Ferroelectric small molecule enabled high-performance zinc-ion batteries

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 <i>versus</i> Zn/Zn²⁺. This interfacial restructuring also facilitates the <i>in situ</i> 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.