Lithium-oxygen (Li-O₂) battery is one of the most promising batteries due to its high theoretical energy density. However, the poor catalytic performance of its air-cathode impeded its commercialization.

Recently, a joint research group led by Prof. BAO Xinhe and Prof. WU Zhongshuai from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has fabricated two-dimensional (2D) Mn₃O₄ nanosheets with dominant crystal planes on graphene (Mn₃O₄ NS/G) as efficient oxygen catalysts for Li-O₂ batteries, achieving ultrahigh capacity and long-term stability.

This study was published in ACS Catalysis on Oct. 7.

Designing oxygen catalysts with well-defined shapes and high-activity crystal facets can effectively regulate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the three-phase interfaces, but it is still remains challenging.

The researchers indicated that the Mn₃O₄ NS/G with the (101) facets and enriched oxygen vacancies offered a lower charge overpotential of 0.86 V than that of Mn₃O₄ nanoparticles on graphene (1.15 V).

Moreover, Mn₃O₄ NS/G cathode exhibited long-term stability over 1,300 hours and ultrahigh specific capacity up to 35,583 mAh/g at 200 mA/g, outperforming most Mn-based oxides for Li-O₂ batteries reported.

Both the experimental and theoretical results proved the lower adsorption energy of Mn₃O₄ (101) for the discharge product Li₂O₂ in comparison with Mn₃O₄ (211), manifesting the easier decomposition of Li₂O₂ during the charging process.

"This work may provide clues for engineering Mn-based materials with defined crystal facet for high-performance Li-O₂ batteries," said Prof. WU.

The above work was supported by the National Natural Science Foundation of China and Dalian National Laboratory for Clean Energy of CAS.