Single Metal Site and Versatile Transfer Channel Merged into Covalent Organic Frameworks Facilitate High-Performance Li-CO2 Batteries

• Published in: ACS central science Vol. 7; no. 1; pp. 175 - 182
• Main Authors: Zhang, Yu, Zhong, Rong-Lin, Lu, Meng, Wang, Jian-Hui, Jiang, Cheng, Gao, Guang-Kuo, Dong, Long-Zhang, Chen, Yifa, Li, Shun-Li, Lan, Ya-Qian
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.01.2021
• ISSN: 2374-7943; 2374-7951
• DOI: 10.1021/acscentsci.0c01390

The sluggish kinetics and unclear mechanism have significantly hindered the development of Li-CO2 batteries. Here, a Li-CO2 battery cathode catalyst based on a porphyrin-based covalent organic framework (TTCOF-Mn) with single metal sites is reported to reveal intrinsic catalytic sites of aprotic CO2 conversion from the molecular level. The battery with TTCOF-Mn exhibits a low overpotential of 1.07 V at 100 mA/g as well as excellent stability at 300 mA/g, which is one of the best Li-CO2 battery cathode catalysts to date. The unique features of TTCOF-Mn including uniform single-Mn­(II)-sites, fast Li+ transfer pathways, and high electron transfer efficiency contribute to effective CO2 reduction and Li2CO3 decomposition in the Li-CO2 system. Density functional theory calculations reveal that different metalloporphyrin sites lead to different reaction pathways. The single-Mn­(II) sites in TTCOF-Mn can activate CO2 and achieve an efficient four-electron CO2 conversion pathway. It is the first example to reveal the catalytic active sites and clear reaction pathways in aprotic Li-CO2 batteries.