Asymmetric Zn-N4 atomic sites embedded hollow fibers as stable Zn anode for high-performance Zn-ion hybrid capacitor

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Zn based electrochemical energy storage systems (EES) have attracted tremendous interests owing to their low cost and high intrinsic safety. Nevertheless, the uncontrolled growth of Zn dendrites and the side reactions of Zn metal anodes (ZMAs) severely restrict their applications. To address these issues, we design the asymmetric Zn-N4 atomic sites embedded hollow fibers (AS-IHF) as the flexible host for stable ZMAs. Through introducing different nitrogen resources in the synthesis, two kinds of coordination, i. e. Zn-N (pyridinic) and Zn-N (pyrrolic), are introduced in the Zn-N4 atomic module synchronously. The asymmetric Zn-N4 module with regulated micro-environment facilitates the superior zincophilic features and promotes the Zn adsorption. Meanwhile, the highly porous structure of the hollow fiber effectively reduces local current density, homogenize Zn ion flux, and alleviate structure stress. All the advantages endow the high efficiency and good stability for Zn plating/stripping. Both theoretical and experimental results demonstrate the high reversibility, low nucleation overpotential, and dendrite-free behavior of the AS-IHF@Zn anode, which afford the high stability in high-rate and long-term cycling. Moreover, the solid-state Zn-ion hybrid capacitor (ZIHC) based on AS-IHF@Zn anode shows the high flexibility, reliability, and superior long-term cycling capability in a wide-range of temperatures (−20–25 °C). Therefore, the present work not only gives a new strategy for modulating local environments of single atomic sites, but also propels the development of flexible power sources for diverse electronics.