To further confirm the possible Zn 2+ and H + co-insertion three electrode cyclic voltammetry (CV) measurements with Pt counter electrode and Ag/AgCl reference electrode were performed using different aqueous electrolytes including 3 M ZnSO4 with a measured pH=3.7, 3 M ZnSO4 + H2SO4 (pH = 1), H2SO4 (pH = 3.7), H2SO4 (pH = 1), and 0.1 M ZnSO4 + H2SO4 (pH = 1) (Figure , Figure ). Cyclic voltammetry in 3 M ZnSO4 revealed several peaks (Figure , red), which roughly match the peaks obtained from galvanostatic cycling in the Zn-OTQC battery (Figure ). H2SO4 pH = 3.7 electrolyte was used to simulate the H + activity without the interference of Zn 2+ ions. The activity of H + proved to be insufficient for significant electroactivity (Figure ), therefore, more concentrated H2SO4 pH = 1 was used. Cyclic voltammogram in more concentrated H2SO4 showed electroactivity comparable with 3 M ZnSO4, which proves the possibility of H + insertion into the OTQC (Figure , green).