Lithium ion batteries (LIBs) are used as a power source in a wide range of portable electronic applications. However, practical applications of LIBs are still hampered by severe capacity loss, with the dissolution of transition metals (TMs) from cathode materials being one of the major factors. TM dissolution also contributes to the formation of solid electrolyte interface (SEI) that deteriorates the performance of LIBs and limit their life cycle. Understanding the mechanisms and kinetics of TM dissolution at the atomic level is essential for developing rational strategies to inhibit cathode degradation. Here, by employing a series of density functional theory (DFT) calculations augmented by ab initio molecular dynamics (AIMD) simulations we explore the interactions between electrolyte species and the LiNi0.5Mn1.5O4 (LNMO) (001) cathode surface. We harness enhanced free-energy sampling techniques to simulate TM dissolution with explicit treatment of the organic electrolyte to examine the kinetics of TM dissolution. By considering various species present in the electrolyte, we contrast dissolution of Mn and Ni and analyze the contribution of different factors into dissolution barriers (nature of organic and inorganic species, surface protonation and oxygen vacancies). The obtained results also demonstrate that it is possible to correlate adsorption strength of electrolyte species with the dissolution kinetics.

Ab initio modeling of transition metals dissolution from LiNi0.5Mn1.5O4

2019 Fall National Meeting

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