title: Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature.
abstract: The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion batteries for use in devices operating at elevated temperatures require thermally stable and non-flammable electrolytes. Ionic liquids (ILs), which are non-flammable, non-volatile, thermally stable molten salts, are an ideal replacement for flammable and low boiling point organic solvent electrolytes currently used today. We herein describe the procedures to: 1) synthesize mono- and di-phosphonium ionic liquids paired with chloride or bis(trifluoromethane)sulfonimide (TFSI) anions; 2) measure the thermal properties and stability of these ionic liquids by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); 3) measure the electrochemical properties of the ionic liquids by cyclic voltammetry (CV); 4) prepare electrolytes containing lithium bis(trifluoromethane)sulfonamide; 5) measure the conductivity of the electrolytes as a function of temperature; 6) assemble a coin cell battery with two of the electrolytes along with a Li metal anode and LiCoO2 cathode; and 7) evaluate battery performance at 100 °C. We additionally describe the challenges in execution as well as the insights gained from performing these experiments.
authors.affiliation: Department of Chemistry, Boston University.
authors.forename: Xinrong
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Chemistry, Boston University.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Chapman Varela
authors.affiliation: Department of Chemistry, Boston University; Department of Biomedical Engineering, Boston University; Department of Medicine, Boston University; mgrin@bu.edu.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Grinstaff
mesh_terms: D011211:Electric Power Supplies; D004573:Electrolytes; D006358:Hot Temperature; D052578:Ionic Liquids; D008094:Lithium
chemical_list: D004573:Electrolytes; D052578:Ionic Liquids; D008094:Lithium