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 BO 6 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.