Competing Heat Carriers Leading to Distinctive Cation Concentration Dependent Thermal Conductivity of Amorphous LixS (x = 0–2) Batteries

Abstract

AbstractThermal transport in amorphous lithium‐sulfur (a‐LixS) is systematically investigated using molecular dynamics and the contributions from different types of heat carriers are quantitatively evaluated. In general, the thermal conductivity (TC) of a‐LixS changes largely by varying the concentration (x) of Li ions in a‐LixS. Interestingly, the TC of a‐LixS shows three distinct regimes of dependence on Li concentration. For low Li concentration (x = 0.4–1.2), the TC grows slowly, followed by a rapid increase in TC for medium Li concentration (x = 1.2–1.6), where the growth rate is three times that of the first regime, and finally, the TC is independent of Li concentration (x = 1.6–2.0). The TC enhancement in the first and second regimes is mainly attributed to propagating and non‐propagating vibrational modes in a‐LixS, respectively. In contrast, the stable thermal transport regime is governed by the competition between propagating and non‐propagating phonons. These investigations provide quantitative TC data of various polysulfides for shuttling analysis, and a fundamental understanding of the thermal transport mechanism of complex a‐LixS structures, which is beneficial for the rational design of thermal management of Li‐S batteries.