Supramolecular-Assembled Nanoporous Film with Switchable Metal Salts for a Triboelectric Nanogenerator

A triboelectric nanogenerators (TENG) are of great interest as emerging power harvesters because of their simple device architecture with unprecedented high efficiency. Despite the substantial development of new constituent materials and device architectures, a TENG with a switchable surface on a single device, which allows for facile control of the triboelectric output performance, remains a challenge. Here, a supramolecular route for fabricating a novel TENG based on an alkali-metal-bound porous film, where the alkali metal ions are readily switched among one another is demonstrated. The soft nanoporous TENG contains numerous SO₃ ⁻ groups on the surface of nanopores prepared from the supramolecular assembly of sulfonic-acid-terminated polystyrene and poly(2-vinylpyridine) (P2VP), followed by soft etching of P2VP. Selective binding of alkali metal ions, including Li⁺, Na⁺, K⁺, and Cs⁺, with SO₃ ⁻ groups enables the development of mechanically robust alkali-metal-ion-decorated TENGs. The triboelectric output performance of the devices strongly depends on the alkali metal ion species, and the output power ranges from 11.5 to 256.5 µW. This wide-range triboelectric tuning can be achieved simply by a conventional ion exchange process in a reversible manner, thereby allowing reversible control of the output performance in a single device platform.