A Nitrogen-Rich 2D sp² Carbon-Linked Conjugated Polymer Framework as a High-Performance Cathode for Lithium-ion Batteries.

In this work, we report a novel two-dimensional (2D) sp² carbon-linked conjugated polymer framework (2D CCP-HATN) with a nitrogen-doped skeleton, a periodical dual-pore structure and high chemical stability. The chemical identity of the polymer backbone consisting of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon-carbon double bonds is verified by FT-IR, Raman and solid-state 13C cross-polarization magic-angle spinning (CP-MAS) NMR spectroscopies. In stacked form, together with the imine-linked covalent organic framework analogue 2D C=N HATN, the interior framework architecture of the crystalline 2D CCP-HATN is unambiguously demonstrated by powder X-ray diffraction and N2 adsorption-desorption measurements. Profiting from the shape-persistent framework of 2D CCP-HATN integrated with the electrochemical redox-active HATN and the robust sp2 carbon-carbon linkage, 2D CCP-HATN hybridized with carbon nanotubes shows an excellent capacity of 116 mA h/g, with high utilization of its redox-active sites and superb cycling stability (91% after 1000 cycles) and rate capability (82%, 1.0 A/g vs 0.1 A/g) as an organic cathode material for lithium-ion batteries.