Monolayer Thiol Engineered Covalent Interface toward Stable Zinc Metal Anode

Interface engineering of zinc metal anodes is a promising remedy to relieve their inferior stability caused by dendrite growth and side reactions. Nevertheless, the low affinity and additional weight of the protective coating remain obstacles to their further implementation. Here, aroused by DFT simulation, self-assembled monolayers (SAMs) are selectively constructed to enhance the stability of zinc metal anodes in dilute aqueous electrolytes. It is found that the monolayer thiol molecules relatively prefer to selectively graft onto the unstable zinc crystal facets through strong Zn-S chemical interactions to engineer a covalent interface, enabling the uniform deposition of Zn2+ onto (002) crystal facets. Therefore, dendrite-free anodes with suppressed side reactions can be achieved, proven by in situ optical visualization and differential electrochemical mass spectrometry (DEMS). In particular, the thiol endows the symmetric cells with a 4000 h ultrastable plating/stripping at a specific current density of 1.0 mA cm-2, much superior to those of bare zinc anodes. Additionally, the full battery of modified anodes enables stable cycling of 87.2% capacity retention after 3300 cycles. By selectively capping unstable crystal facets with inert molecules, this work provides a promising design strategy at the molecular level for stable metal anodes.

Automated summary

This study demonstrates the enhancement of stability for zinc metal anodes by constructing self-assembled monolayers (SAMs) on their surfaces. By selectively grafting thiol molecules onto unstable zinc crystal facets, a covalent interface can be engineered to enable uniform zinc deposition and prevent dendrite growth and side reactions. The modified anodes exhibit improved electrochemical performance and cycling stability.