Study On Preparation And Properties Of Nano-composite Electrode For Zinc-air Battery

The issue of global warming and immense thrust of energy that is growingon day by day have forced to search new sustainable energies which can replacefossil fuels and nuclear energy. Various alternative energies such as hydrogenenergy, solar are already in practice, and some are in the phase ofcommercialization in new energy automobilies field. Metal-air batteries arewidely used because of its high energy density and safety. Among them, Zinc(Zn) is a promising anode candidate for secondary alkaline batteries because ofits abundance, relatively low cost, compatibility with aqueous electrolytes, andlow-toxic element. However, the dendrite, shape, change, self-corrosion,passivation of zinc anode and the high cost and scarcity of the precious metalsgreatly hinder the large scale implementation.In this paper, in order to solve these problems, nano material such carbonnanotube and silver nano-particles were added to the zinc anode and air cathode,respectively. The structure, morphology, wettability, corrosion resistance werestudied by XRD, FTIR, TG, Wetting and electrochemical test. (1) Carbon nanotube (CNT) are used to replace the acetylene black of zinccomposite anode. The results show that when the carbon nanotube reach8wt.%and16wt.%, the available zinc can reach44.94%and44.61%, respectively.(2) The electrode material particles are small and regular morphologybecause of the Mechanical action among acetylene black particles, sodiumcarboxymethyl cellulose, MnO2and zinc. Moreover, with the increase of carbonnanotube, large particles can be retained under the protection of carbonnanotube.(3) With the increase of carbon nanotube, the contact angle of waterdroplets on Zn-CNTs composite anode can decrease because ofmicro-nanometer dimensional network structure between the porous structuresurface of the Zn-CNTs composite zinc anode and C-O-C,C-C, C=O, CH, OH,NH,=C-O-C on the surface of carbon nanotube and acetylene black. The resultsshow that when the carbon nanotube reach8wt.%and20wt.%, the contactangle can reach30o below and20.5o, respectively.(4) With the increase of carbon nanotube, the capacitance of Zn-CNTscomposite anode can increase for the adsorption of carbon nanotube. when thecarbon nanotube reach16wt.%, reducation current can reach9.941mA and8.123mA at25℃and55℃, respectively. Moreover, reduction current can reach-12.028mA and-5.858mAat25℃and55℃, respectively.(5) With the increase of carbon nanotube, the corrosion resistance ofZn-CNTs composite anode can decrease for the adsorption of carbon nanotube. When the carbon nanotube reach16wt.%, self-corrosion current density andself-corrosion potential can reach4.17×10-9A·cm-2and-0.773V at25℃,respectively. Moreover, when the carbon nanotube reach12wt.%, self-corrosioncurrent density and self-corrosion potential can reach1.15×10-9A·cm-2and-0.085V at55℃, respectively.(6) Silver nano-particles (AgNPs) are used to replace the MnO2ofMnOx/AgNPs-CNTs composite cathode. The results show that when the AgNPsreach0wt.%, the cathode consist of MnO2, carbon nanotube, CMC and activatedcarbon. When the AgNPs reach2wt.%, the cathode consist of MnO2, Mn2O3,carbon nanotube, CMC and activated carbon. Moreover, when the AgNPs reach10wt.%, the cathode consist of AgNPs, carbon nanotube, CMC and activatedcarbon.(7) The electrode material particles are in various size when the AgNPsreach0wt.%. With the increase of AgNPs, silver nano-particles can be retainedin large size.(8) With the increase of AgNPs, the contact angle of water droplets onMnOx/AgNPs-CNTs composite cathode can reach30o below because ofmicro-nanometer dimensional network structure between the porous structuresurface of the composite zinc anode and C-O-C,C-C, C=O, CH, OH, NH,=C-O-C on the surface of carbon nanotubes and activated carbon. The resultsshow that whenAgNPs reach8wt.%, the contact angle can reach8o below. (9) With the increase of AgNPs, the capacitance of MnOx/AgNPs-CNTscomposite cathode can decrease because of the hydrogen spillover effect. whenAgNPs reach2wt.%and6wt.%, reducation current can reach8.132mA and5.506mA at25℃and55℃, respectively. Moreover, reduction current can reach-5.349mAand-4.028mAat25℃and55℃, respectively.(10) With the increase of AgNPs, the corrosion resistance ofMnOx/AgNPs-CNTs composite cathode can decrease for electrocatalyticproperties of AgNPs. When the AgNPs reach2wt.%, self-corrosion currentdensity can reach6.35×10-8A·cm-2and7.02×10-7A·cm-2at25℃and55℃,respectively. Moreover, self-corrosion potential can reach-0.275V and-0.285Vat25℃and55℃, respectively.