Augmentation of the reverse electrodialysis power generation in soft nanochannels via tailoring the soft layer properties

Nanochannels covered with a polyelectrolyte layer (PEL) are recently shown to increase the power generation by reverse electrodialysis (RED) considerably. In this investigation, we numerically study the influences of the electrolyte-PEL property difference on the RED energy conversion in conical-shaped nanochannels covered with dense polyelectrolyte layers. The current-voltage aspects of the nanochannel are determined through solving the Poisson-Nernst-Planck and the Navier-Stokes-Brinkman equations for steady-state conditions while taking into account different values of the dielectric permittivity, diffusion coefficient, and viscosity for the electrolyte and the PEL. The results indicate a relatively high sensitivity of the maximum energy conversion efficiency and the maximum power generated to the PEL-electrolyte property difference, especially at moderate and high values of the high-to-low concentration ratio. This implies that the RED power generation characteristics may be effectively controlled via tailoring the PEL structure. More specifically, both the efficiency and the maximum rate of power generation may be increased by densely distributing the polyelectrolyte brushes. For example, a power density of 75W.m−2 can be obtained by using a dense PEL with the thickness 5nm, a value that is impossible to achieve even with thicker PELs when the properties of the electrolyte and PEL are the same.