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

Abstract 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 NaV ₃ O ₈ (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 (Al ³⁺ 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 Al ³⁺ 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.