Blue Energy Extraction Performance by Polyelectrolyte-Coated Porous Electrodes: Effects of Opposing Polyelectrolyte...

In the capacitive mixing technique, the electrode used to extract blue energy is typically composed of a carbon-based porous electrode material. Polyelectrolyte (PE) surface coating on porous electrodes serves as an intermediate soft layer, which can significantly enhance the energy extraction performance (EEP). Herein, the blue energy extraction performance by using PE-coated electrodes is studied by a statistical thermodynamic theory, with the exploration of the interplay effects between opposing polyelectrolyte interactions and pore size. Because of the interaction between opposing PE coatings, the response of electrostatic properties in the pore to surface potential variations is enhanced during charging/discharging processes, leading to a better EEP. Both the surface charge accumulation and surface potential rise in the charging process can be raised as the results of PE coating. For the cases studied, the extraction efficiency can be promoted up to 45% compared with the cases of bare electrodes. For narrow pores, the PE promotion effects are suppressed by strong pore confinement. The optimal PE coating condition is determined by the competitive results between pore size (H) and polyelectrolyte chain length (N), with that Ĥ ≡ H/(2Nσ) being mostly in [0.1, 0.5], where σ is the PE segment diameter.