Microstructure And Properties Of Anode Materials For Aluminum-Air Batteries

Aluminum-air batteries with the merits of high energy density,low cost,non-toxicity,environmental benignity and so on,have shown promising potential application in electrical vehicles,potable electronics,and large scale storage.However,there exist some concerns in the anode materials during the discharge such as self-corrosion,passivation and so on,which lower the batteries' energy density,operating voltage,and safety concern and limit the development of aluminum-air batteries and commercial applications.To improve performance of the anode materials in aluminum-air batteries,the use of high-purity aluminum and alloying are effective methods.Pure aluminum with different grades and Al-0.08Sn-xMg(x=0.2,0.6,1.0,1.4)alloy with different contents of Mg were chosen for research.The composition of the materials is analyzed using Direct Reading Spectrometer(DRS)and Glow discharge Mass Spectrometer(GDMS).The microstructure,corrosion resistance,electrochemical properties are studied by means of Metallurgical Microscope(OM),X Ray Diffraction(XRD),Scanning Electron Microscope(SEM)and electrochemical testing techniques including Open Circuit Potential(OCP),Electrochemical Impedance Spectroscopy(EIS),Linear Sweep Voltammetry(LSV),Chrono Potentiometry(CP)and so on.The main details and results are as follows:(1)The corrosion resistance and electrochemical performance of pure aluminum with different grades.On one hand,the increase of purity enhances the corrosion resistance of anode materials.On the other hand,it improves the electrochemical performance under open circuit potential and certain current intensities.The main reason is the decrease of impurity elements Fe,Si,Cu and their catholic inclusion.However,it should be noted that aluminum with certain purity may have different alloying elements and contents and these tiny distinctions may make a significant difference in anode's performance.(2)The effect of Mg content on microstructure and properties of Al-0.08Sn-xMg alloy was studied.The results show that the increase of the Mg content will reduce the content of Sn in the precipitates in the alloy,increase the number of Sn-containing precipitates,which act as active sites.So the increase of the Mg content enhances electrochemical activation of anode.The electrochemical performance of Al-0.08Sn-xMg alloy under open circuit potential and current density improves with the increase of Mg content.In the Al-0.08Sn-xMg alloy,corrosion is easy to occur between the dendrites.The change in Mg content will affect the number,size and distribution of dendrite in the microstructure,thus affecting the corrosion resistance of the alloy.(3)It is found that in the Al-0.08Sn-xMg(x=0.2,0.6,1,1.4)alloys,the Al-0.08Sn-0.6Mg alloy maintains a good discharge performance in the condition of large current.The alloy also has good corrosion resistance,exhibiting excellent integrated performance.