In-Situ Construction of Polyfurfuryl Alcohol SEI Film for Stabilizing Zinc Anode
Due to its advantages such as light weight,high energy density and long cycle life,lithium-ion batteries were successfully commercialized in the early 1990s and became the hottest and most widely studied battery.However,there were still many problems in lithium-ion batteries:(1)The electrolytes used in lithium0ion batteries were easy flammable and thus causing low safety;(2)Most or-ganic electrolytes were easily oxidized and sensitive to water when exposed to air,and had strict requirements for environmental condi-tions;(3)Lithium metal reserves were very low.Therefore,low-cost and high-safety aqueous rechargeable batteries had become one of the most potential replacements for lithium-ion batteries.Aqueous Zn-ion batteries(AZIBs)had the advantages of non-toxicity,safe-ty and environmental protections,and its energy density(5851 mAh·g-1)was comparable to lithium-ion batteries,and it had a high theoretical capacity(820 mAh·g-1)and a low electrochemical potential(-0.76 V(vs.SHE)),which made the researches of AZIBs very attractive,becoming one of the most studied aqueous batteries in recent years.However,zinc anode still faced many problems,among which the corrosion of zinc anode was a major problem in the application of AZIBs.Since the standard reduction potential of Zn/ZnO was-1.26 V and the standard reduction potential of hydrogen evolution was-0.83 V,the hydrogen evolution reaction was more likely to thermodynamically occur.Therefore,it was easy to accumulate a large amount of OH-on the zinc surface and react with the zinc surface to generate zinc oxide or zincate by-products,consuming the electrolyte and zinc anode,and reducing the capacity and utilization rate of active substances.To address these issues,researchers around the world had come up with a variety of strategies.Among them,in the surface coating protection strategy,the artificially constructed solid-liquid interface film(SEI film)on the surface of the zinc negative electrode could effectively isolate the contact between the water in the electrolyte and the surface of the zinc foil,thus inhibiting the corrosion of the zinc anode.Therefore,in this work,a dense artificial SEI film was constructed on the surface of zinc foil by the polymerization of furfuryl alcohol induced by oxalic acid.On the one hand,polyfurfuryl alcohol(PFA)coating could avoid direct contact between Zn2+and water molecules,inhibit the side reaction of hydrogen evolution,and improve the corrosion resis-tance of zinc anode.On the other hand,PFA coating contained rich oxygen-containing functional groups,which could improve the transport dynamics of Zn2+and induce the uniform deposition of Zn2+on zinc surface.When cycling at a current density of 1 mA·cm-2,Zn@PFA anode could cycle steadily for 553 h with an average coulomb efficiency of 99.9％.Moreover,the full battery with V2O5 posi-tive electrode could demonstrate a reversible capacity of 124 mAh·g-1at 1.0 A·g-1 after 300 cycles.
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