High-Cycling Performance of Viologen-Based Conjugated Ionic Porous Organic Polymer Anode for Li-Ion Batteries

Compounds based on viologen are of great interest as anodes in lithium-ion batteries (LIBs) due to their π-conjugated aromatic structures, abundant active sites that promote stronger redox activity, and excellent structural tunability. In this study, two novel conjugated porous organic polymers, BIP-TAA and DPT-TAA, are synthesized via the Zincke reaction using different viologen structures as monomers. The electrochemical performance of BIP-TAA and DPT-TAA as anodes in lithium-ion batteries is then investigated. Compared to BIP-TAA, DPT-TAA demonstrates superior electrochemical performance, including higher electrical conductivity and enhanced redox activity, owing to the introduction of the bithiazole ring that extends the π-conjugated structure. Specifically, at a high current density of 2000 mA g^-1, DPT-TAA delivers a capacity of 113.67 mAh g^-1, immediately highlighting its advantages. More importantly, prolonged cycling at an identical rate increases the specific capacity of DPT-TAA from 124.26 to 321.1 mAh g^-1, significantly outperforming BIP-TAA (104.25 to 186.5 mAh g^-1). This performance unequivocally validates that the rigid, conjugated structure of DPT-TAA is pivotal for achieving outstanding cycling stability and capacity retention. Overall, DPT-TAA outperforms the basic viologen polymer in terms of cycling stability and multiplicity performance, providing a promising direction for the development of high-performance organic anode materials.