Using a fully-coupled diffusion-elasticity model with Butler-Volmer surface kinetics, we simulate the insertion of lithium into spherical silicon particles. Simulations predict the evolution of concentration, displacements, and stresses in the particles during the first insertion of Li. The particle response depends strongly on the reaction kinetics and the resulting stresses can be above the tensile failure stress of silicon depending on the particle size and discharge rate. (C) 2010 American Institute of Physics. [doi:10.1063/1.3458707]