(535g) Electrochemical Control and Modulation of the Flammability of Ionic Liquid Fuels

Flammability and combustion of high energy density liquid propellants are controlled by their volatility. We demonstrate a new concept through which the volatility of a high energy density liquid propellant can be dynamically manipulated enabling one to (a) store a thermally insensitive oxidation resistant non-flammable fuel (b) generate flammable vapor phase species electrochemically by applying a direct-current voltage bias and (c) extinguishing its flame by removing the voltage bias, which stops its volatilization. We show that a thermally stable imidazolium-based energy dense fuel, can be made flammable or non-flammable simply by application or withdrawal of a direct-current bias. This cycle can be repeated as often as desired. In-situ mass spectrometry is used to characterize what species are volatilized during electrolysis. To explore the role of anion we employ 5 different species and show that the rate of electrochemical reaction scales with ion conductivity implying this is a mass transfer controlled process. The estimated energy penalty of the electrochemical activation process is only ~ 4% of the total energy release. This approach presents a paradigm shift, offering the potential to make a ‘safe fuel’ or alternatively a simple electrochemically driven fuel metering scheme.