Shuttle Suppression in Zinc-Iodine Batteries via a Gd/Eu Co-Doped Cerium Oxide Modified Separator.

Abstract

Zn-I₂ batteries have emerged as a compelling electrochemical energy storage platform, benefiting from their excellent theoretical capacity, inherent safety, and low cost. Nevertheless, their development, especially on the separator, is impeded by the severe shuttle of polyiodides and sluggish reaction kinetics. To address these challenges, this work demonstrates the design of Gadolinium (Gd) and Europium (Eu) co-doped cerium oxide (CeO₂) nanoparticles as a functional separator coating, utilizing experimental techniques paired with density functional theory (DFT) calculations to evaluate performance. The results reveal that Gd/Eu co-doping modulates the electronic structure of CeO₂, providing abundant active sites that strongly chemisorb polyiodides and act as excellent electrocatalysts to accelerate the reversible conversion between I₃ ^- and I^-. Consequently, the batteries employing the Ce_0.96Gd_0.02Eu_0.02O₂ coating effectively suppress the polyiodide shuttle, exhibiting outstanding high-rate performance with a capacity of 193 mAh g^-1 at 10 A g^-1 and maintaining stable cycling for 50,000 cycles. This study provides a potential pathway for fabricating high-performance Zn-I₂ batteries by integrating adsorption and catalytic conversion functions into a single separator modification.