High‐Power Hybrid Nanogenerator With Multi‐Degree‐of‐Freedom Mechanical Coupling for Harvesting Water Wave Energy

Wave energy is an important renewable energy source, but its low frequency and irregular amplitude make it difficult to harvest effectively, limiting the application of traditional generators. In this work, we report a high‐power hybrid nanogenerator (HP‐HNG) with multi‐degree‐of‐freedom mechanical coupling, which consists of a transmission system and four power generation modules (PGMs), each comprising an electromagnetic generator (EMG) pumping a main triboelectric nanogenerator (M‐TENG), a rotational electromagnetic generator (R‐EMG), and two rotational triboelectric nanogenerators(R‐TENGs). Water waves can be harvested through the heave and pitch of the HP‐HNG, transforming multi‐degree‐of‐freedom energy input into a single output. Part of the EMG as a charge pump, outputting rectified positive and negative charges into the M‐TENG via voltage‐doubling rectification, achieving ultra‐high surface charge density. The HP‐HNG can reach a peak output power of 0.764 W, corresponding to a peak power density of 127.303 W m − 3 . With a water wave frequency of 1 Hz, the HP‐HNG can charge a 4.7mF capacitor to 2.5 V in 2 s. The HP‐HNG enables real‐time monitoring of submarine cable temperature and displacement through thermometers and other sensors. This work provides a constructive technical pathway for intelligent monitoring of submarine cables, demonstrating strong potential in distributed sensing applications for the marine Internet of Things.