Modelling heat conduction in 3D composite cathode microstructures of all-solid-state batteries

Abstract

All-solid-state lithium batteries (ASSLBs) are a promising next generation energy storage technology comparing to conventional lithium-ion batteries (LIBs). Although ASSLBs have high thermal stability, thermal degradation and thermal runaway can still occur. The thermal characteristics of the cathode of ASSLBs play a crucial role in maintaining the stability of the interface with the electrolyte. It is important to understand the thermal characteristics of ASSLBs, which is highly associated with specific microstructure geometrics of composite cathodes. Here, this paper presents a 3D lattice Boltzmann heat conduction model to simulate the effective thermal conductivity (ETC) of the multiphase solid-state cathodes, which is composed of active material LCO (LiCoO₂) and solid electrolyte LLZO (Li₇La₃Zr₂O₁₂), generated using the discrete element method (DEM) with different porosities, volumetric ratios, particle size ratios, and various composite tortuosities. The findings indicate that porosity, volumetric fraction, and particle size all exert the decisive factor on ETC. Tortuosity emerges as a non-negligible factor influencing thermal conductivity, highlighting the importance of microstructural optimization.