Next-Gen Zinc-I2 Batteries: High Capacity Meets Long-Term Durability

Researchers developed a novel Zn-I₂ battery design using Zn-SA-MoC/NCFs to overcome iodine’s limitations, achieving high capacity (230.6 mAh g⁻¹) and durability (90% retention after 20,000 cycles).

Aqueous zinc-ion batteries (ZIBs) have gained significant attention for their high safety, widespread availability of raw materials, and environmental compatibility.

Iodine, which is abundant in seawater (55 μg L⁻¹), holds great potential for use in zinc-iodine batteries due to its high theoretical capacity (211 mAh g⁻¹) and suitable redox potential (0.54 V).

However, iodine’s low electrical conductivity limits efficient redox conversion during energy storage. Furthermore, the formation of soluble polyiodides can migrate to the zinc anode, causing capacity degradation and zinc corrosion.

Addressing Key Challenges: Innovative Material Design

To address the existing issues in Zn-I₂ batteries, the research team presents the precipitation method to encapsulate molybdate ions into zeolitic imidazolate framework-8 (ZIF-8), followed by electrospinning and calcination to create free-standing porous carbon fibers with Zn single atom sites and molybdenum carbide clusters (Zn-SA-MoC/NCFs).

With the hierarchical porous carbon framework for favorable mass transfer, the integration of molybdenum carbides with single-atom catalysts is expected to amplify the adsorption capability to iodine species and modulate the catalytic activity with an optimal charge redistribution. Thus, the assembled Zn-I₂ batteries demonstrate a large specific capacity of 230.6 mAh g⁻¹ at a current density of 0.5 C (1 C= 0.211 mA cm⁻²) and the good capacity retention of 90% after 20,000 cycles.

Enhanced Electrocatalysis and Broader Implications

With the fundamental understanding of enhanced electrocatalysis by incorporating of Zn-SA with MoC clusters, the concept study on electronic structure modulation between hosts and iodine species demonstrates the basic principles for high-performing Zn-I₂ batteries and beyond.

This study is the first to demonstrate the manipulation of the electrocatalytic activity of MoC clusters via the incorporation of Zn-N₄ sites for iodine redox reaction. The electronic structure regulation strategy provides robust guidance for constructing advanced iodine catalysts and optimizing their battery performance.

Reference: “Exploring interfacial electrocatalysis for iodine redox conversion in zinc-iodine battery” by Song Chen, Jizhen Ma, Qianwu Chen, Wenshuo Shang, Jinshuai Liu and Jintao Zhang, 28 November 2024, Science Bulletin.
DOI: 10.1016/j.scib.2024.11.042

Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.