A multifunctional separator for high-performance lithium-sulfur batteries.

Lithium-sulfur (Li–S) batteries attract much more attention over the past decades because of its high theoretical specific capacity (1675 mAh g−1). However, the rapid capacity decay caused by the shuttle effect of polysulfides greatly limits its practical applications. In this work, we prepared an acetylene black/γ-Al 2 O 3 /polypropylene composite separator in a friendly and simple way to improve the performance of Li–S batteries. The γ-Al 2 O 3 layer can block the polysulfides diffusion and simultaneously improve the thermal stability of the separator. The acetylene black layer can reduce interface impedance, improve the utilization of active materials and also further block the shuttle of the polysulfides. The Li–S batteries equipped with this composite separator show better cycling performance with an initial discharge capacity of 1096 mAh g−1 and a capacity decay as low as 0.08% per cycle for 500 cycles at 0.5 C (1 C = 1675 mA g−1) and rate performance with a reversible discharge capacity of 871 mAh g−1 at 3 C. Our work can be used for coming commercialization of Li–S batteries. A multifunctional separator is prepared by coating γ-Al 2 O 3 and acetylene black onto polypropylene for Li–S batteries. The redox kinetics of S is much increased and its shuttle is greatly depressed, leading to high performance Li–S batteries. Image 1 • Crucial problems for Li–S battery is the rate and cycling performance. • A modified separator can address the above problems. • This is done simple by coating Al2O3 and acetylene black. • Excellent rate and cycling behaviors are achieved for Li–S battery. [ABSTRACT FROM AUTHOR]