An Insoluble Anthraquinone Dimer with Near-Plane Structure as a Cathode Material for Lithium-Ion Batteries.

Conjugated carbonyl-based organic electrode materials for lithium-ion batteries have gained increasing interests owing to their many advantages such as resource abundance and sustainable development. However, serious dissolution in organic liquid electrolytes is often encountered, resulting in inferior electrochemical performance such as poor cycling stability. Herein, a new molecular design strategy was developed to address the dissolution issue of 9,10-anthraquinone (AQ). An AQ dimer with near-plane molecular structure, 1,4-bis(9,10-anthraquinonyl)benzene (BAQB), was facilely synthesized. The near-plane structure was proved by DFT calculations. It was found that the obtained BAQB was insoluble in ether electrolyte. Compared to AQ, BAQB displayed remarkably enhanced cycling stability. After 100 cycles at 0.2 C, a high capacity retention of 91.6 % was achieved (195 mAh g-1 ). BAQB also exhibited excellent rate performance (138 mAh g-1 at 10 C). The results demonstrate the effectiveness of the near-plane molecular design concept. This work provides a new idea for rational molecular design to inhibit the dissolution of conjugated carbonyl-based organic electrode materials.