Interface Engineering Assisting For High Stability Zinc Anode Plating/Stripping

Among various devices,lithium-ion batteries（LIBs）,which are widely used in consumer electronics and electric vehicles,dominate the rechargeable batteries market.Despite its commercial success,LIBs still encounter challenges with security,cost,and lithium resources.The safety problems of LIBs mainly come from flammable organic electrolytes and extremely active lithium metals.Compared with organic electrolyte batteries,aqueous batteries are easy to operate,can be assembled in the air,and have the advantages of non-toxicity and low cost.These advantages make aqueous batteries very promising for large^-scale power grids.Among them,the aqueous zinc anode battery has become a promising substitute for the traditional battery because of its high safety,large capacity and high cost performance.However,zinc anode still faces some problems such as dendrite formation,poor cycle life and low coulomb efficiency.These problems are largely related to the surface and interface characteristics of zinc anode,which greatly hinder the practical application of zinc anode in aqueous zinc-based batteries.Therefore,people are committed to the modification of zinc anode in order to eliminate the above problems.In this thesis,the interface structure design and component optimization were carried out on the surface of zinc anode electrode by in-situ methods,and the strategies such as zinc negative electrode interface modification or electrolyte optimization were used to improve the service life,mechanical stability and positive and negative electrode compatibility of zinc ion battery under high power density,which is of great significance for the future development of zinc based energy storage in water system.The details are as follows:（1）An in-situ solid electrolyte interphase（SEI）film is formed on the interface of electrode/electrolyte during the plating/stripping of zinc anodes by introducing trace amounts of multidentate ligand sodium diethyldithiocarbamate（DDTC）additive into 1 M Zn SO₄.The synergistic effect of in-situ SEI forming and chelate effect endows Zn²⁺with uniform and rapid interface^-diffusion kinetics against dendrite growth and surface side reactions.As a result,the Zn anode in 1 M Zn SO₄ electrolytes with DDTC additives displays an ultra-high coulombic efficiency of 99.5%and cycling stability（more than 2000 h）,especially at high current density(more than 600 cycles at 40 m A cm^-2).Moreover,the Zn||Mn O₂ full cells in the Zn SO₄electrolyte with DDTC additives exhibit outstanding cyclic stability（with 98.6%capacity retention after 2000 cycles at 10 C）.This electrode/electrolyte interfacial chemistry modulated strategy provides new insight into enhancing zinc anode stability for high performance aqueous zinc batteries.（2）A composite polymer interface layer is artificially self-assembled on the surface of the zinc anode by graft-modified fluorinated monomer（polyacrylic acid-2-（Trifluoromethyl）propenoic acid,PAA-TFPA）,on which an organic-inorganic hybrid（PAA-Zn/Zn F₂）solid electrolyte interface（SEI）with excellent ionic conductivity is formed by interacting with Zn²⁺Both the pouch cell and fiber zinc anode exhibit excellent plating/stripping reversibility after protecting by this organic-inorganic SEI,which can be stably cycled more than 3000 h in symmetric Zn||Zn cells or 550 h in fiber Zn||Zn cells.Additionally,this interface layer preserves zinc anode with excellent mechanical durability under various mechanical deformation（stably working for another 1200 h after bending 100 h）.The corresponding PAA-Zn/Zn F₂@Zn||Mn O₂ full cell displays an ultra-long lifespan（95%capacity retention after 3000cycles）and mechanical robustness（85%of the initial capacity for another 3000 cycles after bending 100 times）.More importantly,the as-assembled cells can easily power smart wearable devices to monitor the user’s health condition.The results offer a simple way to design flexible power sources for smart wearable electronics.（3）An aqueous hybrid battery composed of polyanionic-type cathode material（Na₃V₂（PO₄）₃,NVP）,Zn metal anode,and aqueous Ca²⁺/Zn²⁺hybrid electrolyte is successfully constructed.DFT calculation and experimental measurements show that Ca²⁺holds a diffusion barrier much lower than that of Zn²⁺in the NASICON structure,which makes it prior to Zn²⁺de/intercalation,to exert higher output voltage and better rate performance.More interestingly,the introduction of Ca²⁺synchronously inhibits the growth of zinc dendrite,endowing the cycling performance of the zinc anode in the Ca/Zn hybrid electrolyte with over twentyfold enhancement.This exciting combination gives full play to not only the excellent diffusion dynamics of Ca²⁺in the NASICON structure but also the electrostatic shielding effect of Ca²⁺with low reduction potential that inhibits the formation of zinc dendrites.As results,the NVP||Zn hybrid battery（Ca/Zn）delivers favorable specific capacity with outstanding rate performance(85.3 m Ah g^-1 capacity at 1 C,60.5 m Ah g^-1 capacity at 20 C),and excellent cycle stability（74%capacity retention after 1300 cycles）.This investigation achieved synergistic improvement of cathode/anode performance via electrolyte engineering,providing a new research approach to be compatible with of cathode and anode in aqueous zinc-based energy storage systems.