Fully Food-Packaging-Derived Contact-Separation TENG via a Solvent-Free Route for Low-Frequency Energy Harvesting

Waste food packaging with a unique polymer-Al-polymer multilayer structure serves as an ideal raw material for constructing triboelectric nanogenerators (TENGs). This work proposes a fully food-packaging-derived contact-separation TENG (FPD-TENG) for low-frequency mechanical energy harvesting, where the PET tribo-layer uses the pristine packaging film and the Al electrode is exposed via a facile solvent-free strategy. The solvent-free method only requires treating the multilayer packaging in boiling water for 2 min to peel off the outer PET film and expose the internal Al electrode, which thoroughly eliminates the use of chemical reagents and avoids secondary environmental pollution. To enhance the electrical output performance of the pristine FPD-TENG, a three-stage voltage-multiplying circuit (VMC) is integrated, boosting the charge density from 0.055 mC m^-2 to 0.26 mC m^-2 (a 4.7-fold improvement). Furthermore, an energy management circuit (EMC) is integrated to improve the energy utilization of the TENG system. The EMC increases the capacitor charging rate by more than 2.5 times. In the tested setup, a small electronic clock is continuously powered by the device for 10 min and operates normally. Overall, this work demonstrates that waste multilayer food packaging can be repurposed as high-efficiency, low-frequency energy harvesters through a facile and solvent-free recycling strategy, providing a green and feasible route for the high-value utilization of packaging waste.