Donor dominated triazine-based microporous polymer as a polysulfide immobilizer and catalyst for high-performance lithium-sulfur batteries

Abstract Triazine-based framework is an attractive organic polymer with microporous structure and high nitrogen content that could retard the shuttle of polysulfides for high-performance lithium-sulfur (Li-S) batteries. However, insight into the role of π-conjugated donor of triazine-based polymer in immobilizing and catalytzing polysulfides is still deficient. Here, two homologous conjugated buildings of triazine unit combining with perylene (CTP-1) and spirobifluorene (CTP-2) were reasonably synthesized through one-pot Suzuki-Miyaura coupling reaction with a high yield of 92% and served as the polysulfides immobilizer and catalyst to achieve high-performance Li-S batteries. Compared with the counterpart of CTP-2, the fully conjugated CTP-1 modified separator possesses a higher ionic conductivity and Li+ transference number presenting more efficient shuttle inhibition and faster kinetics in catalyzing polysulfides conversion. Theoretical calculations demonstrate that the CTP-1 with perylene donor features narrower bandgap and faster electron transfer exhibiting stronger binding ability toward polysulfides than CTP-2. This work broadens the understanding of donor dominated chemical immobilizing and catalysis of triazine-based materials in Li-S batteries, and provides guidance for the future design of organic materials in other energy storage systems.