(55bd) A New Thermal Runaway Calorimeter for Battery Safety Evaluation

Lithium-ion batteries (LIBs) have raised increasing interest due to high energy density and efficient energy storage. However, safety is a major concern, and a large number of LIBs have been recalled due to explosion and fire accidents. Consequently, increasing attention is being paid to LIB safety issues and a large number of safety strategies are being developed. Cells are equipped with safety features such as separator shut down to stop the flow of current and opening of the vent to help prevent the cell from bursting and/or catching fire in addition to others.

Thermal modelers of battery and battery packs are looking for the thermal properties of batteries in the event of thermal runaway which includes temperature rise rates, peak cell temperature and total energy release. Accelerating rate calorimeter (ARC®) is the most used calorimeter for battery safety evaluation including thermal runaway properties. Often test results underestimate these properties especially in the event when cell heating rates are high and/or end temperature of the cell reached higher than the instrument’s capabilities.

Belmont Scientific, Inc. has developed a thermal runaway calorimeter (TRC) which measures temperature rise rates of the cell as well as total heat release in the event of thermal runaway close to reality. Test also provides the information regarding voltage drop temperatures and vent opening temperature. Autor has studies a typical 21700 cylindrical cell using ARC and TRC and shown in Figure 1 below. The peak cell temperature recorded was 1095ËšC with total heat release of 103kJ. Cell voltage drop at 137ËšC and vent open temperature was 145ËšC. TRC also have capability to measure pressure and pressure rise rate and peak pressure generated during thermal runaway can be estimated. Thermal runaway gases can be collected for gas analysis.