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| Texas NanoEnergy Collaborative |
Principal Investigator
Arumugam Manthiram, PhD [ Bio]
Professor of Mechanical Engineering
University of Texas at Austin
Project Period: 06/01/2007 - 09/30/2008
NASA is engaged in a number of challenging missions for robotic and human exploration of space, and power supply and energy storage are critical components of these missions. The energy storage needs for the robotic and human surface exploration missions differ significantly from the conventional orbital missions. The primary performance requirements for surface exploration missions are mass and volume efficiencies, ability to operate at low temperatures, and long operational life. Lithium ion batteries are attractive in this regard as energy storage devices for NASA missions since they offer much higher mass and volume energy densities compared to other rechargeable battery systems. However, the currently employed layered lithium cobalt oxide cathode has limited energy density, suffers from safety concerns, and is expensive. The proposed project focuses on the development of less expensive layered oxide cathodes that offer two times higher energy density than the currently used cobalt oxide cathode with significantly improved safety features.
Utilizing extensive prior basic science work in the PI's laboratory, this proposal focuses on the development of layered oxide cathodes that are richer in nickel and manganese such as Li[Ni1-x-y-zMnxLiyCoz]O2. These complex layered oxide cathodes exhibit higher capacities (~ 250 Ah/kg) compared to the currently used LiCoO2 cathode (140 Ah/kg) with good cyclability due to the better chemical stability of the Ni3+/4+ and Mn3+/4+ redox couples.
However, these high capacity cathodes:
- Encounter an irreversible loss of oxygen from the lattice during the first charge,
- Have lower power capability, and
- Exhibit huge irreversible capacity losses of 40 - 100 Ah/kg in the first cycle.
This proposal aims to address these issues by the following approaches:
- optimization of the layered Li[Ni1-x-y-zMnxLiyCoz]O2 compositions via cationic and anionic substitutions to improve rate (power) capability and suppress oxygen loss,
- coating of the layered oxides with nanostructured metal oxides like Al2O3 to minimize the undesired reaction of the cathode surface with the electrolyte and thereby to reduce the irreversible capacity loss and increase the discharge capacity values to at least 280 Ah/kg, and
- incorporation of moderate amounts of high power spinel oxide cathodes into these high capacity layered oxide cathodes to improve the rate capability and achieve a combination of high capacity and power in the layered-spinel nanocomposite cathodes.
The oxides will be synthesized by both solid state and solution-based approaches and the nanostructured coating will be pursued with a variety of solution-based chemical methods. The materials will be characterized by X-ray diffraction, chemical analysis, scanning electron microscopy, transmission electron microscopy, thermal analysis, and electrochemical measurements. Electrochemical data will be collected with coin cells to assess the performance parameters like capacity, cyclability, power capability, and low and high-temperature performances.
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| Page Updated/Reviewed: 02/27/2008 8:39 AM |
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