Correlating mass loading to electrochemical performance of activated carbon electrode

The commercialization of any energy storage technologies requires the development of high mass loading electrode, including that for supercapacitors. However, different from the faradaic bulk reaction in lithium-ion batteries, supercapacitors adopted non-faradaic surface charge accumulation mechanism during charge storage. Under such circumstance, high mass loading cannot be directly related to higher energy density for supercapacitor. Here, the effect of mass loading on the electrochemical performance and storage efficiency of the activated carbon symmetry supercapacitor was investigated. The achievable capacitance increases with mass loading at identical current density, from 60.9 mF in 1.8 mg/cm2 to 624.6 mF in 21.2 mg/cm2. However, the specific capacitance and energy density decreased from 33.4 F/g in 1.8 mg/cm2 to 29.5 F/g in 21.2 mg/cm2, attributable to the increase in dead weight from the bulk of the electrode. The results presented here concluded that increasing the capacitance of aqueous electrolyte-based supercapacitor through high mass loading does not contributes positively to the energy density, while widening the working voltage would be a better alternative.