Modeling Migration-Diffusion-Reaction Processes in an Idealized Lithium-Sulfur Cell

G. Minton [1], R. Purkayastha [1], S. Walus [1], M. Marinescu [2], T. Zhang [2], G. Offer [2],
[1] Oxis Energy Ltd, Oxford, United Kingdom
[2] Imperial College London, London, United Kingdom
Published in 2016

During the basic operation of a lithium-sulfur (Li-S) cell, sulfur molecules are required to undergo a complex mix of electrochemical and chemical reaction processes. To date, almost all modeling of Li-S cell behavior has been undertaken using electroneutral, structurally homogenized, cell scale models accounting for most of these processes. The presented work was undertaken in order to try and understand whether relaxing some of the constraints of homogenized models, most importantly that of electroneutrality, can help us better understand reaction processes in systems similar to a Li-S cell. By accounting for the electric double layer (EDL), surface interactions can be better described, including the effects of relative species sizes in the liquid phase. We find that it is possible to recreate some trends seen in the discharge curve for a Li-S cell. The precipitation and dissolution processes do appear to be required.