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V.F Energy Frontier Research Centers V.F.1 Energy Frontier Research Center at ANL (ANL) Michael Thackeray Argonne National Laboratory 9700 South Cass Avenue Argonne, IL 60439 Phone : (630) 252-9184 ; Fax : (630) 252-4176 E-mail: thackeray@anl.gov Collaborators: ANL: S.-H. Kang, J. R. Croy, M. Balasubramanian (APS) LBNL: V. Battaglia Start Date: October 1, 2010 Projected End Date: September 30, 2011 Objectives · Conduct surface studies of electrode materials relevant to the BATT program to complement the research being conducted by the EFRC, Center for Electrical Energy Storage – Tailored Interfaces led by Argonne National Laboratory, with Northwestern University and the University of Illinois, Urbana- Champaign as partners. · Specifically, use x-ray spectroscopic techniques, including in situ experiments, at Argonne’s Advanced Photon Source and high-resolution electron microscopy to probe and characterize the surface structures of high capacity xLi 2 MnO 3 •(1-x)LiMO 2 (M=Mn, Ni, Co) materials. Technical Barriers · Low energy density · Poor low temperature operation · Abuse tolerance limitations Technical Targets (USABC - End of life) · 142 Wh/kg, 317 W/kg (PHEV 40 mile requirement) · Cycle life: 5000 cycles · Calendar life: 15 years Accomplishments · A detailed electrochemical/structural study of lithiumnickel-phosphate-coated 0.5Li 2 MnO 3 0.5LiCoO 2 was accomplished. · One patent application, one paper accepted for publication Introduction Bulk and interfacial electrochemical processes are of fundamental scientific interest as well as of technological importance. The performance of energy storage and power supply systems is largely dependent on these processes, which can occur at an electrode-electrolyte interface or in the bulk of the electrode. In this project, the structural features, ionic transport phenomena and charge-transfer reactions at the electrode/electrolyte interface of lithium battery electrode materials, notably high potential metal oxide cathodes are studied. The electrode materials under investigation are selected specifically from those being investigated in the BATT program and on their potential for making significant advances in electrochemical performance; the studies are complementary to the research being conducted by the Energy Frontier Research Center, Electrical Energy Storage – Tailored Interfaces led by Argonne National Laboratory, with Northwestern University and the University of Illinois, Urbana- Champaign as partners. Of particular importance to this project is Argonne’s recent research in the BATT program on electrodes with integrated ‘composite’ structures, which has highlighted the possibility of designing new, high-potential and high capacity electrodes with Li 2 MnO 3 as a stabilizing component. It has been demonstrated, in particular, that it is possible to integrate Li 2 MnO 3 with layered LiMO 2 - or spinel LiM 2 O 4 components (e.g., M=Mn, Ni, Co) at the atomic level, and that these composite materials can provide an exceptionally high capacity (240-250 mAh/g), which is significantly higher than the capacity offered by conventional layered LiCoO 2 , spinel LiMn 2 O 4 and olivine LiFePO 4 electrodes. These lithium- and manganese-rich composite materials have extremely complex structures which are surprisingly stable when delithiated at high potentials (~5 V). Despite the enhanced stability of these electrode materials, it is still necessary to passivate the electrode surface to prevent electrode/electrolyte reactions from occurring, and to improve Li-ion transport at the surface, thereby enhancing the power capability of the cell. In this respect, several coating techniques and passivating agents, such as metal oxides (Al 2 O 3 , ZrO 2 ), fluorides (AlF 3 ) and phosphates (AlPO 4 ) have been shown to FY 2011 Annual Progress Report 661 Energy Storage R&D
V.F.1 Energy Frontier Research Center at ANL (ANL) Thackeray – ANL improve surface stability and rate capability of the electrode, but little is known about surface structures, or the mechanisms by which lithium-ion transport occurs at the electrode surface. The knowledge gained from these studies will be used to improve the composition and structure of electrode surfaces and to advance the overall performance of the electrodes to meet DOE’s 40-mile PHEV battery requirements. Approach Analytical techniques for probing the structureelectrochemical property relationships of lithium battery electrode materials, notably at electrode surfaces, include neutron scattering, x-ray absorption, scattering and photoelectron spectroscopy, nuclear magnetic resonance, Raman spectroscopy, Fourier transform infrared spectroscopy, and electron microscopy. In this project, analytical efforts are focused predominantly on x-ray spectroscopic techniques, including in situ experiments, and high-resolution electron microscopy. Major facilities are available at Argonne to conduct these experiments, notably at the Advanced Photon Source (APS) and the Electron Microscopy Center (EMC). Surface-protected ‘coated’ cathode materials to be studied include those with integrated ‘composite’ structures in which the coating contains specific 3d/4d transition metals which are not present in the core structure. Coatings will be applied by various techniques, for example, from solution by standard sol-gel methods or by atomic layer deposition (ALD). In situ synchrotron hard x-ray spectroscopic techniques including x-ray absorption spectroscopy (XAS), resonant and non-resonant x-ray emission spectroscopy (XES) and x-ray Raman scattering (XRS) will be used to monitor the interfacial reactions at the electrode-electrolyte interface. The important traits of these spectroscopic techniques, specifically the element specific nature and the sensitivity to dilute constituents, will allow the monitoring of changes in the electronic and atomic structures of the coatings during charge-discharge cycling or during repeated cycling. A comparison of the electrochemical properties of uncoated and coated electrodes will be made. It is envisioned that these studies will provide key information at the molecular level on the structure of the coatings, the mechanism of lithium-transport at the electrode-electrolyte interface and further provide insights into degradation mechanisms during repeated cycling. Another aspect that will be investigated is the effect of the coating on the bulk structure of the composite material itself, particularly on deintercalation at high voltages, for example 4.6 V, during the initial charge. Recent XAS studies of uncoated composite materials (such as those developed under the BATT program) have shown convincing evidence of oxygen loss during first charge at these high voltages. In coated samples, the exact oxygen loss mechanism and the possible condensation of the bulk structure might be significantly different and a detailed understanding of the local structure of the bulk should provide key insights on the structure-property relationship of the coated composites. The knowledge gained from both the bulk and interface using x-ray spectroscopic methods will feed into the design of improved electrodes to meet the 40-mile PHEV goals. In addition to studies of composite cathode structures, studies of well defined electrode surfaces will be undertaken using spectroscopic and microbeam methods. Such studies utilize the property of total external reflection of x-rays at small incident angles, which minimizes the contribution from the bulk of the material and provides interface sensitivity without sacrificing the in situ capability of hard x-rays. These spectroscopic investigations will complement the x-ray based scattering approaches which are currently an integral part of Argonne’s EFRC, Center for Electrical Energy Storage- Tailored Interfaces (CEES) effort. Results Lithium-metal-oxides remain the most promising cathode materials for high-energy-density lithium-ion batteries for plug-in hybrid electric vehicles (PHEV) and all-electric vehicles (EVs). To this end, much effort has been invested to advance these materials. However, a significant challenge that remains is the mitigation of irreversible surface damage at high potentials, which occurs with adverse consequences to the power delivery of the cathodes (i.e., rate capability). To date, several surface passivation techniques have been studied with the goal of addressing this issue in a variety of cathodes by way of 1) enhancing the conductive properties of the surface, 2) modifying the electrode surface chemistry to improve performance, and 3) providing a physical barrier which impedes reactions of the surface with the electrolyte. For this project, a dilute (5 mol%) surface treatment of lithium-nickel-phosphate (Li:Ni:PO 4 ratio = 1:1:1) was deposited on a 0.5Li 2 MnO 3 •0.5LiCoO 2 (Li 1.2 Mn 0.4 Co 0.4 O 2 ) cathode material, referred to as LNP-coated LCMO. Similar treatments have previously been reported by Kang and Thackeray to enhance electrochemical performance. However, exact structural determinations could not be made regarding the outcome of the surface treatment because the host material was itself a nickel-containing oxide, 0.5Li 2 MnO 3 •0.5LiNi 0.44 Co 0.25 Mn 0.31 O 2 , alternatively, (Li 1.2 Mn 0.52 Ni 0.18 Co 0.1 O 2 ). In the present case, the host material was chosen to be free of nickel (0.5Li 2 MnO 3 •0.5LiCoO 2 ) and, therefore, structural and chemical information obtained from XAS measurements provide direct information about electrochemical enhancements due to the Li-Ni-PO 4 treatment itself relative to untreated electrodes. The results have exciting implications for tailoring the structures and/or surfaces of high-capacity composite electrodes derived from a Energy Storage R &D 662 FY 2011 Annual Progress Report
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V. FOCUSED FUNDAMENTAL RESEARCH Int
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V.A Introduction Duong - DOE, Srini
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V.B Cathode Development V.B.1 First
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V.B.1 First Principles Calculations
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V.B.1 First Principles Calculations
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V.B.2 Cell Analysis, High-energy De
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V.B.3 Olivines and Substituted Laye
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V.B.4 Stabilized Spinels and Nano O
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V.B.4 Stabilized Spinels and Nano O
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V.B.5 The Synthesis and Characteriz
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V.B.5 Synthesis & Characterization
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V.B.6 Cell Analysis-Interfacial Pro
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V.B.6 Cell Analysis-Interfacial Pro
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V.B.7 Role of Surface Chemistry on
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V.B.8 Characterization of New Catho
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V.B.8 Characterization of New Catho
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V.B.9 Layered Cathode Materials (AN
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V.B.10 Development of High Energy C
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V.B.10 Development of High Energy C
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V.B.11 Crystal Studies on High-ener
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V.B.12 Developing Materials for Lit
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V.B.13 Studies on the Local SOC and
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V.B.13 Studies on the Local SOC and
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V.B.14 New Cathode Projects (LBNL)
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V.C.1 Nanoscale Composite Hetero-st
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V.C.1 Nanoscale Composite Hetero-st
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V.C.2 Interfacial Processes - Diagn
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V.C.3 Search for New Anode Material
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V.C.4 Nano-structured Materials as
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V.C.4 Nano-structured Materials as
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V.C.5 Development of High Capacity
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V.C.5 Development of High Capacity
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V.C.6 Advanced Binder for Electrode
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V.C.6 Advanced Binder for Electrode
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V.C.7 Three-Dimensional Anode Archi
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ARGONNE2_CDJ403T me Pro ile V.C.7 T
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V.C.8 Metal-Based High-Capacity Li-
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V.C.8 Metal-Based High-Capacity Li-
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V.C.9 New Layered Nanolaminates for
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V.C.9 New Layered Nanolaminates for
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V.C.10 Atomic Layer Deposition for
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V.C.10 Atomic Layer Deposition for
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V.C.11 Synthesis and Characterizati
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V.C.11 Polymer-Coated Layered SiOx-
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V.C.12 Synthesis and Characterizati
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V.C.12 Silicon Clathrates for Anode
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V.C.12 Silicon Clathrates for Anode
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V.C.13 Wiring Up Silicon Nanopartic
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V.C.13 Wiring Up Silicon Nanopartic
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V.C.14 Hard Carbon Materials for Hi
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V.C.14 Hard Carbon Materials for Hi
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V.D.1 Polymer Electrolytes for Adva
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V.D.1 Polymer Electrolytes for Adva
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V.D.2 Interfacial Behavior of Elect
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V.D.2 Interfacial Behavior of Elect
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V.D.3 Molecular Dynamics Simulation
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V.D.3 Molecular Dynamics Simulation
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V.D.4 Bi-functional Electrolytes fo
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V.D.4 Bi-functional Electrolytes fo
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