Thermal transport of Li_3PS_4 solid electrolytes with ab initio accuracy
arxiv(2024)
摘要
The vast amount of computational studies on electrical conduction in solid
state electrolytes is not mirrored by comparable efforts addressing thermal
conduction, which has been scarcely investigated despite its relevance to
thermal management and (over)heating of batteries. The reason for this lies in
the complexity of the calculations: on one hand, the diffusion of ionic charge
carriers makes lattice methods formally unsuitable, due to the lack of
equilibrium atomic positions needed for normal-mode expansion. On the other
hand, the prohibitive cost of large-scale molecular dynamics (MD) simulations
of heat transport in large systems at ab initio levels has hindered
the use of MD-based methods. In this work, we leverage recently developed
machine-learning potentials targeting different ab initio functionals
(PBEsol, r^2SCAN, PBE0) and a state-of-the-art formulation of the Green-Kubo
theory of heat transport in multicomponent systems to compute the thermal
conductivity of a promising solid-state-electrolyte, Li_3PS_4, in all its
polymorphs (α, β and γ). By comparing MD estimates with
lattice methods on the low-temperature, non-diffusive γ-Li_3PS_4, we
highlight strong anharmonicities and negligible nuclear quantum effects, hence
further justifying MD-based methods even for non diffusive phases. Finally, for
the ion-conducting α and β phases, where the multicomponent
Green-Kubo MD approach is mandatory, our simulations indicate a weak
temperature dependence of the thermal conductivity, a glass-like behavior due
to the effective local disorder characterizing these Li-diffusing phases.
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