New Supercapacitor Charged by Light
Researchers have developed a groundbreaking supercapacitor that can be charged by exposure to light, presenting exciting possibilities for self-powered electronics such as sensors and streetlights. Unlike traditional capacitors that store energy electrostatically, supercapacitors store significantly more energy by exploiting electrochemical properties. The new design is a significant leap in energy storage technology.
The team made the supercapacitor’s electrodes from Zinc Oxide (ZnO) nanorods grown on a transparent fluorine-doped tin oxide (FTO) substrate. ZnO and FTO are semiconductors whose energy levels are precisely aligned to enable superior charge storage performance. The transparent FTO allows light to reach the ZnO nanorods, charging the supercapacitor. The device achieves higher energy storage efficiency by combining a liquid and semi-solid gel electrolyte between the electrodes.
The supercapacitor exhibited a considerable increase in capacitance when exposed to ultraviolet (UV) light, surpassing previously reported designs. Uniquely, its capacitance increased with rising voltage under light, contrary to typical behavior, a phenomenon the researchers dubbed “necking behavior.” They believe the porous nature of the electrodes contributes to this effect. Furthermore, the team discovered that the energy stored in the supercapacitor increased when charged quickly under UV light, which is atypical, as fast charging generally reduces energy storage due to ion movement limitations in electrolytes.
These observations suggest that the team’s supercapacitor design could lead to fast-charging, energy-dense devices. The researchers optimized the supercapacitor’s performance by increasing the surface area of the electrodes and using a liquid electrolyte to form an effective electric double layer (EDL), resulting in superior charge generation and storage.
The potential applications for this light-charged supercapacitor are extensive. With high power density, the supercapacitor could replace solar cells in streetlights, as it releases charge faster than traditional batteries. It also holds promise for powering microelectronic chips in portable devices like cell phones.
Looking ahead, the IISc-Clemson team plans to continue refining the design to charge the supercapacitor with visible and infrared light, further expanding its applicability. Their research represents a significant advancement in supercapacitor technology, paving the way for faster-charging, more efficient energy storage devices in various electronic applications.
