Lin Zirui, Lin Lu, Zhu Jiaqi, Wu Wanlong, Yang Xianpeng, Sun Xiaoqi
Department of Chemistry, Northeastern University, 3-11 Wenhua Road, Shenyang 110819, China.
ACS Appl Mater Interfaces. 2022 Aug 31;14(34):38689-38695. doi: 10.1021/acsami.2c08170. Epub 2022 Aug 17.
Covalent organic frameworks (COFs) are promising cathode candidates with high structural stability. However, they contain redox inactive linkages and experience low redox potential. Herein, a full anti-aromatic microporous COF cathode material of TAQ-BQ is designed for aqueous zinc batteries. The anti-aromatic conjugation effectively lowers the energy level of the lowest unoccupied molecular orbital as revealed by theoretical calculations, which corresponds to an elevated redox potential. Besides, the structure contains imino active sites at the linkages, in addition to carbonyl at the active parts. As a result, the TAQ-BQ cathode exhibits a voltage of 1.53 V/1.54 V and between 1.35 and 0.45 V in zinc cells. It delivers 208 mAh g capacity at 0.1 A g and maintains 136 mAh g at 2 A g. Stable cycling is realized for 1000 cycles with 87% capacity retention. The co-de/insertion of Zn and protons is identified for energy storage. Our work reveals the promises of COF cathode materials for aqueous zinc batteries.
共价有机框架（COFs）是具有高结构稳定性的、很有前景的阴极候选材料。然而，它们含有氧化还原惰性键，且氧化还原电位较低。在此，设计了一种用于水系锌电池的全反芳香族微孔COF阴极材料TAQ-BQ。理论计算表明，反芳香族共轭有效地降低了最低未占据分子轨道的能级，这对应于更高的氧化还原电位。此外，该结构在连接部位含有亚氨基活性位点，活性部分还含有羰基。结果，TAQ-BQ阴极在锌电池中的电压为1.53 V/1.54 V，在1.35 V至0.45 V之间。它在0.1 A g下的容量为208 mAh g，在2 A g下保持136 mAh g。实现了1000次循环的稳定循环，容量保持率为87%。确定了锌和质子的共脱嵌用于能量存储。我们的工作揭示了COF阴极材料用于水系锌电池的前景。
