Abstract:
The performance of supercapacitor degenerates at low temperature, even fails to work sometimes. Solar photothermal conversion provides a new direction for the performance improvement of supercapacitor. Manganese dioxide (MnO
2) has a high specific capacity, while it should be compounded with other active materials due to its low electric conductivity. Therefore, this study aimed to improve the performance of MnO
2-based supercapacitor using the photothermal effect of polypyrrole (PPy), which exhibited excellent light absorption ability and pseudocapacitance property. MnO
2 and PPy were successively deposited on slow filter paper by wet chemistry method and low-temperature interfacial polymerization approach, and PPy/MnO
2 paper-based composites with different PPy contents were prepared. The structures and properties of the composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, cyclic voltammetry, galvanostatic charge/discharge, and AC impedance spectroscopy. The results showed that the porous structure of filter paper was well preserved after PPy deposition, and MnO
2 was covered to form a large active area. The specific capacitance of MnO
2/PPy-400 single electrode reached 1 487.1 mF/cm
2, 67% higher than that of pure PPy electrode. Under the simulated sunlight with the intensity of 1 kW/m
2, the surface temperature of the assembled symmetrical supercapacitor increased from 21.2 °C to 46.7 °C after 10 min. The specific capacitance of the symmetrical supercapacitor assembled by the paper electrode with PPy of 400.0 μL was 52.9 mF/cm
2 with illumination, five times that in dark, suggesting excellent photothermal effect to enhanced capacitor performance.