Extended Volume Bomb Calorimetry

Calorimetry is a critical technique for studying thermal runaway in lithium-ion cells by precisely measuring the heat generation, temperature rise, and energy release during failure events. Using specialized calorimeters, researchers can subject cells to controlled conditions to assess their thermal stability and failure mechanisms. Understanding the thermal behavior of lithium-ion cells through calorimetry is essential for enhancing battery safety in high-risk applications, including aerospace, defense, and electric vehicles.

Adiabatic bomb calorimetry is a technique used to measure the total heat energy released during the combustion or decomposition of a material under controlled conditions. In this method, a sample is placed inside a sealed, high-pressure vessel (the bomb), which is then filled with inert gas and surrounded by a thermally controlled environment designed to minimize heat loss. When the sample is ignited, the heat generated raises the temperature of the surrounding medium, allowing precise calculation of the material’s energy content. This technique is widely used in battery safety research to evaluate the thermal runaway characteristics of lithium-ion cells by quantifying the total energy released during failure events, aiding in the development of safer battery designs and thermal management strategies.

Adiabatic calorimetry using the Accelerating Rate Calorimeter (ARC) heat-wait-seek (HWS) methodology is a powerful technique for characterizing thermal runaway in lithium-ion cells. In this process, the battery cell is placed in an adiabatic environment where heat loss is minimized, ensuring that any heat generated remains within the system. The HWS protocol involves gradually heating the cell in small increments (“heat”), pausing to allow thermal equilibration (“wait”), and monitoring for any self-heating behavior (“seek”). If self-heating exceeds a predefined threshold, the ARC automatically follows the reaction as it escalates toward thermal runaway, capturing critical data such as onset temperature, heat generation rates, and total energy release. This approach enables researchers to assess material decomposition thresholds and failure mechanisms at the cell level.