Negative Materials And Inhibitor For Magnesium Battery

There is a great potential in the energy field because of the high electronegativity,chemical activity and energy density of magnesium alloys. However, the wideapplication of magnesium battery is restricted and impeded by the self-corrosionproblem of magnesium alloys. Therefore, the composition of magnesium alloy negativematerial and the concentration of the electrolyte corrosion inhibitor are optimized bydifferent alloy element and inhibitors in this work, in order to reduce the self-corrosionof negative material and improve the discharge performance of magnesium battery.In this work, negative material for magnesium battery and the inhibitor have beenstudied by open potential （COP）, linear sweep voltammetry （LSV）, electrochemicalimpedance spectroscopy （EIS）, Tafel polarization curve, X-ray diffractiontechnique（XRD） and discharge measurement of coin-type cells. On the aspect ofnegative material, the effect of Al、Zn content on the electrochemical behavior ofMg-Al-Zn alloy and Li content on the electrochemical behavior of Mg-Li-Al alloy inMg（ClO₄）₂solution was researched, and the discharge property of relevant batterieswere discussed. On the aspect of the inhibitor，the effect of different inhibitors on theelectrochemical behavior of AZ31and discharge property of AZ31battery; and theeffect of Li₂CrO₄concentration on the electrochemical behavior and discharge propertyof relevant batteries have been studied. The results are as follows:The corrosion of AZ31in1mol/L Mg（ClO₄）₂solution was improved by adding0.1%different inhibitors. Li₂CrO₄has the best corrosion inhibition effect, the inhibitionefficiency is99.84%, and the discharge property of magnesium battery with0.1%Li₂CrO₄is the best, with smooth discharge curve, stable discharge process, highoperating voltage（between1.6V to1.7V）and high utilization rate of positive activemateria（l41.42%）. The ability of these inhibitors to improve the discharge performanceof AZ31alloy battery is: Li₂CrO₄＞phytic acid＞Na₂SnO₃＞SDBS＞BTAH.With the increase of Al content, the corrosion property of Mg-xAl-1Zn alloy in1mol/L Mg（ClO₄）₂solution was increased, the electrochemical activity and the opencircuit voltage（OCV） of magnesium dry batteries was reduced. AZ61battery has thelowest OCV, being2.21V. The discharge time, utilization of the positive activematerial and the comprehensive discharge performance of magnesium dry battery are allimproved with the increase of Al content. Considering the inhibition of corrosion inhibitor and the electrochemical activity of anode material, AZ31is more fit formagnesium-manganese dry battery. When there is0.3%Li₂CrO₄, the battery has thebest discharge property, the OCV is2.17. Operating voltage is between1.5V to1.7V,and the utilizations of the positive active material are53.06%.The corrosion resistance of Mg-3Al-xZn alloy and comprehensive dischargeperformance of magnesium dry battery are improved with the increase of Zn content.The effect of Zn content on the corrosion potential of Mg-3Al-xZn alloys in1mol/LMg （ClO4）2solution is very little. Moreover, the OCV of Mg-3Al-xZn alloy batteriesalters little as well, keeps at about2.2V. If there is no inhibitor in the electrolyte system,the comprehensive discharge performance of Mg-3Al-xZn batteries are almost the samewhen w（Zn）)≥2%, the operating voltage keeps between1.5V to1.7V, discharge timeare about10hours and the utilization rate of the positive active material are very close.Li₂CrO₄is a good corrosion inhibitor of Mg-xAl-xZn, the discharge property ofmagnesium dry battery is greatly improved with the addition of Li₂CrO₄. In this work,the AZ35magnesium dry battery with0.05%Li₂CrO₄has the best discharge property,the OCV is2.24V, operating voltage is between1.5V to1.7V, and the utilization rateof the positive active material is62.33%.Mg-Li-Al alloy battery has high OCV and operating voltage, but short dischargetime, low utilization rate of the positive active material and poor comprehensivedischarge performance. The effect of Li content on discharge property is very little,while the comprehensive discharge performance is improved by adding Li₂CrO₄. LA91battery has the best comprehensive discharge performance, with high OCV （about2.3V）and the highest operating voltage （1.7～1.8V）. However, there is serious voltagehysteresis problem, which has been shown to be reduced by adding Li₂CrO₄, and becontrolled when w （Li₂CrO₄）=0.5%.