Insoluble small-molecule organic cathodes for highly efficient pure-organic Li-ion batteries

An insoluble small-molecule organic compound [N,N′-bis(2-anthraquinone)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DAQ) can be a high-performance cathode in Li-ion batteries (LIBs). In half cells, PTCDI-DAQ delivers a peak specific capacity of 229 mA h g−1, along with the good retention of 82% over 3 months. Meanwhile, PTCDI-DAQ can still hold a capacity of 46 mA h g−1 at 25 A g−1. By using the reduced state (Li4TP) of lithium terephthalate (Li2TP) as an organic anode in the all-organic Li-ion batteries (OLIBs), our OLIBs can realize a high-energy density of 296 W h kg−1cathode in the voltage range of 0.2–3.2 V and fulfill a long lifespan over 20 000 cycles. To the best of our knowledge, the comprehensive performance of our PTCDI-DAQ II Li4TP OLIBs is currently one of the best pure-organic LIBs in the world.