Nanofluidic osmotic power generator demonstrated in polymer gel electrolytes with substantially enhanced performance
Polymer gel electrolytes have shown potential for enhancing operation stability and cycle longevity in energy storage devices; however, their use in osmotic power conversion remains unexplored, because one would expect reduced ionic conductance at the nanoscale, which in turn can impact its performance output. Here we report the first polymer gel electrolyte-based nanofluidic osmotic power generator by introducing the polyvinyl alcohol (PVA) as a solid matrix. We present the experimental evidence showing that with the PVA gel electrolytes, the ion transport, as well as the osmotic power can be enhanced at conditions at which the electric double layer overlap effect in nanochannels is significant; thus, a substantial increase of the power output as high as nearly two times can be achieved as compared to the corresponding aqueous electrolytes. The observations are explained by the adsorption of excess counterions to the PVA confined at the nanoscale, supported by our modeling performed by the modified Poisson and Nernst-Planck equations with considering a charged PVA layer in a nanochannel. The system presented offers a new avenue toward exploitation of high-performance and safe osmotic power generator.