Performance enhanced triboelectric nanogenerator by taking advantage of water in humid environments

Highlights: ●A high performance HR-TENG that can work stably in high humidity environment was developed. ●The output charge density (244 μC/m²) higher than the reported value 110 μC/m² of HR-TENG was achieved in high RH condition. ●A self-powered human respiratory monitoring sensor in high RH conditions was demonstrated. Improving the performance of triboelectric nanogenerator (TENG) in environment with high humidity is critical for their applications in blue energy, humidity sensing, implantable nanodevice etc. Here, we report a kind of humidity-resisting TENG (HR-TENG) by using polyvinyl alcohol/lithium chloride (PVA/LiCl) as the triboelectric layer, the output of which is much enhanced (~5 times) with the increase of relative humidity (RH, from 20% to 99%). Abundant hydroxyl groups in PVA can fix water molecules to form more tribo-positive surface polarity, and LiCl can regulate the water absorption ability of PVA/LiCl film. The combined effect brings in numbers of wrinkle microstructure on its surface and synchronously decreases its modulus, enabling more efficient contact. Charge density of the HR-TENGs are higher than 115 μC/m² in a wide range of RH (from 60% to 99%), especially, reaches a maximum value of 244 μC/m² in 90% RH, which is much larger than the highest value 110 μC/m² among reported HR-TENGs (RH>50%). Moreover, the PVA/LiCl based TENGs can be acted as power source in high RH (93%) condition and respiratory monitoring sensor for human physiological monitoring. These results provide an efficient way for TENG with high output in high humidity environments.