Structural modification enhances the electrochemical performance for organic cathode materials

Organic materials have become a research hotspot in the field of secondary batteries because of their high specific capacity, flexible designability, and environmental friendliness. However, their high solubility in organic electrolytes is the primary reason that restricts their applications. Herein, the poly-carbonyl active sites material calix[4]quinone (C4Q) is used as a structural template to design a polar molecule: methoxy acetate acid calix[3] quinone (C3Q). As a cathode material in lithium-ion batteries (LIBs), C3Q transforms into C3Q-Li by the in-situ electrochemical reaction in the initial discharge. Since C3Q-Li expresses low solubility in the electrolyte, which endows better stability to the electrode. Moreover, the transition from C3Q to C3Q-Li will neither affect the conjugate structure nor reduce the electrode voltage. The LIBs show a superior cycling ability (160 mAh/g at 1C after 1000 cycles) and an excellent rate performance (120 mAh/g at 8C). The electrochemical properties of C3Q-Li are a great leap forward compared to C4Q. Our work demonstrates that rational molecular design is important for achieving high-performance rechargeable batteries.