Unveiling interfacial electron-ion coupled dynamics in organic-inorganic composite materials for fast air self-charging zinc-ion batteries.

Abstract

Air self-charging aqueous zinc-ion batteries (AZIBs) have garnered significant attention for their integrated energy-harvesting and storage capabilities. However, their performance is often hindered by sluggish electrode reaction kinetics and restricted cation transport channels. Herein, an organic-inorganic composite cathode, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA)@VO₂, is constructed via a synergistic design strategy, in which NTCDA molecules uniformly coat and partially intercalate into the VO₂ layers, thereby optimizing electron transport and ion diffusion pathways. Compared with reported organic-inorganic composite cathodes that mainly rely on inorganic additives to improve conductivity or structural stability, NTCDA@VO₂ constructs an active organic-inorganic interface, in which VO₂ acts as an electron donor to regulate the electronic structure of NTCDA, while its layered framework enables the ordered distribution of NTCDA molecules. Benefiting from this structural synergy, the Zn//NTCDA@VO₂ battery exhibits an open-circuit voltage recovery to 1.21 V after 1 h of air exposure and delivers a high discharge capacity of 170.1 mAh g^-1 at 0.2 A g^-1. Experimental and theoretical analyses reveal that the carbonyl (C=O) groups serve as the main redox-active sites, participating in the cooperative insertion/extraction of Zn²⁺ and H⁺. Meanwhile, VO₂ acts as an electron donor when combined with NTCDA, promoting oxygen activation and reducing the oxygen reduction reaction (ORR) energy barrier from 0.91 to 0.39 eV, thereby accelerating charge transfer and ion migration. This work elucidates the electron-ion coupling mechanism at the organic-inorganic interface regulated by the inorganic framework, providing new insights for designing efficient air self-charging energy storage systems.