Gravity-Induced Self-Charging in Carbon Nanotube/Polymer Supercapacitors

As a distinctive type of energy devices, supercapacitors have received great attention because of their practical applications in recent years. In this work, a self-charging phenomenon induced by gravity is reported in paper-like supercapacitors, which consisted of two polyaniline/carbon nanotube composite (PANI/CNT) electrodes and a polyvinyl alcohol/H2SO4 (PVA/H2SO4) gel electrolyte. Without external electric power supply, the PANI/CNT supercapacitors could provide a maximal output voltage of 0.15 V in ambient environment (24 °C, relative humidity about 60%). Concentration gradient-induced potential difference was excluded for our experiments. Our investigation reveals that the self-charging phenomenon in these supercapacitors can be explained by the gravity-induced streaming potential. As this phenomenon has not been reported before, we hope it could provide new ideas for self-charging energy storage devices.