In situ reduction of WS2 nanosheets for WS2/reduced graphene oxide composite with superior Li-ion storage

Abstract

Two-dimensional transition-metal dichalcogenides, such as tungsten disulfide (WS2), have been actively studied as suitable candidates for anode materials used in lithium ion batteries recently, due to their remarkable ion intercalation properties. However, the difficulties in the synthesis of phase-pure WS2, restacking between WS2 nanosheets, low electronic conductivity and brittle nature of WS2 severely limit its Li-ion batteries application. Here, we adopt a one-pot method for synthesizing of WS2/reduced Graphene Oxide (rGO) composite to improve the battery performance dramatically. The WS2/rGO anode shows a stable discharge capacity of 431.2 mAh/g, at a current density of 0.1 A/g after 100 cycles, while the capacity of bare WS2 is only 65.5 mAh/g under the same condition. The added graphene oxide is reduced to rGO in reaction process and constitute stable composite with WS2, not only avoiding the restacking between WS2 nanosheets and improving the conductive properties, but also promoting the reduction of WO3 effectively. Our work may provide a possible route to avoid oxygen impurities in transition metal dichalcogenides.