A novel aqueous-based asymmetrical-bipolar electrochemical capacitor (EC) was developed. The EC device has leveraged the contributions from a Zn-CNT asymmetrical electrode and a KOH-H2SO4 dual-pH electrolyte. The positive and the negative electrodes operate in their respective electrolytes that have different pH values, leading to a cell voltage of 2.4 V. The potential tracking of both electrodes reveals that the Zn negative electrode maintains a potential of -1.2 V, while the CNT positive electrode is charged and discharged reversible up to +1.2 V. A bipolar ion exchange membrane effectively separates the acid and the alkaline from neutralizing. As a result, the aqueous-based asymmetrical-bipolar EC device has shown stable performance with a capacitance retention of 94 % and a coulombic efficiency of 99% over 10,000 cycles. The asymmetrical-bipolar design overcomes the thermodynamic limitation of water decomposition of the aqueous-based electrolyte, paving a new avenue towards aqueous-based ECs and energy storage systems with both high energy and power density.