Synthesis And Performance Characterization Of Air Electrode For The Rechargable Zinc-Air Fuel Batteries

As a kind of green renewable energy,zinc-air fuel batteries have been paid more and more attention by electrochemical researchers due to its high specific power density(1086 W h kg-1)and reversible cycle performance.However,the slow reaction of oxygen in the cathode is still a main factor restricting the development of zinc-air fuel batteries.At the same time,a reasonable battery structure will greatly affect the charging-discharging performance of zinc-air batteries.This paper focuses on the design and improvement of zinc-air battery structure,the preparation of bi-functional catalyst and the design of an original air electrode structure.The concrete research content is as follows:(1)A zinc-air battery tests platform was firstly established to ensure the accuracy of the battery tests in this experiment.Through the simple control variable method,the basic factors affecting the battery performance are determined,and it is found that it conforms to the universal law of zinc-air battery tests:in discharging progress,narrowing the distance between positive and negative electrodes can reduce the battery internal resistance,thus it can improve the discharge performance.In a certain working range,using the same carbon paper as the air diffusion layer,the effect of the reactants at air electrode is only the concentration of oxygen,and the air mass does not have a great impact.During the optimization of charging-discharging test conditions,it is found that the charging-discharging performance and the battery stability can be improved by adding stainless steel mesh at air electrode.Besides,a self-made nickel foam air electrode has better stability than traditional air electrode,it provides an experimental idea for the following experiments.(2)We synthesized mesoporous Fe,Ni,S,N-homogeneous-doped carbon catalysts(Fe,Ni-SNC)by pyrolysis of polymerized ophenylenediamine(oPD).Silica colloid was used as the hard template to endow the porous structure in the synthesis.The porous Fe,Ni-SNC catalyst exhibits both high ORR and OER catalytic activity.The potential difference between ORR and OER is only 0.66 V,lower than that for commercial Pt/C and IrO2 catalysts.The Fe,Ni-SNC based rechargeable zinc-air battery exhibits high power density,high energy efficiency,and high durability.The high performance is attributed to the Fe,Ni bimetal doping and the N,S non-metal doping,which creates highly active catalytic sites.This bi-functional catalyst has potential application in the rechargeable zinc-air battery.(3)A hybrid zinc-air battery was assembled.We combined the F eCoNi-hydroxide catalysts in-suit grown on nickel foam by hydrothermal method as the oxygen evolution reaction(OER)catalysts and stability MnCoO/C catalysts for oxygen reduction reaction(ORR).The obtained rechargeable battery exhibited long-term stability and ultrahigh charge-discharge performance.After 500 hours working time at 10 mA/cm2,the discharging voltage was maintained at 1.13 V,and the charging voltage staid at 1.91 V with an ultralow charge-discharge potential gap of 0.78 V.This work provides a novel blue print of large-scale zinc-air batteries.