium-sulfur battery

In this paper, a gel polymer electrolyte based on sulfonated polyetherimide (SPEI)/polyetherimide (PEI) blending separator has been fabricated through non-solvent-induced phase separation (NIPS) method. The performance of the SPEI/PEI blending separator is investigated through the morphology and electrochemical analysis. The addition of SPEI polymer has great effect on the morphology of separator’s top and bottom surface. When the SPEI mass ratio increases, the SPEI/PEI blending separator shows high porosity (up to 72.80%), ion conductivity (up to 2.63 mS cm −1 ), and low tensile strength (down to 7.98 MPa). The discharge specific capacity, capacity retention rate, and average capacity attenuation rate of lithium-sulfur battery using SPEI-2 (separator with the weight ratio of SPEI/PEI = 2:8) are 736.1 mAh g −1 , 57.2%, and 0.21% after 200 cycles, respectively. The result shows that the SPEI/PEI blending separator has lower capacity decays compared with SPEI-0 (separator with the weight ratio of SPEI/PEI = 0:10) and the commercial Celgard 2320 separator, which indicates that the existence of sulfonic acid group is conducive to the stability of the lithium-sulfur battery cycle. Therefore, it is concluded that the SPEI/PEI blending separator prepared by NIPS method is a potential separator for high-performance rechargeable lithium-sulfur battery.