Sonochemical synthesis of mesoporous MnO2 for Zinc-Air battery applications

MnO2 is one of the candidate materials for the application to electrochemical capacitors, Li-ion batteries, sensors and catalysts [1]. In energy-storage devices, nano structured MnO2 has been used as an active material because of its low cost and natural abundance as well as it being environmentally safe [2]. Sonochemical technique has proved to be useful method for generating nano structures of oxide materials with highly pure and unusual properties in short reaction times [3]. Here in, nanostructured MnO2 was synthesized using a simple one-step sonochemical method in the presence of poly (ethylene glycol)-block poly (propylene glycol)-block-poly (ethylene glycol) (P123) as a soft template as well as a reducing agent. Prepared samples have been characterized using X-ray diffraction (XRD), morphology of the samples has been characterized by field-emission scanning electron microscopy (FESEM). The pore structures of the prepared samples were tested by N2 adsorption-desorption measurements. The activity and stability of this catalyst was evaluated by preparing air electrodes with primary Zinc−Air batteries that consume ambient air. The XRD results indicated that MnO2 sample was poorly crystalline. The FESEM images showed that the nanostructure of MnO2 was composed. The size of nanoparticles were about 10-13 nm. A BET surface area of 87 m2/g is achieved for mesoporous MnO2 sample. The results of electrochemical tests revealed that the peak power density of Zinc-Air batteries were 136.05 mW/cm2. The cells galvanostatic discharge showed maximum discharge current density of 200 mA/cm2.