Engineering ion-pumping solid electrolyte interphase for ultra-stable aqueous zinc-ion batteries under deep discharge conditions

Abstract

Meeting the global terawatt-scale energy demands necessitates innovative solutions to overcome the critical challenges facing aqueous Zn-ion batteries, particularly the poor reversibility and unstable plating/stripping of Zn anodes under high depths of discharge (DOD). In this work, we introduce a novel composite artificial solid-electrolyte interphase (SEI), termed P-G, which combines a poly(ether-block-amide) matrix with graphene oxide (GO). By leveraging the functional groups of the polymer (C=O, C–O–C) and the electronegativity of GO, the P-G SEI layer acts as a highly efficient Zn2+ ion pump, achieving a remarkable Zn2+ transfer number of 0.77 and fast ion transport kinetics. Comprehensive theoretical and experimental analyses demonstrate that the P-G SEI layer regulates Zn2+ coordination and forms rapid ion transport pathways, leading to a highly stable and reversible Zn anode. As a result, P-G@Zn symmetric cells achieve ultra-stable cycling for 6500 hours at 1 mA·cm-2 and a record-breaking lifespan exceeding 5000 hours at 54.7% DOD. Furthermore, a high-specific-energy P-G@Zn||I2 pouch cell delivers exceptional performance, retaining 82.8% capacity after 400 cycles with an N/P ratio of 2. This study offers a compelling framework for designing advanced composite SEI layer, paving the way for highly reversible Zn-ion batteries in practical energy storage applications.