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Whittingham – Binghamton U. V.B.5 Synthesis and Characterization of Substituted Olivines and Mn Oxides (Binghamton U.) materials. To meet the DOE cost targets, we are looking at reducing high-cost components and for power and energy targets at modifying the chemical composition and morphology of the cathode compounds. Approach Our cathode approach is to place emphasis on low cost materials, predominantly oxides and phosphates, both pure and modified with other transition metals, using a range of practical synthesis approaches. These materials will be synthesized, and characterized both structurally, including defects and morphology, and for thermal and chemical stability. All will be evaluated electrochemically in a range of cell configurations. For the modified layered dioxides, we are determining the role of each of the transition metals, with the goal of minimizing expensive components such as cobalt. To that end, we are studying the layered compositions, LiNi y Mn y Co 1-2y O 2 , with a close to stoichiometric Li to transition metal ratio and comparing them to the Li-rich Mn-rich compounds. We are also searching for new classes of materials that might react with more than one lithium ion per redox center. Phosphates are one area for our search and vanadium containing materials another area. Results Layered Transition Metal Oxides. We formed a range of transition metal oxides of formula LiNi y Mn y Co 1 2yO 2 to determine the optimum composition for both energy density and power density. The voltage/capacity curves were determined and found to depend little on the chemical composition except at low values of the lithium content, when the redox of Co becomes involved and pushed the potential higher. The lower cobalt material with y = 0.4 showed as good electrochemical behavior as the commonly used LiNi 1/3 Mn 1/3 Co 1/3 O 2 material, except at the highest discharge rates. In collaboration with C. Ban and A. Dillon at NREL, the rate behavior was determined and shown to be excellent as indicated in Figure V - 23. Full details are given in publication #3 listed below. Figure V - 23: High-rate cycling of LiNi0.4Mn0.4Co0.22O2, using carbon nanotube mesh grid. The results, shown in Figure V - 23, clearly show that the layered materials can deliver high rates when the electrode is configured optimally. Our earlier work showed that a manganese content exceeding 0.5 in the formula Li[Ni 1-y-z Mn y Co z ]O 2 is detrimental to the rate capability of these layered oxides with a Li/M ratio of unity. This year we expanded the study to the lithium-rich oxides described by the mixture yLi 2 MnO 3 •(1-y)LiNi 0.4 Mn 0.4 Co 0.2 O 2 , where y=0.5 giving an overall composition of Li 1.2 Ni 0.16 Mn 0.56 Co 0.08 O 2 . The results were somewhat surprising, with the rate capacities being worse than the Li/M stoichiometric material at higher rates, but this material also showed very poor thermal stability, no better than NCA. Although the thermal stability could be improved by substitution of some of the cobalt by aluminum, it is still much worse than LiNi 1/3 Mn 1/3 Co 1/3 O 2 and LiNi 0.4 Mn 0.4 Co 0.4 O 2 as shown in Figure V - 24. Aluminum contents above 5% do not seem to further stabilize the compound. As earlier work from Argonne National Lab has shown good stability for the Lirich Li 1+y [Ni 1/3 Mn 1/3 Co 1/3 ] 1-y O 2 the instability is probably associated with the high manganese content. Thus, our conclusions of this layered oxide study are that the manganese content should probably be kept at less than 50% of the transition metal and also no higher than the nickel content in order to achieve high rates in a safe cathode. FY 2011 Annual Progress Report 489 Energy Storage R&D
V.B.5 Synthesis & Characterization of Substituted Olivines and Mn Oxides (Binghamton U.) Whittingham – Binghamton U. Figure V - 24: Differential scanning calorimetry at 10/min of delithiated Li1.2Ni0.16Mn0.56Co0.08-yAlyO2 (y = 0, 0.048, 0.08) compared with the more stable NMC electrodes, LiNi0.33Mn0.33Co0.33O2 and LiNi0.4Mn0.4Co0.2O2. Higher Capacity Electrodes – Pyrophosphates. The pyrophosphate, Li 2 FeP 2 O 7 , can have a capacity well in excess of 200 Ah/kg. Working with Primet in Ithaca we have nanosized the compound, and tested a number of electrolytes. The results are shown in Figure V - 25. Although there is still a large amount of side-reactions above 5 volts, we are now achieving capacities that exceed one Li per iron (110 mAh/g). The maximum discharge capacity obtained is around 150 mAh/g, and we hope with still improved electrolyte to exceed 200 mAh/g and achieve 700 Wh/kg and at a higher volumetric energy density than LiFePO 4 . The student has studied a number of ionic liquids at Monash University, but none have shown the required stability to date. We continue our collaboration with G. Ceder at MIT to determine the operating potentials of these systems. Studies are continuing on vanadium based oxides and phosphates, as vanadium offers the opportunity for a two electron redox process between V 5+ and V 3+ . We have formed novel vanadium oxides and mixed phases of lithium vanadium phosphate. The Ceder group has also identified the VOPO 4 class of material as the most promising of the phosphates. Figure V - 25: Comparison of the cycling performance for the C-coated Li2FeP2O7 material nanosized by Primet using the EC/DMC electrolyte and the sulfone-based electrolyte from PNNL. The loading of the active material is around 4 mg for the EC/DMC and 5.3 mg for the sulfone with the electrode area of 1.2 cm 2 . The cycling rate is C/20. Conclusions and Future Directions 200 Ah/kg can only be obtained from the layered oxides at the C rate if charging is in excess of 4.4 volts, but more stable electrolytes will be needed. Collaborative work with NREL showed that LiNi 0.4 Mn 0.4 Co 0.2 O 2 has an inherent high discharge rate. Increasing both the lithium and the manganese content did not lead to higher energy densities at the 2C rate. Moreover, these manganese-rich compounds show remarkably poor thermal stabilities, no better than NCA, which can be improved by the substitution of some of the cobalt by aluminum but are still much less stable than NMC. The pyrophosphate’s electrochemical performance can be improved by nanoscissoring, but the stability limit of the electrolyte is being exceeded. Future work will complete the pyrophosphate project and get initial data on a range of vanadyl phosphates. The project is due to finish in December 2011. FY 2011 Publications/Presentations 1. Presentation to the 2011 DOE Annual Peer Review Meeting, Washington, DC. Energy Storage R &D 490 FY 2011 Annual Progress Report
Page 1 and 2: V. FOCUSED FUNDAMENTAL RESEARCH Int
Page 3 and 4: V.A Introduction Duong - DOE, Srini
Page 5 and 6: V.B Cathode Development V.B.1 First
Page 7 and 8: V.B.1 First Principles Calculations
Page 9 and 10: V.B.1 First Principles Calculations
Page 11 and 12: V.B.2 Cell Analysis, High-energy De
Page 13 and 14: V.B.3 Olivines and Substituted Laye
Page 19 and 20: V.B.4 Stabilized Spinels and Nano O
Page 21 and 22: V.B.4 Stabilized Spinels and Nano O
Page 23: V.B.5 The Synthesis and Characteriz
Page 27 and 28: V.B.6 Cell Analysis-Interfacial Pro
Page 29 and 30: V.B.6 Cell Analysis-Interfacial Pro
Page 31 and 32: V.B.7 Role of Surface Chemistry on
Page 39 and 40: V.B.8 Characterization of New Catho
Page 41 and 42: V.B.8 Characterization of New Catho
Page 43 and 44: V.B.9 Layered Cathode Materials (AN
Page 49 and 50: V.B.10 Development of High Energy C
Page 51 and 52: V.B.10 Development of High Energy C
Page 53 and 54: V.B.11 Crystal Studies on High-ener
Page 59 and 60: V.B.12 Developing Materials for Lit
Page 65 and 66: V.B.13 Studies on the Local SOC and
Page 67 and 68: V.B.13 Studies on the Local SOC and
Page 69 and 70: V.B.14 New Cathode Projects (LBNL)
Page 71 and 72: V.C.1 Nanoscale Composite Hetero-st
Page 73 and 74: 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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V.D.5 Advanced Electrolyte and Elec
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V.D.6 Inexpensive, Nonfluorinated (
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V.D.6 Nonfluorinated (or Partially
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V.D.7 Development of Electrolytes f
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V.D.8 Sulfones with Additives as El
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V.D.8 Sulfones with Additives as El
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V.D.9 Long-lived Polymer Electrolyt
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V.E Cell Analysis, Modeling, and Fa
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V.E.1 Electrode Fabrication and Fai
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V.E.2 Modeling-Thermo-electrochemis
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V.E.2 Thermo-electrochemistry, Capa
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V.E.3 Intercalation Kinetics and Io
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V.E.4 Mathematical Modeling of Next
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V.E.5 Analysis and Simulation of El
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V.E.5 Analysis and Simulation of El
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V.E.6 Investigation of Critical Par
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V.E.6 Investigation of Critical Par
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V.E.7 Predicting/Understanding New
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V.E.8 New Electrode Designs for Ult
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V.E.8 New Electrode Designs for Ult
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V.E.9 In Situ Electron Spectroscopy
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V.E.9 In situ Electron Spectroscopy
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V.F.1 Energy Frontier Research Cent
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V.F.1 Energy Frontier Research Cent
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V.F.2 Novel In Situ Diagnostics Too
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V.F.2 Novel In Situ Diagnostics Too
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V.G Integrated Lab-Industry Researc
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