Toward Forty Thousand‐Cycle Aqueous Zinc‐Iodine Battery: Simultaneously Inhibiting Polyiodides Shuttle and Stabilizing Zinc Anode through a Suspension Electrolyte

• Published in: Advanced functional materials 2023-07, Vol.33 (28), p.n/a
• Main Authors: Chen, Guanhong, Kang, Yuanhong, Yang, Huiya, Zhang, Minghao, Yang, Jin, Lv, Zeheng, Wu, Qilong, Lin, Pengxiang, Yang, Yang, Zhao, Jinbao
• Format: Article
• Language: English
• Subjects: Battery cycles; Chemical precipitation; Corrosion effects; Corrosion products; Electrolytes; Energy storage; Interlayers; Iodine; Ion accelerators; Materials science; Self-assembly; shuttle effect of polyiodides; suspension electrolytes; Vermiculite; vermiculite nanosheets; Zinc; zinc‐iodide batteries; Zn corrosion
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202300656

Aqueous zinc‐iodine (Zn‐I2) batteries are promising candidates for grid‐scale energy storage due to their safety and cost‐effectiveness. However, the shuttle effect of polyiodides, Zn corrosion, and accumulation of by‐products restrict their applications. Herein, a simple vermiculite nanosheets (VS) suspension electrolyte is designed for simultaneous confinement of polyiodides and stabilization of Zn anode. It is found that the generation of I5− as dominant intermediate and the precipitation reaction between I5− and alkaline by‐products should cause irreversible iodine species loss. Benefiting from the high binding energy between polyiodides and silica‐oxygen bonds of VS, dissolved polyiodides are effectively anchored on the surface of VS suspended in the bulk electrolyte to suppress the shuttle effect, which is confirmed by in situ Raman, Ultraviolet‐visible characterizations and theoretical calculations. Furthermore, the self‐assembly VS interfacial layer on the surface of Zn anode hinders side reactions induced by polyiodides. Meanwhile, the interlayer and surface excess negative charges of VS tend to be compensated by Zn2+ from diffuse layer, which serves as ion accelerators for transferring Zn2+ at the interface immediately, rendering dendrite‐free Zn plating/stripping behavior. Consequently, the Zn‐I2 battery with VS electrolyte achieves an ultra‐long lifespan of 40000 cycles with a negligible capacity decay at 20 C. Vermiculite nanosheets (VS) electrolyte is designed to restrain the shuttle effect of polyiodides and stabilize Zn anode for high‐performance zine‐iodine batteries. Polyiodides can be effectively anchored on the VS surface owing to exposed silica‐oxygen bonds, which are proved by in situ Ultraviolet‐visible spectra. VS interfacial protective layer can prevent reaction between leaked polyiodides and Zn anode, while serving as Zn2+ accelerator for dendrite‐free deposition.