Heterogeneous Bimetallic Organic Coordination Polymer-Derived Co/Fe@NC Bifunctional Catalysts for Rechargeable Li–O<sub>2</sub> Batteries
Dongdong Li, Jianwen Liang, Stuart J. Robertson, Yingtong Chen, Naiguang Wang, Minhua Shao, Zhicong Shi
Abstract
The Li–O2 battery has attracted substantial attention due to its high theoretical energy density. In particular, high-efficiency oxygen catalysts are very important for the design of practical Li–O2 batteries. Herein, we have synthesized heterogeneous crystalline-coated partially crystalline bimetallic organic coordination polymers (PC@C-BMOCPs), which are further pyrolyzed to obtain Co- and Fe-based nanoparticles embedded within rodlike N-doped carbon (Co/Fe@NC) as a bifunctional oxygen reduction reaction/oxygen evolution reaction (ORR/OER) catalyst used in the Li–O2 battery. Owing to excellent ORR/OER catalytic ability, the Co/Fe@NC bifunctional catalyst exhibits an efficient reversible reaction between O2 and Li2O2. Additionally, a large number of mesoporous channels are present in the core–shell Co/Fe@NC nanoparticles. These channels not only promote the diffusion of Li+ and O2, but also create ample room to store insoluble discharge product Li2O2. The Li–O2 batteries utilizing the bifunctional Co/Fe@NC oxygen electrode exhibit a large capacity of 17,326 mAh g–1, a long cycling life of more than 250 cycles, and excellent reversibility. This work provides a universally applicable strategy for designing nonnoble metal ORR/OER catalysts with excellent electrochemical performance for metal–air batteries.