Abstracts

As an essential part of understanding the contribution that computational
science will make to accelerating progress toward scalable electrochemical
energy storage systems, you are encouraged to submit poster abstracts for
inclusion within a poster session of our Symposium on Beyond Lithium Ion:
Computational Perspectives.

The program committee for this symposium will review abstracts for quality
and responsiveness to the symposium purpose and theme.  The intent is to
provide an appropriate venue for sharing research results, approaches, and
ideas with those researchers working in the field or with interest in
beginning work in scalable electrochemical energy storage.

Posters should be no larger than 4′ x 4′ and will be displayed on freestanding bulletin boards.  Push pins will be available.  Posters may be put up between 3 and 4:30p.m on Monday, May 3, 2010.

(Abstracts ordered below as submitted)

Abstracts PDF

Energy Storage Beyond Lithium Ion: Computational Perspective

May 3, 2010 Poster Session Abstracts

Larry Yount

LaunchPoint Technologies

Lyount@launchpnt.com

The Need for Ultra Hi-reliability BMS Design

Large-pack Li-ion BMS design is an emerging field and the essential system issues are known by only a few engineers. As a result, the required technology to ensure adequate safety and reliability is often missing from BMS designs, thus risking unnecessary failures leading to warranty repairs, unacceptable life-cycle costs, and poor market acceptance. Large Li-ion battery packs for PHEVs, HEVs, and pure EVs (P/H/EVs) are complex, precision systems that must function with high reliability and safety over a wide range of environmental and operational conditions. LaunchPoint has created BMS system designs that meet these challenges by applying ultra Hi-Rel system architecture and techniques forged in our experience with commercial aviation Fly-By-Wire control systems (the headwaters for ultra Hi-Rel design), as well as our proprietary P/H/EV pack design concepts.

BMS electronics are often assumed to be much more reliable than the cells, however, recent studies indicate this is not true for large, complex packs. Also, attention is often focused on the cells because they cost 10X more than the BMS, yet BMS failures can result in pack-level repairs.  This coupling of BMS failures to costly maintenance actions drives BMS life-cycle-costs to clearly unacceptable levels (approaching 3X the BMS purchase cost, or >$2000), while damaging market acceptance.

Lynn Trahey

Argonne National Laboratory

trahey@anl.gov

Electrocatalysts for Li-Air Batteries

The concept of using lithium-metal oxides with a high Li2O content, such as Li5FeO4 (5Li2O•Fe2O3), as electrocatalysts for lithium-oxygen cells has been explored.  At least four lithium ions, corresponding to two Li2O units per Fe atom can be extracted from Li5FeO4 between 3.5 and 4.0 V.  If initially discharged, the redox behavior of Li/Li5FeO4-O2 cells is similar to Li/O2 cells, delivering approximately 2500 mA/g carbon on the first discharge at ~2.6 V with a large polarization during the subsequent charge above 4 V.  By contrast, if initially charged, a significant amount of Li2O can be extracted from the defect antifluorite Li5FeO4 structure below 4 V; when subsequently discharged in the presence of oxygen, 900 mAh/g carbon can be recovered from the electrocatalyst between 3.2 and 2.8 V before the conventional onset of Li2O2/Li2O formation at 2.6 V.  Acid-treated Li2MnO3•LiFeO2 electrocatalysts (i.e. {Li2O•MnO2}•{Li2O•Fe2O3}) provide close to 5000 mAh/g carbon for the early cycles, which translates to a capacity of approximately 700 mAh/g of electrocatalyst + carbon.  The data have implications for designing electrocatalyst materials for reversible Li/O2 cells that actively participate in Li2O extraction and reformation reactions during charge and discharge.

Wayne Miller

Lawrence Livermore National Laboratory

miller99@llnl.gov

Computational and Practical Aspects of Battery Technology at LLNL

LLNL has a significant history of computational and practical work in energy storage and battery technology that will be presented.  Computational efforts range from molecular dynamics studies of novel materials and chemistry to sophisticated multi-physics continuum models.  Computational resources at LLNL are at the PetaFLOP scale and include the IBM BlueGene/L system.  Practical efforts include significant forensic and laboratory work for federal and industrial customers, primarily on Li-Ion systems.  Notably LLNL developed a 1.5MW Li-Ion battery system to power a solid state laser, and also participated in the first commercial manufacture of polymer gel Li-Ion batteries.  Several new efforts are underway, including the development of a fully coupled high resolution multi-physics battery simulation capability and a novel sodium-beta battery chemistry for vehicle and utility scale applications.

Zhengcheng Zhang

Argonne National Laboratory

zzhang@anl.gov

Silane Based Electrolyte for Lithium Ion Battery Application

With the increasing demands for rechargeable lithium ion batteries in applications such as consumer electronics, electric- and hybrid-electric vehicles, and implantable medical devices, there are growing concerns about the safety limitations of conventional electrolytes. Attempts have been made to improve the thermal stability and safety characteristics of the electrolytes by developing stable and safer solvents with less flammability and toxicity.

Si-based electrolyte solvents can easily dissolve most lithium salts including LiBOB, LiPF6, LiBF4, and LiTFSI. Cyclic voltammetry analyses show that silane-based electrolytes with a 0.8 M LiBOB salt are stable up to 4.7 V (Li/Li+); they also exhibit high lithium-ion conductivities of 1.29×10-3 S/cm at room temperature. Full cell performance tests with LiNi0.08Co0.15Al0.05O2 as the positive electrode and MCMB graphite as the negative electrode have shown excellent cyclability both at room temperature and at 40°C. As a new electrolyte for high voltage cathode materials, sufone-based electrolytes are developed for high energy lithium ion batteries. Their cell performance will also be presented in this poster.

Gi-Heon Kim

National Renewable Energy Laboratory

gi-heon.kim@nrel.gov

An Integrated Multi-Scale Multi-Dimensional Battery Model

Physics in battery system, such as kinetics, phase transition, ion transport, electronic current distribution, energy dissipation and heat transport happen over a wide range of time and length scales and closely interact. Therefore, multi-physics behaviors of batteries for next generation electric energy storage must be addressed over various length and time scales in which physical and chemical processes are occurring; from atomic variations to system interface controls. There have been various model-based investigations focusing on varied scales of battery physics to promote theoretical understanding beyond what is possible from experiment alone. NREL researchers have pursued to develop a model that incorporates physics in all scales with bridging of the existing varied scale models or by direct integration of them. An integrated multi-scale model would expand knowledge on interplay of different scale battery physics and show a pathway toward expediting the processs of advanced battery system developments enabling green mobility technologies.

This poster presentation will discuss existing model approaches, and introduce the recent progress and study with NREL’s multi-scale multi-dimensional (MSMD) model.

Gabriel Veith

Oak Ridge National Laboratory

veithgm@ornl.gov

Electrochemical characterization of metal air electrocatalysts

This presentation will detail the synthesis and characterization studies we have performed investigating the structure-property relationships associated with metal-air electrocatalysts.  Specific emphasis will focus on understanding structure-reactivity relationships.

Acknowledgements:

Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.

Rees Rankin

Center for Nanoscale Materials, Argonne National Laboratory

rrankin@anl.gov

DFT Based Insights into Potential Dependant Energetics of LixOy Species Formation on Transition Metal Surfaces

We present results from our initial DFT investigations into the relative energetics of LixOy species formation on low-index FCC(111) transition metal surfaces via multiple reaction mechanisms.  Results are augmented with analysis to account for potential dependence in activity and selectivity.  Comparisons to the reactivity and selectivity of the same transition metal catalyst surfaces for other oxide/peroxide products are made where possible.  Finally, we discuss the possibility of deriving linear scaling relations for intermediates and products in this reaction network.

Huiming Wu

Argonne National Laboratory

wuhm@anl.gov

Surface modification of LiNi0.5Mn1.5O4 by ZrO2 for lithium ion batteries

Recently, LiNi0.5Mn1.5O4 receives much attention as one of the most promising cathode materials for lithium-ion batteries due to its low cost, and low toxicity. Compared with the spinel LiMn2O4, LiNi0.5Mn1.5O4 exhibits higher working potential (4.7 V), which leads to higher specific energy density. However, under such high voltage, the electrolyte in the cell could easily be oxidized. One possible way of overcoming this potential issue is a surface modification or coating the LiNi0.5Mn1.5O4 with a very stable material that can act as barrier against electrolyte reactivity with the charged electrode at the electrode interface.  In this paper, we present a new process of coating LiNi0.5Mn1.5O4 with ZrO2 nano particles. The effect of coating on the cycle and calendar life as well as safety characteristic of the cathode will be discussed.

Maria Chan

ANL – CNM

mchan@anl.gov

First principles studies of Si anode surfaces

In lithium ion batteries, silicon is a promising alternative to carbon as an anode material due to enhanced safety and higher capacities. Unlike carbon, lithiation in silicon is accompanied by drastic phase, structural and volume changes, the understanding of which is crucial for improvement of capacity retention and battery performance. We present results of first principles calculations of lithium adsorption and absorption onto and into silicon surfaces, which simulate the initial stages of lithiation in silicon.  The thermodynamics, mechanics and kinetics of such ad/bsorption, and the effects of surface orientations, passivation and reconstructions, will be presented.

Zonghai Chen

Argonne National Laboratory

zonghai.chen@anl.gov

In situ High Energy X-ray Diffraction for Advanced Material Discovery and Design

It has been wildly accepted that the structure, chemical and physical defects of materials are critical factors to determine the performance of devices using such materials.  A comprehensive understanding of structure-property relationship of materials can provide valuable insight for the discovery and rational design of advanced materials with improved performance. The accomplishment of this challenging task will need critic support from state-of-the-art characterization techniques such as in situ high energy X-ray diffraction.

For instance, LiFePO4 was first reported by Goodenough and coworkers as a potential positive electrode material for lithium ion batteries in 1997. Because of its low electronic conductivity, the full potential of LiFePO4 for lithium ion batteries was not unlocked until Chiang and coworkers reported that high rate application of LiFePO4 can be achieved by chemical doping of metal metals supervalent to Li in nano-structured LiFePO4. However, the mechanism of the performance improvement is still under debating.

In this work, in situ high energy X-ray diffraction technique was used to investigate the phase formation and defect evolution of LifePO4 during solid state synthesis. The in situ experiment showed that LiFePO4 phase started to form at a temperature as low as 200oC, and a pure LiFePO4 was obtained at about 300oC. It was also found that impurity phases, which were identified as a mixture of Fe2P and Fe3P, started to appear when the LiFePO4 sample was baked at a temperature above 400oC. Electrochemical data showed that LiFePO4 synthesized at <400oC exhibit poor electrochemical activity while those samples prepared at >500oC have great performance. With the combination of in situ data and electrochemical data, we realized that the Fe2P/Fe3P impurity phases are critical for the performance improvement.

Kah Chun Lau

Argonne National Laboratory

kclau@anl.gov

Thermodynamic Stability of Lithium Oxide and Lithium Peroxide

Li-air battery is one of the promising candidate for future energy storage beyond lithium ion battery. Its rechargeable performance however is limited by its cathode kinetics, i.e. the formation and decomposition of lithium oxide/peroxide in the cell. To elucidate the nature of this problem, a thermodynamic study of lithium oxide/peroxide is required. As a first step towards this goal, the bulks and the nanoparticles of these system have been investigated by density functional theory and classical molecular dynamics. By taking into account the effect of the temperature and size dimension of the system, the thermodynamic stability of lithium oxide/peroxide can be obtained.

Rajeev Surendran Assary

Material Science Division, Argonne National laboratory

assary@anl.gov

Designing Silicon based electrolytes: A Computational Approach

Rajeev S. Assary1, Larry A. Curtiss1, Zhengcheng Zhang2, Khalil Amine2

1Materials Science Division, Argonne National Laboratory, Argonne, IL 60439

2 Electrochemical Technology Program, Chemical Sciences and Engineering Division Argonne National Laboratory, Argonne, IL 60439

Recently, silicon containing electrolytes received huge interest in the energy storage devices such as lithium batteries and super capacitors due to their nontoxic, nonflammable, and biocompatible nature. Additionally, it has been reported that, polysiloxanes containing oligo (ethylene oxide) groups have ideal properties for battery electrolytes such as, low glass transition temperatures, effective ionic transport, low viscosity and excellent conductivity in the presence of lithium ions. We have employed density functional theory (DFT) to understand the important properties of these electrolytes such as thermodynamic stability, oxidation potentials, and reduction potentials. The relative thermodynamic stability of silicon based electrolytes over the carbon-based electrolytes and detailed fragmentation patterns for various siloxanes will be presented. The effect of functional groups in tuning the oxidation potentials, new designs for electrolytes and computed oxidation and reduction potentials have also been studied and will be presented. Our research will provide significant insights to understand the properties of siloxane electrolyte materials at an atomic scale and these studies are a key to design efficient and improved electrolytes for battery applications.

Yan Qin

Argonne National Laboratory

qin@anl.gov

Surface chemistry in Lithium ion battery

It has been well known that the surface property plays an important role in determining the performance of the material. In lithium batteries, the surface property of the electrode materials has large impact on the cell cycling performance and safety.  A good surface will facilitate lithium and lithium ion transportation and also suppress the side reactions including the solvent decomposition. Tuning surface properties can be achieved by adding additives in the electrolyte to modify the SEI (solid electrolyte interface) layer or the surface functional groups. Quite a few additives with oxalato groups have been proved to have significant improvement on cell capacity retention and thermal stability. To gain more control on the modification of the surface property, direct surface coating techniques, such as sol-gel and atomic layer deposition, are employed to coat the surface with carefully selected desirable layer to achieved better performance and better protection.

Understanding of the relationship of surface chemistry and performance of materials can provide valuable insight for the design of appropriate material surface with improved performance.

Partha Mukherjee

Oak Ridge National Laboratory

mukherjeepp@ornl.gov

How Can Detailed Modeling in Fuel Cells Be Adapted to Li/Air Batteries?

Partha P. Mukherjee, Sreekanth Pannala, John A. Turner;Computational Engineering & Energy Sciences Group:Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

Recently, Li/air batteries have received much attention due to the high theoretical specific energy [1,2]. Unlike conventional lithium ion batteries, Li/air batteries are operated in an ambient environment with air as the cathode material, which is absorbed during discharge. A salient performance limiting mechanism in Li/air batteries, with nonaqueous electrolyte, is the formation and precipitation of insoluble reaction products (i.e. Li2O and Li2O2) in the porous air cathode [3,4]. This results in blockage of the pathways for oxygen transport and concurrent reduction in the active reaction sites, which contribute significantly to the reduced discharge rate in Li/air batteries as compared to Li/ion batteries. Optimal design of the air cathode microstructure in Li/air batteries could potentially alleviate performance limitations due to deposition of the reaction products [5,6].

Similar scenario prevails in the polymer electrolyte fuel cell (PEFC), which has also emerged as a promising electrochemical energy conversion device for various applications in recent years. A key performance limitation in the PEFC comes from the inherent transport limitations in the porous electrode and fibrous diffusion media, on the cathode side, due to the underlying competing transport mechanisms (e.g. oxygen, proton) and the formation of liquid water as the H2/O2 electrochemical reaction product. Liquid water blocks the porous pathways for oxygen transport and covers the electrochemically active sites, thereby drastically reducing the cell performance. Recent efforts in direct simulation of electrochemistry coupled species, charge and two-phase transport in PEFCs [7-10] have focused on understanding the intricate structure-transport-performance interplay leading toward optimized electrode and diffusion media microstructures for enhanced performance.

Here, we draw analogies between the transport limiting scenarios prevalent in the Li/air and PEFC cathodes and suggest potential adaptation of the available, detailed computational modeling of microstructure coupled multi-physical mechanisms in the PEFC to Li/air battery air cathode design and optimization.

Claus Daniel

Oak Ridge National Laboratory

danielc@ornl.gov

In-situ Acoustic Emission Spectroscopy Combined with Stress Analysis – A New Way Towards Safe, Reliable High Energy Electrode Materials

K. Rhodes, S. Kalnaus, C. Daniel, N. Dudney, E. Lara-Curzio

In-situ acoustic emission spectroscopy is an effective method to detect, analyze, and understand mechanical events, cracking, and fracturing inside materials. It has been demonstrated to be a powerful tool to understand mechanical deformation and degradation in structural materials and composites and is in standard use in that field since decades.

New developments in information technology, analysis of large amounts of data, and data mining allow this method to be extended to electrochemical energy storage materials to understand mechanisms hidden inside the device. We envision this technique to be developed to become a standard tool for developing transformational active electrode materials as well as a state of health indication method.

New developments in modeling and simulation can guide the experiments and allow for thorough understanding of mechanical behavior and degradation mechanisms in those devices. We have chosen silicon anode material in order to investigate the possibilities and limitations of the technique.

*This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Vehicle Technologies Program for the Office of Energy Efficiency and Renewable Energy. Parts of this research were performed at the High Temperature Materials Laboratory, a National User Facility sponsored by the same office and at the Shared Research Equipment Collaborative Research Center sponsored by the Office of Science, Basic Energy Sciences Program.

Bob Guimarin

Electric Vehicle Infrastructure Network, Inc.

bob@beyond-the-plugin.com

Portable Energy Solutions

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Hakim Iddir

Argonne National Laboratory

iddir@anl.gov

Density functional theory studies of growth and properties of Li2CO3 on a graphite surface

Lithium-ion batteries have become widely used in various portable electronic devices and are also considered as the most promising power source for plug-in hybrid electric vehicles. However, their use has not yet reached its apogee, primarily owing to their stability and safety problems. One of the possible ways to improve upon the stability and safety performance of lithium-ion batteries without negatively affecting the physical properties of the electrolyte is through addition of additives in small quantities that will enhance the desired properties of the electrolyte, such as solid-electrolyte interphase (SEI) formation, cell voltage, and stability.

Li2CO3 is one the components of the SEI. It was shown to play a protective role for the anode, by limiting the diffusion of large molecules that trigger the exfoliation process, and hence the anode degradation. However, beyond a certain thickness this film reduces the mobility and the diffusion of Li-ion across. To improve the stability and overall performance of lithium-ion batteries, a detailed study of the SEI formation, structure and properties is necessary.

First-principles studies of Li2CO3 growth on graphite as well as of Li+ ion diffusion in bulk monoclinic lithium carbonate Li2CO3 crystal are performed to identify the stable structures of increasing number of Li2CO3 monomers, Li+ interstitial positions, its diffusion mechanism and migration barriers. The migration barrier for Li+ diffusion between the planes defined by Li2CO3 units along the open channels [010] is found to be small 0.34 eV, while a higher migration barrier (0.60 eV) was found for the diffusion across the planes. These results show that diffusion of Li+ in Li2CO3 is favored along [010] and not a limiting factor for Li+ ion transport, in Li-ion batteries with suitably oriented protective solid electrolyte interphase layer.