A mechanical-electrokinetic battery using a nano-porous membrane

This study conducts an analytical and experimental investigation associated with energy transfer by using a nano-porous membrane. The calculated results indicate that the streaming potential held at a saturated value when the electrolyte concentration is below a certain critical value. After passing this threshold value, the streaming potential decays dramatically with the electrolyte concentration. The efficiency increased with an increase of surface charge density and with a decrease of concentration. Generally, higher maximum efficiency can be achieved at a smaller channel. However, as the pore diameter is varied, a maximum efficiency is encountered. The results indicate that the battery performance can be efficiently improved by the unipolar characteristic inside the nano-sized channel. Our experimental results verify the analytical results; the best efficiency obtained is 0.77% in our experiments at a nominal 200 nm pore size alumina membrane having a 2.1 cm diameter and a 60 µm thickness. The maximum output energy is 18 µW by using a nominal 20 nm pore size alumina membrane.