Fully Printed Thermogalvanic Modules for Low-Grade Energy Harvesting.

Thermogalvanic cells offer a promising route for harvesting low-grade heat by utilizing temperature-dependent redox reactions at spatially separated electrodes. Their potential for low-cost, flexible, and sustainable energy conversion makes them attractive for scalable applications; however, practical implementation is limited by challenges in modular integration and manufacturability. Here, we report the development of a fully printed thermogalvanic module (TGM) that integrates screen-printed hybrid current collectors, activated carbon-based electrodes, an adhesive sealing layer, and a laser-drilled spacer. This fully additive and scalable fabrication strategy enables the precise assembly of complex architectures without traditional stacking or wiring. The resulting 36-cell TGM, employing widely available aqueous electrolytes, demonstrates a reproducible thermopower of 38 mV K and a peak output power of 9 μW under a modest 14 K temperature difference. This work demonstrates a practical pathway toward large-area printed thermogalvanic systems for ambient heat harvesting and paves the way for future integration into flexible and wearable energy platforms.