Superlithiation Performance of Covalent Triazine Frameworks as Anodes in Lithium-Ion Batteries

Organics with the merit of renewability have been viewed as the promising alternative of inorganic electrode materials in lithium-ion batteries, but most of them display inferior performance due to the sluggish ion/electron diffusion and the potential dissolution in aprotic electrolytes. Here, covalent triazine frameworks (CTFs-1), full of vertical pores and layered spaces for Li⁺ transfer, have been synthesized with p-dicyanobenzene as the monomer by a facile two-step method including a prepolymerization with CF₃SO₃H as the catalyst and deep polymerization in molten ZnCl₂. CTFs-1-400, obtained at the deep polymerization temperature of 400 °C, exhibits the superlithiation property with the specific capacities of 1626 mA h g^-1 at 25 °C and 1913 mA h g^-1 at 45 °C at 100 mA g^-1, indicating the formation of Li₆C₆/Li₆C₃N₃ in the reduction process. Electrochemical analysis and density functional theory calculation indicate that the ultrahigh capacity is mainly contributed by the capacitance of micropores and the redox capacity of benzene and triazine rings. Moreover, CTFs-1-400 displays the specific capacity of 740 mA h g^-1 for 1000 cycles at 1 A g^-1 with almost no capacity fading.