Research On Cathode Oxygen Reduction Reaction Catalyst And Magnesium Alloy Anode For Magnesium-air Battery

In this work,carbon supported platinum-molybdenum alloys?Pt-Mo/C?were studied as oxygen reduction reaction?ORR?electrocatalyst for magnesium-air batteries.Pt-Mo/C catalysts with different Pt:Mo atomic ratios were synthesized via an impregnation reduction method at room temperature in aqueous solution.The structural characterizations including XRD,EDS,TEM,XPS revealed that Pt-Mo alloy nanoparticles having an average size of 5 nm formed and distributed homogeneously on carbon support.Electrochemical measurements including CV and single-cell test showed that Pt-Mo/C catalysts exhibited better catalytic activity than Pt/C.The enhancement of catalytic activity can be attributed to two factors:Pt-rich surface formed on the Pt-Mo alloy particles and Pt5d-band vacancies increased due to the partial substitution of Mo for Pt.Among the Pt-Mo/C catalysts,Pt-Mo/C?3:1?showed the best performance with a maximum ORR current density of 21.14 mA cm^-2 in O₂-saturated NaCl solution and specific discharge capacity of 1311 mA h g^-1 in Mg-air battery,which are 164.9%and 11.8%higher than those of the Pt/C catalyst synthesized by using the same method(7.98 mA cm^-2 and 1156 mA h g^-1).A carbon-supported ionic porous polymer CoF@B-ph-ae/CNT was used as low-cost ORR catalyst for Mg-air batteries.Discharge curves of Mg-air batteries under different current density were tested.Under different discharge current,the specific capacity of Mg-air batteries with CoF@B-ph-ae/CNT was slightly smaller than that of commercial Pt/C.The voltage of the batteries with CoF@B-ph-ae/CNT was nearly 10%lower than that of commercial Pt/C.Batteries with CoF@B-ph-ae/CNT couldn't be started under large current density.So CoF@B-ph-ae/CNT could be an alternative for low current density discharge.Rare earth magnesium alloy GW102K and magnesium lithium alloy LAZ832 were studied as anode materials for Mg-air batteries.Commercial pure Mg and AZ31 were used for comparison.GW102K was more corrosion resistant and more active according to electrochemical characterization.At a small current density of 1mA cm^-2,GW102K had the highest discharge voltage.However,its specific capacity was only slightly larger than that of pure magnesium.This is due to GW102K containing a large number of heavy elements.The lithium-containing alloy LAZ832 had higher theoretical specific capacity,but it was not corrosion resistant.The corrosion resistance could be improved by adding elements Nb or Y.The addition of element Y resulted in a loose corrosion product film,which was good for discharge while Nb resulted in a dense corrosion product film.However,the corrosion resistance of LAZ832 needs to be further improved.Environmentally-friendly corrosion inhibitors sodium dodecyl benzene sulfonate?SDS?and sodium dodecyl benzene sulfonate?SDBS?were used as electrolyte additives for Mg-air batteries,which can effectively reduce the self-corrosion of magnesium anode and improve the specific capacity,and have no significant effect on battery voltage.The performance of SDBS was better than that of SDS.After the addition of1wt%SDBS in 3.5 wt.%NaCl aqueous solution,the specific capacity was increased from 637mA h g^-1 to 1032 mA h g^-1 at 1mA cm^-2.With the increase of discharge current density,the influence of SDS and SDBS on specific capacity was reduced.