An electron-losing regulation strategy for stripping modulation towards a highly reversible Zn anode

Abstract

The practical application of aqueous zinc-ion batteries (AZIBs) is hindered by their low coulombic efficiency (CE) and unstable cycle life. Numerous electrolyte-additive-related studies have been performed, but most of the focus has been on the Zn plating process. In fact, practical AZIBs undergo stripping in practice rather than plating in the initial cycle, because the commonly used cathodes in the charged state do not have zinc ions, so a uniform stripping process is crucial for the cell performance of AZIBs. Here, we propose an electron-losing regulation strategy for stripping modulation by adding additives. Oxolane (OL) was chosen as the model additive to verify this assumption. It is found that OL adsorbs onto the uneven initial Zn surface and accelerates the dissolution of the Zn tips, thus providing a uniform Zn anode during the stripping process. The oxygen atoms in OL reduce the surface energy of Zn and promote the exposure of the Zn (002) surface during plating. Consequently, cells with the OL electrolyte additive maintained a long lifespan and showed superior reversibility with a high average CE. The findings of this work lead to a deep understanding of the underlying mechanism of Zn anode stripping and provide new guidance for designing electrolyte additives.