Regulate The Interface Stability Of Zinc Anode For Aqueous Zinc-ion Batteries

The depletion of fossil fuels and environmental degradation are two major daunting challenges facing humanity today.Developing advanced electrochemical energy storage devices to safely collect and store renewable,clean energy is considered crucial in addressing these issues.With advantages such as high energy and power density,long cycle life,and no memory effect,lithium-ion batteries（Li Bs）have taken a pivotal role in the field of electrochemical energy storage.However,the escalating manufacturing costs and the increasing concerns about the toxicity and flammability of organic electrolytes have prompted the search for low-cost and high-safety alternative energy storage technologies to meet the current energy demands.Since the emergence of aqueous batteries in 1994,these systems have demonstrated a broad application prospects in advanced large-scale grid energy storage systems and significant as potential competitors to Li Bs due to their operational safety,low manufacturing costs,environmental friendliness,and rapid charging capabilities.Among them,zinc（Zn）,characterized by high theoretical capacity(820 m A h g^-1),appropriate redox potential（-0.76 V vs.SHE）,excellent aqueous compatibility,and abundant resources,stands out as an ideal anode material in aqueous batteries.However,the practical application of aqueous zinc-ion batteries（AZi Bs）is hindered by certain issues associated with Zn anode.The root cause of these issues lies in the imbalance plating/stripping of Zn²⁺and the electrochemical instability of Zn anode interface.Specifically,Zn²⁺tends to deposit at specific sites,leading to dendrite formation,which can ultimately result in the short-circuits of batteries.Furthermore,in weakly acidic electrolytes,the hydrogen evolution（HER）and corrosion of Zn anode undermine the reversibility of cycling,inevitably reduces the performance of batteries.Both dendrite and side reactions are closely related to the interface stability of Zn anode.Therefore,this study addresses these challenges by focusing on regulating the interface stability of the Zn anode,aiming to regulate the deposition behavior of Zn²⁺on the Zn anode interface and mitigate the erosive effect of highly active H₂O molecules.These approachs ultimately alleviate the dendrite growth and side reaction occurrence.Consequently,a high stability and reversibility Zn anode was achieved,as well as extended cycle life and elevated Coulombic efficiency for AZi Bs.The main research results are obtained as follows:1.A Ni Co-LDH artificial coating was constructed on the Zn anode surface through a simple spin-coating method（NCLZn）,which effectively improved the stability of the Zn anode interface.The abundant metal sites and high specific surface area of Ni Co-LDH increase the deposition active site of Zn²⁺and the wettability of electrolyte,which not only reduces the interfacial resistance of batteries,but also promotes homogeneous deposition and reaction kinetics of Zn²⁺.The symmetric cells with NCLZn anode deliverers a stable cycle over 2500 h with a low overpotential of 20 m V at 1 m A cm^-2and 1 m A h cm^-2.The assembled NCLZn||Mn O₂ full cells achieves a discharge capacity of 153 m A h g^-1 after 1600 cycles at a current density of 1 A g^-1,much better than the Zn||Mn O₂ full cells(108 m A h g^-1).2.A low cost and recyclable I₂-assisted processing method was designed to in-situ fabricate a Zn O interface layer on the Zn anode（IAZO）at room temperature to effectively improved the stability of the Zn anode interface.This processing features an ultrafast synthesis time of only 5 minutes without posted annealing and the recovery rate of starting materials I₂ could be reache 66.75%.During the electrochemical cycling process,the IAZO anode promoted the desolvation of Zn²⁺and accelerated the reaction kinetics.Meantime,Zn O layer not only improves the uniform distribution of electric field and Zn²⁺flux at the Zn anode interface,but also inhibits the two-dimensional disordered diffusion of Zn²⁺due to the strong affinity with Zn²⁺,which is conducive to uniform deposition.The IAZO anode increases the cycle life of symmetrical cells to3100 h with an overpotential of only 14 m V.Simultaneously,a high Zn utilization rate of 52%is achieved at a high areal capacity of 30 m A h cm^-2,indicating the enhanced ability of inhibiting the dendritesand side reaction.The assembled IAZO||Mn O₂ full cells maintained a high discharge capacity of 152 m A h g^-1 after 1800 cycles with a capacity decay rate of only 0.004%.3.The 1,4-Butynediol（BYD）was employed as an electrolyte additive to reconstruct the electrical double layer（EDL）structure on the Zn anode surface.During the electrochemical cycling process,the BYD molecules substituted some H₂O molecules and adsorbed on the Zn anode surface to form a poor-H₂O EDL structure.On the one hand,the poor-H₂O EDL structure isolated the direct contact between H₂O molecules and Zn anode to mitigate hydrogen evolution and corrosion reactions.On the other hand,it promotes the ordered three-dimensional diffusion behavior of Zn²⁺as a“leveling agent”to inhibit the dendrite.Ultimately,the BYD molecules achieved a stable Zn anode interface,as well as the Zn||Zn symmetric cells deliverd a reversible cycle of 2700 h.4.We have introduced 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate（[EMIm]OTf）as a co-solvent to simultaneously regulating the diffusion of Zn²⁺on the Zn anode interface and the decomposition of active H₂O.In the optimized electrolyte,the EMIm⁺parasitic on the Zn anode to form an electrostatic shield layer and a hybrid organic/inorganic SEI to regulate the uniform deposition behavior of Zn²⁺.Meantime,the OTf^-parasitic in the solvent sheath of Zn²⁺,replacing some active H₂O to decrease the number,which is beneficial to improve the electrochemical window of electrolyte and regulate side reactions.The synergistic regulation of EMIm⁺and OTf^-effectively improved the stability of Zn anode interface.The improved electrolyte achieved a reversible cycle of 3,400 h for symmetric cells,much higher than the original electrolyte（280 h）.The assembled Zn||V₂O₅·2.2H₂O full cell has an ultra-high initial area capacity of 4.5 m A h cm^-2 and the longest cycle life of 25,000 cycles to date.