Boosting lithium ions inserting onto aromatic ring by extending conjugation of triazine-based porous organic frameworks for lithium-ion batteries

Conjugated polymeric materials characterized by chemical cost benefit, environmental friendliness and richness at the molecular design, are considered as promising electrode materials for LIBs. However, their relatively low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles and deep exploration of their electrochemical mechanisms are also urgently needed. Here, two triazine-based porous polymeric frameworks with tunable conjugated structures are fabricated and their electrochemical behaviors are explored in-depth to further probe the mechanisms of lithium ions inserting onto aromatic rings. Based on the ex-situ experimental analysis and theoretical calculations, the intercalation of lithium ions is a stepwise process for triazine and benzene units, and the polymer with extended conjugation structures could involve 12 lithium ions intercalation with a high capacity of 1497.6 mAh g-1 after 150 cycles at 100 mA g−1. Furthermore, the full cells also elicit the potential of the ToF-2 as a readily processable anode material with the commercially tested LiCoO2 as cathode.