bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Multiscale Co-Simulation Modeling Technique to Understand the Transports Interaction inside Gas Channel, GDL, MPL, and CL during PEMFC Operations
Authors: Shimpalee Sirivatch , Satjaritanun Pongsarun , Hirano Shinichi , Zenyuk Iryna V. , Weidner John W.
Published: February 2020

The objective of this study is to use coupled simulation (co-simulation) approach to model the multidimensional/multiscale/multiphase polymer electrolyte membrane fuel cell (PEMFC) for enhancing the understanding of fuel cell performance and durability implications with structural, material properties and operational conditions. This work also provides the detailed knowledge of transports inside gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL). The local kinetic activity inside nanoscale CL has also been developed and modeled. These knowledge will contribute to enhance the catalyst activity at low current density and mass transport at high current density. This will enrich the development of novel structures that address local oxygen transport resistance in any kind of catalyst layer and this will be well aware of the urgent need for investigating multi-scale phenomena of a physical and electrochemical nature in a fuel cell.

The Lattice Boltzmann Method (LBM) approach is extended to solve the mass transports and kinetic in the CL as shown in Figure 1. In this figure the catalyst layer is included into the model established in the previous work [1-3]. The nanoscale catalyst layer is attached into the microscale gas diffusion layer (GDL) and micro porous layer (MPL) as one computational domain. The macroscale geometry such as flow channel is continued to be computed by conventional CFD [4-5]. Figure 2 shows example of predictions of temperature distribution and oxygen mass fraction inside the cathode macroscale flow-field channel, microscale GDL/MPL, and nanoscale CL from this co-simulation approach.

References:

Satjaritanun et al., J. Electrochem. Soc. 164(11) E3359-E3371, 2017.

Satjaritanun et al., J. Electrochem. Soc. 165(13), F1115-F1126, 2018.

Shimpalee et al., Abstract# I01A-1369, AiMES 2018, Sept. 30 – Oct. 4, 2018, Cancun, Mexico.

Shimpalee et al., J. of Electrochem. Soc. 165 (11), F1019-F1026, 2018.

Shimpalee et al. J. of Electrochem. Soc., 164(11), E3073-E3080, 2017.

Figure 1
Mass-Transport Resistances of Acid and Alkaline Ionomer Layers: A Microelectrode Study Part 1 - Microelectrode Development
Authors: Petrovick John G. , Kushner Douglas I. , Tesfaye Meron , Danilovic Nemanja , Radke Clayton J. , Weber Adam Z.
Published: February 2020

One of the most critical issues limiting widespread commercialization of polymer-electrolyte fuel cells is catalyst cost, which is directly related to dominant unexplained local gas and ion transport resistances at low catalyst loading (1). These resistances are believed to be highly correlated to the ionomer thin films in the catalyst layer. Unfortunately, current understanding of transport resistances in the catalyst layer is largely inferred from limiting current experiments employing heterogeneous, complex and multi-interfaced membrane electrode assemblies. An alternative study providing a more localized probe and promising fundamental insight is the microelectrode method (2). Ionomer thin film-coated microelectrodes can simulate an idealized thin film operating condition similar to that found at the platinum/ionomer interface in the catalyst layer of a typical fuel cell. In this work, an in-house, custom-made microelectrode setup with good humidity, temperature and potential control is used to determine the transport coefficient of hydrogen and oxygen gas across the ionomer thin film layer. The set-up is also capable of examining gas transport and evaluating the impact of ion activity on electrochemical kinetics in both acid and alkaline conditions, making it ideal for expanded understanding of gas and ion transport in both polymer electrolyte membrane and alkaline anion exchange fuel cells, respectively.

A. Z. Weber and A. Kusoglu, J. Mater. Chem. A., 2, 17207 (2014).

D. Novitski and S. Holdcroft, ACS Appl. Mater. Interfaces, 7, 27314 (2015).

Acknowledgements: This study was partially funded under the Fuel Cell Performance and Durability Consortium (FC-PAD) funded by the Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U.S. Department of Energy under contract number DE-AC02-05CH11231.
Understanding Polymer/Particle Interactions in Fuel-Cell Inks Using Model Systems
Authors: Berlinger Sarah A. , McCloskey Bryan D. , Weber Adam Z.
Published: February 2020

The formation process of hydrogen fuel-cell catalyst layers (CLs) is poorly understood, and represents a major area of effort with regard to increasing overall cell efficiency and durability. CLs are made from precursor inks that are dispersions of catalyst nanoparticles, ion-conducting polymer, and solvent (typically water and propanol mixtures). The polymer is generally a perfluorinated sulfonic-acid polymer, the prototypical example of which is Nafion. The duality between the strongly acidic sidechains and hydrophobic backbone of the polymer cause it to adopt unique conformations in solution, which are a strong function of the amount of water present in the ink.1 Indeed, tuning the ratio of water to propanol has recently been demonstrated to change the effective pH of these polymer solutions, possibly by changing the amount of exposed sidechains.2

The complex interplay between particle/solvent/polymer interactions govern CL ink and layer properties.3-4 However, much remains unknown about the fundamental forces controlling these interactions. In this study, we explore the polymer/particle interaction, and how it is affected by solvent quality. To do so, we use quartz crystal microbalance with dissipation (QCM-D) with model functionalized substrates that probe specific relevant forces (electrostatic, hydrophobic, etc.) in order to elucidate interactions present on the comparably more-complex carbon-platinum particle surface. Different ionomer dispersions in a variety of solvents are studied to understand ionomer adsorption and desorption behavior. QCM-D data is coupled with calorimetry measurements to extract thermodynamic binding information. Results reveal that hydrophobic interactions are a major driving force for ionomer adsorption.

Acknowledgements

This study was mainly funded under the Fuel Cell Performance and Durability Consortium (FC-PAD) funded by the Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U.S. Department of Energy under contract number DE-AC02- 05CH11231. S.B. also acknowledges support from the National Science Foundation Graduate Research Fellowship under grant number DGE 1752814.

References

Welch, C.; Labouriau, A.; Hjelm, R.; Orler, B.; Johnston, C.; Kim, Y. S., ACS Macro. Lett.
2012,
1 (12), 1403-1407.

Berlinger, S. A.; McCloskey, B. D.; Weber, A. Z., J. Phys. Chem. B.
2018,
122 (31), 7790-7796.

Dixit, M. B.; Harkey, B. A.; Shen, F.; Hatzell, K. B., J. Electrochem. Soc.
2018,
165 (5), F264-F271.

Hatzell, K. B.; Dixit, M. B.; Berlinger, S. A.; Weber, A. Z., J. Mater. Chem. A
2017,
5 (39), 20527-20533.
Modeling Water Uptake and Pt Utilization in High Surface Area Carbon
Authors: Chowdhury Anamika , Darling Robert M. , Radke Clayton J. , Weber Adam Z.
Published: February 2020

Reducing the loading of expensive Pt-based catalysts in polymer-electrolyte fuel-cell (PEFC) catalyst layers (CLs) is imperative for wide-scale commercialization. However, a local resistance close to the Pt reaction sites becomes significant at low Pt loadings and hinders adequate performance.1,2 In our previous study, we demonstrated that the local resistance is primarily related to the proton-conducting ionomer thin-film within the CL and consists of: (i) reactant transport resistance due to low permeability of ionomer thin-film (compared to bulk ionomer) and (ii) interfacial resistance due to Pt/sulfonic-moiety interactions.3 Thus, there is need to optimize ionomer design to minimize CL resistance.

In this talk, we investigate the impact of ionomer chemistry, content, and equivalent weight (EW) on CL resistance. Using H2 limiting-current measurements, the total CL resistance is segregated into transport and interfacial components. CL resistance increases monotonically with ionomer content, primarily due to thicker ionomer films. Low EW ionomers demonstrate higher interfacial resistance due to high density of sulfonic groups, whereas higher EW ionomers exhibit higher transport resistance due to low-reactant permeability associated with low-water uptake. These findings are rationalized through comparison of properties and structure/function relationships elucidated by ionomer thin-film studies on planar substrates, thus bringing together model and in-situ studies.

Further, time-permitting, the impact of carbon support (low versus high surface area carbon) on local CL resistance will also be discussed, mainly via modeling water uptake and proton pathways. Overall, the knowledge gained demonstrate pathways towards ameliorating the local resistance and enabling high performing low Pt-loaded PEFCs.

Acknowledgements

We would like to thank Sarah A. Berlinger and Robert Darling for helpful discussions. This work was funded under the Fuel Cell Performance and Durability Consortium (FC-PAD) funded by the Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U. S. Department of Energy under contract number DE-AC02-05CH11231.

References:

1. T. A. Greszler, D. Caulk and P. Sinha, J Electrochem Soc, 159, F831 (2012).

2. A. Z. Weber and A. Kusoglu, J Mater Chem A, 2, 17207 (2014).

3. T. Schuler, A. Chowdhury, A. T. S. Freiberg, B. T. Sneed, F. B. Spingler, M. C. Tucker, K. More, C. J. Radke and A. Z. Weber, J Electrochem Soc, 166, F3020 (2019).
Towards Electrochemical Synthesis of Cement — an Electrolyzer-Based Process for Decarbonating CaCO3 while Producing Useful Gas Streams
Authors: Ellis Leah , Badel Andres F , Chiang Miki , Park Richard , Chiang Yet-Ming
Published: February 2020

Cement production is currently the largest single industrial emitter of CO2, accounting for 8% (2.8 Gtons/year) of global CO2 emissions in 2015. Deep decarbonization of cement manufacturing will require remediation of both the CO2 emissions due to the decomposition of CaCO3 to CaO, and that due to combustion of fossil fuels (primarily coal) in the calcining (~900°C) and sintering (~1,450°C) processes. Here, we demonstrate an electrochemical process that uses neutral water electrolysis to produce a pH gradient in which CaCO3 is decarbonated at low pH and Ca(OH)2 is precipitated at neutral to high pH, concurrently producing a high purity O2/CO2 gas mixture (1:2 molar ratio at demonstrated stoichiometric operation) at the anode and H2 at the cathode, as shown in Figure 1. We show that the solid Ca(OH)2 product readily decomposes and reacts with SiO2 to form alite, the majority cementitious phase in Portland cement. Our electrochemical calcination approach produces concentrated gas streams from which the CO2 may be readily separated and sequestered, the H2 and/or O2 may be used to generate electric power via fuel cells or combustors, the O2 may be used as a component of oxyfuel in the cement kiln to further lower CO2 and NOx emissions, or the output gases may be used for other value-added processes including liquid fuel production. Analysis shows that in a scenario where the hydrogen produced by the reactor is combusted to heat the high temperature kiln, the electrochemical cement process can be powered solely by renewable electricity.

Figure 1. Schematic of the electrolyzer-based decarbonation cell. Reactions 1a and 1b are the O2 evolution and H2 evolution half-cell reactions respectively, under near-neutral pH. Reactions 2a and 2b represent the decomposition of CaCO3 and release of CO2. Reaction 3 is the normal formation of water from its component ions. In Reaction 4, the hydroxide ions in Reaction 3 instead go towards the formation of Ca(OH)2, and the protons protonate carbonate ions (Reaction 2b). The overall reaction in which CaCO3 is converted to Ca(OH)2 with the attendant release of H2, O2 and CO2 is shown at the bottom.

Figure 1
Characteristics of Metallic Bipolar Plate for Polymer Electrolyte Membrane Fuel Cells
Authors: Pilinski Nadine , Nagappan Nambi Krishnan , Wagner Peter , Dyck Alexander
Published: February 2020

The bipolar plate is one of the most significant key components in polymer electrolyte membrane fuel cells (PEMFCs). Bipolar plate (BPP) weight and cost are determining factor for future commercialisation of PEMFC technology. To overcome this major hurdle, metallic bipolar plates are used as a BPP in large number of commercial PEMFCs due to their advantages such as excellent mechanical strength, good electrical and thermal conductivities, low cost, ease of fabrication, gas impermeability, and possibility to make thin plates [1, 2]. However, corrosion remains a major anxiety for metallic bipolar plates use in real PEMFC operating conditions. Further, the formation of passivation layers reduces not only the electrical conductivity but also the overall performance. The aim of this present research is to characterise metallic bipolar plate with respect to corrosion behaviour, surface area and roughness changes and its level of success to meet the DOE requirements for BPPs. Especially, electrochemical stability was investigated in terms of corrosion measurements within a three electrode cell system. Active exposure area of 1 cm2 bipolar plate material was used as working electrode (WE). A platinum wire with an activated carbon felt, and reversible hydrogen electrode employed as a counter electrode (CE), and reference electrode (RE), respectively. Bipolar plates were subjected to chemical storage in 0.5 M H2SO4 at 80 ºC as a function of time. Further, electrochemical stability were evaluated in term of potentiostatic conditions such as open circuit potential (OCV), anodic and cathodic polarisation conditions. Finally, a corrosion analysis is presented using atomic force microscopy (AFM), confocal microscopy and/or µ-computed tomography (µ-CT) as well as inductively coupled plasma with mass spectrometry (ICP-MS) as an attempt to know the surface area changes of corrosion in metallic bipolar plates and their degradation products in acid.

Figure 1: Three-electrode set-up for corrosion measurements (left), AFM picture of metallic BPP (right)

Figure 1
Study on Carbon Corrosion Induced Crack Propagation on Cathode Catalyst Layer in Polymer Electrolyte Membrane Fuel Cell Under Startup-Shutdown Operating Condition
Authors: Li Yunqi , Chen Xiran , Xu Jun
Published: February 2020

Polymer electrolyte membrane fuel cell (PEMFC) has the advantages of high energy density, high efficiency and theoretically zero emission [1], and is expected to replace the traditional internal combustion engine [2] to solve the problems of severe environmental pollution and resource shortage. However, the wide-spread application of FC generators in vehicles faces two major bottlenecks, i.e. cost and durability. Complex vehicle operating conditions including speed change, startup and shutdown, idling and high power pose great challenges to PEMFC's durability. It is found that under the adverse operating conditions such as startup-shutdown, carbon corrosion induced crack propagation [3] in the cathode catalyst layer is an inevitable attenuation and aging behavior, which ultimately leads to fuel cell performance degradation and failure (Figure 1).

This study intends to use the combination of experimental research, numerical calculation and theoretical analysis. The formation of CO2 is quantified to characterize carbon corrosion rate. The kinetics of carbon corrosion is slow in normal operation. Therefore, the accelerated stress test conditions used in this work were adopted from Ref. [4]. The cell voltage was cycled from a lower potential of 0.6 V for 30 s, to an upper potential of 1.4 V for 60 s, to simulate the high potential during startup-shutdown conditions.

The crack propagation before and after degradation are observed and measured using an optical microscope. The existence and growth of cracks aggravate the carbon corrosion [5], destroy the continuity of catalyst layer, or cause local water flooding [6], which increase the mass transfer resistance and results in a significant performance degradation.

A multiple physical model is set up, that couples carbon corrosion, mechanical properties change and crack growth during the startup-shutdown cycling. The carbon corrosion model and CL agglomerate model are combined to predict performance of CL during startup-shutdown cycles. In addition, the model of stress corrosion crack is established to simulate the crack growth with the carbon corrosion and mechanical properties change. A parametric study was presented to analyze the effect of operation condition (e.g., relative humidity, pressure, maximum and minimum voltage) and structural parameters (e.g., carbon loading, porosity, and ionomer fraction) on the performance degradation and crack growth at various numbers of cycles.

With the wide application of fuel cell, the degradation of catalyst performance is inevitable. This study can fill the gap in the mechanism of crack growth caused by carbon corrosion, as well as provide critical guidance for PEMFC lifetime prediction.

Figure 1
In-Situ Diagnostics of Coupled Electrochemical-Mechanical Properties of Solid Electrolyte Interphases on Lithium Metal for Rechargeable Batteries
Authors: Xiao Xingcheng
Published: February 2020

Low cycle efficiency and dendrite growth are two critical barriers for rechargeable batteries using Li metal as negative electrodes, mainly due to the coupled mechanical/chemical degradation of the SEI layer formed on Li metal surface. We have developed a comprehensive set of in situ diagnostic techniques combined with atomic/continuum modeling schemes to investigate and understand the coupled mechanical/chemical degradation of the SEI layer/Li system including fundamentally understanding the surface and interface phenomena. We have found that the mechanical incompatibility between SEI and soft Li leads to the complicated mechanical behaviors of the lithium metal electrode during the plating and stripping process. We systematically investigated the relationship between surface morphology and current density distribution which results in an inhomogeneous Li plating/stripping process. Based on the fundamental understanding from the integrated in-situ diagnostics, atomic simulation, and continuum frame work, we have developed a new coating design strategy to achieve high cycle efficiency/dendrite free and extend the cycle life of lithium rechargeable batteries.
Proving the Viability of an Electrochemical Process for the Simultaneous Extraction of Oxygen and Production of Metal Alloys from Lunar Regolith
Authors: Symes Mark , Lomax Bethany , Conti Melchiorre , Khan Nader , Bennett Nick , Ganin Alexey
Published: February 2020

The development of an efficient process to simultaneously extract oxygen and metals from lunar regolith by way of in-situ resource utilisation (ISRU) has the potential to enable sustainable exploration beyond Earth. The Metalysis (FFC Cambridge) process can electrochemically reduce a wide range of metal oxides to produce metals and alloys for powdered metallurgy and additive manufacturing, with the co-generation of oxygen at the anode. In this talk, we will demonstrate proof-of-concept for the electro-deoxidation of powdered lunar regolith by a Metalysis-FFC approach to produce oxygen and metal alloys. The resulting metallic powder was found to contain only a very small percentage of oxygen (a portion of which was due to post electrolysis surface re-oxidation) and to consist primarily of Al/Fe(-Si), Fe/Si(-Ti/Al), and Ca/Si/Al(-Mg) alloys. The challenges and opportunities for the Metalysis-FFC process for lunar ISRU will be discussed in light of the results presented in this talk.
Electrolyte Science for Divalent Metal Batteries
Authors: Hahn Nathan T , Zavadil Kevin R
Published: February 2020

Multivalent cation-based electrochemical energy storage concepts provide great promise and great challenges as beyond Li-ion technologies. Such systems based on Mg2+, Zn2+, or Ca2+ cations challenge current understanding of solvation and resultant properties in non-aqueous electrolytes, where the doubly-charged cation introduces new liquid solvation behavior compared to the more established alkali-metal (Li+, Na+) systems. In this presentation, we drive toward a more unified framework for understanding of solvation phenomena through a systematic comparison of solvation structure and dynamics in organic divalent electrolytes. Connecting these solvation trends to critical ensemble electrolyte properties such as ion transport and electrochemical stability will be the focus of this work. Specifically, we will highlight lessons learned from ethereal solvent systems (cylic ethers and glymes), which are the solvents most commonly employed in beyond Li-ion chemistries at large. We will discuss how the competition between anion and solvent coordination with the divalent cation regulates the observed electrochemical behavior and connect these themes to the principles of electrolyte design.
Novel Cell and Manufacturing Architecture Enabling Next-Generation, High Energy Density Chemistries
Authors: Ota Naoki
Published: February 2020

The commercialization of high energy density systems has the potential to radically improve cost ($/kWh) and adoption in both the automotive and grid energy spaces. A hybrid cell concept in which separate electrolytes are used with the cathode and anode of a single cell allows the cathode electrolyte (catholyte) to be selected for oxidative stability with a high voltage cathode, and the anode electrolyte (anolyte) to be selected for reductive stability with a high capacity anode (e.g., silicon-carbon or Li metal). The combination enables cells of exceptional energy density while retaining stability and life heretofore only available at much lower cell voltages. This approach is ideally suited for use with semi-solid electrodes of 24M’s proprietary design, made by an innovative manufacturing process in which the electrolyte also serves the function of a processing solvent, being directly mixed with active materials and conductive additives prior to forming. Electrode drying, calendaring, and the use of binder are eliminated. Since the semi-solid cathode and anode are independently processed, a different electrolyte composition can be selected for each. 24M’s “unit cell” architecture, in which thick electrodes and high areal capacities are used to create high energy density cell products with reduced inactive materials content has the potential to revolutionize next-generation battery performance.

Figure 1
Molecular-Level Engineering of Protected Li Metal Anodes for High Performance Next-Generation Batteries
Authors: Adair Keegan , Zhao Yang , Sun Qian , Li Ruying , Sun Xueliang
Published: February 2020

Li metal is a promising anode material for next-generation Li-metal battery systems due to its ultra high theoretical capacity (3860 mAh g-1) and low electrochemical potential (-3.04 V vs. standard hydrogen electrode). However, the instability of Li metal towards liquids electrolytes, unstable solid electrolyte interphase (SEI) formation, and dendritic lithium have caused significant safety concerns that have inhibited its commercialization [1]. It is believed that artificial SEI layers formed through various techniques can stabilize the Li metal interface and enable stable electrochemical cycling with higher Coulombic efficiency. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are nanoscale coating techniques that are capable of controlling the interfacial chemistry down to the atomic level [2]. Herein, we demonstrate the effectiveness of these techniques in enabling high performance Li metal anodes for next-generation battery systems. Various polymeric protective coatings are synthesized on Li metal by MLD to enable prolonged lifetime and cycling stability. Metalcones including Alucone and Zircone are explored and shown to greatly enhance the performance of Li-S and Li-O2 systems [3]. Moreover, the ability to fine tune the composition of artificial SEI layers is exemplified by combining ALD/MLD techniques to form hybrid organic/inorganic protection layers to further improve the stability of the Li metal anode. The performance of the protected Li metal anodes are optimized in various electrolyte systems to achieve long life times at relatively high current densities in symmetrical cells and full cells. Furthermore, a better understanding of the role of these organic/inorganic polymeric films are gained through advanced ex-situ and in-situ characterization techniques, providing insight into the mechanism of improved performance. These works display the advantages of ALD/MLD for precise interfacial engineering at the atomic/molecular level towards achieving high performance next-generation batteries.

[1] Cheng, X.B.; Zhang, R.; Zhao, C.Z.; Zhang Q. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chem. Rev.,
2017, 117(15), 10403-10473.

[2] Meng, X.; Yang, X.Q.; Sun, X. Emerging applications of atomic layer deposition for lithium-ion battery studies. Adv. Mater., 2012, 24(27), 3589-3615.

[3] Zhao, Y.; Goncharova, L.V.; Sun, Q.; Li, X.; Lushington, A.; Wang, B.; Li, R.; Dai, F.; Cai, M.; Sun, X. Robust Metallic Lithium Anode Protection by the Molecular Layer Deposition Technique. Small Methods, 2018, 2(5), 1700417.
Starch Derived Hard Carbon Anodes for Sodium Ion Battery
Authors: Arie Arenst Andreas , Kristianto Hans , Muljana Henky
Published: February 2020

In this present work, hard carbons were synthesized from local Indonesian starch by using hydrothermal carbonization followed by the activation process at high temperature. It was found that as obtained hard carbons showed a sheet like morphology, a well-connected structure and a large interlayer spacing. The hard carbons were then utilized as anode materials for sodium ion battery. The electrochemical characterizations were examined by cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy. The best hard carbon sample performed a stable cycle profiles, maintaining a high specific capacity of around 180 mAh g-1 until the 100th cycle at a current density of 100 mAg-1 These very good performances were ascribed to the large interspacing of hard carbons, carbon defect structure and sheet like morphology which can provide a large space for sodium storage and facilitate sodium ion transfer.
The Influence of Ionomeric Coatings at the Electrolyte-Electrode Interface in Metal Batteries
Authors: Merrill Laura C. , Ford Hunter O. , Schaefer Jennifer L.
Published: February 2020

The increased use of electronic devices and electric vehicles over the past decade has led to the development of advanced lithium-ion batteries. However, the intercalation electrode materials used in lithium-ion batteries have inherently low theoretical capacities. The use of metallic anodes provides a pathway to increased energy density. Metallic electrodes suffer from instabilities at the electrode-electrolyte interface, including unstable SEI formation, low coulombic efficiencies, and dendritic growth. This work studies the use of thin film ionomers as a protection layer between the electrolyte and the anode for lithium metal and magnesium metal batteries. The ionomer in use is a crosslinked polymer network with covalently bound anions that is coated onto a traditional microporous separator. We quantify the impact of the ionomer on cation transference number and on coulombic efficiency, overpotential, and cell lifetime while galvanostatic cycling. Post-mortem analysis is completed to evaluate dendrite formation and electrolyte decomposition. We find that the thin ionomeric coatings can influence the metal deposit morphology and that the composition of the coating influences the effectiveness as a protection layer.
Microstructured Electrodes Supported on Serpentines for Stretchable Microbatteries
Authors: Djenizian Thierry
Published: February 2020

Energy storage microsystems composed of thin-film devices (supercapacitors and batteries) have attracted attention to ensure autonomy of complex devices for wearable microelectronics. Recently, flexible systems have been investigated as deformation and integration of rigid micropower sources cannot be achieved.1-5 The technological challenge is to design energy storage devices showing high electrochemical performance with advanced mechanical properties to prevent crack issues during electrochemical and mechanical tests. But in simple flexible micropower sources, the strains experienced by the active materials during bending usually remain well below the typical levels required leading to multiple fractures and subsequent loss of electrical contact.

In this work, the fabrication of LNMO micropillars supported on Al serpentine interconnects has been achieved by laser patterning technique. Morphological and chemical characterizations confirm the formation of independent micropillars while preserving the underlying Al film. We show that unlike compact and continuous electrode thin-films, vertical micropillar structures supported on serpentines can be stretched up to 70% without structural damaging owing to the presence of empty spaces that can prevent the formation of cracks and the electrode delamination. The present approach based on the fabrication of microstructured electrodes supported on serpentine interconnects can be extended to a wide range of materials, which opens promising perspectives for the conception of truly stretchable devices such as stretchable micro-batteries.6

References

Y. Zhang, Y. Zhao, J. Ren, W. Weng , and H. Peng, Advances in Wearable Fiber-Shaped Lithium-Ion Batteries, Adv. Mater., 28, 4524 (2016).

S. Pan, J. Ren, X. Fang, and H. Peng, Integration: An Effective Strategy to Develop Multifunctional Energy Storage Devices, Adv. Energy Mater., 6, 1501867 (2016).

C. Yan and P. S. Lee, Energy Storage and Conversion Devices, Small, 10, 3443 (2014).

K. Jost, G. Dion, and Y. Gogotsi, Textile Energy Storage in Perspective, J. Mat. Chem. A, 2, 10776 (2014).

K.Y. Xie and B. Q. Wei, Materials and Structures for Stretchable Energy Storage and Conversion Devices, Adv. Mater., 26, 3592 (2014).

M. Nasreldin, R. Delattre, B. Marchiori, M. Ramuz, S. Maria, J. L. de Bougrenet de la Tocnaye, Microstructured electrodes supported on serpentine interconnects for stretchable electronics, APL Mat., 7, 031507 (2019).

Figure 1. Morphological and chemical characterizations of stretchable electrodes fabricated onto PDMS. (a) Tilted and (b) cross-sectional SEM images of LNMO micropillars supported on Al serpentines. (c) EDS chemical mapping of a region carrying 14 micropillars.

Figure 1
A Three-Dimensional, Interconnected Composite As a Thin Film Solid Electrolyte
Authors: Palmer Max Jared , Chen Xi Chelsea , Kalnaus Sergiy , Westover Andrew S , Dudney Nancy J.
Published: February 2020

Lithium metal batteries have the potential to enhance the energy and power density of commercial rechargeable batteries. A lithium metal anode may increase the energy density by 30% relative to current lithium-ion battery technologies. The promise of these improvements hinges on a successful solid electrolyte that is thin (< 30 μm).

Inorganic ceramic electrolytes can offer reasonable ionic conductivities but are typically bottlenecked by intensive processing. Solid polymer electrolytes offer the advantages of flexibility, low-cost processing, and a greater adhesion to the electrodes than a ceramic. The biggest drawback to solid polymer electrolytes is their low ionic conductivity. A composite electrolyte consisting of a hard ceramic phase and a processible polymer phase aims to utilize the advantages of each as a solution for solid-state electrolytes.

Here we introduce an approach to fabricate a solid composite electrolyte film that is thin, highly ionically conductive, and mechanically robust with good manufacturability. Without the use of plasticizers, our composite film has an ionic conductivity of approximately 1.0 × 10-4 S/cm at 30°C with an activation energy of ca. 0.44 eV. The high conductivity was achieved by creating a 3D, interconnected structure of the ceramic with greatly reduced interparticle resistance. Ion conduction path in the composite electrolyte is investigated by finite element analysis.

Acknowledgements: This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE), under contract DE-AC05-00OR22725, was primarily sponsored by the Office of Energy Efficiency and Renewable Energy for the Vehicle Technologies Office’s Advanced Battery Materials Research program and partially sponsored by the Laboratory Directed Research and Development Program (LDRD) of ORNL.
Predicting Polymer Flammability Using Machine Learning Methods
Authors: Shelton Madeline , Venkatram Shruti , Ramprasad Rampi
Published: February 2020

Solid state batteries are a promising replacement for traditional liquid electrolyte batteries due to their superior stability and inflammability. Conventional lithium ion batteries use an organic liquid electrolyte, which is a potential hazard when it undergoes a decomposition reaction leading to an explosion. A solid, non- flammable electrolyte is a promising alternative. However, the chemical space of polymers is diverse and identifying new materials for electrolytes requires a critical screening criterion. Polymer flammability can be quantified using the limiting oxygen index (LOI), which is the minimum oxygen concentration necessary to sustain stable combustion. Polymers with an LOI greater than 21 are inflammable at room temperature and can be deemed safe for use in a battery. In this work, we predict the LOI for new polymers using a combination of data driven and machine learning methods. We have carefully curated a dataset of polymers and their associated LOI values, which are experimentally determined. A fingerprinting scheme is used to numerically represent the polymers from an atomistic to morphological length scale. We then use a gaussian progress regression model to map the polymers from their fingerprint space to their LOI. This model can then be used to rapidly predict the LOI of a polymer and its associated uncertainties. This study could rationally guide the design of solid polymer electrolytes which are thermally stable and inflammable.
(Invited) Dry Process for the Preparation of Porous Composite Electrodes for Battery Application
Authors: El-Khakani Soumia , Verdier Nina , Lepage David , Rynne Olivier , Zohrevand Ahmad , Ciszewski Dorian , Badia Antonella , Rochefort Dominic , Dollé Mickael
Published: February 2020

The development of advanced Li-ion battery would require innovative approaches to improve the present performances, while lowering the environmental footprint and price of their fabrication. In this scope, we are currently carrying out different projects to consider the electrode materials as well the process to make the batteries. This presentation will focus on the second aspects, which concerns the development of a solvent-free process to make composite electrodes using an owned patented process by Hutchinson [1]. Currently, most of the electrode fabrication involves the use of organic solvent (typically N-methyl-2-pyrrolidone, NMP, which is toxic). Life cycle analysis studies of the LiB manufacturing process showed that this type of electrode preparation accounts for a significant portion of their overall environmental imprint [2]. While the use of water, instead of NMP, would be preferable to minimize this impact [3], a solvent-free electrode manufacturing consumes less energy in comparison to solvent-based methods [4].

Different electrode formulations were prepared by the dry process. The mechanical, electrical and electrochemical properties in half cells were assessed and compared to composite electrodes obtained by doctor blade coating using the classical PVdF binder. The different steps of the dry process (mixing, lamination and adhesion to current collectors) were studied and optimized separately to reach the maximum loading, while ensuring good power performances. The Ragone plots for each electrode, tested in half cells, were evaluated and the best formulation was retained for the full cell manufacture. The performances of LiFePO4/Li4Ti5O12 batteries are comparable to our best electrodes made with PVdF. The different aspects of the process will be discussed in this presentation.

References

[1] Ph. Sonntag, D. Aymé-Perrot, B. Dufour, Arnaud Prébé, N. Garois, Patent WO2015124835A1

[2] G. Majeau-Bettez, T.R. Hawkins, A.H. Stromman, Environmental Science & Technology, 2011, 45, 4548.

[3] M. Zackrisson, L. Avellan, J. Orlenius, Journal of Cleaner Production, 2010, 18, 1519.

[4] Environmental Protection Agency “Lithium-ion batteries and nanotechnology for electric vehicles: A life cycle assessment,” EPA 744-R-12-001, 2012.
Detrimental Effects of Chemical Cross-Talk in Rechargeable Lithium Metal Batteries
Authors: Lee Hongkyung , Lim Hyung-Seok , Ren Xiaodi , Engelhard Mark H , Han Kee Sung , Xiao Jie , Liu Jun , Xu Wu , Zhang Ji-Guang
Published: February 2020

The energy density of conventional Li-ion batteries (LIBs) has eventually reached their theoretical limit. Increasing worldwide efforts have been made towards the next generation of energy storage systems including batteries using Li metal anode in combination with various cathodes, including intercalation compounds (such as NMC) or conversion materials (such as oxygen (O2) and sulfur (S)). For a full demonstration of new battery chemistries, the interfacial stability is essential to long cycle lifespan and battery performance. In general, batteries suffer from “cross-talk” processes upon cycling by the crossover of parasitic chemicals through the electrolyte media [1]. Indeed, "cross-talk" phenomena in Li-ion batteries, such as Mn2+ crossover from the cathode and contaminate graphite anode has been well established [2]. Li-S and Li-O2 batteries also have the shuttle issues of soluble redox-active materials, polysulfides and superoxide radical anions, respectively. However, the similar characteristics in Li metal batteries (LMBs) with conventional Li ion intercalation cathodes have rarely been studied. Therefore, an in-depth understanding of how a Li metal anode affects the cathode interface chemistry is critical to ensure the long-term cycling stability of LMBs.

Here, we report the cathode failure triggered by the chemical “cross-talk” between the electrode pair in rechargeable LMBs. In sharp contrast to LIBs, the cathode in LMBs suffers more significant and irreversible capacity fade during cycling, and its capacity cannot be fully recovered in spite of repeated replacement with new Li metal in the successive cycling. In-depth characterizations of the cathode surface reveal severe deterioration of cathode electrolyte interphase related to the significant accumulation of highly resistive polymeric components and lithium fluoride. Extensive salt-anion decomposition at Li metal surface can cause the chemical aging of the electrolyte allowing the migration of soluble byproducts toward the cathode side, resulting in the severe deterioration of cathode and separator surfaces. A selective Li-ion permeable separator with polydopamine coating has been developed to mitigate the detrimental chemical crossover and enhance the cathode stability.

[1] Mikhaylik, Y. V.; Akridge, J. R., Polysulfide Shuttle Study in the Li/S Battery System. J. Electrochem. Soc.
2004,
151 (11), A1969-A1976

[2] Vetter, J.; Novák, P.; Wagner, M. R.; Veit, C.; Möller, K. C.; Besenhard, J. O.; Winter, M.; Wohlfahrt-Mehrens, M.; Vogler, C.; Hammouche, A. Ageing mechanisms in lithium-ion batteries. J. Power Sources
2005,
147 (1), 269-281.

Figure 1
Electric Vehicle Battery Degradation Under Electric Grid Operations: Vehicle to Grid Strategies
Authors: Dubarry Matthieu , Baure George
Published: February 2020

Battery degradation is extremely sensitive to usage and chemistry. Some batteries may be markedly sensitive to temperature, to state of charge, to both, or to some other factors. This raises concerns over battery durability in the rollout of electric vehicles (EVs) in hot climate. Additionally, with the integration of more and more intermittent renewable energy power plants on the grid, there is a push to use EV batteries as energy storage systems which may stress the batteries even more. In most studies on the techno-economical impact of EVs on the grid, the battery is often viewed as a black box and therefore there is no consensus on the actual long term impact of climate and/or vehicle-to-grid (V2G) and grid-to-vehicle (G2V) charging profiles on batteries. This work aims at assessing such impact.

Daily vehicle usage can be broken down into driving, charging and idling periods. In most cases, car batteries spend most of their time idling and it is therefore essential to understand the degradation associated with time, temperature and state of charge. Specifically, we studied the impact of driving on the cell degradation with or without V2G and G2V episodes. We also investigated the impact of frequency response at different intensities. All the data was analyzed using HNEI’s unique diagnosis and prognosis tools to forecast the degradation over the battery warranty period and beyond.
Molecular Dynamics Simulations of Ion Transport in Poly-Ethylene Oxide
Authors: Maheshwari Shantanu , Thakkar Foram , Balachandran Janakiraman , Sanyal Suchismita , Balsara Nitash P
Published: February 2020

Solid polymers are becoming a promising alternative option as an electrolyte material in lithium ion batteries [1,2,3]. Solid polymer electrolytes have certain advantages over traditional electrolytes – non-flammability, good electrochemical and mechanical stability, and ability to hinder the growth of dendrites at electrode surfaces [4,5]. Poly-ethylene oxide (PEO) is one such polymer which has been considered a viable option due to its ability to solvate lithium ions and its relatively high ion conductivities. However, the bulk Li-ion conductivities even in PEO at room temperature are at least an order of magnitude less than the traditional liquid electrolytes [2,6].

In this study, we explore the influence of ion concentration and pressure on the Li-ion transport mechanism and in turn on its conductivity in PEO by performing molecular dynamics (MD) simulations of a lithium salt (lithium bis(trifluoromethane) sulfonamide (LiTFSI)) in polymer matrix of poly-ethylene oxide (PEO). We explored the influence of pressure to examine if it has any role in increasing the performance of PEO as an electrolyte. We computed parameters like diffusivity, conductivity and transference numbers that are crucial in determining the performance of PEO as a potential electrolyte for lithium ion batteries. We observe that diffusivity and conductivity decrease with increase in pressure while transference number remain almost independent. The simulation framework can be further used to explore polymers other than PEO as an electrolyte material or to test different block copolymers based on PEO.

[1] F. M. Gray. Solid polymer electrolytes: fundamentals and technological applications (pp. 83-93). New York: VCH (1991).

[2] D. T. Hallinan Jr., & N. P. Balsara. Polymer electrolytes. Annual review of materials research, 43, 503-525 (2013).

[3] S. Mogurampelly, O. Borodin, & V. Ganesan. Computer simulations of ion transport in polymer electrolyte membranes. Annual review of chemical and biomolecular engineering, 7, 349-371 (2016).

[4] F. M. Gray. Polymer electrolytes. Royal Society of Chemistry (1997).

[5] K. J. Harry, D. T. Hallinan, D. Y. Parkinson, A. A. MacDowell, & N. P. Balsara. Detection of subsurface structures underneath dendrites formed on cycled lithium metal electrodes. Nature materials, 13(1), 69.4 (2014).

[6] A. A. Teran, M. H. Tang, S. A. Mullin, & N. P. Balsara. Effect of molecular weight on conductivity of polymer electrolytes. Solid State Ionics, 203(1), 18-21 (2011).

Figure 1
(Invited) Static and Dynamics View of the Solid Electrolyte Interphase during Charge Transfer Reactions -Modeling and Experiments
Authors: Qi Yue , Liu Zhe , Li Yunsong , Liu Jialin , Zhang Qinglin , Lu Peng , Xiao Xingcheng , Chen Long-Qing
Published: February 2020

By treating the solid electrolyte interphase as a model layer, the energy landscape of the simplest charge transfer reaction of Li+ + e- --> Li0 was predicted via a new Li/Li2CO3/liquid-EC interface model with density functional theory calculations. The model revealed that if the SEI layer is a perfect crystal, the charge transfer step will occur underneath the SEI layer.

However, it takes time for the SEI to build up into a nanometer-thick layer from the molecular level reduction reactions on negative electrodes. Isotope-assisted time-of-flight secondary ion mass spectrometry analyses revealed a new “bottom-up” SEI growth mechanism. It was discovered that the topmost SEI near the electrolyte formed first and the SEI near the electrode formed later.

The formation rate of the surface SEI layer can be intertwined with the Li morphology change, which imposes a deformation rate on the surface layer. Even for Li-metal in the trace amount of oxidizing gas (O2), the Li morphology was switched from spheres to wires and to spheres again by the oxygen partial pressure, which corresponds to different oxidation rates. There is a fine balance between the ion current density and a growth rate of a thin lithium-oxide shell on the surface of the metallic Li.

While capturing the time evolution of the SEI layer is still very challenging for modeling, the Li-morphology evolution was captured via a multiscale model. This model connected the atomic level charge-transfer physics with the mesoscale morphological evolution based on the phase-field method and transition state theory. It successfully captured the morphological evolution difference between dendritic Li plating and faceted Mg plating and clarified the most efficient method to achieve a smooth plating surface is lowering the exchange current in the charge transfer reactions.