Modeling Nickel Oxide Particle Stress Behavior Induced by Lithiation Using a FEM Linear Elastic Approach

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Modeling the electrochemical behavior of Lithium Ion Batteries is a challenging task due to the high number of transient variables to consider (solid electrolyte interphase formation, reaction reversibility, electrolyte decomposition, electrode structural change, etc.). Nonetheless, a theoretical approach that can allow for the close simulation of battery performance, including real capacity, cycle life and stress tensor inside the material can provide important insights into the behavior of electrodes in operating systems. This work employs a linear elastic particle stress model to investigate the stress behavior of NiO spherical nanoparticles during lithiation and delithiation. The results show that the stress rising in the particles during charge/discharge cycles is closely related to the current rate applied to the cell and the average particle size. Moreover, a clear trend can be found correlating the stress developed in active material particles to the charge rate and to the depth of charge/discharge of the cells. Experimental data confirmed the model predictions, and a link between the internal stress of the active material, in cells run at 1C rate compared to those run at 5C, and cyclability was made.