| Aluminum-air battery is a kind of promising electrochemical power source,which has the characteristics of wide source of raw materials,high energy density,convenient,environmentally friendly.Air electrode is the core of Al-air battery,and the key to improve the performance of Al-air battery is to prepare high oxygen reduction reaction(ORR)activity catalyst.At present,there are many catalysts such as noble metal,metal oxide,metal chelate,perovskite catalysts and new-type catalysts.Among them,MnO2 has the advantages of high catalytic activity,wide source,easy preparation and so on.In this thesis,MnO2 loaded actived carbon(AC)was prepared by ultrasonic hydrothermal method.The effects of calcination temperature,KMnO4 concentration and reaction time on the catalysts were studied.In order to analyse and characterize the catalysts and catalytic layers,detections and analysises such as Thermogravimetry(TG/DSC),Raman spectroscopy(Raman spectra),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy spectrum analysis(EDS),cyclic voltammetry(CV)and linear scanning(LSV)and constant current discharge(I-V)were employed.At the same time,three-dimensionally-ordered-porous(3DOP)LaMnO3 was prepared by template method,and was analysed and compared to MnO2/AC subsequently,the experimental contents and results are given as follows.1>KMnO4 reacted with active carbon by using ultrasonic hydrothermal method in order to prepare MnO2/AC,and the effect of calcination temperature,KMnO4 concentration and reaction time on catalytic performances was studied.In the experiment of calcination temperature optimization,properties of MnO2/AC prepared at 200℃,250℃，300℃,350℃,400℃ were studied,revealed that δ-MnO2/AC was obtained when calcined at 350 ℃,and the reduction peak current density and polarization current density reached the maximum.The discharge voltages of full battery assembled by Mn02/AC calcined at 350℃ were 1,170 V,1.084 V,0.904 V,0.822 V,0.714 V at the current density of 10 mA.cm-2,20 mA.cm-2,30 mA.cm-2,40 mA.cm-2、50 mA.cm-2 respectively.2>Subsequently,catalytic performances of MnO2/AC synthesized at KMnO4 concentrations of 10 g.L-1,20 g.L-1,30 g.L-1,40 g.L-1,50 g.L-1 were studied.The ORR ability of catalyst was the best when the KMnO4 concentration was set at 20 g.L-1,owning to the best relative content of MnO2 and actived carbon.The discharge voltages were 1.250 V,1.177 V,1.163 V,1.133 V,1.090 V at the current density of 10 mA.cm-2,20 mA.cmf2,30 mA.cm-2,40 mA.cm-2、50 mA.cm-2 respectively.3>Finally,the reaction times of 0.5 h,1.0 h,.1.5 h,2.0 h,2.5 h were studied,revealed that when the reaction time was 1 h,the amount of MnO2 and grain size and the discharge performance was the best.The optimal condition was carried out through orthogonal method:T=350℃,C=20 g.L-1,t=1 h.After the catalyst prepared under the optimal condition was use into the air electrode,the discharge voltage of Al-air battery were 1.294 V,1.250 V,1.221 V,1.163 V,1.097 V respectively when the current density were 10 mA.cm-2,20 mA.cm-2,30 mA.cm-2,40 mA.cm-2 50 mA.cm-2.4>In addition,the catalytic performance of three-ordered-porous(3DOP)perovskite structure LaMnO3 was studied.Uniformed size and neatly arranged SiO2 template was synthesed by Stober-Frink method.The pore size of 3DOP LaMnO3 prepared by using SiO2 template was about 330 nm,and the specific area reached 46.831 m2.g-1.The catalytic activity was much higher than that of the LaMnO3 prepared by co-precipitation method and exhibited better discharge performance.After constant current discharge test,the discharge voltages of 3DOP LaMnO3 were 1.419 V,1.237 V,0.998 V,0.930 V,0.711 V at the current density of 10 mA.cm-2,20 mA.cm-2,30 mA.cm-2,40 mA.cm-2、50 mA.cm-2 respectively.But compared to MnO2/AC,the discharge performance of LaMnO3 was poor at high current density. |
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