Single organic electrode for multi-system dual-ion symmetric batteries

The large void space of organic electrodes endows themselves with the capability to store different counter ions without size concern. In this work, a small-molecule organic bipolar electrode called diquinoxalino[2,3-a:2',3'-c]phenazine-2,6,10-tris(phenoxazine) (DQPZ-3PXZ) is designed. Based on its robust solid structure by the π conjugation of diquinoxalino[2,3-a:2',3'-c]phenazine (DQPZ) and phenoxazine (PXZ), DQPZ-3PXZ can indiscriminately and stably host 5 counter ions with different charge and size (Li⁺, Na⁺, K⁺, PF₆^- and FSI^-). In Li/Na/K-based half cells, DQPZ-3PXZ can deliver the peak discharge capacities of 257/243/253 mAh g^-1_cathode and peak energy densities of 609/530/572 Wh kg^-1_cathode, respectively. The Li/Na/K-based dual-ion symmetric batteries can be constructed, which can be activated through the 1st charge process and show the stable discharge capacities of 85/66/72 mAh g^-1_cathode and energy densities of 59/50/52 Wh kg^-1_{total mass}, all running for more than 15000 cycles with nearly 100% capacity retention.