Constructing fast ion-transport channels for reversible zinc metal anodes enabled by self-concentration effect

Abstract

The zinc (Zn) metal batteries suffer from poor plating/stripping behaviors due to the severe dendrite growth and side reactions stemming from the sluggish ion migration at the electrolyte/electrode interface. Despite effectiveness by constructing artificial ion-diffusion layer to alleviate these issues, the intrinsic mechanism of zinc ion (Zn2+) diffusion within the interfacial layer is not well elucidated yet. Here, inspired by the ability of vermiculite (VRM) to promote the self-concentration kinetics of metal ions, this intrinsic issue can be tackled by elaborately constructing VRM with fast ion-transport channels on the surface of Zn metal anodes. This unique ion channel with a natural negatively charged wall can accelerate Zn2+ transport and reduce the presence of water molecules in Zn2+ solvated shell, which can be demonstrated by molecular dynamic simulation. As a proof of concept, the symmetric cell with VRM@Zn anode achieves dendrite-free plating/stripping with a stable cycling life (580 h) even at a high rate of 25 mA cm−2 with a capacity of 12.5 mAh cm−2. Meanwhile, the Zn-carbon supercapacitor with VRM@Zn anode exhibits an extended stability over 5000 cycles at 1 A g−1. This work reveals the internal mechanism of Zn2+ diffusion within the interfacial layer, and provides an avenue for constructing highly reversible Zn metal anode.