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

Abstract

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% (∼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.