Synergistic Adsorption-Catalytic Sites TiN/Ta₂O₅ with Multidimensional Carbon Structure to Enable High-Performance Li-S Batteries

Abstract

Lithium-sulfur (Li-S) batteries are deemed to be one of the most optimal solutions for the next generation of high-energy-density and low-cost energy storage systems. However, the low volumetric energy density and short cycle life are a bottleneck for their commercial application. To achieve high energy density for lithium-sulfur batteries, the concept of synergistic adsorptive–catalytic sites is proposed. Base on this concept, the TiN@C/S/Ta2O5 sulfur electrode with about 90 wt% sulfur content is prepared. TiN contributes its high intrinsic electron conductivity to improve the redox reaction of polysulfides, while Ta2O5 provides strong adsorption capability toward lithium polysulfides (LiPSs). Moreover, the multidimensional carbon structure facilitates the infiltration of electrolytes and the motion of ions and electrons throughout the framework. As a result, the coin Li-S cells with TiN@C/S/Ta2O5 cathode exhibit superior cycle stability with a decent capacity retention of 56.1% over 300 cycles and low capacity fading rate of 0.192% per cycle at 0.5 C. Furthermore, the pouch cells at sulfur loading of 5.3 mg cm−2 deliver a high areal capacity of 5.8 mAh cm−2 at low electrolyte/sulfur ratio (E/S, 3.3 μL mg−1), implying a high sulfur utilization even under high sulfur loading and lean electrolyte operation.

Keywords

• lithium-sulfur batteries
• catalyst
• TiN/Ta₂O₅
• multidimensional carbon