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Battaglia – LBNL V.E.1 Electrode Fabrication and Failure Analysis (LBNL) These results show that, for fresh powders, the dissolution is completed after the first week and is equivalent to just 0.1 % of the transition metals. It is possible that these results are measuring the amount of dissoluable impurity species in the cathode. These experiments will be followed-up by similar experiments with the electrode charged to differend states-of-charge. Conclusions and Future Directions Previous work, either performed in our lab or published in the literature, has indicated that side reactions play a critical role in cell capacity fade, especially for those materials where cycleability beyond 1000 cycles is possible. We have found that not all of the side reactions are detrimental and thus may be the result of a shuttle that is formed during the first charge. We are attempting to measure the rates of these reactions and to isolate the shuttle. LBNL has initiated a focus group on high-voltage electrodes/electrolyte. The baseline materials are LiNi 1/2 Mn 3/2 O 4 from NEI and 1 M LiPF 6 in EC:DEC 1:2. Cycling has been performed with lithium and graphite as the counterelectrode. The upper cutoff limit when cycling against Li at C/10 is 4.88 V and against graphite is 5.3 V. Cells cycled against graphite have side reactions that are 4 times the rate of capacity fade and suggest a shuttle is active in the cell. Dissolution experiments reveal that the fresh powder losses about 0.1 % of the transition metals after 1 week at 55°C. Future efforts will be dedicated to understanding the source of the shuttle, the composition of expected gasses, and the source of the gasses. We are also looking to test advanced electrolytes and cathodes from other suppliers to determine the uniqueness of each. We also expect to take up a study of electrode fabrication procedures in identifying those sources that make for the largest contributions to cell-to-cell variability. FY 2011 Publications/Presentations 1. 2011 DOE Annual Peer Review Meeting Presentation. FY 2011 Annual Progress Report 631 Energy Storage R&D
V.E.2 Modeling-Thermo-electrochemistry, Capacity Degradation and Mechanics with SEI Layer (UM) Ann Marie Sastry University of Michigan 2350 Hayward St. Ann Arbor, MI 48109 Phone: (734) 998-0006; Fax: (734) 998-0028 E-mail: amsastry@umich.edu Start Date: October 1, 2008 Projected End Date: September 30, 2011 Objectives · Create a multiscale finite element (FE) model that considers self-assembled structure in order to evaluate the effective electrochemical properties of the aggregated particles · Perform numerical studies of capacity fade due to the SEI layer and stress analysis/mechanical stability of the SEI layer in anode particles · Characterize the SEI layer and investigate the effect of different environmental conditions on SEI layer formation through experimental techniques Technical Barriers Inadequate power and life in PHEV systems Technical Targets · Available energy: 56 Wh/kg (10 mile) and 96 Wh/kg (40 mile) · 10 s discharge power: 750 W/kg (10 mile) and 316 W/kg (40 mile) · Cycle life: 5,000 cycles · Calendar life: 15 years Accomplishments · Development of a multiscale FE model including particle aggregation of active and additive materials in order to determine the effective electrochemical properties of the electrode material · Demonstration of capacity fade due to the SEI layer via a multiphysics model that considers film resistance and the double-layer charging current · Demonstration of the stress evolution in both the active particle and SEI layer by considering a misfit between the two phases · Measurement of EIS and XPS for the resistance variation due to the SEI layer and the concentration change of elements in the surface of the SEI layer Introduction In order for battery performance to improve, the failure mechanisms of Li-ion batteries, which involve many mechanisms such as active material dissolution, SEI layer evolution, mechanical instabilities, and thermal failure, have to be understood and minimized. As an extension of multiscale thermo-electrochemistry modeling in FY2010, this model was refined based on the findings from simulated performances and experimental observations. The improved model enabled us to investigate such key battery performance-determining parameters as multi-phase particle structure and SEI layer structure. SEI formation in composite electrode microstructures and its effect on battery kinetics were investigated via both experimental and numerical tools. Improved prediction of lifetime in Li-ion battery cells will be informed by exploring capacity degradation in composite multi-phase electrodes in the context of both multiple scales and multiphysics that considers electrochemical kinetics Approach Aggregation between additive particles and active particles in the electrode material of batteries strongly affects their interfacial impedance and power performance. A three dimensional model that simulates the aggregation process of carbon black and LiMn 2 O 4 active material particles within a liquid medium (PVDF polymer dissolved in NMP solvent) was developed. A Brownian dynamics was employed in the simulation and the resulting aggregates are exported to multiphysics finite element models. This model was then used to evaluate effective material properties by applying a volume averaging theory. A mathematical model that includes film resistance and the double-layer charging current was developed, and this model was coupled with a frequency responses analysis in order to characterize capacity fade due to SEI layer formation. Also calculated were the stress evolutions Energy Storage R &D 632 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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Page 117 and 118: V.C.12 Silicon Clathrates for Anode
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Page 121 and 122: V.C.13 Wiring Up Silicon Nanopartic
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Page 125 and 126: V.C.14 Hard Carbon Materials for Hi
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Page 129 and 130: V.D.1 Polymer Electrolytes for Adva
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Page 133 and 134: V.D.2 Interfacial Behavior of Elect
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Page 137 and 138: V.D.3 Molecular Dynamics Simulation
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Page 141 and 142: V.D.4 Bi-functional Electrolytes fo
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Page 163 and 164: V.E Cell Analysis, Modeling, and Fa
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Page 171 and 172: V.E.3 Intercalation Kinetics and Io
Page 177 and 178: V.E.4 Mathematical Modeling of Next
Page 179 and 180: V.E.5 Analysis and Simulation of El
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Page 183 and 184: V.E.6 Investigation of Critical Par
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Page 193 and 194: V.E.9 In Situ Electron Spectroscopy
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Page 201 and 202: V.F.2 Novel In Situ Diagnostics Too
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Page 205 and 206: V.G Integrated Lab-Industry Researc
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