Design a Catalytic Cathode Material with Abundant Oxygen Vacancies to Accelerate the Kinetics of Lean‐Electrolyte Lithium‐Sulfur Batteries

Abstract

Lean-electrolyte lithium-sulfur (LiÀ S) batteries are confronted with sluggish reaction kinetics, which required high catalytic materials to improve electrochemical performance. Herein, high catalytic-activity Ce-doped TiO 2 nanoparticles were combined into reduced graphene oxides (rGO) as the sulfur cathode (Cedoped TiO 2 /rGO/S). The impact of doping amounts of Ce on oxygen vacancies (OVs) was studied. Among the different Ce doping amounts, the 0.4 wt% Ce doping TiO 2 (0.4 CeÀ TiO 2 ) exhibits the best catalysis and adsorption for Li 2 S 6 due to the most OVs in 0.4 CeÀ TiO 2 . Rich OVs can provide more active sites for sulfur adsorption and present stronger catalytic activity to polysulfides. With an electrolyte to sulfur (E/S) ratio of 7 μL mg S À 1 , the 0.4 CeÀ TiO 2 /rGO/S exhibits the best electrochemical capability when compared with TiO 2 /rGO/S and rGO/S. It has a high capacity of 1421.9 mAh g À 1 at 0.1 C (1 C = 1675 mA g À 1 ), and excellent rate performance. The 0.4 CeÀ TiO 2 / rGO/S also has a higher capacity and more stable cyclic performance than TiO 2 /rGO/S when the temperature elevates to 60 °C.