  A novel WS2-graphite dual-ion battery (DIB) is developed by combining
together a conventional graphite cathode and high-capacity few-layer WS2 flakes
anode. The WS2 flakes are produced by exploiting wet-jet milling (WJM)
exfoliation, which allows mass production of few-layer WS2 flakes in
dispersion, with an exfoliation yield of 100%. The WS2-anodes enable DIBs,
based on hexafluorophosphate (PF6-) and lithium (Li+) ions, to achieve charge
specific capacities of 457, 438, 421, 403, 295 and 169 mAh g-1 at current rates
of 0.1, 0.2, 0.3, 0.4, 0.8 and 1.0 A g-1, respectively, outperforming
conventional DIBs. The WS2-based DIBs operate in the 0 to 4 V cell voltage
range, thus extending the operating voltage window of conventional WS2-based
Li-ion batteries (LIBs). These results demonstrate a new route towards the
exploitation of WS2, and possibly other transition metal dichalcogenides
(TMDs), for the development of next-generation energy storage devices.
