Ferroelectric small molecule enabled high-performance zinc-ion batteries†
Abstract
To address the challenges of zinc-anode corrosion, hydrogen evolution reactions and dendrite growth in aqueous zinc-ion batteries, we introduce tetraethylammonium perchlorate (TEACC) as ferroelectric small molecules additives in an aqueous electrolyte. The TEACC molecules partially replace water molecules in the Zn2+ solvation sheath and enrich the electrode/electrolyte interface with TEACC–OTf, creating a water-deficient inner Helmholtz plane. As a result, the activity of free water is suppressed and the hydrogen-evolution potential shifts from −0.124 V to −0.271 V versus Zn/Zn2+. This interfacial restructuring also facilitates the in situ formation of a stable solid electrolyte interphase (SEI) consisting of ZnCO3, ZnCl2 and ZnS compounds, promoting highly reversible Zn plating/stripping with the coulombic efficiency exceeding 99.5%. Furthermore, the inherent ferroelectric properties of TEACC generate localized electric fields that help homogenize the distribution of Zn2+ across the electrode surface. This effectively suppresses dendritic growth and reduces the Zn2+ nucleation overpotential by 35 mV. Electrochemical evaluation of full cells with Zn‖TBABr3 demonstrated impressive performance, with 92.94% capacity retention after 380 cycles at 1.25 A g−1 and excellent rate capability across current densities from 0.5 to 3 A g−1. The system's practical applicability was further validated through flexible pouch cell configurations, where two series-connected cells powered 32 commercial LED indicators, showcasing the potential of this approach for flexible energy storage devices. Overall, the findings not only present a promising strategy for stabilizing zinc anode interfaces but also highlight the potential of ferroelectric molecular additives in advanced aqueous battery systems.