Multiphysics Model of the Thermal Behavior of a Lithium Metal Solid State Battery

Abstract

While it is often stated that solid state batteries are safer than Li-ion batteries with liquid electrolytes, especially for the case of solid state batteries with a lithium metal anode (and hence a higher specific energy than a conventional Li-ion cell), the thermal behavior of the cell upon external heating, internal shorting, and other forms of abuse or failure requires careful analysis. We address this question by building a thermal model of a large-format (e.g., 60 Ah class) cell, making use of chemical reactivity data obtained from a complete solid state battery within a differential scanning calorimetry (DSC) pan. We use our model to simulate a thermal ramp test and short-circuit to study the thermal behavior of an LCO|LLZO|Li metal prismatic cell. Our model allows us to assess the temperature at which self-heating and thermal runaway occur, in addition to the amount of heat that is generated and the rate of heat generation. Our presentation will cover our model formulation, the experimental basis for the self-heating reactions, and results including temperature, reactant consumption, and heat evolution throughout the duration of each thermal stress test. We may also discuss our experimental work to expand on available DSC data for all-solid-state cells and present thermogravimetric analysis as well as DSC data for different solid-state battery chemistries.