(Digital Presentation) Modeling Thermal Behavior and Safety of Large Format All-Solid-State Lithium Metal Cells Under Thermal Ramp and Short Circuit Conditions

Abstract

We are submitting this abstract in the understanding that a virtual option is likely to be offered for the Spring, 2022 ECS meeting. We are only interested in the virtual option for this presentation. It has often been posited that solid-state batteries are inherently safer than liquid electrolyte Li-ion batteries because there is no flammable organic solvent present in the battery. However, thermal safety is a multi-faceted issue with other considerations such as onset temperature, maximum temperature, total heat generation, maximum heating rate, etc. These considerations need to be looked at in greater detail, including their dependence on the volumetric and gravimetric energy densities. Safety concerns become even more important as stable graphite anodes are replaced with potentially highly reactive and energetic lithium metal anode. In this presentation, we will report on our work using differential scanning calorimetry (DSC) heat flow data to construct a transient, 2D model of heat generation and temperature distribution in a large format cell with a LixCoO2 cathode, Li7La3Zr2O12 solid electrolyte, and lithium metal anode. We will present on the thermal runaway behavior of this cell chemistry during a thermal ramp test in an oven and due to the formation of an internal short circuit. Our analysis will focus on the total amount of heat generated, onset temperature for self heating, maximum temperature, and maximum heating rate. We also analyze how the battery state of charge affects these properties. Related work in our group focuses on collecting DSC data for Li metal solid state cells and may also be highlighted.