Electrochemical lithium storage of a biactive organic molecule containing cyano and imine groups

Abstract

With an electron-deficient rigid planar structure and excellent π–π stacking ability, hexaazatriphenylene (HAT) and its derivatives are widely used as basic building blocks for constructing covalent organic frameworks (COFs), components of organic light-emitting diodes and solar cells, and electrode materials for lithium-ion batteries (LIBs). Here, a HAT derivative, hexaazatriphenylenehexacarbonitrile, is explored as an anode material for LIBs. The HAT anode exhibited high initial reversible capacities of 672 mA h g⁻¹ at 100 mA g⁻¹ and 550 mA h g⁻¹ at 400 mA g⁻¹ and stable cycling with a capacity of 503 mA h g⁻¹ after 1000 cycles at 400 mA g⁻¹ corresponding to a capacity retention of 91.5%. Furthermore, the lithium storage mechanism and the cause of the first irreversible capacity loss of the HAT anode were investigated by X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations. We have carried out a series of analyses on the mechanism of initial capacity loss. This study provides new insight on initial capacity loss and provides valuable insights into the molecular design and the electrochemical properties of HAT-based anode materials.