TiO₂/GO-coated functional separator to suppress polysulfide migration in lithium-sulfur batteries

Lithium-sulfur batteries render a high energy density but suffer from poor cyclic performance due to the dissolution of intermediate polysulfides. Herein, a lightweight nanoporous TiO₂ and graphene oxide (GO) composite is prepared and utilized as an interlayer between a Li anode and a sulfur cathode to suppress the polysulfide migration and improve the electrochemical performance of Li/S batteries. The interlayer can capture the polysulfides due to the presence of oxygen functional groups and formation of chemical bonds. The hierarchically porous TiO₂ nanoparticles are tightly wrapped in GO sheets and facilitate the polysulfide storage and chemical absorption. The excellent adhesion between TiO₂ nanoparticles and GO sheets resulted in enhanced conductivity, which is highly desirable for an efficient electron transfer process. The Li/S battery with a TiO₂/GO-coated separator exhibited a high initial discharge capacity of 1102.8 mAh g^-1 and a 100th cycle capacity of 843.4 mAh g^-1, which corresponds to a capacity retention of 76.48% at a current rate of 0.2 C. Moreover, the Li/S battery with the TiO₂/GO-coated separator showed superior cyclic performance and excellent rate capability, which shows the promise of the TiO₂/GO composite in next-generation Li/S batteries.