Synthesis of triazine-based covalent organic framework nanoparticles as cathode materials for lithium-sulfur batteries

Abstract

Covalent organic frameworks (COFs) hold promise as ideal sulfur carrier materials for lithium-sulfur battery cathodes due to their well-defined pore structures and abundant heteroatom sites. Incorporating sulfur into COFs to form S@COF composites can overcome the reaction kinetic barriers inherent in sulfur cathodes and suppress the occurrence of the shuttle effect. However, COFs obtained through traditional solvothermal strategies often exhibit severe stacking, adversely affecting the electrochemical activity of the electrode. In this work, to obtain highly dispersed COF materials, highly dispersed COF nanoparticles with diameters of only 15-30 nm were successfully synthesized at room temperature by introducing surfactants into the reaction system, named TpTapt-NP. Furthermore, sulfur was successfully incorporated into the pores of TpTapt-NP to produce 70S@TpTapt-NP. Battery performance test results showed that 70S@TpTapt-NP maintained a specific capacity of 447 mAh g⁻¹ at a current density of 3 C, demonstrating significantly improved rate performance compared to the 70S@TpTapt (283 mAh g⁻¹) obtained by the solvothermal strategy. Furthermore, the distribution of relaxation time analysis indicated that TpTapt-NP promoted the exposition of N and O active sites and reduced mass transfer barriers in the electrode reaction process. This provides insights for the preparation of novel S@COF cathode materials for lithium-sulfur batteries..