The fracture of Si particles due to internal stresses formed during the intercalation of lithium ions was described by means of a thermal analogy model and brittle fracture damage parameter. The stresses were calculated following the diffusion equation and equations of elasticity with an appropriate volumetric expansion term. The results were compared with the acoustic emission data from the experiments on electrochemical cycling of Li ion half-cells with silicon electrodes. A good correlation between experiment and prediction was observed. The results of computations with different particle sizes show the existence of a critical size below which fracture during the lithiation is not expected to occur. Such a critical size appears to be within micrometer scale.