Benzoquinone-Based Polyimide Derivatives as High-Capacity and Stable Organic Cathodes for Lithium-Ion Batteries

Multicarbonyl polyimide derivatives were synthesized by a facial condensation polymerization of dianhydrides with a new diamine monomer containing a benzoquinone unit that was prepared according to the Michael addition reaction. The ingenious combination of dedicated carbonyl groups from the benzoquinone and dianhydride with an aniline structure linkage not only provided stable polymeric chains with a high number of carbonyl groups per unit but also guaranteed their large π-conjugated main chains, which is favorable to their long cycle life and fast kinetics. When explored as cathode materials for lithium-ion batteries, the polyimide derivatives based on naphthalic dianhydride delivered a reversible specific capacity of 145 mAh/g at 0.1 C, a high rate performance with a capacity of 108 mAh/g at 1 C, and an ultralong stable cyclic performance with a capacity retention of 80.3% after 1000 cycles at 0.5 C. Based on the theoretical calculations and the exploration of the electrochemical behaviors, sensible predictions for the reversible ion-insertion reaction of the as-prepared sample were proposed to deeply understand the charge storage mechanisms. Moreover, a stable solid electrolyte interphase film formed in the ether-based electrolyte was confirmed to improve the electrochemical properties.