Acid-Treatment-Assisted Liquid Metal–Based Zinc Metal Anode for Stable Aqueous Zinc-Ion Batteries

Abstract

Aqueous Zn-ion batteries (AZIBs) are considered to be a promising alternative to Li-ion batteries (LIBs) owing to the low cost, superior safety, and high theoretical capacity of the Zn anode (820 mAh g⁻¹ and 5855 mAh cm⁻³). However, Zn metal anodes encounter challenges, mainly including the formation of unfavorable byproducts and the growth of Zn dendrites. Furthermore, Zn metal corrosion and the hydrogen evolution reaction (HER) are issues related to AZIBs. To overcome these issues, we engineered a Zn metal surface using acid treatment and eutectic GaIn–liquid metal (EGaIn–LM) coating. Coating EGaIn–LM on the Zn metal anode results in an liquid–liquid interface between the electrolyte and electrode, increasing wettability and accelerating charge transfer kinetics, with respect to a bare Zn metal anode. Furthermore, the EGaIn–LM coating improved corrosion resistance and reduced the HER owing to the high overpotentials of the reaction with Ga and In. Based on these advantages, EGaIn–LM@acidified Zn (EGaIn–LM@AZn) anodes showed stable symmetric cycling over 420 h and exhibited high stability against the formation of byproducts and Zn dendrites. Finally, we prepared V₂O₅ cathode–based full cells with different anodes. The V₂O₅//EGaIn–LM@AZn full cell demonstrated excellent rate capability, long-term charge/discharge cycling (capacity retention of 71.8% after 1500 cycles at a current density of 5 A g⁻¹), and high specific capacities under various current densities owing to improved charge transfer kinetics and the protective nature of EGaIn–LM. The proposed simple EGaIn–LM coating method may offer a promising strategy to prepare a stable Zn anode.