MoS₂ Nanoflakes based Kilohertz Electrochemical Capacitors

An ultra-fast electrochemical capacitor (EC) designed for efficient ripple current smoothing was fabricated using vertically oriented MoS₂ (VOM) nanoflakes deposited on freestanding carbonized cellulose (CC) sheets as electrodes. The daily used cellulose tissue sheets were transformed into electrode scaffolds through a rapid pyrolysis process within a preheated furnace, on which VOM nanoflakes were formed in a conventional hydrothermal process. With these ~10 μm thick VOM-CC electrodes, ultrafast ECs with tunable frequency response and specific capacitance density were fabricated. The ECs with a cell-level areal capacitance density of 0.8 mF/cm² at 120 Hz were demonstrated for ripple current filtering from 60 Hz to 60 kHz. At a lower frequency response level, EC cell with a large capacitance density of 4.8 mF/cm² was also demonstrated. With the facile and easily scaled up process to producing the nanostructured electrode, the miniaturized VOM-CC based ECs have the potential to substitute the bulky aluminum electrolytic capacitors for current smoothing and pulse power applications.