Transport Mechanisms of Hydrogen Gas and Ions in Poly(potassium acrylate) Electrolytes

Poly(potassium acrylate) (PAAK) in high concentration KOH solutions is a promising electrolyte for use in alkaline zinc batteries. Atomistic molecular dynamics simulations are used to investigate the transport mechanisms of hydrogen gas and zincate ions through both KOH solutions and PAAK solutions with comparable concentrations of KOH. Hydrogen molecules do not interact with the ions or the polymer, and simply diffuse through the system. Their diffusion constant decreases with both increasing KOH concentration and when in the polymer, due to the increased viscosity of the solution. By contrast, zincate ions form long-lived clusters with the PAAK chains which significantly slow their diffusion.