Dandelion-like NiCo₂O₄ hollow microspheres as enhanced cathode catalyst for Li-oxygen batteries in ambient air

The high overpotentials of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the air cathode are still big challenge to be overcome for the high performance non-aqueous lithium-air batteries (LABs), especially in ambient air. In this paper, dandelion-like NiCo₂O₄ hollow microspheres are prepared through a simple self-assembled hydrothermal process as cathode catalyst. The assembled LABs show relative high discharge potential in different oxygen partial pressure, and can deliver a reversible capacity of 8019 mAh·g⁻¹ at the current density of 300 mA·g⁻¹ with stable cycle performance for at least 40 times in ambient air. The excellent performance of NiCo₂O₄ cathode can be attributed to the dandelion hollow structure, together with the abundant oxygen vacancies, which would enhance the ORR and OER process. The study confirms the feasibility of dandelion-like NiCo₂O₄ hollow spheres as efficient cathode for the LABs in ambient air.