The Research Of The Cathode Materials And Charge-discharge Performence In Lithium-air Battery

With the depletion of the fossil energy, the research of the new energy get more and more people’ attention. As for the rechargeable batteries, lithium-air battery is focused by people due to its high specific energy and friendly environment. The lithium-air battery’ energy density is 5 to 10 times than the conventional lithium ion battery, the theoretical specific energy can get 11140 Wh/kg which can match with the gassline.In the lithium-air battery, the rection of the positive plays an important role. The requirement for the cathode material is to be able to diffuse gas, to store the discharge products and to conduct electron. The carbon nanotube and graphene due to its large specific area, good gas diffusivity, stable chemical properties and excellent conductivity have become a better kind of the cathode materials.This paper will introduce the classification and properties of carbon nanotube as well as the properties and application of graphene, analyze the principle of the lithium-air battery and the advantages of carbon nanotube and graphene as the cathode materials.This paper will also introduce the methods of characterization for carbon nanotube and graphene, including transmission electron microscopy (TEM) scanning electron microscope (SEM)、Raman spectrometer and Energy dispersive X-ray spectra (EDX)The catalyst MnO2 and Pd with carbon nanotubes composite was prepared as air electrode,and assembled cells to be tested, and compared with the pure carbon nanotubes assembled battery,the results show that MnO2 can reduce the overpotential, Pd is good to improve the cycle performance of battery; Preparing the graphene by using the thermal reduction grapheme oxide and the Chemical Vapor Deposition growth method,The graphene as a cathode material for testing by assembled cells., the results show that the former discharge specific capacity is bigger than that of the latter; Preparating MnO2/Graphene/CNT composite material under different current densities tested found the smaller current density, the bigger of the discharge specific capacity.In this research, there are some defects to overcome, such as the short discharge cycle, the small discharge specific capacity and so on. We will improve the performance of the lithium-air battery and reduce the overpotential by improving the testing device and adding catalyst to cathode.