| Norbornene-Based Polymer Electrolytes for Lithium Cells |
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| NASA’s Jet Propulsion Laboratory, Pasadena, California | |
| Jun 30 2007 | |
These solid electrolytes are single-ion conductors.
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Norbornene-based polymers have shown promise as solid electrolytes for lithium-based rechargeable electrochemical cells. These polymers are characterized as single-ion conductors. Single-ion-conducting polymers that can be used in lithium cells have long been sought. Single-ion conductors are preferred to multiple-ion conductors as solid electrolytes because concentration gradients associated with multiple-ion conduction lead to concentration polarization. By minimizing concentration polarization, one can enhance charge and discharge rates.
 This Sequence of Reactions yields a cyclopentane-based polymer structure that includes sulfonate ionomers attached to the backbones. Li+ ions are loosely bound to the sulfonate ionomers. This molecular system is especially attractive in that it is highly amenable to modification through functionalization of the backbone or copolymerization with various monomers. Polymers of this type have been blended with poly(ethylene oxide) to lend mechanical integrity to free-standing films, and the films have been fabricated into solid polymer electrolytes. These electrolytes have been demonstrated to exhibit conductivity of 2 × 10–5 S·cm (which is high, relative to the conductivities of other solid electrolytes) at ambient temperature, plus acceptably high stability. This type of norbornene-based polymeric solid electrolyte is in the early stages of development. Inasmuch as the method of synthesis of these polymers is inherently flexible and techniques for the fabrication of the polymers into solid electrolytes are amenable to optimization, there is reason to anticipate further improvements. This work was done by Iris Cheung and Marshall Smart of Caltech and Surya Prakash, Akira Miyazawa, and Jinbo Hu of the University of Southern California for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Materials category.
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Norbornene-Based Polymer Electrolytes for Lithium Cells (reference NPO-41134) is currently available for download from the TSP library. Login first to download.
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