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 Zn 2+ when comparing with H 2 O molecular, implying the EDTA-2Na is capable to enter the solvation shell of [Zn(OH 2 ) 6 ] 2+ and coordinate with Zn 2+ ions, thus achieving a flat and smooth zinc deposition with less by-products (Zn 4 SO 4 (OH) 6 ·xH 2 O and H 2 ). 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||MnO 2 /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. • Stability and reversibility of zinc anode are significantly improved via the EDTA-2Na electrolyte additive. • The chelation and desolvation effects between EDTA-2Na and Zn 2+ contribute to the dendrites-free anode. • HER, corrosion, and by-products on zinc anode are effectively suppressed. • Rate capability and stability of full batteries are greatly boosted via EDTA-2Na additive.