Investigation Of Some Key Materials Of Zn-Air Battery And A Novel Porous Electronic Conducting Ceramics Loaded With Silver Nanoparticles As Cathode

Zinc-air battery is a relatively mature technology in all metal-air batteries.It has low cost,a high theoretical specific energy density(1086 Wh·kg^-1)and is environmentally friendly.Consequently,with steady working voltage,the commercial product of zinc-air battery has been widely used in radio communication,railway signal and hearing aid,which just need low output power（<10mW）.What’s more,zinc-air battery has been gradually applied to the energy storage industry,the electric vehicle and the portable electronic equipment.The research content of this paper is carried out around the three key components of the zinc-air battery:the separator,the anode and the cathode.This paper studies the effects of different separators on the electrochemical performance of zinc-air battery.Respectively,tablet pressed with Zn powder and Zn plate are used as anode to assemble the zinc-air batteries,and the effects of the morphology of the discharge products on the utilization of the zinc anode are investigated.Moreover,for the first time,the zinc-air battery uses a novel air electrode that a porous perovskite ceramic La_0.7Sr_0.3CoO_3-δ（LSC）with Ag nanoparticles directly grown on.The porous LSC is used as substrate while the Ag is used as catalyst for oxygen reduction reaction.The porous structure of substrate is so important that it decides the amount and dispersion of Ag nanoparticles which affecting the electrochemical performance of air electrode.Microfiber glass separator has fiber-rich and porous structure,thickness of 0.7mm,and its absorption of KOH solution is three times the rate of nonwoven separator.Zinc-air battery assembled with microfiber glass separator has an open circuit voltage of 1.5V,and stable discharging voltage.What’s more,the low utilization of zinc anode can be caused by different reasons when using different zinc anodes.After the batteries discharging,the surface of zinc plate is covered by dense moss-like ZnO,which hinders the further oxidation of internal zinc,thereby reducing the utilization of zinc anode.On the other hand,after the batteries discharging,on the surface of tablet pressed with Zn powder,there are lots of small-needle-like ZnO,making a loose and porous structure,good for the oxidation of zinc inside.However,because of high specific surface area of zinc powder,a part of zinc is oxidized directly without discharging,which reduces the utilization of zinc anode.In addition,if the zinc electrode is directly exposed to the Cu foil as current conductor,it will accelerate the self-corrosion of zinc and reduce the utilization of zinc anode.Based on the study of these two key components,microfiber glass separator,zinc powder and novel Ag-LSC porous ceramic cathode are assembled together into zinc-air battery.Experimental results show that the Ag-LSC electrode,with a porosity of³2%and a Ag load of³0 mg·cm^-2,has the best performance in all tested samples,and a zinc-air battery with such air electrode gives a maximum power density of 141 mW·cm^-2.What’s more,in order to ensure the gas diffusion channels,the hydrophilicity and hydrophobicity of the cathode is modified to prevent flooding.After all that,the life-time of the zinc-air battery,with optimization by adding PTFE as hydrophobic agent to its selected Ag-LSC electrode,increases significantly.