Towards a Mechanistic Model of Solid-Electrolyte Interphase Formation and Evolution in Lithium-ion Batteries (original) (raw)
Related papers
The formation of passivation films by interfacial reactions, though critical for applications ranging from advanced alloys to electrochemical energy storage, is often poorly understood. In this work, we explore the formation of an exemplar passivation film, the solid−electrolyte interphase (SEI), which is responsible for stabilizing lithium-ion batteries. Using stochastic simulations based on quantum chemical calculations and data-driven chemical reaction networks, we directly model competition between SEI products at a mechanistic level for the first time. Our results recover the Peled-like separation of the SEI into inorganic and organic domains resulting from rich reactive competition without fitting parameters to experimental inputs. By conducting accelerated simulations at elevated temperature, we track SEI evolution, confirming the postulated reduction of lithium ethylene monocarbonate to dilithium ethylene monocarbonate and H 2. These findings furnish fundamental insights into the dynamics of SEI formation and illustrate a path forward toward a predictive understanding of electrochemical passivation.
Reactive molecular dynamics simulations of Lithium-ion battery electrolyte degradation
2024
The development of reliable computational methods for novel battery materials has become essential due to the recently intensified research efforts on more sustainable energy storage materials. Here, we use a recently developed framework allowing to consistently incorporate quantum-mechanical activation barriers to classical molecular dynamics simulations to study the reductive solvent decomposition and formation of the solid electrolyte interphase for a graphite/carbonate electrolyte interface. We focus on deriving condensed-phase effective rates based on the elementary gas-phase reduction and decomposition energy barriers. After a short initial transient limited by the elementary barriers, we observe that the effective rate shows a transition to a kinetically slow regime influenced by the changing coordination environment and the 1
Physical chemistry chemical physics : PCCP, 2010
The decomposition of ethylene carbonate (EC) during the initial growth of solid-electrolyte interphase (SEI) films at the solvent-graphitic anode interface is critical to lithium ion battery operations. Ab initio molecular dynamics simulations of explicit liquid EC/graphite interfaces are conducted to study these electrochemical reactions. We show that carbon edge terminations are crucial at this stage, and that achievable experimental conditions can lead to surprisingly fast EC breakdown mechanisms, yielding decomposition products seen in experiments but not previously predicted.
Journal of Power Sources, 2011
We have studied the formation and growth of solid-electrolyte interphase (SEI) for the case of ethylene carbonate (EC), dimethyl carbonate (DMC) and mixtures of these electrolytes using molecular dynamics simulations. We have considered SEI growth on both Li metal surfaces and using a simulation framework that allows us to vary the Li surface density on the anode surface. Using our simulations we have obtained the detailed structure and distribution of different constituents in the SEI as a function of the distance from the anode surfaces. We find that SEI films formed in the presence of EC are rich in Li 2 CO 3 and Li 2 O, while LiOCH 3 is the primary constituent of DMC films. We find that dilithium ethylene dicarbonate, LiEDC, is formed in the presence of EC at low Li surface densities, but it quickly decomposes to inorganic salts during subsequent growth in Li rich environments. The surface films formed in our simulations have a multilayer structure with regions rich in inorganic and organic salts located near the anode surface and the electrolyte interface, respectively, in agreement with depth profiling experiments. Our computed formation potentials 1.0 V vs. Li/Li + is also in excellent accord with experimental measurements. We have also calculated the elastic stiffness of the SEI films; we find that they are significantly stiffer than Li metal, but are somewhat more compliant compared to the graphite anode.
The transition from lithium-based energy storage to post lithium systems plays a crucial part in achieving an environmentally sustainable energy infrastructure. Prime candidates for the replacement of lithium are sodium and potassium batteries. Despite being critical to battery performance, the solid electrolyte interphase (SEI) formation process for Na and K batteries remains insufficiently understood, especially compared to the well-established lithium systems. Using ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT) calculations, we study the first steps of SEI formation upon the decomposition of typical solvent molecules on lithium, sodium and potassium metal anodes. We find that two dominant products form during the early SEI formation of cyclical carbonates on alkali metal anodes, carbon monoxide and alkali-carbonate. The carbonate-producing reaction is thermodynamically favorable for all tested metals, however, Na and K exhibit a much str...
Journal of Electrochemical Energy Conversion and Storage, 2016
Understanding interfacial phenomena such as ion and electron transport at dynamic interfaces is crucial for revolutionizing the development of materials and devices for energy-related applications. Moreover, advances in this field would enhance the progress of related electrochemical interfacial problems in biology, medicine, electronics, and photonics, among others. Although significant progress is taking place through in situ experimentation, modeling has emerged as the ideal complement to investigate details at the electronic and atomistic levels, which are more difficult or impossible to be captured with current experimental techniques. Among the most important interfacial phenomena, side reactions occurring at the surface of the negative electrodes of Li-ion batteries, due to the electrochemical instability of the electrolyte, result in the formation of a solid-electrolyte interphase layer (SEI). In this work, we briefly review the main mechanisms associated with SEI reduction ...
Statistical Physics-Based Model of Solid Electrolyte Interphase Growth in Lithium Ion Batteries
The article presents a statistical physics-based model for the growth of the solid electrolyte interphase (SEI) in the negative electrode of lithium ion batteries. During battery operation, the SEI thickness grows by the reaction between lithium ions, electrons and solvent species on the surface of active particles at the negative electrode. The growth of the SEI layer causes a loss of lithium ions that induces capacity fade. In addition, it increases the ion transport resistance and decreases the total porosity. Our model employs a population balance formalism based on the Fokker-Planck Equation to describe the propagation of the particle density distribution function in the electrode. Structure-transforming processes at the level of individual particles are accounted for by using a set of kinetic and transport equations. These processes alter the particle density distribution function, and cause changes in battery performance. A parametric study of the model singles out the first moment of the initial SEI thickness distribution as the determining factor in predicting the capacity fade. The model-based treatment of experimental data allows analyzing processes that control SEI growth and extracting their controlling parameters. Lithium ion batteries (LIBs) are highly touted energy storage devices for portable electronics and electric vehicles. 1 The LIB system consists of a negative electrode, a positive electrode, a separator, an electrolyte, and two current collectors. The most commonly used elec-trolytes are comprised of lithium salts, such as LiPF 6 in a solution of ethylene carbonate (EC) and dimethyl carbonate (DMC). 1 The electrodes consist of randomly distributed and interconnected particles of active material, which store and release the lithium ions. Aging and degradation of LIBs have become major concerns for the operation of electric vehicles (EVs), which must fulfill exacting requirements in terms of durability, cyclability and overall lifetime. 2 Battery aging is linked to the (electro-)chemical and mechanical degradation of the electrodes and the electrolyte. 2 Three main degradation mechanisms prevail at the particle level during the cycling of LIBs: (1) growth of the solid electrolyte interphase (SEI) at the negative electrode, 2,3 (2) formation of cracks in the SEI layer at the negative electrode, 4 and (3) dissolution and isolation of nanocrystalline particles at the positive electrode. 5 These processes lead to capacity fade and power loss. At the beginning of the battery life, particularly during the first cycle, the electrolyte undergoes reduction at the electrode/electrolyte interface, because the negative electrode operates at potentials that are outside of the electrochemical stability window of electrolyte components. This reduction is accompanied by the irreversible consumption of lithium ions. 6 This process forms a passivating surface layer known as the solid electrolyte interphase. The SEI layer grows further during charging, thereby reducing the amount of active lithium ions. Moreover , this layer penetrates into the electrode pores, reducing the overall porosity and decreasing ion access to the active surface area of the electrode. 2 Understanding the mechanism of SEI thickness growth and the resulting composition of the layer is a vital topic of LIB research, because of its great practical significance and the intricate interplay of underlying processes. 2,6–14 The growth of the SEI involves a complex reaction network 15,16 that is sensitive to operating conditions as well as the battery cycling protocol. A mechanistic understanding of the processes involved in SEI formation and growth is vital for designing LIB systems with high performance and long cycle life. The topic therefore garners significant interest in the experimental and theoretical research community. Recent efforts in modeling of the electrochemical processes during cycling of LIBs include particle level models 17,18 and porous electrode theory. 16 In 1976, Bennion developed the first model of the SEI for lithium metal electrodes. 19 Peled further derived a parabolic growth law for the SEI considering the electron transfer as the rate-determining step in the growth of the SEI layer. 20 Ploehn et al. developed a model for SEI growth, in which the diffusion of solvent through the SEI is the rate-determining step. 21 Interestingly , this assumption also leads to a parabolic growth law. Newman et al. developed a model to predict the SEI growth based on porous electrode theory, including the detailed chemistry of SEI formation. 16 This model was the first attempt to link chemical reactions leading to SEI formation to irreversible capacity loss. However, it comprises a large number of model parameters. Xie et al. expanded Newman's model to incorporate thermal effects. 22 They found the battery skin temperature to significantly affect the growth of the SEI. Several subsequent works are based on Newman's model. Their common feature is that they couple a one dimensional model of charge and mass transport through the electrode to a one dimensional model of spherical diffusion inside active particles, resulting in a pseudo two-dimensional porous electrode (P2D) model. 23–26 Under low to moderate working conditions, the P2D model can be reduced to a single particle (SP) model. 27,28 In this approach, the electrode is represented by identical spherical particles, whose accumulated surface area is equivalent to the total active area of the solid phase in the porous electrode. This model assumes that the mass and charge transport resistances in solution can be neglected. Moreover, the faradaic current across the porous electrode exhibits a linear profile , which is valid in the limit of small applied currents in thin and highly conductive electrodes. 18 The modeling work presented in this article strives to establish relations among structural properties and electrochemical performance of the battery in order to rationalize the influence of SEI growth upon them. The central component of the statistical physics-based modeling framework is the Fokker-Planck Equation (FPE). The porous battery electrode is treated as a statistical distribution of interconnected particles. The FPE governs the temporal evolution of this distribution. The developed formalism allows leading causes of structural degradation , driven by (electro-)chemical and mechanical stressors, to be incorporated. Capacity and power fade as well as the battery cycle life can be analyzed in dependence of the initial structure, the external conditions and the cycling protocol applied, to predict the propagation of the particle density distribution function due to SEI growth. Eikerling and coworkers introduced a statistical modeling framework to study the degradation of platinum nanoparticles in the) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.169.25.245 Downloaded on 2017-12-10 to IP
Materials for Lithium Ion Batteries: Challenges for Numerical Simulations
Zeitschrift für Physikalische Chemie, 2012
ABSTRACT We present an overview of numerical challenges in simulating electronic and transport properties of battery assemblies. Li diffusion paths within inorganic materials (olivine phosphates) are investigated using a dedicated accelerated molecular dynamics approach. The need of many-body electronic structure calculations is illustrated for the evaluation of intercalation potentials (LDA/GGA+U) and of transport properties (LDA+DMFT). Steps towards the improvement of silicon based anodic materials are shown. All in all, the framework of an ab initio simulation platform for materials for power storage is sketched.
Microscopy and Microanalysis, 2014
Complex, electrochemically driven transport processes form the basis of electrochemical energy storage devices. The direct imaging of electrochemical processes at high spatial resolution and within their native liquid electrolyte would significantly enhance our understanding of device functionality, but has remained elusive. In this work we use a recently developed liquid cell for in situ electrochemical transmission electron microscopy to obtain insight into the electrolyte decomposition mechanisms and kinetics in lithium-ion (Li-ion) batteries by characterizing the dynamics of solid electrolyte interphase (SEI) formation and evolution. Here we are able to visualize the detailed structure of the SEI that forms locally at the electrode/electrolyte interface during lithium intercalation into natural graphite from an organic Li-ion battery electrolyte. We quantify the SEI growth kinetics and observe the dynamic self-healing nature of the SEI with changes in cell potential.
Progress in Energy, 2021
Since 1994, Kinetic Monte Carlo (kMC) has been applied to the study of Li-ion batteries and has demonstrated to be a remarkable simulation tool to properly describe the physicochemical processes involved, on the atomistic scale and over long time scales. With the growth of computing power and the widespread use of lithium-based storage systems, more contributions from theoretical studies have been requested. This has led to a remarkable growth of theoretical publications on Li-ion batteries; kMC has been one of the preferred techniques to study these systems. Despite the advantages it presents, kMC has not yet been fully exploited in the field of lithium-ion batteries and its impact in this field is increasing exponentially. In this review, we summarize the most important applications of kMC to the study of lithium-ion batteries and then comment on the state-of-the-art and prospects for the future of this technique, in the context of multi-scale modeling. We also briefly discuss the prospects for applying kMC to post lithium-ion chemistries such as lithium-sulfur and lithium-air.