Measurement of two-dimensional heat generation rate of pouch type lithium-ion battery using a multifunctional calorimeter

ABSTR A C T Accurate characterization of the heat generation rate (HGR) of lithium-ion batteries is critical for driving towards a cost-effective and efficient design of a thermal management system for various applications. Because of the increases in battery cell dimensions, as well as more aggressive operating conditions, heat generation seen at the cell level is becoming increasingly unevenly distributed. Proper design of the heat management system requires measurement of heat generation distribution at the cell level as a function of operating conditions, such as charging and discharging profiles, states-of-charge (SOC), temperature, and state-of-health (SOH). Currently, few commercial calorimeters are available for measurement of heat generation distributions under dynamic and varying operating conditions at reasonable price. In this paper, a new calorimeter is developed that allows for measurement of HGR in two-dimensions for a pouch format lithium-ion battery cell in real time, which consists of two thermoelectric assemblies (TEAs) with heat flux sensors to measure the HGR and temperature sensors to regulate the temperature. Distributed HGR of a large format pouch cell for automotive applications are measured as a function of different charging and discharging rates and SOCs as well as the variation of heat generation distribution during cell aging.