Thiazole‐Linked Covalent Organic Framework Promoting Fast Two‐Electron Transfer for Lithium‐Organic Batteries

• Published in: Advanced energy materials Vol. 11; no. 17
• Main Authors: Singh, Vikram, Kim, Jaewook, Kang, Bora, Moon, Joonhee, Kim, Sujung, Kim, Woo Youn, Byon, Hye Ryung
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.05.2021
• Subjects: azo; covalent organic framework; Electrical resistivity; Electrodes; Electron transfer; imine; Lithium; lithium‐ion battery; organic electrode; Redox reactions; Structural stability; thiazole; β‐ketoenamine
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202003735

Covalent organic frameworks (COFs) have been considered a potentially versatile electrode structure if they are made highly conductive and flexible to stabilize the redox functionality. Although conceptually plausible, COF‐based electrodes have rarely satisfied high capacity, cyclability, and rate capability thus far. Incorporating thiazole moieties into the organic scaffold, it is able to fabricate π‐conjugated and crystalline organic electrodes and demonstrate the fast two‐electron transfer in one step using azo functionality. The thiazole‐linked COF electrode performed over 5000 cycles at 10 C and a high power density of ≈2800 W kg−1 is achieved thanks to excellent chemical stability and high out‐of‐plane electrical conductivity. For comparison, COFs carrying β‐ketoenamine and imine linkers underperform due to the lack of structural stability. In this study, it is demonstrated that the design of linkages in the COFs is key to stabilize the redox reaction and show the basic principles of building COF electrodes for high‐performance lithium‐organic batteries. A linkage‐driven strategy is developed to tune the redox‐activity of azo‐interlocked covalent organic frameworks (COFs) in Li‐organic batteries. Thiazole linkage stabilizes the lithiated and delithiated azo group in the COF backbone as revealed by experimental, computational, and operando investigations. Higher out‐of‐plane conductivity and enhanced structural stability during cycling in thiazole‐linked azo‐COF afford higher power density and long cycle life.