Abstract:
A membrane separator is one of the main components in zinc-air batteries playing an important role in controlling the mass transfer for the electrochemical reaction in the battery which determines the battery performance. This work aimed to develop a new membrane separator for the zinc-air battery. Polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and their blends were used for the fabrication of separator in this work. In addition, an inorganic nanoparticle with high hydroxide content such as MCM-41 was also applied as the filler for the polymers. The results revealed that the addition of PAN in PVA enhanced the electrolyte uptake and ionic conductivity of the resultant membranes. However, the addition of PAN at high content (>30-50 wt.%) worsened alkaline electrolyte stability of the membrane, leading to a decrease in battery performance. On the other hand, the addition of PVP in PVA had no significant influence on the membrane properties and the zinc-air battery performance. When adding a small amount (2.5 wt.%) of MCM-41 in PVA and PVP/PVA blend, the performance of primary zinc-air batteries was improved. Discharge capacity efficiency at 49% and energy density efficiency at 41% were obtained from using membrane with 2.5 wt.% MCM-41 in PVA. However, its battery cycle in rechargeable battery performance was reduced. In addition, the addition of PVP in PVA could promote zincate crossover, leading to a lower rechargeable cycle. The highest rechargeable zinc-air battery at 163 cycle was obtained from using pure PVA membrane.
