Humidity-Resistant Triboelectric Nanogenerators Enabled by Hofmeister Salting-Out Effect in Quaternized Block Copolymer Films

Triboelectric nanogenerators (TENGs) have emerged as a promising technology for harvesting ambient mechanical energy. However, their practical applications are severely limited in high-humidity environments, where continuous moisture adsorption onto the dielectric surface accelerates water-induced charge dissipation, resulting in a dramatic loss of output performance.

To overcome this long-standing limitation, we report a robust, humidity-resistant TENG utilizing ion-exchanged self-assembled block copolymer thin films. We fabricated well-ordered lamellar nanostructures using poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) block copolymers, followed by the ionic quaternization of the P2VP domains with iodine. Crucially, the initial iodide anions were systematically exchanged with various counterions along the Hofmeister series to modulate the moisture affinity and charge retention of the electret surface.

Remarkably, by optimizing the counterion species based on the Hofmeister series, the engineered TENG exhibited exceptional electrical output stability even under extreme humidity conditions exceeding 95% RH (with severe fogging), where conventional TENGs completely failed. This unprecedented performance is attributed to the strong salting-out effect driven by the selected counterions within the lamellar domains, which efficiently suppresses moisture-induced charge screening and layout dissipation. This study introduces a facile and precise ion-engineering strategy based on the Hofmeister series to design moisture-resilient polymer electrets, opening up new avenues for real-world all-weather energy harvesting systems.