A computational model of a liquid e-fuel cell

A new energy storage system that utilizes electrically rechargeable liquid fuels (e-fuels) obtainable from diverse electroactive materials has been recently proposed. The system is composed of an e-fuel charger to charge e-fuels and an e-fuel cell to generate electricity for end use. Here, we develop a model for a liquid e-fuel cell by incorporating fluid flow and mass/charge transport processes coupled with electrochemical reactions of the involved electroactive species. The mathematical model is validated against the experimental data in the open literature. The model allows to study the effects of various operation variables, including e-fuel concentration, sulfuric acid concentration, e-fuel flow rates, as well as structural design parameters, including the anode porosity and thickness, the membrane and cathode catalyst layer thickness, on the cell performance. The simulation results reveal that the cell performance improves with increasing e-fuel concentration, sulfuric acid concentration, and e-fuel flow rate. As for the aforementioned structural design parameters, the cell performance increases with increasing these parameters except the membrane thickness where performance degradation is found. This study therefore provides insights into the performance-enhancing and performance-limiting parameters, as well as the design optimization of the liquid e-fuel cell.