Thermal-electrochemical model for passive thermal management of a spiral-wound lithium-ion battery

Safe and reliable operation of a Li-ion battery requires control and often management of the thermal envelope. In this context, a two-dimensional, transient mathematical model comprising conservation of charges, species, and energy together with electroneutrality, constitutive relations and relevant initial and boundary conditions for a spiral-wound cylindrical Li-ion battery is derived and solved numerically for passive thermal management with and without a phase change material (PCM) at various galvanostatic discharge rates. Two-way coupling of the electrochemical and thermal equations of change is attained through heat generation terms and temperature-dependent physical properties. Within this framework, the electrochemical and thermal behavior is discussed in terms of edge effects arising from the design of the spiral-wound structure and variations in heat generation in the functional layers. In addition, the cell performance with passive thermal management through a PCM is shown to lower the overall temperature of the cell at discharge rates around 5 C-rates, provided the PCM layer is thick enough to provide cooling during the entire discharge. The model can be employed for wide-ranging parameter studies as well as multi-objective optimization of not only design parameters pertaining to the spirals but also, for example, for design of the thickness of the PCM layer. (C) 2011 Elsevier B.V. All rights reserved.