A Truxenone‐based Covalent Organic Framework as an All‐Solid‐State Lithium‐Ion Battery Cathode with High Capacity

Abstract

All-solid-state lithium ion batteries (LIBs) are ideal for energy storage given their safety and long-term stability. However, there is a limited availability of viable electrode active materials. Herein, we report a truxenone-based covalent organic framework (COF-TRO) as cathode materials for allsolid-state LIBs. The high-density carbonyl groups combined with the ordered crystalline COF structure greatly facilitate lithium ion storage via reversible redox reactions. As a result, a high specific capacity of 268 mAh g À1 , almost 97.5 % of the calculated theoretical capacity was achieved. To the best of our knowledge, this is the highest capacity among all COF-based cathode materials for all-solid-state LIBs reported so far. Moreover, the excellent cycling stability (99.9 % capacity retention after 100 cycles at 0.1 C rate) shown by COF-TRO suggests such truxenone-based COFs have great potential in energy storage applications.

Covalent Organic Frameworks as Emerging Battery Materials

“…However, the carbonyl group can conjugate with the benzene rings on the skeleton to improve the utilization ratio, so that truxenone units can combine with 6 Li + ions [44] . In addition, at low current densities, the C=C functional group generates super‐lithification due to the conjugation effect of the electrode structure to form the active site of the C6−M6 (Li + or Na + ) structure, such as anhydride‐based COF and carbonyl‐based COF materials [41b] . Obviously, the chemical environment and steric hindrance of the local molecular structure also determine the utilization of the active sites.…”