High Loading Sulfur Cathodes by Reactive-Type Polymer Tubes for High-Performance Lithium-Sulfur Batteries

Simultaneously attaining high gravimetric energy density (E_g) and volumetric energy density (E_v) in lithium-sulfur (Li–S) batteries is a longstanding challenge that has to be solved for practical application, which demands breakthroughs in electrode materials with optimized functionality and structure. Herein, anthraquinone-containing, reactive-type polymer tubes (PQT) that can be used to regulate the redox chemistry of sulfur species are designed and prepared for practical Li–S batteries. PQT favors a similar redox potential window as sulfur, which effectively facilitates the immobilization and conversion of sulfur species through a reversible lithiation/delithiation process. Its tubular structure and high tap density is vital to the fabrication of intact electrode with high sulfur loading and minimizing electrolyte intake during battery operation. With all these contributions, Li–S battery with PQT/S cathode exhibits a stable cycling capacity (73% at 2.0 C over 1000 cycles), remarkable rate performance (514.2 mAh g⁻¹ at 10 C), and a high areal capacity of 7.20 mAh g⁻¹ with high sulfur loading under lean electrolyte condition. More importantly, the assembled Li–S pouch cell delivers an E_g of 329 Wh kg⁻¹ and an E_v of 401 Wh L⁻¹, which meets the requirement for practical operation.