Reducing Diffusion-Induced Stress of Bilayer Electrode System by Introducing Pre-Strain in Lithium-Ion Battery

Abstract

Lithium-ion battery (LIB), as energy storage devices, is widely used in portable electronic devices and have promising applications in electric vehicles. The volume change and large stress can lead to electrode pulverization and the resultant loss of electrical contact from the current collector, which is considered to be one of the main reasons for the capacity degradation of LIB. To reduce diffusion-induced stress of the electrode system during lithium-ion diffusion, a chemo-mechanical coupled theoretical model of bilayer electrode system of electrode layer bonded to the current collector is established. The theoretical results show that diffusion-induced stresses at the electrode–collector interface and maximum tensile stress at the top surface of the electrode layer are alleviated greatly by introducing pre-strain. The effects of pre-strain and lithium-ion concentration on chemo-mechanical coupled behavior of the bilayer electrode system are discussed. In particular, the lithium-ion concentration difference strongly depends on the diffusion thickness and time. The curvature when considering plastic deformation is smaller than that when not considering the plastic deformation. In addition, the effects of plastic deformation of the current collector and diffusion time on biaxial stress distribution are also discussed. The biaxial stress decreases with the increase of pre-strain and decrease of dimensionless time during galvanostatic charging. The biaxial stress when considering plastic deformation is smaller than that when not considering the plastic deformation. The results obtained from this investigation will provide a reference to reduce the diffusion-induced stress and improve the ion diffusion performance of LIB.