Organic Nanosheets of Imide-Linked Cathodes for High-Performance Aqueous Zinc-Ion Batteries

Organicelectrodes have been identified as promising energy-storagematerials for aqueous zinc-ion batteries (AZIBs). Small molecularmaterials have ideal redox properties, high specific capacity, andstructural diversity, making them a category of cathode candidatesfor AZIBs. However, the instability and dissolution during the extractionand insertion of H+/Zn2+ limit their applicationof the long-cycle stability for AZIBs. Herein, a small-molecule nanosheet(NI-DAQ, & SIM;14 nm in thickness) with imide linkage is designedand synthesized by the condensation of anthraquinones and anhydrides.It not only inhibits the dissolution of monomer electrodes but alsoboosts the reactivity and conductivity of the whole molecule by theintroduction of & pi;-conjugated imide groups and extended aromaticplanes. Therefore, the NI-DAQ electrode obtains a large initial capacityof 191.9 mA h g(-1) at 50 mA g(-1) and superior cyclability after 3000 cycles at 500 mA g(-1) with a minor average capacity fading rate of 0.01% per cycle. Moreover,in situ Fourier transform infrared (FT-IR) and ex situ X-ray photoelectronspectroscopy (XPS) characterization techniques have been implementedto investigate the redox mechanism of C O units in AZIBs forthe NI-DAQ electrode. Thus, a promising conductive molecule is developedand explored in this paper, which can provide insights into the applicationof organic materials in AZIBs.

Automated summary

In this study, a small-molecule nanosheet (NI-DAQ) was designed and synthesized to inhibit the dissolution of monomer electrodes and enhance the reactivity and conductivity of the whole molecule. NI-DAQ electrode exhibited a large initial capacity of 191.9 mA h g(-1) at 50 mA g(-1) and superior cyclability after 3000 cycles at 500 mA g(-1) with a minor average capacity fading rate of 0.01% per cycle. The redox mechanism of C=O units in AZIBs for the NI-DAQ electrode was investigated using in situ Fourier transform infrared (FT-IR) and ex situ X-ray photoelectron spectroscopy (XPS) characterization techniques.