Design of Stable Hollow Particles for Silicon Anodes

Silicon\nelectrodes hold a promise of increasing the capacity of\nlithium-ion batteries ten-fold. Yet, their commercial deployment is\nhampered by large volume changes of silicon particles in response\nto lithium insertion and extraction. Optimal design of porous silicon\nstructures, aimed at ameliorating this drawback, requires experimentation\nguided by mathematical models of the chemomechanical behavior of silicon-anode\nparticles and their agglomerations. We present such a model that describes\nthe temporal evolution of a hollow or solid particle’s volume\nand concomitant stresses, for both galvanostatic and potentiostatic\noperating conditions. This model is used to optimize design parametersparticle\nsize, particle thickness, and charging profilesfor energy\ndensity, while maintaining stable elastic operation. It accurately\npredicts the experimentally observed value of the partial molar volume\nof lithium in silicon. Our model also furnishes fundamental insights\ninto chemomechanical interactions in multiparticle electrode systems,\nwhich are crucial for advancement of the silicon-electrode technology.