All electrochemical measurements were carried out in three-electrode system using electrochemical workstation (WonATech Electrochemical Workstation ZIVE SP1) at ambient temperature. The prepared active material ink modified carbon fiber paper was used as working electrodes, an Ag/AgCl electrode with saturated KCl solution was used as reference electrode working with a platinum foil (2.5 cm × 2.5 cm) as counter electrode. 1 M H2SO4 solution was used as electrolyte of the cell. We performed several methods for measurements including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) to study the electrochemical profiles and supercapacitor performance of the fabricated working electrodes. The equations (eqn. 1 to eqn. 6) and detailed calculation are shown in Supplementary note 1. CV was performed from 10 mV/s to 1000 mV/s for VG-M and VG-S, and the capacitive contribution of VG-M was calculated through SI 1 equation 1 . GCD was performed from 1 A/g to 40 A/g for VG-M and VG-S, and the specific capacitance can be obtained from the discharging curves of GCD as SI 1 equation 2 . EIS was performed from 100 kHz to 10 mHz with an amplitude of 5 mV based on a stabilized open circuit potential (OCP). The dielectric relaxation time constant (τ0) can be expressed by SI 1 equation 3 . The real part of complex capacitance and imaginary part of capacitance can be converted from the experimentally obtained impedance results from SI 1 equation 4 -6 .