2025 AIChE Annual Meeting

(648i) Regulating Zinc Electrodeposition on Anode Using Polymer Electrolytes

Author

Duhan Zhang - Presenter, Cornell University
Ensuring the reversible electrodeposition of metals at liquid-solid interfaces is crucial for the long cycle life of rechargeable batteries that employ metals as anodes. While extensive research has focused on the electrochemical transformations influencing reversibility, the fundamental hurdles related to maintaining morphological control when an intrinsically crystalline solid metal phase emerges from an electrolyte solution have received less attention. However, these interfacial challenges present significant opportunities for advancement.

Here, we propose methods to stabilize fluid mechanics at the interface and reshape initial growth and orientation of crystalline metal electrodeposits. With high molecular weight polymers, at polymer concentrations above the entanglement threshold, high molecular weight polymers impart elasticity to liquid electrolytes which dampen electroconvective flow at a cation-selective interface but have at most a minimal effect on the bulk ionic conductivity of the liquid. These polymer additives have a large beneficial effect in extending the range of electric potentials where stable electrodeposition is observed. With low molecular weight polymers, the polymer-salt complexes (polymer-Zn2+-aX−) (where a = 1,2,3) spontaneously formed in aqueous electrolytes containing zinc (Zn2+) and halide (X−) ions to regulate electro-crystallization of zinc. Specifically, we demonstrate that when X = Iodine (I), these complexes facilitate the electrodeposition of zinc in a hexagonal closest packed morphology, with the (002) plane preferentially oriented parallel to the electrode surface. This precise control over zinc electrodeposition morphology on planar substrates leads to exceptional anode reversibility and unprecedented cycle life. We validate the practical benefits of this approach through studies on Zn-I2 full battery cells, implemented in both coin cell and single-flow battery cell configurations.