China's new iron-air battery can power phones, LEDs even in -63°F

Researchers at the University of Nanjing in China have developed an innovative iron-air battery that can be quickly assembled from common warm pastes typically used in heating pads. These pads contain iron powder that oxidizes to generate heat, and the research team, led by Professor Ping He, repurposed this chemical reaction to produce electricity instead. By combining the iron powder with a specially formulated hydrogel electrolyte—containing polyacrylic acid potassium salt and sodium lignosulfonate—the battery achieves enhanced stability and performance, even in extreme cold conditions down to -63.4°F (-53°C). The battery demonstrated practical capabilities, producing 0.98 volts and 2.68 ampere-hours at room temperature, and maintaining 1.24 ampere-hours at -4°F (-20°C). When four cells were connected in series, the system could charge a smartphone and power LED lights, with an energy density comparable to some commercial lead-acid batteries but using safer, more accessible materials.