The rechargeable Zinc-air battery is a clean technology for energy storage applications but is impeded by the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)...

With an anticipation of their use in electric vehicles, Li-O batteries are found to be attractive despite their complex chemistry and drawbacks. To be successful, cathode materials that are robust enough to overcome the sluggish kinetics of the charge-discharge reactions are essential. This work reports sonochemically synthesized porous MnCo O /graphene (MCO/G) as a hybrid cathode material in nonaqueous Li-O batteries. The MCO/G hybrid is synthesized in less than four hours and offers a strong synergistic coupling between the MnCo O nanospheres and graphene sheets. It catalyzes the oxygen reduction through a three-electron-transfer process and initiates the oxygen evolution at 1.55 V vs. RHE in basic medium. A small charge-discharge voltage hysteresis of 0.8 V and a cycle life of 250 cycles at a limited capacity of 1000 mAh g in a tetraglyme-based nonaqueous Li-O battery is demonstrated. The porous channels created on the sonochemically synthesized cathode facilitates easy oxygen adsorption onto the active sites to accommodate more discharge products following its decomposition. It exhibits a better rate capability in comparison to the widely used Vulcan carbon and benchmark Pt/C catalysts. The excellent cyclability, rate capability, and low overpotential demonstrates MnCo O /graphene composite as a promising cathode candidate for Li-O batteries. The porous nanosphere architecture with internal oxygen diffusion pathways and peripheral conductive graphene extensions fulfils the requirements that a robust cathode is expected to have to overcome the harsh Li-O battery conditions and to serve as a high-rate-capable cathode for Li-O batteries.

MnCo2O4–GS nano composite by a one-pot sonochemical method and its high performance as an active cathode catalyst for a Zn–air battery.