Positively Charged Quasi-Metal-Organic Framework to Reconstruct an Electric Double Layer for a Durable Zn Metal Anode.

Abstract

To reveal the construction principle of an electric double layer (EDL) on a Zn anode, a positively charged artificial solid electrolyte interphase (SEI) is established by a quasi-metal-organic framework with open metal sites (OMSs). As illustrated by theoretical calculation and in situ Raman and Fourier transform infrared spectroscopy characterization, the OMSs are introduced successfully and unsaturated Ce sites bond with SO₄^2- anions as transfer sites for Zn²⁺, leading to a homogeneous ion distribution within the inner Helmholtz plane (IHP). Therefore, the distribution of Zn²⁺-H₂O-SO₄^2- in the EDL has been adjusted due to the regulating effect by a SEI. Besides, the regulated EDL reduces the concentration of SO₄^2- and free H₂O in the IHP, thus promoting uniform Zn²⁺ deposition and anticorrosion properties of the Zn anode. As a result, the Q-Ce-808@Zn anode demonstrates exceptional cycling stability over 4200 h (1 mA cm^-2) and 1300 h (20 mA cm^-2).