Research On Construction Of Anode With High Performance And Its Energy Storage Characteristics For Rechargeable Zinc Air Battery

Rechargeable zinc-air battery has advantages of high energy density,low cost and good safety,and is one of the first choices in the field of energy storage in the future.However,zinc anodes face many problems such as dendrite growth,poor electrochemical reversibility under high-rate and large-capacity conditions,and short cycle life,which restrict commercial applications.To inhibit the growth of zinc dendrites and improve the electrochemical reversibility of zinc anode at high current and high capacity,in this paper,zinc anode deposition matrixs are prepared with etching the copper-zinc alloy mesh via a chemical etching method and an anodizing etching method,and with depositing Cu nanoparticles on the 3D nickel foam.The prepared zinc deposition matrixs are used as the anode current collectors,the nickel foam loaded with nano-Co_1.29Ni_1.71O₄ electrocatalyst is used as the cathode,and 0.2 M Zn O-added KOH aqueous solution is used as the electrolyte to configurate a rechargeable zinc air battery.Effect of the anode matrixs nanostructure on zinc deposition/dissolution is studied.Electrochemical performance of zinc anode is investigated.The copper-zinc alloy mesh is etched and modified by a phosphoric acid chemical etching method.The SEM characterization results show that clearer and deeper scratches appear along the axis of the copper wire after the surface of the copper mesh is etched at 70℃for 6 h compared to the copper mesh etched for 3 h.The anode matrix exhibits excellent charge-discharge rate performances with charge voltages of 1.9-2.0 V,a discharge voltage of 1.59 V,and charge-discharge coulombic efficiency of above 95%at a rate of 20 C.The current density is an important factor for electrochemical anodization and etching the obtained copper mesh surface exhibits pits with different sizes and depths along the axis of the copper wire.Zinc is mainly deposited in the form of dendrite on the the copper mesh electrochemically etched at the current density of 5 m A·cm^-2when charged.The deposited zinc mainly grows in the form of hexagonal prism zinc particles along the vertical substrate surface when the etching current density is increased to 10 m A·cm^-2.With the increases of the zinc deposition charging current density and the deposition time,a dense zinc deposition is obtained without any zinc dendrites.The dissolution of deposited zinc proceeds in layer-by-layer from the outer to the inner when discharged.A Cu/NF zinc anode matrix with nano-array structure is successfully constructed via electrodeposition of Cu nanoparticles on nickel foam.SEM characterization results show that the Cu nano-particle array structure on Cu/NF matrix has a template-like effect and can induce a well-ordered electrodeposition of zinc.After charging,zinc is densely deposited on the anode in the form of octahedral zinc nanocrystals and only a small amount of dendritic zinc with a broad-leaved grass-like structure exists on the surface.The zinc deposited on the anode is dissolved from the top layer to the bottom one by one during discharge.Cyclic voltammetry studies indicate that the Cu nanoparticle array structure improves the reversibility of zinc deposition/dissolution.Charge and discharge performance with large-capacity is significantly improved.the battery can cycle stably over 1700 charge and discharge cycles（about 1417h）with a coulomb efficiency of about 90%and the discharge voltage of around 1.69 V when charged and discharged at constant current density 10m A·cm^-2.long-cycle battery operation is realized.These results provide critical advances towards developing zinc-air batteries with potential high efficiency and long-term service life.