High-Efficiency Ion Channel Design For Fuel Cell Anion Exchange Membrane

Alkaline anion exchange membrane fuel cell（AEMFC）have attracted numerous attentions from researchers in recent years,since it has the advantages of fast cathode reaction kinetics,allow using of non-precious metal catalysts and less corrosion issues.As one of the key components of alkaline fuel cells,anion exchange membrane（AEM）plays an important role in isolating oxygen from hydrogen,and conducting ions.However,there are still problems that need to be solved,such as low ionic conductivity,poor basic stability,and poor mechanical properties.Traditional idea for AEM design is to increase high ion exchange capacity（IEC）,so as to improve the ionic conductivity.Thinking out of the box,this thesis fabricated highly conductive AEM by constructing a high efficient hydrophilic ion channel at low IEC.The main tasks of this thesis are:（1）Quaternized cellulose（QCNC）/quaternized polyphenylene ether（QPPO）composite AEM.Amino silane was grafted on the surface of CNC to acquire QCNC,and blended with QPPO to fabricate QCNC/QPPO composite membrane.TEM image revealed that QCNC were well distributed in QPPO matrix,and formed a clear network,leading to improved ion conductivity compared with pure QPPO.For example,2 wt%QCNC/QPPO membrane possessed a conductivity of 160%(60 mS cm^-1,80°C)of that of QPPO.Furthermore,H₂/O₂ cell performance of membrane electrode assembly based on 2 wt%QCNC/QPPO AEM showed an excellent peak power density of 392 mW cm^-2 at 60°C without back pressure,whereas that of neat QPPO AEM was only 270mW cm^-2.（2）QPPO electrostatic spinning nanofiber/polyvinyl alcohol（PVA）composite membrane.QPPO nanofiber was prepared by electrostatic spinning,and added into PVA matrix to fabricate composite membrane.The results showed that,the diameter of QPPO nanofiber was around 200 nm,the nanofiber was compatible with PVA matrix,and the mechanical properties of the composite membrane were quite good.The conductivity test results show that the conductivity of the 50 wt%QPPO/PVA composite membrane is nearly 34%higher than that of the QPPO homogeneous membrane.The formation of ion channels by conductive nanofibers is expected to increase the ionic conductivity of anion exchange membranes at low IEC.