NMR study of proton transport in novel polymer electrolyte composites

Project description:

Proton transport is an important process in many biological systems as well as electrochemical devices including fuel cells, redox flow batteries, sensors and electronics. As a vital component of many electrochemical devices, the polymer electrolyte membrane (PEM) is generally required to exhibit outstanding performances in multi-dimensions including ionic conductivity, mechanical property, (fuel) barrier property, and chemical stability, particularly in the presence of oxygen free radicals. A single component material can rarely fulfil all the multi-dimensional requirements. Therefore, multi-component (binary or ternary) and/or multi-level structured materials has been developed to achieve a good overall performance PEM materials for various devices applications. As an example,  we have recently developed protic organic ionic plastic crystal (POIPC) and PVDF nano fibre composites¹, and we found that the POIPC interacts strongly with the PVDF nanofiber at the interface.  Metastable phase was stabilized by the inert PVDF matrix and thus the proton conductivity was enhanced significantly.

Despite of the great success of composite materials, the fundamental understanding of the ion transport in these complex systems still remains largely unknown. For example, we don’t have a clear picture of the proton transport pathways in these systems, and neither do we know how to control proton transport through a careful design of polymer chemistry. In this respect, NMR sits in perfectly- it allows us to probe ion transport and molecular dynamics at a molecular level and with an atomic resolution². In this project, a range of new proton conducting membrane materials based on poly(ionic liquid)s and POIPCs will be prepared. A combination of DSC, impedance spectroscopy, pulse-field NMR, solid-state NMR will be used to study the proton transport mechanisms in these composite electrolyte materials.