Solvent-mediated mechanism of Zn ion adsorption on SrTiO3-coated Zn anode surface of aqueous Zn ion batteries

초록

Aqueous zinc-ion batteries (AZIBs) are promising energy storage systems due to their intrinsic safety, environmental benignity, and high ionic conductivity. However, dendrite formation and parasitic reactions at the Zn anode-electrolyte interface hinder their long-term stability. While SrTiO3 (STO) coatings have been experimentally utilized to mitigate such issues, the underlying interfacial mechanism remains unclear. Here, ab initio molecular dynamics simulations are performed to elucidate solvent-mediated Zn ion adsorption behavior on the bare Zn surface and the STO coating layer. The STO surface spontaneously hydroxylates upon contact with aqueous electrolyte, forming hydroxyl groups that promote the generation of hydroxide ions within the Zn ion solvation environment. These hydroxide ions partially replace coordinated water molecules, reconstructing the solvation shell and weakening the hydrogen-bond network. As a result, the Zn ion exhibits a lower desolvation energy barrier and stronger adsorption on the STO surface than on bare Zn. The strong Zn-OH electrostatic interactions and disrupted solvation network synergistically enhance interfacial ion transfer kinetics. This work uncovers how STO coatings govern Zn ion interfacial processes through solvent-assisted mechanisms, offering mechanistic insight into the rational design of robust inorganic coating layers for stable and efficient Zn anodes in AZIBs.

키워드