Wetting Behavior of Dialkylimidazolium Chloroaluminate, a Room Temperature Molten Salt

摘要

The wetting behavior of a battery electrolyte can have a dramatic effect on the internal resistance of the battery as well as its cycle life. Good wetting of battery separators by electrolyte is essential for easy passage of ions through the separator pores during charge and discharge. Porous, gas diffusion electrodes require, on the other hand, a lesser degree of electrolyte wetting, so that the line of contact of three phases (reactive gas/liquid electrolyte/porous electrode or current collector) can be maintained within the porous electrode through a balance of capillary and hydrostatic pressures. Advancing and receding contact angles were determined for diakylimidazolium chloroaluminate, room-temperature molten salts on various candidate battery separator and porous electrode materials. The wetting angles were determined for the binary 1-methyl-3-ethylimidazolium chloride/aluminum chloride melt as a function of such variables as composition, chlorination of the imidazolium ion, replacement of AlCl3 by LiCl, solid porosity, and solid surface cleaning procedure. In nearly all cases involving AlCl3 as a second component, the melt easily wets the substrate.