Interfacial Atomistic Mechanisms of Lithium Metal Stripping and Plating in Solid‐State Batteries

Abstract

All‐solid‐state batteries based on a Li metal anode represent a promising next‐generation energy storage system, but are currently limited by low current density and short cycle life. Further research to improve the Li metal anode is impeded by the lack of understanding in its failure mechanisms at lithium–solid interfaces, in particular, the fundamental atomistic processes responsible for interface failure. Here, using large‐scale molecular dynamics simulations, the first atomistic modeling study of lithium stripping and plating on a solid electrolyte is performed by explicitly considering key fundamental atomistic processes and interface atomistic structures. In the simulations, the interface failure initiated with the formation of nano‐sized pores, and how interface structures, lithium diffusion, adhesion energy, and applied pressure affect interface failure during Li cycling are observed. By systematically varying the parameters of solid‐state lithium cells in the simulations, the parameter space of applied pressures and interfacial adhesion energies that inhibit interface failure during cycling are mapped to guide selection of solid‐state cells. This study establishes the atomistic modeling for Li stripping and plating, and predicts optimal solid interfaces and new strategies for the future research and development of solid‐state Li‐metal batteries.

Suppressing void formation in all-solid-state batteries: the role of interfacial adhesion on alkali metal vacancy transport

“…The simple bond breaking model developed in this work provides a mechanistic understanding of previous experimental and computational results of vacancy diffusion and allows for the rational design of new materials to suppress void growth. In the molecular dynamics study by Yang et al, 47 it was demonstrated that a work of adhesion of W ad 0.7 J/m 2 was > required to suppress voids at a model incoherent BCC Li (100)/SSE interface, with the application of a pressure on the order of 10-20 MPa. Without the application of pressure, a W ad 1.8 J/m 2 was required.…”

“…In the current study, only sharp alkali metal/SSE interfaces were considered from DFT calculations, whereas in real systems, significant reconstruction or amorphization of the alkali metal at the interface may occur. 47,70,77 The simple bond breaking model is still likely to be applicable for these systems, as was the case for incoherent interfaces, although care must be taken to accurately model the distribution of possible and values in systems with lower crystallinity. Due to the large cost of DFT calculations of explicit interfaces, only single, isolated alkali metal vacancies were considered in this study to understanding the fundamental relationship between interfacial adhesion and vacancy segregation.…”

“…46 In another study by Yang et al, large-scale molecular dynamics calculations were used to show how both the work of adhesion and the pressure affect void formation at a model Li metal/SSE interface. 47 It was demonstrated that a work of adhesion W ad 0.7 J/m 2 was > required to suppress voids at the BCC Li (100)/SSE interface with the application of a moderate pressure (10-20 MPa). 47 A fundamental difference was also observed in this study between coherent and incoherent Li metal/SSE interfaces, in which lower Li vacancy diffusion into the Li bulk was observed in the latter case.…”

“…47 It was demonstrated that a work of adhesion W ad 0.7 J/m 2 was > required to suppress voids at the BCC Li (100)/SSE interface with the application of a moderate pressure (10-20 MPa). 47 A fundamental difference was also observed in this study between coherent and incoherent Li metal/SSE interfaces, in which lower Li vacancy diffusion into the Li bulk was observed in the latter case.…”

Confronting the Challenges in Lithium Anodes for Lithium Metal Batteries

“…Calculation and simulation, such as, molecular dynamic simulation and phase field model, are used to propose new directions for the improvement of host materials, electrolyte formulations, etc. [25,26] In this review, advanced studies on lithium anode in lithium metal batteries are discussed. Strategies in this paper are mainly divided into two categories: a) Establish an external barrier.…”