Research On The Mechanism And Application Of Zinc Anode With Excellent Electrochemical Performance Induced By PAN-based Electrospinning Membrane

Aqueous zinc ion batteries（AZIBs）are considered to be one of the most promising next generation large-scale energy storage systems due to their abundant zinc（Zn）resources,environmentally friendly nature,and high level of safety.However,the issues of uncontrollable zinc dendrites,electrochemical hydrogen evolution（HER）,and corrosion side reactions of Zn anode pose significant obstacles to the practical applications of Zn anode and AZIBs.Constructing an artificial interface protection layer on Zn anode is an effective strategy to address the aforementioned issues and enhance the comprehensive electrochemical performance.This thesis constructs polyacrylonitrile（PAN）-based nanofiber membrane with"zincophilic-hydrophobic"properties on the surface of Zn sheet using electrospinning technology.The PAN-based layer can help to improve interfacial Zn²⁺transport behavior,prevent Zn corrosion and HER side reactions.Therefore,the high-performance Zn anode with the features of dendrite-free,corrosion-resistant and long-cycling life can be developed.The detailed research is shown as follows:1.The high-rate,dendrite-free Zn anode can be developed through constructing"zincophilic-hydrophobic"PAN-based nanofiber membrane interfacial protective layer.Through electrospinning technology,PAN and PAN/PMMA nanofiber membranes can be directly constructed on Zn anode.This PAN-based membrane can serve as the protective layer for Zn anode,and possess following several benefits.（1）PAN-based nanofiber membrane contains a large amount of non-polar carbon backbone structure,showing inherent hydrophobic properties.This hydrophobicity feature can be in favor of preventing Zn corrosion from the electrolyte and restraining the occurrence of HER side reactions.As a result,the cycling stability of Zn anode can be improved.（2）PAN-based nanofiber membranes possess electronegative functional groups（e.g.-COO-and-CN）which have strong adsorption effect with Zn²⁺.These electronegative functional groups can accelerate Zn²⁺de-solvation process.（3）Additionally,the uniform distribution of the zincophilic sites in PAN-based nanofiber membranes can help to create an even Zn deposition environment,which may effectively inhibit2D diffusion of Zn²⁺and promote the preferential deposition of Zn（002）crystal face.Compared with pure Zn anode,PAN@Zn and PAN/PMMA@Zn show comprehensive advantages including excellent corrosion-resistance,reduced HER side reactions,uniform and smooth Zn deposition.The PAN/PMMA@Zn-based symmetrical cell can cycle smoothly more than 800 h at 5 m A cm^-2.At a high current density of 10 m A cm^-2,it can work more than 2000 cycles.In addition,the full batteries assembled with PAN/PMMA@Zn andα-Mn O₂ also show good electrochemical performance.2.The high-rate Zn anode induced by MOF-808/PAN composite nanofiber membrane as protective layer.MOF-808/PAN@Zn can be obtained by constructing PAN-based nanofiber membranes on Zn sheet through in situ electrospinning process.This MOF-808/PAN@Zn shows following advantages:（1）Compared with MOF-808/PAN@Zn prepared by ordinary coating,the MOF-808/PAN@Zn constructed by electrospinning will exhibit better adaptability to volume change during Zn plating/stripping.（2）The MOF-808/PAN@Zn by electrospinning can not only preserve the“hydrophobic-zincophilic”property of PAN,but also present excellent Zn²⁺conductivity from MOF-808.As a result,the rate capability,corrosion-resistance,and HER inhibition effect of Zn anode can be improved after coating MOF-808/PAN electrospinning nanofiber membrane.Therefore,MOF-808/PAN@Zn by electrospinning shows better electrochemical performance(at 1 m A cm^-2,the MOF-808/PAN@Zn can work well more than 850 h with a low polarization potential of 35 m V).In addition,low voltage hysteresis（18.8 m V）is observed when switching the current density under 1-20 m A cm^-2.IThe MOF-808/PAN@Zn based symmetrical cell also can work well more than 1000 h at 20 m A cm^-2,indicating good rate capability.More importantly,the MOF-808/PAN@Zn//V₂O₅ battery can maintain a capacity of 95.6 m A h g^-1 after 2000 cycles at a current density of 2000 m A g^-1,and the capacity retention rate is about 99.8%.