Lithiation-induced swelling of electrodes

Abstract

Understanding the correlation between the deformation field and the diffusion of lithium in electrode materials can provide the knowledge of the effects of materials constants on the deformation behavior of lithiated electrode materials. In this work, we study the lithiation-induced swelling and deformation of three different electrodes of plate-like, cylindrical-shell and spherical-shell shapes under the framework of linear elasticity. Linear relationships between the lithium concentration and hydrostatic stress are derived for all the three different electrodes. For the diffusion of lithium with negligible contribution of stress-limited diffusion to the diffusion of lithium in electrode materials, the lithium-induced swelling is proportional to the partial molal volume of lithium and the state of charge for the three different electrodes of plate-like, cylindrical- and spherical shapes. The increase rate of the normalized surface displacement (the swelling) is the largest at the onset of lithiation and decreases gradually to a plateau with the increase of the lithiation time. Both the constraint and geometrical shape of an electrode play important roles in controlling the swelling and stress evolution in the electrode.