Extending π‐Conjugation and Integrating Multi‐Redox Centers into One Molecule for High‐Capacity Organic Cathodes

Abstract

Structural diversity, designability, and eco‐friendliness make organic electrode materials appealing for next‐generation rechargeable batteries. However, most of them show low specific capacity and poor cycling stability, which limit their further application. To develop high‐capacity imide‐based cathode materials, three C3‐symmetric triimides were designed. Systematic comparisons of these triimides as cathode materials revealed that extending π‐conjugation and incorporating multiple redox centers improved the cell performance in terms of specific capacity and cycling stability. In particular, a nitrogen‐rich heteroaromatic hexaazatrinaphthylene triimide (HATNTI‐Pr) with multiple active sites (imide and pyrazine) exhibited high specific capacity. Hybridized with graphene sheets, a HATNTI‐Pr‐based binder‐free cathode delivered a high practical capacity (317 mAh g−1 at 0.1 C), excellent cycling stability (80 % retention after 100 cycles), and considerable rate performance (75 mAh g−1 at 5 C). The energy storage mechanism of HATNTI‐Pr with up to nine Li+ storage ability was investigated.

Constructing Extended π-Conjugated Molecules with o-Quinone Groups as High-Energy Organic Cathode Materials

“…In the FTIR spectra (Figure b), during the discharge process, the CO peak at 1700 cm –1 disappeared (it probably red-shifted and became overlapped with other peaks), while the CC peak at 1591 cm –1 and CN peak at 1534 cm –1 red-shifted by 19 and 34 cm –1 , respectively. Meanwhile, the N···Li peak at 1438 cm –1 and O···Li peak at 1382 cm –1 appeared and were gradually enhanced. − These variations agreed well with the synergetic reduction of quinone (CO) and pyrazine (CN) in the discharge process. In the subsequent charge process, the variations completely reversed, indicating the high redox reversibility.…”

Covalent organic frameworks as electrode materials for rechargeable metal‐ion batteries

“…[34,54] In addition, triquinoxalinylene has attracted increasing attention due to its multiple C=N redox sites, which can react with six Li + and offer a high capacity. [55][56][57][58][59] Moreover, the N-rich and expanded conjugated structure is conducive to enhance rate performance. Besides, the conjugated C=N linkages, formed by Schiff base reactions between -NH 2 and -CHO, can also be used as redox sites in some cases.…”

Building a high-performance organic cathode material containing electron-withdrawing groups for lithium-ion batteries

“…PPh-PTO 220 mAh g -1 at 0.4 C 1.5-3.8 [14] HATNTI-Pr 293 mAh g -1 at 0.1 C 1.2-3.8 [17] HATN-AQ-COF 319 mAh g -1 at 0.5 C 1.2-3.9 [33] 3-DTBPT 110 mAh g -1 at 0.05 A g -1 1.5-4.0 [34] PEDOT/PDBM 129 mAh g -1 at 0.05 C 2.0-4.0 [35] PTCDA 180 mAh g -1 at 0.025A g -1 1.5-4.6 [36] Li/PTMA 110 mAh g -1 at 1 C 2.6-4.5 [37] PHP 128 mAh g -1 at 0.05 C 2.0-3.0 [38] AP 160 mAh g -1 at 0.05 C 2.0-3.0 [38] PRP 172 mAh g -1 at 0.05 C 2.0-3.0 [38] Indigo carmine 110 mAh g -1 at 0.01 A g -1 1.5-3.0 [39] CL-DVP-NDI 121.3 mAh g -1 at 0.2 C 1.5-3.0 [40] TNHATN 361.7 mAh g -1 at 0.05 A g -¹ 1.3-4.0 This work…”

“…[8] Because organic electrode materials are readily available, and have the advantages of environmental friendliness and designable structure, they have been widely investigated as cathode materials for LIBs and considered as the candidates of metal oxides. [9][10][11][12][13][14][15][16][17] Although a great deal of progress has been made in this field, how to obtain high-performance organic cathode materials for LIBs is still an important task. Theoretically, organic molecule with multi-electron transfer ability as the active substance will be favor to enhance the specific capacitance of organic electrode.…”