A Multifunctional Separator Enables Safe and Durable Lithium/Magnesium-Sulfur Batteries under Elevated Temperature

Rechargeable metal-sulfur batteries encounter severe safety hazards and fast capacity decay, caused by the flammable and shrinkable separator and unwanted polysulfide dissolution under elevated temperatures. Herein, a multifunctional Janus separator is designed by integrating temperature endurable electrospinning polyimide nonwovens with a copper nanowire-graphene nanosheet functional layer and a rigid lithium lanthanum zirconium oxide-polyethylene oxide matrix. Such architecture offers multifold advantages: i) intrinsically high dimensional stability and flame-retardant capability, ii) excellent electrolyte wettability and effective metal dendritic growth inhibition, and iii) powerful physical blockage/chemical anchoring capability for the shuttled polysulfides. As a consequence, the as constructed lithium-sulfur battery using a pure sulfur cathode displays an outstandingly high discharge capacity of 1402.1 mAh g(-1) and a record high cycling stability (approximately average 0.24% capacity decay per cycle within 300 cycles) at 80 degrees C, outperforming the state-of-the-art results in the literature. Promisingly, a high sulfur mass loading of approximate to 3.0 mg cm(-2) and a record low electrolyte/sulfur ratio of 6.0 are achieved. This functional separator also performs well for a high temperature magnesium-sulfur battery. This work demonstrates a new concept for high performance metal-sulfur battery design and promises safe and durable operation of the next generation energy storage systems.