The Use of Spray-Dried Mn3O4/C Composites as Electrocatalysts for Li-O2 Batteries

The electrocatalytic activities of Mn3O4/C composites are studied in lithium-oxygen (Li-O-2) batteries as cathode catalysts. The Mn3O4/C composites are fabricated using ultrasonic spray pyrolysis (USP) with organic surfactants as the carbon sources. The physical and electrochemical performance of the composites is characterized by X-ray diffraction, scanning electron microscopy, particle size analysis, Brunauer-Emmett-Teller (BET) measurements, elemental analysis, galvanostatic charge-discharge methods and rotating ring-disk electrode (RRDE) measurements. The electrochemical tests demonstrate that the Mn3O4/C composite that is prepared using Trition X-114 (TX114) surfactant has higher activity as a bi-functional catalyst and delivers better oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic performance in Li-O-2 batteries because there is a larger surface area and particles are homogeneous with a meso/macro porous structure. The rate constant (k(f)) for the production of superoxide radical (O-2(center dot-)) and the propylene carbonate (PC)-electrolyte decomposition rate constant (k) for M3O4/C and Super P electrodes are measured using RRDE experiments and analysis in the 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6))/PC electrolyte. The results show that TX114 has higher electrocatalytic activity for the first step of ORR to generate O-2(center dot-) and produces a faster PC-electrolyte decomposition rate.