| Magnesium alloys, with its low density, high electrochemical activity, lowstandard electrode potential and high energy density, have a broad prospect in the fieldof chemical power source. However, the serious hydrogen evolution, voltage hysteresisand high processing cost of magnesium alloy have become a barrier of the extensivedevelopment of magnesium battery anode materials. Therefore, the electrochemicalproperties and discharge performance of AZ31B magnesium alloy with differentprocessing conditions were investigated. Extruded, rolled, cast-rolled and as-castAZ31B magnesium alloys were prepared as the anode materials. It makes the theoreticalbasis for the cost-effective magnesium battery anode materials.Based on the Tafel polarization curve, electrochemical impedance spectroscopy(EIS), chronopotentiometry, gravity method and electronic scanning electronmicroscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and battery dischargetest, the electrochemical properties of AZ31B magnesium alloy with differentprocessing conditions were studied. The magnesium battery was made with themagnesium anode, self-made MnO2air cathode and the3.5wt.%NaCl solution. Thedischarge performance of magnesium air battery at5mA·cm-2and10mA·cm-2, togetherwith intermittent discharge at5mA·cm-2have been investigated respectively. The fourkinds of inhibitors of lithium chromate dehydrate, tryptophan, hexamethylenetetramine,lanthanum acetate has been added to the magnesium air battery to study the constantand intermittent discharge performance. The results are as follows:①In the test of electrochemical performance, the extruded magnesium alloy hasnegative equilibrium potential and high electrochemical activity, lower corrosioncurrent density of0.054mA·cm-2due to the finer grain size and uniform organizationcomposition. Its corrosion resistant performance is the best; Rolled and cast-rolledmagnesium anode have almost the same corrosion resistant which is lower thanextruded magnesium. As-cast sample has positive equilibrium potential, small chargetransfer resistance, resulting in severe self-corrosion. The products of as-castmagnesium alloy are compact of big block, which is difficult to falling off. Theproducts of extruded magnesium are loose and fine. Except for the as-cast anode, theother three anodes have relatively stable curves.②The four kinds of magnesium air battery had the similar open circuit voltage, at around1.61V. During the constant discharging at5mA·cm-2, Extruded sample had thesmooth discharge curves at about1.00V for a long time; Rolled and cast-rolled samplesdischarges for42h, slightly lower than the extruded one. While the discharge curves areless smooth than extruded anode; As-cast discharges for the shortest time and thedischarge curve fluctuate heavily. At the discharging of10mA·cm-2, there are similarresults with the discharging of5mA·cm-2. Discharge capacity of extruded sample wasless than rolled and cast-rolled, while the latter showed slight fluctuations and seriouspolarization. The extruded sample still showed a good discharge performance duringIntermittent discharge. As-cast battery had sudden short-circuit and the voltage droppedto a low value, which seriously influenced the stability of the battery dischargeperformance.③Adding the inhibitors, the corrosion resistance performance had been improved.The equilibrium potential of magnesium anode shifted positively and current densitywas reduced. and the inhibition efficiency of Li2CrO4was97.43%. Four kinds ofcorrosion inhibitors had little effect on open circuit potential(OCV) of magnesium airbattery. The discharge potential and the cycle discharge performance had beenimproved. After adding inhibitor, the discharge time was extended and discharge cycleperformance was better during the intermittent discharge process. The influence of fourkinds of corrosion inhibitors for magnesium air battery hysteresis effect was notobvious. The ability of these inhibitors to improve the discharge performance of AZ31battery is: Li2CrO4> tryptophan> hexamethylenetetramine> Lanthanum acetate. |
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