Researchers from North Carolina State University and Rice University have created a nontoxic, stretchable battery that operates by extracting moisture from the ambient environment—even in climates as dry as the desert. The batteries could be useful in Internet of Things (IoT) applications ranging from wearables to advanced surveillance monitors with built-in kill switches. The study is published in the journal Science Advances.

Emerging technologies like wearable monitors, miniature robotics and other IoT devices require lightweight, flexible power sources. Conventional batteries, which represent the best power source options, are often too rigid and heavy to be useful, and they contain toxic materials that can leak. Energy harvesters, so called because they capture energy from the surrounding environment and convert it into electrical power, are lighter, but their performance is limited.

Running on moisture and salt The new moisture-activated battery (MAB) includes a magnesium anode and a silver/silver chloride cathode, with a cellulose membrane loaded with lithium chloride salts that serves as a separator. The separator harvests moisture from ambient air, which dissolves the salts and creates the electrolyte, allowing charge to flow through the battery.