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

With one of these on your next wearable, as little as 30 seconds of sunlight could keep your device topped up.

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.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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