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Enabling stable aqueous Zn metal anodes by scandium acetate electrolyte additives
Citation
Chen, C., Li, L., Long, Z., Ang, E. H., & Liang, Q. (2024). Enabling stable aqueous Zn metal anodes by scandium acetate electrolyte additives. Journal of Materials Chemistry A. Advance online publication. https://doi.org/10.1039/d4ta02133a
Abstract
The potential of zinc metal anode (ZMA) in emerging aqueous electrochemical devices like rechargeable zinc-ion batteries and hybrid capacitors is substantial, owing to its high theoretical capacity, low redox potential, non-toxicity, abundant availability, and cost-effectiveness. However, the practical application of ZMA faces limitations due to issues such as uncontrolled zinc dendrites growth and side reactions. In this study, we demonstrate that simultaneously incorporating scandium ion (Sc3+) and acetate anion (Ac‒) as electrolyte additives in the common ZnSO4 solution significantly enhances the cycling stability and reversibility of ZMAs. Our findings reveal that the Ac‒ acts as a pH regulator, dynamically buffering the electrolyte pH to around 4.3, effectively suppressing water-induced side reactions. Additionally, the synergistic effect of Sc3+ and Ac‒ (Sc3+/Ac‒) facilitates the desolation process of Zn2+ and lowers the energy barrier for electrochemical Zn plating, resulting in uniform Zn plating without noticeable zinc dendrite growth. Consequently, Zn‖Zn symmetric cells utilizing the Sc3+/Ac‒ electrolyte additive exhibit an ultra-long lifespan exceeding 1000 hours at 2.0 mA cm‒2 and 1.0 mAh cm‒2. Moreover, the Zn‖Cu cell demonstrates a high average Coulombic efficiency of 98.45% after 400 plating/stripping cycles at 1.0 mA cm‒2 and 1.0 mAh cm‒2. Notably, when paired with an activated carbon (AC) cathode, Zn‖AC hybrid capacitors maintain a high-specific capacity of 62 mAh g‒1 after 10,000 cycles at 1.0 A g‒1. The research outcomes indicate that Sc3+ cooperated with Ac‒ are the promising electrolyte additive for achieving highly stable aqueous ZMAs.
Date Issued
2024
Publisher
Royal Society of Chemistry
Journal
Journal of Materials Chemistry A
DOI
10.1039/d4ta02133a