INMA researchers develop a photorechargeable battery that combines solar cells and batteries in a single device
Solar cells and batteries are two well-established technologies in our society, which are considered to play a relevant role in the transition from a fuel-based energy model to a zero-carbon model.
Solar cells allow solar energy to be converted into electrical energy, while batteries convert electrical energy into electrochemical energy and vice versa, allowing energy storage for on-demand use. Given the intermittency of solar energy, the two technologies often work in a complementary way and solar cell and battery packs can be purchased in many household shops. Despite working in complementary ways, the two technologies are optimised to work in different conditions and a single monolithic device that can convert solar energy into electrochemical energy for on-demand use as electrical power has not yet been developed. Such systems would have potential for specific applications where size and weight need to be reduced, as they allow the energy source to be stored and held in a decentralised manner, for example, for use in networks of connected systems for IoT, the internet of things, allowing everything from common household objects such as light bulbs to health care resources, etc., to be connected to the internet, or as energy sources for future microbots and nanobots.
Such systems have been a challenge since the mid-1970s, but it is only in the last few years that research into them has increased dramatically, mainly due to technological advances that require a greater need for portable power.
A group of researchers from the Instituto de Nanociencia y Materiales de Aragón, INMA, a joint centre of the Consejo Superior de Investigaciones Científicas, CSIC and the University of Zaragoza, UNIZAR, formed by Marta Haro Remón (Ramón y Cajal-UNIZAR researcher at INMA) and Emilio J. Juárez-Pérez (ARAID-UNIZAR researcher at INMA) and Isabel Ciria-Ramos, PhD student at INMA, have manufactured a photorechargeable battery, which can be charged up to 87% of its theoretical capacity in 9 hours only when exposed to an LED light without providing external electrical energy.
The system is based on a commercial button-type lithium battery, in which the casing has been adapted to allow the semiconductor material responsible for converting solar energy into electrical energy to be illuminated. A titanium oxide layer is deposited after the semiconductor to store the electrical energy electrochemically. Once photorecharged, the battery can be discharged in the dark, operating like a normal lithium battery. This work has used simple materials such as copper oxide and titanium and has provided new information on the photorecharge mechanism, which will allow further progress to be made in this incipient technology.
This work is part of the national project Photorechargeable Batteries (SoRBat, PID3.29-108247RA-I00) and of the research line initiated by Marta Haro as a Ramón y Cajal researcher (RyC2018-025222I) when she joined the University of Zaragoza at the Institute of Nanoscience and Materials of Aragon.
– Photograph of the work team: From left to right: Isabel Ciria-Ramos Marta Haro and Emilio J. Juárez-Pérez.
– Diagram of the photorechargeable battery.
– Photograph of the photorechargeable lithium button cell battery next to a commercial one.