A Sulfur Heterocyclic Quinone Cathode and a Multifunctional Binder for a High‐Performance Rechargeable Lithium‐Ion Battery

We report a rational design of a sulfur heterocyclic quinone (dibenzo[b,i]thianthrene-5,7,12,14-tetraone=DTT) used as a cathode (uptake of four lithium ions to form Li4 DTT) and a conductive polymer [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)=PSS) used as a binder for a high-performance rechargeable lithium-ion battery. Because of the reduced energy level of the lowest unoccupied molecular orbital (LUMO) caused by the introduced S atoms, the initial Li-ion intercalation potential of DTT is 2.89 V, which is 0.3 V higher than that of its carbon analog. Meanwhile, there is a noncovalent interaction between DTT andPSS, which remarkably suppressed the dissolution and enhanced the conductivity of DTT, thus leading to the great improvement of the electrochemical performance. The DTT cathode with thePSS binder displays a long-term cycling stability (292 mAh g(-1) for the first cycle, 266 mAh g(-1) after 200 cycles at 0.1 C) and a high rate capability (220 mAh g(-1) at 1 C). This design strategy based on a noncovalent interaction is very effective for the application of small organic molecules as the cathode of rechargeable lithium-ion batteries.