Lithium insertion and removal in lithium ion battery electrodes can result in diffusion induced stresses (DISs) which may cause fracture and decrepitation of electrodes. Many lithium ion electrode materials undergo formation of two or more phases during lithium insertion or removal. In this work, we mathematically investigate the DISs in phase transforming electrodes using a core-shell structural model. We examine the concentration jumps at phase boundaries that result in stress discontinuities, which in turn can cause cracking. The influence of the mechanical properties of the two phases on stress evolution, stress discontinuity, and strain energy are clarified. The trends obtained with the model may be used to help tune electrode materials with appropriate interfacial and bulk properties so as to increase the durability of battery electrodes. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3565183]