Investigation On The Properties Of Electrolyte Of Lithium Bis(fluorosulfonyl) Imide-ultrahigh Concentration Either Electrolyte

In recent years,with the rapid development of electric vehicles and large-scale energy storage power grids,lithium-ion batteries（LIBs）based on the intercalation electrode are hard to meet the application requirements of the high-energy density.Thus,the research of lithium（Li）metal batteries（LMBs）is on the agenda,once again.Li metal has been studied as an anode electrode for rechargeable Li metal batteries（LMBs）worldwide,by virtue of its low molecular weight(6.94 g mol^-1),the lowest negative electrochemical potential（-3.045 V vs.SHE）,and extremely high theoretical specific capacity(3860 mAh g^-1),and all of these lead to the improvement of the energy density.However,the key problems hindering the development of Li metal batteries are lithiumdendritic growth and safety concern among the cell cycles.To solve the issues above,great efforts have been made worldwide.Recently,high concentration Li salt electrolytes have been suggested as a approach for effectively suppressing lithiumdendritic growth.In this work,we prepare a series of concentration electrolyte of LiFSI-DOL/DME+0.1 wt%TBA.In the electrolyte,Lithium bis（fluorosulfony）imide（LiFSI）is conductive salt.And 1,3-dioxolane（DOL）and glycol dimethyl ether（DME）with a mixture of volume ratio 1:1 is the solvent.And also,TBA is addictive.And all of these make up Mixture Ether Solvent,MES.Firstly,the physicochemical and electrochemical properties of these series of electrolytes in various concentration（1 mol Li FSI in per liter MES,3 mol Li FSI in per liter MES,8 mol LiFSI in per liter MES and 12 mol LiFSI in per liter MES）were characterized,such as thermodynamic stability,thermal phase transformation,viscosity,Li-ion transference number,oxidation potential,lithium deposition and corrosion of aluminum foil,the stability of metallic lithium and cycle efficiency test,etc.The results show that the electrolyte of this series can meet the basic requirements of the liquid electrolyte.Secondly,the applicability of these electrolytes in Li metal batteriesis evaluated preliminarily,with assembling the cell of Li|Cu and Li|Li.And the results indicate that the ultra high concentration electrolyte（12 mol LiFSI in per liter MES）has the largest lithium ion migration number(t⁺_Li:0.68)and high coulomb efficiency（average coulomb efficiency>99%）and long metal lithium symmetric battery cycle stability（>600 h）in the present work.And all of these may attributed to ultra high concentration electrolyte greatly improve the regularity of lithium deposition/dissolution in the cycle of lithium metal secondary battery,which is beneficial to inhibit the growth of lithium dendrite.