Lithium ion batteries experience diffusion-induced stresses during charge and discharge processes which can cause electrode failure in the form of nano particle technology handbook pdf. Previous diffusion-induced stress models and simulations are mainly based on simple active material particle structures, such as spheres and ellipsoids. However, the simple structure model cannot reveal the stress development in a real complex lithium ion battery electrode. In this paper, we studied the diffusion-induced stresses numerically based on a realistic morphology of reconstructed particles during the lithium ion intercalation process.
Diffusion-induced stresses were simulated at different C rates under galvonostatic conditions and compared with spherical particles. The simulation results show that the intercalation stresses of particles depend on their geometric characteristics. The highest von Mises stress and Tresca stress in a real particle are several times higher than the stresses in a spherical particle with the same volume. We studied diffusion-induced stresses based on realistic 3D microstructures. Stresses depend on geometric characteristics of electrode particle.
Stresses in a real particle are much higher than those in a spherical particle. Check if you have access through your login credentials or your institution. Emulsions encompass a vast number of everyday materials and products including foodstuffs, personal care items, and pharmaceuticals. However, as emulsions are inherently thermodynamically unstable, understanding the theoretical factors influencing emulsion stability is critical to the emulsion formulator. Brownian flocculation, creaming, sedimentation flocculation and disproportionation, shown schematically in Figure 1.
The processes of creaming, flocculation and coalescence are well demonstrated by taking an emulsion of limited stability and centrifuging it at low speeds or various lengths of time. Then, as larger droplets rise and concentrate, they begin to appear at the top. Finally, the drops coalesce to form a separate layer of oil on top. Creaming is the principal process by which the disperse phase separates from an emulsion and is typically the precursor to coalescence. The Stokes’ equation shows that creaming is inhibited by a small droplet radius, a highly viscous continuous phase and a low density difference between the oil and water phases. 5 cm per day which is not insubstantial.