Highly stable anion exchange membranes: synthesis and electrochemical applications

Abstract

Anion-exchange membranes (AEMs) can be used in several electrochemical devices for the production of clean energy and value-added molecules. The society is progressing to a renewable energy based economy and there is a serious global commitment to reduce the emission of greenhouse gases. In this context, the need for multi-GW scale energy storage becomes imminent. One answer to this problem is the use of a hydrogen-based energy storage system generated by water electrolysis using electrons produced without carbon emission. In this scenario, AEMs are promising solid polymer electrolytes for cheap and compact water electrolyzers (AEMWE). The use of AEMs in this type of device reduces the corrosion issues of the components, and allows replacing expensive materials with cheap and abundant ones. However, traditional AEMs are usually based on quaternary ammonium head groups that often offer poor chemical stability due to the susceptibility to hydroxide (OH-) attack. The need for more chemically and mechanically stable AEMs is the bottleneck of electrochemical technologies that use AEMs as the core component. In this context, an emerging class of new alkaline solid polymer electrolyte has been gaining increasing attention: the ionenes. Ionenes are polymers that incorporate cations directly into the polymer backbone. In this type of polymer, the number of degradation routes is reduced, making it simpler to find possible improvements. Poly(benz)imidazolium-based polymers, a type of ionene, have been showing improved chemical stability in high pH environments, affording high hydroxide conductivity, and have been successfully explored in many electrochemical devices. In view of this scenario, this proposal comprehends the synthesis of new modified and chemically stable poly(benz)imidazolium-based AEMs for AEMWE and methane conversion applications, as well as the testing of AEMs and ionomers produced in Brazil via radiation-grafting in AEMWEs. This development of new AEMs and AEMWE testing will be carried out during a 12-month stay at Simon Fraser University in Canada under the supervision of Professor Dr. Steven Holdcroft who is a leading scientist on this topic. (AU)