The Discharge Properties And Corrosion Behaviors Of The Mg-Ca-Zn Anodes For Primary Mg-Air Batteries

Mg-air batteries,as a new type of fuel cell,has a series of advantages such as high energy density,low density,abundant resources,low price and environmental friendly.it is an ideal new type of energy to replace traditional energy and meet the development needs of modern society.However,its wide application is restricted by serious self-corrosion,poor discharge activities and low discharge efficiency.The effects of chemical composition,hot extrusion and homogenization treatment on the microstructure,corrosion behavior and discharge properties of Mg-Ca-Zn alloys(XZ10,XZ12,XZ15,XZ18)used as anode for magnesium air batteries were investigated.The main experimental results are as follows:(1)Among the four cast alloys,XZ12 alloy has the best discharge properties because of stable discharge voltage and little effect of the chunk effect.However,the poor hydrogen evolution reaction and serious chunk effect of XZ10 alloy significantly reduce the discharge efficiency.The XZ15 and XZ18 alloys can maintain stable voltage at low current density,but at high current density,the discharge voltage decreases obviously,and both of them are affected by a certain block effect,so the discharge performance of both of them is not high.(2)After hot extrusion,some intermediate phases precipitate out and the grain size decreases obviously.Among the four extruded Mg-Ca-Zn alloys,XZ12 alloy has the best discharge properties,mainly because of its low hydrogen evolution corrosion rate,good corrosion resistance,and stable discharge voltage,which can maintain stable discharge activity.,The discharge performance of the extruded alloy anode decreases compared with the cast alloy,because of the number of mesophases increases,the galvanic corrosion increases and the self-corrosion rate increases.(3)After homogenization treatment at 633 K for 24 h,the second phases in the as-cast and as-extruded XZ12 alloys significantly reduced.The corrosion properties of cast XZ12 alloy is reduced due to the destruction of the network distribution of the second phases.The corrosion properties of extruded XZ12 alloy are increased due to the decrease of the content of the second phases and the weakening of the galvanic corrosion.After heat treatment,casting state and squeezed state XZ12 alloy corrosion products is not easy to accumulate,higher discharge voltage,discharge stability significantly increased,its discharge performance is improved.