Experimental and numerical investigation of phase change material filled mini cavity cooling for thermal management of high capacity lithium ion pouch cell

Abstract

High capacity batteries are gaining attention for their ability to store more energy and simplify electric vehicle pack design by reducing the number of cells but generate significant heat at high charging/discharging rates. This experimental and numerical study proposes a novel aluminum plate cooling system with mini-cavities filled with different phase change materials to improve lithium-ion cell safety and reliability while minimizing weight and operational costs. A three-dimensional numerical model has been developed using ANSYS Fluent to validate the numerical model against experimental results. Three cooling techniques are investigated: natural air convection cooling, Phase Change Material (PCM) block cooling, and a Phase Change Material filled mini-cavity cooling plate, with their thermal performances compared. During experiments, the melting behavior of organic material PCMs (OM-37, OM-42, and OM-46) is observed for both PCM block cooling and PCM-filled mini-cavity cooling at high charging rates. In the PCM block cooling case, uneven melting occurs, whereas in the PCM mini-cavity cooling system, uniform heat conduction through the aluminum plate ensures even PCM melting. The PCM mini-cavity cooling system improved pouch cell performance by 8.15 %, 7.24 %, and 5.34 % with OM-37, OM-42, and OM-46 at 3C charging. The segmented PCM mini-cavity, using OM-37 and OM-42 distributed along thermal gradients, kept cell temperature below 52 °C and ensured sequential melting with superior thermal uniformity compared to bulk PCM blocks. Pouch cell cycle analysis shows that natural convection led to swelling, while PCM mini-cavity cooling maintained structural integrity and stable temperatures. Overall, PCM mini-cavity cooling enhances battery safety, performance, and thermal stability.