Modulating interfacial Zn2+ deposition mode towards stable Zn anode via bimetallic co-doped coating

Abstract

Artificial coatings represent the promising means to address the interfacial issues of Zn anode, but it poses a significant challenge to their stability due to the fatigue and resulting cracking of coatings during repeated cycling. Here, a functional coating with the synergistic effect of bimetallic co-doping was developed, which changes the Zn²⁺ deposition mode to interlayer deposition in coating. The simultaneous doping of Cu²⁺ and In³⁺ reduces the pyrrolic N content and enhances the adsorption of Zn²⁺ in the active sites. Bimetallic co-doping results in an increase in specific surface area and a decrease in pore size, thus providing more active sites. As well as enhanced electrical conductivity, electrons can enter between the coatings, thus promoting redox reactions between the layers. Therefore, it endows surface coating with low polarization and stress buffering simultaneously, which avoids cracking and stripping of coatings during cycling. As a result, the cycle life of CuInZIF-8@Zn||CuInZIF-8@Zn symmetric cell exhibits more than 1200 h at 5 mA cm⁻² and 5 mAh cm⁻². The CuInZIF-8@Zn anode can match multiple types of cathodes and achieve excellent cycling stability; For instance, it can cycle stably for 3000 cycles when paired with vanadium-based cathode. This work provides a new perspective of artificial coatings towards highly stable Zn anode.