Stabilizing zinc anode via a chelation and desolvation electrolyte additive

Abstract

The uncontrollable dendrites growth and intricately water-induced side reactions occurred on zinc anode leads to safety issues and poor electrochemical kinetics, which largely limit the widespread application of zinc-ion batteries (ZIBs). Herein, ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) is utilized as an electrolyte additive to strengthen the reversibility and cycling stability of zinc anode. Experimental results and theoretical calculation demonstrate that the EDTA-2Na presents a much stronger coordination with Zn2+ when comparing with H2O molecular, implying the EDTA-2Na is capable to enter the solvation shell of [Zn(OH2)6]2+ and coordinate with Zn2+ ions, thus achieving a flat and smooth zinc deposition with less by-products (Zn4SO4(OH)6·xH2O and H2). Consequently, the zinc symmetric battery with EDTA-2Na additive delivers an excellent cycling stability up to 1800 h under current density of 1 mA cm-2, and the hydrogen evolution reaction (HER), corrosion, by-product issues are significantly inhibited. Moreover, the rate performance and stability of coin-type and pouch-type Zn||MnO2/graphite batteries are significantly boosted via EDTA-2Na additive (248 mAh g-1 at 0.1 A g-1, 81.3% after 1000 cycles at a A g-1). This kind of electrolyte additive with chelation and desolvation functions shed lights on strategies of improving zinc anode stability for further application of ZIBs.

Keywords

• Zinc-ion battery
• Zinc anode
• Dendrites
• EDTA-2Na
• Desolvation