Multiphysics analysis of electrochemical and electromagnetic system addressing lithium-ion battery and permanent magnet motor

Lithium-ion batteries are the leading energy storage technology in the electronic-driven society. With the need for portable, long-life electronics the demand for lithium batteries has escalated over the decade. Lithium-ion batteries show remarkable electrochemical characteristics, including but not limited to, long cycle-life, high cut-off voltages and high energy-density. However, lithium-ion cells are problematic to design due to their inherent thermal and/or mechanical instability. The objective of the current research framework is to establish the criteria causing thermo-mechanical failure of the battery systems, material properties effecting the performance, and model cycle-life degradation due to electrolyte loss by solid electrolyte interface (SEI) formation. An extension of this thermo-mechanical analysis was performed on electromagnetic system. A FEM was performed for a 20W BLDC motor to predict the electromagnetic and thermo-mechanical performance under steady state operating conditions. In our present research, we have studied the mechanical and thermal aspect of lithium battery electrodes. The first and second project encapsulated the material selection aspect for thermo-mechanically stable lithium battery electrodes. The objective of these projects was to develop a set of material indices (five for mechanical and five for thermal) which compare the performance of electrode materials based on heat generation, diffusion and mechanical strength and toughness. A mathematical model was formulated to determine particle deformation and stress fields based upon an elastic-perfectly plastic constitutive response. Mechanical deformation was computed by combining the stress equilibrium equations with the electrochemical diffusion of lithium ions into the electrode particle. The result provided a time developing stress field which shifts from purely elastic to partially plastic deformation as the lithium-ion diffuses into the particle. For the mechanical integrity, the materials were tested for strength, and toughness under elastic and plastic deformation. The model was used to derive