Design of Stable Hollow Particles for Silicon Anodes

Silicon electrodes hold a promise of increasing the capacity of lithium-ion batteries ten-fold. Yet, their commercial deployment is hampered by large volume changes of silicon particles in response to lithium insertion and extraction. Optimal design of porous silicon structures, aimed at ameliorating this drawback, requires experimentation guided by mathematical models of the chemomechanical behavior of silicon-anode particles and their agglomerations. We present such a model that describes the temporal evolution of a hollow or solid particle’s volume and concomitant stresses, for both galvanostatic and potentiostatic operating conditions. This model is used to optimize design parameters─particle size, particle thickness, and charging profiles─for energy density, while maintaining stable elastic operation. It accurately predicts the experimentally observed value of the partial molar volume of lithium in silicon. Our model also furnishes fundamental insights into chemomechanical interactions in multiparticle electrode systems, which are crucial for advancement of the silicon-electrode technology.