bluuebunny/crossref_metadata_2025_split huggingface dataset:
(A04 Best Poster Award Winner) Formation Mechanism and Stability of Solid Electrolyte Interphases in Linear Carbonate-Based Electrolytes
Authors: Ebrahiminia Mahsa , Wang Cun , Bedrov Dmitry 
Published: December 2020

Broad application of lithium batteries, necessitates improvements in their safety, cycle life, durability and energy density. Clear understanding of the electrode/electrolyte interfaces is one of the important factors in designing batteries with enhanced performance. Linear organic solvents are extensively used in electrolytes of lithium batteries to reduce viscosity and melting temperature of cyclic carbonates. However, these organic compounds are not stable in contact with anode, leading to decomposition of the electrolyte and formation of Solid Electrolyte Interphase (SEI). Although SEI is proven to be one of the most important parts of batteries, its structural complexity, mechanism of formation, and properties are not completely understood yet. In this work, we consider mechanism of formation and stability of SEIs composed of redox products of linear carbonate solvents. So far, the main focus of research was on decomposition products of cyclic carbonates. In case of linear carbonates, the SEI stability consideration is limited to the systems being in DMC solvent and to the best of our knowledge, there are no theoretical investigations on linear carbonate-based SEIs formation mechanism and properties.
In this work, we study Lithium Methyl Carbonate (LMC), Lithium Ethyl Carbonate (LEC) and Lithium Propyl Carbonate (LPC), which are single-electron reduction products of carbonate solvents in contact with the electrode, in their corresponding solvents being Dilithium Methyl Carbonate (DMC), Dilithium Ethyl Carbonate (DEC) and Dilithium Propyl Carbonate (DPC), respectively (Figure 1). Our aim is to chemically, kinetically, and thermodynamically study the aggregation, formation and stability of SEI layer in these systems from experimental, Molecular Dynamics (MD) simulation and Density Functional Theory (DFT) calculation points of view. Our study indicates that in LMC/DMC mixture LMC molecules have strong tendency to self-assemble and have low barriers to undergo second-electron reduction to form stable Li2CO3. Stable SEI was also observed in LPC/DPC as well, which is believed to be a result of slow dynamics of larger molecules and therefore increased possibility of the second-electron reduction near electrode surface. In the LEC/DEC system, however, we did not observe a stable SEI formation due to low tendency of LEC molecules to self-assemble, low electronic affinity coupled with high energy barrier for possible second electron reduction reaction. Therefore, our work illustrates that the selection of the linear carbonate as a blending partner for cyclic carbonates, might have an important impact on the ability of electrolyte to form stable and compact SEI layer.

Figure 1
Potential Dependent Ion Arrangement Near the Electrode/Electrolyte Interface
Authors: Mars Julian Emanuel , Steinrück Hans-Georg , Cao Chuntian , Borodin Oleg , Toney Michael F 
Published: December 2020

The electric double layer (EDL) is the ion arrangement evolving at electrolyte interfaces. Despite its importance in many applications such as super-capacitors, lithium ion batteries (LIB), water purification, and stabilization of nanoparticles in solution, the structural motifs of the EDL are still under debate.
In LIB, the molecular scale ion arrangement near the interface or EDL controls solvation and hence mass/charge transfer across the interface. Additionally, the interfacial speciation governs the reductive and oxidative processes at the interface. Thus, it has a great impact on the stability of the electrolyte. Hence, the near-interface structure plays a vital role in the solid electrolyte interphase (SEI) formation which is still poorly understood. The SEI protects the electrolyte from further decomposition and its stability, low electrical conductance, and good Li-ion transport properties are crucial for the cycling ability and long-term stability of the cell. Therefore, an atomic level elucidation of the electrolyte/electrode interface and its rearrangement dynamics due to potential changes is of utmost importance for understanding the behaviors of LIBs, and will ultimately lead to the minimization of ion transport resistance and improved long-term stability.
We present an in-situ X-ray reflectivity (XR) study on the single crystalline boron-doped diamond – electrolyte interface. The metal-like electric conductivity and wide electrochemical window of the single crystalline boron-doped diamond allow us to apply a potential across the interface. We obtain structural information by modeling the potential dependent EDL to reproduce our experimental data. First proof-of-concept results on 1m CsCl(aq) show a clear trend of the XR profile on the applied potential of -1.2V – 1.2V vs AgCl. The length scale of π/qz = 4Å of the observed minima at qz = 0.75 Å−1 corresponds well to the expected length-scale of the inner-Helmholtz layer of the EDL. Our analysis suggests that the population of the inner-Helmholtz layer decreases with increasing potential.
Our efforts allow to challenge the current theoretical models and simulations and will ultimately help to understand the mechanisms involved in the SEI formation and lead to the minimization of ion transport resistance as well as to an improvement of the LIB cycling ability.

Figure 1
Electrolyte Conditions in Li-Ion Batteries in Presence of a Thermal Gradient
Authors: Guillamon Moreira Joaquin I. , Love Corey T. , Carter Rachel E. , Yang Xue , Verma Amit 
Published: December 2020

Safety is one of the big concerns to tackle for large-scale application of Li-ion batteries. With higher amounts of energy stored per unit volume and higher current densities flowing through the device, energy dissipation in the form of heat is becoming one of the main issues for proper battery operation. If temperature increases, secondary chemical reactions may be initiated. These reactions release more heat and undesired products, triggering an auto-catalytic feedback process to occur, which is commonly classified into thermal-runaway mechanisms. This can potentially lead to a complete degradation of the battery, and possible explosion or combustion of the battery components.
Several researchers have worked on developing models to predict thermal behavior under abuse conditions with potential thermal runaway outcomes on Li-ion batteries. Hatchard et al. (2001) proposed a model that emulates the SEI decomposition and regeneration reactions on a standard 18650 cylindrical cell. Lopez et al. (2015) extended the previous work and also included the reactions of cathode decomposition and electrolyte decomposition with potential combustion. Although macroscopic level energy balance helps to predict potential thermal behavior in a battery of multiple layers, the study of all the different transport mechanisms that happen inside a single layer battery is essential for a better understanding of the process taking place when temperature begins to rise. With the aim of improving heat dissipation inside a battery, the electrolyte is a key component to consider as it can potentially handle heat flux easier through convention within the solution. This work investigates spatially dependent electrolyte conditions in the presence of a thermal gradient in order to produce a thermal runaway model. The objective of the study is to model transport mechanisms that might lead to thermal degradation of the battery. Li- ions, electrons, momentum, and thermal flux are the main components of the analysis. Numerical simulation techniques are used for this purpose. A thorough comprehension of the transport processes taking place inside the battery contributes to avoiding damage induced due to thermal abuse conditions.
Controlling the Nucleation Morphology of Lithium Using ALD-Grown TiO2
Authors: Oyakhire Solomon , Huang William , Cui Yi , Bent Stacey F. 
Published: December 2020

Lithium (Li) metal batteries are desirable as rechargeable storage devices due to their high energy density; however, their practical implementation is hindered by the difficulty in controlling the Li metal plating microstructure. Artificial solid-electrolyte interphases (SEIs) have shown the potential to curtail the electrochemical instabilities of lithium, and atomic layer deposition (ALD) is commonly employed for the synthesis of thin-film artificial SEIs such as Al2O3 and alucone. However, these films quickly become delaminated as a result of their innate resistance to the cyclic shuttling of Li ions, resulting in marginal improvements in cell performance.
Herein, we detail the use of ALD-grown TiO2 as a nucleation layer, rather than as an artificial SEI. We show that by depositing TiO2 directly on the Cu current collector, we can control the deposition morphology of Li in the widely studied ether-based electrolyte - 1M LiTFSi in an equal volume mixture of 1,3 dioxolane and 1,2 dimethoxyethane, with 1 weight percent of lithium nitrate as an additive. By optimizing the thickness of TiO2, we reveal that lithium nucleates into large deposits atop the TiO2 film under significantly reduced overpotential, resulting in a reduction in contact surface area with the electrolyte and an increase in cell performance. We report substantial improvements in cycling efficiency with an average Coulombic efficiency of 96% after 150 cycles at a current density of 1 mA cm-2 in Li/Cu cells. In comparison to the pristine cells, voltage profiles for the champion TiO2-modified cell display negligible loss in charge capacity in the mid and late-stage electrochemical cycles, indicating an improvement in the reversibility of lithium stripping and plating. Using X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), we establish that lithium plates atop TiO2, rather than beneath it, suggesting that the presence of TiO2 supports the enhanced reversibility of Li stripping and plating. Also, we utilize coulometry and transmission electron microscopy (TEM) measurements to establish the effects of the TiO2 film. All performance and characterization data will be presented and discussed.
Combined Multi-Physics and Machine Learning Approach to Forecast SEI Decomposition in LIBs
Authors: De Angelis Paolo , Yurkiv Vitaliy , Asinari Pietro , Mashayek Farzad 
Published: December 2020

Over the last two decades, the tremendous efforts of researchers brought the Li-ion battery (LIB), based upon the intercalated graphite electrode, to its advanced level enabling their wide-spread application. Unfortunately, high demand led to many safety problems especially associated with thermal runaway. A very common reason of LIBs’ thermal runaway is the exothermic decomposition of solid electrolyte interface (SEI) leading to a battery’s rapid self-heating and in extreme scenarios to explosion. It is very challenging to suppress, control or sometimes even observe the thermal runaway due to the SEI formation/decomposition in realistic operation conditions. However, the evolution of thermal and electric parameters during LIBs operation may indicate the occurrence of thermal runaway, which will allow its early forecasting and corresponding suppression.
In order to predict the thermal runaway in LIBs, we use machine learning (ML) techniques, in particular, convolutional neural network (CNN) and deep neural network (DNN) to identify temperature pattern change leading to the thermal runaway. The ML methods are trained based upon the images obtained from the multi-physics calculations using Comsol software package. The pouch type LIB consisting of five distinct layers, i.e., two current collectors, negative and positive electrodes and electrolyte, is considered. The electrochemical model is based on a 1D continuum description of reaction and transport along electrodes, electrolyte and current collectors, plus an additional dimension in the electrode particle (P2D).1 The SEI formation/decomposition is modeled using the parasitic current approach.2,3 We investigate three regimes of thermal runaway occurrence, i.e., a single heat source, two heat sources and multiple sources. Correspondingly, different CNN and DNN architectures have been built and trained based upon the images from multi-physics calculations. The prediction of the trained network has been tested using simulated and literature available data.
References
[1] Newman, J.; Tiedemann, W. Potential and Current Distribution in Electrochemical Cells. J. Electrochem. Soc.
1993, 140 (7), 1–5.
[2] Wang, K.; Xing, L.; Zhi, H.; Cai, Y.; Yan, Z.; Cai, D.; Zhou, H.; Li, W. High Stability Graphite/Electrolyte Interface Created by a Novel Electrolyte Additive: A Theoretical and Experimental Study. Electrochimica Acta
2018, 262, 226–232. https://doi.org/10.1016/j.electacta.2018.01.018.
[3] Safari, M.; Morcrette, M.; Teyssot, A.; Delacourt, C. Multimodal Physics-Based Aging Model for Life Prediction of Li-Ion Batteries. Journal of the Electrochemical Society
2009, 156 (3), 145–153. https://doi.org/10.1149/1.3043429.
Lithium Deposition in Single-Ion Conducting Polymer Electrolytes
Authors: Borzutzki Kristina , Dong Kang , Nair Jijeesh Ravi , Wolff Beatrice , Hausen Florian , Winter Martin , Manke Ingo , Brunklaus Gunther 
Published: December 2020

Lithium metal is considered as potential anode material due to its superior energy density compared to conventional graphitic anodes.[1] However, so far its application is restricted due to inhomogeneous Li deposition during cycling, potentially causing contact losses between bulk and deposited Li or short circuit of the cell related to formation of ‘dendritic’ deposits. Theoretical models propose that single-ion conducting electrolytes afford safe and ‘dendrite-free’ cycling of lithium metal batteries (LMBs) due to immobilization of anions and thus, prevention of cell polarization.[2] In this contribution, a blend type quasi-solid single-ion conducting polymer electrolyte (SIPE), a polymer class that has attracted much attention recently, is consulted for analysis of the Li deposition behaviour. Combined scanning electron microscopy (SEM) and X-ray tomography are applied illustrating the occurrence of inhomogeneous, rather dense Li deposits agglomerating and eventually penetrating the polymer membrane independent of the applied current densities. Raman mapping, nano-mechanical (QNM) and electrochemical strain microscopy (ESM) mapping further reveal that membrane constituents and consequently membrane properties such as (mechanical) stiffness and ionic conductivity are non-homogeneously distributed within the membrane related to the phased separated morphology of the blend. This implies that the intrinsic nature of the polymer membrane is responsible for the formation of conduction channels, also governing the homogeneity of Li deposition. Beyond that, it is demonstrated how characteristics of the Li│polymer interface in salt- free SIPEs limit the achievable cell performance, particularly since limited Li+ ion diffusivity through the interfaces substantially impair efficient charge carrier transport within the cell system.

References

[1] P. Albertus, S. Babinec, S. Litzelman, A. Newman, Nat. Energy 3 (2018) 16–21.
[2] J.-N. Chazalviel, Phys. Rev. A 42 (1990) 7355–7367.
Understanding Anode Capacity Fade in Symmetric Cells
Authors: Yan Zilai , Liu Yijia , Hatchard Timothy , Scott Ben , Cao Yidan , Cao Simeng , Obrovac Mark N 
Published: December 2020

Symmetric cells have been developed to evaluate electrode degradation directly associated with solid electrolyte interphase (SEI) growth. This limits their applications to some certain anodes, such as graphite and Li4Ti5O12.1 In this work, symmetric cells have been applied to understand the degradation of high energy density anodes, such as Si-alloys, which undergoes multiple degradation mechanisms, including mechanical failure, SEI growth, and excess capacity. The excess capacity is related to the reversible capacity changes, caused by the electrode upper endpoint potential shift.
A Li inventory model is developed to interpret anode capacity fade in symmetric cells. The Li inventory model attempts to establish a mathematical relationship between multiple anode degradation processes and measured experimental data, such as cycling charge/discharge capacity. This model allows for the measurement of coulombic efficiencies of individual components of blended electrodes (e.g. alloy + graphite). Figure 1 illustrates the main reactions and side reactions during symmetric cell discharge at ith cycle. Except the main reactions in working electrodes about lithiation and delithiation, the side reactions, as mentioned above, have been included.
In this work, a Si-alloy, Si80W20,2 was used as an example. One major benefit of symmetric cells is to measure the coulombic efficiency (CE) of electrodes with standard chargers.3 After deconvolution, the total irreversible capacity (IC) per cycle due to surface reactions on Si80W20 can be obtained from graphite and Si-alloy/graphite blended electrodes. The temperature effects on IC can also be obtained, as summarized in Figure 2.

Reference

J. C. Burns et al., J. Electrochem. Soc., 158, A1417–A1422 (2011).

Y. Liu, B. Scott, and M. N. Obrovac, J. Electrochem. Soc. , 166, A1170–A1175 (2019) 10.1149/2.0851906jes.

Z. Yan and M. N. Obrovac, J. Electrochem. Soc., 164, A2977–A2986 (2017).

Figure 1 (a) An example of potential curves of electrode A, electrode B, and the symmetric cell during symmetric cell discharge. Illustrations of main and side reactions occurred at electrode A and electrode B during symmetric cell discharge at i
th cycle are illustrated in (b) and (c), respectively. The capacity for each reaction during a single symmetric cell discharge/charge process are labelled in the following brackets. Li-Eld, Eld, and Elyt stand for lithiated electrode, delithiated electrode, and electrolyte, respectively.

Figure 2 A summary of the average IC of graphite (MAG-E, 20 μm average size, Hitachi) and on Si80W20 per cycle normalized with respect to reversible capacity at different temperatures, as derived from symmetric cells with graphite and alloy/graphite blended electrodes.

Figure 1
Large-Area Graphene Transfer through Synthesis of an Interfacial Release Layer between Epitaxial Cu(Ni)(111) and Al2O3(0001) Template
Authors: Tsai Hung-Chieh , Marien Brecht , De Gendt Stefan , Brems Steven 
Published: December 2020

As the pioneer two-dimensional material with outstanding properties, graphene is still lacking a CMOS compatible handling process, both for growth and transfer. This restriction slows down the application of large-scale-high-quality monolayer graphene (MLG). The synthesis of wafer-scale single-crystal MLG has matured utilizing a single-crystal Cu(111) deposit epitaxially on c-plane sapphire as a growth template[1,2]. However, the non-straightforward intercalation base transfer process [3] becomes a bottleneck. Hence, an interfacial release layer between Cu and sapphire could provide an alternative route for the graphene transfer process.
Here, we report on the synthesis of large-area multilayer graphene at the interface of epitaxial Cu(Ni)(111)/ Al2O3(0001) using atmospheric pressure chemical vapor deposition (CVD). The interfacial carbon layer (ICL) was synthesized by introducing CH4 and H2 gases in the CVD chamber at 1050°C, and characterized by micro-Raman spectroscopy, XRD, and AFM. Carbon layers with thickness up to 80nm were observed at the interface between 500nm thick Cu and Al2O3.
The effects of the partial pressure of gases - PH2 and PCH4 – and template substrate on the growth dynamics were investigated systematically by optical microscopy and image analysis. The growth rate and deposition area of ICL are positively correlated with PCH4. In the Cu85Ni15(111) system, ICL coverage is significantly lower compared to Cu(111). This is attributed to the faster growth rate of a top surface MLG, which blocks the access of carbon into the interface of Cu(Ni)/Al2O3. A higher PH2 slows down the MLG growth, leading to a denser ICL deposition in both substrates.
The growth mechanism of this ICL is also proposed as the result of two competing effects: 1. The high PCH4 environment drives the decomposed carbon species to the interface from the top surface by diffusion through the bulk of the catalytic metal. 2. The blockage of carbon access to the bulk of metal once the top layer MLG is closed.
After process optimization, the ICL could be synthesized simultaneously with top layer high-quality CVD MLG. In the future, this process could provide opportunities to enable CMOS compatible large-scale-high-quality MLG transfer.

K. Verguts et al., ECS J. Solid State Sci. Technol., 5, Q3060–Q3066 (2016).

M. Huang et al., ACS Nano, 12, 6117–6127 (2018).

K. Verguts et al., ACS Appl.
Mater. Interfaces, 9, 37484–37492 (2017).
(Invited) Electrostriction Driven Preferential Solvation Processes for Divalent Cations in Non-Aqueous Electrolytes
Authors: Murugesan Vijay , Chen Ying , Han Kee Sung , Mueller Karl T 
Published: December 2020

The strong electric field from divalent cations (i.e. Mg2+, Zn2+ and Ca2+) can influence conformal structural evolution of organic solvent molecules and subsequently influence emergent properties of battery electrolyte solutions. This electrostriction process typically depends on the charge and size of the ion and on certain properties of the solvent such as molecular flexibility and permittivity. In this work, we focused on the effect of cationic size and structural flexibility of organic solvent molecules commonly used in multivalent batteries. In particular, we analyzed electrostriction driven preferential interactions that lead to contact-ion pair (CIP) and solvent separated ion pair (SSIP) formation in cyclic ether solvents such as tetrahydrofuran (THF) and 2-methyl-tetrahydrofuran (2-MeTHF) and linear structured ether solvents such as glymes (G1 and G2). The concentration and temperature dependent preferential interactions of these electrolyte systems were analyzed using multinuclear (1H,19F, 17O, 25Mg, 43Ca, and 67Zn) NMR spectroscopy and PFG-NMR diffusion measurement combined with classical MD and DFT based computational modeling. Our results show that the solvent-cation interaction is more favorable in the linear glyme-based electrolytes than in the cyclic THF-based electrolytes. In particular, the glyme-based solvents (G1 and G2) drive preferential dissociation of cation-anion pairs, resulting in a higher concentration of SSIPs in these multivalent electrolyte solutions. The correlation between such preferential solvation phenomena and emergent properties including conductivity and chemical stability will be discussed.
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