New photo-assisted charging supercapacitors using WS2-polyaniline photoelectrodes produced by the electropolymerization method

Photo-powered supercapacitors (PPSCs) are regarded as innovative energy storage solutions that efficiently convert solar energy into electrical energy. We develop PPSCs with WS₂-polyaniline composite electrodes (WSPA), prepared by electro-polymerization, and these exhibit excellent photoelectrochemical properties. The electrochemical properties of the electrodes depend on the electro-polymerization cycles. The WSPA-150c photoelectrode achieves a specific capacitance of 6.339 F/g at 0.03 A/g in 6.0 M LiCl under illumination, a 126.9 % increase over dark conditions. Symmetrical and asymmetrical PPSCs with WSPA@FTO electrodes are assembled, enabling direct charging with light without an external power supply. The symmetrical WSPA@FTO||WSPA@FTO device delivers 0.48 mF/cm² at 0.03 mA/cm² in the dark (1.5 F/g), and 0.83 mF/cm² under illumination, which is 1.73 times higher than its performance in the dark. It has an energy density of 0.27 mWh/cm² (0.83 Wh/g), a power density of 12.15 mW/cm² (37.35 W/g) and retains 97.74 % of its original capacity after 10,000 cycles. An asymmetric PPSC with WSPA@FTO as the positive electrode and graphite foil as the negative electrode reaches 1.29 mF/cm² in the light (65.4 % higher than 0.78 mF/cm² in the dark at the same current density). After 10,000 cycles, the device not only retains its capacity but also shows an increase of 30 %.