Weaving electron-rich alkynes: a durable in situ skin for stabilizing zinc anodes

Abstract

The labile reactivity at the electric double layer (EDL) causes instability of the metallic anode in aqueous zinc batteries (AZBs). To address this issue, an electron-rich thiophdiyne interphase (e-TDYP) is in situ engineered as a durable “coordination skin” to stabilize the EDL of zinc anodes. The high electron density of e-TDYP facilitates strong interactions with zinc ions, enabling efficient zinc ion transport and deposition at the anode surface. The conjugated thiophene and cyclic diyne groups of e-TDYP reconstruct the EDL, while maintaining structural integrity and properties during long-term cycling. By leveraging the dynamic responsiveness of thiophene groups and alkyne bonds, the e-TDYP modified zinc anode achieves a low polarization voltage and long-term reversible plating/stripping over 1000 hours at 5 mA cm⁻²/5 mA h cm⁻² with a high depth of discharge (DOD). Density functional theory (DFT) calculations indicate that Zn ions preferentially navigate the migration pathway via the cyclic diyne center's anchoring site with a low energy barrier. Full cell tests further demonstrate impressive capacity retention after 6000 cycles at 2 A g⁻¹. These findings underscore the importance of advanced electrode design through EDL regulation, which allows for achieving stable zinc anodes.