Study On Modification Of Metal Zinc Anode Of Zinc-ion Battery And Its Eiectrochemical Perfornance

With the depletion of traditional fossil energy and related environmental problems,the demand for renewable energy has become more and more urgent.Extensive research has been conducted on rechargeable batteries based on multivalent metal ions,including Zn²⁺,Ca²⁺,Mg²⁺and Al³⁺ions.The unique advantages of metallic zinc have inspired people’s enthusiasm for zinc ion batteries（ZIBs）,such as high theoretical capacity(820m Ah g^-1 and 5855 m Ah cm^-3),low redox potential（0.76 V for standard hydrogen electrodes）,and high storage capacity（About 300 times that of lithium）,and good inertness in oxygen and humid atmosphere,higher hydrogen release potential,so it can effectively inhibit the progress of side reactions.However,there are still many urgrnt problems in water-system ZIBs,which limit their further applications.Among them,electrolyte additives play an important role in solving these problems.Many additives（such as ionic,organic,inorganic additives）have been used in zinc anodes to control the surface morphology of zinc and inhibit side reactions such as zinc dendrite growth,hydrogen evolution reaction,and zinc surface corrosion and passivation.With these additives,significant results have been achieved in protecting the negative electrode and optimizing the overall performance of the battery.This article starts with industrial chemical plating,finds electrolyte additives suitable for water-system ZIBs from the currently widely used additives,and analyzes its principle of action from a deep level.It mainly studies two electrolyte additives,saccharin and CF₃SO₃Li.The specific research content carried out is as follows:（1）From the commonly used additives in industrial zinc plating,considering the structure and quantity,four substances of gum arabic,gelatin,dextrin and saccharin were selected for the experiment,and then the electrodeposition experiment was carried out to compare the deposition morphology of zinc.Later,saccharin was chosen as an additive.And according to the immersion experiment of the electrode sheet,the optimal additive concentration was determined.After adding saccharin,the cycle life of the Zn-Zn half-cell is prolonged by more than 200 hours under the conditions of a current density of 0.5 m A cm^-2 and a charge and discharge time of 2 hours.The current density is 2 m A cm^-2.,The charging and discharging time is 0.5 hours each,it has been significantly improved for more than 100 hours;the coulombic efficiency and cycle stability of Zn-Ti for battery deposition and dissolution have been significantly improved,and the cycle life has increased from more than 20 hours to more than 200hours;the full battery can still be maintained at about 90%after 1000 cycles at a high current density of 5 A g^-1,which reflects its excellent cycle stability.Our research work has developed a new type of electrolyte additive,which provides a new way for the research of water-based ZIBs zinc anode protection（2）Introduce（CF₃SO₃）^- into the zinc sulfate electrolyte,and use the principle that（CF₃SO₃）^-in water is easier to combine with Zn²⁺to weaken and affect the desolvation process of zinc ions,thereby inhibiting zinc growth of negative pole dendrites.The results of the electrodeposition experiment confirmed our guess,and then we conducted more detailed and specific electrochemical tests to characterize the properties of lithium triflate electrolyte from multiple aspects.After the addition of CF₃SO₃Li,the cycle life of the Zn-Zn half-cell is extended by more than 100 hours under the conditions of a current density of 0.5 m A cm^-2 and a charge and discharge time of 2 hours.Under the conditions of 2 m A cm^-2 and 0.5 hours of charge and discharge time,it has also been significantly improved for nearly 160 hours;the coulombic efficiency and cycle stability of Zn-Ti for battery deposition and dissolution have been significantly improved,and the cycle life has been increased from 20 to 300 hours;after 1000 cycles of the full battery with the optimal concentration of 5 A g^-1 at a high current density,there is almost no loss of capacity,which reflects its excellent cycle stability.Our research work has developed a new type of electrolyte additive,which adds new possibilities to inhibit the growth of zinc dendrites and extend the life of water-based ZIBs.