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Studies of ionic liquids in lithium-ion battery test systems

Journal Article · · ECS Transactions
DOI:https://doi.org/10.1149/1.2209363· OSTI ID:908175
In this work, thermal and electrochemical properties of neat and mixed ionic liquid - lithium salt systems have been studied. The presence of a lithium salt causes both thermal and phase-behavior changes. Differential scanning calorimeter DSC and thermal gravimetric analysis TGA were used for thermal analysis for several imidazolium bis(trifluoromethylsulfonyl)imide, trifluoromethansulfonate, BF{sub 4}, and PF{sub 6} systems. Conductivities and diffusion coefficient have been measured for some selected systems. Chemical reactions in electrode - ionic liquid electrolyte interfaces were studied by interfacial impedance measurements. Lithium-lithium and lithium-carbon cells were studied at open circuit and a charged system. The ionic liquids studied include various imidazolium systems that are already known to be electrochemically unstable in the presence of lithium metal. In this work the development of interfacial resistance is shown in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell as well as results from some cycling experiments. As the ionic liquid reacts with the lithium electrode the interfacial resistance increases. The results show the magnitude of reactivity due to reduction of the ionic liquid electrolyte that eventually has a detrimental effect on battery performance.
Research Organization:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Organization:
USDOE Laboratory Directed Research andDevelopment
DOE Contract Number:
AC02-05CH11231
OSTI ID:
908175
Report Number(s):
LBNL--60630; BnR: YN0100000
Journal Information:
ECS Transactions, Journal Name: ECS Transactions Journal Issue: 26 Vol. 1
Country of Publication:
United States
Language:
English