Simulation of Proton Transport in Proton Exchange Membranes with Reactive Molecular Dynamics

Proton exchange membrane fuel cells (PEMFCs) are promising to become the next generation of energy conversion devices that are efficient, lightweight, and have clean emissions. In these cells, a hydrated polymer membrane acts as an electrolyte layer through which protons travel. Due to the complex nature of the membranes used, the optimization of fuel cell performance is a difficult task, and relies on a number of factors, such as hydration level, polymer side chain length and composition, equivalent weight, morphology, and chemical and mechanical stabilities. Molecular dynamics is a particularly powerful tool for studying PEMs, as it provides the computational efficiency to study length and time scales relevant to these systems. In this review, we present results from several computational papers that use reactive molecular dynamics, which explicitly describe bond breaking and formation, to study proton transport in several polymers commonly used in PEMs. The results presented demonstrate the importance of the interaction between hydronium and the charged side chains and the morphology on the performance of PEM fuel cells.