Study On Inhibiting Lithium Dendrites And Improving The Cycling Stability Of Lithium Anode

Energy has promoting the accelerating development of science and technology and improved the people's living standards around the world.However,with the expansion of industrialization,which will create severe environmental degradation,there has been the scarcity of natural resources,especially non-renewable energy sources,such as coal,oil and natural gas.Therefore,it has become a common goal of all circles to find cleaner,renewable and higher energy sources.With the gradual prosperity of the electric vehicle industry,the demand of battery energy density is getting higher and higher.Lithium-ion battery can't meet the demand of energy.Lithium metal is considered as the most ideal anode material for it's high special capacity and low potential.However,its application has not been realized.There are two main points:1.the volume expansion problem of lithium anode in the process of cyclic charging and discharging;2.the problem of dead lithium,namely lithium dendrite,which is formed in the process of cycling.It would pierce the diaphragm,which leads to short circuit,even explosion.Therefore,how to suppress lithium dendrites,which can be formed in the charging and discharging process of lithium metal batteries,as the same time,can maintain high coulomb efficiency has become a major research focus.Based on the research mentality,this paper carried out two experimental designs and research directions.The detailed conclusions are as follows:1.A new type of binary electrolyte,lithium bis(fluorosulfonyl)imide(LiFSI)/1,3-dioxane(1,3-DOL),was used to suppress the growth of lithium dendrites and stabilize the properties of lithium metal.The assembled battery of different concentrations of electrolyte was tested under galvanostatic current density.The experimental results showed that the Li/Li+battery was assembled with 2.5 M LiFSI/1,3-DOL electrolyte and polarized at a galvanostatic current density of 1 mA cm-2 and 0.5 mA cm-2,and the short-circuit onset-times are 72.3 hours and>190 hours.respectively.At this current density,the coulomb efficiency of lithium is 99.0%and 99.5%,respectively.This method can inhibit the growth of lithium dendrites effectively and achieve high coulomb efficiency.2.Gel polymer electrolyte can be obtained.The LiFSI is weighed and mixed with 1,3-DOL according to the volume ratio in the glove box.The test results showed that under 3.5 M gel polymer electrolyte,which could make the LMBs operate stably at the current density of 5 mA cm-2,the short circuit time measured at the current density of 1.0 mA cm-2 and 0.5 mA cm-2 are 60.3 h and 93 h,respectively.In the presence of LiFSI electrolyte,solvent 1,3-DOL will undergo ring opening polymerization and form polymer chain structure.This is also the reason for its formation of gel polymers,providing a reference for future research directions.