Abstract
The large volume change during lithium-ion insertion/extraction leads to huge stress and even failure of active materials. To well understand such a problem, the two-phase lithiation process of film and hollow core-shell electrodes is simulated by using a non-linear diffusion lithiation model. The dynamic evolution of lithium-ion concentration and diffusion-induced stress are obtained. Based on the dimensional analysis, a phase diagram is determined to demonstrate the relationship between critical failure, structure dimensions and mechanical properties. As a case study, the critical state of charge in Sn films are measured and compared with theoretical results.
Highlights
Because of the large storage capacity and high energy density, lithium-ion batteries (LIBs), one of the most promising secondary cells,[1,2,3] have been widely used in portable electronic devices
The large number of Li-ions inserting into high-capacity electrode materials may result in a huge volume change (400% for full lithiation of Si),[6] and a series of shortcomings: fracture or pulverization of active materials, breakage of a conduction path for electrons and lose of electrical contact, and destruction of solid electrolyte interphase formed by the reaction between active materials and electrolyte
A lot of theoretical models and experiments have been done on diffusion-induced stress and structural failure in high-capacity electrode materials, there is still lack of a good understanding on the detailed dynamic evolution of stress field induced by large volume deformation, and the effects of structural size and material properties on electrochemical performance
Summary
Because of the large storage capacity and high energy density, lithium-ion batteries (LIBs), one of the most promising secondary cells,[1,2,3] have been widely used in portable electronic devices. The large number of Li-ions inserting into high-capacity electrode materials may result in a huge volume change (400% for full lithiation of Si),[6] and a series of shortcomings: fracture or pulverization of active materials, breakage of a conduction path for electrons and lose of electrical contact, and destruction of solid electrolyte interphase formed by the reaction between active materials and electrolyte. They can rapidly fade electrochemical properties of active materials and result persistent decrease of their long-term coulombic efficiency.[11,12,13,14,15]. Diffusion equations of two-phase lithiation.—The transport of Li-ions in an electrode can be modeled as a concentration-driven bulk diffusion process, and the diffusion flux of Li-ions, J, can be represented as
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