Performance enhancement of a graphene–sulfur composite as a lithium–sulfur battery electrode by coating with an ultrathin Al2O3 film via atomic layer deposition

Abstract

A graphene–sulfur (G–S) composite was conformally coated with an ultrathin Al₂O₃ film via atomic layer deposition (ALD) and used as the cathode of a lithium–sulfur (Li–S) battery. The G–S composite cathode with an ALD-Al₂O₃ coating delivered a high specific capacity of 646 mA h g⁻¹ after 100 charge–discharge cycles at 0.5 C, and this value is about twice that of the bare G–S composite. The rate capability and coulombic efficiency of the G–S composite electrode were also greatly increased. The ALD-Al₂O₃ coating worked as an artificial barrier to suppress the dissolution of polysulfides and alleviate the shuttle effect; thus, it effectively improved the performance of a G–S composite cathode in a Li–S battery.