Edge sulfurized graphene nanoplatelets via vacuum mechano-chemical reaction for lithium-sulfur batteries

摘要

Lithium-sulfur batteries have great potential for high energy applications due to their high capacities,low cost and eco-friendliness.However,the particularly rapid capacity decay owing to the dissolution and diffusion of polysulfide intermediate into the electrolyte still hamper their practical applications.And the reported preparation procedures to sulfur based cathode materials are often complex,and hence are rather difficult to produce at large scale.Here,we report a simple mechano-chemical sulfurization methodology in vacuum environment applying bail-milling method combined both the chemical and physical interaction for the one-pot synthesis of edge-sulfurized grapheme nanoplatelets with 3D porous foam structure as cathode materials.The optimal sample of 70％S-GnPs-48 h (ball-milled 48 h) obtains 13.2 wt％ sulfur that chemically bonded onto the edge of GnPs.And the assembled batteries exhibit high initial discharge capacities of 1089 mAh/g at 0.1 C and 950 mAh/g at 0.5 C,and retain a stable discharge capacity of 776 mAh/g after 250 cycles at 0.5 C with a high Coulombic efficiency of over 98％.The excellent performance is mainly attributed to the mechano-chemical interaction between sulfur and grapheme nanoplatelets.This definitely triggers the currently extensive research in lithium-sulfur battery area.