Protonated alkynyl-linked bipolar conjugated microporous polymers as high-rate-capacity Lithium-ion battery cathodes

Conjugated microporous polymers (CMPs) have emerged as promising organic cathode materials for high-performance lithium-ion batteries (LIBs). Herein, we present a protonated π-extended alkynyl-linked bipolar CMP (P-TAPE) for high-rate-capacity LIB cathode. P-TAPE was synthesized via Buchwald-Hartwig coupling by adopting tris(4-aminophenyl)amine and bis(4-bromophenyl)acetylene as units, followed by post-protonation treatment. The π-extended alkynyl linker enhances π-delocalization and backbone rigidity while introducing additional Li-reactive sites for n-type charge storage. While protonation of the triphenylamine p-type sites induces electronic polarization and narrows the bandgap, furthering facilitating faster charge transfer. As expected, P-TAPE shows a higher conductivity of 2.08 × 10^-6 s m^-1 and delivers a high specific capacity of 310.9 mA h g^-1 (574.5 Wh kg^-1) at 100 mA g^-1, a high-rate-capacity of 186.1 mA h g^-1 at 10 A g^-1 and stable cycling performance (97% retention over 2000 cycles at 5 A g^-1). This work gives insights into developing high-rate-capacity organic cathodes by rational designing protonated bipolar CMP for next-generation energy storage systems.