High-Performance Wearable Joule Heater Derived from Sea–Island Microfiber Nonwoven Fabric

A three-dimensional (3D) hierarchical microfiber bundle-based scaffold integrated with silver nanowires (AgNWs) and porous polyurethane (PU) was designed for the Joule heater via a facile dip-coating method. The interconnected micrometer-sized voids and unique hierarchical structure benefit uniform AgNWs anchored and the formation of a high-efficiency 3D conductive network. As expected, this composite exhibits a superior electrical conductivity of 1586.4 S/m and the best electrothermal conversion performance of 118.6 °C at 2.0 V compared to reported wearable Joule heaters to date. Moreover, the durable microfiber bundle–PU network provides strong mechanical properties, allowing for the stable and durable electrothermal performance of such a composite to resist twisting, bending, abrasion, and washing. Application studies show that this kind of Joule heater is suitable for a wide range of applications, such as seat heating, a heating jacket, personal thermal management, etc.