Online temperature estimation for phase change composite - 18650 lithium ion cells based battery pack

This paper proposes the design of an online temperature estimation technique for a Li-ion battery pack that utilizes phase change composite (PCC™) for thermal management. The phase change composite allows heat absorption and distribution, enabling lightweight and compact packs with extended cycle-life and safety. A coupled electro-thermal model has been developed for the cylindrical 18650 Li-ion cells, from which the cell heat generation is calculated. The electrical equivalent circuit comprises three RC pairs, where their values are functions of temperature and state of charge. An analytical thermal model is developed for the battery pack, considering the phase change composite and cells, which allows online temperature estimation all over the battery pack.