Enhanced interfacial Zn2+ desolvation kinetics by a π-electron-rich Janus catalyst for robust Zn–metal batteries†

Abstract

The application of zinc–metal-based batteries is hindered by the low thermodynamic stability of zinc anodes and the sluggish desolvation kinetics of the interfacial [Zn(H₂O)₆]²⁺ complex, which can induce serious side reactions and exacerbate dendrite formation. Herein, an innovative catalytic desolvation mechanism is proposed to manipulate the interfacial solvation structure by engineering a π-electron-rich (CO/CN configurations) covalent organic polymer (COP) layer as an interfacial catalyst. It was revealed that the π-electrons can trigger dissociation of the [Zn(H₂O)₆]²⁺ complex through an ortho-synergistic reaction process, which includes a nucleophilic reaction between electron-accepting C atoms at CO/CN sites and H₂O molecules and an electrophilic reaction between electron-donating sites near O and N heteroatoms and Zn²⁺. In situ characterization analysis combined with advanced theoretical calculations confirmed that such a catalytic desolvation process can dynamically induce contact ion pairs and aggregate dominated interfacial solvation structures, boosting Zn²⁺ diffusion and deposition kinetics. Consequently, suppressed side reactions and homogenous (002)-crystal-preferred Zn²⁺ deposition can be simultaneously achieved. Therefore, an excellent cycling lifespan of 2500 h was obtained for the symmetric Zn cell and an ultra-stable cycling lifespan of 28 000 cycles for full cells. We believe that this catalytic desolvation strategy will pave a new avenue in the interfacial design of Zn anodes.