Facile Polyiodides Conversion Enabled by Facet Engineering for Durable Zinc-Iodine Batteries.

Abstract

Aqueous zinc-iodine (Zn-I2) batteries are highly promising for grid-scale energy storage, yet their practical viability is severely plagued by the polyiodides shuttle effect and sluggish liquid-solid conversion kinetics, which fundamentally arise from the contradictory energetic demands between soluble intermediate confinement and solid-product desorption. Herein, we rationally construct a dual-facet spinel cobalt oxide to precisely decouple these competing interfacial behaviors. By regulating the proportional exposure of strongly coordinating (100) and weakly coordinating (111) facets, a tailored surface microenvironment is constructed that effectively circumvents the inherent thermodynamic trade-off, breaking the single adsorption limitation intrinsic to uniform catalysts. In situ iodine L3-edge X-ray absorption spectroscopy and three-dimensional synchrotron-based nanocomputed tomography reveal that this specific facet modulation substantially reduces the activation barrier for rate-determining polyiodides oxidation, facilitating spatially uniform solid-iodine deposition. Driven by these structural advantages, the assembled Zn-I2 batteries with c/o-Co3O4 deliver a high specific capacity of 161.1 mAh g-1 at 16 A g-1 and an ultralow capacity decay rate of 0.00055% per cycle after 50,000 cycles at 10 A g-1. Furthermore, the batteries also exhibit a broad operational temperature ranging from -30 to 60 °C, highlighting the strong potential for practical applications. This work provides a perspective on facet engineering for achieving wide-temperature-tolerant aqueous iodine storage.

Abstract as supplied by the indexing source. © the authors / publisher.