Diffusion-induced stresses of spherical core-shell electrodes in lithium-ion batteries: The effects of the shell and surface/interface stress

Core-shell electrode nanoparticles improve the electrochemical performance of lithium-ion batteries, resulting from intrinsic electric conductivity and excellent tolerance to mechanical stress of the shell. To study diffusion-induced stresses of core-shell nanostructures, we develop a model for spherical electrodes covered with shells including the effects of surface/interface stress, and further take carbon shell as an example. The results show that carbon shell greatly buffers the volume expansion and alleviates tensile stresses of inner active core, and diffusion-induced stresses strongly depend on the thickness and Young'smodulus of carbon layer, which should be tuned on the basis of material strengths and electrochemical capacity. In addition, residual surface/interface tension significantly reduces diffusion-induced stresses through the electrode materials, which may become a resistance to brittle fracture.