In-Situ Construction Of Protective Interface On Zinc Metal Anode For Aqueous Zinc Ion Batteries

With the rapid development of the global economy,the demand for fossil energy has increased exponentially.However,as a primary energy source,fossil fuels have many drawbacks,including being non-renewable,causing serious pollution to the environment,and limited resources.Therefore,finding sustainable and renewable energy sources such as solar energy and wind energy has become increasingly urgent.In recent years,renewable energy sources have been widely used and the demand for energy storage devices has also increased.As the most widely circulated energy storage devices,lithium-ion batteries have undergone rapid development and process a complete industrial chain.Nonetheless,there are many problems with lithium-ion batteries,including limited lithium resources,toxic electrolyte,and poor safety,all of which limit their further advancement.Aqueous zinc-ion batteries have emerged as promising next generation energy storage devices due to the abundance of zinc,high safety,high specific capacity,non-toxic and non-hazardous.However,dendrite growth and side reactions on the zinc anode seriously compromise the cycle life,thereby slowing their development progress.The construction of zinc metal anode interface can realize the improvement of aqueous zinc ion battery performance.Compared with the complicated and uncontrollable ex-situ construction strategy,in-situ construction has been widely studied for its simplicity and convenience and its more stable interface.The main principle involves the in-situ treatment to form a dense protective interface or a special morphology on the electrode surface to regulate the electrochemical process of zinc ions on the electrode surface,thereby achieving uniform electrodeposition and stripping of zinc ions and extending the cycle life of aqueous zinc-ion batteries.This thesis achieves long-life aqueous zinc-ion batteries by pretreating zinc metal electrodes with In F₃ or Sb F₃,The research content is as follows.（1）Dipping the bare zinc foil into DMSO solution of In F₃ and a multifunctional protective interface forms on the electrode surface,which consists of zinc ion conductor Zn F₂ and zincophilic In-O-F.On the one hand,this hybrid protective layer guides the uniform deposition of zinc ions on the electrode surface and suppresses the hydrogen production;on the other hand,it can greatly inhibit the formation of by-products Zn₄SO₄（OH）₆·5H₂O and the vanadium dissolution.The synergistic effects realize a high-performance aqueous zinc-ion battery.The symmetric cell exhibits a long life of 3200cycles at 20 m A cm^-2,as well as a coulombic efficiency（CE）of Zn plating/stripping as high as 99.9%after 2200 cycles at 2 m A cm^-2.The full cells coupled with Mn O₂ and V₂O₃cathodes also demonstrate excellent electrochemical performances.Therefore,the pretreatment of zinc electrodes with In F₃ provides a simple and effective strategy for the development of aqueous zinc-ion batteries.（2）The bare zinc foil was immersed in Sb F₃ aqueous solution for pretreatment,and a spherical-like nanoparticle arrays protective layer is constructed on the electrode surface.The deposition of zinc ions preferentially occurs on this protective layer,and the spherical structure increases the nucleation sites of zinc ions and guides the uniform plating/stripping process of zinc ions,so that the deposition of zinc ions spread over the whole electrode surface.At the same time,the presence of the protective layer greatly improves the stability of the electrode in the electrolyte,resulting in a positively shifted corrosion potential and a smaller corrosion current density.The symmetric cell achieved a stable cycling of 1490cycles at a small current density of 1.0 m A cm^-2 and 7200 cycles at a high current density of 10.0 m A cm^-2.When matched with Mn O₂,the full cell also exhibits superior multiplier performance and higher capacity retention after long cycling.