Thermally-responsive, nonflammable phosphonium ionic liquid electrolytes for lithium metal batteries: operating at 100 degrees celsiusElectronic supplementary information (ESI) available: Detailed ionic liquids synthesis, characterization, conductivity, cyclic voltammetry, battery cycling and those of other compositions; SEM images; energy density calculation. See DOI: 10.1039/c5sc01518a

• Main Authors: Lin, X, Kavian, R, Lu, Y, Hu, Q, Shao-Horn, Y, Grinstaff, M. W
• Format: Journal Article
• Language: English
• Published: 13.10.2015
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c5sc01518a

Rechargeable batteries such as Li ion/Li metal batteries are widely used in the electronics market but the chemical instability of the electrolyte limits their use in more demanding environmental conditions such as in automotive, oil exploration, or mining applications. In this study, a series of alkyl phosphonium ionic liquid electrolyte are described with high thermal stability and solubility for LiTFSI. A lithium metal battery (LMB) containing a tailored phosphonium ionic liquid/LiTFSI electrolyte operates at 100 °C with good specific capacities and cycling stability. Substantial capacity is maintained during 70 cycles or 30 days. Instant on-off battery operation is realized via the significant temperature dependence of the electrolyte material, demonstrating the robustness and potential for use at high temperature. Lithium metal battery cycling at 100 °C is enabled by thermally-responsive, nonflammable phosphonium ionic liquid electrolytes.