Missing-Linker Bifunctional Mil-125(Ti)-Zn Interface Modulation Layer to Simultaneously Suppress Hydrogen Evolution Reaction and Dendrites for Zn Metal Anodes

Abstract

Rechargeable Zn-based aqueous batteries have attracted rising attention due to their inherent safety, high capacity and cost-effectiveness. Unfortunately, the cycling performance and Coulombic efficiency of zinc anode are far from satisfactory because of the uneven plating/stripping process and competitive hydrogen evolution reaction (HER) in zinc metal batteries. Herein, we construct a missing-linker bifunctional MIL-125(Ti)-Zn as the interface modification layer of zinc metal anode. MIL-125(Ti)-Zn obtained electron-rich oxygen sites through the missing-linker, which can effectively regulate the diffusion behavior of Zn 2+ through low Zn 2+ diffusion barrier. In addition, strong adsorption of H* on oxygen sites inhibits the release of hydrogen, so as to suppress HER and dendrites for Zn metal anode. Based on this synergistic effect, MIL-125(Ti)-Zn has a low hydrogen evolution current density -21.4 mA cm –2 at −1 V and weak activity for HER. The symmetric cell based on MIL-125(Ti)-Zn@Zn anode exhibits favorable cyclicality for over 2100 h with voltage hysteresis of ~80 mV at 1 mA cm −2 , showing the nearly incremental quantity of eleven and fortyfold in cycle life compared with MIL-125(Ti)@Zn anode and bare Zn anode, respectively. This MIL-125(Ti)-Zn@Zn anode also releases a high CE of 99.01% at 1 mA cm −2 .

Keywords: zinc metal anode, metal organic framework, missing-linker, dendrite, HER