image: Researchers have developed a novel method to transform commercially available warm pastes into functional iron-air batteries for emergency power generation. The technology redirects the chemical energy that would normally produce heat (reaching temperatures up to 41°C as shown in thermal imaging) into electrical energy instead. The conversion process involves reconfiguring the warm paste's iron-based materials by adding hydrogel layers and catalysts to create electrochemical reactions (Cathode: O2 + 2H2O + 4e− → 4OH−; Anode: Fe + 3OH− → FeOOH + H2O + 3e−). This innovative approach repurposes the same chemical energy source - transforming heat-generating warm pastes into electricity-producing batteries through a simple assembly process involving non-woven powder backing layers and catalyst components. Scheme 1. Conversion of a warm paste into an emergency power source. The left panel shows the temperature profile, internal structure, and an infrared thermal image illustrating the temperature distribution during operation. The right panel illustrates the step-by-step assembly process of the iron–air battery.
Credit: ©Science China Press
Outdoor adventurers and emergency responders now have a potentially life-saving new power option thanks to researchers at Nanjing University who have developed a way to convert common warm paste into emergency batteries.
The research team, led by Professor Ping He, created a hydrogel-based iron-air battery system that can be rapidly assembled using readily available warm paste materials. These heating pads, commonly used to provide warmth in cold conditions, contain iron powder that undergoes an oxidation reaction to generate heat.
"We realized that the same chemical reaction that produces heat in warm pastes could be harnessed to generate electrical power instead," said Professor He. "By designing the right battery architecture with a hydrogel electrolyte, we can convert this thermal energy source into a portable emergency power supply." The key innovation lies in the modified hydrogel electrolyte, which contains 3% polyacrylic acid potassium salt (PAAK) and 0.5% sodium lignosulfonate. This electrolyte maintains high ionic conductivity even at extremely low temperatures, with a freezing point of -53°C, and prevents battery leakage while effectively binding the iron powder anode. Performance tests showed impressive results: the battery generates 0.98V voltage and delivers 2.68 Ah capacity at room temperature. Even at -20°C, the system maintains functionality with 1.24 Ah capacity. When four cells are connected in series, they provide sufficient power to charge a mobile phone, ensuring critical communication capabilities during emergencies.
The researchers demonstrated the practical application by powering LED lights and successfully charging smartphones, even in sub-zero conditions. The assembled battery achieved an energy density of 89.92 Wh kg−1, comparing favorably to commercial lead-acid batteries. This breakthrough offers significant advantages for outdoor activities and emergency situations where both warmth and power are crucial for survival. The battery can be manually assembled using the original warm paste packaging, requiring no specialized equipment or complex procedures.