Dielectric layer induces depolarization field and interfacial interaction evolution to stabilize Zn anode

Abstract

Aqueous Zn batteries represent a safe, economical, and green energy‑storage technology. However, their practical viability is compromised by anodic instability caused by dendrite growth and the hydrogen evolution reaction (HER). While employing a dielectric layer as an artificial interphase can mitigate these issues, the underlying mechanism remains unclear. Herein, using lead-free NaNbO3 (NNO) as a model dielectric layer, we demonstrate that it facilitates uniform Zn deposition and inhibits HER via the combined effects of depolarization field and interfacial interaction evolution. First, the NNO dielectric layer generates a depolarization field that opposes the external tip-enhanced field during Zn deposition, thereby neutralizing the tip effect and preventing dendrite formation. Second, strong dipole-ion interactions between NNO and Zn2+ decelerate charge transfer kinetics, postponing the onset of Sand's time. Third, the anchoring of interfacial water molecules via dipole-dipole interactions restricts their access to the Zn surface, effectively suppressing HER. However, excessive NNO thickness hinders Zn2+ mass transport, leading to interfacial ion depletion and consequent dendrite growth. Optimizing the dielectric layer thickness enables uniform Zn deposition and effective HER suppression, delivering long cycling life and high Coulombic efficiency. This dielectric regulation strategy contributes to the advancement of durable, resource-efficient, and eco-friendly aqueous energy storage systems.