Developments of alkaline solid polymer electrolyte membranes based on polyvinyl alcohol and their applications in electrochemical cells

Alkaline solid polymer electrolyte membranes (ASPEM) have been extensively studiedfor the varied electrochemical device applications due to the thinner thickness, lowerelectrolyte permeability, higher ionic conductivity and ease in processibility. We prepared aseries of ASPEM based on polyvinyl alcohol (PVA) polymers such as PVA/KOH,PVA/PEO/KOH, PVA/KOH/glass-fiber-mat, PVA/PECH, PVA/TEAC, PVA/PAA, andPVA/PAA/PP/PE composites. These new material systems were introduced with uniqueimprovements for fuel cell applications. They have not only the potential to lower theprocessing cost but also can provide high ionic conductivity. The PVA/PAA polymer blendsystem exhibited high ionic conductivity of 0.301 S cm^-1 and the anionic transport numbercould reach 0.99, both at room temperature. For Zn/air and Al/air battery application, thepower density was as high as 90-110 mW cm^-2. The PVA-based composite SPE has greatpotential for use in alkaline battery systems. The progressive advancements in the science andtechnology of solid polymer electrolyte membranes are presented in this chapter.We will demonstrate the preparation techniques for ASPEM and the characterizationresults. The relationship between structure and properties will be discussed and compared.The double-layer carbon air cathodes were also prepared for solid-state alkaline metal fuel cellfabrication. The alkaline solid state electrochemical systems, such as Ni-MH, Zn-air fuel cells, Al-air fuel cells, Zn-MnO₂ and Al-MnO₂ cells, were assembled with anodes, cathodes andalkaline solid polymer electrolyte membranes. The electrochemical cells showed excellent cellpower density and high electrode utilization. Therefore, these PVA-based solid polymerelectrolyte membranes have great advantages in the applications for all-solid-state alkalinefuel cells. Some other potential applications include small electrochemical devices, such assupercapacitors and 3C electronic products.