Redefining the lithium-sulphur battery performance with a lithium lanthanum titanate-graphene modified separator

To suppress the lithium polysulfides (LPSs) dissolution and associated shuttle effect in Lithium-Sulfur Batteries (LSBs), we have functionalized the celgard separator with lithium lanthanum titanate-graphene nanoplatelets (LLTO-G), which offer LPSs immobilization capability and accelerated catalytic conversion kinetics. The LLTO-G composite was synthesized by solid-state route followed by ultrasonication. The assembled cell, optimized with an electrolyte-to-sulfur (E/S) ratio of 6–8 μL/mg demonstrated an initial discharge capacity of 1216 mAh/g at 0.1 C rate, retaining a capacity of 69 % after 100 cycles. Cyclability was investigated at a sulfur loading of 3 mg/cm² (0.5 C rate) over 200 cycles, resulting in an initial discharge capacity of 741 mAh/g. Furthermore, the device shows stable shuttle current, enhanced Li-ion diffusion, low coulombic efficiency loss, and minimal self-discharge. The electrochemical outcomes showcase the functionalized separator design as a viable strategy for developing high-performance LSBs.