Fig. 6. Electrochemical characterization of HSCs. (a) CV obtained for GR/VN NSP and GR/V₂O₅ NSP at a sweep rate of 5 mV s⁻¹ in a three-electrode system. (b) CV curves of HSCs measured at operating voltages over 1.6 V at a constant sweep rate of 15 mV s⁻¹. (c) Galvanostatic charge–discharge curves of the HSCs device collected over different voltages from 0.8 to 1.6 V at a current density of 1 A g⁻¹. (d) Specific capacitance and energy density calculated based on galvanostatic charge–discharge curves obtained at 1 A g⁻¹ as a function of the potential window.