Superlithiation\nPerformance of Covalent Triazine Frameworks\nas Anodes in Lithium-Ion Batteries

Abstract

Organics\nwith the merit of renewability have been viewed as the\npromising alternative of inorganic electrode materials in lithium-ion\nbatteries, but most of them display inferior performance due to the\nsluggish ion/electron diffusion and the potential dissolution in aprotic\nelectrolytes. Here, covalent triazine frameworks (CTFs-1), full of\nvertical pores and layered spaces for Li⁺ transfer, have\nbeen synthesized with <i>p</i>-dicyanobenzene as the monomer\nby a facile two-step method including a prepolymerization with CF₃SO₃H as the catalyst and deep polymerization in\nmolten ZnCl₂. CTFs-1-400, obtained at the deep polymerization\ntemperature of 400 °C, exhibits the superlithiation property\nwith the specific capacities of 1626 mA h g^–1 at\n25 °C and 1913 mA h g^–1 at 45 °C at 100\nmA g^–1, indicating the formation of Li₆C₆/Li₆C₃N₃ in the reduction\nprocess. Electrochemical analysis and density functional theory calculation\nindicate that the ultrahigh capacity is mainly contributed by the\ncapacitance of micropores and the redox capacity of benzene and triazine\nrings. Moreover, CTFs-1-400 displays the specific capacity of 740\nmA h g^–1 for 1000 cycles at 1 A g^–1 with almost no capacity fading.