The use of graphene and its composites to suppress the shuttle effect in lithium-sulfur batteries

Abstract

The lithium sulfur battery has a high theoretical capacity of 1675 mAh g−1, and is cheap and environmentally friendly, which make it a very promising secondary battery. However, its cycling stability cannot meet the requirements of industrialization due to the shuttle effect caused by the dissolution of polysulfides in the discharge process, the insulating nature of sulfur and the volume expansion of the sulfur cathode. Graphene has an excellent electrical conductivity, an extremely large specific surface area, good mechanical flexibility, and thermal and chemical stability, making it and its derivatives promising candidates to modify both the electrodes of an all-solid-state lithium-sulfur battery and the separator. The mechanisms, by which graphene and its derivatives inhibit the shuttle effect are summarized. The graphene network is very favorable for improving electron transfer rate, limiting volume expansion and facilitating lithium ion migration in the sulfur cathode of all-solid-state lithium-sulfur batteries. As modifiers of the separator, the hexagonal layer structure of graphene and its derivatives forms channels for lithium-ion transport and sulfur capture. Development strategies for using graphene and its derivatives in lithium-sulfur batteries are proposed.