LAUSR

Motivated by the presence of metallic conductivity in the group VI transition metal dichalcogenides, the supercapacitive performance of the 1T phase of molybdenum (MoS2xSe2(1–x)) sulfoselenides is explored. Ultrahigh frequency response (∼1.4 kHz) along with excellent electrochemical stability are exhibited by 1T MoS2xSe2(1–x)-based supercapacitors. The S:Se ratio in the mixed chalcogenide is shown to influence the rate performance of the device. High areal capacitances of ∼450 μF cm–2 with short RC time constants of ∼1.3–3.2 ms at 120 Hz are achieved in the case of 1T MoSSe phase. The i–v characteristics are almost rectangular at very high scan rates of ∼1000 V s–1. Very stable gravimetric specific capacitance of ∼36 F g–1 is retained for several thousands of charge–discharge cycles leading to an energy density of ∼12.1 Wh kg–1 at a specific power of ∼842 W kg–1. The observed specific power of ∼50 kW kg–1 at ∼1.5 Wh kg–1 energy density makes the sulfoselenide phase capacitors attractive for high power app...