WS2 Nanowires as a High-Performance Anode for Sodium-Ion Batteries.

ABSTRACT

We report the synthesis and anode application for sodium-ion batteries (SIBs) of WS2 nanowires (WS2 NWs). WS2 NWs with very thin diameter of ≈25 nm and expanded interlayer spacing of 0.83 nm were prepared by using a facile solvothermal method followed by a heat treatment. The as-prepared WS2 NWs were evaluated as anode materials of SIBs in two potential windows of 0.01-2.5 V and 0.5-3 V. WS2 NWs displayed a remarkable capacity (605.3 mA h g(-1) at 100 mA g(-1) ) but with irreversible conversion reaction in the potential window of 0.01-2.5 V. In comparison, WS2 NWs showed a reversible intercalation mechanism in the potential window of 0.5-3 V, in which the nanowire-framework is well maintained. In the latter case, the interlayers of WS2 are gradually expanded and exfoliated during repeated charge-discharge cycling. This not only provides more active sites and open channels for the intercalation of Na(+) but also facilitates the electronic and ionic diffusion. Therefore, WS2 NWs exhibited an ultra-long cycle life with high capacity and rate capability in the potential window of 0.5-3 V. This study shows that WS2 NWs are promising as the anode materials of room-temperature SIBs.