Thermophysical Properties of Lithium Alloys for Thermal Batteries

Abstract

Thermal batteries are electrochemical systems primarily used in defense applications. The long-term storage capability afforded by the electrically inert low-temperature properties of the electrolyte-separator enables the use of this technology for military purposes. The current state-of-the art for thermal batteries relies upon the Li/FeS2 couple for power generation with the anode typically an Li–Si or Li–Al alloy. Thermal modeling of these primary battery systems is crucial to allowing the predictive capability of thermal evolution both in terms of the battery lifetime and thermal profile for the proper design of internal insulation and the surrounding environment. However, thermophysical properties for the anode alloys are not available in the literature. Thermophysical measurements of the alloys used in thermal batteries are essential for thermal modeling and simulation. The laser-flash method was used to determine the specific heat, thermal diffusivity, and thermal conductivity for Li–Si and Li–Al alloys as a function of temperature.