Sulfated cellulose nanofibrils-based hydrogel moist-electric generator for energy harvesting

The excellent hydrophilicity of hydrogel makes it an ideal material for moisture-enable electricity. However, the lack of efficient protonation or ion diffusion leads to poor moisture-electric performance. Herein, a nanocellulose-base hydrogel moisture-electric generator (N-HMEG) is developed by composed of sulfated cellulose nanofibers (SCNF) and polyvinyl alcohol (PVA) with glycerol-water binary solvent. The SCNF and glycerol promote the ion diffusion and hygroscopicity of hydrogel, respectively. A N-HMEG can generate an open-circuit voltage of 0.9 V and short-circuit current density of 92 μA cm−2 at 80 % relative humidity. The remarkable performances of N-HMEG can be attributed to the synergistic effect of asymmetric ionic diffusion and redox reaction on the electrode. Furthermore, the large-scale integration of N-HMEGs can be easily accomplished to deliver a voltage of up to 102 V with 130 units in series. The integrated N-HMEGs are demonstrated to provide power for commercial electronics. This work provides an effective method for designing of moisture-electric generators, which will facilitate the development of green power sources in the future.