Self-Assembled 3D Foam-Like NiCo₂O₄ as Efficient Catalyst for Lithium Oxygen Batteries

A self-assembled 3D foam-like NiCo₂O₄ catalyst has been synthesized via a simple and environmental friendly approach, wherein starch acts as the template to form the unique 3D architecture. Interestingly, when employed as a cathode for lithium oxygen batteries, it demonstrates superior bifunctional electrocatalytic activities toward both the oxygen reduction reaction and the oxygen evolution reaction, with a relatively high round-trip efficiency of 70% and high discharge capacity of 10 137 mAh g^-1 at a current density of 200 mA g^-1, which is much higher than those in previously reported results. Meanwhile, rotating disk electrode measurements in both aqueous and nonaqueous electrolyte are also employed to confirm the electrocatalytic activity for the first time. This excellent performance is attributed to the synergistic benefits of the unique 3D foam-like structure and the intrinsically high catalytic activity of NiCo₂O₄.