Integrating a redox-coupled FeSe2/N-C photoelectrode into potassium ion hybrid capacitors for photoassisted charging

With a high-energy density and high-power output, potassium ion hybrid capacitors (PIHCs) are promising next-generation energy storage devices. However, the poor K+ electrochemical performance of battery-type anodes remains a challenge due to the inherent insulating property and the poor ion-transport kinetic of the anode materials. Herein, we report an integrated photoelectrode to achieve significantly enhanced K+ storage performance. The electron-hole pairs generated by the integrated photoelectrode under light-irradiation synergistically enhance the electrochemical adsorption of K+ and reversible ion-transport kinetics. Specifically, in the presence of Z907 dye that matches the energy level of the FeSe2 integrated anode, the reaction energy barrier during illumination was significantly reduced by 35.7% (similar to 0.05 eV). A remarkable increase in capacitance is therefore achieved to 23.8% at 3 A g(-1) (under light). This discovery provides an effective pathway for breaking the energy density of PHIC only by the conversion and storage of solar energy.