A Flexible Thermoelectric Generator with Optimized Design for Low-Thermal Heat Waste Energy Harvesting

The growing need for eco-friendly energy alternatives has driven the investigation into thermoelectric generators (TEGs), which have the ability to convert thermal energy into electricity. This study concentrates on the advancement of a flexible thermoelectric generator (FTEG) that is designed with an enhanced structure to optimize the capture of heat energy from domestic electrical appliances and human warmth. By incorporating a polyimide (PI) film base and a flexible, high thermal conductivity silica-AlN composite layer for improved heat dissipation on the cooler side, the FTEG demonstrates remarkable flexibility and efficiency in capturing body waste heat under vertical temperature gradients, which can be utilized to power portable electronic devices. Additionally, silica aerogel is used between the thermoelectric legs to improve thermal insulation, ensuring that heat can effectively pass through the thermoelectric legs. The performance assessment of the FTEG shows promising results. At ambient temperature (23 °C), the FTEG generates an open-circuit voltage of 35 mV and a peak power output of 110.2 μW by harnessing human body heat. Furthermore, with a temperature gradient of 50 K, the FTEG produces an open-circuit voltage of 173 mV, a power output of 4.5 mW, and a power density of 127 μW/cm2 under a 2 Ω load resistance. The FTEG also showcases its adaptability by efficiently converting waste heat from the human body into electricity that can power electronic watches and LED lights after voltage enhancement with a DC booster. In addition, this research introduces a state-of-charge (SOC) prediction method for tracking the battery charging process, indicating the feasibility of integrating human body energy harvesting with sophisticated energy management systems.