Multiple Redox-Active Cyano-Substituted Organic Compound Integrated with MXene Nanosheets for High-Performance Flexible Aqueous Zn-Ion Battery

An eco-friendly organic compound, with rich redox sites, considered a promising cathode material for aqueous zinc-ion batteries (AZIBs). Despite its potential, limited specific capacity and cycle instability impede its practical application. Herein, an organic compound, hexaazatriphenylene hexacarbonitrile (6CN-HAT), is designed with a pi-pi conjugated aromatic structure, and integrated with MXene nanosheets to construct a flexible self-supporting electrode (6CN-HAT@MXene). Ex-situ characterizations and theoretical calculations verify that the charge storage mechanism predominantly involves coordination and non-coordination reactions between reactive CN and CN sites with cations. The introduction of MXene nanosheets not only bolster the stability and electronic conductivity of the 6CN-HAT@MXene but also expose additional active sites for cation coordination. As a cathode material in AZIBs, 6CN-HAT@MXene exhibits an outstanding discharge specific capacity of 413 mAh g-1 at 0.05 A g-1. Remarkably, even after 5000 cycles at 5 A g-1, the discharge capacity retained 91%. Furthermore, based on the 6CN-HAT@MXene electrode, a flexible micro-zinc-ion batteries with high area capacity of 257.4 mF cm-2 is prepared using laser cutting technology, highlighting its potential for future applications in portable and wearable electronic devices. An organic compound with pi-pi conjugated aromatic structure of 6CN-HAT, and further integrated it with MXene nanosheets, creating a flexible self-supporting composite film 6CN-HAT@MXene for AZIBs. It exhibits an outstanding discharge capacity of 413.4 m Ah g-1 at 0.05 A g-1, and even after 5000 cycles at a current density of 5 A g-1, the discharge capacity remains at 91%. image