Investigation of the 1-methyl-3-ethylimidazolium chloride-AlCl3/LiAlCl4 system for lithium battery application Part I: Physical properties and preliminary chronopotentiometric study

Abstract

The applicability of the 1-methyl-3-ethylimidazolium chloride - AlCl3 system for lithium battery application was investigated. Lithium chloride was found to dissolve up to 1.59 mole ratio of LiAlCl4/MeEtImAlCl4 upon reaction between LiCl and AlCl3 in the melt. Density, conductivity and viscosity of the melt upon addition of LiAlCl4 were determined. The density was found to increase monotonically from 1280 to 1480 kg m-3, while the conductivity decreased rapidly from the initial value of 5.6 mS to a steady plateau at 3.4 mS. The viscosity was varied from 1.46 Ns m-2 to a small but distinct initial fall prior to rising to 2.75 Ns m-2 when the mole ratio of LiAlCl4 increased from zero to 1.59. The chronopotentiometric studies indicate a satisfactory electrochemical behaviour with no apparent attack of the melt by the formation of the reactive lithium alloys. 350 cycles were achieved with cycling efficiency over 90% using an optimal c.d. of 6 mA cm-2 for lithium deposition on aluminium substrate in the melt. Prolonged cycling improved the nucleation rate but led to an increase in the internal resistance and a gradual reduction in the charge and discharge capacity. © 1993 Chapman & Hall.