BATTERIES FOR ADVANCED TRANSPORTATION TECHNOLOGIES

The Batteries for Advanced Transportation Technologies (BATT) Program is supported by the U.S. Department of Energy Office of Advanced Automotive Technologies (DOE/OAAT) to help develop high-performance rechargeable batteries for use in electric vehicles (EVs) and hybrid-electric vehicles (HEVs). The work is carried out by the Lawrence Berkeley National Laboratory (LBNL) and several other organizations, and is organized into six separate research tasks.

Background and Program Focus

The development of an advanced battery for automotive applications is a difficult undertaking. There is a strong need to identify and understand performance and lifetime limitations to help guide battery scale-up and development activities. High cell potentials and demanding cycling requirements lead to chemical and mechanical instabilities, which are important issues that must be addressed.

The BATT Program addresses fundamental issues of chemistries and materials that face all lithium battery candidates for DOE EV and HEV applications. The Program emphasizes synthesis of components into battery cells with determination of failure modes, coupled with strong efforts in materials synthesis and evaluation, advanced diagnostics, and improved electrochemical models. The selected battery chemistries are monitored continuously with periodic substitution of more-promising components. This is done with advice from within the BATT Program, from outside experts, and from assessments of world-wide battery R&D activities such as that prepared for the California Air Resources Board [1].

The BATT Program also educates battery and electrochemical scientists who move on to work for battery developers.

Task Descriptions

The six primary BATT Program task areas are: (1) Cell Development, (2) Anodes, (3) Electrolytes, (4) Cathodes, (5) Diagnostics, and (6) Modeling. Task 1 comprises cell fabrication, testing and characterization , Tasks 2-4 are aimed at identifying new materials, and Tasks 5-6 support all BATT Program work. Brief summary descriptions of each task follow.

The Cell Development task has identified three "baseline" rechargeable lithium cell chemistries. The polymer-electrolyte cell chemistry includes a Li negative electrode [2], Li(CF3SO2)2N + cross-linked PEO-based electrolyte [3a,b] , and V6O13 or another compatible positive electrode [4]. The gel-electrolyte cell chemistry includes a graphite negative electrode [5] or a high-capacity Sn-based electrode with acceptable stability, LiBF4 + cross-linked gel electrolyte [6], and a LiFePO4 [7] or Li1.02Al0.25Mn1.75O3.97S0.03 [8] positive electrode. The baseline (DOE/ATD Program Gen 2) Li-ion chemistry is graphite + PVDF binder negative electrode, LiPF6-EC-EMC electrolyte, and LiAl0.05Ni0.80Co0.15O2 + graphite + acetylene black + PVDF positive electrode, and is described in reference [9]. A web page is under development for reporting cell test data.

The Anodes task seeks to characterize and improve graphitic and other carbon materials, as well as conduct exploratory research on non-carbonaceous anode materials. Every commercial Li-ion battery uses some form of carbon as its anode material, and these batteries suffer from safety, cycle life, and storage-life problems. It is for these reasons that either improved carbons or non-carbonaceous anodes must be developed as possible alternatives. Low-cost metal alloys with acceptable capacity, rate, cyclability, and calendar life are under investigation.

Polymer Electrolyte research aims to understand performance characteristics by studies of the transport properties of the electrolyte as a function of polymer and salt structure, polymer structural changes as a function of temperature, and interactions at the electrode/electrolyte interface related to transport and chemical/mechanical stability. A multi-pronged approach involving chemical synthesis, advanced diagnostic tools, and coordinated modeling studies is being used. The development of non-flammable electrolytes (NFEs) and novel electrolyte additives is recognized as a critical need for Li-ion battery technology. We seek to identify advanced NFEs and electrolyte additives to determine their effectiveness for liquid-based Li-ion batteries.

The identification and development of novel Cathodes is critical because of the fundamental limitations of cobalt-based and vanadium-based materials used in present-day rechargeable Li batteries. For example, Co is priced at $140/kg, which is inconsistent with EV and HEV cost targets. The focus of this effort is to develop a high-rate and stable MnO2 cathode. Although Mn is a low-cost constituent, MnO2 cathodes tend to lose capacity at an unacceptable rate. Research is directed at understanding the reasons for the capacity fade and developing methods to stabilize this material, as well as the evaluation of novel forms of MnO2 cathodes.

Advanced Diagnostics are essential to investigate life-limiting and performance-limiting processes in batteries. We use post-test analyses and enhanced spectroscopic and microscopic techniques to investigate morphology, structure, and compositional changes of electrode materials. Examples include providing better understanding the solid electrolyte interphase (SEI) layers formed on carbon through ellipsometric techniques, and a detailed investigation of the lithium/polymer interface via advanced microscopies and spectroscopies.

Sophisticated Modeling is required to support BATT Program Tasks 1-5. This effort brings physical understanding to complex interactions through the development of comprehensive phenomenological models. Models are being advanced to elucidate the failure mechanisms of lithium battery components and to understand the mechanisms for thermal runaway.

References

1. M. Anderman, F. Kalhammer and D. MacArthur, "Advanced Batteries for Electric Vehicles: An Assessment of Performance, Cost and Availability" (June 2000).

2. M. Gauthier, A. Belanger and A. Vallee, "Rechargeable Lithium Anode for Polymer Electrolyte Battery," US Patent #6,007,935 and references therein.

3. a) A. Vallee, M. Duval, F. Brochu, M. Kono, E. Hayashi and T. Sada, "LPB Electrolyte Compositions Based on Mixtures of Copolymers and Interpenetrated Networks," US Patent # 5,755,985; b) O. Buriez, Y. B. Han, J. Hou, J B. Kerr, J. Qiao, S. E. Sloop, M. Tian and S. Wang, "Performance Limitations of Polymer Electrolytes Based on Ethylene Oxide Polymers." J. Power Sources, 89, 149 (2000).

4. a) M.M. Thackeray, A.J. Kahaian, D.R. Vissers, D.W. Dees and R. Benedek, "Modified Lithium Vanadium Oxide Electrode Materials, Products and Methods, " US Patent # 6,004,697; b) K. West, B. Zachau-Christiansen and T. Jacobsen," Electrochemical Properties of Non-Stoichiometric V6O13," Electrochim. Acta, 28, 1829 (1983); c) W.J. Macklin, R.J. Neat and S.S. Sandhu, "Structural Changes in Vanadium Oxide-Based Cathodes During Cycling in a Lithium Polymer Electrolyte Cell," Electrochim. Acta, 37, 1715 (1992); d) K. E. Thomas, S. Sloop, J. Kerr and J. Newman, "Comparison of Lithium-Polymer Cell Performance with Unity and Nonunity Transference Numbers," J. Power Sources, 89, 132 (2000).

5. K. Kezuka, T. Htazawa and K. Nakajima, "The Status of Sony Li-ion Polymer Battery," Abstract No. 4, 10th International Meeting on Lithium Batteries, The Electrochemical Society, Inc. See also abstracts 363 and 374 at the same meeting.

6. M M. Kono, E. Hayashi, M. Nishiura and M. Watanabe, "Characterization of Polymer Gel Electrolytes Based on a Poly(alkylene oxide) Macromonomer," J. Electrochem. Soc. , 147, 2517 (2000). See also M. Kono, E. Hayashi and M. Watanabe, J. Electrochem. Soc., 146, 1626 (1999).

7. A.S. Andersson, J.O. Thomas, B. Kalska and L. Häggströmb, "Thermal Stability of LiFePO4-Based Cathodes," Electrochemical and Solid-State Letters, 3, 66-68 (2000)

8. S.H. Park, K.S. Park, Y.K. Sun and K.S. Nahm, "Synthesis and Characterization of a New Spinel Li1.02Al0.25Mn1.75O3.97S0.03 Operating at Potentials Between 4.3 and 2.4 V", J. Electrochem. Soc., 147, 2116 (2000). See also Y.-K. Sun, Y.-S. Jeon and H. J. Lee," Overcoming Jahn-Teller Distortion for Spinel Mn Phase," Electrochemical and Solid-State Letters, 3, 7 (2000)

9.  Annual Progress Reports for the Advanced Technology Development Program, Argonne National Laboratory.

Recent Annual Reports

1999

Recent Quarterly Reports

July1999

October 1999

January 2000

April 2000

July 2000

October 2000

January 2001

April  2001


A bi-weekly BATT Program seminar is held at LBNL.


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