Entrapment of polysulfides by a Ketjen Black & mesoporous TiO2 modified glass fiber separator for high performance lithium-sulfur batteries

Abstract The application of lithium-sulfur batteries is limited due to low electric conductivity of sulfur and “shuttle effect” caused by diffusion of soluble polysulfides to the anode. In this study, self-made mesoporous TiO 2 and commercial Ketjen Black are mixed to obtain a composite material, which is then coated on glass fiber membrane through a slurry method. The modified glass fiber membrane is used as a functional separator in lithium-sulfur battery. The batteries using modified separator show a high initial discharge specific capacity of 1130.3mAh g −1 at 0.2C and an excellent cycling stability of 991.8mAh g −1 even after 60 cycles, and initial discharge specific capacity of 996.7mAh g −1 at 0.5C and 804.3mAh g −1 even after 100 cycles. The improved performance of the battery can be ascribed to effective adsorption of mesoporous TiO 2 to the soluble polysulfides and limit diffusion of the reaction intermediate to anode side. Moreover, the excellent electrical conductivity of Ketjen Black coated on the surface of glass fiber membrane can reduce the internal resistance, activate the absorbed polysulfides, and increase the specific capacity of the lithium-sulfur battery. It is believed that mesoporous TiO 2 and Ketjen Black modified glass fiber membrane effectively suppresses the “shuttle effect” during the cycling and provides a promising approach for high-performance lithium-sulfur batteries.