Two-in-one separator capturing and reutilizing polysulfides for high performance lithium-sulfur batteries

The lithium-sulfur battery (LSB) is highly attractive as a next-generation class of batteries because of its high theoretical energy density and cost-effectiveness. The LSB has not yet been commercialized, however, due to performance fading caused by the severe shuttle reactions of polysulfides. Herein, we have strategically designed a multifunctional composite separator by coating ordered mesoporous Mn2O3 (m-Mn2O3) together with highly conductive Super P (SP) on polyethylene (PE) separators. The coating layer is intentionally designed to cause spontaneous chemisorption and reutilization of dissolved polysulfides, thereby enhancing the reversibility and cycling stability of LSBs. The m-Mn2O3 offers fast chemisorption of polysulfides dissolved in electrolyte through the features of its high polarity and large specific surface area. Meanwhile, the highly conductive SP can physically mitigate the crossover of polysulfides and reversibly reutilize the polysulfides during cycling. In practice, the LSB cell assembled with the separator coated with m-Mn2O3 and SP delivers a high reversible capacity of 553 mAh g−1 at a current density of 0.5 C, even after 300 cycles. We argue that the integration of functional m-Mn2O3 and SP (“two-in-one”) on the PE separator would be a practical solution to minimize the undesirable loss of reversibility and maximize the cycling stability of LSBs.