Vertical Graphene Arrays as Electrodes for Ultra-High Energy Density AC Line-Filtering Capacitors

High-frequency responsive electrochemical capacitor (EC), as an ideal lightweight filtering capacitor, can directly convert alternating current (AC) to direct current (DC). However, current electrodes are stuck in limited electrode area and tortuous ion transport. Herein, strictly vertical graphene arrays (SVGAs) prepared by electric-field-assisted plasma enhanced chemical vapour deposition have been successfully designed as the main electrode to ensure ions rapidly adsorb/desorb in richly available graphene surface. SVGAs exhibit an outstanding specific areal capacitance of 1.72 mF cm(-2) at phi(120)=80.6 degrees even after 500 000 cycles, which is far better than that of most carbon-related materials. Impressively, the output voltage could also be improved to 2.5 V when using organic electrolyte. An ultra-high energy density of 0.33 mu Wh cm(-2) can also be handily achieved. Moreover, ECs-SVGAs can well smooth arbitrary AC waveforms into DC signals, exhibiting excellent filtering performance.

Automated summary

The study successfully designed strictly vertical graphene arrays (SVGAs) as the main electrode for the capacitor, showing excellent specific areal capacitance and cycle life. Using organic electrolyte can further increase the output voltage, achieving ultra-high energy density. ECs-SVGAs can effectively smooth arbitrary AC waveforms into DC signals, exhibiting outstanding filtering performance.