Functional Design And Performance Investigate Of Dendrite-free Metal Anode For Aqueous Zinc-ion Batteries

Continued consumption of fossil energy has brought about problems such as environmental pollution and climate warming.In order to successfully achieve the“double carbon”strategic goal,it is necessary to build an efficient energy storage system with new energy.Since the arrival of the lithium-ion battery（LIB）,it has been extensively used in electronics and electric vehicles due to high energy and power density.However,the shortage of raw materials and high prices have become increasingly prominent.In particular,the organic electrolyte is toxic and flammable,and there are great potential safety hazards.Consequently,it is imperative to develop a new type of secondary battery technology at low cost,high efficiency and security.Aqueous batteries have received extensive attention due to the environmental friendliness and high safety of water-based electrolytes.Among them,aqueous zinc-ion batteries（AZIBs）differ in low cost,high safety and power density.However,the zinc anode is confronted with problems such as hydrogen evolution,corrosion and dendrite growth caused by uneven ion concentration.All these elements cause low coulombic efficiency,poor cycle stability,even short circuit of the battery,which limits the development and application of zinc-ion batteries.In view of the above problems,this thesis takes zinc metal anode as the research object,and optimizes the interface ions from the two different dimensions of“addition”and“subtraction”.The protective coating on the surface of Zn and the intrinsic functional structure of Zn are designed,and a series of anodes with excellent performance are obtained.On this basis,they are matched with the manganese dioxide cathode material to assemble full battery to verify the potential of the functionalized anode in the practical application process.The research conclusions are listed as follows.Firstly,in order to solve the problem of dendrite growth caused by uneven ion distribution of ions at the interface,an artificial protective layer of Na₅YSi₄O₁₂ is constructed on the surface of zinc anode.Benefiting from the high ionic conductivity and low electronic conductivity of Na₅YSi₄O₁₂,the protective layer optimizes the transport of zinc-ions and effectively promotes the uniform deposition of Zn,thereby inhibiting the growth of dendrites.At the same time,Na₅YSi₄O₁₂ with excellent electrochemical stability is used as the physical protection layer of zinc anode to enhance the corrosion resistance of metal surface,thus weakening the corrosion and passivation side reactions.In addition,by adjusting the thickness of the protective layer,the modified zinc anode achieves a stable cycle of more than 1000 h at a current density of 1 m A cm^-2,and the full cell assembled with Mn O₂ maintains a discharge specific capacity of 183.39 m Ah g^-1 after 660 cycles at a current density of 1 A g^-1,showing excellent electrochemical performance and high stability.Subsequently,to further optimize ion distribution,a super-hydrophilic zinc anode is prepared by designing the intrinsic structure of zinc metal.Super-hydrophilic zinc anodes are obtained by scanning zinc metal with femtosecond laser filaments of different energies.And the complete infiltration with the electrolyte increases the flux of zinc-ions,realizes the uniform regulation of the ion field,and inhibits the growth of dendrites.Meantime,the well-shaped grooves generated by filament processing greatly increase the contact area at the interface,reduce the local current density,and effectively inhibit the growth of zinc dendrites and the occurrence of side reactions.Furthermore,the（002）crystal plane of Zn is more exposed after laser filament processing,which adjusts the morphology of Zn more inclined to parallel deposition,so that the anode exhibits excellent cycle performance.Under a capacity of 1 m Ah cm^-2,the electrode demonstrated an ultra-long stable cycle of more than 2000 h.At a current density of 1A g^-1,the full cell assembled with Mn O₂ can still maintain a high specific capacity of123.47 m Ah g^-1 after 1282 cycles,and the coulombic efficiency is as high as 99.72%.In this thesis,in order to solve the problem of uneven ion field at the interface between zinc metal anode and electrolyte,the cycle stability and electrochemical performance of the electrode are optimized by constructing artificial protective layer and laser filament processing zinc anode respectively.Combined with a variety of tests,the effects of functionalized anodes on zinc dendrites and side reactions are systematically explored,and the optimized anodes are also applied to full batteries,which provide research basis and experimental basis for the construction of new high-performance anodes for subsequent aqueous zinc-ion batteries.