Thermal management of large format prismatic lithium ion batteries is challenging due to significant heat generation rates, long thermal ‘distances’ from the core to the surfaces and subsequent thermal gradients across the cell. The cell cooling coefficient (CCC) has been previously introduced to quantify how easy or hard it is to thermally manage a cell. Here we introduce its application to prismatic cells with a 90 Ah prismatic lithium iron phosphate cell with aluminium alloy casing. Further, a parameterised and discretised three-dimensional electro-thermal equivalent circuit model is developed in a commercially available software environment. The model is thermally and electrically validated experimentally against data including drive cycle noisy load and constant current CCC square wave load, with particular attention paid to the thermal boundary conditions. A quantitative study of the trade-off between cell energy density and surface CCC, and into casing material selection has been conducted here. The CCC enables comparison between cells, and the model enables a cell manufacturer to optimise the cell design and a systems developer to optimise the pack design. We recommend this is operated together holistically. This paper offers a cost-effective, time-efficient, convenient and quantitative way to achieve better and safer battery designs for multiple applications.
Bibliographical noteFunding Information:
The authors would like to acknowledge the funding support received from Envision-AESC, Ltd. for Xiao Hua and funding from the Faraday Institution (faraday.ac.uk; )EP/S003053/1, grant number FIRG003 for Gregory Offer. The work was also supported by Alessandro Picarelli from Claytex UK, Danny Montgomery from Thermal Hazard Technology UK and Yan Zhao from Imperial College London.
© 2020 Elsevier B.V.
- 3D discretised electro-thermal equivalent-circuit model
- Cell design
- Electric vehicle
- Lithium iron phosphate
- Lithium-ion battery
- Prismatic surface cell cooling coefficient