(Digital) Kilohertz-Frequency Electrochemical Capacitors Based on Vertical MoS₂ Nanoflakes on Carbonized Cellulose Sheets for AC-Line Filtering

Abstract

Electrochemical capacitors (ECs) with kilohertz frequency response were fabricated by the growth of vertically oriented MoS 2 nanoflakes on free-standing carbonized cellulose sheets in a hydrothermal process. The cellulose was carbonized by a rapid pyrolysis process. It was shown that by tuning the MoS 2 deposition time on this carbon scaffold, the frequency range and area-specific capacitance of the device can be easily adjusted. Specifically for AC-line filtering application, an EC cell with a characteristic frequency (i.e., the frequency when the phase angle reaches −45°) of 4kHz was made, which shows a specific capacitance density of 1.6mF/cm 2 and a phase angle of 79.50 at 120Hz. By increasing MoS 2 deposition, EC cells with an areal capacitance of 9.6mF/cm 2 and a characteristic frequency of 580Hz were also fabricated.