LaCoO3−δ–CoO–Partially Exfoliated Carbon Nanotube Composites as Efficient Oxygen Reduction Catalysts for Zn–Air Batteries

Zn–air battery with advantages of high capacity, safety, and environmental friendliness is an ideal candidate for the next-generation energy conversion and storage system. Highly efficient oxygen reduction reaction catalysts with low cost play an important role in Zn–air batteries. Herein, a LaCoO3−δ–CoO–partially exfoliated carbon nanotube (CNT) composite (LaCoO3−δ–CoO–CNT) is synthesized through a facile ball milling process. With the help of the sufficient energy input through ball milling, the CNT is partially exfoliated with LaCoO3−δ–CoO. The half-wave potential of LaCoO3−δ–CoO–CNT reaches 0.74 V vs RHE, and its average electron transfer number (n = 3.82) is close to 4. The working voltage of Zn–air battery with LaCoO3−δ–CoO–CNT as cathode catalyst reaches 1.26 V at 5 mA cm–2 and 1.19 V at 20 mA cm–2. In addition, the battery can maintain a stable working voltage during the long-time galvanostatic discharge at different current densities. The enhanced catalytic ability of LaCoO3−δ–CoO–CNT is mainly due to the synergistic effect of LaCoO3−δ and CoO, partially exfoliated CNT, and abundant oxygen vacancies.