Ultrafast electrochemical capacitors running at frequencies in the range of hundreds or even kilo hertz have attracted considerable interest for AC-line filtering, pulse power generation and other applications. The electrode structure design, by facilitating electron conduction in the electrode itself and electrolytic ion transportation in the pores of electrode material, as well as providing an easily accessible large surface area, plays key roles in determining the frequency response and achievable capacitance of the electrochemical capacitor. Herein, we present studies of edge-dominated graphene cluster wrapped metal nanoparticles for design of ultrafast electrochemical capacitors. CoNi nanoparticles were loaded on cellulose fiber sheets, which were treated in CH₄/H₂ plasma for a few minutes. The high temperature plasma pyrolyzed cellulose fiber sheets into carbon fibers as freestanding electrodes, while high-density edge-oriented graphene flakes wrapped around metal nanoparticles to intimately bond with carbon fibers for a minimized electrode resistance. The densely packed and edge-oriented graphene clusters offer a large but easily accessible surface area. Such an electrode showed enhanced areal capacitance of 0.9 mF and ultrafast frequency response with a phase angle of -82.5^o at 120 Hz. Electrode fabrication, nanostructure characterization, electrochemical studies and preliminary device applications will be presented.