TiO₂-decorated porous carbon nanofiber interlayer for Li-S batteries

Lithium-sulfur (Li-S) batteries are the most promising energy storage systems owing to their high energy density. However, shuttling of polysulfides detracts the electrochemical performance of Li-S batteries and thus prevents the commercialization of Li-S batteries. Here, TiO₂@porous carbon nanofibers (TiO₂@PCNFs) are fabricatedviacombining electrospinning and electrospraying techniques and the resultant TiO₂@PCNFs are evaluated for use as an interlayer in Li-S batteries. TiO₂nanoparticles on PCNFs are observed from SEM and TEM images. A high initial discharge capacity of 1510 mA h g^-1is achieved owing to the novel approach of electrospinning the carbon precursor and electrospraying TiO₂nanoparticles simultaneously. In this approach TiO₂nanoparticles capture polysulfides with strong interaction and the PCNFs with high conductivity recycle and re-use the adsorbed polysulfides, thus leading to high reversible capacity and stable cycling performance. A high reversible capacity of 967 mA h g^-1is reached after 200 cycles at 0.2C. The cell with the TiO₂@PCNF interlayer also delivers a reversible capacity of around 1100 mA h g^-1at 1C, while the cell without the interlayer exhibits a lower capacity of 400 mA h g^-1. Therefore, this work presents a novel approach for designing interlayer materials with exceptional electrochemical performance for high performance Li-S batteries.