Study Of The Mn₃O₄ Nano-particles Synthesis And The Electrochemical Performance In Lithium-oxygen Battery

As a kind of clean energy with high specific power, lithium-oxygen battery has drawn widespread attention at home and abroad. Manganite can be used as catalytic material for the cathode electrochemical reaction of lithium-oxygen battery due to its good catalytic activity. A simple aqueous solution precipitation route to synthesize Mn3O4 nanoparticles with CH3 OH and KMn O4 was reported in this research. The solid product was found to be Mn3O4 nanoparticles by X-ray diffraction(XRD) and scanning transmission electron microscopy(SEM). The results showed that the Mn3O4 nanoparticles had high purity and crystallization, and the average particle size was about 60 nm. The liquid products was testified by Uv-Vis and FT-IR Spectrometer, showing that CH3 OH was oxidated to CO2(CO32-). The reaction mechanism of nano-Mn3O4 preparation is as follow.4 3 3 4 2 3 2 218 KMn O +13CH OH ?6Mn O ?+9K CO +4CO -+26H OFoamed nickel was chosen as supporter and current collector, and KB conducted carbon and nano-Mn3O4 were chosen as materials to make oxygen cathode. The oxygen cathode with optimal catalytic activity was obtained when the mix proportion of cathode material was wC: wMn3O4=7:3. The experimental results of constant-temperature and constant-current discharge tests indicated that the discharge capacity of battery increased first and then decreased with the increase of conductive carbon mass, and the highest discharge capacity could be obtained when the conductive carbon mass was 25-40mg·cm-3. A similar interrelation was found between battery discharge capacity and catalyst mass fraction, and the highest discharge capacity could be obtained when the catalyst mass fraction was 30%. A optimized lithium-air cathode was finally prepared, of which the initial discharge capacity could reach 2820 m Ah·g-1carbon and 3869 m Ah·g-1carbon when the discharging current was 0.5 m A·cm-2 and 0.1 m A·cm-2 respectively. Besides, the charge-discharge tests showed that a relatively higher discharge flat(2.81V)and lower charge flat(4.22V)could be obtained in 50?.