Thermal comparator measurements on dimethyl sulfite

Abstract

The thermal conductivity of the organic dimethyl sulfite is of interest because of its potential use as a nonaqueous battery solvent owing to its stability with high-energy density electrodes and its ability to dissolve electrolytes (2, 8). Yao et al. ( 9 ) have measured the melting point (14loC), the dielectric constant (623.3 = 22.5), and the viscosity (0.7715 CP at 3OoC and 0.4361 CP at 8OOC). Kyrides (4 ) has reported a boiling point of 126OC at 760 mm Hg and 52OC at 45 mm Hg, a density of 1.2073 glcc at 24OC, and an index of refraction of 1.4093 at 2OoC for dimethyl sulfite. An exchange current density of 15 mA cm-2 for a 1.12 M LiC104 solution in dimethyl sulfite has been found by Tiedemann and Bennion (8). Mahefkey and Kreitman have noted that the important thermal related properties of battery performance, viz., cell cycle life and cell capacity, as well as electrical efficiency, can be strengthened by operation at lower battery temperatures which they achieved with the introduction of an intercell heat pipe (5). The removal of waste heat from a battery is an important design characteristic; therefore, the thermal conductivity of the electrolyte solution is a significant factor in the design and operation of a battery. However, very little information exists on the thermal properties of dimethyl sulfite. To help fill this gap, we have used a thermal comparator to carry out measurements on the room temperature thermal conductivity of the liquid. The thermal comparator method for obtaining rapid thermal conductivity measurements on solids was introduced by Powell (6) in 1957. Subsequent modifications (7) have led to the development of a commercial unit (available from the Thermophysical Properties Research Center, Purdue University Research Park, 2595 Yeager Road, W. LaFayette, Ind. 47906), a prototype of which was used in the measurements reported below. The purpose of this paper is to report the thermal conductivity measurement of dimethyl sulfite and to comment on the application of the comparator to the measurement of the thermal conductivity of liquids.