Unraveling the detrimental crosstalk between cathode and anode in the aqueous asymmetric capacitor of activated carbon /copper oxide

While the study on the aqueous asymmetric capacitor of activated carbon/copper oxide has reached a relatively mature stage, further progress in the technology relies on overcoming specific issues. This paper proposes and eliminates a detrimental crosstalk between the CuO cathode and AC anode , which impairs the cyclic performance of capacitor. During the charging process, Cu 2+ dissolves from the CuO cathode and deposits as Cu/Cu 2 O crystals on the surface of AC anode. These deposits obstruct the pores of activated carbon and then diminish the specific surface area of the electric double layer , consequently decreasing capacitance performance of capacitors. The capacitors demonstrate a remarkable enhancement in cycle life by adding an anion exchange membrane between two electrodes to shut off this crosstalk. After 10,000 cycles at 1 A g −1 , the capacity retention rate of AC/CuO capacitors is increased by 36.6 %, reaching 94.1 %. Even at higher current densities , the capacitors maintain superior cyclic stability. This study is a significant stride in aqueous asymmetric capacitors.