In-situ electropolymerization of bipolar organic cathodes for highly efficient Li-ion batteries

Organic cathodes face the challenge of dissolution problem, which severely hinders their electrochemical performances in lithium-ion batteries (LIBs). Herein, a bipolar organic cathode namely [ N , N ′-bis(4-(9H-carbazol-9-yl)phenyl)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DPC, 4-electron C T  = 123 mAh g −1 ) is optimized by in-situ electropolymerization to eliminate its dissolution problem, and thus the good cathode performance of the electropolymerized PTCDI-DPC can be fully released in LIBs. In half cells, PTCDI-DPC delivers a peak specific capacity of 164 mAh g −1 and the good retention of 96 % over 450 cycles. Meanwhile, PTCDI-DPC still remains 121 mAh g −1 after 2000 cycles at 1 A g −1 , and a superior rate performance of 98 mAh g −1 at 8 A g −1 . Furthermore, the fabricated 2PF 6 -PTCDI-DPC||LiC 6 Li-ion full cells can possess the peak discharge capacity of 157 mAh g −1 cathode and a high energy density of 385 Wh kg −1 cathode in 1.4–4.3 V, with 90 % capacity retention during 2000 cycles at 1 A g −1 . As far as we know, the cathode performance of the improved PTCDI-DPC is one of the best among bipolar organic cathodes reported for LIBs.