Galvanic Corrosion and Electric Field in Lithium Anode Passivation Films: Effects on Self-Discharge

Abstract

Battery interfaces help govern rate capability, safety/stability, cycle life, and self-discharge, but significant gaps remain in our understanding at atomic length scales that can be exploited to improve interfacial properties. In particular, Li partially plated on copper current collectors, relevant to the anodeless, lithium metal cell which is a holy grail of high density energy battery research, has recently been reported to undergo galvanic corrosion and exhibit short shelf lives. We apply large scale Density Functional Theory (DFT) calculations and X-ray photoelectron spectroscopy to examine the reaction between the electrolyte and Li|Cu junctions coated with thin, uniform electrolyte interphase (SEI) passivating films at two applied voltages. These novel DFT galvanic corrosion simulations show that electrolyte degradation preferentially occurs on Li-plated regions and should lead to thicker SEI films. Our simulations reveal similarities but also fundamental differences between traditional metal localized pitting and Li-corrosion mechanisms. Furthermore, using the recently proposed, highly reactive lithium hydride (LiH) component SEI as example, we distinguish between electrochemical and chemical degradation pathways which are partially responsible for self-discharge, with the chemical pathway found to exhibit slow kinetics. We also predict that electric fields should in general exist across natural SEI components like LiH, and across artificial SEI films like LiI and LiAlO(2) often applied to improve battery cycling. Underlying and unifying these predictions is a framework of DFT voltage/overpotential definitions which we have derived from electrochemistry disciplines like structural metal corrosion studies; our analysis can only be made using the correct electronic voltage definitions.

arXiv comment41 pages. 8 figures

References in corpus (10)

• Quantifying Inactive Lithium in Lithium Metal Batteries
• Using atomic layer deposition to hinder solvent decomposition in lithium ion batteries: first principles modeling and experimental studies
• Stability of Solid Electrolyte Interphase Components on Lithium Metal and Reactive Anode Material Surfaces
• First-principles prediction of potentials and space-charge layers in all-solid-state batteries
• Dielectric properties of nano-confined water: a canonical thermopotentiostat approach
• DFT Modelling of Explicit Solid-Solid Interfaces in Batteries: Methods and Challenges
• Spatial Heterogeneities and Onset of Passivation Breakdown at Lithium Anode Interfaces
• Kinetics-Controlled Degradation Reactions at Crystalline LiPON/Li(x)CoO(2) and Crystalline LiPON/Li-metal Interfaces
• First Principles, Explicit Interface Studies of Oxygen Vacancy and Chloride in Alumina Films for Corrosion Applications
• Quantum-continuum calculation of the surface states and electrical response of silicon in solution

Cited by in corpus (1)

• First Principles Determination of the Potential-of-Zero-Charge in an Alumina-coated Aluminum/Water Interface Model for Corrosion Applications