Milliwatt-Scale Moisture-Induced Power Generation via Cation Intercalation in Sodium Vanadium Oxide Nanobelts.

A moisture-induced power generator (MPG) with exceptionally high-power output and extended operational stability is developed by systematically integrating three active materials: A LiCl -containing hydrogel, a perforated aluminum sheet, and NaV3O8 (NVO) nanobelts. The LiCl-containing hydrogel, due to its hygroscopic nature, maintains a stable moisture gradient and supplies charge carriers (Li+ ions). Simultaneously, the perforated aluminum sheet acts as the primary source of charge carriers (Al3+ ions) without generating oppositely charged ions, thereby preventing the degradation of the potential difference caused by ion migration. The NVO nanobelts undergo a reduction reaction through the intercalation of Li+ and Al3+ ions into their layered structure, effectively preventing reverse migration by resolving charge accumulation and generating Faradaic currents. Furthermore, their elongated structure enables the formation of a high-surface, conductive active layer through entanglement with carbon black nanoparticles, eliminating the need for binder materials. This systematic design achieves a maximum open-circuit voltage of 1.64 V, a short-circuit current of 10.44 mA cm-2, and a power density of 2.13 mW cm-2 at a load resistance of 200 Ω under 90% relative humidity. These results represent a record-high performance among reported MPGs, highlighting significant advancements in efficiency and durability, thereby enhancing the feasibility of MPGs for practical applications.