Coupling Triboelectric and Thermomagnetic Effects as a Novel Low-Grade Thermal Energy Harvesting Technology

Energy has been one of the major driving forces behind our societal development and economic growth. However, the resulting surge in energy demand has also led to the major environmental crisis we now face. Thus, new energy generation technologies able to convert low-grade thermal energy into electricity are urgent to tackle the continuous surge in energy demand. Here, a hybrid device that couples triboelectric and thermomagnetic effects to generate electrical power in the presence of small temperature gradients near room temperature was demonstrated [1]. Triboelectric nanogenerators (TENGs), appearing just in 2012 [2], are already one of the most promising mechanical energy harvesting technologies [3-5]. In this work, the thermomagnetic effect allowed us to induce the periodic and sustained motion of a second-order ferromagnetic material in temperature gradients below 30 °C. This mechanical motion was converted into electrical energy using a TENG. The applicability of this concept was demonstrated in a broad range of operating temperatures in both the cold (15 to 37 °C) and hot (60 to 90 °C) sides. Varying the temperature gradients with TENG assembled in the cold-side, a maximum power density of 18 mWm⁻² was reached using a cold- and hot-sides temperature of 30 and 65 °C. When assembled in the hot-side, the TENG generated a maximum power density of 54.7 mWm⁻² for cold- and hot-side temperature of ~20 and 65 °C. It was further shown that the electrical power generated by the hybrid TENG is more than 35× higher than that obtained by a conventional thermomagnetic generator. This work showed that TENGs is a high-efficient harvesting technology to use the temperature difference and vibration mechanical energy as electrical energy sources.<br/><br/><b>References:</b><br/>1. C. Rodrigues et al., Advanced Functional Materials,32 (2022)<br/>2. F-R. Fan et al, Nano Letters, 12 (2012).<br/>3. C. Wu et al., Advanced Energy Materials, 9 (2019).<br/>4. C. Rodrigues et al., Energy and Environmental Science,13 (2020).<br/>5. C. Rodrigues et al., Nano Energy, 72 (2020)