Mechanism for Zincophilic Sites on Zinc-Metal Anode Hosts in Aqueous Batteries

摘要

The zinc-metal anode (ZMA) is a critical component of rechargeable Zn-based batteries. Zinc-dendrite formation on ZMA during cycling causes an internal short-circuit, thereby limiting long-term practical operation of batteries. A strategy of introducing zincophilic sites shows promise in suppressing dendrite growth. However, the mechanism is not understood. Here, a detailed study of the mechanism of zincophilic sites based on multiple in situ/ex situ techniques is reported. Using a carbon-host as a model system with nitrogen sites as zincophilic sites and both ex situ near-edge X-ray absorption fine structure (NEXAFS) and in situ Raman spectra, it is shown that zinc ions are bonded with pyridine sites to form Zn-N bonds. The Zn-N bonds induce spacious nucleation of zinc on carbon-hosts and suppress zinc-dendrite formation. The host with zincophilic sites exhibits a homogenous Zn deposition, together with boosted electrochemical performance. This finding underscores the impact of nitrogen zincophilic sites in suppressing zinc-dendrite formation. It is shown that bonding between zinc ions and zincophilic sites is the mechanism for zincophilic nucleation in the ZMA host. These findings are expected to be of immediate benefit to researchers in battery technologies and materials science.