Non-conjugated diketone as a linkage for enhancing the rate performance of poly(perylenediimides)

Abstract

The electrochemically active carbonyl groups in cyclized diketones or conjugated carboxylates have been widely studied as electrode materials. But the effects of non-conjugated carbonyl groups on the electrochemical properties have been overlooked. This contribution studies the effects of non-conjugated carbonyl groups on perylenediimide (PDI)-based polyimides (poly(PDI)s) as a proof-of-concept. The results show that non-conjugated diketone as a linkage can enhance the rate performance and cyclability of poly(perylene diimide)s: a capacity of 120.9 mA h g⁻¹ at 2 A g⁻¹ after 1000 cycles with a decay rate of 0.0039 mA h g⁻¹ per cycle can be obtained, which is among the best performance of polyimide-based electrodes. The experiments and simulations prove that the diketone groups in the linkage facilitate the adsorption and diffusion of Na⁺, which contribute to the outstanding rate performance. Therefore, our work highlights the importance of non-conjugated diketone groups as the linkage for enhancing the rate performance of sodium-ion batteries.