A Study On The Mechanical Control And Performance Of Zinc Metal Anode

That aqueous zinc-ion batteriy(AZIB)have the advantages of safety,non-toxicity,low cost,and high ion conductivity makes it the next generation of large-scale energy storage system to replace lithium-ion batteries.In addition,zinc anode used in AZIBs is considered an ideal anode material due its high specific capacity,abundant reserves,low redox potential and so on.However,zinc anode still has some problems such as dendrite formation,corrosion passivation,hydrogen evolution,which seriously hinder its commercial application.Mechanical control modification is an ideal solution to the problems mentioned above as it is simple and effective which industrialization process requires to be.To our best of knowledge,zinc anode modification via mechanical control has not been reported yet.In this paper,we optimized zinc foil and current collectors(copper foil,copper foam)by various emerging mechanical methods.The effects of tensile deformation on crystallography,surface texture internal defects and further effects on zinc anode plating/striping behavior and the relative electrochemical performance were thoroughly studied.Details are as follow:(1)Increased the texture coefficient of(002)orientation and removed the passivation layer by tensile deformation.Stretched zinc foil leads to an in-plane growth of Zn(002)which results in a smooth and uniform texture,thereby arresting the propagation of dendrite.8%-Zn/8%-Zn(Zinc foil with 8%macroscopic strain)cells can cycle more than 800 hours at a current density of 5 mA cm^-2 and a capacity of 1 mA h cm^-2 with a very low polarization.Besides,8%-Zn/Mn O₂cells can maintain a capacity of up to 122.3 mA h g^-1(84.1%of the initial)at 1 A g^-1 even after500 cycles.(2)A certain degree of tensile deformation will alter dislocation density,and therefore the effect of deformation on zinc plating behavior were studied.Practical experiments show that dislocations can help mitigate the nuclei overpotential in substrate,which will help regulate zinc plating behavior.DFT calculation shows that the enhancement of zincphilicity can also be contributed to the increase of tensile deformation.The Coulombic Efficiency of 5%-Cu cells can maintain at over 99%after 500 cycles at a current density of 6 mA cm^-2 with a capacity of2 mAh cm^-2.We also find that anodes of 5%-Cu deposited with Zn show a homogenous morphology and an excellent electrochemical performance.(3)A three-dimensional Zn-Cu anode was synthesized by rolling commercial zinc foil and porous copper.Rolled Cu-Zn anode(RCZ)has two parts,the upper one of which is porous copper,and the bottom one is zinc loaded on the copper substrate.RCZ has an intrinsic merit-biface,which results in an ultralong lifespan for over 1800 hours at a current density of 1 mA cm^-2,and a unique self-optimized behavior which shows a reduced overpotential of 30 m V compared with the initial one(80 m V).Further investigations were conducted by means of three-electrode measurements and scanning electron microscopy(SEM).It was finally demonstrated that its extraordinary properties and self-optimized behavior can be ascribable to the evolution of interface and the abatement in overpotential of stripping.