Polyaniline/rGO/S composite cathode with GO modified separator for lithium sulfur battery: A multipronged approach to tackle the shuttle effect

Lithium-sulphur batteries (LSBs) are a promising candidate for the next generation of high energy density, safe, green and affordable batteries but their practical utilization is hindered by several roadblocks including low cycle life, fast capacity fade, low sulfur utilization due to insulating nature of sulfur and “polysulfide shuttle”. This work employs multiple strategies to circumvent the aforementioned issues like utilizing (i) a reduced graphene oxide (rGO) conducting carbon framework for improving conductivity and mechanical stability of cathode, (ii) polyaniline conducting polymer with polar groups to restrain soluble lithium polysulfides (LiPS) by physisorption/chemisorption (iii) separator modification with graphene oxide to act as a second barrier layer to suppress LiPS migration and support the cathode current collector to enhance sulfur utilization. The combination of these strategies led to a LSB cell that exhibited high initial capacity, low capacity fade and improved lithium ion diffusion as well as lowered cell impedance. The synthesized cathode composite of PANI-rGO-sulfur (PGS) was characterized by several techniques like power x-ray diffraction, scanning electron microscopy, thermogravimetry etc. Electrochemical characterization of cells was performed by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic cycling. The coin cell delivered a superior initial capacity of 807 mAh/g at 100 mA/g current density. Upon cycling at a high current density of 1A/g it delivered a capacity of 478 mAh/g with excellent stability for 500 cycles and lower capacity fade of 0.02% per cycle.