Synthesis of cheese-shaped capacitive covalent organic frameworks for lithium ion batteries by microwave ultrasonic coupling

Abstract

The design and construction of high-capacity covalent organic framework (COF) electrode materials and the study of energy storage mechanism are still facing challenges. COFs have received academic interest as electrode materials for lithium ion batteries (LIBs), while the exploitation of pristine COFs is restricted by insufficient conductivity and active sites, partly due to the lack of hierarchical pores. Herein, we report a flexible synthesis solution for the preparation of highly ordered two-dimensional nanoporous COFs. Triphenylene-based covalent organic frameworks (TP-COFs) have been successfully used as anode electrode materials for LIBs for the first time. Additionally, a systematic study has been conducted on the improvement of lithium storage performance of TP-COF anodes using different synthesis methods, with the aid of microwave ultrasonic coupling. The TP-COF prepared by microwave ultrasonic coupling (Mw-4@U) displays a cheese-shaped structure with a significant amount of enriched micropores. The charge–discharge profile of Mw-4@U demonstrates a remarkable reversible capacity of 1469.7 mA h g⁻¹ after 120 cycles at the rate of 0.1 A g⁻¹.