Mathematical model for silicon electrode – Part II. Simulations on different electrode nanostructures

Abstract The second part of the manuscript presents a one-dimensional axisymmetric plane strain model to study lithium insertion induced stresses in different types of silicon nanostructures, – nanowire (Si NW), nanotube (Si NT) and core/shell (Si C/S) nanostructures. The 1-d plane strain model is the dimensionally reduced form of the 2-d model presented in part I. Simulation results from the 1-d plane strain model is compared to the results from the 2-d model for the Si NW. Each of these structures poses a different type of boundary conditions and the stress evolution due to diffusion in each of the cases are discussed. Simulation results indicate that Si NT structures develop lower tensile stresses compared to Si NW structures under similar current densities. Case studies on Si NT for different values of inner to outer radii ratio are also presented. Furthermore, simulations reveal that the Si C/S structures develop much higher stresses (closer to the core/shell interface) compared to Si NW or Si NT, owing to the different expansion factors of the core and shell material.