Development prospects of metal-based two-dimensional nanomaterials in lithium-sulfur batteries

A lithium-sulfur (Li-S) system is an important candidate for future lithium-ion system due to its low cost and high specific theoretical capacity (1675 mAh/g, 2600 Wh/kg), which is greatly hindered by the poor conductivity of sulfur, large volume change and dissolution of lithium polysulfides. Two-dimensional (2D) materials with monolayers or few-layers usually have peculiar structures and physical/chemical properties, which can resolve the critical issues in Li-S batteries. Especially, the metal-based 2D nanomaterials, including ferrum, cobalt or other metal-based composites with various anions, can provide high conductivity, large surface area and abundant reaction sites for restraining the diffusion for lithium polysulfides. In this mini-review, we will present an overview of recent developments on metal-based 2D nanomaterials with various anions as the electrode materials for Li-S batteries. Since the main bottleneck for the Li-S system is the shuttle of polysulfides, emphasis is placed on the structure and components, physical/chemical interaction and interaction mechanisms of the 2D materials. Finally, the challenges and prospects of metal-based 2D nanomaterials for Li-S batteries are discussed and proposed.