Positively Charged Quasi-Metal–Organic Framework to Reconstruct an Electric Double Layer for a Durable Zn Metal Anode
Caixia Li, Kai Zhang, Pengxian Li, Jingwen Liu, Ming Fu, Yuanxiang Gu, V. Z. Turkevich, Lei Wang, Qiang Xü
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 SO 4 2– anions as transfer sites for Zn 2+, leading to a homogeneous ion distribution within the inner Helmholtz plane (IHP). Therefore, the distribution of Zn 2+ –H 2 O–SO 4 2– in the EDL has been adjusted due to the regulating effect by a SEI. Besides, the regulated EDL reduces the concentration of SO 4 2– and free H 2 O in the IHP, thus promoting uniform Zn 2+ 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 ).