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V.B.10 Development of High Energy Cathode (PNNL) Ji-Guang Zhang and Jun Liu Pacific Northwest National Laboratory 902 Battelle Blvd., Mail Stop K3-59 Richland, WA 99352 Phone: (509) 372-6515; (509) 375-4443 E-mail: jiguang.zhang@pnl.gov; jun.liu@pnl.gov; Start Date: October 1, 2010 Projected End Date: September 30, 2011 Objectives · Develop high-energy cathode materials with improved safety. · Develop low-cost synthesis routes for high-capacity and environmentally-benign cathode materials. Technical Barriers This project addresses the following technical barriers: · High cost of cathode materials. · Limited energy density and cyclability. · Safety. Technical Targets · Investigate the electrochemical performances of LiMnPO 4 synthesized from non-stoichiometric Li/Mn ratio; evaluate thermal stability of electrochemically de-lithiated LiMnPO 4 · Develop a cost-effective method to prepare highvoltage spinel LiNi 0.5 Mn 1.5 O 4 ; identify appropriate electrolyte additives to improve Coulombic efficiency · Explore the renewable organic cathode materials with 2e - transfer per redox center. Accomplishments · Systematically studied the thermal stability of a delithiated LiMnPO 4 cathode · Investigated the influence of lithium content in the starting material on the final structural and electrochemical performances of Li x MnPO 4 (0.5≤x≤1.2) · Developed a facile synthesis approach for highvoltage spinel. A Cr-substituted spinel, LiNi 0.45 Cr 0.05 Mn 1.5 O 4 , shows excellent cycle stability; the Coulombic efficiency and the first cycle loss were greatly improved after the addition of appropriate electrolyte additive. · Synthesized poly(1,8-anthraquinonyl sulfide (P18AQS), a new organic cathode material, as a highcapacity cathode material. Introduction · Li-ion batteries with high energy densities are required to reach DOE’s goal regarding early commercialization of electrical vehicles, including hybrid electric vehicles and plug-in hybrid electric vehicles. To increase the energy of a cathode, the voltage and/or capacity of the material must be increased. During FY 2011, we further investigated the thermal stability of LiMnPO 4 , and we were able to improve its synthesis approaches. By adding appropriate doping and electrolyte additives, we successfully developed a chromium doped highvoltage spinel, LiNi 0.45 Cr 0.5 Mn 1.5 O 4 . This material exhibited stable cycling and greatly improved efficiency. We also synthesized a novel renewable organic cathode, P18AQS, and we studied its electrochemical performance to advance our understanding on the renewable cathode materials. Approach Investigate the final structural compositions and electrochemical performances of LiMnPO 4 synthesized with different lithium contents · Characterize the phase transformation and oxygen evolution temperature of electrochemically delithiated MnPO 4 to evaluate thermal stability · Synthesize high-performance LiNi 0.5 Mn 1.5 O 4 and its Cr-substituted phase, which will provide the basis for identifying electrolyte additives to improve the Coulombic efficiency for high-voltage cathodes. · Synthesize and evaluate novel high-capacity organic cathodes based on the quinonyl group. Results Thermal stability of Electrochemically Delithiated MnPO 4 . For thermal stability studies, the charged LiMnPO 4 paper electrodes and MnPO 4 H 2 O powder (as a control) were subjected to in situ, hot-stage XRD at every FY 2011 Annual Progress Report 513 Energy Storage R&D
V.B.10 Development of High Energy Cathode (PNNL) Zhang, Liu – PNNL 30°C increment up to 534°C in a UHP-Ar atmosphere as lithiated MnPO 4 can be summarized by the following shown in Fig. 1. We observed MnPO 4 reduction to reaction: Mn 2 P 2 O 7 with oxygen evolution at 490°C, which coincides o o 150~180 C 490 C 1 1 MnPO 4 MnPO 4 Mn 2PO 2 7 O 2 with the phase changes in MnPO 4 H 2 O. Between 180 and Pnma Jahn Teller Distortion 2 C2/ m 2 490°C, the charged MnPO 4 undergoes amorphization (highlighted yellow area in Figure V - 51). TGA-MS results Our results demonstrate the intrinsic thermal stability showed no oxygen released before reaching 490°C. of electrochemically lithiated or de-lithiated LiMnPO However, initial CO 2 release between 200~400°C was 4 . However, the discharge rate of LiMnPO observed for the charged MnPO 4 electrode consistent with 4 needs to be improved for their practical application. Because heat the weight changes observed in the TGA plot indicating evolution related to the LiMnPO that the continuous weight loss up to 450°C resulted from 4 cathode is an extrinsic material property and not an intrinsic property, smart decomposition of the SEI layer formed on the LiMnPO 4 material design, such as carbon coating, can significantly electrode surface. CO 2 evolution is commonly observed reduce surface-electrolyte reactions better than during oxidation at the SEI layer and catalytic Li(NiCoX)O decomposition of carbonate-based organic electrolytes. 2 (X: Mn or Al) compounds in terms of both onset temperatures and specific heat evolution. The thermal stability and phase transformation of the de- Figure V - 51: In situ, hot-stage XRD characterization of (a) the charged MnPO4 electrode and (b) the MnPO4H2O powder under an UHP-Ar atmosphere (heating rate: 5°C /min). LiMnPO 4 Synthesized from a Non-Stoichiometric Li:Mn Ratio. The influences of lithium contents in the starting materials on the final performance of Li x MnPO 4 (x hereafter represents the starting Li content in the synthesis step, which does not necessarily mean that Li x MnPO 4 is a single phase solid solution in this work) were investigated systematically. From the results of ICP mass spectroscopy, the Li:Mn ratio matched very well with the designed compositions, which confirms that the precipitation method is a feasible approach for tuning the lithium content in the final product. Rietveld refinement of the XRD data shown in Figure V - 52 revealed that Mn 2 P 2 O 7 is the main impurity when x 1.0. Magnetic and XAS studies further confirmed that the main phase in Li x MnPO 4 samples was LiMnPO 4 , and the variation in Li content leads to the formation of additional Li-contained (Li 3 PO 4 ) or Mn-contained (Mn 2 P 2 O 7 ) phases to accommodate the stoichiometry. The as-prepared Li 0.8 MnPO 4 , which is a Li deficient phosphate, is quite different from chemically delithiated Li x MnPO 4 because other byproducts, such as a Mndeficient phase, may occur during the interactions between LiMnPO 4 and the oxidant (usually NO 2 BF 4 dissolved in acetonitrile), thus influencing or hiding the physical and electrochemical properties of the material itself. For Li 0.5 MnPO 4 and Li 0.8 MnPO 4 , gradual increases in the reversible capacity with cycling were observed, Figure V - 53, which may be related to interactions between Mn 2 P 2 O 7 and LiMnPO 4 . Among all the samples, Li 1.1 MnPO 4 exhibits the most stable cycling probably because of the Li 3 PO 4 coating on the surface of LiMnPO 4 nano-particles that functions as a solid electrolyte to facilitate ion transport. Therefore the electrochemical performance of Energy Storage R &D 514 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 and 24: V.B.5 The Synthesis and Characteriz
Page 25 and 26: V.B.5 Synthesis & Characterization
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 45 and 46: V.B.9 Layered Cathode Materials (AN
Page 47: V.B.9 Layered Cathode Materials (AN
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
Page 75 and 76: V.C.2 Interfacial Processes - Diagn
Page 81 and 82: V.C.3 Search for New Anode Material
Page 83 and 84: V.C.4 Nano-structured Materials as
Page 85 and 86: V.C.4 Nano-structured Materials as
Page 87 and 88: V.C.5 Development of High Capacity
Page 89 and 90: V.C.5 Development of High Capacity
Page 91 and 92: V.C.6 Advanced Binder for Electrode
Page 93 and 94: V.C.6 Advanced Binder for Electrode
Page 95 and 96: V.C.7 Three-Dimensional Anode Archi
Page 97 and 98: 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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