posted on 2022-01-25, 12:33authored byDongdong Li, Jianwen Liang, Stuart J. Robertson, Yingtong Chen, Naiguang Wang, Minhua Shao, Zhicong Shi
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.