Stable zinc anode with ionic conductive interface layer for high performance aqueous zinc-ion batteries

Aqueous zinc ion batteries (AZIBs) are considered promising for the future large-scale energy storage applications due to their intrinsic high safety, low cost, environmental benignity and competitive energy density. However, the side reactions and dendrite growth of zinc metal anode result in low Coulombic efficiency and inferior cycle stability, which hinders the deployment of AZIBs in large scale applications. Herein, an organic-inorganic composite layer with rapid Zn2+ diffusion path is fabricated on the surface of the zinc metal anode, which is composed of polyvinyl butyral (PVB) and Cu-Zn alloy nanoparticles. The composite layer works as an artificial solid electrolyte interphase (SEI) layer with surface hydrophobic, even Zn2+ flux and low nucleation energy that suppresses Zn dendrite growth and surface H2 evolution reaction during the repeated zinc deposition/stripping. As a result, the surface protected Zn anode (p-Zn) is very stable over 2700 h in symmetrical cells at 0.5 mA/cm2-0.5 mAh/cm2 condition. The full cell coupled with VO2 cathode stably cycles 1000 cycles with an average Coulombic efficiency of 99.945% at the current of 1 A/g. Furthermore, p-Zn||VO2 pouch cells are assembled and achieve more than 330 cycles at the current of 1 A/g with no swelling or leakage of electrolyte. The work presented here provides a simple and feasible strategy for the protection of zinc anodes and has great potential for practical applications.

Automated summary

This study fabricates an organic-inorganic composite layer on the surface of zinc metal anode, which provides a rapid diffusion path for Zn2+ and suppresses dendrite growth and H2 evolution reaction. Experimental results show that this layer enables stable performance of the zinc anode under various test conditions, with 1000 cycles achieved in combination with VO2 cathode.