Bio-inspired non-conjugated poly(carbonylpyridinium) as anode material for high-performance alkali-ion (Li, Na, and K) batteries.

The integration of multiple electron-accepting skeletons into polymeric structures is the forefront of materials research for high-energy sustainable energy storage. Herein, we report the synthesis of two novel non-conjugated polymers (NCP1 and NCP2) and a model small molecule (M1) incorporated with bio-derived 4-elecron-uptaking carbonylpyridinium redox-units for alkali-ion batteries. Compared to model small molecules, the polymers exhibited improved battery performance when applied as anode materials for Li-, Na-, and K-ion batteries (LIBs/SIBs/KIBs) owing to their high electrochemical activity and effective ability to suppress dissolution. By judicious selection of the benzothiadiazole redox-active linker, the performance of NCP2 was further enhanced, delivering the highest capacity and the best cycling stability; at mass loadings of up to 3.5 and 4.7 mg cm, the specific capacity remained at 215 and 150 mAh g after 200 cycles, respectively. The Li/Na/K insertion/extraction mechanisms of NCP2 were elucidated based on experimental analyses. The insertion/extraction of Li was much faster than that of Na and K. This study broadens the family of bio-derived carbonylpyridinium-based polymer materials for next-generation electrochemical energy storage applications.