Electrodeposition Behavior And Electrochemical Properties Of Zinc Metal Anodes

Aqueous zinc-ion batteries have great potential for large-scale energy storage due to their environmental benignity,safety,and low cost.Zinc metal is the preferred anode material for zinc-ion batteries,and its cycle stability has an important impact on the performance of the full battery.The development of zinc-ion batteries is still greatly limited by the problem of zinc dendrites.Therefore,in-depth analysis of the formation causes of Zn dendrites and the design of dendrite-free Zn metal anodes are of great significance to promote the commercialization of Zn-ion batteries.In this thesis,the effects of crystal facets orientation and metal affinity on zinc electrodeposition behavior were explored from the perspectives of current collectors and protective layers,and several highly stable zinc metal anodes were developed.The specific work is shown as follows:（1）The selective deposition of zinc on the randomly oriented copper foils was observed by optical microscopy and electron backscattering techniques,and the results indicated that the zinc deposition activity of Cu（1 1 2）and（1 2 3）facets was lower than the Cu（0 1 2）facet.Further,theoretical simulation demonstrated that the uneven distribution of electric field caused by the difference of crystal plane orientation was an important reason for the formation of zinc dendrites.Herein,a simple stress annealing and electroless tin plating method was used to prepare（100）fully preferred copper foils and copper-supported（101）fully preferred tin interface layer.Owing to the uniform Zn deposition activity and high zincophilicity of the Sn layer,the modified Cu foil exhibits highly reversible Zn deposition/stripping behavior and dense Zn deposition morphology.（2）It was found that commercial barium titanate has intrinsically zincphobicity by DFT calculation,and a nano-porous barium titanate protective layer was prepared on zinc foil by a simple blade coating method.Benefiting from the role of the protective layer in regulating the interfacial zinc ion distribution and ion transport flux,and preventing zinc from piercing the membrane,the zinc anode modified by the protective layer exhibits excellent zinc deposition/stripping reversibility at 0.5 m A cm^-2 for 0.5 m A h cm^-2,long cycle life（840 h）and low voltage hysteresis（36 mV）.This work provides a novel guiding direction for discovering naturally zincophobic protective layer materials to modify zinc anode interface,which can be also extended to other metal anodes.