Synergistic Effect of CNT-TiO₂ Catalyst and 3D Electrode Architecture for Electrochemical Performance in Lithium-Sulfur Batteries

Abstract

Lithium-sulfur batteries (LSBs) are a potential electrochemical storage system with high capacity (1675 mAh g-1) and energy density (∼2600 Wh kg-1). The poor conductivity of sulfur, polysulfide shuttle effect, and volume expansion of the sulfur cathode are the main hurdles to their commercialization. To mitigate these issues, this work represents a rational composite of hybrid multiwalled carbon nanotubes (MWCNT) -TiO2 high surface area carbon-sulfur composite (CTHS) onto a 3D carbon fiber (CF) based free-standing electrode (CTHS@CF) architecture. TiO2 can effectively anchor the polysulfides by chemical bonding and improve cyclability. MWCNTs and CFs are the effective electron transport materials that accelerate the redox kinetics of polysulfides. The electrochemistry of CTHS@CF reveals an excellent discharge capacity of 910 mAh g-1 (1st cycle) at 100 mA g-1 compared to the conventional aluminum-coated (CTHS@Al) of 532 mAh g-1. The CTHS@CF (at 300 mA g-1) displays 514 mAh g-1 (initial discharge) capacity with 83% capacity retention up to 100 cycles, whereas CTHS@Al shows 394 mAh g-1 with 44% capacity retention. Combining 3D electrode architecture with metal oxide (TiO2) plays a vital role in the electrochemistry of LSBs by improving the stability of the battery's cycle life and overall energy density.