The Renaissance of the Zn-Ce Flow Battery : Dual-Membrane Configuration Enables Unprecedentedly High Efficiency

While the zinc-cerium flow battery has the merits of low cost, fast reaction kinetics, and high cell voltage, its potential has been restricted due to unacceptable charge loss and unstable cycling performance, which stem from the incompatibility of the Ce and Zn electrolytes. Herein, a dual-membrane cell configuration with an ion transpiration hub is designed to enable the use of custom-assigned charge carriers, which block the notorious H⁺ poisoning on the zinc side, to mitigate the electrolyte incompatibility. The response characteristics of the ion transportation hub are first investigated via finite element modeling analysis for visualizing the ion distribution and elucidating the mechanism of the electric field regulation strategy. The system engineering renders the cell a high discharge voltage plateau of 2.3 V at 20 mA cm^-2, a high energy efficiency of 71.3% at 60 mA cm^-2, and a record average Coulombic efficiency of 94% during cycling, making the Zn-Ce battery unprecedentedly efficient and stable.