Readily recyclable, degradable, stretchable, highly conductive, anti-freezing and anti-drying glycerohydrogel for triboelectric nanogenerator

Hydrogel-based triboelectric nanogenerators (TENGs) have been widely investigated because of their biomimetic mechanical properties. However, most existing hydrogels exhibit limited tolerance to low-temperature and arid conditions. Moreover, they generally lack degradability and recyclability, and even those with recyclability often require harsh conditions such as organic solvents or high temperatures, limiting their further development. Here, we develop gelatin glycerohydrogels to simultaneously address the above obstacles. The multiple physical interactions notably simplify the recycling procedure, expedite the recycling process, and endows the gel with excellent recyclability and degradability, while the strong hydrogen bond between the glycerol and water molecules significantly enhances the anti-freezing (−80 °C) and anti-drying properties of the gel. In addition, its conductivity is relatively high (1.65 S/m) among reported recyclable ionic conductive hydrogels. Subsequently, a glycerohydrogel-based triboelectric nanogenerator (G-TENG) is developed, exhibiting high electrical output (power density reached 0.44 W/m²), good durability (>3000 times) and maintaining nearly consistent performances after recycling. Moreover, G-TENG retains functionality in both dry and freezing environments, and has been exemplified as a self-powered device for movement monitoring and information transmission. These capabilities may promote future biomedical applications such as the treatment of neurological and cardiovascular diseases.