Atomistic insights into the thermal transport properties of inorganic components of solid electrolyte interphase (SEI) in lithium-ion batteries

The thermal behavior during operation of Lithium-ion batteries (LIBs) is widely concerned with respect to their electrochemical performance and safety. The solid electrolyte interphase (SEI) is a critical layer formed during electrochemical reactions in LIBs. A thorough understanding of SEI's thermal transport properties is essential to identify limitations within the internal heat transfer of LIBs. In this work, a computational study of the thermal transport through SEI was performed based on classical molecular dynamics (MD) simulations. Three representative inorganic components of SEI, namely Li2CO3, Li2O and LiF, were explored. First, the force fields were evaluated for accurate MD simulations. Subsequently, the impact of structural properties and temperatures on the thermal conductivities of SEI were investigated, followed by discussion on radial distribution functions and vibrational density of states. It was found that the comparison of thermal conductivity of the ordered crystals is Li2O > LiF > Li2CO3. As temperature increases, the thermal conductivity of inorganic components decreases significantly. Additionally, it was discovered that the thermal conductivity of amorphous compounds is notably lower than that of ideal crystals and is closely related to the molar ratio of inorganic components. The results of this work can help understand the thermal transport properties of SEI and offer valuable insights for the design of electrolytes and SEI toward improving the thermal safety performance of LIBs.