Seawater Activated Battery Magnesium Alloy Anode Materials Research

The magnesium electrode material is greatly concerned because of its low price, nontoxicity, steady discharge potential plateau, high energy density, plenty of resources, reproducible, etc. However, it hasn't been widely used partly due to such problem as passivation and corrosion, which makes it difficult to satisfy the practice. Therefore, it would be important significance and practical value to choose proper alloying elements and study their activity mechanisms on Mg anode materials. Further studies on accurate Mg alloy phase diagrams, the influence of second phases as well as microstructure evolution on electrochemical and corrosion properties of Mg anode materials are meaningful for alloy design.In this dissertation, the self-corrosion and electrochemical behaviors of AP65,Mg-3%Hg-2%Ga and AZ31 magnesium alloys in 3.5%NaCl solution were firstly investigated by chromatography hydrogen, weightlessness, circulation volt-ampere scanning, AC impedance, constant current potential, dynamic potential polarization, constant pressure discharge and so on many kinds of method. Then, it examines them as magnesium battery cathode material performance. Tomographic hydrogen and soaking results show that the self-corrosion activity of Mg-3%Hg-2%Ga is well than AP65 and AZ31. Constant current potential shows that the electrochemical activity of Mg-3%Hg-2%Ga and AP65 are well than AZ31, performance for anode polarization small open potential negative. AC impedance results show that the Rct values of Mg-3%Hg-2%Ga,AP65 and AZ31 increase gradually. Dynamic potential polarization results show that the corrosion current density values of Mg-3%Hg-2%Ga,AP65 and AZ31 decrease gradually. In the constant pressure discharge, the current density of Mg-3%Hg-2%Ga and AP65 is higher and more stable than AZ31.They are more application value in Mg batteries. Secondly, the surface morphology of magnesium alloy anode materials was studied by scanning electron microscopy. The types of corrosion and corrosion mechanism of magnesium alloy anode material were discussed. The scanning photos show that magnesium alloys for corrosive pitting corrosion types in 3.5% NaCl solution. Corrosion began by pitting corrosion expansion from the first local area and development into a hole comprehensive corrosion. Combining EDS analysis shows that the corrosion products mainly for Mg (OH) 2 compounds.Through existing magnesium alloy anode materials research, this paper further designed an accord with civil seawater activation cell with magnesium alloy anode materials Mg-A1-Sn series magnesium alloys. Through the design of six different ingredients of Mg-A1-Sn alloy series, and adding different content of magnesium alloy elements from anode materials and electrochemical corrosion properties. Using hydrogen method and soaking chromatography method to study the corrosion rate of Mg alloy. Research results show that, with the increase of the content of Al and Sn, magnesium alloy corrosion activity increase gradually; the corrosion active of Mg-6%A1-10%Sn is optimal in six components.The working voltage of Mg-A1-Sn series of magnesium alloys was studied by constant current and voltage. Research results show that, with the increase of the content of Al and Sn, Mg-A1-Sn series of magnesium alloys working voltage more negative and more stable. AC impedance results show that Mg-A1-Sn series of Mg alloy electrode system to contain adsorption impedance of electrode system. The study found that the electrode reaction among products and the adsorption ability of electrode reaction charge transfer impedance values with the increase of the content of Al,Sn decreases. Meanwhile, from numerical analysis on the Mg-A1-Sn series of magnesium alloys passivation block metal dissolution reaction ability is weak, magnesium alloy has strong corrosion activity. The corrosion product components and corrosion morphology of the Mg-A1-Sn series of magnesium alloys were analysed. Results show that the corrosion products of Mg-Al-Sn series of magnesium alloys are Mg (OH) 2,MgO style etc compounds. Corrosion was uniformity, corrosion product easy to fall off.Comprehensive Mg-A1-Sn series of Mg alloy corrosion and electrochemical performance, obtaining the best Mg-A1-Sn series of Mg alloy composition:Mg-6% of Sn Al-10%. KEY WORDS Magnesium battery, magnesium alloy anode material, electrochemical behavior, corrosion morphology, microstructure, alloying...