bluuebunny/crossref_metadata_2025 huggingface dataset:
Resisting Dendrites in Lithium Batteries, One Pinhole at a Time
Authors: Oyakhire Solomon , Zhang Wenbo , Cui Yi , Bent Stacey F.
Published: November 2022

For humanity to successfully transition from fossil fuels, the mismatch in the demand and supply of renewable energy must be addressed by reliable, high energy storage systems. One promising energy storage system is the lithium metal battery (LMB), owing to the high gravimetric capacity of lithium (3860 mAh/g). The potential gain in volumetric and gravimetric energy density offered by LMBs could usurp today’s lithium-ion battery technology and revolutionize energy storage. However, the lifetime of LMBs is hindered by morphological instabilities experienced during the electrodeposition of lithium.

Modifications of the solid electrolyte interphase (SEI) and electrolyte are the most common strategies for improving lithium metal morphology. However, electrolyte and SEI engineering are often tedious, based on trial and error, and insufficient for enhancing lithium electrodeposition. Here, we demonstrate a new, alternative strategy for controlling lithium metal morphology and improving electrochemical performance that is independent of the electrolyte and SEI. By modifying the current collector with atomic layer deposited (ALD) thin films of ZnO, SnO2, and Al2O3, we show that lithium deposits atop, rather than beneath, the thin films, resulting in changes in lithium morphology and battery performance that are strongly dependent on the electrical resistance of the ALD films. The results show that low resistance copper modification films like SnO2 and ZnO provide numerous sites for lithium nucleation and promote the formation of high surface area (fast electrolyte consuming) lithium deposits, while the highly resistive Al2O3-modified copper reduces the available sites for lithium nucleation and promotes the formation of low surface area (slow electrolyte consuming) clusters of lithium deposits.

We propose and demonstrate the first recorded mechanism for the connection between electrical resistance and lithium growth - we propose that, in resistive substrates, lithium metal nucleates atop only pinhole sites, then grows laterally by the radial diffusion of lithium ions from the electrolyte. We prove this mechanism analytically, using diffusion controlled current equations, and experimentally by introducing patterned pinholes into a resistive, pinhole-free substrate. We generalize the concept of resistance-controlled morphology and demonstrate high battery performance in three distinct classes of electrolytes, culminating in anode-free pouch cells that retain 60% of their initial discharge capacity after 100 cycles. This work presents a new approach for understanding the electrodeposition of lithium and tuning the performance of lithium metal batteries.
Characterizing Working Electrodes for in-Operando Spectroelectrochemical Cells Using Electrochemical Impedance Spectroscopy
Authors: Ganesan Akash , Zimudzi Tawanda J , Hall Derek M.
Published: November 2022

Increasing interest in spectroelectrochemisty due to its versatility and far-reaching applications has led to its rapid growth in recent years. Attenuated total reflectance (ATR), Fourier transform infrared spectroscopy (FTIR) is one technique that can provide valuable insights into surface interactions provided a viable working electrode can be fabricated. Though ATR working electrodes can be deposited using a range of techniques such as argon sputtering, vapor deposition and electrodeposition, published studies typically do not report electrode thicknesses which are a key in obtaining repeatable signal responses. Here we examine different approaches to quantify ATR electrode thicknesses and screen for optimal electrode configurations. The test system used to assess different approaches for validating electrode performance was the ferri-ferrocyanide redox reaction with an argon sputtered platinum surface. It was found that atomic force microscopy, ellipsometry and optical profilometry had practical limitations operating in the nanometer range and were not adequate for predicting spectroscopic outcomes. In contrast, electrochemical impedance spectroscopy (EIS) measurements accurately predicted high performing ATR working electrodes. For an 11 mm by 9 mm ATR wafer, favorable signal strengths corresponded to cell impedances greater than 500 Ω. Cell constant calculations determined that platinum thickness layers needed to be less than 4 nm to provide consistent spectroelectrochemical responses.
The Electrochemical Interface As a Reactive Environment to Re-Synthesize Electrode Surface Chemistry Using the Dissolution-Redeposition Dynamics
Authors: Hu Anyang , Lin Feng
Published: November 2022

The electrode-electrolyte interface governs the efficiency and life time of almost all electrochemical reactions. Essentially, this interface, as a geometrically confined environment, allows many interfacial reactions occurring and provides a versatile toolbox of tailoring electrode surface chemistry under operating conditions. Here, through synchrotron spectroscopic, microscopic, and imaging characterizations, using the electrochromic tungsten trioxide (WO3) in an acidic electrolyte as the research platform, we reveal that the performance degradation is related to electrode material morphology evolution, phase transformation, and charge heterogeneity. We experimentally demonstrate that WO3 dissolution and redeposition across the electrochemical interface trigger all these evolutions. The redeposition process provokes the in situ crystal growth, inducing the evolution from the semicrystalline WO3 to the single-crystalline, nanoflake-shaped, proton-trapped tungsten trioxide di-hydrate (H
x
WO3·2H2O). Importantly, as a ubiquitous phenomenon, transition metal dissolution will form the diffusion layer at the interface. We have established a novel experimental design to probe and understand how the dissolved transition metal species evolve in the diffusion layer. The thickness of the diffusion layer is up to tens of micrometers, and the local electronic structure of dissolved species varies with the distance from the electrode surface. Furthermore, this dynamic dissolution and redeposition feature can be manipulated to regulate the chemical composition and crystal structure of the electrode surface as well as the overall electrochemical performance. Foreign cations (e.g., Ti4+), either added as electrolyte additives or dissolved from surface coatings, can rapidly participate in the electrode dissolution-redeposition process and facilitate the establishment of the dissolution-redeposition equilibrium, thereby alleviating W net dissolution, modulating the electrode morphology, and improving the Coulombic efficiency and cycling stability during long-term electrochemical reactions. Therefore, our systematic study demonstrates that it is feasible to exploit the intertwined dissolution-redeposition kinetics between oxide surface coatings and electrodes in aqueous electrolytes to extend control over electrochemical interfacial reactions. Electrode surface chemistry can be re-synthesized in terms of regulating the dynamic structural evolution of electrode surface and the correlatively developing speciation at the interface, which highlights the significance of more fundamental investigations at the electrode-electrolyte interfaces.
In Situ Analytical Techniques: Solid Electrolyte Interface Analysis of Al Anode Materials for Al-Ion Batteries
Authors: Palanisamy Krishnaveni , Daboss Sven , Rahide Fatemehsadat , Dsoke Sonia , Kranz Christine
Published: November 2022

Rechargeable post Li-ion batteries based on aluminum (Al) are gaining attention due to high abundance of Al, the high theoretical volumetric capacity, and high safety associated with the low flammability [1,2]. In comparison to Li-ion batteries (LiBs), where the solid-electrolyte interphase (SEI) has been studied for decades, little is known on SEI formation in dependence of the used electrolyte for Al electrodes.

In this study, we present the electrochemical performance of Al foils with two different thicknesses (0.025 mm and 0.075 mm), which were used as negative electrode in Al-ion batteries in AlCl3/1-ethyl-3-methylimidazolium chloride [EMIm]Cl electrolyte. Atomic force microscopy (AFM) was used to determine changes in the morphology of Al foils during the charge - discharge process to obtain information on the SEI and its microstructural morphology [3]. Spatially-resolved information on the electrochemical activity of interphase layers on cycled Al foils can be obtained via scanning electrochemical microscopy (SECM), which so far has only be studied at LiBs [4]. First results reveal the correlation between the morphological changes of SEI layer during cycling and its electrochemical behavior depending on the Al foil surface properties, which will be presented and discussed in this contribution.

Key words: Al foil, AFM, microstructure, SEI layer, SECM.

References:

Meng-Chang Lin, Ming Gong, Bingan Lu, Yingpeng Wu, Di-Yan Wang, Mingyun Guan, Michael Angell, Changxin Chen, Jiang Yang, Bing-Joe Hwang and Hongjie Dai, Nature, 520, 325–328 (2015).

Li, and N.J. Bjerrum, J. Power Sources, 110, 1–10 (2002).

Feng Wu, Na Zhu, Ying Bai, Yaning Gao, and Chuan Wu, Green Energy & Environment 3, 71-77, (2018).

Bastian Krueger, Luis Balboa, Jan Frederik Dohmann, Martin Winter, Peter Bieker and Gunther Wittstock. ChemElectroChem,7, 3590–3596, (2020).

This work contributes to the research performed at CELEST (Center for Electrochemical Energy Storage Ulm-Karlsruhe) and was funded by the German Research Foundation (DFG) under Project ID 390874152 (POLiS Cluster of Excellence).
(Invited) On Several Atmospheric Pressure Plasma Sources
Authors: Lu Xinpei
Published: November 2022

In this talk, firstly, several plasma
jets
developed in our group
are
presented, including a nobble gas plasma jet for root canal treatment and four air plasma jet devices
[1, 2]
. Secondly, several interesting physics phenomena of plasma jets are introduced, such as the repeatability of the plasma bullet, the plasma interruption behavior, the plasma transfer dielectric phenomenon, and the appearance of multiple plasma bullet per voltage pulse
[2-4]
. Thirdly, the state-of-the-art on the measurement of VUV emission of atmospheric pressure air plasma is discussed and our results by using differential pumping system as EUV window are presented
[5]
.
Fourthly
, several different configurations of nonequal gap distance DBD are described
[6, 7]
.
Finally, an atmospheric pressure glow discharge in air stabilized by a magnetic field and its application on nitrogen fixation are
rep
orted.

Li, J. Liu, X. Lu, A large atmospheric pressure nonequilibrium open space air plasma based on a rotating electrode,P
lasma Sources Sci. Technol.
29, 045015 (2020)

Lu*, G. Naidis, M. Laroussi, K. Ostrikov, Guided ionization waves: Theory and experiments.
Physics Reports
, 540,123-166 (2014)

Lu*, and Kostya (Ken) Ostrikov, Guided ionization waves: The physics of repeatability,
Appl. Phys, Rev
,5, 031102 (2018)

Liu, L. Nie, Y. Xian, X. Lu*, The twisted behavior of a rotating electrode atmospheric-pressure argon plasma jet,
J. Phys. D: Appl. Phys.
54, 185201 (2021)

F Liu, L Nie, X Lu, J Stephens and K Ostrikov, Atmospheric plasma VUV photon emission,
Plasma Sources Sci. Technol.
29, 065001(2020)

Li, S. Jin, Y. Xian, L. Nie, D. Liu, X. Lu*, A non-equal gap distance dielectric barrier discharge: between a wedge-shaped and a plane-shaped electrode,
Plasma Sources Sci. Technol.
30, 065026 (2021)

Jin, Z. Li, Y. Xian, L. Nie, X. Lu*, A non‐equal gap distance dielectric barrier discharge: Between cone‐shape and cylinder‐shape electrodes,
High Voltage
, 1-9 (2021)
Multi-Harmonic Electrothermal Spectroscopy (METS), a New Technique for Spatially Resolved Electrochemical Measurements
Authors: Chalise Divya , Schaadt Joseph , Dhar Akshey , Srinivasan Venkat , Lubner Sean , Kaur Sumanjeet , Prasher Ravi
Published: November 2022

In this work, we introduce a new electrochemical technique, Multi-harmonic ElectroThermal Spectroscopy (METS) based on frequency dependent temperature sensing. We show that the thermal signatures generated at different harmonics when an Alternating Current (AC) is passed through an electrochemical cell can be used to extract thermodynamic (entropic), kinetic (charge transfer rate) and transport (charge and mass transport) properties associated with the electrochemical cell. From the frequency dependence of the thermal penetration depth, the spatial origin of the effect can be located within a resolution of a few microns, thereby enabling the attribution of the effect to a particular electrode. A four-point probe RTD sensor acting as a METS sensor is employed on the exterior of the current collector, which non-invasively provides spatially resolved information about the electrochemical processes in the cell. Through this work, we are able to, for the first time, determine the entropy change of a single charge transfer reaction in an electrode and spatially resolve the heat generation in a single Li-ion cell, with a length-scale resolution of a microns.
(Invited) Photophysics of QDs Enabled By Gas-Phase PECVD Growth
Authors: Neale Nathan R.
Published: November 2022

We have been exploring doping and alloying of semiconductor quantum dots (QDs) and the impact of chemical composition on the QD primary photochemical events including charge generation, separation, and recombination. Dopant incorporation and alloying without phase segregation are significant challenges using conventional colloidal growth methods. Nonthermal plasma-enhanced chemical vapor deposition (PECVD) growth is an attractive approach to overcome these challenges since it is controlled by kinetics rather than thermodynamics.

In this presentation, we will describe the PECVD synthesis of silicon quantum dots (Si QDs) that provides the ability to incorporate high concentrations (~1020 cm–3) of either p-type (B:Si) or n-type (P:Si) dopants. We also can use this synthetic technique to prepare co-doped QDs containing both P and B atoms in the same PB:Si QD. Whereas the optical absorption of singly P:Si and B:Si QDs exhibit plasmonic features characteristic of a high concentration of dopants, the co-doped PB:Si QDs instead exhibit photophysics that resemble those of intrinsic Si QDs, for example emission lifetimes of ~100 μs, but with size-dependent optical transitions that are tunable even below the energy of bulk Si (1.12 eV). Finally, we will describe new work on III–V semiconductors, in particular gallium nitride (GaN) QDs, that also exhibit tunable photophysics and serve as useful model systems for photochemically-driven small molecule conversion.
(Invited, Digital Presentation) Understanding the Self-Assembly of Polymer-Grafted Nanocrystals
Authors: Yun Hongseok
Published: November 2022

Combination of inorganic nanocrystals (NCs) and polymeric materials is promising for the design of novel functional materials due to their complementary properties. For the preparation of such hybrid nanomaterials with tailored functionalities, it is important to precisely control their nanostructures since material properties of NCs strongly depend not only on the morphology of each NC building block, but also their assembled packing symmetries. In this talk, I will present precise control of polystyrene-grafted Au NC (Au@PS) superlattice symmetry, which shows non-conventional assembly behavior compared to short alkyl chain-coated NCs. Au@PS NCs were synthesized by ligand exchange using thiol-terminated PS with various molecular weights (M
n). The Au@PS particles were self-assembled through liquid-air interface self-assembly process. Transmission electron microscopy images and grazing incidence small-angle X-ray scattering data indicated long-range ordered Au@PS superlattices. In particular, symmetry transitions from hexagonal close packing (hcp) to body centered cubic (bcc) symmetry were found as M
n of PS increases or diameter of NCs decreases. We tried to understand the structural transitions by proposing “effective softness” model, which considers concentrated polymer brushes around NC surface as part of “hard core.” Finally, I will show how these polymer-grafted NCs can be self-assembled with block copolymers for the development of colloidal hybrid particles with stimuli-responsive photoluminescence behavior, which have great potential for the applications in smart material systems.
(Invited, Digital Presentation) Excited State Properties of Low-Dimensional Materials: Insight By Ab-Initio DFT + Mbpt Simulations
Authors: Palummo Maurizia
Published: November 2022

The use of emerging low-dimensional materials in technological applications presupposes a detailed knowledge of their chemical and physical properties. In this context ab-initio theoretical methods and simulations are playing a fundamental role.

Here I aim to show how the use of parameter-free atomistic simulations can contribute to improve the microscopic understanding of the opto-electronic properties of nanomaterials and to predict new ones. I will show how ab-initio DFT and post-DFT (GW and BSE) calculations, based on Many-Body Perturbation Theory (MBPT), provide a very useful scheme to study i) giant electronic band-gaps renormalization due to low dielectric screening and large quantum confinement ii) strong light-matter interaction iii) fine structure of strongly bound excitons. iv) the influence of electron-phonon interaction on the electronic and optical spectra, v) how doping, molecular functionalization or strain can tune their opto-electronic properties. Main focus will be on different semiconducting 2D materials discovered after graphene, but other dimensionality examples will be discussed.
(Keynote) Quantum Dot Coatings for Aqueous Stabilization and Applications in Biomolecular Analysis
Authors: Smith Andrew M.
Published: November 2022

Semiconductor quantum dots have been commercially available as molecular probes for applications in the life sciences and clinical diagnostics for two decades, however they have only been adopted in niche applications. Part of the reason for limited adoption is attributable to challenges in colloidal stabilization, as these solid nanocrystals tend to aggregate and nonspecifically adsorb to surfaces and cellular structures. This can largely be alleviated by use of nanocrystal coatings that resist nonspecific binding and promote aqueous dispersion, however the vast majority of such coatings are based on neutral and zwitterionic polymers that add considerable hydrodynamic size to the product. This size increase is due to the bulk of the coating itself as well as adsorption of water molecules and ions in solution. The size increase causes steric hindrance and inaccurate molecular labeling when these probes are used to analyze targets that have considerable size or ones that are located in crowded regions of cells or tissues. Furthermore, the bioaffinity label that attaches the quantum dot to its intended molecular target often contributes substantially to the final size and stability of the probe. This is especially challenging for protein labeling using antibodies, which themselves are fairly large proteins that attach heterogeneously to quantum dots, typically yielding large, polydisperse products. This talk will focus on developments in quantum dot engineering, monolayer polymeric coatings, and bioconjugation strategies to optimize offsetting characteristics of size, homogeneity, bioaffinity, and specificity. In particular, multidentate polymer coatings in recent years have enabled the production of quantum dots with long-term shelf life, small hydrodynamic diameters, and efficient click chemistry conjugations. By tuning the conjugation methods to antibody fragments and single-stranded DNA, we can now prepare bioaffinity labels for proteins and nucleic acids in the ~10 nm range, with further size reductions possible through nanocrystal heterostructure engineering. This talk will also cover how in situ protein and nucleic acid labeling applications can benefit from these advances in addition to current challenges in processing, scale-up, and user adoption.
(Invited) Design and Synthesis of Colloidal QDs for Quantum Emitters
Authors: Fedin Igor
Published: November 2022

On-demand generation of quantum photons is one of the four major targets of Quantum Information Science (QIS), identified by the NSF as one of the five “industries of the future.” Colloidal semiconductor quantum dots (QDs) are viable candidates for quantum materials, owing to their tunable, bright, and stable emission. Identifying a suitable semiconductor material and engineering long exciton coherence times is key to producing single coherent photons on demand. We show that colloidal compositionally-graded CdSe/ZnS QDs designed with a high degree of asymmetric internal strain demonstrate superior quantum emission properties compared to conventional sharp-interface CdSe/ZnS QDs. In comparison to conventional colloidal CdSe/ZnS core/shell QDs, we find that, in asymmetrically strained CdSe QDs, over six times more light is emitted directly by the bright exciton. Temperature-dependent PL dynamics and fluorescence line narrowing (FLN) spectroscopy reveals the radiative recombination rates of bright and dark excitons, the relaxation rate between the two, and the energy spectra of the quantized acoustic phonons in the QDs that can contribute to relaxation processes. We attribute the six-fold improvement to the four-fold deceleration of the bright-dark relaxation and the doubled radiative recombination rate in the strained QDs.

The next step in this research is to bring these improvement from the visible to the near-IR emission, where most communication bandwidths lie. This area has been traditionally dominated by III-V materials, which are chemically challenging in the colloidal state. We design, synthesize, and characterize alternative strong near-IR materials and assess them as potential quantum emitters. Last but not least, we demonstrate applications of electrochemistry in programmable hot syntheses of colloidal QDs.
Optoelectric Properties of Doped Carbon Dot Nanostructures
Authors: Svrcek Vladimir , Dsouza Slavia Deeksha , Buerkle Marius , Padmanaban Dilli Babu , Maguire PAUL , Mariotti Davide
Published: November 2022

Carbon dots (C-Dots) can be defined as spherical-like carbon particles (graphitic fragments) with sizes less than 10 nm. Typically, C-Dots exhibit ample room temperature photoluminescence (PL) whereby the PL properties of C-Dots with a well-defined crystalline core is related to the size or conjugated domains of C-Dots accompany with contribution from the surface state, conjugated core, molecular configuration, and so on. However, up to date the exact mechanism of the PL origins of C-Dots depends on synthesis path and remains unsettled [1-3]. In this contribution we will discusses the synthesis, characterization and origins of PL properties of doped C-Dots their potential for applications as absorbers in solar cells. We discuss to use nitrogen doped C-Dots as active absorbing layer in a solar cell and how the electrical, optical, and chemical properties can be engineered by doping. We demonstrate that the doping can be efficiently used to modify the band structure of the C-Dots and meet the requirements for application in solar cells. To rationalize the measured experimental data, we also calculated using DFT in the sTDA approximation the absorbance spectra of pristine and nitrogen doped C-Dots. For computationally feasibility the diameter, d = 2.3 nm, of the C-Dots is chosen to be at the lower end of experimentally observed size distribution and the C-Dots consist of 3 carbon layers. Subsequently, these C-Dots have potential to be used as an absorbing material in next-generation solar cells for high energy photons to be absorbed by a lower bandgap transporter.

References:

Tetsuka , A. Nagoya , T. Fukusumi and T. Matsui , Adv. Mater., 2016, 28, 4632 —4638

.D. Mosconi , D. Mazzier , S. Silvestrini , A. Privitera , C. Marega , L. Franco and A. Moretto , ACS Nano, 2015, 9, 4156 —4164

Slavia Deeksha Dsouzaa, Marius Buerkle, Paul Brunet, Chiranjeevi Maddi, Dilli Babu Padmanaban, Alessio Morelli, Amir Farokh Payam, Paul Maguire, Davide Mariotti and Vladimir Svrcek, The importance of surface states in N-doped Carbon Quantum Dots、Carbon, 183, 1-11. (2021).
(Keynote) Photoinduced Charge Transfer from Quantum Dots Measured By Cyclic Voltammetry
Authors: Homer Micaela Kalmek , Kuo Ding-Yuan , Dou Florence Y , Cossairt Brandi Michelle
Published: November 2022

Measuring and modulating charge transfer processes at quantum dot interfaces are crucial steps in the development of quantum dot photocatalysis. In this work, cyclic voltammetry under illumination is demonstrated to measure the rate of photoinduced charge transfer from CdS quantum dots by directly probing the changing oxidation states of a library of model charge acceptors. The voltammetry data demonstrates the presence of long-lived electron donor states generated by native photodoping of the QDs as well as the relationship between driving force and rate of charge transfer. Changes to the voltammograms under illumination follow mechanistic predictions from classic zone diagrams and electrochemical modeling allows for measurement of the rate of productive electron transfer, giving rate constants (104 M-1s-1) that are distinct from the ps dynamics measured by conventional optical spectroscopy methods and that are more closely connected to the quantum yield of photoinduced chemical transformations.
Higher Energy Density Mediated Lithium-Sulfur Flow Batteries
Authors: Meyerson Melissa L , Maraschky Adam M. , Small Leo J.
Published: November 2022

There is a need for safe, reliable, high-capacity storage for long duration energy storage. The low cost and high capacity of sulfur make Li-S batteries ideal for this purpose. However, sulfur has poor electrical conductivity and Li-S batteries are prone to polysulfide shuttling that decreases the battery life. Additionally, lithium metal cannot be cycled at high rates or dendritic growth is produced. We have previously addressed the issues with the S by combining aspects of a static Li-S battery with aspects of a redox targeting system and flow battery. With this system we demonstrated that fundamental Li-S chemistry and novel SEI engineering strategies can be adapted to the hybrid redox flow battery architecture, obviating the need for ion-selective membranes or flowing carbon additives, and offering a potential pathway for inexpensive, scalable, safe MWh scale Li-S energy storage. However, these tests were done at lab scale with low S loadings and limited charge rates, limiting both the energy and power density of the proof-of-concept system. In this study we present recent progress scaling up the system from 2.5 mgS cm-2 to over 50 mgS cm-2 and increasing the current density from 0.5 mA cm-2 to 10 mA cm-2 to decrease the charge/discharge time. The increase in S loading results in an increase in energy density and the increase in applied current increases the power density of the system.

To scale up the flow cell we address limitations of the small-scale architecture including examining the flow field used with the catholyte and the structure of the Li metal anode. We first tested high surface area scaffolds in Swagelok cells to examine the effect of the increased effective surface area and seeding with lithiophilic materials, like ZnO, on Li metal deposition independent of the flow cell or S chemistry. Using a high effective surface area anode support enables us to increase the applied current density from 0.5 mA cm-2 to 10 mA cm-2 greatly increasing the charge/discharge speed. Furthermore, the addition of a lithiophilic seed layer decreases the nucleation overpotential and encourages uniform Li electrodeposition. A tailored flow field also improves the uniformity of Li deposition on the anode by improving the uniformity of the catholyte flow velocity. These improvements are first evaluated separately and then combined in a mediated Li-S flow battery where cycling rate and capacity retention are compared against a traditional planar Li anode and open flow field.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Simulation Strategies for Measuring Impedance Response of Lithium-Ion Batteries
Authors: Telmasre Tushar Khemraj , Jang Taejin , Goswami Neha , Concepcion Anthony , Subramanian Venkat R.
Published: November 2022

The battery as an electrochemical system can be considered a Blackbox with no way of observing processes occurring within it in a nondestructive manner1. However, most physical, and chemical processes in electrochemical systems are shown to be distinguishable by their distinct characteristic time constant. Electrochemical impedance spectroscopy (EIS) can therefore be a valuable tool to distinguish between internal processes within batteries based on their frequency response2–4.

Numerical approaches for understanding battery systems have long been explored by researchers in academia and industry alike2,4,5. Generally, it is computationally expensive to develop a high fidelity multiscale and multiphysics model with high predictive capability that can estimate critical transport parameters and material decay. Thus, model development traditionally starts with simplistic models where more physics is added as per requirements. Many approaches to mathematical modelling of the battery at different length scales and complexity are available today6.

The impedance response of the battery can also be simulated coupled with various other parameters using the battery models7. Basic equivalent circuit models of the battery are commonly used for this but they suffer from lack of physical interpretability and model degeneracy8. The impedance response based on models are obtained in a physics-based model by linearizing the non-linear models and transforming equations in the time-domain into the frequency domain5,9. This generally is achieved by applying a Laplace transform to the system of linearized equations. Now, based on the complexity of the model, these equations can be solved analytically or after separating the real and imaginary parts for numerical simulation.

Therefore, there are varied solution strategies appropriate for individual battery models that depend on underlying scale and physics involved. Through this work we aim to comprehensively compile these solution strategies and present the best approach for the individual electrochemical model based on criteria such as faster convergence times and error minimization.

References:

R. S. Robinson, INTELEC, Int. Telecommun. Energy Conf., 654–661 (1996).

M. Gaberšček, Nat. Commun., 12, 19–22 (2021).

J. Xu, C. C. Mi, B. Cao, and J. Cao, J. Power Sources, 233, 277–284 (2013).

S. E. Li, B. Wang, H. Peng, and X. Hu, J. Power Sources, 258, 9–18 (2014).

J. P. Meyers, M. Doyle, R. M. Darling, and J. Newman, J. Electrochem. Soc., 147, 2930 (2000).

V. Ramadesigan et al., J. Electrochem. Soc., 159, R31–R45 (2012).

D. Andre et al., J. Power Sources, 196, 5349–5356 (2011).

S. Fletcher, J. Electrochem. Soc., 141, 1823–1826 (1994).

M. Pathak et al., J. Electrochem. Soc., 165, A1324–A1337 (2018).
Insights into the Lithium Nucleation and Plating/Stripping Behavior from Ionic Liquid-Based Battery Electrolytes
Authors: Stepien Dominik , Wolff Beatrice , Diemant Thomas , Kim Guk-Tae , Hausen Florian , Bresser Dominic , Passerini Stefano
Published: November 2022

Lithium-metal batteries are anticipated to become the next-generation battery technology, allowing for substantially higher energy densities. To maximize the energy density, however, a “zero excess” of lithium in the cell is a must, e.g., by initially storing all electrochemically active lithium in the positive electrode.1 Nevertheless, this requires the fully reversible deposition of metallic lithium, i.e., a Coulombic efficiency of essentially 100%.2

Herein, the investigation of the lithium nucleation and plating/stripping from ionic liquid-based electrolytes composed of N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) on nickel current collectors is reported, involving a comprehensive set of electrochemical techniques coupled with operando and in situ atomic force microscopy and ex situ X-ray photoelectron spectroscopy. It was found that the morphology of the deposited lithium, the chemical composition of the interphase formed on the nickel current collector, and the reversibility of the lithium plating and stripping is highly dependent on the ratio of the ionic liquid and the lithium salt. Moreover, the addition of suitable film-forming additives allows for lower overpotentials and greater reversibility by tuning the interphase composition. The results are anticipated to contribute to the development of advanced electrolyte systems for “zero excess” lithium-metal batteries.

(1) Nanda, S., Gupta, A., and Manthiram, A. Anode-Free Full Cells: A Pathway to High-Energy Density Lithium-Metal Batteries. Adv. Energy Mater.
2021, 11, 2000804. DOI: 10.1002/aenm.202000804

(2) Hobold, G.M., Lopez, J., Guo, R. et al. Moving beyond 99.9% Coulombic efficiency for lithium anodes in liquid electrolytes. Nat. Energy
2021, 6, 951–960. DOI: 10.1038/s41560-021-00910-w
Lithium Solvation and Mobility in Asymmetric Cyano(trifuloromethanesulfonyl)Imide Based Ionic Liquid Electrolyte for Li-Metal Battery
Authors: Penley Drace , Wang Xiaoyu , Garaga Mounesha N , Lee Yun-Yang , Ghahremani Raziyeh , Greenbaum Steven , Maginn Ed , Gurkan Burcu E
Published: November 2022

The solvation structure and transport properties of Li+ in ionic liquid (IL) electrolytes based on n-methyl-n-butylpyrrolidinium cyano(trifluoromethanesulfonyl)imide [PYR14][CTFSI] and [Li][CTFSI] (0≤ xLi ≤ 0.7) were studied by Raman and Nuclear Magnetic Resonance (NMR) spectroscopy, and molecular dynamics (MD) simulations. Li+-anion coordination is found to be dominated through the cyano group. Coordination through the sulfonyl group is seen only at higher Li-salt concentrations (xLi > 0.3). Such a trend is not observable in the case of the analogous electrolyte composed of the 1:1 mixture of the symmetric anions bis(trifluoromethanesulfonyl)imide ([TFSI]) and dicyanamide ([DCA]) since the Li-salt concentration was limited by its solubility (xLi < 0.05). The calculated ion pair lifetimes of Li+-cyano coordination for [CTFSI] are found to be shorter than that of [DCA] at xLi = 0.05, indicating the competition from the sulfonyl group on [CTFSI] weakens its solvation with Li+. This translated to the higher Li+ transference estimated for the IL electrolyte with [CTFSI] in comparison to [TFSI]:[DCA]. The NMR diffusivity measurements indicated an increase in Li+ diffusivity compared to [CTFSI] as xLi approached 0.7. These findings suggest the Li+ transport mechanism changes in the asymmetric anion at high salt concentrations. In relation to the utility of these electrolytes in energy storage, the Li-LiFePO4 half cells assembled with IL electrolyte were tested at 363 K. The system with xLi=0.7 demonstrated a capacity retention of 61% at 0.1 C-rate and 363 K after 100 cycles; remarkably higher than those of xLi=0.3 and 0.5. This is attributed to the improved electrochemical stability of the IL electrolyte with the asymmetric anion at higher salt concentrations.
Tailored Electrolytes for New Redox-Active Polymers
Authors: Su Po-Hua , Asenbauer Jakob , Baumert Marcel , Le Victoria , Voll Dominik , Hansmann Max , Theato Patrick , Bresser Dominic
Published: November 2022

Radical polymers are gaining increasing interest as active materials for batteries owing to their great potential for fast charging, and the fact that no critical elements are involved. PTMA [poly(2,2,6,6- tetramethylpiperidinyloxy-4-yl methacrylate)] is one of the best-investigated radical polymers for lithium batteries, providing high redox activity, fast kinetics and great reversibility during cycling.1 However, the electrochemically active nitroxyl radicals are embedded in a six-membered ring with four methyl groups attached to stabilize the radical, which limits its theoretical capacity due to the rather high molecular weight of the overall functional moiety. To increase the theoretical capacity, a decrease of the “unnecessary” mass is therefore desirable. Smaller redox-active molecules, however, commonly show a high solubility in liquid electrolytes, which prevents stable long-term cycling.

Herein, we present a new redox-active polymer based on low molecular weight amides, for which the solubility issue has been overcome by proper design. We show that the electrolyte composition (salt concentration and the choice of solvents as well as their ratio) plays a decisive role for (i) the redox behavior and kinetics (broad vs. sharp redox peaks and the redox peak separation), (ii) the eventual redox potential, which is greater than for PTMA, and (iii) the long-term stable cycling at high dis-/charge rates. As a result, the rational optimization of the electrolyte composition enables achieving excellent electrochemical performance, rendering this new class of polymers highly promising for high-performance rechargeable batteries. Finally, we unveil the underlying phenomena by means of complementary ex situ and in situ characterization techniques to provide an in-depth understanding and, thus, allow for the tailored design of suitable electrolyte compositions for this new class of redox-active polymers and, potentially, polymer electrode materials in general.

(1) Kim, J.-K.; Kim, Y.; Park, S.; Ko, H.; Kim, Y. Encapsulation of Organic Active Materials in Carbon Nanotubes for Application to High-Electrochemical-Performance Sodium Batteries. Energy Environ. Sci.
2016, 9 (4), 1264–1269. https://doi.org/10.1039/C5EE02806J.
(Invited) Developing Titanate Anodes for Sodium Ion Batteries
Authors: Doeff Marca M. , Yin Wei , Barim Gozde
Published: November 2022

Sodium titanates are among the most promising anode materials for sodium ion batteries, due to their low cost, possibility of high tap density, and relatively higher operation voltage compared to commonly used hard carbons that prevents metallic sodium plating. 1 However, these oxides have a finite number of sites for ion insertion, which limits the Na+storage capacity, and thereby the achievable energy density. The sluggish Na+ (de)intercalation kinetics and poor electronic conductivity are other impediments to the practical capacity and rate capability. The presence of mobile cations (e.g., Li+) instead of less mobile ones (e.g., Mg2+) in the metal oxide layers was shown to provide additional diffusional pathways for Na+ and improves the practical capacities.2 This observation motivated us to design and synthesize lepidocrocite-structured titanates with vacancies in the metal oxide layers, on the assumption that these vacancies will have similar beneficial effects as mobile cations.3 These non-stoichiometric titanates do indeed show improved capacities, due to the additional sites in the metal oxide layers, and, possibly, some surface contributions to the redox behavior. To overcome kinetic limitations, large amounts of carbon additives are often used to improve electrical conductivity in the electrode composites. However, it is possible to manipulate the titanate structure instead, by incorporating conductive carbon between the metal oxide layers to overcome the electronic limitations. To this end, we have designed and synthesized heterostructures of lepidocrocite titanates.4 Carbon-free composite electrodes containing these heterostructures outperform conventional titanate electrodes containing carbon, illustrating the principle.

References:

Rudola, A.; Rennie, A. J. R.; Heap, R.; Meysami, S. S.; Lowbridge, A.; Mazzali, F.; Sayers, R.; Wright, C. J.; Barker, J., Commercialisation of high energy density sodium-ion batteries: Faradion's journey and outlook. Journal of Materials Chemistry A
2021,
9 (13), 8279-8302.

Markus, I. M.; Engelke, S.; Shirpour, M.; Asta, M.; Doeff, M., Experimental and Computational Investigation of Lepidocrocite Anodes for Sodium-Ion Batteries. Chemistry of Materials
2016,
28 (12), 4284-4291.

Yin, W.; Alvarado, J.; Barim, G.; Scott, M. C.; Peng, X.; Doeff, M. M., A layered nonstoichiometric lepidocrocite-type sodium titanate anode material for sodium-ion batteries. MRS Energy & Sustainability
2021.

Barim, G.; Dhall, R.; Arca, E.; Kuykendall, T. R.; Yin, W.; Takeuchi, K. J.; Takeuchi, E. S.; Marschilok, A. C.; Doeff, M. M., Heterostructured Lepidocrocite Titanate-Carbon Nanosheets for Electrochemical Applications. ACS Applied Nano Materials
2021,
5 (1), 678-690.
Statistical Approach to Design Zn Particle Size, Shape, and Crystallinity for Alkaline Batteries
Authors: Lenhart Brian , Zuraw Michael , Mustain William Earl
Published: November 2022

The modern alkaline primary battery is composed of a highly alkaline, gelled electrolyte-zinc powder anode dispersion (slurry), a cellulose-based separator, and an electrolytic manganese dioxide (EMD) cathode pellet – typically arranged in a cylindrical cell geometry. This battery system has its origins in the 1950s and thus has had decades to be researched and matured and it is known that the limiting performance of this battery system is concentrated at the slurried zinc anode. This had led many researchers to focus on the anode for improvement with most previous engineering efforts targeting enhanced performance, capacity, and stability of this material. Due to the various material fabrication processes involved with manufacturing industrial zinc powder, there exists an array of unique zinc particle size, shape, and crystallinity combinations that distinguish industrial zinc powders from one another. These industrial zinc powders are typically produced through trial-and-error processes using existing “rules of thumb”. Consequentially, it is possible that something has been missed and a data-driven approach could elucidate the optimum combination of zinc particle properties.

In this study, we investigate the effect of Zn particle size, shape, and degree of crystallinity on the achievable capacity and corrosion current. Various types of zinc powders were sieved into size fraction ranges and chemically and thermo-chemically treated to control their crystallinity. The procedure for producing zinc powders of various sizes, shapes, and crystallinities led to a 64-powder Zn matrix that was then electrochemically analyzed by linear sweep voltammetry to determine the corrosion current and galvanostatically discharged to determine the achievable capacity. These experiments were done in a newly-designed, custom-built electroanalytical cell that will be described in the talk. Following the data collection, a 4k factorial statistical analysis was performed. This analysis identified which of the controlling variables have a statistically significant influence on the achievable capacity and corrosion. The statistical model was also able to provide guidance regarding the preferred particle shape. This information can be used to develop actionable procedures for battery manufacturers to create cells that are more stable, longer lasting, and have higher energy densities.
(Invited) Towards First-Principles Prediction of Early SEI Formation
Authors: Persson Kristin A.
Published: November 2022

Despite decades of work, there is still considerable uncertainty regarding the major components of the solid-electrolyte interface (SEI) and its dynamic formation mechanism as a function of electrolyte and anode composition. Here we present a new data-driven first-principles framework using a combination of high-throughput calculations, reaction networks, machine learning and microkinetic modeling. Our automated methodology is based on a systematic generation of relevant species using a general fragmentation/recombination procedure which provides the basis for a vast thermodynamic reaction landscape, calculated with density functional theory. We explore this landscape using stochastic methods and shortest pathfinding algorithms, which yield the most likely reaction pathways which are then refined with transition state calculations and kinetic information. The results of the framework show promise in being able to automatically recover previous insights on single reaction pathways, as well as successfully predicting the early dynamics and competitive nature of the SEI formation. As examples, we present formation mechanisms of LEMC as compared to LEDC and recover the Peled-like separation of the SEI into inorganic and organic domains resulting from rich reactive competition. By conducting accelerated simulations at elevated temperature, we track SEI evolution, confirming the postulated reduction of lithium ethylene monocarbonate to dilithium ethylene monocarbonate and hydrogen gas. These findings furnish fundamental insights into the dynamics of SEI formation and demonstrate a path forward toward a predictive understanding of electrochemical passivation.
(Invited) Calendar Life Prognosis in Si-Containing Li-Ion Batteries
Authors: Johnson Christopher S.
Published: November 2022

Because of their high-gravimetric capacities, use of Si-containing anodes in Li-ion batteries can lead to a big jump in energy densities. The calendar life of Si in these batteries however is difficult to prognose and try to extend because of the highly chemical reactivity of lithium silicides at high states of charge (SOC). The control of lithium consumption and loss of inventory to solid electrolyte interphase (SEI) growth (and re-growth), and potential impedance growth contributes greatly to the shortened calendar life of, perhaps, one year to 80% energy retention. There is a US Department of Energy DOE program (Silicon Consortium Project or SCP) that currently is confronting the basic and applied science problems of Si with the hopes of developing > 10 year calendar life for Si-containing cells. We have been developing a constant voltage testing protocol using LFP/Si cells in order to ascertain the irreversible capacity amount associated with the chemical and electrochemical side reactions on the Si side of this system. However, due to the slow Li-Si electrochemical equilibrium kinetics, continuing reversible lithiation results for 100s of hours, and thus a semi-quantitative estimate of the calendar life is not feasible. Reference performance tests (RPT) with capacity checks every month at some fixed SOC and temperature continue to provide the most reliable indicator of calendar life. We believe that the voltage hold tests do provide a qualitative solution or stage-gate to continuation of pursuit of solutions to calendar life limitations. In this presentation, I will discuss these issues and provide some solutions to partly solve the short calendar life of Si together with models to estimate the future life.
(Invited) Perspectives on the Impact of Interfacial Interactions and Ion/Electron Transport for Robust Energy Storage Solutions
Authors: Gonzalez Miguel , Gueon Donghee , Renderos Genesis , Marschilok Amy C. , Takeuchi Kenneth J. , Takeuchi Esther S. , Reichmanis Elsa
Published: November 2022

Over the past decade, conversion-type anodes have been viewed as an attractive alternative for use in the next-generation of high capacity battery materials. However, many technological limitations exist in the stability and long-term reliability of these anodes for the commercialization of these electrodes. Here, we explore the complex interfacial interactions between the components of composite electrodes along with the impact of the chemical/electrochemical environment on performance. Fundamental insight into the factors that influence ion and electron transport within the composite systems are expected to help elucidate the key physical and chemical properties needed for the development of high-capacity materials for battery applications.