A Perylene Diimide Crystal with High Capacity and Stable Cyclability for Na-Ion Batteries

Organic Na-host materials have are now actively pursued as an attractive alternative to conventional transition-metal compounds for development of sustainable sodium ion batteries; however, most of the organic compounds reported so far suffer from their low reversible capacity and poor cyclability. Here, we report a simple perylene diimide, 3,4,9,10-perylene-bis(dicarboximide) (PTCDI), which demonstrates remarkable electrochemical performances as an organic cathode for Na-ion batteries. With the high density of redox-active carbonyl groups in a stable π-conjugated structure, the PTCDI molecule can undergo a two-electron redox reaction with reversible insertion/extraction of 2 Na(+) ions per molecular unit, demonstrating a high capacity of 140 mAh g(-1), a strong rate performance with a reversible capacity of 103 mAh g(-1) at 600 mA g(-1) (5 C,1 C = 120 mA g(-1)) and a long-term cyclability with 90% capacity retention over 300 cycles. Because this PTCDI material is commercially available and nontoxic, it may serve as a new alternative cathode for Na-ion battery applications.