Combined Battery and Solar Cell Can Drive Wearables for Tens of Minutes After Just 30s of Sunlight

A team of scientists from the Universities of Surrey and Cyprus, Zhengzhou University, and the National Physical Laboratory in Middlesex have come up with a prototype battery that, they claim, could keep wearable devices topped up with just "seconds" of exposure to sunlight.

"This technology provides a promising strategy for efficient use of clean energy and enables wearable electronics to be operated continuously without plug-in charging," claims first author Jinxin Bi of the work. "Our prototype could represent a step forward to how we interact with wearables and other internet-of-things devices, such as remote real-time health monitors."

The device in question: A combined zinc micro-battery and perovskite solar cell, built using inkjet printing and electrodeposition, which can be integrated into wearable electronics to harvest energy from sunlight with a high efficiency — high enough, the team found during experimental testing of the prototype, to power functional electronics like LEDs and a pressure sensor for tens of minutes with just 30 seconds of light exposure.

"The unique features in our ultrafast photo-rechargeable system could promote wide applications in self-powered wearable Internet of Things [IoT], autonomous power systems, and emergency electronics," says Yunglong Zhao, PhD and project co-lead. "In addition, it will broaden the perception and insight of designing the next generation of miniaturized flexible photo-rechargeable systems."

The prototype offers a volumetric energy density of 148 mWh cm⁻³ and a power density of 55 W cm⁻², comparable to existing state-of-the-art micro-battery and supercapacitor energy storage systems — but with the benefit of the integrated solar cell, allowing for energy harvesting without external components.

The team's work has been published in the journal Energy Storage Materials under open-access terms.