Micro-alloyed Mg-Al-Sn anode with refined dendrites used for Mg-air battery

The refined dendrites in micro-alloyed Mg-Al-Sn anode are constructed by using a thick-walled copper mold during the casting of liquid alloy. Greatly enhanced corrosion resistance at open circuit potential is achieved by these dendrites, which result in the formation of a protective film on the anode surface. The refined dendrites with weakened segregation of aluminum and tin also accelerate the spalling of oxidation products and alleviate the self-corrosion during battery discharge. All these aspects conduce to the desirable performance of Mg-air battery, since it shows higher discharge voltages and capacities than those using commercial AZ31 magnesium alloy and the same compositional Mg-Al-Sn sample with coarser dendrites. Moreover, the electrochemical corrosion mechanism directly related to the different dendrites in Mg-Al-Sn anodes is also unraveled based on microstructure characterization and electrochemical response.