The Preparation Of The Perovskite-type Oxide LaFeO₃ And Its Electrochemical Performance

In this paper,a stearic acid combustion method was applied to prepare perovskite-type oxide LaFeO₃,and the materials was used as negative electrode materials of the nickel/metal hydride（MH/Ni）secondary battery at high-temperature（60 ℃）.However the inherent limiting factors that weakened their practical application as he nickel/metal hydride（MH/Ni）secondary battery.In this paper we prepare LaFeO₃-rGO composites with La Fe O₃ and rGO by different rGO content（8%,10%,12%）using ultraphonic stirring and lyophilization method.The microstructure,electrochemical properties and kinetic performance of the composites were systematically investigated.The maximum discharge capacity was 334.6 mAh g-1 compare to pristine perovskite-type oxide La Fe O₃ only 209.5mAh g-1.The electrochemical discharge capacity was greatly improved through this method.In the other hand,the charge retention,cyclic stability,Impedance and other electrochemical properties were improved obviously.This result can be explained that the rGO has many excellent physical and chemical properties such as great electrical conductivity,larger specific surface area,so when it compositing with the perovskite-type oxide La FeO₃,it will increase the specific surface area of the composite and further improve the electrochemical properties.Expect this method to improve the electrochemical properties of the perovskite-type oxide LaFeO₃ by compositing with rGO,we also explored other factors that can change the performance of the perovskite-type oxide La FeO₃ that working as negative electrode materials of the nickel/metal hydride（MH/Ni）secondary battery,and the sintering temperature is also a very important factor that can effect the electrochemical properties,in this paper,we explored the different sintering temperature（1200 ℃,1100 ℃,1000 ℃,850 ℃,700 ℃,600 ℃,500 ℃）.Through the SEM and TEM patterns that we can see when the sintering temperature is high probably over 850 ℃,the crystal particles were aggregating together and when the sintering temperature is under 850 ℃,the crystal particles were dispersed well and the particle sizes was small compare to that sintering at high temperature.So it will have larger specific surface area.When the sintering temperature is 600 ℃ it has the maximum discharge capacity and almost 570 mAh g-1,the other electrochemical properties were also remarkably improved.