Design And Performance Of Zinc Ion Battery Negative Electrode Based On Electrolyte Additive Control

With the increasing demand for large-scale energy storage,aqueous Zn-ion battery（ZIB）,as a representative of rechargeable multivalent ion battery,is considered as a potential substitute for Lithium-ion battery（LIB）.Aqueous Zn-ion batteries,which use a mild water electrolyte,are considered one of the most promising candidates for emerging energy storage systems（ESS）and portable electronics applications due to their environmental protection,safety,low cost and considerable energy density.ZIB has been widely studied in the academic circle,but its development is faced with the formation of zinc dendrite,hydrogen evolution reaction,corrosion passivation and other side reactions in the process of charge and discharge,which seriously affects the cyclic stability of ZIB.Therefore,the improved design and development of advanced negative electrode for aqueous Zinc-ion batteries is a key step in building future large-scale green energy conversion and storage systems.In this work,we mainly design and study the negative electrode of zinc ion battery through the method of electrolyte additive control.Firstly,by comparing the effects of different kinds of electrolyte additives,namely inorganic additive sodium bicarbonate（Na HCO₃）,zinc dihydrogen phosphate（Zn（H₂PO₄）₂）and organic additive cetyltrimethylammonium ammonium bromide（CTAB）on the cyclic stability of Zn//Zn symmetric batteries,the optimal additive and the optimal added solubility were analyzed.Then,on this basis,combined with interface impedance,interface polarization analysis and a series of electrochemical tests and material characterization to study the effect of the best additives on the negative electrode performance of aqueous zinc ion batteries.Finally,the electrolyte suitable for Zn//Mn O₂ full battery was prepared by using the best additive with the best added solubility,and the electrochemical tests were carried out on the electrolyte,such as cyclic voltammetry and rate performance,to study the effect of the additive on the practical application of the full battery.The experimental study found that,it was found that the symmetric batteries could cycle stably for 120 h under the 10 m M Na HCO₃ additive,while the symmetric batteries without additives could cycle for 59 h with voltage curve fluctuations and internal short circuit phenomenon by comparing the influence of the regulation of different electrolyte additives on the cycle stability of Zn//Zn symmetric batteries.In addition,when comparing the overvoltage of different additives in the initial cycle of symmetric battery,the experiment found that compared with Zn（H₂PO₄）₂ and CTAB sodium bicarbonate,it was more beneficial to reduce the overvoltage in the initial cycle,only 71 m V.In the study of the performance of sodium bicarbonate on zinc negative electrode,through the test and analysis of zinc negative electrode interface impedance,the addition of sodium bicarbonate reduces the impedance of zinc negative electrode by 150Ω,showing excellent interface transmission performance.At the same time,the polarization analysis of zinc anode found that Na HCO₃ can effectively induce the three-dimensional uniform deposition of zinc ions in zinc anode,which inhibited the side reaction of zinc dendrites.In addition,the addition of Na HCO₃ has certain optimization effect on increasing corrosion voltage and decreasing corrosion rate of zinc negative electrode interface in the study of polarization of zinc negative electrode.Finally,in the study of Zn//Mn O₂ full battery,it was found that Na HCO₃ played a positive effect on the redox peak,specific capacity,capacity retention and other properties of the full battery through the testing of cyclic voltammetry,multiplier performance and capacity retention rate.In terms of capacity retention rate,after 450 cycles,the capacity retention rate of the whole battery with sodium bicarbonate additive was 20%higher than that without additive.In a word,the results of experimental analysis show that 10 m M Na HCO₃ has certain optimization effect on the performance of symmetric battery and full battery.