Predicting specific heat capacity and directional thermal conductivities of cylindrical lithium-ion batteries: A combined experimental and simulation framework

Abstract

This paper proposes a methodology to determine the specific heat capacity and the directional components of the thermal conductivity of cylindrical lithium-ion batteries (LIBs) by combining numerical simulations with experimental measurements. These thermophysical properties are crucial for the modeling and simulation of LIBs, and for assessing the performance of battery thermal management systems. The heat capacity of LIBs can be obtained directly with an isothermal battery calorimeter or can be estimated indirectly as a weighted sum of the heat capacities of its constituent materials. However, calorimeters are expensive, and materials compositions are typically not disclosed by LIB manufacturers. In this paper, we propose a cost-effective methodology that uses conventional experimental measurements of battery operating voltage and transient surface temperatures at multiple battery locations to predict the heat generation with a single-particle electrochemical model and the thermophysical properties with an inverse thermal simulation. To assess the accuracy of the proposed methodology, these thermophysical properties are then used to predict the battery surface temperatures at different charging/discharging rates and thermal boundary conditions. The proposed methodology is applied to cylindrical LIBs of various chemistries.