Competing Heat Carriers Leading to Distinctive Cation Concentration Dependent Thermal Conductivity of Amorphous Li<i><sub>x</sub></i>S (<i>x</i> = 0–2) Batteries
Yufei Gao, Hongzhao Fan, Yanguang Zhou, Ming Hu
Abstract
Abstract Thermal transport in amorphous lithium‐sulfur ( a ‐Li x S) 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 ‐Li x S changes largely by varying the concentration ( x ) of Li ions in a ‐Li x S. Interestingly, the TC of a ‐Li x S 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 ‐Li x S, 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 ‐Li x S structures, which is beneficial for the rational design of thermal management of Li‐S batteries.