Suppression of Hydrogen Evolution Reaction by Modulating the Surface Redox Potential Toward Long‐Life Zinc Metal Anodes

Abstract

AbstractAqueous Zn metal batteries hold significant promise for large‐scale energy storage owing to their high safety and low cost. Nevertheless, severe corrosion and uncontrollable dendrite growth hinder the cyclic stability of Zn metal anodes. Herein, a porphyrin‐Zn(II) (ZnTBPP) based multifunctional artificial layer to stabilize Zn anodes by suppression of hydrogen evolution reactions is designed. This hydrophobic interfacial layer repels active water molecules and facilitates the electron transfer from Zn interface to the ZnTBPP layer, thereby increasing the inherent hydrogen evolution potential of Zn anodes. Differential charge density maps reveal that the electron cloud density of the charge transfer layer within the ZnTBPP layer is delocalized due to the electron‐withdrawing effect of Br‐containing functional groups in the ZnTBPP ligands, depleting the interfacial electrons of Zn metal anodes. As a result, H* exhibits a higher Gibbs free energy (∆GH*) of 0.75 eV on Zn with a ZnTBPP coating layer in contrast to bare Zn (0.55 eV), effectively suppressing H2 production. Specifically, the H2 evolution rate of ZnTBPP@Zn (4.06 µmol h−1 cm−2) is ≈2.2 times lower than that of bare Zn. The ZnTBPP@Zn//NaV3O8·1.5H2O full cells exhibit an ultra‐long cycling life of 10 000 cycles at 10 A g−1.