Multimodal Capturing of Polysulfides by Phosphorus-Doped Carbon Composites for Flexible High-Energy-Density Lithium-Sulfur Batteries

Abstract

The widespread adoption of Li-ion batteries is currently limited by their unstable electrochemical performance and high flammability under mechanical deformation conditions and a relatively low energy density. Herein, high-energy-density lithium-sulfur (Li-S) batteries are developed for applications in next-generation flexible electronics and electric vehicles with long cruising distances. Freestanding high-S-loading carbon nanotubes cathodes are assembled with a phosphorus (P)-doped carbon interlayer coated on commercial separators. Strategies for the active materials and structural design of both the electrodes and separators are highly efficient for immobilizing the lithium polysulfides via multimodal capturing effects; they significantly improve the electrochemical performance in terms of the redox kinetics and cycling stability. The foldable Li-S cells show stable specific capacities of 850 mAh g(-1) over 100 cycles, achieving high gravimetric and volumetric energy densities of 387 Wh kg(cell)(-1) and 395 Wh L-cell(-1), respectively. The Li-S cells show highly durable mechanical flexibilities under severe deformation conditions without short circuit or failure. Finally, the Li-S battery is explored as a light-weight and flexible energy storage device aboard airplane drones to ensure at least fivefold longer flight times than traditional Li-ion batteries. Nanocarbon-based S cathodes and P-doped carbon interlayers offer a promising solution for commercializing rechargeable Li-S batteries.