PERFORMANCE ENHANCEMENT OF A FLEXIBLE PRINTED ZINC–AIR BATTERY BY IMPROVING ELECTROLYTE SYSTEM

Abstract

Flexible printed zinc-air battery is an energy storage technology which has the high energy density. However, the difference between theoretical and practical energy densities is quite high. Therefore, in this study, zinc utilization in flexible printed zinc-air battery was enhanced by adding anionic surfactants in 7 mol L-1 KOH which is a traditional electrolyte. These surfactants which are employed consisted of sodium dodecyl benzene sulphonate (SDBS) and sodium dodecyl sulfate (SDS). In addition, an ethanol was also used to improve SDBS and SDS capabilities. Then the battery cells which used various modified electrolytes were examined by the battery analyzer. Additionally, the surface of discharged zinc electrodes was investigated by scanning electron microscope. The results reveal that the capacity and the energy of the batteries are doubled by using SDBS and SDS modified electrolyte. The use of SDS modified electrolyte without ethanol is higher capacity and energy than the use of SDBS additive. The proper concentration for a flexible printed zinc-air battery of both SDBS and SDS is 0.4 mol L-1. Both SDBS and SDS modify the zinc electrode surface to become more porosity, leading to improve the wettability of zinc electrode. Therefore the modified electrolytes can easily penetrate to the zinc electrode, resulting in improvement of active species diffusion. Moreover, addition of ethanol in the modified electrolytes can improve SDBS and SDS capabilities when the surfactant concentration is higher than their critical micelle concentration and the surfactant molecule with the large molecular structure is employed. Furthermore, characteristics of surfactants (such as molecular structure and the CMC) should be taken into account because they also affect the battery performance.