Facile one-pot synthesis of low cost MnO2 nanosheet/Super P Li composites with high oxygen reduction reaction activity for Zn-air batteries

Facile green and scalable synthesis of low-cost nonprecious metal electrocatalysts which favor a four-electron pathway for the oxygen reduction reaction (ORR) are in great need for high-performance metal-air batteries. Herein, an ultrasonication-assisted synthesis method of preparing MnO2 nanosheets anchored on carbon black (MnO2/Super P Li) ORR catalyst is proposed. Three kinds of MnO2 nanostructures can be controlled and conformably deposited on Super P Li backbone. The MnO2/Super P Li composites facilitates a four-electron ORR process and demonstrates superior stability than the benchmark catalyst Pt/C in alkaline solutions. Moreover, the Zn-air battery using one of the MnO2/Super P Li catalysts displays a specific capacity of 705 mA h g−1 and the voltage platform is almost unchanged after discharge for 180 h. The high ORR activity of the hybrid catalyst can be attributed to the MnO2 nanosheets uniformly grown on the Super P Li three dimensional (3D) framework and the appropriate Mn(Ⅲ)/Mn(Ⅳ) of the MnO2/Super P Li composite which can magically catalyze the reduction of hydrogen peroxide. Due to the high ORR activity and the superior stability, low cost MnO2/Super P Li catalysts lends itself well to potential applications in renewable energy conversion devices. [Display omitted] •An ultrasonication-assisted synthesis method to make MnO2/Super P Li was proposed.•The reaction doesn't use organic solvent and the temperature is lower than 100 °C.•The MnO2/Super P Li has pronounced ORR activity due to the flower-like structure.•The flower-like structure prevents the agglomeration of MnO2.