Ionic Transport through the Solid Electrolyte Interphase in Lithium-Ion Batteries: A Review from First-Principles Perspectives

This review aims to give a collective analysis of ionic transport mechanisms through the solid electrolyte interphase (SEI) in lithium-ion batteries. In electrochemical cells, the SEI is the least understood and most important complex thin layer that forms on electrodes when they come in contact with electrolytes. Though the SEI is the key factor in any electrochemical cell, the complete picture of the SEI is still fuzzy because of its diverse and dynamic nature. To address the complexity of this interphase, the fabric of this review is arranged in such a way that each component of the SEI is separately analyzed by means of its chemical structure and the possible diffusion mechanism. Since most of the studies about ionic transport through the SEI are based on first-principles studies, a section of this review is devoted to discussing the theoretical concepts of ionic transport. Further, this review has audited other possible means of ionic transport occurring through grain boundaries including open channels. A brief overview of the electronic conductivity of SEI components is also included herewith.