| Mg alloy is expected to be used in the anode of Metal-air battery due to its light weight and high theoretical voltage.However,there is still a big gap between the development potential and practical application of Mg-air batteries,making them less widely used than Al-air batteries and Zn-air batteries.The main reason is that its serious self-corrosion and negative differential effect become a stumbling block to the development of Mg-air battery,which makes the discharge products easy to accumulate on the surface of Mg anode and reduces the discharge performance.Therefore,the modification of anode material plays an important role in improving the performance of Mg-air batteries.In this article,as-cast Mg-2Zn-1Ca alloy was chosen as the research target.Firstly,it is homogenized,then hot compressed,and finally annealed at low temperature.The microstructure,electrochemical behavior and discharge properties of Mg-2Zn-1Ca alloy were investigated by metallographic microscope,X-ray diffraction（XRD）,scanning electron microscope（SEM）,potentiodynamic polarization curve（PDP）,electrochemical impedance spectroscopy（EIS）,hydrogen evolution immersion test and CT2001ALAND test system.The main research results are as follows:（1）After homogenization,the grain size of the alloys augment,the volume percentage of the second phases reduce,and the self-corrosion rate reduce.HT2alloy（homogenized at 440℃for 24 h）has the lowest corrosion rate of 0.07 mm year-1,which is about 1/3 of that of as-cast alloy.Among all the experimental alloys,HT2 alloy has the best discharge performance.At 10 m A cm-2,the anode utilization rate and capacity density of HT2 alloy reach 68.87%and 1477.10m Ah g-1,respectively,which are 14.51%and 26.59%higher than those of as-cast alloy,respectively.（2）The true stress-strain curve of Mg-2Zn-1Ca alloy revealed that the peak stress increases as the increment of strain rate and the decrease of deformation temperature.No dynamic recrystallization was observed under low temperature and high strain rate compression,and the dynamic recrystallization reached the maximum under 375℃and 0.001 s-1.The corrosion resistance of Mg-2Zn-1Ca alloy is better under the condition of high deformation temperature and low strain rate,and 375-0.001 alloy has the best corrosion resistance and discharge performance.At 10 m A cm-2,the anode utilization rate,capacity density and energy density of the alloy are 58.08%,1303.37 m Ah g-1and 1591.94 m Wh g-1,respectively.（3）After hot compression,it is annealed at low temperature,the grain distribution of Mg-2Zn-1Ca alloy is more uniform and the percentage of the second phases decrease.The reduction of the second phases reduces the number of galvanic corrosion and increases the corrosion resistance.The discharge properties of Mg-2Zn-1Ca anode alloy are greatly improved after annealing treatment.At 10 m A cm-2,the specific capacity,specific energy and anode utilization of the annealed alloy are 1830.10 m Ah g-1,1953.40 m Wh g-1and71.92%. |
PDF Full Text Request