A thiol-modified solid electrolyte interphase enhances the stability of zinc anodes under high depths of discharge

Abstract

Aqueous zinc-ion batteries (AZIBs) have gained considerable attention within the growing energy storage sector. However, dendritic growth and side reactions on zinc anodes significantly degrade battery stability, especially at high depths of discharge (DODs). These issues present a substantial challenge in attaining long-term cycling performance. In this study, a new electrolyte additive, tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate (TMPEI), was employed to optimize the interface between the zinc electrode and electrolyte, effectively addressing these issues. The thiol groups in TMPEI strongly interact with zinc metal, forming stable Zn–S bonds through coordination interactions. This interaction results in the formation of a reliable and durable solid electrolyte interphase (SEI) layer on the zinc surface. This SEI layer not only controls zinc-ion deposition and inhibits dendrite growth but also decreases the energy barrier for zinc deposition. Furthermore, the hydrophobic properties of TMPEI help repel water molecules from the zinc anode, significantly limiting the hydrogen evolution reaction (HER) and corrosion processes. This effective interfacial protection enables Zn‖Zn symmetric cells to achieve stable cycling for up to 2000 h at 5 mA cm⁻² and 5 mA h cm⁻². Even under a high current density of 10 mA cm⁻² and a high DOD of 56.93%, the battery still demonstrates a cycling lifespan of 500 h. This research provides an efficient design strategy to enhance the cycling stability of zinc anodes in AZIBs under extreme conditions.