In this study, we proposed a hydrophobic liquid ionic conductive agent to mediate confined iodine transport in thick electrode, realizing highly stable zinc-iodine battery with ultra-high iodine mass loading.
Due to the high solubility, high reversibility, and low cost of iodide, iodine-based redox flow batteries (RFBs) are considered to have great potential for upscaling energy storage. However, their further development has been limited by the low capacity of I − as one-third of the I − is used to form I 3− (I 2 I −) during the charging process.
Why are zinc-iodine flow batteries important?
Zinc-iodine flow batteries have attracted huge attention for distributed energy storage devices owing to high inherent safety, suitable redox potential, and superior solubility.
How iodine is used in a battery?
For example, in flow batteries, the generated I 2 needs to be converted into a highly soluble I 3- to avoid the deposition of elemental iodine on the electrode surface and block the electrolyte transport pathway, but in static batteries, the positive electrodes generally have strong adsorption to confine iodine to avoid shuttle effect.
What is a redox flow battery?
Redox flow batteries (RFBs) or flow batteries (FBs)—the two names are interchangeable in most cases—are an innovative technology that offers a bidirectional energy storage system by using redox active energy carriers dissolved in liquid electrolytes.
Is iodine a good energy storage reaction?
Due to the insulating properties of iodine, it will bring extremely high battery polarization, and the reversibility and reaction priority are much smaller than the reaction in (2). Therefore, the reaction that generates iodine element in the flow battery is not suitable as an energy storage reaction.
What are zinc poly halide flow batteries?
Zinc poly-halide flow batteries are promising candidates for various energy storage applications with their high energy density, free of strong acids, and low cost . The zinc‑chlorine and zinc‑bromine RFBs were demonstrated in 1921, and 1977, respectively, and the zinc‑iodine RFB was proposed by Li et al. in 2015 .