Intermolecular interaction promoted polymer cathode for ultrahigh capacity utilization and ultrafast ion diffusion of sodium metal battery

Although polymerization is an effective method to limit the dissolution of organic electrode materials, it is still a challenge to fully release their theory capacity because of less exposure of the active site due to the severe aggregation. Herein, a high capacity -utilization -rate polymer (poly-(tetraminobenzoquinone-alt-2,5-dihydroxy-1,4benzoquinone, PBQ) with strong intermolecular interactions is designed and synthesized. The theoretical calculations and experimental characterizations confirm that the intermolecular interactions including N-H & sdot;& sdot;& sdot; O hydrogen bonds and pi - pi interaction, endowing the PBQ with a regularly arranged plane structure. The fully exposed active site (C=O and C=N) enables PBQ cathode to achieve 99.8 % theoretical discharging capacity at 0.1 A g -1 (252.2 mAh g -1 for real capacity vs. 256.2 mAh g -1 for theoretical capacity). Additionally, PBQ cathodes display high cycling stability (98.6 % at 1 A g -1 after 400 cycles), a high discharge specific capacity of 236.1 mAh g -1 at -20 degree celsius, and a high ion diffusion coefficient around 1.9 x 10 -8 cm 2 s - 1 . This strategy realizes a breakthrough in maximizing the discharge specific capacity and provides new insights into ultrahigh practical capacity polymer designing.