Application Of Tannic Acid And Phytic Acid In Passivation Protection Of Zinc Anobe Surface For Aqueous Zinc Ion Battery

With the continuous progress and development of society,more and more attention has been paid to energy issues.Traditional energy is non-renewable,and the combustion will bring environmental pollution,so it is urgent to develop clean renewable energy(electrochemical energy storage systems).In recent years,various types of metal ion rechargeable batteries,such as Li⁺,Na⁺,K⁺,Zn²⁺,Mg²⁺,Al³⁺,etc.,have studied extensively.Among them,metalic Zn is favored by people because of its unique characteristics,for example high theoretical capacity,low redox potential,high ionic conductivity in water,low cost,excellent safety performance,easy assembly,and abundant content in nature.However,aqueous Zn-ion batteries also suffer from certain defects,namely the growth of dendrites at the Zn anode and the occurrence of interfacial side reactions,which greatly hinder their practical applications.To address this issue,a solid-electrolyte interface(SEI)layer is constructed on the Zn anode to suppress dendrite growth and side reactions.In this paper,we chosed tannic acid and phytic acids as experimental subjects.Specially,phytic acid and tannic acid were dissolved in ethylene glycol dimethyl ether solution,and then added dropwise to the surface of the zinc anode.After sufficient contact,a dense SEI layer was formed on the surface of the zinc anode,which could inhibit the contact between aqueous electrolyte and anode surface,and promote uniform deposition of zinc ions.Then,the dendrites and side reactions were reduced,and the protective effect of the negative electrode was finally realized.(1)The zinc anode is treated with the ethylene glycol dimethyl ether solution of macromolecular tannic acid to form a passive film of zinc tannic acid on the surface of the zinc anode.The thickness of the zinc tannic acid film can be controlled by controlling the conditions,and the film has good uniformity and good bonding force with the surface of the zinc anode.And its unique Zn-O bond is beneficial to the affinity of Zn²⁺and the electrolyte,which is beneficial to the improvement of the efficiency of the deposition and dissolution process of zinc.The surface-treated Zn/Zn symmetric battery has a cycle life of 2300 h at a current density of 0.5 m A cm^-2 and a charge-discharge cycle time of2 h,which is nearly 8 times that of the untreated symmetric battery.The Zn/NH₄V₄O₁₀full cell has better cycling stability and Coulombic efficiency at a current density of 5m A mg^-1,and the treated Zn anode surface has fewer dendrites before and after cycling.(2)The zinc anode is treated with macromolecular organic phytic acid/DME solution,and a zinc phytate passivation layer is formed on the surface of the zinc anode to realize the protection of the zinc anode.Similar to tannic acid,phytic acid also has a strong chelating effect with zinc ions,and its unique cyclic structure is conducive to the formation of meshed microstructures and the desolvation process of zinc ions.Electrochemical tests prove that the symmetric battery after surface treatment can work stably for nearly 1900 h at a current density of 0.5 m A cm^-2 and a charge-discharge cycle time of 1 h,while the untreated life is only 122 h.The specific capacity of the full cell reaches 225 m Ah g^-1,which remains at 220 m Ah g^-1 after 300 cycles,which is also significantly better than that of the untreated battery;The coulombic efficiency of the surface-treated half-cell is stable within 100 cycles,which is also better than that of the untreated half-cell.