Synergistic Promotion of Adsorption-Conversion for Lithium Polysulfides through Ion/Electron Coconductive Catalytic Triple-Phase Interface by the Geometric Torsion of Lithium Lanthanum Titanate Electrocatalyst

Rationally designing and constructing ionic/electronic coconductor electrocatalysts with adjustable active sites to enhance the redox kinetics of lithium-sulfur batteries (LSBs) in lean electrolyte conditions is a challenge. Herein, this study presents the promotion for lithium polysulfides (LiPSs) redox kinetics through the construction of ion/electron coconductive catalytic triple-phase interface using lithium lanthanum titanate/carbon (LLTO/C) nanofibers, which is due to manipulating the geometric torsion of BO₆ octahedron in LLTO. Experiments and theoretical calculations demonstrate that geometric torsion changes the coordination environment of O-Ti-O in LLTO and causes oxygen vacancy and lattice distortion. This enhances the local electronic state density, ion migration rate, and high catalytic activity of LLTO, thereby resulting in a synergistic effect for good chemisorption and rapid catalytic conversion of LiPSs. Therefore, when the modified separator is used, LSBs with the electrocatalyst realize a high discharge capacity of 1024 mA h·g^-1 at a high current rate of 2 C. Upon a high sulfur loading of 9 mg ·cm^-2 and a lean electrolyte/sulfur ratio of 4 μL· mg^-1, an acceptable areal capacity of 9.1 mA h· cm^-2 is achieved. This work provides a new perspective for the rational design of ionic/electronic coconductor catalysts for LSBs.