Employing a chelating agent as electrolyte additive with synergistic effects yields highly reversible zinc metal anodes

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-03, Vol.53 (1), p.451-4511
• Main Authors: Feng, Ziwen, Zhang, Yu, Yao, Lingmin, Deng, Qinglin, Tan, Yipeng, Zhao, Yang, Li, Zelin, Lu, Linfei
• Format: Article
• Language: English
• Subjects: Additives; Anodes; Calcium ions; Cations; Chelating agents; Chelation; Cycles; Electrolytes; Electrolytic cells; Electrostatic shielding; Interface reactions; Rechargeable batteries; Solvation; Synergistic effect; Zinc
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt04030e

Aqueous zinc ion batteries (AZIBs) have attracted sustained attention owing to their intrinsic safety and low cost. Unfortunately, the dendrite growth and parasitic side reactions of metallic zinc anodes severely degrade the cycling stability of the batteries and limit the practical application of AZIBs. In this work, calcium gluconate (CG), a chelating agent, as a novel electrolyte additive was introduced to tackle the thorny issue of zinc anodes in a 2 M ZnSO 4 electrolyte by the synergistic effects of gluconate (GA − ) anions and Ca 2+ cations. Experimental characterization and computational simulations confirmed that the incorporation of GA − can not only mitigate the precipitation of Ca 2+ ions, but also affect the primary solvation shell (PSS) of Zn 2+ and modulate the electrode/electrolyte interfacial reaction, thereby inhibiting side reactions. Besides, trace amounts of Ca 2+ cations can preferentially adsorb on the surface of the zinc anode tip, forming an electrostatic shielding shell that guides the uniform deposition of zinc ions. The Zn//Zn symmetric cells achieved a remarkably prolonged cycling lifespan ranging from 174 h to 3745 h at 6.37 mA cm −2 and 2.88 mA h cm −2 with an ultrahigh cumulative plating capacity (CPC) of about 11 900 mA h cm −2 . Even at a higher current density of 5 mA cm −2 and an areal specific capacity of 5 mA h cm −2 , Zn//Zn cells with the CG additive cycled for 248 h, about 5 times better than that without the CG additive. These results pave the way for the exploitation of new electrolyte additives with synergistic effects in AZIBs. Calcium gluconate additives can effectively suppress the side reactions of Zn anodes with a synergistic effect of Ca 2+ and GA − in regulating the Zn 2+ solvation structure and modulating the electrode/electrolyte interface.