Spatial Confinement and Induced Deposition of ZnHCF in 3D Structure for Ultrahigh-Rate and Dendrite-Free Zn Anodes.

Abstract

Aqueous Zn-metal batteries (AZBs) are thought as highly prospective candidates for large-scale energy-storage systems because of their abundant natural resources, low cost, high safety, and environmentally friendly. Nevertheless, the key problems of AZBs are the uncontrollable zinc dendrites growth and water-induced erosion faced by zinc anodes. Therefore, reducing the hydrophilicity of zinc anode and introducing the zincophilic sites are the availably strategy. Herein, 3D highly-conductive host is developed to inhibit Zn dendrites growth, which have a porous structure consisting of graphene and carbon nanotubes embedded with a zincophilic nucleation sites of Zn Prussian blue analogs (ZnHCF@3D-GC). The inner ZnHCF possess minimized nucleation barriers, which can serve as favorable nucleation sites, and 3D host provide a buffer interspace to allow for even more high-capacity Zn plating. Additionally, density functional theory results show that ZnHCF exhibits a strong Zn binding energy and high adsorption energy of Zn (002) plane, which can guide Zn horizontal deposition in the 3D host. As a result, the assembled symmetrical cell is able to stabilize 900 cycles at an ultrahigh current density of 100 mA cm^-2. Zn-ZnHCF@3D-GC//MnO₂ and Zn-ZnHCF@3D-GC//ZnHCF full cells can be stably cycled 1000 cycles at 2.0 A g^-1.